CA2155822C

CA2155822C - Multi-functional material with photocatalytic functions and method of manufacturing same

Info

Publication number: CA2155822C
Application number: CA 2155822
Authority: CA
Inventors: Toshiya Watanabe; Eiichi Kojima; Keiichiro Norimoto; Tamon Kimura; Mitsuyoshi Machida; Makoto Hayakawa; Atsushi Kitamura; Makoto Chikuni; Yoshimitsu Saeki; Tatsuhiko Kuga; Yasushi Nakashima
Original assignee: Toto Ltd
Current assignee: Toto Ltd
Priority date: 1993-12-10
Filing date: 1994-12-09
Publication date: 2004-02-17
Anticipated expiration: 2014-12-09
Also published as: KR100358851B1; US5853866A; KR100361563B1; WO1995015816A1; US6268050B1; CA2155822A1; KR100361564B1; US6027797A; HK1085719A1; US6210779B1; US6294246B1; US6294247B1; KR100357482B1

Abstract

Multi-functional materials are classified into those which have a photocatalytic layer 2 with a photocata- lytic function directly disposed on the surface of a base 1 and those which have a photocatalytic layer 2 with a photo- catalytic function disposed on the surface of a base 1 through a binder layer 6 interposed therebetween. Photo- catalytic particles of the photocatalytic layer 2 are joined together by a surface energy or solid-state sintering. The photocatalytic layer 2 may have a structure in which fine particles fill interstices defined between photocatalytic particles or a structure in which no fine particles fill interstices defined between photocatalytic particles. A metal such as Ag, Pt, or the like may be fixed or not fixed to surfaces of the photocatalytic particles.

Description

SPECIFICATION
MULTI-FUNCTIOIJAL MATERIAL WITH PHOTOCATALYTIC FUNCTIONS
AND METHOD OF MANUFACTURING SAME
TECHNICAL FIELD:
The present invention relates to a multi-functi~aal material capable of performing various functions including a deod~~rizing function, an antibacterial function, a bactericidal function, and a stain-resistant function, and a method of manufacturing such a multi-functional material.
BACKGROUND ART:
TiOz, VZOS, ZnO, W03, etc. have heretofore been known as substances which, when irradiated by ultraviolet radiation, cause oxygen molecules to be adsorbed to or desorbed from an organic compound such as of a smelly con-stituent for promoting decomposition (oxidation) of the or-ganic compound. Since particles of Ti02 whose crystallized form is anatase, in particular, are highly effective for use as a photocatalyst, it has been proposed to form a photo-catalytic layer of TiO~ particles on the surface of walls, tiles, glass (mi.rror), circulatory filter units, or sanitary ware.
Known processes of depositing such a photocata-lytic layer of Z~i02 particles directly on the surface of a base of plastic, ceramic, or resin include the CVD process, the sputtering process, and the electron beam evaporation process.
However, the CVD process, the sputtering process, and the electron beam evaporation process require large-scale equipment, and result in a high manufacturing cost due to a poor yield.
According to other known processes of forming a photocatalytic layer, photocatalytic particles are kneaded with a binder and coated on the surface of a base by spray coating or dip coating, and thereafter heated (see Japanese laid-open patent publication No. 5-201747).
For photocatalytic particles such as TiOz parti-cles to function effectively as a photocatalyst, it is nec-essary that the photocatalytic particles be irradiated with ultraviolet radiation and held in contact with a substance to be decomposed thereby such as a smelly gas or the like.
Kneading photocatalytic particles with a binder and coating them on the surface of a base as disclosed in Japanese laid-open patent publication No. 5-201747 tends to embed many photocatalytic particles in the binder layer, so that no ultraviolet radiation will reach and no smelly gas or the like will contact those photocatalytic particles, which thus will fail to perform a sufficient photocatalytic function.
Anotruer known process of forming a photocatalytic layer is an alkoxide process disclosed in Japanese laid-open utility model publication No. 5-7394. According to the dis-closed process, a photocatalytic layer is formed by coating a base of glass with a titanium alkoxide, drying the coated titanium alkoxide, and thereafter firing the titanium alkox-ide at 100°C. ~~n organic material in water is decomposed when an ultraviolet radiation is applied to the photocata-lytic layer.
The a.lkoxide process is excellent in that it can form a thin film at a relatively low temperature, and is effective where a substance such as Pyrex glass or quartz glass which is not softened at temperatures up to about 500°C is used as the material of the base. If a substance such as soda glass having a low melting point is used as the material of a base, then the base is softened already at a temperature at 'which a thin film is formed, and a formed thin photocatalytic film is embedded in the base, with the result that no light will reach the photocatalytic layer, which will fail to perform photocatalytic functions.
According to Japanese laid-open patent publication No. 1-288321, a Ti02 sol is sprayed over ceramic paper of a fibrous material and thereafter heated at a temperature ranging from 400 to 700°C, and thereafter an Sn02 sol is sprayed and heated at a temperature ranging from 400 to 700°C, thus fon:ning a photocatalytic film capable of oxidiz-ing and decomposing aldehydes.
In the process disclosed in Japanese laid-open patent publication No. 1-288321, the entire surface of the film is covered with SnOz which is less active than TiOz, and attempts to increase the strength of the film are liable to cause cracks. Specifically, as shown in FIG. 1(a) of the accompanying drawings, when a sol containing Ti02 particles 101 is coated on the surface of a tile 100 and then heated (fired), a crack 102 develops as shown in FIG. 1(b) of the accompanying drawings. The crack is considered to occur because a phase transition to a rutile structure brings about a volume shrinkage (a density increase) and also be-cause whereas the distance between Ti02 particles 101 is Lo as shown in FIG. 2(a) of the accompanying drawings before being fired, the distance is reduced to L1 (Li < Lo) as shown in FIG. 2(b) of the accompanying drawings due to volumetric diffusion of the particles into each other after being ffired into the rutile structure.
Japanese patent publication No. 4-46609 discloses a method of purifying an odor in the air in the passenger's compartment of a vehicle by decomposing or modifying a smelly substance contained in the odor. Specifically, light is applied to a. solid semiconductor photocatalyst in which a metal or a metal oxide is carried by a semiconductor, and the air to be ~~urified in the passenger's compartment is brought into contact with the solid semiconductor photocata-lyst for decomposing or modifying the smelly substance con-tained in the c~or due to a photochemical reaction.
However, when a base with its surface coated with a photocatalyst. is used in contaminated water or an outer wall, dirt tends to be deposited on the photocatalyst owing to high-molecular substances, dust particles, and bacteria that are contained in the atmospheric air or water. Depend-ing on the type of the dirt, the photocatalytic function may be lowered by t:he deposited dirt.
One solution to the reduction in the photocata-lytic function due to deposited dirt is disclosed in Japa-nese patent publication No. 6-7905. Japanese patent publi-cation No. 6-7905 reveals a deodorizing apparatus comprising a photocatalyti.c layer of semiconductor, an ultraviolet lamp and a heater disposed in confronting relation to the photo-catalytic layer, and an air blower. The photocatalytic layer or the heater, or the photocatalytic layer and the heater are moved for sequentially heating the photocatalytic layer in its entirety. When the photocatalytic layer is heated to a temperature close to 400°C, dirt of high-molecular substances, dust particles, and the like is re-moved, and the photocatalytic layer is regenerated.
The above arrangement of regenerating the photo-catalytic layer is practically difficult to use on a member of an installation disposed inside a room. Therefore, a more radical solution is desired not to remove dirt depos-ited on the photocatalytic layer but to prevent dirt from being deposited on a photocatalytic layer or to prevent a photocatalytic layer from lowering its photocatalytic func-tion even with dirt deposited thereon.
Japanese patent publication No. 6-7906 shows a process of applying light with high ultraviolet intensity to a photocatalyst: to remove an odor in a home or a office.

~.~~~82~
With this process of applying light with high ultraviolet intensity, however, the odor is decomposed at a different rate depending on the structure of the photocatalyst. Fur-thermore, though the base which carries the photocatalyst has sufficient mechanical strength as the base is porous and impregnated with the photocatalyst according to the process disclosed in them publication, no sufficient mechanical strength will b<: achieved if the base is .~.:ade of a material which is not porous such as glazed tile or relatively dense ceramic.
Ti02 _~s available in different crystallized forms including anataae, brucite, and rutile. The anatase struc-ture is better :in photoactivity than the other crystallized forms. It has been reported in the magazine "Surface", 1987, vol. 25 tlhat the photoactivity of rutile Ti02 is im-proved by carrying a metal such as Pt, Ag, or the like.
However, rutile TiOz has no sufficient odor removal rate, density, and ad:hesiveness. If Ag or Ag0 is used as a metal to be added, than the resultant photocatalyst is not suit-able for use on tiles and building materials because these metals are black.
A sol of titanium oxide produced by the hydrother-mal method or the sulfuric acid method can easily be coagu-lated because it is composed of ultrafine particles. If the coagulated material is coated on the surface of a base, then it will cause gloss irregularities and cracks. For prevent-ing a sol of titanium oxide from being coagulated, it has 2I5~~~2 heretofore been customary to attach an organic dispersant such as of triethanolamine to the surface of the titanium oxide sol.
If a monodisperse titanium oxide sol with an or-ganic dispersant such as of triethanolamine being attached to the surface of the titanium oxide sol is coated on a base such as a resin base of low heat resistance and then fired and secured at 300°C, then since the organic dispersant is firmly fixed to the active sites of the titanium oxide sol and is not sufficiently evaporated and decomposed in the firing step, the resultant material exhibits no sufficient photocatalytic action, and has no sufficient deodorizing and antibacterial capabilities.
Japanese laid-open patent publication No. 5-253544 discloses a process of kneading anatase titanium oxide with a binder, coating the mixture on the surface of a base, and heating the coated base. According to the disclosed proc-ess, a binder layer is formed on the surface of a plate mem-ber serving as a wall surface, a floor surface, or a ceiling surface of a dwelling space, and then a fine powder of pho-tocatalyst made primarily of anatase titanium oxide is sprayed onto the surface of the binder layer such that the fine powder of photocatalyst is partly exposed from the binder layer. Thereafter, the binder layer is melted by being heated at. a temperature of 300°C or higher and lower than 900°C, after which the binder layer is cooled and so-lidified.

~15582~
The photocatalytic material produced according to this method has a good deodorizing ability if heat-treated at a temperature of 300°C or higher and lower than 900°C, but does not exlhibit good deodorizing characteristics at low temperatures lower than 300°C. Therefore, it has been dif-ficult to add a good photocatalytic activity such as excel-lent deodorizing characteristics to a base of plastic which is not resistant to heat. The reasons for this are consid-ered to be as fellows: In order to coat photocatalytic par-ticles uniformly on a base, it is necessary to produce, in a preceding step, a monodisperse system of such photocatalytic particles dispersed in the suspension with an organic dis-persant added. At temperatures lower than 300°C, the added organic dispersant is not sufficiently decomposed and vapor-ized and remains in covering relation to active sites on the photocatalytic ;particles.
Therefore, it is an object of the present inven-tion to provide a multi-functional material in which a pho-tocatalytic layer is exposed from a base to exhibit a suffi-cient photocatalytic effect, and the base well retains the photocatalytic layer.
Another object of the present invention is to form a photocatalytic layer which is less peelable on a rela-tively dense base of glass, tile, metal, or plastic.
Stil7. another object of the present invention is to form a photocatalytic layer on a base of relatively low - g _ 2I5~822 melting point, e.g., a base of soda glass which is rela-tively inexpensive and can easily be processed.
Yet ;till another object of the present invention is to provide a multi-functional material which is resistant to deposition of dirt thereon, has an antibacterial or de-odorizing capability that can prevent a function from being lowered due to dirt, and has an excellent mechanical strength.
A further object of the present invention is to provide a multi-functional material in which a photocata-lytic layer made principally of anatase Ti02 has an excellent peel strength.
A still further object of the present invention is to increase the photocatalytic activity of a photocatalytic layer which is made primarily of rutile Ti02.
A yet: still further object of the present inven-tion is to increase the photocatalytic activity of a photo-catalytic layer which is made primarily of rutile TiOz and decolorize the photocatalytic layer for better appearance by having the photocatalytic layer carry Ag.
Stil7. another object of the present invention is to provide a mu.lti-functional material having a good photo-catalytic function even if heated at low temperatures lower than 300°C.
DISCLOSURE OF THE INVENTION:
_ 9 _ A mul.ti-functional material according to the pres-ent invention comprises a photocatalytic layer formed on the surface of a base of ceramic such as tile, sanitary ware, or glass, or resin, metal, or wood directly or through a binder layer. The type of photocatalytic particles which make up the photocatalytic layer, the diameter of the photocatalytic particles, the interstices between the photocatalytic parti-cles, the porosity of the photocatalytic layer, the rela-tionship between the binder layer and the photocatalytic layer, particles that fill the interstices between the pho-tocatalytic particles, and metal particles fixed to the sur-faces of the photocatalytic particles are arranged to allow the multi-functional material to have excellent photocata-lytic effects, such as a deodorizing effect, of the photo-catalytic layer, and also excellent antibacterial and wear-resistant capabilities.
BRIEF DESCRIPTION OF THE DRAWINGS:
FIG. 1(a) is a view showing a conventional Ti02 sol before it i.s fired, FIG. 1(b) is a view showing the con-ventional TiOz ;sol after it is fired into a rutile structure;
FIG. 2(a) is a view showing conventional TiOz par-ticles before they is fired, FIG. 2(b) is a view showing the conventional Ti.OZ particles after they are fired;
FIG. 3 is a view of a multi-functional material having photocat.alytic functions according to the present invention, the view schematically showing the manner in which photocatalytic particles of a photocatalytic layer are joined by a potential energy;
FIG. 4 is a view of a multi-functional material having photocatalytic functions according to the present invention, schematically showing the manner in which photo-catalytic particles of a photocatalytic layer are joined by solid-state sintering;
FIG. 5 is a view of a multi-functional material having photocatalytic functions according to the present invention, schematically showing the manner in which small particles are filled in interstices between photocatalytic particles of a photocatalytic layer;
FIG. 6 is a view schematically showing the manner in which metal particles are fixed to the surfaces of photo-catalytic particles of the multi-functional material shown in FIG. 3;
FIG. 7 is a view schematically showing the manner in which metal particles are fixed to the surfaces of photo-catalytic particles of the multi-functional material shown in FIG. 4;
FIG. 8 is a view schematically showing the manner in which metal particles are fixed to the surfaces of photo-catalytic particles of the multi-functional material shown in FIG. 5;
FIG. 9 is a view of a multi-functional material having photocat:alytic functions according to the present invention, schs~matically showing the manner in which the 21~58?2 photocatalytic layer is joined to a base through a binder layer and photocatalytic particles of a photocatalytic layer are joined by a potential energy;
FIG. 10 is a view of a multi-functional material having photocatalytic functions according to the present invention, schematically showing the manner in which the photocatalytic layer is joined to a base through a binder layer and photocatalytic particles of a photocatalytic '_ayer are joined by solid-state sintering;
FIG. 11 is a view of a multi-functional material having photocatalytic functions according to the present invention, schematically showing the manner in which the photocatalytic layer is joined to a base through a binder layer and small particles are filled in interstices between photocatalytic particles of a photocatalytic layer;
FIG. 12 is a view schematically showing the manner in which metal particles are fixed to the surfaces of photo-catalytic particles of the multi-functional material shown in FIG. 9;
FIG. 13 is a view schematically showing the manner in which metal particles are fixed to the surfaces of photo-catalytic particles of the multi-functional material shown in FIG. 10;
FIG. 14 is a view schematically showing the manner in which metal particles are fixed to the surfaces of photo-catalytic particles of the multi-functional material shown in FIG. 11;

FIG. :15 is a view illustrative of a method of manufacturing a multi-functional material having photocata-lytic functions according to the present invention;
FIGS. 16(a) and 16(b) are enlarged views of TiOz particles;
FIGS. 17(a) through 17(c) are views illustrative of a sintering mechanism for Ti02 particles;
FIG. 18 is a graph showii:g the results of an anti-bacterial test;
FIG. :19 is a set of graphs showing the results of tests with respE~ct to the amounts of Cu which was carried when a drying step was included before being irradiated by a BLB lamp and whE~n no drying step was included before being irradiated by a BLB lamp;
FIG. 20 is a graph showing the relationship be-tween the amount: of CU that was carried and the amount of CU
that was coated;;
FIG. :21 is a view illustrative of a method of manufacturing a multi-functional material having photocata-lytic functions according to another embodiment of the pres-ent invention;
FIG. :22 is a graph showing the results of an anti-bacterial test;
FIG. 23 is a set of graphs showing the results of tests with respE~ct to the amounts of Cu which was carried when a drying step was included before being irradiated by a BLB lamp and when no drying step was included before being irradiated by a BLB lamp;
FIG. 24 is a graph showing the relationship be-tween the amount of CU that was carried and the amount of CU
that was coated;
FIG. 25 is a graph showing the relationship be-tween the amount of Ag that was carried and the bacteria survival ratic;
FIG. 26 is a diagram showing a basic profile of a section of a multi-functional material as it is observed by EBMA (electron-beam microanalyzer);
FIG. 27 is a diagram showing a basic profile of a section of a multi-functional material as it is observed by EBMA (electron-beam microanalyzer);
FIG. 28 is a graph showing the relationship be-tween the composition of TiOz and Sn02, the strength of a film, and the photoactivity;
FIG. 29 is a graph showing the relationship be-tween the heat-treatment temperature and the photoactivity;
FIG. 30 is a view illustrative of a process of measuring the activity of a thin photocatalytic film;
FIG. 31 is a view illustrative of a process of measuring the activity of a thin photocatalytic film;
FIG. 32 is a view illustrative of a process of measuring the activity of a thin photocatalytic film;
FIG. 33 is a graph showing the relationship be-tween the time of ultraviolet irradiation and the pH change;

FIG. 34 is a graph showing the relationship be-tween R3o and the pH change;
FIG. 35 is a graph showing the relationship be-tween the porosity, the deodorizing ability (R3o), and the wear resistance;;
FIG. 36 is a graph showing the relationship be-tween the film i~hickness and the deodorizing ability (R3o)%
FIG. 37 is a graph showing the relationship be-tween the film i:hickness, the deodorizing ability (R3o), and the peeling resistance;
FIG. 38 is a graph showing the relationship be-tween the amounts of Sn02 which was added, the deodorizing ability (R3o), a:nd the wear resistance;
FIG. 39 is a graph showing the relationship be-tween the amounit of Sn02 which was added and the difficulty with which dirt is deposited;
FIG. 40 is a graph showing the relationship be-tween the amount of SnOZ which was added and the percentage of open pores alt the surface of a Ti02 layer;
FIG. 41 is a graph showing the relationship be-tween the amount of Sn02 which was added and the width of open pores at tlhe surface of a TiOz layer;
FIG. 42 is a graph showing the relationship be-tween the amount of Sn02 which was added, the deodorizing ability R3o (L), and the peeling resistance;

~i558~~
FIG. 43 is a graph showing the relationship be-tween the numbEar of coatings and the difficulty with which dirt is deposited;
FIG. 44 is a graph showing the relationship be-tween the number of coatings and the wear resistance;
FIG. 45 is a graph showing the relationship be-tween the numbE~r of coatings and the percentage of open pores at the surface of a TiOZ layer;
FIG. 46 is a view showing the manner in which a ultrasonic radiation is applied to preferentially decompose and vaporize a thermosetting resin on photocatalytic parti-cles to expose the photocatalytic particles to the atmos-phere;
FIG. 47 is a view similar to FIG. 47, showing an-other embodiment;
FIG. 48 is a view similar to FIG. 47, showing still another Embodiment;
FIG. 49 is a set of views showing the manner in which small particles are filled in the interstice between photocatalytic particles;
FIG. 50 is a block diagram showing a process of manufacturing a multi-functional material made of rutile TiOz ;

FIG. 51 is a graph showing the relationship be-tween the concentration of a Cu solution and the photoaetiv-ity in the case where the Cu solution was photo-reduced when it was dried;
FIG. 52 is a graph showing the relationship be-tween the concentration of a Cu solution and the photoactiv-ity in the case where the Cu solution was photo-reduced when it was not dried;
FIG. 53 is a graph showing the relationship be-tween the concentration of a Cu solution and the odor re-moval ratio R3o when the metal carried on a thin film of ru-tile Ti02 was Cu (the metal ion was reduced after the aqueous solution of a metallic salt was dried);
FIG. 54 is a graph showing the relationship be-tween the concentration of a Cu solution and the odor re-moval ratio R~ when a base was a wall tile and the metal carried on a thin film of rutile TiOZ was Cu (the metal ion was reduced after the aqueous solution of a metallic salt was dried);
FIG. 55 is a graph showing the relationship be-tween the sintering temperature for producing a thin film of rutile TiOZ and odor removal ratio R~ after Cu was fixed;
FIG. 56 is a graph showing the relationship be-tween the concentration of an Ag and Cu solution and the color difference;
FIG. 57 is a graph showing the relationship be-tween the porosity, the R3a, and the wear resistance;
_. - 17 -FIG. 58 is a graph showing the relationship be-tween the amount of copper that was carried and the bacteria survival ratios;
FIG. 59 is a graph showing the relationship be-tween the amount of copper that was coated and the amount of copper that was carried;
FIG. 60 is a graph showing the relationship be-tween the amount of silver that was carried and the bacteria survival ratio;
FIG. 61 is a graph showing the relationship be-tween the amour.~t of silver that was carried and the color difference;
FIG. 62 is a graph showing the effect of a decol-orizing process using an aqueous solution of RI;
FIG. 63 is a graph showing the relationship be-tween the pH change in the aqueous solution of KI and the change of the odor removal ratio R3a after the decolorizing process using the aqueous solution of KI;
FIG. 64 is a graph showing a comparison of anti-bacterial capabilities;
FIG. 65 is a graph showing the wear resistance depending on the weight percentage of a tin oxide in a thin film;
FIG. 66 is a graph showing the photoactivity de-pending on the weight percentage of a tin oxide in a thin film;

~i558~2 FIG. 67 is a graph showing the wear resistance depending on the weight percentage of a tin oxide in a thin film in a comparative Inventive Example;
FIG. 68 is a graph showing the photoactivity de-pending on the weight percentage of a tin oxide in a thin film in a comparative Inventive Example; and FIG. 69 is a graph showing the relationship be-tween the amount of silver that was carried and the bacteria survival ratio.
BEST MODE FOR CARRYING OUT THE INVENTION:
The present invention will be described in greater detail with reference to the accompanying drawings.
FIGS.. 3 through 14 show the structures of multi-functional materials having photocatalytic functions accord-ing to the present invention, as they are divided into dif-ferent types. Any of the multi-functional materials having photocatalytic functions according to the present invention belongs to either one of these structures.
A mul.ti-functional material shown in FIG. 3 com-prises a photocatalytic layer 2 having photocatalytic func-tions which is directly disposed on the surface of a base 1.
The photocatalytic layer 2 is composed of fine photocata-lytic particles 3 joined together by a potential energy such as a surface energy, a curved-surface energy, or the like.
A multi-functional material shown in FIG. 4 com-prises a photoc,atalytic layer 2 having photocatalytic func-tions which is directly disposed on the surface of a base 1.
The photocatalyl:ic layer 2 is composed of photocatalytic particles 3 joined together by solid-state sintering.
A mufti-functional material shown in FIG. 5 com-prises a photocatalytic layer 2 having photocatalytic func-tions which is directly disposed on the surface of a base 1.
The photocatalyi:ic layer 2 is composed of photocatalytic particles 3 joined together bj particles 4 that fill inter-stices between ~~he photocatalytic particles 3 and smaller than the intersi~ices .
In FIG. 5, the particles 4 are shown as filling those intersticE;s which are positioned inside the photocata-lytic layer 2. However, the particles 4 may fill those in-terstices betweE~n the photocatalytic particles 3 in at least a surface layer" Specifically, since the bonding of the photocatalytic particles 3 in the surface layer is important for the mechani<:al strength of the photocatalytic layer 2 as external forces transmitted thereto is attenuated inside the photocatalytic 7Layer 2, only the interstices between the photocatalytic particles 3 in the surface layer may be filled with the fine particles 4. In such a case, the pho-tocatalytic pari:icles 3 inside the photocatalytic layer 2 are joined togei:her by a potential energy, and the photo-catalytic particles 3 should preferably have an average di-ameter of 0.04 ~tm for the photocatalytic layer 2 to achieve a sufficient mechanical strength.

A mul-ti-functional material shown in FIG. 6 com-prises a photocatalytic layer 2 directly disposed on the surface of a base 1. The photocatalytic layer 2 is composed of photocatalytic particles 3 joined together by a potential energy, and elecaron-capturing particles 5 such as of Ag, Cu, CuzO, or the like fixed to the surfaces of the photocata-lytic particles 3.
A multi-functional material shown in FIG. 7 com-prises a photocatalytic layer 2 directly disposed on the surface of a base 1. The photocatalytic layer 2 is composed of photocatalytic particles 3 joined together by solid-state sintering, and metal particles 5 such as of Ag, Pt, or the like fixed to the surfaces of the photocatalytic particles 3.
A multi-functional material shown in FIG. 8 com-prises a photocatalytic layer 2 having photocatalytic func-tions which is directly disposed on the surface of a base 1.
The photocatalyt:ic layer 2 is composed of photocatalytic particles 3 joined together by particles 4 that fill inter-stices between t:he photocatalytic particles 3 and smaller than the interstices, and metal particles 5 such as of Ag, Pt, or the like fixed to the surfaces of the photocatalytic particles 3.
A mufti-functional material shown in FIG. 9 com-prises a photocatalytic layer 2 having photocatalytic func-tions which is disposed on the surface of a base 1 through a binder layer 6. The photocatalytic layer 2 has a surface .~ 215x822 layer exposed to the exterior and a lower layer embedded in the binder layer: 6, the surface layer being composed of fine photocatalytic particles 3 joined together by a surface en-ergy.
A mufti-functional material shown in FIG. 10 com-prises a photocatalytic layer 2 disposed on the surface of a base 1 through a binder layer 6. The photocatalytic layer 2 has a surface layer composed of photocatalytic particles 3 joined together by solid-state sintering.
A muhti-functional material shown in FIG. 11 com-prises a photocatalytic layer 2 disposed on the surface of a base 1 through a binder layer 6. The photocatalytic layer 2 is composed of F>hotocatalytic particles 3 joined together by particles 4 that; fill interstices between the photocatalytic particles 3 and smaller than the interstices.
A muli~i-functional material shown in FIG. 12 com-prises a photocatalytic layer 2 disposed on the surface of a base 1 through a binder layer 6. The photocatalytic layer 2 is composed of photocatalytic particles 3 joined together by a potential energy, and electron-capturing particles 5 such as of Ag, Cu, Cu~20, or the like fixed to the surfaces of the photocatalytic particles 3.
A muli:i-functional material shown in FIG. 13 com-prises a photoca~talytic layer 2 disposed on the surface of a base 1 through a~ binder layer 6. The photocatalytic layer 2 is composed of photocatalytic particles 3 joined together by solid-state sintering, and electron-capturing particles 5 such as of Ag, (:u, Cu20, or the like fixed to the surfaces of the photocatalyi;ic particles 3.
A mufti-functional material shown in FIG. 14 com-prises a photocatalytic layer 2 disposed on the surface of a base 1 through a binder layer 6. The photocatalytic layer 2 is composed of photocatalytic particles 3 joined together by particles 4 that: fill interstices between the photocatalytic particles 3 and smaller than the interstices, and metal par-ticles 5 such as of Ag, Pt, or the like fixed to the sur-faces of the photocatalytic particles 3.
The base 1 in each of the above multi-functional materials may bE~ made of ceramic such as tile, sanitary ware, or glass, or resin, metal, wood, or a compound of some of these materials.
The p:hotocatalytic particles 3 are semiconductor particles having a sufficient band gap to perform photocata-lytic functions including an antibacterial function, a de-odorizing function, etc. According to one theory, photo-catalytic parti<:les are antibacterial because bacteria are electrocuted whE~n a voltage higher than a certain voltage is applied. Generally, however, photocatalytic particles are antibacterial due to active oxygen produced when irradiated with light for l,he same reason that photocatalytic particles are deodorizing.. For producing active oxygen, it is neces-sary that one conduction band of a semiconductor as it is represented by a band model be positioned higher than a hy-drogen generating potential and an upper end of a valence 215~~22 band be positioned lower than an oxygen generating poten-tial. Semiconductors which satisfy such requirements in-clude TiOz, SrTi.03, ZnO, SiC, gallium phosphide, CdS, CdSe, MoS3, etc. Since the position of the conduction band moves upwardly when converted into fine particles, fine particles of Sn02, W03, Fe;,03, Bi203, etc. which have a diameter ranging from 1 to 10 nm are possibly capable of generating active oxygen. Particularly preferable among these materials is anatase Ti02 because it can be processed into fine particles that are chemically stable and highly active which can be produced inexpensively.
The electron-capturing particles are those parti-cles which capture electrons when electrons and holes are produced upon exposure of the photocatalytic particles to light and prevent the electrons from being re-combined with the holes. MatE:rials of the electron-capturing particles include Ag, Cu, Pt, Pd, Ni, Co, Fe, Cu20, etc.
The binder layer 6 is made of a thermoplastic ma-terial such as Blaze, inorganic glass, thermoplastic resin, solder, or the like. With the binder layer 6 being made of a thermoplastic material, a photocatalyst can be coated on the binder layer at normal temperature by a simple and inex-pensive process such as spray coating or the like, and the base 1, the binder layer 6, and the photocatalytic layer 2 can be joined strongly only by heating, resulting in an ad-vantage with re~~pect to the manufacturing cost.

A mufti-functional material having photocatalytic functions according to the present invention is composed of a photocatalytic: layer composed of photocatalytic particles which is laminai:ed to or partly embedded in a sheet-like binder layer made of a thermoplastic material. If such a sheet-like mult~L-functional material is applied to an exist-ing tile, sanitary ware, a building material, or the like and thereafter treated, then the existing tile or the like is given added funcaions including a deodorizing function, a stain-resistant function, an antibacterial function, a bac-tericidal function, and a mildew-resistant function.
The amperage diameter of the photocatalytic parti-cles 3 of the photocatalytic layer 2 should preferably be smaller than O.a N.m for increasing the specific surface area for higher photocatalytic activity.
The thickness of the photocatalytic layer 2 should preferably be in the range from 0.1 dun to 0.9 dun. If the thickness of they photocatalytic layer 2 were smaller than 0.1 ~tm, then photocatalytic particles would be embedded in localized areas of the binder layer 6, creating regions on the surface of the multi-functional material which would fail to exhibit photocatalytic activity. Since bacteria would tend to beg trapped by those regions, the antibacterial capability of th.e multi-functional material would be low-ered. If thickness of the photocatalytic layer 2 were greater than 0.f dun, then it would suffer large thickness variations, making it difficult for stains deposited on sam-ples to be detached. The thickness of the photocatalytic layer 2 extends from the outermost surface of the thin pho-tocatalytic film to the portion thereof that is embedded in the lower layer of glaze, and is measured by conducting an elementary analysis with EBMA (electron-beam microanalyzer) and determining the distance to the outermost surface from an uppermost portion of a region where major constituent elements of the glaze layer that have increased are substan-tially constant..
A design effect can be achieved by varying the thickness of them photocatalytic layer 2. Specifically, if the thickness oj' the photocatalytic layer 2 is equal to or higher than 0.2 Eun, but smaller than 0.4 Eun, then the photo-catalytic layer 2 is given a rainbow-like pattern due to light interference on thicker portions of the photocatalytic layer 2. For producing an appearance composed of only the color of the base, the pattern thereof, or a combination thereof, thicken portions of the photocatalytic layer 2 whose thickness is equal to or higher than 0.1 ~tm, but smaller than 0 . ~! ~tm, or equal to or higher than 0 . 4 Etm, but smaller than 1 ~.un, may be formed in regions except for re-gions where the above light interference is caused. Such an arrangement is applicable to a wide range of applications including tiles, basins, bathtubs, closet bowls, urinals, sinks, cooking gables, etc.
If them photocatalytic particles 3 only are joined together, then only a potential energy (adsorption) between 2I55~22 them or sintering is available to join them together. If the photocatalytic particles are to be sintered, they have to be fired at .a considerably high temperature. If the pho-tocatalytic particles are to be adsorbed to each other, they will not be joined sufficiently and the active sites thereof will be consumed by the adsorption unless the specific sur-face area of the photocatalytic particles are substantially large and the falling capability thereof is high. There-fore, there are limitations on the process of manufacturing a multi-functional material having sufficient catalytic ac-tivity and wear--resistance.
If particles greater than the interstices between the photocatalyi~ic particles 3 were employed in an attempt to increase the bonding between the photocatalytic particles 3, no sufficient: bonding forces would be available, and the photocatalytic particles exposed on the surface of the multi-functional. material would be covered. The surface of the multi-functional material would have areas where no catalytic activity would be exhibited, and bacteria would be trapped, with the result that the antibacterial function of the multi-functional material would be greatly reduced.
An in~:erstice between photocatalytic particles represent both a~ neck between photocatalytic particles 3 as shown in FIG. 1f.(a) and a pore between photocatalytic parti-cles 3 as shown in FIG. 16(b). Particles 4 having a diame-ter smaller than. such an interstice between photocatalytic particles are particles smaller than either the neck between w 215822 photocatalytic particles or the pore between photocatalytic particles, whichever is greater. The particles 4 are par-ticularly effective in joining the photocatalytic particles to each other in the structure shown in FIG. 16(b).
The small particles 4 that fill the interstices between the phot:ocatalytic particles 3 are basically not limited to any material, but should be of materials of high adsorbing power. If the small particles 4 were made of a material having extremely small adsorbing forces, then they would not serve the purpose of joining photocatalytic parti-cles. If the small particles 4 were made of a material hav-ing extremely large adsorbing forces, then they would be more likely to cover active sites on the surfaces of photo-catalytic particles than to enter the interstices between photocatalytic particles. In view of this, the particles 4 that fill the interstices between the photocatalytic parti-cles 3 should preferably be made of any of metals including Sn, Ti, Ag, Cu, Zn, Fe, Pt, Co, Pd, Ni, or the like or their oxides. However, zeolite, active carbon, clay, or the like which has heretofore been used as an adsorption carrier is not preferable a.s the material of the particles 4. Of the above metals and oxides, tin oxide is preferable in that it has adequate adsorbing power. Since metals or oxides of Ag, Cu, or the like have their own antibacterial and deodorizing capabilities other than their capacity to join photocata-lytic particles, they are preferable for use in assisting the action of a photocatalyst in the absence of light irra-diation in applications where their antibacterial and de-odorizing capabilities are required. Consequently, the metal particles 5 may be used as the small particles 4 that fill the interstices between the photocatalytic particles 3.
The particles 4 that fill the interstices between the photocatalyt.ic particles 3 should preferably have an average diameter which is 4/5 or less of the average diame-ter of the photocatalytic particles 3.
According to the presently available fabrication process, the particles 4 that fill the interstices between the photocatalytic particles 3 not only enter the intersti-ces between the photocatalytic particles 3, but also are attached to the photocatalytic particles 3 to some extent.
If the diameter of the particles that fill the interstices were in excess of 4/5 of the average diameter of the photo-catalytic particles, then it would be more likely for the particles 4 to be attached to the surfaces of the photocata-lytic particles than to enter the interstices between the photocatalytic particles, resulting in a reduction in the bonding strength of the photocatalytic particles 3. If the particles that fill the interstices were greater than the photocatalytic particles, then they would partly cover the photocatalytic particles, creating regions on the surface of the multi-functional material which would fail to exhibit photocatalytic activity. Since bacteria would tend to be trapped by those regions, the antibacterial capability of the multi-functional material would be lowered.

__ 215~~22 The average diameter of the particles 4 that fill the interstices between the photocatalytic particles 3 should preferably be less than 0.01 ~tm for increasing their specific surfaced area to produce adequate adsorbing forces.
The amount of the particles 4 that fill the inter-stices between t:he photocatalytic particles 3 with respect to the total amount of the photocatalytic particles 3 and the filling particles 4 should preferably be of a molar ra-tio ranging from 10 % to 60 %. When a photocatalytic layer is fixed to a base through a binder layer by heating the photocatalytic 7_ayer in a temperature range which is low enough not to sinter photocatalytic particles, if the amount of particles that fill interstices were too small, then the photocatalytic F>articles would not be firmly joined to-gether, and if t:he amount of particles that fill interstices were too large, then the amount of particles covering the photocatalytic particles would be increased, creating re-gions on the surface of the multi-functional material which would fail to e~:hibit photocatalytic activity. Since bacte-ria would tend t:o be trapped by those regions, the antibac-terial capability of the multi-functional material would be lowered. Therefore, the molar ratio in the range from 10 %
to 60 % is prefE~rable.
The m~3terial of the particles 4 that fill the in-terstices betweE~n the photocatalytic particles 3 should preferably be of: a vapor pressure that is higher than the vapor pressure of the material of the photocatalytic parti-21~~~22 cles 3, so that the particles 4 that fill the interstices between the pho~~ocatalytic particles 3 will be agglomerated at the necks bei~ween the photocatalytic particles 3. This is because it is better for the particles 4 to be sintered rather than being filled only for joining the photocatalytic particles 3 morel firmly thereby to increase the peel strength of the photocatalytic layer. If such a material haling a high vapor pressure is selected as the material of the particles 4 that fill the interstices, then it will also serve as a sintE~ring additive to lower the sintering tem-perature.
Materials having a high vapor pressure include tin oxide, bismuth oxide, zinc oxide, or the like, but tin oxide is preferable from the standpoint of safety.
The layer containing the particles 4 that fill the interstices between the photocatalytic particles 3 should preferably have a thickness of 0.1 Etm or greater. If the thickness of this layer were smaller than 0.1 Eun, then the photocatalytic particles (or particles that fill the inter-stices depending on the manufacturing process) would be em-bedded in localized areas of the binder layer 6, creating regions on the :surface of the multi-functional material which would fai7_ to exhibit photocatalytic activity. Since bacteria would tend to be trapped by those regions, the an-tibacterial capability of the multi-functional material would be lowered. The thickness of the layer containing the particles 4 that: fill the interstices between the photocata-21~~~22 lytic particles 3 extends from the outermost surface to a portion embedded in a lower layer of the binder, the thick-ness covering averaged surface irregularities.
FIG. :l5 is illustrative of a method of manufactur-ing a multi-functional material having photocatalytic func-tions according to the present invention. According to the present invention, a base 1 is prepared as shown in FIG.
15(a), and then a binder layer 6 is formed on the surface of the base 1 as shown in FIG. 15(b). The binder layer 6 is made of a material whose softening temperature is lower than the softening temperature of the base 1. For Inventive Ex-ample, if the base 1 is a tile, an enameled member, or a pottery product, then the binder layer 6 may comprise a glazed layer or .a printed layer thereon.
Then, as shown in FIG. 15(c), a photocatalytic layer 2 composed of photocatalytic particles such as TiOz particles or the like is formed on the binder layer 6. At this time, the plhotocatalytic layer 2 may be placed on the binder layer 6 with bonding forces just enough to keep the photocatalytic 1<iyer 2 on the binder layer 6 in a subsequent sintering step.
Alternatively, before the binder layer 6 is formed on the surface oi= the base 1, a photocatalytic layer 2 may be formed on the binder layer 6 as shown in FIG. 15(b~), and then the binder layer 6 may be placed on the base 1.
Therea:Eter, the assembly is heated at an atmos-pheric temperature which is higher than the softening tem-zmJgz2 perature of the binder layer 6 by a temperature higher than 20°C but lower than 320°C and which is lower than the sof-tening temperature of the base 1. Now, as shown in FIG.
15(d) or FIGS. 5i through 14, a lower layer of the photocata-lytic layer 2 close to the binder layer 6 is partly settled into the binder layer 6 and embedded in and firmly held by the binder layer 6 when the binder layer 6 is solidified.
Some of those photocatalytic particles 3 of the photocata-lytic layer 2 which constitute a surface layer exposed to the ambient air are joined to each other as shown in FIG.
16(a} by a potential energy, intermolecular forces, or sin-tering, and the other of those photocatalytic particles 3 remain separate from each other as shown in FIG. 16(b).
Therefore, the surfaces of the photocatalytic particles are exposed to the exterior substantially at the surface layer.
The temperature at which the assembly is heated is higher than the softening temperature of the binder layer 6 by a temperature higher than 20°C but lower than 320°C be-cause if lower than 20°C, then it takes time for the binder layer to be softened and the photocatalytic particles 3 would not sufficiently be retained, and if higher than 320°C, then the binder layer would quickly be melted, allow-ing the photocat~alytic particles 3 to be embedded in the binder layer, pr~~ducing surface irregularities, and giving rise to breaks and pinholes. Preferably the temperature at which the assembly is heated should be higher than the sof--~ 2155822 tening temperature of the binder layer 6 by a temperature which is at least 40°C but at most 300°C.
If it is assumed that the specific gravity of the photocatalytic particles 3 is represented by 8t and the spe-cific gravity o:E the binder layer 6 by 8b, then these spe-cific gravities should fall in the range of 0 <_ $t - 8b s 3.0, preferably 0.5 < $t - bb s 2Ø If the difference be-tween the specijFic gravities of the photocatalytic particles 3 and the binder layer 6 were too small, then when the binder layer 6 ~Ls melted, the speed of vertical travel of the photocatalyt:ic particles 3 in the binder layer 6 would be low, allowing the photocatalytic particles 3 to be peeled off easily after. sintering. If the difference between the specific gravities of the photocatalytic particles 3 and the binder layer 6 were too large, the speed of vertical travel of the photocata~lytic particles 3 in the binder layer 6 would be high, allowing most of the photocatalytic particles 3 to be embedded. in the binder layer 6. If such a condition were localized, then bacteria would be trapped at the bottom of the localized area, and the antibacterial capability would be lowered.
In cables which require the specific gravities to be in the range of 8t - 8b > 3.0, a second binder layer which meets the requirement: 0 _< St - bb < 3.0 may be interposed between the binder layer 6 and the photocatalytic particles 3.

_0 2155$22 If bt - 8b < 0, then the specific gravity differ-ence 8t - 8b may be increased by pressing the assembly when it is heated. Therefore, the same advantages as those when the range of 0 ~ 8t - 8b s 3.0 is met are obtained by a HIP
process or a hot pressing process.
The interstices between the photocatalytic parti-cles which make up a portion exposed from the binder layer 6, specifically the neck between the photocatalytic parti-cles shown in FIG. 16(a) or the interstice between the pho-tocatalytic particles shown in FIG. 16(b), may be filled with particles 4, which are made of any of metals including Sn, Ti, Ag, Cu, Zn, Fe, Pt, Co, Pd, Ni, or the like or their oxides, having a diameter smaller than the interstices to join the photocatalytic particles to each other.
In another method of manufacturing a multi-functional material having photocatalytic functions accord-ing to the present invention, a binder layer 6 made of a thermoplastic material is formed on a base 1 of ceramic, resin, metal, or the like, and then a mixture in the form of a sol or precursor composed of photocatalytic particles 3 and particles 4 smaller in diameter than the photocatalytic particles 3 is coated on the binder layer 6, thus producing a photocatalytic layer 2. Thereafter, the binder layer 6 is softened to allow a lower layer of the photocatalytic layer 2 to be partly embedded in the binder layer 6, and is then solidified.

The above method is simple to carry out, and can easily control t:he mixture ratio of the photocatalytic par-ticles 3 and thEa particles 4 which fill the interstices therebetween because the photocatalytic layer 2 is formed by coating a mixture in the form of a sol or precursor composed of particles 4 f:or filling interstices and photocatalytic particles 3.
In stall another method of m~:aufacturing a multi-functional material having photocatalytic functions accord-ing to the presE~nt invention, a mixture in the form of a sol or precursor composed of photocatalytic particles 3 and par-ticles 4 smaller in diameter than the photocatalytic parti-cles 3 is coated on a sheet-like binder layer 6 made of a thermoplastic material, thus producing a photocatalytic layer 2. Then, the binder layer 6 with the photocatalytic layer 2 formed thereon is placed or bonded to a base 1 of ceramic, resin, metal, or the like. Thereafter, the binder layer 6 is softened to allow a lower layer of the photocata-lytic layer 2 to be partly embedded in the binder layer 6, and is then solidified.
In yet: still another method of manufacturing a multi-functional material having photocatalytic functions according to the present invention, a binder layer 6 made of a thermoplastic material is formed on a base 1 of ceramic, resin, metal, or the like, and then a photocatalytic layer 2 composed of photocatalytic particles 3 is formed on the binder layer 6. Thereafter, the binder layer 6 is softened 215~~?2 to allow a lower layer of the photocatalytic layer 2 to be partly embedded in the binder layer 6, and is then solidi-fied. Furthermore, a solution containing small particles is coated on the photocatalytic layer 2, and then the assembly is heated to fix small particles 4 to the photocatalytic particles 3.
The above method is relatively easy to carry out if the particle:. that fill the interstices are made of an oxide, and allows many particles to be attached to fill the interstices if t:he photocatalytic layer is relatively po-rous.
In a :Further method of manufacturing a multi-functional material having photocatalytic functions accord-ing to the present invention, a photocatalytic layer 2 com-posed of photoca:talytic particles 3 is formed on a sheet-like binder layer 6 made of a thermoplastic material, and then the sheet-like binder layer 6 with the photocatalytic layer 2 formed thereon is placed on or bonded to a base 1 of ceramic, resin, metal, or the like. Thereafter, the binder layer 6 is softened to allow a lower layer of the photocata-lytic layer 2 to~ be partly embedded in the binder layer 6, and is then solidified. Furthermore, a solution containing metal particles 4 is coated on the photocatalytic layer 2, and then the assembly is heated to fix small particles to the photocatalytic particles 3.
In a :still further method of manufacturing a multi-functional material having photocatalytic functions 2155~~2 according to the present invention, a binder layer 6 made of a thermoplastic material is formed on a base 1 of ceramic, resin, metal, or the like. Then, a photocatalytic layer 2 composed of photocatalytic particles 3 is formed on the binder layer 6. Thereafter, the binder layer 6 is softened to allow a lower layer of the photocatalytic layer 2 to be partly embedded in the binder layer 6, and is then solidi-fied. Furthermore, a solution containing ions of small metal particles 4 is coated on the photocatalytic layer 2, and then irradiated with light including ultraviolet rays to reduce the metal ions, thereby fixing the metal particles 4 to the photocatalytic particles 3.
The at~ove method is relatively easy to carry out if the particles that fill the interstices are made of metal, and can fix the metal particles in a highly short period of time, i.e., in several minutes. A lamp for apply-ing ultraviolet rays may be an ultraviolet lamp, a BLB lamp, a xenon lamp, a mercury lamp, or a fluorescent lamp.
In a ~~et still further method of manufacturing a multi-functional material having photocatalytic functions according to the present invention, a photocatalytic layer 2 composed of photocatalytic particles 3 is formed on a sheet-like binder layer 6 made of a thermoplastic material, and then the sheet-like binder layer 6 with the photocatalytic layer 2 formed thereon is placed on or bonded to a base 1 of ceramic, resin, metal, or the like. Thereafter, the binder layer 6 is softened to allow a lower layer of the photocata-._ 2I558~2 lytic layer 2 to be partly embedded in the binder layer 6, and is then sol_~dified. Furthermore, a solution containing ions of small mE;tal particles 4 is coated on the photocata-lytic layer 2, and then irradiated with light including ul-traviolet rays 1.o reduce the metal ions, thereby fixing the metal particles 4 to the photocatalytic particles 3.
In another method of manufacturing a multi-functional material having photocatalytic functions accord-ing to the presE~nt invention, a binder layer 6 made of a thermoplastic m~~terial is formed on a base 1 of ceramic, resin, metal, or the like. Then, a photocatalytic layer 2 composed of phoi;ocatalytic particles 3 is formed on the binder layer 6. Thereafter, a solution containing ions of small metal pari:icles 4 is coated on the photocatalytic layer 2, and thE~n irradiated with light including ultravio-let rays to reduce the metal ions, thereby fixing the metal particles 4 to i:he photocatalytic particles 3. Furthermore, the binder layer 6 is softened to allow a lower layer of the photocatalytic 7Layer 2 to be partly embedded in the binder layer 6, and is then solidified.
The albove method offers a higher productivity be-cause its heating step is carried out only once.
In still another method of manufacturing a multi-functional matei:ial having photocatalytic functions accord-ing to the presE:nt invention, a photocatalytic layer 2 com-posed of photocatalytic particles 3 is formed on a sheet-like binder layEar 6 made of a thermoplastic material, then a solution containing ions of small metal particles 4 is coated on the plZOtocatalytic layer 2, and irradiated with light including ultraviolet rays to reduce the metal ions, thereby fixing ithe metal particles 4 to the photocatalytic particles 3. F»rthermore, the sheet-like binder layer 6 with the photoc<~talytic layer 2 formed thereon is placed on or bonded to a base 1 of ceramic, resin, metal, or the like.
Thereafter, the binder layer 6 is softened to allow a lower layer of the photocatalytic layer 2 to be partly embedded in the binder layer_ 6, and is then solidified.
The photocatalytic particles 3 may be made of ZnO, and the metal p<~rticles 4 that fill the interstices between the photocatalyi~ic particles 3 may be made of Ag or Ag20.
The particles o7E Ag or Ag20 are effective not only to strengthen the <:oupling between the photocatalytic particles 3 of ZnO, but a_Lso to promote the photocatalytic effect of Zn0 and to perform antibacterial and deodorizing functions.
Zn0 selected as a photocatalytic material can eliminate col-oring by Ag ions, thus increasing a design effect produced by the color of the base, the pattern thereof, or a combina-tion thereof.
Alternatively, a solution containing salts which will form an insoluble colorless or white salt with ions of metal that fill the interstices between the photocatalytic particles may bE: held in contact with the photocatalytic layer, and therE~after irradiated with light including ultra-violet rays.

.~ 2I5~822 With the above process, it is possible to elimi-nate coloring b~~ the particles that fill the interstices, without resorting to a combination of Zn0 and Ag or Ag20, thereby increasing a design effect produced by the color of the base, the pattern thereof, or a combination thereof.
The photocatalytic particles 3 may be made of Ti02, and the heat-treatment temperature at which the binder layer 6 is softened may be in the range of from 800°C to 1000°C. At a tE:mperature of 800°C or higher, the bonding strength of the TiOz particles is increased because necks are produced between the Ti02 particles in an initial sintering phase. At a temperature in excess of 1000°C, however, the sintering process would enter an intermediate sintering phase, and the photocatalytic layer would tend to crack as it would suffer an undue volume shrinkage owing to solid-state sintering of Ti02.
Alternatively, the photocatalytic particles 3 may be made of Ti02, the particles 4 that fill the interstices between the pho~:ocatalytic particles 3 may be made of Ag, and the solution containing salts which will form an insolu-ble colorless or white salt with Ag ions may be an aqueous solution of a halide such as RI, RC1, FeCl3, or the like.
Since Ag forms an insoluble colorless or white salt such as AgI, AgCl, or the like with an alkali halide, a design ef-fect produced bar the color of the base, the pattern thereof, or a combination thereof can be increased.

If a dispersing step is included prior to the step of coating phot.ocatalytic particles on a binder layer, then a dispersant for dispersing a sol or precursor which will become photocat.alytic particles in the dispersing step should preferably be composed of only a component which will be vaporized at. a temperature lower than the heat-treatment temperature at which the binder layer will be softened.
Heretofore, no deodorizing capability has been available at a temperature lower than 320°C because a dis-persant attached to the surfaces of Ti02 particles in the dispersing step is not sufficiently vaporized and evapo-rated, and hence the surfaces of TiOz particles have not suf-ficiently been exposed on the outermost surface of the base, resulting in an insufficient photocatalytic function. The dispersant which will be vaporized at a temperature lower than the heat-treatment temperature should preferably be an organic dispersant or a dispersant of phosphoric acid whose molecular weight is ten thousands or less.
(Inventive Example 1) After a binder layer composed of SiOZ-A1203-Na/Rz0 frit was formed on the surface of a base in the form of a square pottery tile with each side 150 mm long by spray coating and then dried, an aqueous solution of 15 % of TiOz sol was coated on the binder layer by spray coating, forming a Ti02 layer having a thickness of 0.8 ~tm. Then, the base with the binder layer and the TiOz layer formed thereon was heated at different atmospheric temperatures for respective specimens by a roller-hearth kiln, and thereafter cooled and solidified into a multi-functional material.
The a<~ueous solution of 15 % of TiOz sol was pro-duced by hydrolyzing TiCl, for Inventive Example, in an autoclave under a hydrothermal condition ranging from 100 to 200°C to produce anatase Ti02 having a crystal diameter rang-ing from 0.007 to 0.2 ~tm, and dispersing several to several tens % of the anatase TiOZ in a sol state in an acid aqueous solution such as of nitric acid, hydrochloric acid or the like, or a basic' aqueous solution such as of ammonia or the like. To increase the dispersibility of the anatase Ti02, there was added 0.5 % or less of a surface treating agent of an organic acid salt such as triethanolamine or trimethylo-lamine, pentaerythritol, trimethylolpropane, or the like.
The particle diameters of the TiOZ sol were calculated based on image processing on SEM observations, and the crystal diameter was calculated from the integration width of powder X-ray diffraction.
While the spray coating was employed to coat the aqueous solution, it may be coated by dip coating or spin coating.
The produced multi-functional material was evalu-ated for antibacterial and wear-resistant capabilities.
With respect to the antibacterial capability, the multi-functional. material was tested for its antibacterial ability against escherichia coli, strain: W3110. Specifi-cally, 0.15 ml (;1 - 5 x 10' CFU) of the bacterial solution 215~~22 was dropped onto the outermost surface of the multi-functional material which had been sterilized with 70 ~
ethanol, and a glass sheet (10 x 10 cm) was placed in inti-mate contact with the outermost surface of the base, thus preparing a specimen. After the specimen was irradiated with light from .a white-light lamp with 3500 luxes for 30 minutes, the bacterial solution on the irradiated specimen and the bacter=a:L solution on a specimen kept under a shielded condition were wiped with a sterile gauze, and col-lected in 10 ml of physiological saline. The survival rates of the bacteria were determined as indications for evalua-tion.
The multi-functional material was tested for its wear resistance by rubbing it with a plastic eraser, and any change in the ap~aearance thereof was compared and evaluated.
Changes in the antibacterial and wear-resistant capabilities of specimens of the multi-functional material whose base was a pottery tile and binder was SiOZ-A1z03-Na/K20 frit as the firing temperature varied are given in Table 1 below.
(Table 1) Base = pottery tile, binder = Si02-A1z03-Na/R20 frit, photocatal~,rst = TiO, No. 1 2 3 4 5 Firing temperature (C) 700 780 880 980 1000 Difference with softening 20 100 200 300 320 temperature ( C ) Antibacterial capability ++ +++ +++ - _ Wear resistance O O O O O

+++: Survival rate of escherichia coli: less than 10 %
++ : Survival rate of escherichia coli: 10 % or more and less than 30 %
+ . Survival rote of escherichia coli: 30 % or more and less than ',70 %
- : Survival rate of escherichia coli: 70 % or more O . Not varied after 40 reciprocating rubbing movements against them specimens .
O . Damage was caused and the photocatalytic layer (Ti02 layer) was peeled off by 10 - 40 rubbing movements against the specimens.
D . Damage was caused and the photocatalytic layer (Ti02 layer) was peeled off by 5 - 10 rubbing movements against ths~ specimens .
x . Damage was caused and the photocatalytic layer (Ti02 layer) was peeled off by 5 rubbing movements or less against them specimens .
The Si02-A120,-Na/Kz0 frit used as the binder had a specific gravity of 2.4, a coated film thickness of 200 ~.tm, and a softening temperature of 680°C. The Ti02 in Table 1 had an anatase structure and a specific gravity of 3.9 for the specimens No~s. 1 - 3, and a rutile structure and a spe-cific gravity of 4.2 for the specimens Nos. 4 and 5.
In Tat>le 1, since the firing temperature of the specimen No. 1 was only 20°C higher than the softening tem-perature of the binder, so that the viscosity of the binder was not made sufficiently low, the anatase Ti02 particles which made up the lowermost layer of the photocatalytic layer were not sufficiently embedded in the binder layer.
As a result, the photocatalytic layer was damaged and peeled off by 5 - 10 rubbing movements against the specimens in the wear resistance test. With respect to the antibacterial capability, since the photocatalytic layer was made of ana-tase Ti02 which is of good photocatalytic activity and the organic component of the Ti02 sol was decomposed and vapor-ized based on TG-DTA observations at a temperature of 300°C
or higher, the dispersant such as a surface-treating agent or the like atta~~hed to the surface of the Ti02 layer was considered to be vaporized. As the firing temperature was 700°C much higher than the vaporizing temperature, the anti-bacterial capability had an excellent value of ++.
The durability of each of the specimens Nos. 3 -5, which had a firing temperature ranging from 800°C to 1000°C, was exce7Llent as no change was caused by 40 rubbing movements or moms against the specimens. This appears to result from the generation of necks between Ti02 particles on the surface in an initial sintering phase. When heated at 1100°C, the TiOz layer of the surface of a multi-functional material that wars cooled, solidified, and taken out of the roller-hearth kiln was cracked. Judging from TMA measure-ments of the TiO;, test piece, the crack is considered to be 21~5~22 caused by an intermediate sintering phase which brought about a prominent volume shrinkage of the Ti02 particles.
The antibacterial capability of the specimens Nos.
4 and 5 had a poor value of -. Two factors appear to be responsible for the poor antibacterial capability. One fac-tor is that the Ti02 particles went through a phase transi-tion to the ruti.le structure, and the other is that the sin-tering temperature was higher than the softening temperature of the binder by 300°C or more and the viscosity of the binder was so low that the Ti02 particles of the photocata-lytic layer were embedded in the binder layer. The fact that the Ti02 particles went through a phase transition to the rutile structure should not be considered to be the only cause of the poor antibacterial capability because the ru-tile Ti02 structure has a certain degree of photocatalytic activity though it is lower than the anatase TiOZ structure.
For Inventive Example, a specimen which was prepared by coating a Ti02 sol directly on a porous alumina base by spray coating, firing the assembly at 950°C, and then cooling and solidifying the assembly had an antibacterial capability of +. Therefore, the poor antibacterial capability of the specimens Nos. 4 and 5 was also caused by the fact that the sintering temperature was higher than the softening tempera-ture of the binder by 300°C or more and the viscosity of the binder was so low that the Ti02 particles of the photocata-lytic layer were: embedded in the binder layer.

.._ 215522 An analysis of the elements Ti and Si (which are primary components of the binder) by EBMA in the cross sec-tion of the specimens indicated that a layer composed of a mixture of Ti and Si was observed, confirming that photo-catalytic particles of Ti02 were embedded.
Above Inventive Example 1, i.e., the multi-functional material comprising a photocatalyst of Ti02 and a binder layer of Si02-A1203-Na/Rz0 frit, confirmed the follow-ing facts:
~O When a multi-functional material was manufac-tured under the condition of a firing temperature which was higher than the softening temperature of the binder by 20°C
or higher but not higher than 300°C, the multi-functional material had good antibacterial and wear-resistant capabili-ties. The reason for this appears to be that the viscosity of the binder was adjusted in the above temperature range to allow Ti02 particles to be adequately embedded in the binder layer.
O With the multi-functional material manufactured as described above in ~O, TiOz particles were confirmed as being embedded in the binder layer.
m When the firing temperature ranges from 800°C
to 1000°C, the wear resistance of any specimens was not changed and rem<<ined excellent even after 40 rubbing move-ments or more against the specimens. This appears to result from the strong bonding of Ti02 particles due to the genera-tion of necks bEaween the TiOZ particles.

__ 2I~~g22 (Inventive Example 2) After a binder layer composed of Si02-A1z03-Pb0 frit was formed ~on the surface of an alumina base (alumina purity: 96 %) having a size of 100 x 100 x 5 mm by spray coating and then dried, an aqueous solution of 15 % of Ti02 sol (which was the same as that in Inventive Example 1) was coated on the binder layer by spray coating, forming a TiOz layer having a thickness of 0.8 ~tm. Then, the bass with the binder layer and the TiOz layer formed thereon was heated at different atmospheric temperatures for respective specimens by a roller-hearth kiln, and thereafter cooled and solidi-fied into a multi-functional material.
ChangE~s in the antibacterial and wear-resistant capabilities of specimens of the multi-functional material whose base was alumina and binder was Si02-A1203-Pb0 frit as the firing temperature varied are given in Table 2 below.
(Table 2) Base =- alumina plate (100 x 100 x 5 mm), binder =
SiO,-A1,0,-Pb0 fr.it, photocatalyst = TiO, No. 6 7 8 9 10 Firing temperature (C) 560 580 740 840 860 Difference with softening 20 40 200 300 320 temperature (C

Antibacterial capability ++ +++ +++ ++ +

Wear resistance O O O O O

The S~LOZ-A1203-Pb0 frit used as the binder had a softening temperature of 540°C, a specific gravity of 3.8, ._ 2I~~~22 and a coated film thickness of 150 ~tm. The crystalline structure of Tii~2 of all the specimens was an anatase struc-ture.
In the wear resistance test shown in Table 2, the specimen No. 6 Haas damaged and the photocatalytic layer was peeled off by 10 rubbing movements or less against the specimen. The ;specimens Nos. 7 and 8 were not damaged by 10 rubbing movements or more against the specimens, and the specimens Nos. ~~ and 10 were not damaged by 40 rubbing move-ments or more against the specimens.
The specimens Nos. 9 and 10 were not damaged by 40 rubbing movements or more against the specimens because necks were developed between TiOz particles, firmly joining them, since the firing temperature was higher than 800°C.
The specimen No. 6 was damaged and the photocata-lytic layer was peeled off by 10 rubbing movements or less against the specimen because the firing temperature was only 20°C higher than the softening temperature of the binder, so that the viscosity of the binder was not made sufficiently low, and hence ithe anatase Ti02 particles which made up the lowermost layer of the photocatalytic layer were not suffi-ciently embedded in the binder layer.
The specimens Nos. 7 and 8 were not damaged by 10 rubbing movements or more against the specimens because though the firing temperature was not high enough to gener-ate necks, the difference between the firing temperature and the softening tE:mperature of the binder adjusted the viscos-ity of the binds~r to a value which allowed Ti02 particles to be adequately embedded in the binder layer.
In thE: antibacterial test shown in Table 2, each of the specimen's Nos. 6 - 9 had a good antibacterial value of +++ or ++, but the specimen No. 10 had an antibacterial value of +. This is because the sintering temperature was 320°C higher than the softening temperature of the binder and the ~iscosit:y of the binder was so low that the TiOz par-ticles of the photocatalytic layer were embedded in the binder layer.
( Inventive Exams>le 3 ) Si02-P.1203-Ba0 frit was melted, cooled, and then solidified in a mold, and shaped into a glass sheet having a size of 100 x 1C10 x 1 mm, and an aqueous solution of 15 % of TiOz sol (which was the same as that in Inventive Example 1) was coated on the glass sheet by spray coating, forming a TiOz layer having a thickness of 0.8 ~.un. Thereafter, the glass sheet was placed on an alumina base having a size of 100 x 100 x 5 mm, and heated and fired at different atmos-pheric temperatures for respective specimens by a siliconite furnace, after which it was cooled and solidified into a multi-functional. material.
Changes in the antibacterial and wear-resistant capabilities of specimens of the above multi-functional ma-terial as the f»ring temperature varied are given in Table 3 below.
(Table 3) zl5~~zz Base =~ alumina plate (100 x 100 x 5 mm), binder =
SiO,-A1,0,-Ba0 shEaet, photocatalyst = TiO
No. 11 12 13 14 Firing temperature (C) 640 740 840 940 Difference with softening 20 120 220 320 temperature ( C ) Antibacterial capability ++ +++ +++ -Wear resistance O O O O

The Si.02-A1203-Ba0 frit used as the binder had a softening temperature of 620°C, and a specific gravity of 2.8. The crystalline structure of TiOZ on the multi-functional material was an anatase structure for the speci-mens Nos. 11 - 13, and a rutile structure for the specimen No. 14.
In they wear resistance test shown in Table 3, the specimen No. 11 was damaged and the photocatalytic layer was peeled off by 10 rubbing movements or less against the specimen. The specimen No. 12 was not damaged by 10 rubbing movements or more against the specimen, and the specimens Nos. 13 and 14 were not damaged by 40 rubbing movements or more against the specimens.
The sF~ecimens Nos. 13 and 14 were not damaged by 40 rubbing movements or more against the specimens because necks were developed between Ti02 particles, firmly joining them, since the firing temperature was higher than 800°C.
The s~~ecimen No. 11 was damaged and the photocata-lytic layer was peeled off by 10 rubbing movements or less zm~s22 against the specimen because the firing temperature was only 20°C higher than the softening temperature of the binder, so that the viscosity of the binder was not made sufficiently low, and hence the anatase TiO~ particles which made up the lowermost layer of the photocatalytic layer were not suffi-ciently embedded in the binder layer.
The s~~ecimen No, 12 was not damaged by 10 rubbing movements or more against the specimens because though the firing temperature was not high enough to generate necks, the difference between the firing temperature and the sof-tening temperature of the binder adjusted the viscosity of the binder to a value which allowed TiOZ particles to be ade-quately embeddedl in the binder layer.
In them antibacterial test shown in Table 3, each of the specimen~o Nos. 11 - 13 had a good antibacterial value of +++ or ++, but the specimen No. 14 had an antibacterial value of -. This is because the TiOz particles are of a ru-tile structure and the sintering temperature was 320°C
higher than the softening temperature of the binder and the viscosity of ths: binder was so low that the Ti02 particles of the photocatalyt:ic layer were embedded in the binder layer.
As de;~cribed above, a process of producing a multi-functiona7_ material by coating TiOz particles on a binder, then applying them to a base, and firing the assem-bly, is as effective and advantageous as the process of pro-ducing a multi-i_unctional material by coating a binder on the surface of a base and then coating TiOz particles.

'~I5~~22 ( Inventive ExamF~le 4 ) After a binder of acrylic resin was coated on the surface of a bare of polyimide having a size of 100 x 100 x mm, an aqueous solution of 15 % of Ti02 sol was coated on the binder sprain coating, forming a Ti02 layer having a thickness of 0 . f3 ~tm. Thereafter, the base with the binder layer and the Ti02 layer formed thereon was fired at 150°C by a nichrome furnace, thereby manufacturing a multi-functional material.
Chang~as in the antibacterial and wear-resistant capabilities of specimens of the above multi-functional ma-terial as the firing temperature varied are given in Table 4 below.
(Table 4) Base ~= polyimide, binder = acrylic resin, photo-catalyst = Ti0" firing temperature: 150°C
No. 15 16 Antibacterial c<~pability - ++

Wear resistance O O

For the specimens in Table 4, the aqueous solution of 15 % of TiOz sol was adjusted as follows:
No. 15: The aqueous solution of 15 % of Ti02 sol which was the same as that in Inventive Example 1 was used.
No. 16: After an aqueous solution of TiCl was hy-drolyzed at 110 - 150°C in an autoclave, the product was adjusted to a ply of 0.8 by nitric acid, and dispersed with-out a surface modifier, after which agglomerates were re-._ 2155$22 moved. The aqueous solution was spray-coated immediately after agglomerates were removed.
The Ti.02 had a specific gravity of 3.9 and an ana-tase structure. The acrylic resin had a specific gravity of 0.9 and was rendered viscous at 70°C, which is equivalent to the softening temperature of glass.
With respect to the wear resistance, the specimens Nos. 15 and 16 were not damaged by 10 rubbing movements or more against the specimens under any conditions thereof.
This appears to result from the fact that the difference between the firing temperature and the softening temperature of the binder adjusted the viscosity of the binder to a value which allowed TiO~ particles to be adequately embedded in the binder layer.
In them antibacterial test, the specimen No. 15 an antibacterial value of -, but the specimen No. 16 had a good antibacterial value of ++. Therefore, it was found out that a multi-functional material can be manufactured which have an antibacterial capability even at temperatures lower than 30°C. The difference between the antibacterial capabilities of the specimens Nos. 15 and 16 is considered to depend on whether there is an organic component covering Ti02 or not because a component is decomposed and vaporized from the Ti02 sol of the specimen No. 15 at 200 - 350°C, but no such com-ponent is decom~bsed and vaporized from the Ti02 sol of the specimen No. 16 based on DTA-TG observations.

__ 2I55~22 The difference between the specific gravities of the anatase structure of Ti02 and the acrylic resin is 3. It was confirmed that with such a specific gravity difference, the Ti02 particlE~s making up the photocatalytic layer were not embedded in the binder layer and exhibited a good anti-bacterial capability.
(Inventive Example 5) After a binder layer composed of frit, which had different specific gravities for respective specimens, was formed on the surface of an alumina base having a size of 100 x 100 x 5 mm by spray coating and then dried, an aqueous solution of 15 ~ of TiOz sol was coated on the binder layer by spray coating, forming a Ti02 layer having a thickness of 0.8 Eun. Then, the base with the binder layer and the Ti02 layer formed thereon was heated and fired at an atmospheric temperature of 750°C by a roller-hearth kiln, and thereafter cooled and solidified into a multi-functional material.
ChangE~s in the antibacterial and wear-resistant capabilities of specimens of the above multi-functional ma-terial as the firing temperature varied are given in Table 5 below.
(Table 5) Base =~ alumina plate (100 x 100 x 5 mm), photo-catalyst = TiO
No. 17 18 19 20 Type of binder Si02-A1203- SiO2-AlzO3-Pb0 Pb0 zl~~szz Specific graviton of binder 5.3 3.8 2.8 2.4 Specific gravit~r of TiOz 3.9 3.9 3.9 3.9 Softening temperature (C) 480 540 620 680 of frit Firing temperature (C) 750 750 750 750 Antibacterial c<~pability ++ +++ +++ +++

Wear resistance x O O O

In the antibacterial test, each of the specimens Nos. 17 -- 20 had a good antibacterial value of +++. This is considered to result from the fact that the firing tempera-tune of each of the specimens Nos. 17 - 20 was higher than the softening temperature of the binder by 30°C or more or 300°C or less, and the difference between the firing tem-perature and the softening temperature of the binder ad-justed the viscosity of the binder to a value which allowed Ti02 particles t;o be adequately embedded in the binder layer.
With respect to the wear resistance, the photo-catalytic layer of the specimen No. 17 was damaged and peeled off by 5 rubbing movements or less against the speci-men, but the sp~scimens Nos. 18 -- 20 were not damaged by 10 rubbing movements or more against the specimens.
The reason for this appears to be that unlike the other specimens, the specific gravity of the binder of the specimen No. 17 was greater than that of Ti02, and as a re-sult, the anatase TiOz particles making up the lowermost layer of the ph~otocatalytic layer were not sufficiently em-bedded in the binder layer.

_~_ 215522 Therei:ore, it was found out that the wear resis-tance of the mufti-functional material is affected by the specific graviti.es of the Ti02 and the binder layer, and is lowered if the specific gravity of the binder is greater than the specific gravity of the Ti02.
(Inventive Example 6) After a binder layer composed of Si02-A1203-Ba0 frit (softening temperature: 620°C) was formed on the sur-face of a base i.n the form of a square pottery tile with each side 150 mm long, an aqueous solution composed of a stirred mixture of a TiOz sol and an SnOz sol was coated on the binder layer by spray coating. Thereafter, the assembly was fired at 750°C and cooled and solidified into a multi-functional material.
The concentration of the Ti02 sol was in the range of from 4 to 6 Grt%, and the Ti02 sol was adjusted to a pH of 11 by an aqueou:o solution of NH3. The crystal diameter of the Ti02 particles was 0.01 dun, and the crystal diameter of the SnOz particles was 0.0035 dun.
The results of antibacterial and wear-resistant capability test:; which were conducted on the multi-functional material as the amount of Sn02 (molar ratio) with respect to the i:otal amount of Ti02 and Sn02 varied are given in Table 6 below.
(Table 6) _, 21~~~~2 Base = pottery tile, binder = Si02-A1203-Ba0 frit, photocatalyst = 'ri02, Interstitial particles = Sn02 (0.0035 t.~.m ) No. 21 22 23 24 25 Amount of Sn02 (mol %) 0 10 20 60 100 Antibacterial capability +++ +++ +++ ++ -Wear resistance O O O O O

The wear resistance increased as the amount of Sn02 increased. When 10 % or more of Sn02 was added, the specimens were not damaged and changed by 40 rubbing move-ments or more against the specimens.
When the added amount of Sn02 was up to 20 %, the antibacterial value was +++ as was the case with no SnOZ
added. When the added amount of Sn02 was 60 %, the antibac-terial value was ++. When more Sn02 was added, the probabil-ity that Sn02 covered the Ti02 particles on the surface of the base increased, resulting in a reduction in the antibac-terial capability. When the added amount of Sn02 was 100 %, the antibacterial value was -.
Therefore, the multi-functional material can have excellent antibacterial and wear-resistant capabilities if the added amount of SnOz in terms of a molar ratio was 10 %
or more or 60 % or less, preferably, 10 % or more or 20 % or less of the total amount of TiOz and Sn02.
As them amount of Sn02 increases, the wear resis-tance of the multi-functional material increases by the mechanism described below. Since Sn02 has a vapor pressure _ 21~~~?2 higher than that of TiOz at temperatures higher than 600°C, the distance between two TiOz particles is Lo before sinter-ing as shown in FIG. 17(a). The vapor pressure is higher at the surfaces of the TiOz particles which have a positive cur-vature, and lower at surfaces having a negative curvature, i.e., the surface of a neck where two TiOz particles abut against each other. As a result, as shown in FIG. 17(b), SnOZ having a va~~or pressure Y.igher than that of Ti02 enters the neck, and is condensed as shown in FIG. 17(c). The as-sembly is thus sintered by a vaporization - condensation mechanism.
When t:he assembly is sintered by a vaporization -condensation mechanism, the distance LZ between the Ti02 par-ticles after being sintered is substantially the same as the distance Lo before sintering, and hence no crack is devel-oped.
As de:scribed above, if a composite material in-cluding a TiOz particle layer retained on the surface of a base by a binder with Sn02 particles filling interstices be-tween TiOz particles exposed on the outermost surface is pro-duced by being fared at a temperature of 600°C or higher, then the composite material has increased wear resistance as necks between th.e TiOz particles are joined without develop-ing cracks.
(Comparative Example 7) As wii:h Inventive Example 6, a binder layer com-posed of Si02-A1.,03-Ba0 frit ( softening temperature : 620°C ) 2I55~22 was formed on the surface of a base in the form of a square pottery tile with each side 150 mm long, and then an aqueous solution composed of a stirred mixture of a TiOZ sol and an Sn02 sol was coat=ed on the binder layer by spray coating.
Thereafter, the assembly was fired at 750°C and cooled and solidified into a multi-functional material.
The cc>ncentration of the Ti02 sol was in the range of from 4 to 6 wt%, and the TiOZ sol was adjusted to a pH of 11 by an aqueous solution of NH3. The crystal diameter of the Ti02 particles was 0.01 N.m as with Inventive Exaunple 6, but the crystal diameter of the Sn02 particles was 0.008 ~.im, slightly greater than that in Inventive Example 6.
The rsasults of antibacterial and wear-resistant capability tests which were conducted on the multi-functional material thus produced are given in Table 7 be-low.
(Table 7) Base =- pottery tile, binder = Si02-A1203-Ba0 frit, photocatalyst = Ti02, Interstitial particles = SnOz (0.0080 u.m) , Heated at 750°C
No. 26 27 28 29 30 Amount of Sn02 (~mol % ) 0 10 20 60 100 Antibacterial capability +++ +++ +++ ++ -Wear resistance O O O O O

The e~Efect which the Sn02 particles having a di-ameter of 0.008 ~,~m had on the wear resistance was smaller than the SnOz particles having a diameter of 0.0035 ~tm. When 60 % or more (molar ratio) of Sn02 with respect to the total of Ti02 and SnOZ was added, the specimens were not damaged and changed by 9~0 rubbing movements or more against the specimens.
With respect to the antibacterial capability, when the added amount: of Sn02 was up to 20 %, the antibacterial value was +++ a~~ was the case with no Sn02 added. When the added amount of Sn02 was 60 %, the antibacterial value was ++. When more ~~n02 was added, the probability that Sn02 cov-eyed the Ti02 particles on the surface of the base increased, resulting in a reduction in the antibacterial capability.
When the added amount of Sn02 was 100 %, the antibacterial value was -.
There~Eore, when Ti02 particles having a diameter of 0.01 ~tm are employed, it is difficult to produce a multi-functional material which is excellent in both antibacterial and wear-resistant capabilities by adding Sn02 particles hav-ing a diameter of 0.0035 ~tm. The reason for this appears to be that the vapor pressure of SnOz particles decreases as the particle diameter increases, and whereas Sn02 particles hav-ing a diameter of 0.0035 ~.tm that remain unvaporized exist in the interstices between Ti02 particles and are effective in increasing the Bonding strength, Sn02 particles having a di-ameter of 0.008 dun do not enter the interstices between Ti02 particles, but a.re highly probably present on the TiOz parti-cles because the Sn02 particles are greater than the inter-stices between Ti02 particles.

r_ 2I5a822 Conse~~uently, the size of Sn02 particles to fill the interstices between Ti02 particles should preferably 4/5 or less of the size of the Ti02 particles.
(Inventive Example 8) A binder layer composed of SiOz-A1203-Ba0 frit (softening temperature: 620°C) was formed on the surface of a base in the form of a square pottery tile with each side 150 mm long, and then an aqueous solution of Ti02 sol was coated on the b_Lnder layer by spray coating. Thereafter, the assembly wa:a fired at 750°C and cooled and solidified into a compositca material. An aqueous solution of SnOz sol was coated on the composite material, and the assembly was then heated at :110°C, thereby producing a multi-functional material. The aqueous solution of TiOZ sol was the same as that used in Inventive Example 6, and the aqueous solution of Sn02 sol contained SnOZ particles having a diameter of 0.0035 Ltm.
The results of antibacterial and wear-resistant capability test:~ which were conducted on the multi-functional material thus produced are given in Table 8 be-low.
(Table 8) Base = pottery tile, binder = Si02-A1Z03-Ba0 frit, photocatalyst = Ti02, Interstitial particles = Sn02 (0.0035 u.m) , Heated at 750°C/110°C
No. 31 32 33 34 35 Amount of Sn02 (mol ~) 0 10 20 60 100 _ zl~~szz Antibacterial capability +++ +++ +++ ++ -Wear resistance O O O O O

The wear resistance increased as the added amount of Sn02 increased. When 20 % or more (molar ratio) of SnOz was added, the specimens were not damaged and changed by 40 rubbing movement, or more against the specimens.
With respect to the antibacterial capability, when the added amount: of SnOZ was up to 20 %, the antibacterial value was +++ as was the case with no Sn02 added. When the added amount of Sn02 was 60 %, the antibacterial value was ++. When more Sn02 was added, the probability that SnOz cov-Bred the TiOz particles on the surface of the base increased, resulting in a reduction in the antibacterial capability.
When the added amount of SnOz was 100 %, the antibacterial value was -.
Since the Sn02 sol was heated at a low temperature of 110°C, the a:;sembly was not sintered according to the vaporization - ~~ondensation mechanism described above in Inventive Examp:Le 6. Nevertheless, the wear resistance in-creased because the bonding between Ti02 particles was strengthened by Sn02 particles, which had a diameter smaller than the Ti02 p2~rticles, i.e., had a greater specific surface area and a higher adsorbing power, filled the interstices between the TiO., particles.
(Inventive Exam~~le 9) A binder layer composed of Si02-Alz~3-Ba0 frit (softening temperature: 620°C) was formed on the surface of ~_ 2155822 a base in the form of a square pottery tile with each side 150 mm long, and then an aqueous solution of Ti02 sol was coated on the binder layer by spray coating. Thereafter, the assembly was fired at 750°C and cooled and solidified into a composite material. An aqueous solution of copper acetate was coated on the composite material and then dried, after which the assembly was irradiated with light contain-ing ultraviolet rays to fix copper ions to a photocatalytic layer while reducing the copper ions, thereby producing a multi-functional material. The assembly was irradiated with light by a mercury lamp.
The :size of the particles of Cu fixed to the pho-tocatalytic layer was about 0.004 dun on the average.
The results of antibacterial and wear-resistant capability tests which were conducted on the multi-functional material thus produced are given in Table 9 be-low.
(Table 9) Base = pottery tile, binder = SiOz-A1z03-Ba0 frit, photocatalyst = TiOz, Interstitial particles = Cu (0.004 ~tm), Heated at 750°C/photoreduced No. 36 37 38 39 40 Amount of Cu (n~ol % ) 0 10 20 60 100 Antibacterial capability +++ +++ +++ +++ +++

Wear resistance: O O O O O

The wear resistance increased as the added amount of Cu increased.. When 20 % or more (molar ratio) of Cu was zm~~2z added, the specimens were not damaged and changed by 40 rub-bing movements ~~r more against the specimens.
With respect to the antibacterial capability, when the added amount of Cu was up to 20 %, the antibacterial value was +++ as was the case with no Cu added. Since Cu has an antibacterial capability itself, no reduction in the antibacterial capability was appreciated when Cu was added in a large amount.
However, it can be considered that if the added amount of Cu is small, then the photocatalytic action of the TiOz particle layer is prevalent, and if the added amount of Cu is large, then the action of Cu is prevalent. If only the action of Cu is relied upon, then its service life ap-pears to be shorter than if no photocatalyst were present because Cu is gradually eluted when used in a liquid. Since Cu added in a large amount results in an increased cost, it appears meaningless to unduly increase the added amount of Cu.
Inventive Example 9 confirmed that not only parti-cles of an oxide such as SnOz, but also particles of a metal such as Cu can be used as particles to fill the interstices in the Ti02 pariticle layer.
(Inventive Example 10) A binder layer composed of Si02-A1203-Ba0 frit (softening temperature: 620°C) was formed on the surface of a base in the form of a square pottery tile with each side 150 mm long, anal then an aqueous solution of TiOz sol was ~_ 2155822 coated on the binder layer by spray coating. Thereafter, the assembly was fired at 950°C and cooled and solidified into a composite material. An aqueous solution of copper acetate was coatE~d on the composite material, after which the assembly was irradiated with light containing ultravio-let rays to fix copper ions to a photocatalytic layer while reducing the copper ions, thereby producing a multi-functional material.
The assembly was irradiated with light for several minutes by a BLB lamp. The Ti02 structure underwent a phase transition from ~~n anatase structure to a rutile structure in the heat treatment. The film thickness of Ti02 was ad-justed to 0.4 Etm upon spray coating.
Antibacterial and wear-resistant capability tests were conducted o:n the multi-functional material thus manu-factured. The wear resistance of the multi-functional mate-rial was good in the temperature range even if no Cu was added. When Cu 'was added, the specimens were not damaged and changed by 40 rubbing movements or more against the specimens as was the case with no Cu added.
The results of the antibacterial test are shown in FIG. 18. When n~o Cu was added, the antibacterial capability had a poor value of + because the TiOZ was of the rutile structure. As Cu was added, the antibacterial capability increased. Irrespective of whether irradiated with the BLB
lamp or not, the antibacterial activity had a value of ++ if the carried amount of Cu was 0.7 ~,g/cmz or greater, and a value of +++ if the carried amount of Cu was 1.2 pg/cm2 or greater.
It can be seen from the foregoing that for produc-ing a multi-funcaional material which is excellent in both antibacterial and wear-resistant capabilities, the carried amount of Cu should be 0.7 pg/cm2 or greater, and more pref-erably 1.2 p.g/cnn2 or greater.
The carried amount of Cu is greatly increased if a drying step is included after the aqueous solution of copper acetate is coated and before the assembly is irradiated with the BLB lamp. ~~he relationship is shown in FIG. 19. This is because the concentration of metal ions when they are photoreduced is made higher by being dried.
The carried amount of Cu is maximized when the coated amount o:E Cu is optimized, as shown in FIG. 20 which illustrates the use of copper acetate containing 1 wt % of Cu. In order to make the coated amount of Cu equal to 0.7 p.g/cmz or greats:r in FIG. 20, the carried amount of Cu may be equal to or greater than 0.2 mg/cm2 or equal to or smaller than 2.7 mg/cm2. In order to make the coated amount of Cu equal to 1.2 ~,g/cm2 or greater in FIG. 20, the carried amount of Cu may be equal to or greater than 0.3 mg/cmz or equal to or smaller than 2.4 mg/cm2.
(Inventive Example 11) A binder layer composed of SiOZ-A1203-Ba0 frit (softening temperature: 680°C) was formed on the surface of a base in the form of a square pottery tile with each side __ 215522 150 mm long, and. then an aqueous solution of Ti02 sol was coated on the binder layer by spray coating. Thereafter, the assembly was. fired at 950°C and cooled and solidified into a composite material. An aqueous solution of silver nitrate was coated on the composite material and dried, af-ter which the assembly was irradiated with light containing ultraviolet rays to fix silver ions to a photocatalytic layer while reducing the silver ions, thereby producing a multi-functional material.
The assembly was irradiated with light for several minutes by a BLH lamp. The Ti02 structure underwent a phase transition from an anatase structure to a rutile structure in the heat treatment. The film thickness of Ti02 was ad-justed to 0.4 ~t~m~ upon spray coating.
Antibacterial and wear-resistant capability tests were conducted c~n the multi-functional material thus manu-factured. The wear resistance of the multi-functional mate-rial was good in the temperature range even if no Cu was added. When Ag was added, the specimens were not damaged and changed by 40 rubbing movements or more against the specimens as was the case with no Ag added.
The rEasults of the antibacterial test are shown in FIG. 70. When no Ag was added, the antibacterial capability had a poor value of + because the Ti02 was of the rutile structure. As A.g was added, the antibacterial capability increased. Irrespective of whether irradiated with the BLB
lamp or not, the antibacterial activity had a value of ++ if _.. 2I~5~22 the carried amount of Ag was 0.05 ~,g/cm2 or greater, and a value of +++ if the carried amount of Ag was 0.1 ~,g/cm2 or greater.
For producing a multi-functional material which is excellent in both antibacterial and wear-resistant capabili-ties, therefore, the carried amount of Ag should be 0.05 ~.g/cm2 or greater, and more preferably 0.1 ~g/cm2 or greater.
If ths: carried amount of Ag is large, the multi-functional material is colored with brown or black, result-ing in an unsightly appearance. However, the multi-functional material is not colored if the carried amount of Ag is 1 ~.g/cm2 or smaller.
It can be understood from the foregoing that the carried amount of Ag should be equal to or greater than 0.05 ~,g/cm2 or equal 1~0 or smaller than 1 ~,g/cm2, and more pref-erably equal to or greater than 0.1 ~g/cm2 or equal to and smaller than 1 ~g/cmz.
(Inventive Example 12) A binder layer composed of SiOz-A1203-Ba0 frit (softening temperature: 680°C) was formed on the surface of a base in the form of a square pottery tile with each side 150 mm long, and then an aqueous solution of Ti02 sol was coated on the binder layer by spray coating. Thereafter, the assembly was fired at 950°C and cooled and solidified into a composite material. An aqueous solution of silver nitrate was coated on the composite material and dried, af-ter which the assembly was irradiated with light containing z155~zz ultraviolet rays to fix silver ions to a photocatalytic layer while reducing the silver ions, thereby producing a multi-functional material.
The assembly was irradiated with light for several minutes by a BLB lamp. The Ti02 structure underwent a phase transition from an anatase structure to a rutile structure in the heat treatment.
Antibacterial and wear-resistant capability tests were conducted on the multi-functional material thus manu-factured while changing the film thickness of TiOz to various values.
The ws~ar resistance of the multi-functional mate-rial was good in the TiOz film thickness range of 2 ~tm or below which was tested. No specimens were damaged and changed by 40 rubbing movements or more against the speci-mens.
The antibacterial capability had a value of ++
when the film thickness was 0.1 ~tm or more, and a value of +++ when the film thickness was 0.2 N,m or more. Therefore, the film thickness of Ti02 should be 0.1 dun or more, and more preferably be 0.2 ~tm or more.
(Inventive Example 13) A binder layer composed of SiOZ-A1Z03-Ba0 frit (softening temperature: 620°C) was formed on the surface of a base in the form of a square pottery tile with each side 150 mm long, and then an aqueous solution of zinc chloride or Ti02 sol was coated on the binder layer by spray coating 2~~5~~2 and dried. Thereafter, an aqueous solution of silver ni-trate was coated on the assembly, and then irradiated with light containing ultraviolet rays to fix silver ions to a photocatalytic :Layer while reducing the silver ions. There-after, the assembly was fired at a temperature in the range of from 900°C to 1000°C, and cooled and solidified into a multi-functiona:L material.
The assembly was irradiated with light for severn~
minutes by a BL~3 lamp. The Ti02 structure under'vent a phase transition from an anatase structure to a rutile structure in the heat treatment. Inasmuch as the fixed Ag on the sur-face changed from brownish black to white in the heat treat-ment, the Ag was considered to change into silver oxide dur-ing firing. Ho~iever, inasmuch as the Ag was attached and fixed discretel~~, substantially no growth of Ag particles was observed before and after the firing step.
Antibacterial and wear-resistant capability tests were conducted o~n the multi-functional material thus manu-factured. The wear resistance of the multi-functional mate-rial was good in the temperature range even if no Ag was added. When Cu was added, the specimens were not damaged and changed by 40 rubbing movements or more against the specimens as was the case with no Ag added.
The results of the antibacterial test are shown in FIG. 70. When no Ag was added, the antibacterial capability had a poor value of + because the Ti02 was of the rutile __ 2155822 structure. As ~~g was added, the antibacterial capability increased.
(Inventive Example 14) A binder layer composed of Si02-A1203-Ba0 frit (softening tempE~rature: 620°C) was formed on the surface of a base in the form of a square pottery tile with each side 150 mm long, and then the assembly was fired at a tempera-ture in the rankle of from 900°C to 1000°C, and cooled and solidified into a compound material. An aqueous solution of silver nitrate was coated on the composite material, and thereafter irradiated with light containing ultraviolet rays to fix silver ions to a photocatalytic layer while reducing the silver ions.. An aqueous solution of 0.1 mol/1 of RI was coated on the surface of the composite material at a rate of 0.1 cc/cm2, and then irradiated with light containing ultra-violet rays for 5 seconds, thereby producing a multi-functional material. At this time, the carried amount of Ag was 2 Eun/cm2.
Since the aqueous solution of 0.1 mol/1 of RI was coated on the surface of the composite material at a rate of 0.1 cc/cmz, and then irradiated with light containing ultra-violet rays for 5 seconds, the multi-functional material which was brownish black was discolored into white, and hence had an improved appearance.
(Inventive Example 15) A binder layer composed of Si02-A1203-Ba0 frit (softening tempE:rature: 620°C) was formed on the surface of 2155g?2 a base in the form of a square pottery tile with each side 150 mm long, and then an aqueous solution of Ti02 sol was coated on the binder layer by spray coating. Thereafter, the assembly was fired at 820°C, and cooled and solidified into a multi-functional material. The multi-functional ma-terial was obliquely placed, and irradiated with light con-taining ultraviolet rays. During this time, bathtub water collected in a pubic bath was continuously dropped onto the multi-functional material while the bathtub water was being circulated, and the bathtub water was observed for changes.
For comparison, bathtub water was also dropped onto a base free of a photocatalytic layer. Observations after 14 days indicated that no special difference as to turbidity was appreciated, but a difference as to sewage-like odor was appreciated, between the bathtub water dropped onto the multi-functional material and the bathtub water dropped onto the base free of a photocatalytic layer. Specifically, a considerably strong sewage-like odor was appreciated from the bathtub water dropped onto the base free of a photocata-lytic layer, and slime and organic deposits were observed on the base free of a photocatalytic layer. However, neither sewage-like odor nor slime and organic deposits were appre-ciated from the bathtub water dropped onto the multi-functional material and on the multi-functional material.
It can be seen from the above simulating experiments that the multi-functional material can be used as the material of zm~~22 artificial stones for use with circulating-water falls and fountains in parks, department stores, and other facilities.
As described above, photocatalytic particles are fixed to a base through a binder layer made of a material having a softening temperature lower than that of the base, and photocatalytic particles making up a surface layer of a photocatalytic layer are not embedded in the binder layer.
Therefore, the photocatalytic particles of the surface layer have surfaces exposed for sufficiently performing their pho-tocatalytic effect. Those photocatalytic particles which make up a lower layer of the photocatalytic layer are partly embedded in the binder layer, so that the photocatalytic layer is retained under increased retentive forces against peel-off.
FIG. 21 is illustrative of a method of manufactur-ing a multi-functional material having photocatalytic func-tions according to another embodiment of the present inven-tion. According to this embodiment, a base 1 of a thermo-plastic material such as inorganic glass, thermoplastic resin, or the like is used, and a photocatalytic layer 2 is formed directly on the surface of the thermoplastic base 1.
Specifically, as shown in FIG. 21(a), a thermo-plastic base 1 is prepared, and then, as shown in FIG.
21(b), a photocatalytic layer 2 composed of photocatalytic particles such as TiOz particles or the like is formed on the surface of the thermoplastic base 1. Thereafter, the assem-bly is heated to allow a lower layer of the photocatalytic 2I5~8?~
layer 2, closer to the thermoplastic base 1, to be settled into the thermoplastic base 1 and embedded therein, as shown in FIG. 21(c), whereupon the lower layer of the photocata-lytic layer 2 is firmly retained in place. Photocatalytic particles 3 of the photocatalytic layer 2, which make up a surface layer that contacts the atmosphere, are joined to-gether by a potential energy, intermolecular forces, or sin-tering.
Preferred conditions relative to this embodiment are the same as those of the preceding embodiment. Specific Inventive Examples will be described below.
(Inventive Example 16) An aqueous solution of 15 % of Ti02 sol was coated on the surface of a square glass base of Si02-A1203-Na/KZO
with each side 150 mm long by spray coating, forming a TiOZ
layer having a thickness of 0.8 ~tm. Then, the glass base with the Ti02 layer formed thereon was placed in a ceramic mold with good mold releasability, and heated at different atmospheric temperatures for respective specimens by a roller-hearth kiln, and thereafter cooled and solidified into a multi-functional material.
The aqueous solution of 15 % of Ti02 sol was pro-duced by hydrolyzing TiCld, for Inventive Example, in an autoclave under a hydrothermal condition ranging from 100 to 200°C to produce anatase Ti02 having a crystal diameter rang-ing from 0.007 to 0.2 dun, and dispersing several to several tens % of the anatase TiOz in a sol state in an acid aqueous 2155~?2 solution such as of nitric acid, hydrochloric acid or the like, or a basic aqueous solution such as of ammonia or the like. To increase the dispersibility of the anatase Ti02, there was added 0.5 ~ or less of a surface treating agent of an organic acid salt such as triethanolamine or trimethylo-lamine, pentaerythritol, trimethylolpropane, or the like.
The particle diameters of the TiOZ sol were calculated based on image processing on SEM observations, and the crystal diameter was calculated from the integration width of powder X-ray diffraction.
While the spray coating was employed to coat the aqueous solution, it may be coated by dip coating or spin coating.
The produced multi-functional material was evalu-ated for antibacterial and wear-resistant capabilities.
With respect to the antibacterial capability, the multi-functional material was tested for its antibacterial ability against escherichia coli, strain: W3110. Specifi-cally, 0.15 ml (1 -- 5 x 10' CFU) of the bacterial solution was dropped onto the outermost surface of the multi-functional material which had been sterilized with 70 ~
ethanol, and a glass sheet (10 x 10 cm) was placed in inti-mate contact with the outermost surface of the base, thus preparing a specimen. After the specimen was irradiated with light from a white-light lamp with 3500 luxes for 30 minutes, the bacterial solution on the irradiated specimen and the bacterial solution on a specimen kept under a _ 77 _ 21~5~22 shielded condition were wiped with a sterile gauze, and col-lected in 10 ml of physiological saline. The survival rates of the bacteria were determined as indications for evalua-tion.
The multi-functional material was tested for its wear resistance by rubbing it with a plastic eraser, and any change in the appearance thereof was compared and evaluated.
Changes in the antibacterial and wear-resistant capabilities of specimens of the multi-functional material whose glass base was composed of Si02-A1203-Na/Rz0 as the fir-ing temperature varied are given in Table 10 below.
(Table 10) Base = glass of Si02-A1Z03-Na/RzO, photocatalyst =
TiO, No. 1 2 3 4 5 Firing temperature (C) 700 780 880 980 1000 Difference with softening 20 100 200 300 320 temperature (C ) Antibacterial capability ++ +++ +++ - -Wear resistance D O O O O

+++: Survival rate of escherichia coli: less than 10 %
++ : Survival rate of escherichia coli: 10 % or more and less than 30 %
+ . Survival rate of escherichia coli: 30 % or more and less than 70 %
- . Survival rate of escherichia coli: 70 % or more O : Not varied after 40 reciprocating rubbing movements _ 78 _ against the specimens.
O . Damage was caused and the photocatalytic layer (Ti02 layer) was peeled off by 10 - 40 rubbing movements against the specimens.
O : Damage was caused and the photocatalytic layer (Ti02 layer) was peeled off by 5 - 10 rubbing movements against the specimens.
x . Damage was caused and the photocatalytic layer (T'~2 layer) was peeled off by 5 rubbing movements or less against the specimens.
The glass base of SiOZ-A1203-Na/K20 had a specific gravity of 2.4 and a softening temperature of 680°C. The Ti02 in Table 10 had an anatase structure and a specific gravity of 3.9 for the specimens Nos. 1 - 3, and a rutile structure and a specific gravity of 4.2 for the specimens Nos. 4 and 5.
In Table 10, since the firing temperature of the specimen No. 1 was only 20°C higher than the softening tem-perature of the glass base, so that the viscosity of the glass base was not made sufficiently low, the anatase Ti02 particles which made up the lowermost layer of the photo-catalytic layer were not sufficiently embedded in the glass base. As a result, the photocatalytic layer was damaged and peeled off by 5 -- 10 rubbing movements against the specimens in the wear resistance test. With respect to the antibacte-rial capability, since the photocatalytic layer was made of anatase Ti02 which is of good photocatalytic activity and the _ 79 _ organic component of the Ti02 sol was decomposed and vapor-ized based on TG-DTA observations at a temperature of 300°C
or higher, the dispersant such as a surface-treating agent or the like attached to the surface of the Ti02 layer was considered to be vaporized. As the firing temperature was 700°C much higher than the vaporizing temperature, the anti-bacterial capability had an excellent value of ++.
The durability of each cf the specimens Nos. 3 --5, which had a firing temperature ranging from 800°C to 1000°C, was excellent as no change was caused by 40 rubbing movements or more against the specimens. This appears to result from the generation of necks between TiOz particles on the surface in an initial sintering phase. When heated at 1100°C, the Ti02 layer of the surface of a multi-functional material that was cooled, solidified, and taken out of the roller-hearth kiln was cracked. Judging from TMA measure-ments of the Ti02 test piece, the crack is considered to be caused by an intermediate sintering phase which brought about a prominent volume shrinkage of the Ti02 particles.
The antibacterial capability of the specimens Nos.
4 and 5 had a poor value of -. Two factors appear to be responsible for the poor antibacterial capability. One fac-tor is that the Ti02 particles went through a phase transi-tion to the rutile structure, and the other is that the sin-tering temperature was higher than the softening temperature of the glass base by 300°C or more and the viscosity of the glass base was so low that the Ti02 particles of the photo-215~~22 catalytic layer were embedded in the glass base layer. The fact that the TiOz particles went through a phase transition to the rutile structure should not be considered to be the only cause of the poor antibacterial capability because the rutile Ti02 structure has a certain degree of photocatalytic activity though it is lower than the anatase TiOz structure.
For Inventive Example, a specimen which was prepared by coating a Ti02 sol directly on a porous alumin~ base by spray coating, firing the assembly at 950°C, and then cooling and solidifying the assembly had an antibacterial capability of +. Therefore, the poor antibacterial capability of the specimens Nos. 4 and 5 was also caused by the fact that the sintering temperature was higher than the softening tempera-ture of the glass base by 300°C or more and the viscosity of the glass base was so low that the TiOz particles of the pho-tocatalytic layer were embedded in the glass base layer.
An analysis of the elements Ti and Si (which are primary components of the glass base) by EBMA in the cross section of the specimens indicated that a layer composed of a mixture of Ti and Si was observed, confirming that photo-catalytic particles of Ti02 were embedded.
Above Inventive Example 16, i.e., the multi-functional material comprising a photocatalyst of Ti02 and a glass base of SiOz-A1z03-Na/R20, confirmed the following facts:
~O When a multi-functional material was manufac-tured under the condition of a firing temperature which was higher than the softening temperature of the glass base by 20°C or higher but not higher than 300°C, the multi-functional material had good antibacterial and wear-resistant capabilities. The reason for this appears to be that the viscosity of the glass base was adjusted in the above temperature range to allow Ti02 particles to be ade-quately embedded in the glass base layer.
D With the multi-functional material manufactured as described above in ~O, Ti02 particles were confirmed as being embedded in the glass base.
m When the firing temperature ranges from 800°C
to 1000°C, the wear resistance of any specimens was not changed and remained excellent even after 40 rubbing move-ments or more against the specimens. This appears to result from the strong bonding of Ti02 particles due to the genera-tion of necks between the TiOZ particles.
(Inventive Example 17) An aqueous solution of 15 % of TiOz sol (which was the same as that in Inventive Example 16) was coated on a glass base composed of Si02-A1203-Pb0 and having a size of 100 x 100 x 5 mm by spray coating, forming a Ti02 layer having a thickness of 0.8 ~.un. Then, the glass base with the TiOz layer formed thereon was placed in a ceramic mold with good mold releasability, and heated at different atmospheric tem-peratures for respective specimens by a roller-hearth kiln, and thereafter cooled and solidified into a multi-functional material.

_ 215522 Changes in the antibacterial and wear-resistant capabilities of specimens of the multi-functional material whose glass base was composed of Si02-A1203-Pb0 as the firing temperature varied are given in Table 11 below.
(Table 11) Base = Si.O.,-A1.,0.,-Pb0 Glass . nhc~tnra+-a 1.~a+ - m; n __ No. 6 7 8 9 10 Firir3 temperature (C) 560 580 740 840 860 Difference with softening 20 40 200 300 320 temperature ( C ) Antibacterial capability ++ +++ +++ ++ +

wear resistance D O O O O

The glass base of Si02-A1203-Pb0 had a softening temperature of 540°C and a specific gravity of 3.8. The crystalline structure of TiOz of all the specimens was an anatase structure.
In the wear resistance test shown in Table 11, the specimen No. 6 was damaged and the photocatalytic layer was peeled off by 10 rubbing movements or less against the specimen. The specimens Nos. 7 and 8 were not damaged by 10 rubbing movements or more against the specimens, and the specimens Nos. 9 and 10 were not damaged by 40 rubbing move-ments or more against the specimens.
The specimens Nos. 9 and 10 were not damaged by 40 rubbing movements or more against the specimens because necks were developed between Ti02 particles, firmly joining them, since the firing temperature was higher than 800°C.

21~~~22 The specimen No. 6 was damaged and the photocata-lytic layer was peeled off by 10 rubbing movements or less against the specimen because the firing temperature was only 20°C higher than the softening temperature of the glass base, so that the viscosity of the glass base was not made sufficiently low, and hence the anatase Ti02 particles which made up the lowermost layer of the photocatalytic layer were not sufficiently embedded in the glass base.
The specimens Nos. 7 and 8 were not damaged by 10 rubbing movements or more against the specimens because though the firing temperature was not high enough to gener-ate necks, the difference between the firing temperature and the softening temperature of the glass base adjusted the viscosity of the glass base to a value which allowed Ti02 particles to be adequately embedded in the glass base.
In the antibacterial test shown in Table 11, each of the specimens Nos. 6 -- 9 had a good antibacterial value of +++ or ++, but the specimen No. 10 had an antibacterial value of +. This is because the sintering temperature was 320°C higher than the softening temperature of the glass base and the viscosity of the glass base was so low that the Ti02 particles of the photocatalytic layer were embedded in the glass base.
(Inventive Example 18) An aqueous solution of 15 % of Ti02 sol (which was the same as that in Inventive Example 16) was coated on a glass base composed of SiOx-A1203-Ba0 and having a size of 100 ._ 2155822 x 100 x 5 mm by spray coating, forming a Ti02 layer having a thickness of 0.8 ~.un. Then, the glass base with the TiOz layer formed thereon was placed in a ceramic mold with good mold releasability, and heated at different atmospheric tem-peratures for respective specimens by a siliconite kiln, and thereafter cooled and solidified into a multi-functional material.
Changes in the antibacterial and wear-resistant capabilities of specimens of the above multi-functional ma-terial as the firing temperature varied are given in Table 12 below.
(Table 12) Base = Si02-A1203-Ba 0 glass, photocatalyst Ti02 =

No. 11 12 13 14 Firing temperature (C) 640 740 840 940 Difference with softening 20 120 220 320 temperature (C ) Antibacterial capability ++ +++ +++ -wear resistance D O O O

The glass base of SiOz-A1203-Ba0 had a softening temperature of 620°C and a specific gravity of 2.8. The crystalline structure of TiOz on the multi-functional mate-rial was an anatase structure for the specimens Nos. 11 --13, and a rutile structure for the specimen No. 14.
In the wear resistance test shown in Table 12, the specimen No. 11 was damaged and the photocatalytic layer was peeled off by 10 rubbing movements or less against the 2155~?2 specimen. The specimen No. 12 was not damaged by 10 rubbing movements or more against the specimen, and the specimens Nos. 13 and 14 were not damaged by 40 rubbing movements or more against the specimens.
The specimens Nos. 13 and 14 were not damaged by 40 rubbing movements or more against the specimens because necks were developed between TiOz particles, firmly joining them, since the firing temperature was higher than 800°C.
The specimen No. 11 was damaged and the photocata-lytic layer was peeled off by 10 rubbing movements or less against the specimen because the firing temperature was only 20°C higher than the softening temperature of the glass base, so that the viscosity of the glass base was not made sufficiently low, and hence the anatase Ti02 particles which made up the lowermost layer of the photocatalytic layer were not sufficiently embedded in the glass base.
The specimen No, 12 was not damaged by 10 rubbing movements or more against the specimens because though the firing temperature was not high enough to generate necks, the difference between the firing temperature and the sof-tening temperature of the glass base adjusted the viscosity of the glass base to a value which allowed TiOz particles to be adequately embedded in the glass base.
In the antibacterial test shown in Table 12, each of the specimens Nos. 11 - 13 had a good antibacterial value of +++ or ++, but the specimen No. 14 had an antibacterial value of -. This is because the Ti02 particles are of a ru-215~~22 tile structure and the sintering temperature was 320°C
higher than the softening temperature of the glass base and the viscosity of the glass base was so low that the TiOz par-ticles of the photocatalytic layer were embedded in the glass base.
(Inventive Example 19) An aqueous solution of 15 % of Ti02 sol was coated on a glass base having a size of 100 x 100 x 5 mm, which had different specific gravities for respective specimens, by spray coating, forming a Ti02 layer having a thickness of 0.8 ~.m. Then, the glass base with the TiOz layer formed thereon was placed in a ceramic mold with good mold releasability, and heated at 750°C by a roller-hearth kiln, and thereafter cooled and solidified into a multi-functional glass.
Changes in the antibacterial and wear-resistant capabilities of specimens of the above multi-functional glass as the specific gravity of the glass base varied are given in Table 13 below.
(Table 13) Photocatalyst = TiO
No. 15 16 17 18 Type of glass base SiO~-A1203- S1O2-AlzO3-Pb0 Pb0 Specific gravity of glass 5.3 3.8 2.8 2.4 base Specific gravity of Ti02 3.9 3.9 3.9 3.9 Softening temperature (C) 480 540 620 680 _ 87 _ ._ 21~5~?2 of glass base Firing temperature (C) 750 750 750 750 Antibacterial capability ++ +++ +++ +++

Wear resistance x O O O

In the antibacterial test, each of the specimens Nos. 15 - 18 had a good antibacterial value of +++. This is considered to result from the fact that the firing tempera-ture of each of the specimens Nos. 17 -- 20 was higher than the softening temperature of the glass base by 30°C or more or 300°C or less, and the difference between the firing tem-perature and the softening temperature of the glass base adjusted the viscosity of the glass base to a value which allowed Ti02 particles to be adequately embedded in the glass base.
With respect to the wear resistance, the photo-catalytic layer of the specimen No. 15 was damaged and peeled off by 5 rubbing movements or less against the speci-men, but the specimens Nos. 16 - 18 were not damaged by 10 rubbing movements or more against the specimens.
The reason for this appears to be that unlike the other specimens, the specific gravity of the glass base of the specimen No. 15 was greater than that of Ti02, and as a result, the anatase TiOZ particles making up the lowermost layer of the photocatalytic layer were not sufficiently em-bedded in the glass base.
Therefore, it was found out that the wear resis-tance of the multi-functional glass is affected by the spe-- 88 _ 2I5~~?2 cific gravities of the TiOz and the glass base, and is low-eyed if the specific gravity of the glass base is greater than the specific gravity of the TiOz.
(Inventive Example 20) After an aqueous solution composed of a stirred mixture of a TiOz sol and an SnOz sol was coated on the sur-face of a square glass base composed of Si02-A1203-Ba0 (softening temperature: 620°C) with eacr. side 150 mm long by spray coating. Thereafter, the assembly was fired at 750°C
and cooled and solidified into a multi-functional glass.
The concentration of the TiOZ sol was in the range of from 4 to 6 wt~, and the TiOz sol was adjusted to a pH of 11 by an aqueous solution of NH3. The crystal diameter of the Ti02 particles was 0.01 ~tm, and the crystal diameter of the Sn02 particles was 0.0035 ~.un.
The results of antibacterial and wear-resistant capability tests which were conducted on the multi-functional glass as the amount of SnOz (molar ratio) with respect to the total amount of TiOZ and Sn02 varied are given in Table 14 below.
(Table 14) Base = Si02-A1203-Ba0 glass, photocatalyst = TiOZ, Interstitial particles = SnO, (0.0035 dun) No. 19 20 21 22 23 Amount of SnOz (mol ~) 0 10 20 60 100 Antibacterial capability +++ +++ +++ ++ -Wear resistance O O O O O

_ 89 _ ._ 2~5~g22 The wear resistance increased as the amount of SnOz increased. When 10 % or more of SnOz was added, the specimens were not damaged and changed by 40 rubbing move-ments or more against the specimens.
When the added amount of SnOz was up to 20 %, the antibacterial value was +++ as was the case with no SnOz added. When the added amount of SnOz was 60 %, the antibac-terial value was ++_ When more SnOz was added, the probabil-ity that Sn02 covered the Ti02 particles on the surface of the glass base increased, resulting in a reduction in the antibacterial capability. When the added amount of SnOz was 100 %, the antibacterial value was -.
Therefore, the multi-functional glass can have excellent antibacterial and wear-resistant capabilities if the added amount of SnOz in terms of a molar ratio was 10 %
or more or 60 % or less, preferably, 10 % or more or 20 % or less of the total amount of TiOz and Sn02.
As the amount of Sn02 increases, the wear resis-tance of the multi-functional glass increases by the mecha-nism described above with reference to FIGS. 17(a) through 17(c).
As described above, if a composite material in-cluding a TiOz particle layer retained on the surface of a base by a glass base with Sn02 particles filling interstices between Ti02 particles exposed on the outermost surface is produced by being fired at a temperature of 600°C or higher, then the composite material has increased wear resistance as ~i5582~
necks between the Ti02 particles are joined without develop-ing cracks.
(Comparative Example 21) As with Inventive Example 20, an aqueous solution composed of a stirred mixture of a Ti02 sol and an SnO~ sol was coated on the surface of a square glass base of Si02-A1203-Ba0 (softening temperature: 620°C) with each side 150 mm long by spray coating. Thereafter, the assembly was fired at 750°C and cooled and solidified into a multi-functional glass.
The concentration of the Ti02 sol was in the range of from 4 to 6 wt%, and the TiOZ sol was adjusted to a pH of 11 by an aqueous solution of NH3. The crystal diameter of the TiOz particles was 0.01 ~tm as with Inventive Example 5, but the crystal diameter of the SnOz particles was 0.008 dun, slightly greater than that in Inventive Example 20.
The results of antibacterial and wear-resistant capability tests which were conducted on the multi-functional glass thus produced are given in Table 15 below.
(Table 15) Base = SiOz-A1203-Ba0 glass, photocatalyst = Ti02, Interstitial particles = SnO~ (0.0080 um), Heated at 750°C
No. 24 25 26 27 28 Amount of Sn02 (mol %) 0 10 20 60 100 Antibacterial capability +++ +++ +++ ++ -wear resistance O O O O O

.. 2155~?2 The effect which the Sn02 particles having a di-ameter of 0.008 dun had on the wear resistance was smaller than the SnOz particles having a diameter of 0.0035 ~tm. When 60 % or more (molar ratio) of Sn02 with respect to the total of Ti02 and Sn02 was added, the specimens were not damaged and changed by 40 rubbing movements or more against the specimens.
With respect to the antibacterial capability, when the added amount of Sn02 was up to 20 %, the antibacterial value was +++ as was the case with no Sn02 added. When the added amount of Sn02 was 60 %, the antibacterial value was ++. When more SnOZ was added, the probability that Sn02 cov-Bred the Ti02 particles on the surface of the glass base in-creased, resulting in a reduction in the antibacterial capa-bility. When the added amount of SnOZ was 100 %, the anti-bacterial value was -.
Therefore, when TiOz particles having a diameter of 0.01 dun are employed, it is difficult to produce a multi-functional glass which is excellent in both antibacterial and wear-resistant capabilities by adding SnOz particles hav-ing a diameter of 0.0035 ~tm. The reason for this appears to be that the vapor pressure of Sn02 particles decreases as the particle diameter increases, and whereas Sn02 particles hav-ing a diameter of 0.0035 Etm that remain unvaporized exist in the interstices between TiOz particles and are effective in increasing the bonding strength, SnOZ particles having a di-ameter of 0.008 ~tm do not enter the interstices between Ti02 ._ 2I55~22 particles, but are highly probably present on the Tio2 parti-cles because the Sn02 particles are greater than the inter-stices between Ti02 particles.
Consequently, the size of Sn02 particles to fill the interstices between TiOZ particles should preferably 4/5 or less of the size of the Ti02 particles.
(Inventive Example 22) An aqueous solution of TiOz sol was coated on the surface of a square glass base of Si02-A1203-Ba0 (softening temperature: 620°C) with each side 150 mm long by spray coating. Thereafter, the assembly was fired at 750°C and cooled and solidified into a composite material. An aqueous solution of SnOZ sol was coated on the composite material, and the assembly was then heated at 110°C, thereby producing a multi-functional glass. The aqueous solution of TiOZ sol was the same as that used in Inventive Example 20, and the aqueous solution of SnOz sol contained Sn02 particles having a diameter of 0.0035 N,m.
The results of antibacterial and wear-resistant capability tests which were conducted on the multi-functional glass thus produced are given in Table 16 below.
(Table 16) Base = Si02-A1203-Ba0 glass, photocatalyst = Ti02, Interstitial particles = SnOz (0.0035 um), Heated at 750°C/110°C
No. 29 30 31 32 33 Amount of Sn02 (mol %) 0 10 20 60 100 .~ 2I55~22 Antibacterial capability +++ +++ +++ ++ -[Wear resistance O O 0 I O I O I

The wear resistance increased as the added amount of Sn02 increased. When 20 % or more (molar ratio) of Sn02 was added, the specimens were not damaged and changed by 40 rubbing movements or more against the specimens.
With respect to the antibacterial capability, when the added amount of Sn02 was up to 20 %, the antibacterial value was +++ as was the case with no Sn02 added. When the added amount of SnOz was 60 %, the antibacterial value was ++. When more Sn02 was added, the probability that Sn02 cov-ered the Ti02 particles on the surface of the glass base in-creased, resulting in a reduction in the antibacterial capa-bility. When the added amount of SnOZ was 100 %, the anti-bacterial value was -.
Since the SnOZ sol was heated at a low temperature of 110°C, the assembly was not sintered according to the vaporization - condensation mechanism described above in Inventive Example 6. Nevertheless, the wear resistance in- , creased because the bonding between Ti02 particles was strengthened by Sn02 particles, which had a diameter smaller than the Ti02 particles, i.e., had a greater specific surface area and a higher adsorbing power, filled the interstices between the TiOZ particles.
(Inventive Example 23) An aqueous solution of Ti02 sol was coated on the surface of a square glass base of SiOz-A1~03-Ba0 (softening _._ 215522 temperature: 620°C) with each side 150 mm long by spray coating. Thereafter, the assembly was fired at 750°C and cooled and solidified into a composite material. An aqueous solution of copper acetate was coated on the composite mate-rial and then dried, after which the assembly was irradiated with light containing ultraviolet rays to fix copper ions to a photocatalytic layer while reducing the copper ions, thereby producing a multi-functional glass. The assembly was irradiated with light by a mercury lamp.
The size of the particles of Cu fixed to the pho-tocatalytic layer was about 0.004 ~tia on the average.
The results of antibacterial and wear-resistant capability tests which were conducted on the multi-functional glass thus produced are given in Table 17 below.
(Table 17) Base = SiOZ-A1203-Ba0 glass, photocatalyst = TiOz, Interstitial particles = Cu (0.004 dun), Heated at 750°C/photoreduced No. 34 35 36 37 38 Amount of Cu (mol %) 0 10 20 60 100 Antibacterial capability +++ +++ +++ +++ +++

Wear resistance O O O O O

The wear resistance increased as the added amount of Cu increased. When 20 % or more (molar ratio) of Cu was added, the specimens were not damaged and changed by 40 rub-bing movements or more against the specimens.

21~5~?2 With respect to the antibacterial capability, when the added amount of Cu was up to 20 ~, the antibacterial value was +++ as was the case with no Cu added. Since Cu has an antibacterial capability itself, no reduction in the antibacterial capability was appreciated when Cu was added in a large amount.
However, it can be considered that if the added amount of Cu is small, then the pl:otocatalytic action of the TiOZ particle layer is prevalent, and if the added amount of Cu is large, then the action of Cu is prevalent. If only the action of Cu is relied upon, then its service life ap-pears to be shorter than if no photocatalyst were present because Cu is gradually eluted when used in a liquid. Since Cu added in a large amount results in an increased cost, it appears meaningless to unduly increase the added amount of Cu.
Inventive Example 23 confirmed that not only par-ticles of an oxide such as Sn02, but also particles of a metal such as Cu can be used as particles to fill the inter-stices in the Ti02 particle layer.
(Inventive Example 24) An aqueous solution of Ti02 sol was coated on the surface of a square glass base of Si02-A1203-Ba0 (softening temperature: 620°C) with each side 150 mm long by spray coating. Thereafter, the assembly was fired at 950°C and cooled and solidified into a composite material. An aqueous solution of copper acetate was coated on the composite mate-2I55$~2 rial, after which the assembly was irradiated with light containing ultraviolet rays to fix copper ions to a photo-catalytic layer while reducing the copper ions, thereby pro-ducing a multi-functional glass.
The assembly was irradiated with light for several minutes by a BLB lamp. The Ti02 structure underwent a phase transition from an anatase structure to a rutile structure in the heat treatment. The film thickness of Ti02 was ad-justed to 0.4 um upon spray coating.
Antibacterial and wear-resistant capability tests were conducted on the multi-functional glass thus manufac-tured. The wear resistance of the multi-functional material was good in the temperature range even if no Cu was added.
When Cu was added, the specimens were not damaged and changed by 40 rubbing movements or more against the speci-mens as was the case with no Cu added.
The results of the antibacterial test are shown in FIG. 22. When no Cu was added, the antibacterial capability had a poor value of + because the Ti02 was of the rutile structure. As Cu was added, the antibacterial capability increased. Irrespective of whether irradiated with the BLB
lamp or not, the antibacterial activity had a value of ++ if the carried amount of Cu was 0.7 ~.g/cm2 or greater, and a value of +++ if the carried amount of Cu was 1.2 ~.g/cm2 or greater.
It can be seen from the foregoing that for produc-ing a multi-functional glass which is excellent in both an-v 2I5~8~~
tibacterial and wear-resistant capabilities, the carried amount of Cu should be 0.7 ~.g/cm2 or greater, and more pref-erably 1.2 ~tg/cm2 or greater.
The carried amount of Cu is greatly increased if a drying step is included after the aqueous solution of copper acetate is coated and before the assembly is irradiated with the BLB lamp. The relationship is shown in FIG. 23. This is because the concentration of metal ions when they are photoreduced is made higher by being dried.
The carried amount of Cu is maximized when the coated amount of Cu is optimized, as shown in FIG. 24 which illustrates the use of copper acetate containing 1 wt % of Cu. In order to make the coated amount of Cu equal to 0.7 ~tg/cm2 or greater in FIG. 24, the carried amount of Cu may be equal to or greater than 0.2 mg/cmz or equal to or smaller than 2.7 mg/cmZ. In order to make the coated amount of Cu equal to 1.2 ~tg/cm2 or greater in FIG. 24, the carried amount of Cu may be equal to or greater than 0.3 mg/cm2 or equal to or smaller than 2.4 mg/cm2.
(Inventive Example 25) An aqueous solution of Ti02 sol was coated on the surface of a square glass base of SiOz-A1203-Ba0 (softening temperature: 680°C) with each side 150 mm long by spray coating. Thereafter, the assembly was fired at 950°C and cooled and solidified into a composite material. An aqueous solution of silver nitrate was coated on the composite mate-rial and dried, after which the assembly was irradiated with _ 98 _ light containing ultraviolet rays to fix silver ions to a photocatalytic layer while reducing the silver ions, thereby producing a multi-functional glass.
The assembly was irradiated with light for several minutes by a BLB lamp. The Ti02 structure under'aent a phase transition from an anatase structure to a rutile structure in the heat treatment. The film thickness of Ti02 was ad-justed to 0.4 ~t.m upon spray coating.
Antibacterial and wear-resistant capability tests were conducted on the multi-functional glass thus manufac-tured. The wear resistance of the multi-functional material was good in the temperature range even if no Cu was added.
When Ag was added, the specimens were not damaged and changed by 40 rubbing movements or more against the speci-mens as was the case with no Ag added.
The results of the antibacterial test are shown in FIG. 25. When no Ag was added, the antibacterial capability had a poor value of + because the Ti02 was of the rutile structure. As Ag was added, the antibacterial capability increased. Irrespective of whether irradiated with the BLB
lamp or not, the antibacterial activity had a value of ++ if the carried amount of Ag was 0.05 ~tg/cmZ or greater, and a value of +++ if the carried amount of Ag was 0.1 ~.g/cm2 or greater.
For producing a multi-functional glass which is excellent in both antibacterial and wear-resistant capabili-_ 99 _ ~.- 215822 ties, therefore, the carried amount of Ag should be 0.05 ~.g/cm2 or greater, and more preferably 0.1 pg/cmz or greater.
If the carried amount of Ag is large, the multi-functional material is colored with brown or black, result-ing in an unsightly appearance. However, the multi-functional material is not colored if the carried amount of Ag is 1 ~.g/cm2 or smaller.
It can be understood from the foregoing that the carried amount of Ag should be equal to or greater than 0.05 ~tg/cm2 or equal to or smaller than 1 ~tg/cmz, and more pref-erably equal to or greater than 0.1 ~g/cm2 or equal to and smaller than 1 ~tg/cm2.
(Inventive Example 26) An aqueous solution of Ti02 sol was coated on the surface of a square glass base of Si02-A1z03-Ba0 (softening temperature: 680°C) with each side 150 mm long by spray coating. Thereafter, the assembly was fired at 950°C and cooled and solidified into a composite material. An aqueous solution of silver nitrate was coated on the composite mate-rial and dried, after which the assembly was irradiated with light containing ultraviolet rays to fix silver ions to a photocatalytic layer while reducing the silver ions, thereby producing a multi-functional glass.
The assembly was irradiated with light for several minutes by a BLB lamp. The Ti02 structure underwent a phase transition from an anatase structure to a rutile structure in the heat treatment.

2 i 55822 Antibacterial and wear-resistant capability tests were conducted on the multi-functional glass thus manufac-tured while changing the film thickness of Ti02 to various values.
The wear resistance of the multi-functional mate-rial was good in the TiOz film thickness range of 2 ).tm or below which was tested. No specimens were damaged and changed by 40 rubbing movements or more against the speci-mens.
The antibacterial capability had a value of ++
when the film thickness was 0.1 ).tm or more, and a value of +++ when the film thickness was 0.2 ).un or more. Therefore, the film thickness of TiOz should be 0.1 Etm or more, and more preferably be 0.2 ~.m or more. _ As described above, photocatalytic particles are fixed to a thermoplastic base, and photocatalytic particles making up a surface layer of a photocatalytic layer are not embedded in the binder layer. Therefore, the photocatalytic particles of the surface layer have surfaces exposed for sufficiently performing their photocatalytic effect. Those photocatalytic particles which make up a lower layer of the photocatalytic layer are partly embedded in the thermoplas-tic base, so that the photocatalytic layer is retained under increased retentive forces against peel-off.
FIGS. 26 and 27 show basic profiles of a section of a mufti-functional material as it is observed by EPMA
(electron-prove microanalyzer). As can be understood from v - 101 -a 2I55~?2 FIGS. 26 and 27, the concentration of the component of the photocatalytic layer 2 remains substantially constant in a region (region A) from the surface exposed to the atmos-phere, and then the component of the photocatalytic layer 2 is reduced. The component of the amorphous layer (binder layer) is not present or little on the surface, and its con-centration increases into the multi-functional material and becomes substantially constant in a region (regior. B) when a certain film thickness is reached. The region A is defined as the photocatalytic layer, the region B as the amorphous layer, and an intermediate region C as an intermediate layer. The basic profile shown in FiG. 26 is of a concep-tual nature for illustration. Actually, as shown in FIG.
27, the basic profile tends to have changes caused by manu-facturing steps in the concentrations which have been de-scribed as constant as shown in FIG. 26. In the actual ba-sic profile shown in FIG. 27, portions where the concentra-tions of regions (regions A', B') corresponding to the con-stant regions in FIG. 26 reach minimum values are regarded as boundaries between regions A', C' and regions B', C'.
The thickness of the photocatalytic layer is the thickness of the region A or the region A', and the thick-ness of the intermediate layer is the thickness of the re-gion C or the region C'.
The thickness of the intermediate layer can be varied by controlling the speed at which and the time in which photocatalytic particles can move into the amorphous ~~~~~22 layer that is being softened. The speed can be controlled based on the difference between specific gravities of the photocatalytic particles and the amorphous layer, the firing temperature, the atmospheric pressure, etc., and the time can be controlled by varying the retention time at the tem-perature at which the amorphous material is softened.
The adhesiveness between the layers can be in-creased if the thickness of the intermediate layer is 1/3 or more of the thickness of the photocatalytic layer.
Specific examples will be described below.
(Inventive Example 27) After an amorphous layer composed of Si02-A1203-Na/Rz0 was formed on the surface of a square alumina base with each side 10 cm long by spray coating and then dried and fired, an aqueous solution of TiOz sol having an average particle diameter of 0.01 dun was coated on the amorphous layer by spray coating and fired at 850°C while varying re-tention times, forming anatase Ti02 layers having respective thicknesses of 0.2 dun, 0.5 ~tm, 1 Eun. Then, an aqueous solu-tion of copper acetate was coated on the anatase Ti02 layers by spray coating, and thereafter photoreduced by a light source comprising a 20W BLB lamp for 30 seconds, thus pro-ducing specimens. The light source was spaced from the specimens by a distance of 10 cm. An elementary analysis (Ti, Si) was conducted on sections of the produced specimens with EPMA to measure their film thicknesses and evaluate their antibacterial and wear-resistant capabilities.

~,_ 2155~~2 The antibacterial capability of the specimens was tested using escherichia coli, strain: W3110. Specifically, 0.15 ml (1 - 5 x 10° CFU) of the bacterial solution was dropped onto the outermost surface of the multi-functional material which had been sterilized with 70 % ethanol, and a glass sheet (100 x 100 mm) was placed in intimate contact with the outermost surface of the base, thus preparing a specimen. After the specimen was irradiated with light from a white-light lamp with 3500 luxes for 30 minutes, the bac-terial solution on the irradiated specimen was wiped with a sterile gauze, and collected in 10 ml of physiological sa-line. The survival rates of the bacteria were determined as indications for evaluation. The evaluation indications are the same as those shown in Table 1.
The results of the evaluation are shown in Table 18 below. All the specimens had an antibacterial value of +++ and a good wear-resistant value of O or O. Those specimens in which the ratio of the thickness of the inter-mediate layer to the thickness of the photocatalytic layer is 1/3 or greater all had a wear-resistant value of O.
(Table 18) TiOZ film Inter- Retention Inter- Anti- Peeling thickness mediate time mediate bacterial resist-(Nm) layer (hours) layer/ value ance thickness Ti02 film ( Etm ) thicknes s 1 0.42 ~ 16 ~ 0.42 ~ +++ ~ O

2155'22 1 0.33 2 0.33 +++ O

1 0.30 1 0.30 +++ O

0.5 0.17 2 0.34 +++ O

0.5 0.13 1 0.26 +++ O

0.2 0.08 2 0.40 +++ O

0.2 0.05 1 0.25 +++ O

1 0 0 +++ a (Comparative Example 28) A dispersion in ammonia of Ti02 sol having an av-erage diameter of 0.01 dun was coated on a square alumina base with each side 10 cm long by spray coating and then fired at 850°C, forming a thin anatase Ti02 film having a film thickness of 1 ~.m. Then, an aqueous solution of copper acetate was coated on the thin anatase Ti02 film by spray coating, and thereafter photoreduced by a light source com-prising a 20W BLB lamp for 30 seconds, thus producing a specimen. The light source was spaced from the specimen by a distance of 10 cm. The specimen was evaluated for its antibacterial and wear-resistant capabilities.
The specimen had a good antibacterial value of +++
and but an insufficient wear-resistant value of e.
As described above, in a multi-functional material having photocatalytic functions, which is composed of a pho-tocatalytic layer supported on the surface of a base through an amorphous layer, the photocatalytic layer having an upper layer exposed to ambient air and being composed of photo-catalytic particles joined together, the photocatalytic _ 2I55~?2 layer and the base can be held in greater intimate contact with each other for resistance against peeling by an inter-mediate layer disposed between the amorphous layer and the photocatalytic layer with the concentrations of the compo-nents of the amorphous layer and the photocatalytic layer varying continuously in the intermediate layer. The adhe-siveness between the layers can be increased if the thick-ness of the intermediate layer is 1/3 or mere of the thick-ness of the photocatalytic layer.
The formation of the photocatalytic layer 2 by sintering will be described below. FIG. 1(a) shows conven-tional Ti02 particles before they are fired, and FIG. 1(b) shows the conventional TiOz particles after they are fired.
When a sol containing Ti02 particles is coated on the surface of a base 1 as shown in FIG. 1(a), and the assembly is heated (sintered) for increasing the film strength, a crack 2a is liable to develop as shown in FIG. 1(b).
The reasons for the development of the crack are that a phase transition to a rutile structure causes a vol-ume shrinkage (a density increase), and whereas the distance between Ti02 particles 101 is Lo as shown in FIG. 2(a) before being fired, the distance is reduced to L1 (L1 < Lo) as shown in FIG. 2(b) due to volumetric diffusion of the particles into each other after being fired into the rutile structure.
According to the present invention, Sn02 is con-densed on necks between Ti02 particles 3 that are joined by sintering, thickening the necks thereby to strengthen the ._ ~I558?2 bonding between the Ti02 particles 3 and accordingly increase the film thickness.
To form the above photocatalytic layer 2, an Sn02 sol is mixed with a Ti02 sol, and the mixture is stirred and then coated on the base 1, after which the assembly is heated (sintered) in a predetermined temperature range.
The concentration of the Ti02 sol is in the range of from 4 to 6 wt%, ar.3 the Ti02 sol is adjusted to a pH of 11 by an aqueous solution of NH3. The concentration of the Sn02 sol is about 10 wt%, and the Sn02 sol is adjusted to a pH of 11 by an aqueous solution of NH3. The Sn02 particles have an average primary particle diameter of 0.0035 Vim, which is a crystal size (primary particle) determined from the half-width of diffraction lines of XRD (X-ray diffrac-tion).
Since Sn02 has a vapor pressure higher than that of TiOz, the distance between the TiOz particles 3 is Lo be-fore sintering as shown in FIG. 17(a). The vapor pressure is higher at the surfaces of the Ti02 particles 3 which have a positive curvature, and lower at surfaces having a nega-tive curvature, i.e., the surface of a neck where the Ti02 particles 3 abut against each other. As a result, as shown in FIG. 17(b), SnOZ having a vapor pressure higher than that of Ti02 enters the neck, and is condensed as shown in FIG.
17(c). The assembly is thus sintered by a vaporization -condensation mechanism.

._ 2155822 When the assembly is sintered by a vaporization -condensation mechanism, the distance LZ between the Ti02 par-ticles after being sintered is substantially the same as the distance Lo before sintering, and hence no crack is devel-oped.
In order to keep the distance between the Ti02 particles substantially unchanged after being sintered and also to cause the photocatalytic layer to have a photoactiv-ity (R3o) of 50 ~ or more, it is necessary that the propor-tion (internal ratio) of SnOz with respect to Ti02 be in the range of from 20 to 70 ~ as shown in FIG. 28.
The proportions represent respective weight ratios of solid materials contained in the respective sols. The photoactivity was evaluated based on the decomposition of methyl mercaptan, using the removal ratio (R3o) 30 minutes after being irradiated with light as an indication. Spe-cifically, a square tile coated with a photocatalytic layer, with each side 150 mm long, was placed in a glass container of 11 liters at a distance of 8 cm from a light source (4W
BLB fluorescent lamp), and a methyl mercaptan gas was intro-duced into the glass container until it reaches a concentra-tion of 3 to 5 ppm in the glass container. After no adsorp-tion in the dark was confirmed, the fluorescent lamp was turned on, and the concentration was measured for changes with time by gas chromatography. The removal ratio (R3o) is expressed by:
R30 (x0 x30) ~~ X 10~

215~~22 where xo is the initial concentration [ppm] and x3o the con-centration (ppm] 30 minutes later.
The film strength was evaluated by rubbing the specimens with a plastic eraser and comparing changes in the appearance of the specimens. Evaluation indications are the same as the evaluation indications in Table 1.
FIG. 29 is a graph showing the relationship be-tween the heat-treatment temperature and the photoactivity.
When an organic stabilizer is added, the photoactivity is lowered. Irrespective of whether an organic stabilizer is added or not, the temperature for heat treatment ranges from 300 to 850°C. If the temperature were lower than 300°C, then photoactivity would be difficult to develop, and if the temperature exceeded 850°C, the structure of Ti02 would change from an anatase structure to a rutile structure.
As described above, when a sol containing titanium oxide particles and a substance whose vapor pressure is higher than that of titanium oxide is coated on a tile or the like and sintered, a film is formed on the tile by a vaporization - condensation mechanism. Therefore, the dis-tance between the titanium oxide particles remains substan-tially the same after being sintered, making the film resis-tant to cracks. Since Sn02 or the like is condensed on necks between titanium oxide particles, the peel strength of the film is increased.
When the added amount of Sn02 or the like (in terms of its internal ratio with respect to Ti02 is in the range of from 20 to 70 ~, both the film strength and the photoactivity are satisfied. A sufficient level of photoac-tivity can be achieved when the assembly is heated in a tem-perature range from 300 to 850°C.
The process of measuring R3o by gas chromatography requires an expensive measuring apparatus and is of poor efficiency as only one sample can be measured by one measur-ing apparatus.
Though it is known that photoactivity can be in-creased by having TiOz carry a metal such as Pt or the like, it is difficult to determine the net photoactivity of a thin photocatalytic film of such a structure because of the ad-sorption of a gas by the metal.
After tiles have been installed on a wall surface, the photoactivity of thin photocatalytic films on the tiles cannot be measured by gas chromatography.
One process of estimating the photoactivity not by gas chromatography is to check the survival rate of bacteria which will be killed by a photocatalyst, after being irradi-ated with light. However, the process is more cumbersome to carry out than gas chromatography, and makes it difficult to determine the net photoactivity because bacteria can be killed by the antibacterial power of a metal itself which is carried by a thin photocatalytic film. For these reasons, one of the following processes of measuring the photoactiv-ity of a thin photocatalytic film may be employed.

2155~?2 According to a first process, an aqueous solution of alkali halide such as potassium iodide, potassium chlo-ride, or the like is dropped onto the surface of a thin pho-tocatalytic film composed primarily of TiOz which is formed on the surface of a base, and then the dropped aqueous solu-tion of alkali halide is irradiated with ultraviolet rays for a given period of time. The magnitude of the photoac-tivity of the thin photocatalytic film is determined based on the difference between the pH of the aqueous solution of alkali halide before it is irradiated and the pH of the aqueous solution of alkali halide after it is irradiated.
According to a second process, a mixture of an aqueous solution of alkali halide such as potassium iodide, potassium chloride, or the like and a pH indicator is dropped onto the surface of a thin photocatalytic film com-posed primarily of TiOZ which is formed on the surface of a base, and then the dropped mixture is irradiated with ultra-violet rays for a given period of time. The magnitude of the photoactivity of the thin photocatalytic film is deter-mined based on a change in the color of the mixture.
According to a third process, a photoactivity measuring film is held in intimate contact with the surface of a thin photocatalytic film composed primarily of TiOz which is formed on the surface of a base, and then the pho-toactivity measuring film is irradiated with ultraviolet rays for a given period of time. The magnitude of the pho-toactivity of the thin photocatalytic film is determined based on a change in the color of the photoactivity measur-ing film.
FIG. 30 shows first and second processes of meas-uring the photoactivity. A photocatalytic layer 2 composed primarily of Ti02 is formed on the surface of a base 1. It is possible to employ a process of measuring the photoactiv-ity of a thin photocatalytic film such as the photocatalytic layer.
According to a first process, an aqueous solution of alkali halide such as potassium iodide, potassium chlo-ride, or the like is dropped onto the surface of a thin pho-tocatalytic film composed primarily of Ti02 which is formed on the surface of a base, and then the dropped aqueous solu-tion of alkali halide is irradiated with ultraviolet rays for a given period of time. The magnitude of the photoac-tivity of the thin photocatalytic film is determined based on the difference between the pH of the aqueous solution of alkali halide before it is irradiated and the pH of the aqueous solution of alkali halide after it is irradiated.
According to a second process, a mixture of an aqueous solution of alkali halide such as potassium iodide, potassium chloride, or the like and a pH indicator is dropped onto the surface of a thin photocatalytic film com-posed primarily of Ti02 which is formed on the surface of a base, and then the dropped mixture is irradiated with ultra-violet rays for a given period of time. The magnitude of .~ 2155~?2 the photoactivity of the thin photocatalytic film is deter-mined based on a change in the color of the mixture.
According to a third process, a photoactivity measuring film is held in intimate contact with the surface of a thin photocatalytic film composed primarily of Ti02 which is formed on the surface of a base, and then the pho-toactivity measuring film is irradiated with ultraviolet rays for a given period of time. The :magnitude of the pho-toactivity of the thin photocatalytic film is determined based on a change in the color of the photoactivity measur-ing film.
FIG. 30 shows first and second processes of meas-uring the photoactivity. A photocatalytic layer 2 composed primarily of Ti02 is formed on the surface of a base 1. To check whether the photocatalytic layer 2 has photoactivity or not, an aqueous solution 30 of alkali halide such as po-tassium iodide, potassium chloride, or the like is dropped onto the surface of the photocatalytic layer 2, and then the dropped aqueous solution 30 of alkali halide is irradiated with ultraviolet rays for a given period of time by an ul-traviolet lamp 40. The magnitude of the photoactivity of the photocatalytic layer 2 is determined based on the dif-ference between the pH of the aqueous solution of alkali halide before it is irradiated and the pH of the aqueous solution of alkali halide after it is irradiated.
FIG. 33 is a graph showing the relationship be-tween the time of ultraviolet irradiation and the pH change.

The test was conducted under the conditions that the dropped aqueous solution 30 of alkali halide had a concentration of 0.1 mol/1, the ultraviolet lamp 40 was a 20W BLB fluorescent lamp, the photocatalytic layer 2 and the ultraviolet lamp 40 were spaced from each other by a distance of 20 cm, and the aqueous solution 30 of alkali halide was irradiated for 60 minutes.
It can be seen from FIG. 33 that irrespective of whether the photocatalytic layer 2 is of an anatase struc-ture, a metal-carrying structure, or a rutile structure, the pH of the aqueous solution 30 of alkali halide increases until the time of ultraviolet irradiation reaches 30 min-utes.
The pH of the aqueous solution 30 of alkali halide increases upon being irradiated with ultraviolet rays be-cause the following oxidizing and reducing reactions occur at the same time, with OH' (hydroxide ions) produced by the reducing reaction.
Oxidizing reaction: 2I' + 2h~ = IZ
Reducing reaction: OZ + 2H~0 + 4e' - 40H-Therefore, if the pH of the aqueous solution 30 of alkali halide increases upon being irradiated with ultravio-let rays, then the photocatalytic layer 2 can be said to have photoactivity.
FIG. 34 is a graph showing the relationship be-tween R,o and the pH change. R3a represents the proportion (%) of a gas such as methyl mercaptan or the like which is 215$22 reduced 30 minutes after being irradiated with ultraviolet rays. It can be understood from FIG. 34 that R3o and the pH
change have a positive correlation to each other. There-fore, any change in pH serves as an indication as to whether there is photoactivity or not.
In the above first process, a change in pH is measured by a pH meter or a pH measuring sheet. In the sec-ond process, the mixture of the aqueous solution 30 of al-kali halide such as potassium iodide, potassium chloride, or the like and the pH indicator is dropped onto the surface of the photocatalytic layer 2, and then the dropped mixture is irradiated with ultraviolet rays for a given period of time.
The magnitude of the photoactivity of the photocatalytic layer 2 is determined based on a change in the color of the mixture.
The pH indicator may suitably be methyl red be-cause the pH of the aqueous solution 30 of alkali halide before being irradiated with ultraviolet rays is about 4.5 and the pH of the aqueous solution 30 of alkali halide after being irradiated with ultraviolet rays is in the range of from 5.5 to 6.5.
According to the first and second processes, the aqueous solution 30 of alkali halide or the mixture of the aqueous solution 30 of alkali halide and the pH indicator is dropped onto the surface of the photocatalytic layer 2.
However, the dropped liquid may spread in different patterns .~ 215522 on different bases, and the reactive area may differ from base to base.
Such a drawback can be eliminated by a process shown in FIG. 31. According to this process, after an aque-ous solution 30 of alkali halide is dropped onto the surface of a photocatalytic layer 2, the aqueous solution 30 of al-kali halide is pressed to a certain thickness and prevented from being dried by a transparent sheet 60 such as a glass sheet or the like.
A liquid such as the aqueous solution 30 of alkali halide is used on the condition that the surface of the base 1 lies horizontal, and cannot be used to determine the pho-toactivity of a thin photocatalytic film formed on a verti-cal surface such as an existing wall surface or a ceiling surface.
A process shown in FIG. 32 serves to eliminate such a shortcoming. According to this process, an activity measuring film 70 is held in intimate contact with the sur-face of a photocatalytic layer 2 formed on the surface of a base 1, and then irradiated with ultraviolet rays. The mag-nitude of the photoactivity of the photocatalytic layer 2 is determined based on a change in the color of the photoactiv-ity measuring film 70.
The photoactivity measuring film 70 may be pre-pared by drying a mixture of an organic binder, an aqueous solution of alkali halide such as potassium iodide, potas-215~~~2 sium chloride, or the like, and a pH indicator, and shaping the dried mixture into a film.
The porosity of the photocatalytic layer 2 will be considered below. The porosity represents the ratio of open pores, and should be 10 % or greater and less than 40 %, and preferably 10 or greater and 30 % or smaller.
The crystal diameter of the photocatalytic parti-cles should be less than 0.1 ~.m, and preferably of 0.04 dun or less. The film thickness of the photocatalytic layer may be of 0.1 Eun because the smaller the crystal diameter, the larger the effective area for reaction per unit volume.
When necks are produced by firing photocatalytic particles by way of solid-state sintering for increased layer strength, the crystal diameter increases to 0.1 Eun or greater, resulting in a reduction in the effective area for reaction per unit volume. Therefore, the film thickness should be of 0.5 ~tm or greater, and preferably of 0.6 dun or greater.
Particles having a crystal diameter of less than 0.01 ~tm, preferably of 0.008 ~tm or less, may be added be-tween the photocatalytic particles of a photocatalytic layer formed on the surface of a base. The added particles are effective in filling the interstices between the photocata-lytic particles, thus increasing the particle packing ratio and the surface smoothness for an increased film thickness against shearing stresses. The increased surface smoothness makes the surface resistant to stains. Though the increased 2155822.
surface smoothness results in a reduction in the porosity, since the pores to be filled are large enough to accommodate particles whose crystal diameter is of less than 0.01 elm, preferably of 0.008 Eun or less, the pores are large compared with the size (several ~) of the particles of a gas, and do not affect the deodorizing capability.
The particles whose crystal diameter is of less than 0.01 dun, prezerably of 0.008 ~,tm or less may be basi-cally of any of various types. However, since they may pos-sibly cover surfaces of photocatalytic particles as well as fill the interstices therebetween, the particles should preferably be o~f an oxide semiconductor such as Ti02, Sn02, ZnO, SrTi03 , Fe.,03, Biz03, W03, or the like which will not im-pair the photocatalytic activity, or a metal such as Ag, Cu, or the like. The particles whose crystal diameter is of less than 0.01 Eun, preferably of 0.008 ~tm or less may be added in any of: various processes. For example, such ul-trafine particles may be produced by a hydrothermal process or the like anct dispersed into a solution, generating a sol, .
and the sol may be coated on a photocatalytic layer by spray coating and heated at a temperature that is low enough not to cause grain growth, evaporating an organic dispersing agent. Alternatively, an alkoxide or an organic metallic salt may be coated on a photocatalytic layer, and heated to evaporate a di7_uent, an organic component, etc.
Furtlher alternatively, metal particles smaller than pores in a photocatalytic layer formed on the surface 2~.55~~2 of a base may be fixed in the photocatalytic layer. The metal particles thus fixed in the photocatalytic layer have an electron-capituring effect to increase the photocatalytic activity for a ~~reater deodorizing capability than if only the photocatalyitic layer is present.
The metal particles may be of any metal insofar as they can capture electrons. For example, the metal parti-cles may be made of Cu, Ag, Pt, or the like.
The metal particles are required to have an aver-age particle diameter smaller than the average diameter of the pores in the photocatalytic layer. The average diameter of the pores in the surface of the photocatalytic layer is required to be :smaller than the diameter of photocatalytic particles because the average diameter of the pores are sub-stantially equa:L to the diameter of photocatalytic particles in specimens whose porosity is 10 % or greater and less than 40 %, as obseived by an electron microscope. Preferably, the average diameter of the pores should be smaller than the diameter of photocatalytic particles of a starting material.
Since the starting material of a photocatalytic layer is generally of a particle diameter of 0.05 Etm or less, the average diameter of the pores should be of 0.05 ~.tm or less.
(Inventive Example 28) A colloidal suspension in ammonia of Ti02 sol hav-ing a crystal diameter of 0.01 ~tzn was coated, in different amounts for respective specimens, on a square tile base with each side 15 cm long by spray coating and then fired at a ~_ 21~~~22 temperature of 700°C or higher and 900° or lower, forming a photocatalytic layer. The produced specimens were evaluated for crystal diameters of anatase Ti02 particles, porosities on the layer surfaces, and deodorizing, wear-resistant, and peeling-resistant capabilities.
The deodorizing capability was evaluated by meas-uring R3o(L) which represents a removal ratio after being irradiated with light. Specifically, a specimen surface coated with a thin photocatalytic film is placed in a glass container of 11 liters at a distance of 8 cm from a light source (4W BLB fluorescent lamp), and a methyl mercaptan gas is introduced into the glass container until it reaches an initial concentration of 3 to 5 ppm in the glass container.
Changes in the .concentration are measured when the specimen is irradiated with light from the light source for 30 min-utes.
The wear resistance was evaluated by rubbing the specimens with .a plastic eraser and comparing changes in the appearance of t:he specimens. Evaluation indications are the same as the evaluation indications described above, and in-dicated below.
O : Not varied after 40 reciprocating rubbing movements against the specimens.
O . Damage wa~~ caused and the photocatalytic layer (Ti02 film) was peeled off by 10 or more and less than 40 rubbing movements against the specimens.
0 : Damage was caused and the photocatalytic layer (Ti02 ._ 21~ i822 film) was peeled off by 5 or more and less than 10 rubbing movements against the specimens.
x . Damage was caused and the photocatalytic layer (Ti02 film} was peeled off by less than 5 rubbing movements or less against the specimens.
The Feeling-resistant capability test is a test conducted under conditions stricter than those of the wear-resistant capability test, and uses a typewriter eraser (LION TYPEWRITER ERASER 502) which applies greater shearing forces, rather than a plastic eraser. Specifically, the surface of a specimen is rubbed 20 times under equal forces by a typewriter eraser, and its damaged or scratched condi-tion and a standard sample are visually compared with each other. Evaluation indications are given below.
O . Not changE~d at all.
O . A slight change is confirmed depending on the intensity of light applied to the specimen.
O : A slight change is confirmed.
x . A change is confirmed at sight.
The results are shown in FIGS. 35 through 37.
FIG. 35 shows the relationship between the poros-ity, the deodorizing ability, and the wear resistance at the time the thickness of a thin photocatalytic film is 0.8 ~.un.
The deodorizing ability increased with the porosity, and exceeds 50 % when the porosity was 10 %, and reached 80 % or more when the porosity was 30 %. Conversely, the wear-resistant capability had a value of O when the porosity was 2155~?2 up to 30 %, a value of O when the porosity was 40 %, and a value of O or x: when the porosity exceeded 40 %. It can be seen from the above results that in order to produce a mate-rial which has both deodorizing and wear-resistant capabili-ties, it is necessary for a thin photocatalytic film to have a porosity of 10 % or more and less than 40 %, preferably 10 % or more and 30 % or less.
FIG. 36 shows the deodorizing ability as it de-pends on the film thickness when the crystal diameter of photocatalytic particles making up a thin photocatalytic film whose porosity ranges from 20 to 30 % is varied. When the crystal diameter was of 0.1 ~.un, the deodorizing capabil-ity R3o(L) depended on the film thickness, and was lowered as the thickness of the thin photocatalytic film was reduced.
When the film thickness was of 0.04 ~tm or less, no depend-ency on the film thickness was seen. The deodorizing capa-bility was good when the film thickness was of 0.1 Elm. It can be understood from the above results that if the crystal diameter of photocatalytic particles is less than 0.1 Vim, preferably of 0.04 ~tm or less, then a good deodorizing capa-bility can be maintained even when the thickness of the thin photocatalytic film is reduced to about 0.1 Eun.
FIG. 37 shows the deodorizing and peeling-resistant capabilities as they depend on the film thickness when the crystal diameter and joined state of photocatalytic particles making up a thin photocatalytic film whose poros-ity ranges from 20 to 30 % are varied. When a required me-215a~22 chanical strength increased to the level of the peeling-resistant capability test, the wear-resistant capability of specimens with no necks had a value of O or x. In order to produce a mechanically sufficient neck joint with solid-state sintering of photocatalytic particles, the growth of photocatalytic particles to a size of 0.04 Eun is not suffi-cient, but the growth of photocatalytic particles to a size of 0.1 dun is necessary. When photocatalytic particles are grown to a size: of 0.1 u.m, however, the deodorizing capabil-ity becomes dependent on the film thickness, and increases as the film thickness increases. Specifically, when the film thickness was 0.5 N,m, the deodorizing capability R3o(L) exceeded 50 %, and when the film thickness was 0.8 N.m, the deodorizing capability R3o(L) reached 80 % or more. It can be seen from th.e above results that the strength of the thin photocatalytic film can sufficiently be increased when necks are produced beaween photocatalytic particles by solid-state sintering and the photocatalytic particles are grown until their crystal diameter reaches 0.1 ~.un or greater. Since the effective volume for reaction per unit volume is reduced when the crystal diameter increases to 0.1 Eun or greater, the film thickness should be of 0.5 ~m or greater, or pref-erably 0.6 Eun or greater.
(Inventive Example 29) A co_Lloidal suspension in ammonia of Ti02 sol hav-ing a crystal diameter of 0.01 ~tm was coated on a square tile base with each side 15 cm long by spray coating and 215'322 then fired at 750°C, forming a thin photocatalytic film. At this time, the 'thin Ti02 film had a porosity of 45 %, and the Ti02 particles read a crystal diameter of 0.02 elm. Sn02 sols having different crystal diameters were coated on thin pho-tocatalytic films, and dried at 110°C, producing specimens.
The produced specimens were evaluated for deodorizing and wear-resistant ~~apabilities.
The deodorizing and wear-resistant capabilities are shown in FIG. 38. The deodorizing capability remained substantially unchanged and hence was good when the crystal diameter of the Sn02 sol varied from 0.0035 dun to 0.01 ~.un.
The wear-resist~~nt capability differed depending on the crystal diamete:r of the Sn02 sol when 30 weight % or more of Snot sol was added. Specifically, when Sn02 particles having a crystal diameter of 0.008 ~.lm or less were added, the wear-resistant capability increased from a value of O to a value of O, and when Sn02 particles having a crystal diameter of 0.01 ~tm were added, they had no effect on the wear-resistant capability.
It can be understood from the above results that the wear-resistant capability increases when particles hav-ing a crystal diameter of 0.01 N.m, preferably of 0.008 ~tm or less are introduced between photocatalytic particles.
(Inventive Example 30) A colloidal suspension in ammonia of Ti02 sol hav-ing a crystal diameter of 0.01 um was coated on a square tile base with Each side 15 cm long by spray coating and 215~8?2 then fired at 850°C, forming a thin photocatalytic film.
Then, an aqueous solution of copper acetate was coated on the thin photocatalytic film by spray coating, and thereaf-ter photoreduced by a light source comprising a 20W BLB lamp for 10 seconds, thus producing specimens. The light source was spaced from the specimens by a distance of 10 cm. The carried amount of copper was 2 ~tg/cm2, and the diameters of particles of copper ranged from several to 10 nm. The crys-tal diameter of photocatalytic particles was 0.1 um. The produced specimens were evaluated for deodorizing and wear-resistant capabilities.
The deodorizing capability R3o(L) was 89 %, and the wear-resistant capability had a value of O. Comparison with the graph shown in FIG. 36 indicates that the deodorizing capability R3o(L) increased from 18 % to 89 % by carrying copper.
It can be seen from the above results that a mate-rial which has both deodorizing and wear-resistant capabili-ties can be produced when a thin photocatalytic film having a porosity of 10 % or more and less than 40 %, preferably 10 % or more and 30 % or less is formed on the surface of a base.
Embodiments in which particles smaller than inter-stices in a photocatalytic layer are filled in those inter-stices will be described below. The term "interstices" used therein indicates both interstices between spaced particles and recesses in necks between particles.

A dense photocatalytic layer is better with re-spect to film ~~trength and resistance to stains. However, since the tempE~rature at which such a dense photocatalytic layer is generally high, imposing limitations on materials available for gases, the porosity of the photocatalytic layer may be 10 ~ or greater before particles are filled in interstices at a subsequent step. Because a photocatalytic film whose porosity is of 10 ~ or greater has an excellent deodorizing caF~ability, it is possible to produce a multi-functional material which has both deodorizing and wear-resistant capat~ilities by adjusting the amount of particles to f ill interstices .
Particles that are smaller than interstices and to be filled in interstices should preferably be made of an inorganic amorF~hous material, and more preferably made of an ~ oxide semiconductor such as TiOZ, Sn02, ZnO, SrTi03 , Fe2O3, Biz03 , or W03 .
The ~~articles smaller than interstices may basi-cally be sm,allE~r than the average diameter of pores that are generated. WhEan interstices are reduced and particles at-tached to the surfaces of particles having a photocatalytic function are reduced, the smoothness of the surface of the photocatalytic layer is increased, and any defects of the surface thereof= are reduced. Consequently, the particles smaller than interstices should have diameters of less than 0.01 ~tm, preferably of 0.008 Eun or smaller. If a thin Ti02 film is of an anatase structure and fixed to a base by being 21~5~?2 heated at 850°C or lower, then the diameter of the particles may be smaller than the diameter of Ti02 particles because the average diameter of pores and the diameter of Ti02 parti-cles are essentially equal to each other as observed by an electron microscope. Inasmuch as a starting material of a thin TiOZ film having a photocatalytic activity has particle diameters of 0.05 ~tm or smaller, the diameter of the parti-cles may be of 0.05 dun or s.laller.
The ~~hotocatalytic layer is made more resistant to stains if the porosity of the photocatalytic layer in which interstices are filled with particles and which has a photo-catalytic function is less than 20 %. Furthermore, the maximum width of open pores of the photocatalytic layer should preferably be of 0.04 ~.m or smaller.
The F~orosity represents the ratio of open pores, and the maximum width of open pores represents the maximum distance across an interstice between two adjacent particles of those particles which make up the surface of the base and has a photocatalytic function (an average value + 3 x a standard deviation).
If the photocatalytic layer which has a photocata-lytic function has a porosity of about 10 % before particles are filled in interstices, then the porosity will be reduced below 10 %. Since the pores to be filled are large enough to accommodate particles whose crystal diameter is of less than 0.01 qua, the pores are large compared with the size (several 1~) of the particles of a gas, and do not affect the 2I55~~2 deodorizing capability, thereby maintaining the same deodor-izing characteristics as those of a produced thin Ti02 film whose porosity is of 10 ~ or greater.
In the case where a photocatalytic layer having a photocatalytic function is composed primarily of crystalline photocatalytic particles, scums will not be deposited on the photocatalytic layer in the same manner as they are depos-ited o~~ glass, and, even if deposited, can be wiped off relatively easily. If the photocatalytic layer is used in water, algae will not easily be grown on the photocatalytic layer.
The crystalline photocatalytic particles are pho-tocatalytic particles which are crystallized to the extent that when the photocatalytic particles which are removed from a member are subjected to powdery X-ray diffraction under the conditions of 50 kV - 300 mA, a maximum peak of crystal (e.g., 28 = 25.3° for anatase TiOz particles and 28 =
27.4° for rutile Ti02 particles) is detected.
The particles are filled in the interstices by coating, drying', and heating a metal alkoxide, an organic metallic salt, a sulfate, or the like. For example, if a metal alkoxide is used, a solution of a mixture containing a metal alkoxide, a diluent, and hydrochloric acid is dried on the outermost surface of a photocatalytic layer, and there-after dried with heat. The diluent preferably comprise ethanol, propanol, methanol, or the like, but is not limited to these materials. However, the diluent should contain as little water as possible. If water were contained in the diluent, the hydrolysis of the metal alkoxide would be vio-lently accelerated, causing cracks in the photocatalytic layer. The hydrochloric acid is added in order to prevent the photocatalyic layer from cracking when dried or heated.
The metal alkoxide is usually coated by flow coating, but may be coated b:y any of other coating processes. The flow coating process should preferably be carried out in dry air.
If the metal alkoxide were flow-coated in ordinary air (atmospheric air), then the hydrolysis of the metal alkoxide would be accelerated by the humidity of the air, making is difficult to control the film thickness. The metal alkoxide may be coated once or several times depending on the ability of the photocatalytic layer to be filled. When the coated photocatalytic layer is left to stand in dry air for several minutes, a film is produced in which particles are filled in interstices in the photocatalytic layer.
If the photocatalytic layer to be coated with filling particles is of the same material as the filling particles, then a film having excellent mechanical strength is produced because of the same coefficient of thermal ex-pansion.
A spE~cific example in which a Ti alkoxide is used to fill interstices will be described below. When the Ti alkoxide is coated on the surface of a photocatalytic layer and then dried with heat, the amount of Ti alkoxide coated in one coating cycle was 10 ~un/cm2 or greater and 100 ~.tm/cm2 _~ 2I55~?2 or smaller in terms of the amount of Ti. If the amount of Ti alkoxide coai~ed in one coating cycle were too small, then the process would not be efficient because the number of coating cycles would have to be increased. If the amount of Ti alkoxide coai~ed in one coating cycle were too large, the thickness of a ~~ilm produced in one coating cycle would to so large that ii. would be cracked when dried or heated.
In the drying step, the coated Ti alkoxide was heated at a tem~~erature of 400°C or higher or 800°C or lower. If the itemperature were lower than 400°C, then amor-phous Ti02 would. not be crystallized into anatase Ti02. If the temperature were higher than 800°C, then rapid grain growth would occur, resulting in a reduction in photoactiv-ity.
The amount of hydrochloric acid with respect to the Ti alkoxide in the coating solution was 1 weight % or higher or 10 weight % or lower. If the proportion of hydro-chloric acid we~_e smaller than 1 weight %, then the filled particles would not be sufficiently effective to prevent cracking. If the proportion of hydrochloric acid were greater than 10 weight %, then too much water would be in-troduced as the hydrochloric acid is normally in the form of an aqueous solui~ion of 36 % of hydrochloric acid, the hy-drolysis would he accelerated excessively, causing cracking.
If the amount o:E hydrochloric acid is large, then the dilu-ent should also be added in a large amount because the dilu-ent suppresses ~~he hydrolysis. The ratio of the hydrochlo-ric acid (exclusive of water) to the diluent should be in the range of from about 1 . 100 to 1 . 1000.
After a photocatalytic layer having a photocata-lytic function has been formed and a layer has been formed in which particles smaller than interstices produced in the surface of the photocatalytic layer are filled in those in-terstices, at least one metal of Cu, Ag, Zn, Fe, Co, Ni, Pd, and Pt may be fixed to the latter layer. Since the metal occupies sites of high adsorptivity of the photocatalytic layer, an alkaline metal, calcium, etc. in dust are pre-vented from being attached to those sites, and hence the photocatalytic layer is prevented from losing its photocata-lytic activity. Consequently, the antibacterial function produced by the photocatalyst is not impaired, and the pho-tocatalytic layer is prevented from being stained due to a deposit of bacteria. If the metal of Cu, Ag, or Zn is fixed to the layer, then since it has an antibacterial capability itself, the photocatalytic layer is prevented more effec-tively from being stained due to a deposit of bacteria. In addition, the metal has an electron-capturing effect which improves the photoactivity of the photocatalytic layer.
Particles of the metal to be fixed to the layer should be large enough to occupy sites of high adsorptivity of the photocatalytic layer and small enough to keep high activity. From. these standpoints, the particle of the metal to be fixed to the layer should preferably have a diameter ranging from several nm to 10 nm.

__ 2I5~~22 The metal may be fixed to the layer by any of various processes including photoreduction, heat treatment, sputtering, CVD, etc. Of these processes, photoreduction is most preferable because it can fix the metal firmly through a relatively simple procedure without the need for large-scale facilities. In the process of photoreduction, an aqueous solution containing ions of at least one metal of Ag, Cu, An, Fe, Co, Ni, Pd, and Pd is coated on a layer, and then irradiated with light containing ultraviolet rays. The aqueous solution containing ions of at least one metal of Ag, Cu, An, Fe, Co, Ni, Pd, and Pd may be an aqueous solu-tion of copper acetate, silver nitrate, copper carbonate, copper sulfate, cuprous chloride, cupric chloride, chloro-platinic acid, ~~alladium chloride, nickel chloride, zinc nitrate, cobalt chloride, ferrous chloride, or ferric chlo-ride. Basicall~~, the aqueous solution may be coated in any of various processes, but the spray coating or dip coating process is easy to carry out. Comparison of the spray coat-ing and dip coasting processes shows that the spray coating process is preferable to the dip coating process because it uses a smaller amount of solution, can coat the solution to a uniform film i~hickness, can easily control the film thick-ness, and can bE= performed so as not to coat the reverse side. The lights source for radiating light containing ul-traviolet rays may be any light source which is capable of radiating light containing ultraviolet rays, and may spe-cifically be an ultraviolet lamp, a BLB lamp, a xenon lamp, a mercury lamp, or a fluorescent lamp. It is preferable to position the specimen such that the light containing ultra-violet rays will perpendicularly be applied to the surface to be irradiated because the irradiation efficiency is the greatest. The light containing ultraviolet rays should preferably be applied for a period of time ranging from about 10 seconds to 10 minutes. If the period of time for which 1'ght containing ultraviolet rays is applied were too short, then the metal would not sufficiently be attached to sites of high adsorptivity of the photocatalytic layer, al-lowing an alkaline metal, calcium, etc. in dust to be at-tached to those sites, so that the photocatalytic layer would lose its photocatalytic activity. If the period of time for which light containing ultraviolet rays is applied were too long, then the metal would excessively be attached to sites of high adsorptivity of the photocatalytic layer, preventing sufficient light from reaching the photocatalytic layer, so that the photocatalytic activity would be lowered.
The specimen should preferably be spaced from the light source by a distance ranging from 1 cm to 30 cm. If the distance between the specimen and the light source were too small, then light would not be applied with uniform illumi-nance to the entire surface of the specimen, and the metal would irregularly be attached to the sites of high adsorp-tivity of the photocatalytic layer. If the distance between the specimen and the light source were too large, then since the illuminance of the applied light is in inverse propor-tion to the square of the distance, the metal would not firmly be attached to the sites of high adsorptivity of the photocatalytic layer.
Examples in which particles smaller than intersti-ces in a photoc~atalytic layer are filled in those intersti-ces will be described below.
( Inventive Exam~gle 31 ) A colloidal suspension in ammonia of Ti02 sol hav-ing a crystal diameter of 0.01 ~.un was coated on a square tile base with each side 15 cm long by spray coating and then fired at 7.50°C, forming an anatase Ti02 film. At this time, the thin '.~i02 film had a porosity of 45 %, and the Ti02 particles had a crystal diameter of 0.02 Elm. Sn02 sols hav-ing different crystal diameters were coated on thin Ti02 films, and dried at 110°C, producing specimens. The pro-duced specimens were evaluated for deodorizing and wear-resistant capabilities, and resistance against stains.
The deodorizing capability was evaluated by meas-uring R,o (L ) The wear resistance was evaluated by rubbing the specimens with a plastic eraser and comparing changes in the appearance of the specimens. Evaluation indications are given below.
O : Not varied after 40 reciprocating rubbing movements against the specimens.
O . Damage was caused and the Ti02 layer was peeled off by 10 or more and less than 40 rubbing movements __ 215~~22 against the specimens.
O . Damage was caused and the Ti02 layer was peeled off by 5 or more and less than 10 rubbing movements against the specimens.
x : Damage was caused and the TiOZ layer was peeled off by less than 5 rubbing movements or less against the specimens.
The resistance against stains was evaluated by drawing a thick line on the surface of the base with a black marking ink, drying the ink, thereafter wiping off the ink with ethanol, and checking the surface for remaining stains.
Evaluation indications are given below.
O : Traces were completely removed.
O : Slight traces remained.
D : Grayish blue traces remained.
x : Black traces remained.
The results are shown in FIGS. 39 through 46.
FIG. 39 shows the resistance to stains with re-spect to the added amount of SnOZ. The added amount of SnOZ
is expressed as the ratio of the weight of Sn02 to the sum of the weight of T:iOz and weight of SnOz. When 30 % or more of Sn02 was added, the resistance to stains was greatly in-creased. There appear to be three reasons for this. First, the addition of 30 % or more of Sn02 reduced the porosity to less than 20 % (FIG. 40). Secondly, the addition of Sn02 reduced pores which have large diameters. FIG. 41 shows the maximum width o:E open pores with respect to the added amount 2I55~22 of Sn02. A studly of FIG. 41 indicates that the maximum width of open pores had a considerably small value of 0.04 ~m when the added amouni~ of Sn02 was 30 % or greater. Thirdly, the addition of SnO~ improved the surface roughness.
FIG. 42 shows the deodorizing and wear-resistant capabilities wii~h respect to the added amount of Sn02.
The deodorizing capability remained substantially unchanged and hE~nce was good when the crystal diameter of the SnOz sol varied from 0.0035 Nm to 0.01 N.m. When the amount of SnOZ was 50 % or less, R3o had a good value of 80 %
or more. Comparison~with the relationship between the added amount of Sn02 a.nd the porosity shown in FIG. 39 indicates that when the added amount of SnOZ was 40 % or more or 50 %
or less, the porosity was less than 10 %, but the deodoriz-ing capability was good. This tendency differs from the tendency of the relationship between the porosity and the deodorizing capability (FIG. 35) in the case where particles to fill interst_~ces were not added. The reason for this is considered to bE: as follows: In this example, the porosity reduced to less than 10 %, but pores as large as 0.02 ~tm still remain as shown in FIG. 41, and the crystal diameter of particles that fill interstices is of 0.0035 Vim, which is large compared with the size (several ~) of the particles of a gas. Therefore, gas passages are not closed under the present conditions free of grain growth.
The wear-resistant capability differed with the crystal diameter of the Sn02 when the added amount of SnOZ

21~5~22 was 30 % or more. Specifically, when SnOz particles having a crystal diameter of 0.008 ~tm or less were added, the wear-resistant capability increased from a value of O to a value of O, and when Sn02 particles having a crystal diameter of 0.01 ~tm were added, they had no effect on the wear-resistant capability.
The above experiment revealed the following advan-tages:
(1) When a Ti02 film is formed on a base and par-ticles (Sn02 so7_) smaller than interstices produced in the surface of the thin film are introduced into the intersti-ces, the Ti02 f~~_lm is made resistant to stains.
(2) If the added amount of Sn02 is 30 weight % or greater with respect to the total weight of Ti02 and Sn02, then the wear resistance is increased.
(3) If the added amount of Sn02 is 50 weight % or smaller with respect to the total weight of Ti02 and Sn02, then the deodorizing capability is maintained at a good level.
(4) The TiOz film is made resistant to stains when the porosity is less than 20 % and the maximum width of open pores is of 0 . 0 4 ~tm or smaller .
(Inventive Example 32) A urinal with a strainer whose side, facing away from exposure t~~ light, was coated with an anatase TiOZ film was installed a:nd tested for actual use for two weeks.
Then, the strainer and an ordinary strainer which was not coated with an anatase Ti02 film were compared with each other. Yellow stains caused by bacteria and urinary calculi were found to be deposited on both the strainers. The yel-low stains on the ordinary strainer could not be removed when it was simply rubbed. However, when the strainer with the anatase TiO;z film formed on its side was rubbed, the yel-low stains were rendered almost invisible.
Inasmuch as no light was applied ~o the side of the strainer, it is believed that the stain resistance was achieved not by the photocatalytic effect of the anatase Ti02 film, but by the formation on the strainer surface of the crystalline anatase Ti02 film that is resistant to strong attachment of stains thereto.
(Inventive Example 33) A SiC~2-A1203-Na/RZO frit was coated on the surface of a square pottery tile with each side 15 cm long, and then a colloidal suspension in ammonia of Ti02 sol having a crys-tal diameter of 0.01 pm was coated on the surface of the frit coating by spray coating. Then, the assembly was fired at 750°C for tw~~ hours, producing three thin Ti02 films hav-ing respective film thicknesses of 0.2 ~,un, 0.4 ~.un, and 0.8 dun. At this time, the thin Ti02 film had a porosity of 45 %, and the Ti02 particles had a crystal diameter of 0.02 ~tm.
The specimens which were cooled were coated with a mixture of titanate tetraethoxide, 36 % hydrochloric acid, and etha-nol at a weight ratio of 10 : 1 : 400 by flow coating with dry air used as a carrier, and then dried. The coated ~I558?2 amount of TiOz ranged from 40 to 50 ~.g/cm2. Thereafter, the specimens were fired at 500°C for 10 minutes. The step of coating the Ti ailkoxide was repeated one to five times. The produced specimE~ns were evaluated for deodorizing, antibac-terial, wear-re~~istant, and stain-resistant capabilities.
With respect to the antibacterial capability, the specimens were tested for their antibacterial ability against escherichia coli, strain: W3110. Specifically, 0.15 ml (1 - 50000 CE'U) of the bacterial solution was dropped onto the outermost surface of the multi-functional material which had been ~;terilized with 70 % ethanol, and a glass sheet (100 x 10a~ mm) was placed in intimate contact with the outermost surface of the base, thus preparing a specimen.
After the specimen was irradiated with light from a white-light lamp with 3500 luxes for 30 minutes, the bacterial solution on the irradiated specimen was wiped with a sterile gauze, and collected in 10 ml of physiological saline. The survival rates of the bacteria were determined. Evaluation indications +++, ++, +, - are the same as those described above.
Under any of the above conditions, the deodorizing capability in tE:rms of R3o(L) was 80 % or more, and the anti-bacterial capability had a value of +++.
The resistance to stains (FIG. 44) and the wear-resistant capability (FIG. 45) depended on the number of times that the ~'i alkoxide was coated and the film thickness of the Ti02 film. The resistance to stains and the wear-~1~~$?2 resistant capability increased as the number of times that the Ti alkoxide was coated increased. As the film thickness of the Ti02 film decreased, the resistance to stains and the wear-resistant capability increased with a small number of times that the ~~i alkoxide was coated. One of the reasons for this is that= the porosity of the outermost surface of the TiOZ layer was reduced by the coating of the Ti alkoxide.
FIG. 46 shows the relationship between the porosity of the outermost surface of the TiOZ layer, the number of times that the Ti alkoxide is coated, and the film thickness of the Ti02 film. The porosity of the outermost surface of the Ti02 layer is reduced as the number of times that the Ti alkoxide is coated increases, is also reduced as the film thickness of the Ti02 film. is reduced, with the same number of times that the Ti alkoxide is coated. This relationship corre-sponds well to t:he relationship between the number of times that the Ti alkoxide is coated and the film thickness of the Ti02 film, and the resistance to stains and the wear resis-tance. Particularly, the resistance to stains of either of the specimens had a value of O when the porosity was less than 20 ~ as with Inventive Example 31.
(Inventive Example 34) A SiO;,-A1z03-Na/Rz0 frit was coated on the surface of a square pottery tile with each side 15 cm long, and then a colloidal suspension in ammonia of Ti02 sol having a crys-tal diameter of 0.01 dun was coated on the surface of the frit coating by spray coating. Then, the assembly was fired 215~~22 at 750°C for two hours. At this time, the thin TiOz film had a film thickness of 0.4 E.tm and a porosity of 45 %, and the Ti02 particles had a crystal diameter of 0.02 ~.tm. The speci-men which was cc>oled was coated with a mixture of titanate tetraethoxide, ?06 % hydrochloric acid, and ethanol at a weight ratio of 10 . 1 . 400 by flow coating with dry air used as a carris~r, and then dried. The coated amount of Ti02 ranged from 40 t:o 50 ~.g/cmz . Thereafter, the specimen was fired at 500°C for 10 minutes. The step of coating the Ti alkoxide was recreated three times. Subsequently, an aqueous solution of 1 weight % of silver nitrate was coated on the specimen, and photoreduced by a light source comprising a 20W BLB lamp for 30 seconds, thus producing a specimen. The light source was spaced from the specimen by a distance of cm. The amount of silver carried on the surface of the specimen was 0.T ~g/cm2, and the particles of silver had an average diameter of about 40 nm. The produced specimen was evaluated for it.s antibacterial capability and an antibacte-rial capability after use over a long period of time.
For the antibacterial capability after use over a long period of time, the specimen was tested as follows:
The surface of the produced specimen was well cleaned with ethanol or the like and dried at 50°C. Then, bathtub water collected in a F~ublic bath was put in a sterile beaker, and the specimen was immersed in the bathtub water and left therein for one month. Thereafter, the specimen was removed from the bathtub water and cleaned by ethanol or the like, 2I5~~22 and then the outermost surface of the multi-functional mate-rial was sterilized by 70 ~ ethanol. Then, 0.15 ml (1 --50000 CFU) of a bacterial solution of escherichia coli, strain: W3110 w~~s put on a glass sheet (100 x 100 mm), which was placed in intimate contact with the outermost surface of the base, thus preparing a specimen. After the specimen was irradiated with light from a white-light lamp with 3500 luxes for 30 minutes, the bacterial solution on the irradi-ated specimen w<is wiped with a sterile gauze, and collected in 10 ml of physiological saline. The survival rate of the bacteria was de~~ermined as an indication for evaluation.
Evaluation indications used are the same as those in the antibacterial c<~pability test in Inventive Example 33.
For comparison, the specimens in Inventive Example 33 were also tested.
As a result, the initial antibacterial capabili-ties of the specimen in Inventive Example 34 and those in Inventive Examp:Le 33 had a value of +++. However, the anti-bacterial capabilities of the specimen in Inventive Example 34 and those in Inventive Example 33 after one month dif-fered from each other. Specifically, the antibacterial ca-pabilities of the specimens in Inventive Example 33 were reduced to a va:Lue of +, but the antibacterial capability of the specimen in Inventive Example 34 had the same value of +++ as the initial antibacterial capability thereof. This is because silvc=r occupies sites of high adsorptivity of the surface of the TiOz layer, thereby preventing dust from being attached to those sites of high adsorptivity during usage.
It can be understood from the above results that since a photocatalytic layer having a photocatalytic func-tion is formed on the surface of a base and particles smaller than interstices produced in the surface of the pho-tocatalytic layer are filled in those interstices, the amount and size of the interstices present in the surface of the photocatalytic layer are smaller than in the conven-tional thin photocatalytic film, and the surface smoothness is improved, so that the film thickness is increased while at the same time the deodorizing and antibacterial capabili-ties are maintained, and the photocatalytic layer is made resistant to attachment of high-polymer molecules, dust, bacterial, etc. which make up stain components.
Use of a material having a low melting point, such as soda glass, ~~s the material of a base will be described below. If a than photocatalytic film is formed on the sur-face of a base having a low melting point, then the base is softened alread~~ at a temperature at which the thin photo-catalytic film :is formed, and the formed thin photocatalytic film is embedded in the base, with the result that no light will reach the photocatalytic layer, which will fail to per-form photocatal~Ttic functions.
To avoid the above shortcoming, photocatalytic particles are f_~xed to a base through a layer such as an Si02 .__ 215~8?2 coat or the like which has a melting point higher than the base. Specific examples will be described below.
(Inventive Example 35) Before a titanium oxide was coated on a sheet of soda glass, the surface of the sheet of soda glass was coated with silica.
The surface of a square sheet of soda glass with each side 10 cm long was coated with silica as follows:
First, tetraethoxysilane, 36 % hydrochloric acid, pure wa-ter, and ethanol were mixed at a weight ratio of 6 . 2 . 6 .
86. Since heat was generated when they were mixed together, the mixture was left to stand for one hour. Then, the mix-ture was coated on the sheet of soda glass by flow coating.
Then, a coating solution was prepared by mixing titanate tetraethoxide and ethanol at a weight ratio of 1 9 and adding 10 weight % of 36 % hydrochloric acid with re-spect to the titanate tetraethoxide to the mixture. The amount of 36 % hydrochloric acid to be added should be in the ranging of from 1 weight % to 30 weight %, preferably from 5 weight % to 20 weight %, with respect to the titanate tetraethoxide. The addition of the appropriate amount of hydrochloric acid is effective to prevent the assembly from being cracked when it is subsequently dried and fired. If the added amount of hydrochloric acid were too small, then the assembly is not sufficiently be prevented from being cracked, and if the added amount of hydrochloric acid were too large, then since the amount of water contained in the 21~~~22 hydrochloric acid reagent would be increased, the hydrolysis of the titanate tetraethoxide would be accelerated, making it difficult to produce a uniform coating.
Then, the coating solution was coated on the sur-face of the soda glass base in dry air by flow coating. The term "dry air" used herein does not denote air which does not contain air at all, but denotes air which contain small air compared with ordinary air. If the coating solution were coated on the surface of the soda glass base in ordi-nary air, but not in dry air, then the hydrolysis of the titanate tetraethoxide would be accelerated by water in the air, and the amount of the solution coated in one coating cycle would be so large that the assembly would tend to be cracked when it is subsequently dried and fired. The accel-erated hydrolysis would make it hard to control the amount of the solution coated. To prevent cracking, the amount of titanium oxide carried in one cycle should preferably be 100 ~.g/cm2 or less. In this example, the amount of carried tita-nium oxide was 45 ~.g/cm2.
Thereafter, a film of titanium oxide was formed by drying the assembly in dry air for 1 -- 10 minutes. The ti-tanium oxide was formed in the process so far according to the following principles: A starting material is titanate tetraethoxide which is one type of titanium alkoxide. (Use of other titanium alkoxide produces the same result in prin-ciple.) The titanate tetraethoxide causes a hydrolytic reaction with water in dry air upon flow coating, generating 215~~22 a titanium hydroxide. Furthermore, when dried, a dehydrat-ing and condensing reaction occurs, producing amorphous ti-tanium oxide on the base. Particles of titanium oxide pro-duced at this time have diameters ranging from about 3 to 150 nm, and are highly pure. Therefore, the titanium oxide thus produced can be sintered at a temperature lower than titanium oxides produced by other manufacturing processes.
The composite material thus produced by the above process is fired at a temperature ranging from 300°C to 500°C, producing a multi-functional material. If necessary, the steps from the coating of titanate tetraethoxide to the firing of the composite material is repeated to obtain a thick coating of titanium oxide.
Specimens produced according to the above process were evaluated for deodorizing, wear-resistant, and antibac-terial capabilities. The results of the evaluation are given in Table 19 below.
(Table 19) Firing Wear re- R3o (L R3o ( Anti- Anti-) D ) temp (C) sistance bacterial bacterial ability ability (L) (D) 300 O 0 % 0 % - -400 O 60 % 0 % + -500 O 60 % 3 % + -The deodorizing capability was evaluated by plac-ing a specimen in a cylindrical container having a diameter of 26 cm and a height of 21 cm and in which an initial con-centration of methyl mercaptan was adjusted to 2 ppm, and measuring a rate (R3o(L)) at which the methyl mercaptan was removed 30 minutes after being irradiated by a 4W BLB fluo-rescent lamp 8 cm spaced from the specimen and a rate (R3o(D)) at which the methyl mercaptan was removed 30 minutes after being shielded from light.
The wear resistance was evaluated by rubbing the specimen with a plastic eraser, and comparing any change in the appearance thereof. Evaluation indications O, O, D, x used were the same as those described above.
The antibacterial capability was tested using es-cherichia coli, strain: W3110. Specifically, 0.15 ml (1 -50000 CFU) of the bacterial solution was dropped onto the outermost surface of the multi-functional material which had been sterilized with 70 % ethanol, and a glass sheet (100 x 100 mm) was placed in intimate contact with the outermost surface of the base, thus preparing a specimen. After the specimen was irradiated with light from a white-light lamp with 5200 lures for 30 minutes, the bacterial solution on the irradiated specimen and the bacterial solution on a specimen kept under a shielded condition were wiped with a sterile gauze, and collected in 10 ml of physiological sa-line. The survival rates of the bacteria were determined as indications for evaluation. Evaluation indications +++, ++, + 1 used were the same as those described above.

2155~?2 At a firing temperature of 300°C, the rubbing test indicated a good result of O, but R3o(L) was 0 %. This is considered to be because the amorphous titanium oxide was not crystallized into an anatase structure.
At a firing temperature of 400°C at which an ana-tase structure can be confirmed by x-rays in a synthesis test, the rubbing test indicated a good result of O, R3o(L) increased to 0 %, and the antibacterial capability had a value of +. At a firing temperature of 500°C, the rubbing test indicated a good result of O, and R3o(L) increased to 60 %.
When the temperature increased, the base of soda glass was deformed at 550°C, and no multi-functional mate-rial was manufactured.
(Inventive Example 36) In order to improve the photocatalytic character-istics of the specimens obtained in Inventive Example 35, metal particles were carried. The photocatalyst carries out an oxidizing reaction and a reducing reaction at the same time. If the reducing reaction were not in progress, no electrons would be consumed, and particles would be charged, and the oxidizing reaction would not be in progress either.
This appears to be responsible for the fact that R3o(L) stopped at 60 % in Inventive Example 35. To avoid this, metal particles may be carried on particles of titanium ox-ide to release electrons for thereby preventing the parti-cles from being charged.

215~~?2 Metal particles were carried by the following process: A solution of metallic salt was coated on a photo-catalyst by flow coating, and irradiated for one minute by a 20W BLB fluorescent lamp at a distance of 20 cm. The solu-tion of metallic salt comprised an ethanol solution of 1 wt % of copper acetate if copper was to be carried, and a mix-ture of water and ethanol containing 1 wt % of copper ace-tate at 1 : 1 if silver was to be carried. After being ir-radiated, the assembly was cleaned and dried. The solution containing ethanol was used rather than an aqueous solution of metallic salt because the solution of metallic salt has good wettability with respect to the specimen.
The specimen thus produced was evaluated for de-odorizing, wear-resistant, and antibacterial capabilities.
The results of the evaluation are given in Table 20. Only the specimen fired at 500°C was used for evaluation.
(Table 20) Firing Wear re- R3o (L R3o ( Anti- Anti-) D ) temp (C) sistance bacterial bacterial ability ability (L) (D) 500 O 98 % 98 % +++ +++

The rubbing test indicated a good result of O, R3a(L) greatly increased to 98 %, and the antibacterial capa-bility had a value of +++.
(Comparative Example 37) The same specimens as those of Inventive Example 35 except that no silica coating was applied were used.
Specifically, a titanium oxide was coated on a square sheet of soda glass with each side 10 cm long. The evaluated re-sults of deodorizing, wear-resistant, and antibacterial ca-pabilities of the specimens are given in Table 21.
(Table 21) Firing Wear re- R3o ( L R3o ( D Anti- Anti-) ) temp (C) sistance bacterialbacterial ability ability (L) (D) 300 O 0 % 0 % - -400 O 0 % 0 % - -500 O 0 % 0 % - -It can be seen from Table 21 that the rubbing test indicated a good result of O at the temperatures of 300°C, 400°C, 500°C, but R3o(L) was 0 % even when the process from the coating of titanate tetraethoxide to the firing of the assembly was repeated 10 times. The antibacterial capabil-ity of each specimen had a value of -.
R3°(L) was poor at 300°C because the amorphous ti-tanium oxide was not crystallized into an anatase structure.
At 400°C and 500°C, the amorphous titanium oxide was already crystallized into an anatase structure, and the poor value of R~(L) cannot be explained by the amorphous titanium oxide, but appears to be caused by the fact that 21558?2 since the base of soda glass was softened, the film of tita-nium oxide was embedded therein.
Consequently, it is possible to manufacture a multi-functional material which has deodorizing and antibac-terial capabilities, of a base having a relatively low melt-ing point by placing a layer of a high melting point between the base and a photocatalytic layer.
Embodiments which are suitable for applying a pho-tocatalytic effect to the surface of a base of plastic that is poor in heat resistance will be described below.
A base may principally be made of plastic that is poor in heat resistance, pottery, ceramic, metal, glass, a composite material thereof, or the like.
The base may be of any of various shapes, e.g., a simple shape such as a spherical shape, a solid cylindrical shape, a hollow cylindrical shape, or a planar shape such as of a tile, a wall member, a floor member, or the like, or a complex shape such as of a sanitary ware, a basin, a sink, a closet bowl seat, or the like. The surface of the base may be porous or dense.
The binder may be of a thermoplastic material such as inorganic glass, thermoplastic resin, solder, or the like, or a thermosetting material such as fluoroplastic, siloxane resin, silicon resin, or the like. However, the binder should preferably be made of a material that is re-sistant to photodegradation because it will subsequently be irradiated with light containing ultraviolet rays. Since the material according to the present invention is highly effective particularly when it can be heated only at 300°C
or lower, the thermoplastic material should preferably be able to be softened at 300°C or lower, and the thermosetting material should preferably be able to be set at 300°C or lower. Materials which can meet the above requirements are thermoplastic materials including boric acid glass, solder, and acrylic resin, and thermosetting materials including fluoroplastic, siloxane resin, and silicon resin.
The binder layer may be coated on the base by spray coating, roll coating, dip coating, or the like if the binder layer is made of a thermoplastic material. Any of these processes or other processes may be employed. The binder components may not necessarily be in conformity with the binder composition at the time the material according to the present invention is completed. For example, if the binder is made of inorganic glass, it may be coated with a suspension of inorganic glass in a frit, mass, or powdery phase, or a mixed solution of a salt containing a ~tal com-ponent which is a constituent of the final material. If the binder is made of a resin, it may be coated with a solution of the resin or other materials.
Before photocatalytic particles are coated on a binder layer, the coated binder layer may be dried to evapo-rate water or the like. To dry the coated binder layer, it may be left to stand at room temperature, or the binder layer and the base may be heated together.

._ 21~~~22 Before photocatalytic particles are coated on a binder layer, the coated binder layer may be heated at a temperature which is lower than the softening temperature of the base and at which the binder layer changes to a binder composition at the time the final material is completed and also at which the binder layer is softened. With this proc-ess, since the binder layer has been smoothened when photo-catalytic particles are to be coated on a binder layer, suf-ficient effects can be achieved even if photocatalytic par-ticles are coated in a small amount.
If the binder is made of a thermosetting material, then a diluent and thereafter a hardener may be added to the thermosetting material, and the mixture may be coated on the surface of the base.
The viscosity of the binder should be increased to a value of 105 poise or more and less than 1075 poise. With the viscosity of the binder increased to a value of 105 poise or more, coated photocatalytic particles are embedded such that they are not fully embedded in the binder layer.
With the viscosity of the binder increased to a value of less than 1075 poise, at least a lowermost layer of the pho-tocatalytic layer is partly embedded in a lower layer of the binder.
The photocatalytic particles are coated on the surface of the binder layer basically by coating a starting material that has suitably been processed on the binder layer.

The starting material should preferably be a sus-pension of a sol. of a photocatalytic material or a suspen-sion of fine particles of a photocatalytic material. At any rate, it is necessary that a surface-treating agent such as a dispersant or the like be added not to coagulate the pho-tocatalytic material in the suspension. The photocatalytic particles may be coated on the binder layer by spray coat-ing, roll coating, dip coating, or the like. Any of these processes or other processes may be employed.
The photocatalytic layer should preferably be em-bedded in the binder layer to a depth which is 1/4 or more of the thickness of the photocatalytic layer from the stand-point of the strength with which the photocatalytic layer is joined to the base. The thickness of the photocatalytic layer is determined by conducting an elementary analysis with EBMA of components of photocatalytic particles along a section of the photocatalytic layer, and covers an upper layer where the amounts of elements of the components of the photocatalytic layer are substantially constant and an em-bedded region between a depth at which the amounts of ele-ments of the components of the photocatalytic layer begin to decrease and a depth at which the amounts of elements of the components of the binder layer begin to be constant.
The surface-treating agent applied to the photo-catalyst is primarily made of a component added to disperse the sol of the starting material of the photocatalytic par-ticles. Specifically, the surface-treating agent may be made of pentaerythritol, trimethylolpropane, triethanolamine trimethylolamine, silicon resin, alkylchlorosilane, or the like.
A light source of light having a wavelength of 390 nm or shorter and an illuminance of 1.7 mw/cm2 may comprise a BLB fluorescent lamp, an ultraviolet lamp, a bactericidal lamp, a xenon lamp, or a mercury lamp. The reason why the light has to have a wavelength of 390 nm or shorter and an illuminance of 1.7 mw/cm2 is that since the dispersant such as of silicon resin has certain resistance to photodegrada-tion, the dispersant would not be decomposed unless the ul-traviolet rays had the above intensity. The shorter the ultraviolet rays, the faster the dispersant is decomposed.
However, because the binder may possibly be decomposed de-pending on its type and the ultraviolet rays are harmful to human bodies, the wavelength of the ultraviolet rays should be of 250 nm or greater. The illuminance of 3 mw/cmz or less is sufficient because the rate of decomposition increases as the illuminance increases to about 3 mw/cm2, but any further increase in the illuminance would not contribute much to an increase in the rate of decomposition.
The above process is schematically shown in FIG.
47. A photocatalytic layer 2 is disposed on a base 1 through a binder layer 6 with a lower layer of the photo-catalytic layer 2 being partly embedded in the binder layer 6. A layer 6 is composed of a surface-treating agent for obstructing a photocatalytic activity. Light W contains light having a wavelength of 390 nm or shorter and an illu-minance of 1.7 mw/cm2.
A process of forming a layer composed mainly of photocatalytic particles 3 and a thermosetting resin 6 on the surface of a base 1 and irradiating the assembly with ultraviolet rays to expose a photocatalytic layer will be described below with reference to FIG. 48. According to this process, the photocatalytic particles 3 are firmly fixed to the base 1, and when the assembly is irradiated with light having a wavelength of 390 nm or shorter and an illuminance of 1.7 mw/cm2, the irradiated portions of the surfaces of the photocatalytic particles are subjected to a photocatalytic reaction to decompose and vaporize the sur-face-treating agent and the thermosetting resin preferen-tially in a direction toward the light source. Since the photocatalytic particles are exposed to the ambient air, they can provide a sufficient photocatalytic activity.
The layer composed mainly of photocatalytic parti-cles and a thermosetting resin is formed by adding a thermo-setting resin, a diluent, and a hardener, in the order named, to a well dispersed suspension of a photocatalytic sol, coating the mixture to the surface of a base, and heat-ing the assembly.
The photocatalytic sol in the suspension should have a crystal diameter of 0.05 ~tm or smaller, more prefera-bly 0.01 ~tm or smaller because the photocatalytic activity is higher as the crystal diameter is smaller. The photo-21~~~22 catalytic sol in the suspension should also be as monodis-perse as possible because the photocatalytic particles can be coated more uniformly as the photocatalytic sol is dis-persed better.
The thermosetting resin should preferably be re-sistant to photodegradation caused by white light and ordi-nary fluorescent lamp light because it is highly durable in use. The thermosetting resin should preferably be siloxane resin or fluoroplastic.
The diluent is added in order to lower the viscos-ity of the mixture of a photocatalytic sol and a thermoset-ting resin for thereby facilitating the coating of the mix-ture on the surface of the base. Basically, the diluent may be of any material insofar as it can serve the above pur-pose. For example, the diluent may comprise water, ethanol, propanol, or the like.
The mixture may be coated on the base by spray coating, roll coating, dip coating, spin coating, or the like. Any of these processes or other processes may be em-ployed.
The heat treatment may generally be carried out by, but not limited to, an electric furnace, a gas-fired kiln, a vacuum furnace, a pressure furnace, or the like.
The layer composed mainly of photocatalytic parti-cles and a thermosetting resin may be formed on the surface of the base with a thermosetting resin layer or photosetting resin layer (intermediate layer: C) interposed therebetween, as shown in FIG. 49.
With this arrangement, the photocatalytic layer can be uniformly formed with ease because the thermosetting resin layer or photosetting resin layer disposed intermedi-ate between the base and the photocatalytic layer produces a smooth surface before the photocatalytic layer is formed even if the base has surface irregularities. Furthermore, inasmuch as the thermosetting resin layer or photosetting resin layer disposed intermediate between the base and the photocatalytic layer allows the photocatalytic layer to be joined sufficiently to the base, the layer composed mainly of the photocatalytic particles and the thermosetting resin can be thinned and the photocatalytic particles can be con-centrated in the vicinity of the surface of the base even if the base has surface irregularities. Therefore, the subse-quent step of irradiating the assembly with light having a wavelength of 390 nm or shorter and an illuminance of 1.7 mw/cmZ can be carried out in a shorter period of time. Since the layer composed mainly of the photocatalytic particles and the thermosetting resin is present on the upper surface, ultraviolet rays having a sufficient intensity to decompose and vaporize the layer in a subsequent step and usage do not reach the intermediate thermosetting resin layer or photo-setting resin layer, the thermosetting resin of this layer may be selected as desired, e.g., may be inexpensive epoxy resin to reduce the cost of the material. Alternatively, 2I5~~22 the thermosetting resin may comprise a colored resin for a better design.
The thermosetting resin layer disposed intermedi-ate between the base and the photocatalytic layer is formed, for example, by adding a diluent and then a hardener the thermosetting material, coating the mixture on the surface of the base, and solidifying the coated mixture by heating or leaving it to stand. If the layer disposed intermediate between the base and the photocatalytic layer is a photoset-ting resin layer, then the coated mixture is irradiated with light containing ultraviolet rays, rather than being heated.
The diluent is added in order to lower the viscosity of the mixture for thereby facilitating the coating of the mixture on the surface of the base. Basically, the diluent may be of any material insofar as it can serve the above purpose.
For example, the diluent may comprise water, ethanol, propanol, or the like.
Then, as shown in FIGS. 50(a) and 50(b), intersti-ces in the photocatalytic layer thus exposed on the surface of the base according to the above process are preferably filled with particles (interstitial particles : 4) smaller than the interstices for increased wear resistance.
The size of the particles smaller than the inter-stices may basically be smaller than the average of pore diameters of surface irregularities that are produced. The particles smaller than the interstices should be added in an amount large enough to cause open pores on the surface to 215~~22 have a porosity of less than 20 % because it will make the surface resistant to stains.
Specific examples will be described below.
(Inventive Example 38) The surface of a square alumina base each side 10 cm long was coated with a mixture prepared by successively adding 10 weight % of siloxane resin, a diluent, and a hard-ener, ir. the order named, to a titanium oxide sol (dispersed by an amine-base disperant) having an average particle di-ameter of 0.01 ~tm, and then fired at 150°C into comparative specimens. These specimens were irradiated by various light sources for a predetermined period of time, producing re-spective specimens. The specimens were then evaluated for a deodorizing capability R3o(L) upon irradiation.
To evaluate each specimen, the specimen was placed in a glass container of 11 liters at a distance of 8 cm from a light source (4W BLB fluorescent lamp), and a methyl mer-captan gas was introduced into the glass container until it reaches a concentration of 3 ppm in the glass container.
The deodorizing capability R3o(L) upon irradiation represents a rate of change of the concentration of the methyl mercap-tan gas 30 minutes after being irradiated.
The results of the evaluation are given in Table 22 below.
(Table 22) Light source Ultraviolet Irradiated R3o(L) (%) intensity time (day) 21~~~22 (W/cmz) None - - 30 BLB 0.3 7 32 BLB 1.69 5 52 Ultraviolet 2.0 3 74 lamp Ultraviolet 3.0 1 82 lamp When the ultraviolet intensity was 1.69 mW/cm2 or higher, the deodorizing capability had a good value in ex-cess of 50 %, and when the ultraviolet intensity was 2 mW/cm2 or higher, the deodorizing capability had a good value in excess of 70 %. The deodorizing capability had a good value when the ultraviolet intensity was 1.69 mW/cmz or higher be-cause the irradiated portions of the surfaces of the photo-catalytic particles are subjected to a photocatalytic reac-tion to decompose and vaporize the surface-treating agent and the thermosetting resin preferentially in a direction toward the light source, with the result that the photocata-lytic particles are exposed to the ambient air.
(Inventive Example 39) The surface of a square alumina base each side 10 cm long was coated with a solution of a siloxane to which a diluent and a hardener were added. After the coated alumina base was dried at room temperature for about 6 hours, it was coated with a mixture prepared by successively adding 10 weight % of siloxane resin, a diluent, and a hardener, in 215~~~2 the order named, to a titanium oxide sol (dispersed by an amine-base disperant) having an average particle diameter of 0.01 Win, and then fired at 150°C into comparative specimens.
These specimens were irradiated by various light sources for a predetermined period of time, producing respective speci-mens. The specimens were then evaluated for a deodorizing capability R,o(L) upon irradiation.
The results of the evaluation are given in Table 23 below.
(Table 23) Light source Ultraviolet Irradiated R3o(L) (%) intensity time (day) ( W/cmZ ) None - - 30 BLB 0.3 7 38 BLB 1.69 5 61 Ultraviolet 2.0 3 82 lamp Ultraviolet 3.0 1 84 lamp When the ultraviolet intensity was 1.69 mW/cm2 or higher, the deodorizing capability had a good value in ex-cess of 60 %, and when the ultraviolet intensity was 2 mW/cm2 or higher, the deodorizing capability had a good value in excess of 80 %. The deodorizing capability had a good value when the ultraviolet intensity was 1.69 mW/cmz or higher be-cause the irradiated portions of the surfaces of the photo-BLB 0.3 7 .~ 2155822 catalytic particles are subjected to a photocatalytic reac-tion to decompose and vaporize the surface-treating agent preferentially on the irradiated portions of the surfaces of the photocatalytic particles which were not decomposed and vaporized by heat treatment, with the result that the photo-catalytic particles are exposed to the ambient air.
(Inventive Example 40) The surface of a square alumina base each side 10 cm long was coated with a solution of a siloxane to which a diluent and a hardener were added. After the coated alumina base was dried at room temperature for about 6 hours, it was coated with a mixture prepared by successively adding 10 weight % of siloxane resin, a diluent, and a hardener, in the order named, to a sol of titanium oxide (dispersed by an amine-base disperant) having an average particle diameter of 0.01 Vim, and then fired at 150°C. At this stage, intersti-ces between the particles on the surface had a size in the range of from 0.1 to 0.2 arm on the average. Thereafter, the assembly was irradiated with light having an ultraviolet intensity of 2 mW/cmz from an ultraviolet lamp for three days. After it was confirmed that R3o(L) exceeded 80 %, 70 weight % of a sol of tin oxide having an average particle diameter of 0.0035 ~.m was coated on the surface, and dried at 110°C into a specimen. R3o(L) of the specimen had a good value of 81 %. The specimen was subjected to a rubbing test with a plastic eraser. In the rubbing test, a specimen with no tin oxide added was damaged and the titanium oxide was .~ 215~~22 peeled off in less than 5 rubbing movements against the specimen, and the specimen with tin oxide added remained unchanged in 10 or more rubbing movements against the speci-men. It was therefore confirmed that the wear resistance can be increased by filling interstices in the surface with particles smaller than the interstices.
Consequently, it can be seen that there can be produced a material having a good photocatalytic activity even if the material has a photocatalytic layer processed at a low temperature lower than 300°C.
A process of producing a multi-functional material having a sufficient photocatalytic activity by firing it at a low temperature lower than 300°C, with a means different from, but for the same purpose as, exposure to ultraviolet rays, will be described below.
According to this process, before a dispersant and a surface-treating agent such as a surface-active agent or the like are added to a sol of titanium oxide prepared by the hydrothermal method or the sulfuric acid method, fine metal particles are fixed to the surface of the sol of tita-nium oxide.
The fine metal particles are those metal particles which, if carried by titanium oxide, are capable of captur-ing electrons when light is applied to the titanium oxide and electrons and holes are generated. Specifically, the fine metal particles are fine metal particles of Ag, Cu, Pt, Pd, Ni, Fe, Co, or the like.

Photoreduction is a simple method of fixing the fine metal particles to the surface of the sol of titanium oxide. The sol of titanium oxide should preferably, but not necessarily, be prepared by the hydrothermal method or the sulfuric acid method. The sulfuric acid method is a method by which titanium oxide is synthesized according to the fol-lowing process:
First, ilumenite is reacted with sslfuric acid to convert Ti and Fe into a water-soluble sulfate, which is extracted with water to prepare a sulfate solution mainly composed of Ti and Fe. Then, an insoluble suspended mate-rial such as of Si02 or the like is removed from the sulfate solution. Thereafter, the sulfate solution is cooled to 10°C to 15°C, separating out iron sulfate, and then titanyl sulfate in the solution is hydrolyzed to generate titanium hydroxide. The generated titanium hydroxide is crystallized into a sol of titanium oxide by the hydrothermal process at a high temperature under a high pressure in water (generally under a saturated vapor pressure at a temperature of 110°C
or higher and lower than 200°C) with a pressure device such as an autoclave or the like.
The hydrothermal process is a process of hydrolyz-ing a titanium source such as titanium tetrachloride, tita-nium sulfate, or the like into a sol of titanium oxide at a high temperature under a high pressure in water (generally under a saturated vapor pressure at a temperature of 110°C
or higher and lower than 200°C) with a pressure device such 2I~~~22 as an autoclave or the like. A specific process of fixing fine metal particles to the surface of the sol of titanium oxide by way of photoreduction will be described below.
First, the suspension of a sol of titanium oxide prepared by the hydrothermal method or the sulfuric acid method is rendered acid or alkaline because the titanium oxide has an isoelectric point of pH 6.5 and can easily be coagulated. It is preferable to use ammonia to make the suspension alkaline because an alkaline metal such as Na, R, or the like can easily be attached firmly to titanium oxide, and if such an alkaline metal occupies active sites of tita-nium oxide at first, then it prevents Ag, Cu, Pt, Pd, Ni, Fe, Co, or the like from being attached to those active sites of titanium oxide.
Then, a solution of metallic salt having substan-tially the same pH as the suspension of the sol of titanium oxide is mixed with the suspension of the sol of titanium oxide, and the mixture is irradiated with light containing ultraviolet rays for thereby fixing the metal. If neces-sary, excessive metal is settled in the solution and then removed from the solution. The solution of metallic salt comprises a solution of a solvent and a salt including a metal which, if carried by titanium oxide, is capable of capturing electrons when light is applied to the titanium oxide and electrons and holes are generated. Specifically, the solution of metallic salt comprises a solution of a sol-vent and a salt including Ag, Cu, Pt, Pd, Ni, Fe, Co, or the 21~5~~2 like. The salt including Ag, Cu, Pt, Pd, Ni, Fe, Co, or the like may be silver nitrate, copper acetate, copper carbon-ate, copper sulfate, cuprous chloride, cupric chloride, chloroplatinic acid, palladium chloride, nickel chloride, cobalt chloride, ferrous chloride, or ferric chloride. The solvent may be water, ethanol, propanol, or the like, but should be of the same type as the suspension of the sol of titanium oxide. To the solvent, there is added, if neces-sary, a pH adjuster which may be of nitric acid, sulfuric acid, hydrochloric acid, or the like for making the solvent acid, or ammonia for making the solvent alkaline.
The mixture should be irradiated with light con-taining ultraviolet rays under the following conditions:
The light source may be anything which can apply light con-taining ultraviolet rays, and may specifically be an ultra-violet lamp, a BLB lamp, a xenon lamp, a mercury lamp, or a fluorescent lamp. The light containing ultraviolet rays may basically be applied in any way, but should be applied from above the container because ultraviolet rays will not be absorbed by the container. The distance between the light source and the container should be in the range of from sev-eral cm to several tens cm. If the container were too close to the light source, the upper surface of the specimen solu-tion would be dried by the heat emitted by the light source, and if the container were too far away from the light source, the illuminance would be lowered. The time for which the light containing ultraviolet rays is applied de-.... 215~8~2 pends on the illuminance of the light source. However, the metal is firmly attached to the photocatalytic particles when light containing ultraviolet rays is applied for a pe-riod of time ranging from several seconds to several tens minutes.
Thereafter, a thin film produced by coating and heating the sol of titanium oxide which carries the metal is formed on the surface of a base, thereby producing a multi-functional material having photocatalytic functions.
The sol of titanium oxide is usually, but not nec-essarily, heated by sintering in the atmosphere using an electric furnace, a gas-fired kiln, or the like, or accord-ing to the hydrothermal process using an autoclave or the like.
Particles of titanium oxide in the film of tita-nium oxide should preferably be of an average diameter of 1 ~m or less. If the average diameter were greater than 1 Eun, then the specific surface area would be reduced, lowering the catalytic activity.
A material having a photocatalytic action is pro-duced by forming a thin film, which is prepared by coating and heating a sol, on the surface of a base through a binder. With the binder interposed between the thin film and the binder, the intimate adhesion between the thin film and the base is improved.
A process of producing such a material having a photocatalytic action differs depending on whether the . _ 215822 binder comprises a thermoplastic binder or a thermosetting binder. Embodiments of respective processes will be de-scribed below. However, insofar as the above arrangement is satisfied, the material having a photocatalytic action may be produced by any of other processes. The thermoplastic binder may comprise a thermoplastic binder such as acrylic resin, inorganic. glass such as glaze, or solder. The ther-mosetting binder may comprise fluoroplastic, epoxy resin, siloxane resin, or the like.
If a thermoplastic binder is employed, then the material having a photocatalytic action is produced as fol-lows: First, a thermoplastic binder is coated on the sur-face of a base. Then, a sol of titanium oxide carrying metal particles is coated on the thermoplastic binder, and heated at a temperature lower than the heat-resistant tem-perature of the base, but higher than the softening point of the thermoplastic binder. When the sol of titanium oxide is thus heated, a lower layer of the titanium oxide layer which carries metal particles is partly embedded in the binder layer, thereby firming joining the base and the thin film of titanium oxide which carries metal particles.
If a thermosetting binder is employed, then the material having a photocatalytic action is produced as fol-lows: First, a mixture prepared by successively adding a diluent and a hardener to the thermosetting binder is coated on a base, and set by heat or the like. Then, a mixture prepared by successively adding a thermosetting resin, a __ 21~~~?2 diluent, and a hardener to a sol of titanium oxide carrying metal particles is coated on the set mixture on the base, and set by heat or the like.
A photosetting resin may be used instead of the thermosetting resin.
Before a dispersant and a surface-treating agent such as a surface-active agent or the like are added to a sol of titanium oxide prepared by the hydrothelmal method or the sulfuric acid method, metal particles such as of Ag, Cu, Pt, Pd, Ni, Fe, Co, or the like are fixed to the surface of the Ti02 sol, thereby covering active sites of the sol of titanium oxide with the metal particles such as of Ag, Cu, Pt, Pd, Ni, Fe, Co, or the like. Therefore, when a disper-sant and a surface-treating agent such as a surface-active agent or the like are added, they are prevented from being adsorbed to the active sites of the sol of titanium oxide, thus preventing the sol of titanium oxide from losing its activity. Consequently, the dispersant and the surface-treating agent such as a surface-active agent or the like are effective to stably disperse the photocatalytic sol, forming a uniform film on the surface of the base. At the same time, even if the assembly is fired at a low tempera-ture of less than 300°C, the photocatalytic action is pre-vented from suffering a reduction which would otherwise re-sult from attachment of the dispersant and the surface-treating agent such as a surface-active agent or the like to active sites of the photocatalytic particle layer on the 2I~~~22 surface of the base. The metal particles such as of Ag, Cu, Pt, Pd, Ni, Fe, Co, or the like which occupy the active sites of the sol of titanium oxide have an electron-captur-ing effect to increase the photocatalytic activity.
Specific examples will be described below.
(Inventive Example 41) A liquid substance produced by adding water to titanium tetrachloride in a cold bath was processed at 140°C
in an autoclave according to the hydrothermal process, pro-ducing a sol of anatase titanium oxide. The produced sol of anatase titanium oxide was dispersed in nitric acid. The dispersion had a pH of 0.8. To the dispersion, there was added an aqueous solution of 3 to 5 wt % of copper sulfate whose pH had been adjusted to about 0.8 by nitric acid. The solution was irradiated with light containing ultraviolet rays from above the container for 15 minutes by a light source comprising a 4W BLB lamp which was spaced about 10 cm from the solution. A dispersant of organic acetate was added to the solution, stabilizing the sol. The sol was coated on a square tile base with each side 15 cm long and then heated into a specimen. The produced specimen was measured for a deodorizing capability R~(L) and an antibac-terial capability upon irradiation.
To evaluate the specimen, the specimen was placed in a glass container of 11 liters at a distance of 8 cm from a light source (4W BLB fluorescent lamp), and a methyl mer-captan gas was introduced into the glass container until it 215~~22 reaches a concentration of 3 ppm in the glass container.
The deodorizing capability R3o(L) upon irradiation represents a rate of change of the concentration of the methyl mercap-tan gas 30 minutes after being irradiated.
With respect to the antibacterial capability, the specimen was tested for their antibacterial ability against escherichia coli, strain: W3110. Specifically, 0.15 ml (1000~ - 50000 CFU) of the bacterial solution was dropped onto the outermost surface of the specimen which had been sterilized with 70 $ ethanol, and a glass sheet (100 x 100 mm) was placed in intimate contact with the outermost sur-face of the base, thus preparing a specimen. After the specimen was irradiated with light from a white-light lamp with 3500 luxes for 30 minutes, the bacterial solution on the irradiated specimen was wiped with a sterile gauze, and collected in 10 ml of physiological saline. The survival rates of the bacteria were determined. Evaluation indica-tions +++, ++, +, - are the same as those described above.
The deodorizing capability in terms of R3o(L) had a good value of 85 %, and the antibacterial capability had a good value of +++.
(Comparative Example 42) A liquid substance produced by adding water to titanium tetrachloride in a cold bath was processed at 140°C
in an autoclave according to the hydrothermal process, pro-ducing a sol of anatase titanium oxide. The produced sol of anatase titanium oxide was dispersed in nitric acid. The dispersion had a pH of 0.8. To the dispersion, there was added a dispersant of organic acetate, stabilizing the sol.
The sol was coated on a square tile base with each side 15 cm long and then heated into a specimen. The produced specimen was measured for a deodorizing capability R3a(L) and an antibacterial capability upon irradiation.
The deodorizing capability in terms of R3°(L) had an insufficient value of 5 %, and the antibacterial capabil-ity had an insufficient value of -.
(Inventive Example 43) A liquid substance produced by adding water to titanium tetrachloride in a cold bath was processed at 140°C
in an autoclave according to the hydrothermal process, pro-ducing a sol of anatase titanium oxide. The produced sol of anatase titanium oxide was dispersed in nitric acid. The dispersion had a pH of 0.8. To the dispersion, there was added an aqueous solution of 3 to 5 wt % of copper sulfate whose pH had been adjusted to about 0.8 by nitric acid. The solution was irradiated with light containing ultraviolet rays from above the container for 15 minutes by a light source comprising a 4W BLB lamp which was spaced about 10 cm from the solution. A dispersant of organic acetate was added to the solution, stabilizing the sol. A mixed solu-tion prepared by successively adding a diluent of propanol and a hardener to siloxane resin was coated on the surface of a square alumina base with each side 10 cm long, and dried at 100°C. The assembly was then coated with a mixed solution prepared by successively adding 20 weight % of siloxane resin with respect to the amount of titanium oxide, propanol, and a hardener to the sol produced in the manner described above, and fired at 150°C, producing a specimen.
The produced specimen was measured for a deodorizing capa-bility R3o(L) upon irradiation.
The deodorizing capability in terms of R3o(L) had a good value of 80 %.
(Comparative Example 44) A liquid substance produced by adding water to titanium tetrachloride in a cold bath was processed at 140°C
in an autoclave according to the hydrothermal process, pro-ducing a sol of anatase titanium oxide. The produced sol of anatase titanium oxide was dispersed in nitric acid. The dispersion had a pH of 0.8. To the dispersion, there was added a dispersant of organic acetate, stabilizing the sol.
A mixed solution prepared by successively adding a diluent of propanol and a hardener to siloxane resin was coated on the surface of a square alumina base with each side 10 cm long, and dried at 100°C. The assembly was then coated with a mixed solution prepared by successively adding 20 weight %
of siloxane resin with respect to the amount of titanium oxide, propanol, and a hardener to the sol produced in the manner described above, and fired at 150°C, producing a specimen. The produced specimen was measured for a deodor-izing capability R3o(L) upon irradiation. The deodorizing 21~~~22 capability in terms of R3o(L) had an insufficient value of 22 It can be seen from the above examples that before a dispersant and a surface-treating agent such as a surface-active agent or the like are added to a sol of titanium ox-ide prepared by the hydrothermal method or the sulfuric acid method, metal particles of Ag, Cu, Pt, Pd, Ni, Fe, Co, or the like are fixed to the surface of the sol of titanium oxide, so that a material having a sufficient photocatalytic action can be formed by being fired at a low temperature of less than 300°C on a base which is not resistant to heat, e.g., a plastic base.
While the above embodiments have been described primarily with respect to anatase Ti02, embodiments with re-spect to rutile Ti02 will be described below.
FIG. 51 is a block diagram of a process of a multi-functional material composed of rutile Ti02. According to the present invention, a thin rutile Ti02 film is formed on the surface of a base such as a tile or the like by coat-ing a Ti02 sol, a Ti alkoxide, a sulfate of Ti, a chloride solution of Ti, or the like on the base and thereafter heat-ing the coated layer.
If a Ti02 sol is employed, then since Ti02 has an isoelectric point of pH 6.5 and hence is substantially neu-tral, it can easily be coated uniformly on the base in the form of an aqueous solution in which it is dispersed by an acid or alkali. If the base is of metal, then an alkaline 21~5~22 dispersion is preferable from the standpoint of erosion re-sistance. The acid may be a sulfuric acid, a hydrochloric acid, an acetic acid, a phosphoric acid, an organic acid, or the like. The alkali may be ammonia, a hydroxide including an alkaline metal, or the like, but should preferably be ammonia as it will not produce a metal contaminant after being heated. To the dispersion, there may be added a dis-persant of organic acid or phosphoric acid, a surface-treating agent, and a surface-active agent. Since smaller particle diameters allow an initial sintering phase to occur at a lower temperature, producing a thin photocatalytic film having an excellent peel strength at a low temperature, the average particle diameter of the TiOz sol should be 0.05 E.tm or smaller, and preferably 0.01 ~tm or smaller.
The Ti02 sol, the Ti alkoxide, the sulfate of Ti, the chloride solution of Ti, or the like should preferably be coated on the base by spray coating, dip coating, roll coating, or spin coating as these processes require no spe-cial equipment and can form coatings inexpensively as com-pared with CVD, electron beam evaporation, sputtering, or the like.
The heat treatment may be carried out as firing in the atmosphere using an electric furnace, a gas-fired kiln, or the like, or as a hydrothermal process using an autoclave or the like.
A solution of at least one of Cu, Ag, Fe, Co, Pt, Ni, Pd, and Cu20, i.e., an aqueous solution containing metal ions, is prepared, and coated on a thin rutile Ti02 film.
The aqueous solution of metal salt may be coated by a proc-ess which prevents the aqueous solution of metal salt from being applied to the reverse side of the base. The solvent of the aqueous solution of metal salt may be water, ethanol, or the like. If water is used as the solvent, it is effec-tive to add a sacrificial oxidizing agent of alcohol, un-saturated hydrocarbon, or the like. The solvent of ethanol is preferable because it does not produce rust on a base of metal, increases a drying rate, and is less harmful than other solvents of ether, acetone, methanol, etc.
In order to increase the carrying efficiency, the aqueous solution of metal salt is dried at a temperature ranging from room temperature to 110°C, and the metal salt is irradiated with light containing light having a wave-length of 390 nm or shorter to reduce metal ions for thereby separating out and fixing the metal to the thin rutile Ti02 film. A lamp for applying light may comprise an ultraviolet lamp, a BLB (black light blue) lamp, a xenon lamp, a mercury lamp, or a fluorescent lamp. The light should be perpen-dicularly be applied to the surface to be irradiated for increasing the irradiation efficiency.
Specific examples will be described below.
(Inventive Example 45) A dispersion in ammonia of Ti02 sol having an av-erage diameter of 0.01 ~m was coated on a square alumina base with each side 10 cm long by spray coating and then 215~~2~
fired at 900°C, forming a thin rutile TiOz film. Then, an aqueous solution of copper acetate was coated on the thin rutile Ti02 film by spray coating, and thereafter photore-duced by a light source comprising a 20W BLB lamp for 10 seconds, thus producing a specimen. The light source was spaced from the specimen by a distance of 10 cm. The speci-men was evaluated for photoactivity A(L).
The photoactivity A(L) is represented by the abso-lute value of a gradient of a linearly approximated reaction curve plotted with respect to a gas concentration indicated on the Y-axis and a reaction time indicated on the X-axis.
The concentration Xt at a time t is expressed by:
Xt = Xo ~ 1 O A~L~t ( 1 ) The photoactivity A(L) can be determined by passing a cer-tain gas to be decomposed over a thin photocatalytic film irradiated with light containing ultraviolet rays and ob-serving a reduction in the concentration of the gas upon elapse of the time t. In this experiment, methyl mercaptan, which is an odorous component, was used as a gas to be de-composed, the specimen was placed in a cylindrical container having a diameter of 26 cm and a height of 21 cm and in which an initial concentration of methyl mercaptan was ad-justed to 2 ppm, and a time-dependent change of the concen-tration of methyl mercaptan was observed when the specimen was irradiated with light from a 4W BLB fluorescent lamp which was 8 cm spaced from the specimen.

The results of the experiment are shown in FIGS.
52 and 53. Each of FIGS. 52 and 53 is a graph showing the relationship between the concentration of Cu in the solution and the photoactivity A(L). FIG. 52 illustrates the rela-tionship at the time the aqueous solution of copper acetate was photoreduced after the aqueous solution of copper ace-tate was sprayed and dried, and FIG. 53 illustrates the re-lationship at the time the aqueous solution of copper ace-tate was photoreduced after the aqueous solution of copper acetate was sprayed but not dried.
When the aqueous solution of copper acetate was photoreduced after the aqueous solution of copper acetate was sprayed but not dried, as shown in FIG. 53, the photoac-tivity A(L) was of about 3 x 10-5 and remained unchanged and saturated even if the concentration of Cu in the solution increased from 0.001 weight % to 0.1 weight When the aqueous solution of copper acetate was photoreduced after the aqueous solution of copper acetate was sprayed and dried, as shown in FIG. 52, the photoactiv-ity A(L) was of about 2 x 10-5, which is substantially the same value as when the aqueous solution of copper acetate was not dried, at the time the concentration of Cu in the solution was 0.001 weight %, but sharply increased to about 2 x 10-Z at the time the concentration of Cu in the solution increased to 0.1 weight %.
(Inventive Example 46) _. 215~~~2 A thin rutile Ti02 film was formed on a floor tile and a wall tile in the same manner as with Inventive Example 45, and Cu was fixed by photoreduction to the thin rutile Ti02 film after an aqueous solution of copper acetate was coated and dried. The relationship between the concentra-tion of the metal component in the solution and the odor removal rate R3o is shown in FIGS. 54 and 55.
It can be seen from FIGS. 54 and 55 that insofar as the concentration of the metal component in the solution is of a certain high value, an odorous component can be re-moved even if the base is a tile, by photoreducing Cu after the aqueous solution of copper acetate is dried.
(Inventive Example 47) A dispersion in ammonia of Ti02 sol having an av-erage diameter of 0.01 ~.un was coated on a square tile base with each side 15 cm long by spray coating and then fired at various temperatures, forming thin rutile TiOZ films. Then, an aqueous solution of copper acetate was coated on the thin rutile Ti02 films by spray coating, and thereafter photore-duced by a light source comprising a 20W BLB lamp for 10 seconds, thus producing specimens. The light source was spaced from the specimens by a distance of 10 cm. The specimens were evaluated for a deodorizing capability R,o~
The results of the evaluation are shown in FIG.
56. The value R3o at 900°C (the percentage of open pores: 10 was better than with a rutile structure which carries no metal. When the temperature increased to 1000°C (the per-2I55~22 centage of open pores: 3 ~), the value R3o of the specimen with no metal carried was sharply reduced, and the value R3o of the specimen with Cu added was slightly reduced. There are two reasons why the deodorizing capability was reduced at 1000°C as compared with the deodorizing capability at 900°C. According to one reason, as the percentage of open pores is reduced, the area of the thin rutile TiOz film of photocatalyst for contact with a gas to be decomposed is reduced. The deodorizing capability of the specimen with no metal carried was reduced primarily for this reason. The other reason is that as the percentage of open pores is re-duced, the area in which metal particles separated out by photoreduction can exist is also reduced because the mean free path of electrons as they move.
FIG. 57 shows the relationship between the concen-trations of Ag, Cu in the solution and the color difference.
It can be seen from FIG. 57 that the concentration of Cu is smaller than the concentration of Ag at any changes in the color difference and brightness, and any coloring is not prominent. Since Cu having a valence of 0 and Cu having a valence of 1 are detected in the system of Cu by an analysis such as ESCA (electron spectroscopy for chemical analysis), the difference in coloring appears to be caused by the Cu having a valence of 1.
(Inventive Example 48) A dispersion in ammonia of Ti02 sol having an av-erage diameter of 0.01 dun was coated on a square tile base 21~~~22 with each side 15 cm long by spray coating and then fired at various temperatures, forming thin rutile TiOz films. Then, an aqueous solution of silver nitrate was coated on the thin rutile Ti02 films by spray coating, and thereafter photore-duced by a light source comprising a 20W BLB lamp for 10 seconds, thus producing specimens. The light source was spaced from the specimens by a distance of 10 cm. The specimens were evaluated for a porosity of the thin rutile Ti02 film, a deodorizing capability R3o, and a wear resis-tance. The results of the evaluation are shown in FIG. 58.
The deodorizing capability was increased when the porosity was 10 % or higher, and the wear resistance had a value of O or better when the porosity was less than 40 %.
The wear resistance was evaluated by rubbing the specimens with a plastic eraser and comparing changes in the appearance of the specimens. Evaluation indications are indicated below.
O : Not varied after 40 reciprocating rubbing movements against the specimens.
O . Damage was caused and the titanium oxide film was peeled off by 10 or more and less than 40 rubbing movements against the specimens.
0 . Damage was caused and the titanium oxide film was peeled off by 5 or more and less than 10 rubbing movements against the specimens.
x . Damage was caused and the titanium oxide film was peeled off by less than 5 rubbing movements 21~~~22 or less against the specimens.
(Inventive Example 49) A dispersion in ammonia of Ti02 sol having an av-erage diameter of 0.01 um was coated on a square alumina base with each side 10 cm long having a glazed layer thereon by spray coating and then fired at temperatures of 850°C or higher and lower than 1000°C, forming thin rutile Ti02 films.
Then, an aqueous solution of silver nitrate was coated cn the thin rutile Ti02 films by spray coating, and thereafter photoreduced by a light source comprising a 20W BLB lamp for seconds, thus producing specimens. The light source was spaced from the specimens by a distance of 10 cm.
The specimens were evaluated for antibacterial, wear-resistant, peeling-resistant, stain-resistant, acid-resistant, and alkali-resistant capabilities, and Ag col-orability.
With respect to the antibacterial capability, the multi-functional material was tested for its antibacterial ability against escherichia coli, strain: W3110. Specifi-cally, 0.15 ml (1 - 50000 CFU) of the bacterial solution was dropped onto the outermost surface of the multi-functional material which had been sterilized with 70 % ethanol, and a glass sheet (100 x 100 mm) was placed in intimate contact with the outermost surface of the base, thus preparing a specimen. After the specimen was irradiated with light from a white-light lamp with 3500 lures for 30 minutes, the bac-terial solution on the irradiated specimen and the bacterial 215~~22 solution on a specimen kept under a shielded condition were wiped with a sterile gauze, and collected in 10 ml of physiological saline. The survival rates of the bacteria were determined as indications for evaluation. Evaluation indications +++, ++, +, - are the same as those described above.
The peeling-resistant capability test is a test conducted under conditions stricter khan those of the wear-resistant capability test, and uses a typewriter eraser (LION TYPEWRITER ERASER 502) which applies greater shearing forces, rather than a plastic eraser. Specifically, the surface of each of the specimens was rubbed 20 times under equal forces by a typewriter eraser, and its damaged or scratched condition and a standard sample were visually com-pared with each other. Evaluation indications are given below.
O . Not changed at all.
O : A slight change was confirmed depending on the in tensity of light applied to the specimen.
O : A slight change was confirmed.
x . A change was confirmed at sight.
The stain-resistant capability test is a test for checking a specimen for its resistance to staining. Spe-cifically, the surface of each of the specimens was stained with an aqueous solution of 0.5 % of methylene blue, dried and then cleaned with water, and visually observed for any stain.

21~5~22 Evaluation indications are given below.
O . Stains were completely eliminated.
O . Stains slightly remained though their color cannot be recognized.
D . The light color of stains remained.
x . The dark color of stains remained.
The acid-resistant capability was evaluated by immersing each :>f the specimens in an aqueous solution of 10 ~ of HC1 for 120 hours and visually observing the thin ru-tile Ti02 film disposed on the surface of the base and carry-ing Ag for any abnormal condition. Evaluation indications are given below.
O : Not varied.
O . Discolored very slightly.
O : Discolored slightly.
x . Discolored clearly.
The alkali-resistant capability was evaluated by immersing each of the specimens in an aqueous solution of 5 ~ of NaOH for 120 hours and visually observing the thin ru-tile Ti02 film disposed on the surface of the base and carry-ing Ag for any abnormal condition. Evaluation indications are given below.
O . Not varied.
O . Discolored very slightly.
D . Discolored slightly.
x : Discolored clearly.

21~~~22 The Ag colorability was evaluated by visually com-paring each of the specimens with a specimen with no Ag added. Evaluation indications are given below.
O . Not colored.
O : Colored very slightly.
O . Colored slightly.
x : Colored brown.
The results of the evaluation for the above seven items are given in Table 24 below. The effect which the film thickness and the firing temperature have on the anti-bacterial capability is shown in Table 25.
(Table 24) The relationship between the thickness and various charac-teristics of thin photocatalvtic films Film Anti- Wear Peeling Stain Acid Alkali Ag thick- bacte- resist-resist- resist-resist- resist-color-ness(E.~mria ance ance ance ancd ance ability (L) 0.1 +++ O O O O O (~

0.2 +++ O O O O O O

0.3 +++ O O O O O O

0.4 +++ O O O O O O

0.5 +++ O O O O O O

0.6 +++ O O O O O O

0.7 +++ O O O O O O

0.8 +++ O O O O O O

0.9 +++ O O O O O O

1.0 +++ O x ~ x ~ O ~ O ~ x ~_ 215~8~2 (Table 25) The effect which the film thickness and the firing tempera-ture have on the antibacterial capability of thin photocata-lytic films Temperature 800C 900C 920C 940C 960C 980C
Film thickness 0.1 Nm +++ ++ ++

0.2 Elm +++ ++

0.3 elm +++ +++ +++ ++

0.4 Eun +++ +++ +++

0.5 Eun +++ +++ +++ ++

0.6 Etm +++ +++ +++

0.7 Etm +++ +++ +++ +++

0.8 Etm +++ +++ +++

0.9 Eun +++ +++ +++

1.0 Elm +++

The antibacterial capability of all the specimens had a good value of +++ if the thickness of the thin photo-catalytic film was in the range of from 0.1 ).lm to 1.0 ~tm insofar as the firing temperature was appropriate. However, as shown in Table 25, as the film thickness was reduced to and below 0.2 Etm, the antibacterial capability of the speci-mens fired at a high temperature of 980°C had a slightly reduced value of ++. This is because the glazed layer was softened, permitting the thin photocatalytic film to be lo-21~~~22 cally embedded in the glazed layer. Though Ag has an anti-bacterial capability itself, the tendency of the antibacte-rial capability to depend on the firing temperature indi-cates that the antibacterial capability of the composite material produced according to the method of the present invention is related to the characteristics of the thin ru-tile Ti02 film, other than the antibacterial capability of Ag, because Ag was carried after the assembly was fired.
It is considered that the embedding of the thin photocatalytic film into the glazed layer as it is softened occurs to a certain extent in all the specimens. In this example, however, it was confirmed that the thin photocata-lytic film could be maintained on the outermost surface layer of the glazed layer if the thickness of the thin pho-tocatalytic film was of at least 0.1 N.m insofar as the fir-ing temperature was appropriate.
The wear-resistant capability of all the specimens had a good value of O if the thickness of the thin photo-catalytic film produced according to this example was in the range of from 0.1 Eun to 1.0 Eun. The wear-resistant capabil-ity is much better than that of a specimen produced with no glaze interposed, which had a value of O. This is because, with the glaze being interposed, when the assembly was fired, the glaze was softened, and the lower layer of the thin photocatalytic film is allowed to be embedded in the glazed layer.

21~~g~2 The peeling-resistant capability had a value of O
when the thickness of the thin photocatalytic film was in the range of from 0.1 ~tm to 0.4 ~tm, a value of O when the thickness of the thin photocatalytic film was in the range of from 0.4 ~tm to 0.9 ~tm, and a value of x when the thick-ness of the thin photocatalytic film was of 1.0 Etm. It was observed that the peeling-resistant capability tended to be reduced as the thickness of the thin photocatalytic film increased because the thin photocatalytic film was apt to be peeled off as the ratio of the thickness of the film portion embedded in the glaze to the film thickness increased. Some specimens which did not fail in the wear-resistant capabil-ity test failed in the peeling-resistant capability test due to different shearing forces.
The stain-resistant capability had a value of O
when the thickness of the thin photocatalytic film was in the range of from 0.1 ~tm to 0.4 ~,un, a value of O when the thickness of the thin photocatalytic film was in the range of from 0.4 Etm to 0.9 Vim, and a value of x when the thick-ness of the thin photocatalytic film was of 1.0 N.m. It was observed that the stain-resistant capability tended to be reduced as the thickness of the thin photocatalytic film increased.
The acid-resistant capability of all the specimens had a good value if the thickness of the thin photocatalytic film produced according to this example was in the range of from 0.1 ~.un to 1.0 ~tm. However, since acid-resistant capa-215~~22 bility had a value of O when the thickness of the thin pho-tocatalytic film was in the range of from 0.4 N.m to 1 Eun, and a value of O when the thickness of the thin photocata-lytic film was :in the range of from 0.1 ~m to 0.4 ~.un, the acid-resistant capability exhibited a better value as the film thickness is smaller.
The alkali-resistant capability of all the speci-mens had a good value if the thickness of the thin photo-catalytic film produced according to this example was in the range of from 0.1 ~m to 1.0 ~tm. However, since acid-resistant capability had a value of O when the thickness of the thin photocatalytic film was in the range of from 0.4 ~t.m to 1 N,m, and a value of O when the thickness of the thin photocatalytic film was in the range of from 0.1 ~tm to 0.4 Etm, the alkali-resistant capability exhibited a better value as the film thickness is smaller.
The Ag colorability had a value of O when the thickness of the thin photocatalytic film was in the range of from 0.1 Wn to 0.4 ~.m, a value of O when the thickness of the thin photocatalytic film was in the range of from 0.4 ~tm to 0.9 Etm, and a value of x when the thickness of the thin photocatalytic film was of 1.0 Eun. It was observed that the Ag colorability tended to be reduced as the thickness of the thin photocatalytic film increased. This tendency is the same as the tendency of the stain-resistant capability.
It can be seen from the above tests for the seven items that the thickness of the thin photocatalytic film ~1~~~22 should be of O.:l ~tm or greater and 0.9 dun or smaller, more preferably 0.1 ~.m or greater and 0.4 Eun or smaller. It was recognized that the wear-resistant capability increased when the thin photocatalytic film was fixed to the base through the glaze.
Design characteristics vary depending on the film thickness. Specifically, when the film thickness is of 0.2 ~tm or greater and less than 0.~ ~.tm, an iridescent striped pattern is produced due to the interference between visible light and the thin photocatalytic film, giving a special appearance impression. When the film thickness is of less than 0.2 ~.un or 0.4 Eun or greater and 0.9 dun or smaller, no iridescent striped pattern is produced, and the appearance resulting from the color of the base or the color and pat-tern of the glaze, or their combination is utilized as it is.
(Inventive Example 50) A dispersion in ammonia of TiOZ sol having an av-erage diameter of 0.01 Nm was coated on a square tile base with each side :15 cm long by spray coating and then fired at 900°C, forming a thin rutile Ti02 film having a thickness of 0.8 elm. Then, aqueous solutions of copper acetate which had respective solution concentrations of 0.2 weight %, 0.5 weight %, and 1 weight % were coated in varying amounts on the thin rutile Ti02 film by spray coating, and thereafter photoreduced by a light source comprising a 20W BLB lamp for 30 seconds, thus producing specimens. The light source was ~. 2155822 spaced from the specimens by a distance of 10 cm. The specimens were evaluated for an antibacterial capability.
The amounts of carried Cu were determined by collecting the remaining aqueous solutions after being irradiated and cal-culating the difference between the initial amounts of cop-per and the collected amounts of copper.
FIG. 59 shows the relationship between the amount of carrie.: Cu and the bacteria survival ratios upon irradia-tion (L) and non-irradiation (D). Study of FIG. 59 reveals the following:
First, the antibacterial capability increased with carried Cu. Next, the antibacterial capability increased with a smaller amount of carried Cu upon irradiation (L) than upon non-irradiation (D). This is because the thin rutile Ti02 film whose photoactivity was recovered by carried Cu performs a photocatalytic action upon irradiation (L).
It can be seen from FIG. 59 that the antibacterial capabil-ity increased to a value ++ by adding 0.12 ~g/cm2 or more of Cu, and to a value of +++ by adding 0.3 ~,g/cm2 or more of Cu.
It is known that Cu itself has an antibacterial action. Therefore, even upon non-irradiation, the antibac-terial capability increases when the amount of carried Cu is increased. Upon non-irradiation, the antibacterial capabil-ity increased to a value of ++ by adding 0.7 ~tg/cm2 or more of Cu, and to a value of +++ by adding 1.2 ~.g/cmz or more of Cu.

~ 5522 Consequently, the good antibacterial capability upon irradiation (L) with the amount of carried Cu being of 0.12 ~tg/cmz or more and less than 0.7 ~.g/cmz at the ++ level and being of 0.3 pg/cmz or more and less than 1.2 p.g/cm2 at the +++ level is considered to be a special effect resulting from the combination of Cu and the thin rutile TiOz film.
The presence of the thin rutile TiOZ film is effective to reduce the amount of carried Cu. Being able to reduce the amount of carried Cu is an important nature to be relied upon especially when the composite material is to be used with water. Therefore, when the composite material is used in an environment in which Cu is eluted into water, e.g., when the composite material is used in a basin or a bowl of sanitary ware, the amount of eluted Cu can be reduced.
The same advantages of Cu can be achieved when Cu is incorporated in the form of Cu20, because Cu having a va-lence of 1 is detected on the surface upon photoreduction by ESCA and a photoactivity recovering effect is observed even though the conversion Cu?' -~ Cu' is partly carried out.
A good antibacterial capability can be accom-plished when the amount of carried Cu is of 0.7 ~tg/cmz or more, and more preferably 1.2 ~,g/cm2 or more, irrespective of whether the assembly is irradiated with light or not.
FIG. 60 shows the relationship the amount of Cu that was coated and the amount of Cu that was carried when the concentration of Cu in the solution was 1 wt ~. It can be seen from FIG. 60 that the amount of carried Cu did not 21~~~22 increase simply by increasing the amount of coated Cu, and the amount of coated Cu may be of 0.2 mg/cm2 or more and 2.7 mg/cm2 and less in order to increase the amount of carried Cu to 0.7 ~.g/cm2 or. more, and the amount of coated Cu may be of 0.3 mg/cm2 or more and 2.4 mg/cm2 and less in order to in-crease the amount of carried Cu to 1.2 ~tg/cm2 or more.
(Inventive Example 51) A dispersion in ammonia of Ti02 sol having an av-erage diameter of 0.01 ~tm was coated on a square tile base with each side 15 cm long by spray coating and then fired at 900°C, forming a thin rutile TiOz film having a thickness of 0.8 Eun. Then, aqueous solutions of silver nitrate which had respective solution concentrations of 0.2 weight %, 0.5 weight %, and 1 weight % were coated in varying amounts on the thin rutile TiOz film by spray coating, and thereafter photoreduced by a light source comprising a 20W BLB lamp for 30 seconds, thus producing specimens. The light source was spaced from the specimens by a distance of 10 cm. The specimens were evaluated for an antibacterial capability.
The amounts of carried Ag were determined by collecting the remaining aqueous solutions after being irradiated and cal-culating the difference between the initial amounts of sil-ver and the collected amounts of silver.
FIG. 61 shows the relationship between the amount of carried Ag and the bacteria survival ratios upon irradia-tion (L) and nan-irradiation (D). Study of FIG. 61 reveals the following:

2155~?2 Unlike the example using Cu, the curves of the bacteria survival ratios upon irradiation (L) and non-irradiation (D) were superimposed one on the other. This is not because the example using Ag produced results different from those of the example using Cu, but because the antibac-terial capability of Ag is much greater than the antibacte-rial capability of Cu, and is achieved with a very small amount of Ag, w:ith the result that the difference between required amounts of carried Ag upon irradiation (L) and non-irradiation (D) falls in an experimental error range.
It can be seen from FIG. 61 that a good antibacte-rial capability can be accomplished when the amount of car-ried Ag is of 0.05 ~g/cm2 or more, and more preferably 0.1 ~g/cm2 or more, irrespective of whether the assembly is irra-diated with light or not.
FIG. 62 shows the relationship between the amount of carried silver and the color difference with a specimen with no silver carried. When the amount of carried silver exceeded 1 ~g/cmz, the color difference sharply increased in excess of 2. Generally, the difference between colors stands out when the color difference reaches 2 or more.
when silver is attached, the color changes from brown to black, which is not preferable as the appearance becomes unsightly. Therefore, it is preferable to keep the color difference at 2 or less, and to this end, the amount of car-ried silver may be reduced to 1 ~g/cm2 or smaller. The color .__ 215522 difference was measured by a spectral color difference meter (manufactured by Tokyo Denshoku R.R.).
It has been disclosed in the above example to cover active sites of fine particles having a photocatalytic activity with fine metal particles of silver, copper, plati-num, palladium, gold, nickel, iron, cobalt, zinc, or the like in order to prevent the activity from being lowered by a surface-treating agent, high-molecular substances, dust particles which would otherwise cover the active sites of the photocatalyst or to recover the activity. Since these metals are colored metals, if any of these metals were coated in a large amount, a certain color would be applied to the surface of the base, and designs of the base, such as the color, pattern, etc. thereof, would be impaired.
A decolorizing process for preventing designs of the base, such as the color, pattern, etc. thereof, from being impaired while maintaining a high level of photocata-lytic activity will be described below.
The decolorizing process is basically composed of two steps, i.e., the step of fixing fine metal particles to photocatalytic particles, and the step of reacting the fine metal particles with an aqueous solution or a gas to produce a colorless or white salt on at least the surfaces of the fine metal particles, for thereby preparing a catalyst con-taining fine metal particles.
These two steps may be carried out in any order, and either one of the steps may be carried out first. Spe-._ 21~~g~2 cifically, after colored fine metal particles may be fixed to photocatalytic particles, the fine metal particles may be reacted with an aqueous solution or a gas to produce a col-orless or white salt on at least the surfaces of the fine metal particles, or after colored fine metal particles may be reacted with an aqueous solution or a gas to produce a colorless or white salt on at least the surfaces of the fine metal particles, the colored fine metal particles may be fixed to photocatalytic particles.
Alternatively, after photocatalytic particles and colored fine metal particles may be mixed with each other, the mixture may be fixed to a base. This process may be composed, for example, of the successive steps of mixing photocatalytic particles and colored fine metal particles with each other, coating the mixture solution to a base, firing the assembly to fix the mixture to the base, and re-acting the assembly with a gas to produce a colorless or white salt on at least the surfaces of the fine metal parti-cles.
The steps of firing the assembly to fix the mix-ture to the base and reacting the assembly with a gas to produce a colorless or white salt on at least the surfaces of the fine metal particles may be carried out simultane-ously.
The colored fine metal particles comprise fine metal particles of a metal which has a small ionizing ten-dency and tends to be reduced itself, such as silver, cop-... 215822 per, platinum, palladium, gold, nickel, iron, cobalt, zinc, or the like.
If a colorless or white salt is produced by react-ing the colored fine metal particles with an aqueous solu-tion, or if a catalyst containing fine metal particles is used in a liquid, the produced colorless or white salt should be hardly soluble or insoluble.
If a catalyst containing fine metal particles is fixed to a base for use, then photocatalytic particles may be fixed to the base and then a catalyst containing fine metal particles may be prepared, or a catalyst containing fine metal particles may be prepared and thereafter fixed to the base.
If photocatalytic particles are be fixed to a base and then a catalyst containing fine metal particles is pre-pared, then the process should be composed of the successive steps of forming a photocatalytic particle layer on the base, fixing colored fine metal particles to the photocata-lytic particle layer, and producing a colorless or white salt in covering relationship to the colored fine metal par-ticles.
The step of producing a colorless or white salt in covering relationship to the colored fine metal particles may be carried out, for example, by either bringing, into contact with the fine metal particles, a solution which re-acts with the colored fine metal particles to produce a col-orless or white salt on at least the surfaces of the fine 2I~~822 metal particles, or bringing, into contact with the fine metal particles, a reactive gas which reacts with the col-ored fine metal- particles to produce a colorless or white salt on at least the surfaces of the fine metal particles.
The white or colorless salt of the colored fine metal particles should preferably be a hardly soluble or insoluble salt because it can easily be formed on at least the surfaces of the fine metal particles by a reaction with the aqueous solution and can stably be used in water-rich environments.
The white or colorless salt of the colored fine metal particles may be, for example, silver chloride, silver bromide, silver iodide, silver oxalate, silver thiosulfate, silver cyanide, silver rhodanide, cuprous chloride, cuprous bromide, cuprous cyanide, cuprous rhodanide, cuprous oxide, zinc phosphate, zinc oxalate, zinc cyanide, palladium cya-nide, zinc sulfide, zinc carbonate, ferrous carbonate, zinc oxide, or the like. The solution capable of producing the salt may be a solution of potassium chloride, a solution of sodium chloride, a solution of ammonium chloride, a solution of ferric chloride, or the like if the salt is silver chlo-ride, or a solution of potassium iodide, a solution of so-dium iodide, a solution of ferric iodide, hydrogen peroxide water, ozone water, or the like. However, the solution ca-pable of producing the salt is not limited to any of these solutions, but may be any of various solutions of soluble salt containing various negative salt ions.

21~~g22 The reactive gas capable of producing the salt may be any of various gases containing various negative salt ion elements. For example, if the salt is an oxide such as zinc oxide, cuprous oxide, or the like, then the oxide may be heated in the atmosphere, oxygen, or water vapor or reacted with an oxidizing agent such as 03 or the like thereby to oxidize the surfaces of the fine metal particles to form an oxide layer thereon.
Specific examples will be described below.
(Inventive Example 52) A sol of titanium oxide having an average diameter of 0.01 dun was coated on the surface of a square tile base with each side 15 cm long, and heated at 900°C, producing a specimen with a thin rutile titanium oxide film. The speci-men produced at this stage is referred to as a comparative specimen 1. An aqueous solution of silver nitrate was coated on the comparative specimen 1 by spray coating, and irradiated by a light source comprising a 20W BLB lamp for minutes, fixing silver to the thin rutile titanium oxide film. The amount of carried silver was 1.2 ~,g/cmz, and the carried silver was colored brown. The specimen produced at this stage is referred to as a comparative specimen 2.
Thereafter, 0.1 mol/liter of an aqueous solution of potassium iodide was coated on the comparative specimen 2 at a rate of 0.1 cc/cmz and reacted therewith. As a result, the color of the specimen surface changed to yellowish white because of a silver iodide layer formed thereon. The speci-21~58?2 men produced at this stage is referred to as an inventive specimen 1.
These specimens were evaluated for color differ-ence, photoactivity, deodorizing and antibacterial capabili-ties.
The color difference was measured by a spectral color difference meter (manufactured by Tokyo Denshoku R.R.) with the comparative specimen 1 used as a standard specimen.
The results are shown in FIG. 63. The comparative specimen 2 had a color difference of 3.5, whereas the inventive specimen 1 had a color difference of 1 because it was treated with the aqueous solution of potassium iodide. The degree of coloring of the inventive specimen 1 was thus re-duced.
The photoactivity was evaluated by a OpH test.
The results of the evaluation of the photoactivity and the deodorizing capability are shown in FIG. 64. A comparison of the comparative specimens 1, 2 indicates that because silver was carried, the comparative specimen 2 recovered the photoactivity and had good values for OpH and R3o(L). A com-parison of the inventive specimen 1 and the comparative specimen 2 shows that they have substantially the same val-ues for ApH and R3o(L), their photoactivity remained un-changed even after the decolorizing process and maintained good characteristics.
With respect to the antibacterial capability, each of the specimens was tested for its antibacterial ability 21~5~~2 against escherichia coli, strain: W3110. Specifically, 0.15 ml (2 x 10' CFU) of the bacterial solution was dropped onto the outermost surface of the specimen which had been steril-ized with 70 ~ ethanol, and a glass sheet (100 x 100 mm) was placed in intimate contact with the outermost surface of the base, thus preparing a specimen. After the specimen was irradiated with light from a white-light lamp with 3500 luxes for a given period of time, the bac::erial solution on the irradiated specimen (L) and the bacterial solution on a specimen (D) kept under a shielded condition were wiped with a sterile gauze, and collected in 10 ml of physiological saline. The number of live bacteria was checked for evalua-tion.
The results of the evaluation of the antibacterial capability are shown in FIG. 65. Since the comparative ex-ample 1 carried no silver, no antibacterial capability was confirmed upon non-irradiation (D). Aowever, the inventive specimen 1 exhibited an antibacterial capability upon non-irradiation (D) even through the silver surface was changed to a compound by the decolorizing process. Upon irradiation (L), the inventive specimen 1 exhibited a stronger antibac-terial capability, indicating the recovery of the photocata-lytic activity of the thin rutile titanium film as well as the antibacterial activity of silver.
(Inventive Example 53) After a glaze was coated on a square blank for forming sanitary ware, with ease side 15 cm long, the blank 215~~~2 was fired at a temperature ranging from 1100 to 1200°C.
Thereafter, a sol of anatase titanium oxide having an aver-age particle diameter of 0.01 ~tm was coated on the glazed blank, and fired at a temperature ranging from 900 to 1000°C, fixing a thin rutile titanium oxide film on the base of the blank.
Thereafter, an aqueous solution of silver nitrate was coated on the thin rutile titanium oxide film, and irra-diated with ultraviolet rays to separate out silver on the thin titanium oxide film. Then, an aqueous solution of fer-ric chloride was coated on the silver layer, and irradiated with ultraviolet rays, whereupon the specimen was decol-orized, with the color difference reduced from 3 to 0.3.
The antibacterial capability was tested by bringing both specimens which were treated by irradiation and non-irradiation into contact with bacteria for 30 minutes, and exhibited a goad result as it was confirmed that only less ~ of the original bacterial survived.
(Inventive Example 54) After a glaze was coated on a square blank for forming sanitary ware, with ease side 15 cm long, the blank was fired at a temperature ranging from 1100 to 1200°C.
Thereafter, a sol of anatase titanium oxide having an aver-age particle diameter of 0.01 u.m was coated on the glazed blank, and fired at a temperature ranging from 900 to 1000°C, fixing a thin rutile titanium oxide film on the base of the blank.

._ 2I ~~822 TherEaafter, an aqueous solution of silver nitrate was coated on the thin rutile titanium oxide film, and irra-diated with ultraviolet rays to separate out silver on the thin titanium oxide film. Then, the specimen was decol-orized by being left to stand for about two hours in a des-iccator with an. ozonizer in which the concentration of ozone was 10 ppm. The antibacterial capability of the specimen exhibited a goad result as it was confirmed that only 10 %
of the original. bacterial brought into contact with the specimen survived.
(Inventive Example 55) After a glaze was coated on a square blank for forming sanitary ware, with ease side 15 cm long, the blank was fired at a temperature ranging from 1100 to 1200°C.
Thereafter, a mixture of an aqueous solution of silver ni-trate and a so7_ of anatase titanium oxide having an average particle diameter of 0.01 Eun and dispersed in an aqueous solution of nitric acid was coated on the glazed blank, and fired, fixing a thin titanium oxide film on the base of the blank. At this time, when the specimen was fired at a tem-perature less i:han 700°C, the specimen was colored brown, and when the specimen was fired at a temperature of 700°C or higher, the specimen was decolorized. This is because the silver surface reached with a component in the atmosphere.
A specimen which was fired at 850°C to fix a thin anatase titanium oxide film to the base of the blank was measured for its antibacterial capability. The antibacterial capa-__ 215~~22 bility was tested by bringing both specimens which were treated by irradiation and non-irradiation into contact with bacteria for three hours, and exhibited a good result as it was confirmed that only less than 10 % of the original bac-terial survived.
(Inventive Example 56) After a glaze was coated on a square blank for forming sanitary ware, with ease side 15 cm long, the blank was fired at a temperature ranging from 1100 to 1200°C.
Thereafter, a sol of anatase titanium oxide having an aver-age particle diameter of 0.01 ~.m was coated on the glazed blank, and fired at a temperature ranging from 900 to 1000°C, fixing a thin rutile titanium oxide film on the base of the blank.
Thereafter, an aqueous solution of silver nitrate was coated on the thin rutile titanium oxide film, and irra-diated with ultraviolet rays to separate out silver on the thin titanium oxide film. When hydrogen peroxide water was coated on the silver layer, the specimen was decolorized.
The antibacterial capability was tested by bringing both specimens which were treated by irradiation and non-irradiation into contact with bacteria for three hours, and exhibited a good result as it was confirmed that only less than 10 % of th.e original bacterial survived.
A process of mixing rutile Ti02 particles and tin oxide with each. other to increase the density and adhesion of a thin photos:atalytic film and improve its photoactivity will be described below.
The thin photocatalytic film may be formed by ei-ther one of the following two processes:
According to one process, a sol of Ti02 and a sol of tin oxide are mixed with each other, and the mixture is coated on the surface of a base and fired.
The sol of TiOZ and the sol of tin oxide are mixed with each other in a basic aqueous solution because both are well dispersed in an electrochemically alkaline solution.
The basic aqueous solution may be ammonia or a hydroxide including an alkaline metal or an alkaline earth metal.
Particularly preferable is ammonia because it will not pro-duce a metal contaminant after being heated. To the disper-sion, there may be added a dispersant of organic acid or phosphoric acid,, a surface-treating agent, and a surface-active agent.
Processes of coating the mixture of the Ti02 sol and the sol of tin oxide include spray coating, dip coating, rolling coating, spin coating, CVD, electron beam evapora-tion, and sputtering. The mixture of the TiOZ sol and the sol of tin oxide may be coated by any of these processes or any of other processes. The spray coating, dip coating, and roll coating processes are advantageous as they require no special equipment and can form coatings inexpensively as compared with CVD, electron beam evaporation, sputtering, or the like.

After being coated, the film may be dried before it is fired. The film may be dried at a temperature ranging from room temperature to 110°C.
The film is fired at a temperature high enough to generate a ruti:le structure under the above condition. The temperature is .830°C or higher under normal pressure in the presence of tin oxide.
It is not necessary to form a solid solution of Ti02 and tin oxide because formation of a solid solution of TiOz and tin oxide requires them to be held at a high tem-perature for a :Long period of time, resulting in a poor pro-duction efficiency.
According to the other process, after a thin ru-tile Ti02 film is formed, a sol of tin oxide is added to thereto and then fired.
In this process, a starting material including Ti is first coated on a base. The starting material may be a Ti02 sol, a Ti alkoxide, a sulfate of Ti, a chloride solution of Ti, or the like. If a TiOz sol is employed, then since Ti02 has an isoE~lectric point of pH 6.5 and hence is substan-tially neutral, it can easily be coated uniformly on the base in the form of an aqueous solution in which it is dis-persed by an acid or alkali. If the base is of metal, then an alkaline dispersion is preferable from the standpoint of erosion resistance. If the base is of pottery, tile, ce-ramic, or the like, then either an acid dispersion or an alkaline dispersion may be employed. The acid may be a ni-21~~822 tric acid, a sulfuric acid, a hydrochloric acid, an acetic acid, a phosphoric acid, an organic acid, or the like. The alkaline aqueous solution may be ammonia or a hydroxide in-cluding an alkaline metal or an alkaline earth metal. Par-ticularly preferable is ammonia as it will not produce a metal contaminant after being heated. To the dispersion, there may be added a dispersant of organic acid or phospho-ric acid, a surface-treating agent, and a surface-active agent. The average particle diameter of the Ti02 sol of the starting material should be 0.05 Eun or smaller, and prefera-bly be 0.01 Eun or smaller. Since smaller particle diameters allow an initial sintering phase to occur at a lower tem-perature, a thin photocatalytic film having an excellent peel strength a.t a low temperature can be produced. Proc-esses of coating the starting material include spray coat-ing, dip coating, rolling coating, spin coating, CVD, elec-tron beam evaporation, and sputtering. The starting mate-rial may be coated by any of these processes or any of other processes. The spray coating, dip coating, and roll coating processes are advantageous as they require no special equip-ment and can form coatings inexpensively as compared with CVD, electron beam evaporation, sputtering, or the like.
After being coated, the film may be dried before it is fired. The film may be dried at a temperature ranging f rom room temperature to 110°C .

2I~~~22 Then, the coated composite material is fired at a temperature high enough to generate a rutile structure. The temperature is !~00°C or higher under normal pressure.
Thereafter, a starting material serving as a source of Sn is coated on the composite material which has been cooled and solidified, and then fired. The starting material as a source of Sn may be a sol of tin oxide. The sol of tin oxide may be in a basic ac~aeous solution because the sol of tin oxide is stable in an electrochemically alka-line solution. The basic aqueous solution may be ammonia or a hydroxide including an alkaline metal or an alkaline earth metal. Particularly preferable is ammonia because it will not produce a metal contaminant after being heated. To the dispersion, there may be added a dispersant of organic acid or phosphoric acid, a surface-treating agent, and a surface-active agent. Processes of coating the starting material include spray coating, dip coating, rolling coating, spin coating, CVD, electron beam evaporation, and sputtering.
The starting material may be coated by any of these proc-esses or any of other processes. The spray coating, dip coating, and roll coating processes are advantageous as they require no special equipment and can form coatings inexpen-sively as compared with CVD, electron beam evaporation, sputtering, or the like. After being coated, the film may be dried before it is fired. The film may be dried at a temperature ranging from room temperature to 110°C. The film is fired apt a temperature high enough to vaporize an _a 2155822 added organic component from tin oxide. The temperature is 300°C or higher under normal pressure. It is not necessary to form a solid solution of Ti02 and tin oxide because forma-tion of a solid solution of Ti02 and tin oxide requires them to be held at a high temperature for a long period of time, resulting in a poor production efficiency.
A than film composed of a mixture of rutile Ti02 and tin oxide having a crystal diameter of less than 0.01 ~tm may be formed on the surface of the base, and at least one metal of Cu, Act, Pt, Fe, Co, Ni, Pd, and Cu02 may be fixed to the thin layer., These metals have an electron-capturing effect to increase the photocatalytic activity of the thin film com-posed of a mixture of rutile TiOZ and tin oxide having a crystal diameter of less than 0.01 ~tm.
Since the metals of Cu, Ag are antibacterial them-selves and can be given a non-irradiated activity with re-spect to an antibacterial capability, it is possible to make the composite material antibacterial even if not irradiated with light. At least one metal of Cu, Ag, Pt, Fe, Co, Ni, Pd, and Cu2o is fixed by coating an aqueous solution of salt of one of the 'metals and then photoreducing or heating the coated salt.
The aqueous solution of metal salt may basically contain the metal as positive ions, and may specifically be an aqueous solution of copper acetate, silver nitrate, cop-per carbonate, copper sulfate, cuprous chloride, cupric . - 210 -_ 2155822 chloride, chloroplatinic acid, palladium chloride, nickel chloride, cobalt chloride, ferrous chloride, or ferric chlo-ride.
The aqueous solution of metal salt may be coated by spray coating or dip coating. However, the dip coating process is preferable because the amount of solution used is small, the aqueous solution can be coated uniformly, the film thickness can easily be ccatrolled, and it is possible not to coat the reverse side of the base.
If photoreduction is relied on, the coated aqueous solution of metal salt is irradiated with light containing ultraviolet rays to reduce metal ions for thereby fixing at least one metal. of Cu, Ag, Pt, Fe, Co, Ni, Pd, and Cu.20 to the thin fi7Lm composed of a mixture of rutile Ti02 and tin oxide having a crystal diameter of less than 0.01 ~tm.
The .Light source for radiating light containing ultraviolet rays may be any light source which is capable of radiating light: containing ultraviolet rays, and may spe-cif ically be an ultraviolet lamp, a BLB lamp, a xenon lamp, a mercury lamp, or a fluorescent lamp. It is preferable to position the specimen such that the light containing ultra-violet rays wi7_1 perpendicularly be applied to the surface to be irradiatE~d because the irradiation efficiency is the greatest. The specimen should preferably be spaced from the light source by a distance ranging from 1 cm to 30 cm. If the distance between the specimen and the light source were too small, then light would not be applied with uniform i1-x- 211 -2 l 55822 luminance to the entire surface of the specimen, and the metal would irregularly be attached. If the distance be-tween the specimen and the light source were too large, then since the illuminance of the applied light is in inverse proportion to the square of the distance, the metal would not firmly be attached.
If the heating process is relied on, then the coated salt is heated to a temperature high enough to fix the metal. The temperature should be 100°C or higher. How-ever, if the coated salt is heated at a temperature of 800°C
or higher, them the metal will be oxidized. Therefore, met-als that can bE~ used are limited to those which will not lose an electron-capturing effect or an antibacterial capa-bility when oxidized, i.e., to Ag and Cu. Since Ag and Cu do not lose their electron-capturing effect or antibacterial capability when fired at high temperatures, it is possible to employ a manufacturing process composed of the steps of mixing a sol of Ti02 and a sol of tin oxide with each other, coating the mixture is coated on the surface of a base, then coating an aqueous solution of metal salt, and firing the coated metal salt. According to this process, since only one firing step is involved, the productivity is increased and the manufa<auring cost is reduced.
Specific examples will be described below.
(Inventive Example 57) 4 ~ 6 weight % of a sol of Ti02 having a crystal diameter of 0.01 Etm was added to an aqueous solution of am-monia which had been adjusted to a pH of 11, thus producing a suspension A in a container. 10 weight ~ of a sol of tin oxide having a crystal diameter of 0.0035 ~.un was added to an aqueous solution of ammonia which had been adjusted to a pH
of 11, thus producing a suspension B in another container.
The suspensions A, B were mixed with each other at a given ratio, and the mixture was coated on the surface of a square tile base with each side 15 cm long by spray coating. Then, the coated mixture was dried and thereafter fired at 850°C
for two hours, forming a specimen. The crystalline type of Ti02 in the produced specimen was of a rutile structure.
When the lattices constant of Ti02 was measured by powder X-ray diffraction, no solid solution of tin oxide in the TiOZ
lattice was recognized. The specimen was evaluated for its photoactivity and wear resistance.
The plzotoactivity was evaluated by dropping an aqueous solution of potassium iodide onto the surface of the specimen, irradiating the dropped aqueous solution of potas-sium iodide with ultraviolet rays for 30 minutes, and deter-mining the difference between the pH of the aqueous solution of potassium iodide before it was irradiated and the pH of the aqueous solution of potassium iodide after it was irra-diated. If the photoactivity of the specimen surface is higher, then thEa following oxidizing and reducing reactions are accelerated at a higher rate, and the pH of the aqueous solution before after it is irradiated is higher than the pH
of the aqueous solution before it is irradiated.

21~~g2~
Oxidizing reaction: 2I- + 2h' - IZ
Reducing reaction: OZ + 2H20 + 4e - 40H-The wear resistance was evaluated by rubbing the specimen with a plastic eraser, and comparing any change in the appearance thereof. Evaluation indications O, O, O, x used were the same as those described above.
FIG. 66 show how the wear resistance changed with respect to the weight ratio of tin oxide in the thin film.
The wear resistance had good results of O, O irrespective of whether tin oxide existed or not. This is because the heat treatment at the high temperature of 850°C brought about sintering,, firmly bonding particles to each other in the film.
The wear resistance had a value of O when the proportion of tin oxide exceeded 30 %. Since the ratio be-tween the parti<:le diameters of the sol of Ti02 (whose crys-tal diameter was of 0.01 ~tm) and the sol of tin oxide (whose crystal diameter was of 0.0035 ~tm) was more than 2, the fine particles of tin oxide filled interstices between the parti-cles of Ti02, with the result that the filling capability of the film increased and the film was made more dense.
FIG. 67 illustrates how the photoactivity changed with respect to the weight ratio of tin oxide in the thin film. For comparison, FIG. 67 also shows ~pH of a specimen in which Cu was carried by rutile Ti02 and which exhibited good antibacterial and deodorizing capabilities (60 % in terms of R3o ) and ~pH of a specimen composed of anatase Ti02 2 ~ ~~822 which exhibited very good antibacterial and deodorizing ca-pabilities (95 ~ in terms of R3o). While the OpH of the ru-tile Ti02 specimen with tin oxide added was lower than the OpH of the anatase TiO~ specimen, the OpH of the rutile Ti02 specimen with tin oxide added was greater than the ~pH of the specimen with Cu carried by rutile Ti02 if the weight ratio of added tin oxide was in excess of 10 ~ and less than 80 ~, preferably of 20 ~ oL more and 70 ~ or less. There-fore, the rutile TiOz specimen with tin oxide added exhibited a good photoact.ivity.
The photocatalytic activity was not increased even by adding tin oxide having an average particle diameter of 0.01 ~tm or more: because the particles of tin oxide had no band gap sufficient to generate active oxygen since any up-ward shift of t:he position of the conduction band due to conversion of t:in oxide into fine particles was not suffi-cient. No sufficient photoactivity was created unless the weight ratio of: tin oxide exceeded 10 ~ because the weight ratio of particles of tin oxide was not enough. The pho-toactivity was reduced when the weight ratio of tin oxide reached 80 ~ or more presumably for the reason that since the probability that particles of tin oxide in the photo-catalytic layer existed adjacent to each other was high, they grew highly frequently into particles whose average diameter was 0.01 Wn or more when heated.
(Comparative Example 58) 2I5~~?2 4 - 6 weight % of a sol of Ti02 having a crystal diameter of 0.01 dun was added to an aqueous solution of am-monia which had been adjusted to a pH of 11, thus producing a suspension A in a container. 10 weight % of a sol of tin oxide having a crystal diameter of 0.01 um was added to an aqueous solution of ammonia which had been adjusted to a pH
of 11, thus producing a suspension B in another container.
The suspensions A, B were mixed with each other at a given ratio, and the :mixture was coated on the surface of a square tile base with each side 15 cm long by spray coating. Then, the coated mixture was dried and thereafter fired at 850°C
for two hours, forming a specimen. The crystalline type of Ti02 in the produced specimen was of a rutile structure.
When the lattice constant of TiOz was measured by powder X-ray diffraction, no solid solution of tin oxide in the TiOz lattice was recognized. The specimen was evaluated for its photoactivity and wear resistance.
FIG. 68 show how the wear resistance changed with respect to the 'weight ratio of tin oxide in the thin film.
The wear resistance had a good result of O irrespective of whether tin oxide existed or not. This is because the heat treatment at the high temperature of 850°C brought about sintering, firmly bonding particles to each other in the film. However, the wear resistance was not increased fur-ther when the amount of added tin oxide was increased. This is because the particle diameters of the sol of TiOz (whose crystal diameter was of 0.01 dun) and the sol of tin oxide (whose crystal diameter was of 0.01 ~.m) were substantially equal to each other.
FIG. 69 illustrates how the photoactivity changed with respect to the weight ratio of tin oxide in the thin film. For comparison, FIG. 69 also shows OpH of a specimen in which Cu was carried by rutile TiOz and which exhibited good antibacterial and deodorizing capabilities and OpH of a specimen composed of anatase Ti02 which exhibited very good antibacterial a.nd deodorizing capabilities). The OpH of the rutile Ti02 specimen with tin oxide added was much lower than the OpH of the anatase Ti02 specimen and the ~pH of the specimen with C:u carried by rutile Ti02.
(Inventive Example 59) 4 -- ti weight % of a sol of Ti02 having a crystal diameter of 0.01 ~tm was added to an aqueous solution of am-monia which had been adjusted to a pH of 11, thus producing a suspension A in a container. 10 weight % of a sol of tin oxide having a crystal diameter of 0.0035 dun was added to an aqueous solution of ammonia which had been adjusted to a pH
of 11, thus producing a suspension B in another container.
The suspensionsc A, B were mixed with each other at a given ratio, and the mixture was coated on the surface of a square tile base with each side 15 cm long by spray coating. Then, the coated mixi;ure was dried and thereafter fired at 850°C
for two hours, forming a composite material. The crystal-line type of TiOz in the produced composite material was of a rutile structure. The weight ratio of tin oxide in the thin x film was 60 %. When the lattice constant of Ti02 was meas-ured by powder :K-ray diffraction, no solid solution of tin oxide in the Tit~2 lattice was recognized. Then, an aqueous solution of 5 weight % of copper acetate was coated on the composite material by spray coating, dried, and thereafter photoreduced by a light source comprising a 20W BLB lamp for one minute, thus producing a specimen. The light source was spaced from the specimen by a distance of 10 cm. The speci-men was evaluated for its deodorizing capability R3o~
The deodorizing capability R3o was determined by the following test. A gas to be decomposed was methyl mer-captan, and the specimen was placed in a cylindrical con-tainer having a diameter of 26 cm and a height of 21 cm and in which an initial concentration of methyl mercaptan was adjusted to 2 ppm. A deodorizing capability R,o(L) upon ir-radiation was determined by placing the specimen at a dis-tance of 8 cm from a 4W BLB fluorescent lamp, irradiating the specimen with light from the 4W BLB fluorescent lamp for 30 minutes, and then calculating a rate at which the concen-tration of methyl mercaptan was reduced. A deodorizing ca-pability R3o(D) upon non-irradiation was determined by leav-ing the specimen non-irradiated with light for 30 minutes, and then calculating a rate at which the concentration of methyl mercaptan was reduced. The determined deodorizing capabilities are given in Table 26 below. For comparison, the specimens (in which the weight ratio of tin oxide was 60 %) prepared in Inventive Example 55 and Comparative Example ~. 2I5~~22 56 were also te:nted. It can be seen from Table 26 that the specimen according to this example exhibits effects de-scribed below blur the addition of Cu.
(Table 26) Spec imen R3o ( L ) R3o ( D ) Inventive Examp:Le 82 0 Inventive Examp:Le 97 92 Comparative Example32 0 It can be understood from Table 26 that the de-odorizing capability R3o(L) was slightly better than that of the specimen according to Inventive Example 53. It is con-sidered that the deodorizing capability R3o(L) was improved by the electron-capturing effect of Cu. The deodorizing capability R~(D) was much better than those of the specimens according to Inventive Example 53 and Comparative Example 54. It is considered that this increase in the activity upon non-irradiation was caused by the catalytic effect of copper.
As described above, when a material with a thin , photocatalytic :film formed on the surface of a base is proc-essed at a firing temperature high enough to convert a Ti02 component in the thin photocatalytic film into a rutile structure, a Ti~~Z film is rendered sufficiently dense and strong. If the thin photocatalytic film contains tin oxide having a crystal diameter of less than 0.01 ~.tm other than the rutile Ti02,, then the photocatalytic activity of the thin photocatalytic film is increased.

The photocatalytic activity can further be in-creased by an e7_ectron-capturing action when at least one metal of Cu, Ag, Pt, Fe, Co, Ni, and Pd is fixed to the thin photocatalytic i:ilm.
INDUSTRIAL APPL7:CABILITY:
As described above, a multi-functional material having an antibacterial capability, a stain-resistant capa-bility, deodorizing capability, and a photocatalytic capa-bility for decomposing harmful substances such as NOx can suitably be usedl as a wall material, a tile, glass, mirror, a stone-like material which can be used as a stepstone around an artificial fall or a fountain equipped with a cir-culatory filter device, e.g., a water circulation system, or sanitary ware such as a closet bowl, a basin, or the like, a hospital equipment material for preventing bacterial infec-tions such as MR.SA or the like in hospitals, a home service equipment material, a mold-resistant material, a virus-resistant material, or the like.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. 1. A multi-functional material exhibiting a photocatalytic function, comprising: a base and a photocatalytic layer having a photocatalytic function and disposed on a surface of said base; said photocatalytic layer including at least a surface layer exposed outwardly; said surface layer comprising fine photocatalytic particles intimately joined together in abutting relationship such that pores are defined therebetween at a predetermined porosity;
said photocatalytic layer being disposed on the surface of said base through a binder layer interposed therebetween; said photocatalytic layer including a surface layer exposed outwardly and a lower layer embedded in said binder layer;
said multi-functional material being a multi-functional glass;
said base being made of soda glass; and said binder layer containing a smaller quantity of alkali-metal component than said base.

2. A multi-functional material exhibiting a photocatalytic function, comprising: a base and a photocatalytic layer having a photocatalytic function and disposed on a surface of said base; said photocatalytic layer including at least a surface layer exposed outwardly; said surface layer comprising fine photocatalytic particles intimately joined together in abutting relationship such that pores are defined therebetween at a predetermined porosity;

said photocatalytic layer being disposed on the surface of said base through a binder layer interposed therebetween; said photocatalytic layer including a surface layer exposed outwardly and a lower layer embedded in said binder layer;
said multi-functional material being a multi-functional glass;
said base being made of soda glass; and said binder layer being made of silica.

3. A multi-functional material according to claim 2, wherein said material is heat-treated in a range of 300°-500°C. to embed the portion of the lower layer of the photocatalytic layer in the binder layer.

4. A multi-functional material exhibiting a photocatalytic function, comprising: a base and a photocatalytic layer having a photocatalytic function and disposed on a surface of said base; said photocatalytic layer including at least a surface layer exposed outwardly; said surface layer comprising fine photocatalytic particles intimately joined together in abutting relationship such that pores are defined therebetween at a predetermined porosity;
said photocatalytic layer being disposed on the surface of said base through a binder layer interposed therebetween; said photocatalytic layer including a surface layer exposed outwardly and a lower layer embedded in said binder layer;
said multi-functional material being a multi-functional glass;
said multi-functional material being a multi-functional glass; and said photocatalytic layer being produced by hydrolyzing titanium alkoxide to obtain titanium hydroxide, dehydrolyzing and condensing the titanium hydroxide, and further crystallizing the titanium hydroxide.

5. A method of manufacturing a multi-functional material exhibiting a photocatalytic function, comprising the steps of: forming a photocatalytic layer of photocatalytic particles on a substantially planar binder layer of thermoplastic material; placing or applying said substantially planar binder layer to a surface of a base;
thereafter softening said binder layer to embed a portion of a lower layer of the photocatalytic layer in the binder layer; and solidifying said binder layer;
said binder layer having a softening temperature lower than a softening temperature of said base, and said step of softening the binder layer involves heating the binder layer at an atmospheric temperature which is higher than the softening temperature of said binder layer by X, where 20°<X<320°C., and lower than the softening temperature of said base.

6. A method according to claim 5, wherein X satisfies the equation 40°C ~ X ~300°C.

7. A method according to claim 5, wherein the step of softening the binder layer involves hot pressing of the photocatalytic layer and the binder layer to embed the portion of the lower layer of the photocatalytic layer in the binder layer.

8. A method of manufacturing a multi-functional material exhibiting a photocatalytic function, comprising the steps of: dispersing a sol, a precursor, or a suspension of photocatalytic particles in a solution with a dispersant to form a dispersion, forming a photocatalytic layer of the photocatalytic particles using the dispersion on a substantially planar binder layer of thermoplastic material; placing or applying said substantially planar binder layer to a surface of a base;
thereafter softening the binder layer to embed a portion of a lower layer of the photocatalytic layer in the binder layer; and solidifying the binder layer;
said dispersant consisting of a component which is vaporized at a temperature lower than a heat-treatment temperature at which said binder layer is softened.

9. A method of manufacturing a multi-functional material exhibiting a photocatalytic function, comprising the steps of:
forming a photocatalytic layer of photocatalytic particles on a substantially planar binder layer of thermoplastic material; placing or applying said substantially planar binder layer to a surface of a base;
thereafter softening said binder layer to embed a portion of a lower layer of the photocatalytic layer in the binder layer, and solidifying said binder layer;
said photocatalytic particles and said binder layer having respective specific gravities .delta.t, .delta.b which satisfy the relationship: 0.~delta.t-.delta.b~3Ø

10. A method according to claim 9, wherein said photocatalytic layer is disposed on the surface of said base through first and second binder layers interposed therebetween, said first binder layer being disposed on said base and said second binder layer being disposed on said first binder layer, and said photocatalytic particles and said second binder layer have said respective specific gravities .delta.t,.delta.b which satisfy the relationship: 0~.delta.t-.delta.b~3Ø