US3779784A - COMPOSITE FIBERS OF ALKALI METAL HEXATITANATE AND RUTILE TiO{11 - Google Patents
COMPOSITE FIBERS OF ALKALI METAL HEXATITANATE AND RUTILE TiO{11 Download PDFInfo
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- US3779784A US3779784A US00241681A US3779784DA US3779784A US 3779784 A US3779784 A US 3779784A US 00241681 A US00241681 A US 00241681A US 3779784D A US3779784D A US 3779784DA US 3779784 A US3779784 A US 3779784A
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- alkali metal
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- 239000000835 fiber Substances 0.000 title abstract description 59
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N titanium dioxide Inorganic materials O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 title abstract description 33
- 239000002131 composite material Substances 0.000 title abstract description 30
- 229910052783 alkali metal Inorganic materials 0.000 title abstract description 23
- 150000001340 alkali metals Chemical class 0.000 title abstract description 17
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 title description 20
- 239000002657 fibrous material Substances 0.000 abstract description 7
- 239000004033 plastic Substances 0.000 abstract description 5
- 229920003023 plastic Polymers 0.000 abstract description 5
- 230000003014 reinforcing effect Effects 0.000 abstract description 4
- 238000000034 method Methods 0.000 description 15
- 239000000047 product Substances 0.000 description 11
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 11
- 239000000203 mixture Substances 0.000 description 9
- -1 alkali metal titanate Chemical class 0.000 description 8
- XFVGXQSSXWIWIO-UHFFFAOYSA-N chloro hypochlorite;titanium Chemical compound [Ti].ClOCl XFVGXQSSXWIWIO-UHFFFAOYSA-N 0.000 description 7
- 239000002210 silicon-based material Substances 0.000 description 7
- 238000002386 leaching Methods 0.000 description 6
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 5
- 229920001131 Pulp (paper) Polymers 0.000 description 5
- 239000011449 brick Substances 0.000 description 5
- 238000001354 calcination Methods 0.000 description 5
- NJLLQSBAHIKGKF-UHFFFAOYSA-N dipotassium dioxido(oxo)titanium Chemical compound [K+].[K+].[O-][Ti]([O-])=O NJLLQSBAHIKGKF-UHFFFAOYSA-N 0.000 description 5
- 239000012153 distilled water Substances 0.000 description 5
- 229910052700 potassium Inorganic materials 0.000 description 5
- 239000011591 potassium Substances 0.000 description 5
- 150000003839 salts Chemical class 0.000 description 5
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 3
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 3
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 239000002253 acid Substances 0.000 description 3
- 238000013019 agitation Methods 0.000 description 3
- 235000021028 berry Nutrition 0.000 description 3
- 229910052796 boron Inorganic materials 0.000 description 3
- 229910000040 hydrogen fluoride Inorganic materials 0.000 description 3
- 239000000123 paper Substances 0.000 description 3
- 239000002245 particle Substances 0.000 description 3
- 238000002360 preparation method Methods 0.000 description 3
- 239000004408 titanium dioxide Substances 0.000 description 3
- 238000005406 washing Methods 0.000 description 3
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- 238000002441 X-ray diffraction Methods 0.000 description 2
- 150000008044 alkali metal hydroxides Chemical class 0.000 description 2
- 229910000272 alkali metal oxide Inorganic materials 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 2
- 150000001642 boronic acid derivatives Chemical class 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 239000012774 insulation material Substances 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- BWHMMNNQKKPAPP-UHFFFAOYSA-L potassium carbonate Chemical compound [K+].[K+].[O-]C([O-])=O BWHMMNNQKKPAPP-UHFFFAOYSA-L 0.000 description 2
- 230000002787 reinforcement Effects 0.000 description 2
- 238000009877 rendering Methods 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- BTBUEUYNUDRHOZ-UHFFFAOYSA-N Borate Chemical compound [O-]B([O-])[O-] BTBUEUYNUDRHOZ-UHFFFAOYSA-N 0.000 description 1
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 description 1
- 239000004698 Polyethylene Substances 0.000 description 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 229910000288 alkali metal carbonate Inorganic materials 0.000 description 1
- 150000008041 alkali metal carbonates Chemical class 0.000 description 1
- 229910001508 alkali metal halide Inorganic materials 0.000 description 1
- 150000008045 alkali metal halides Chemical class 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 230000001627 detrimental effect Effects 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 239000010433 feldspar Substances 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 239000005357 flat glass Substances 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- QYFRTHZXAGSYGT-UHFFFAOYSA-L hexaaluminum dipotassium dioxosilane oxygen(2-) difluoride hydrate Chemical compound O.[O--].[O--].[O--].[O--].[O--].[O--].[O--].[O--].[O--].[F-].[F-].[Al+3].[Al+3].[Al+3].[Al+3].[Al+3].[Al+3].[K+].[K+].O=[Si]=O.O=[Si]=O.O=[Si]=O.O=[Si]=O.O=[Si]=O.O=[Si]=O QYFRTHZXAGSYGT-UHFFFAOYSA-L 0.000 description 1
- 239000008240 homogeneous mixture Substances 0.000 description 1
- 238000010348 incorporation Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000011812 mixed powder Substances 0.000 description 1
- 230000019612 pigmentation Effects 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 1
- 239000004810 polytetrafluoroethylene Substances 0.000 description 1
- 229910000027 potassium carbonate Inorganic materials 0.000 description 1
- CHWRSCGUEQEHOH-UHFFFAOYSA-N potassium oxide Chemical compound [O-2].[K+].[K+] CHWRSCGUEQEHOH-UHFFFAOYSA-N 0.000 description 1
- 229910001950 potassium oxide Inorganic materials 0.000 description 1
- 239000011541 reaction mixture Substances 0.000 description 1
- 239000005368 silicate glass Substances 0.000 description 1
- 150000004760 silicates Chemical class 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- 230000004580 weight loss Effects 0.000 description 1
Images
Classifications
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
- C04B41/009—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone characterised by the material treated
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B20/00—Use of materials as fillers for mortars, concrete or artificial stone according to more than one of groups C04B14/00 - C04B18/00 and characterised by shape or grain distribution; Treatment of materials according to more than one of the groups C04B14/00 - C04B18/00 specially adapted to enhance their filling properties in mortars, concrete or artificial stone; Expanding or defibrillating materials
- C04B20/10—Coating or impregnating
- C04B20/1055—Coating or impregnating with inorganic materials
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/62227—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products obtaining fibres
- C04B35/62231—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products obtaining fibres based on oxide ceramics
- C04B35/62259—Fibres based on titanium oxide
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
- C04B41/45—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements
- C04B41/50—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements with inorganic materials
- C04B41/5025—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements with inorganic materials with ceramic materials
- C04B41/5041—Titanium oxide or titanates
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
- C04B41/80—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone of only ceramics
- C04B41/81—Coating or impregnation
- C04B41/85—Coating or impregnation with inorganic materials
- C04B41/87—Ceramics
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K7/00—Use of ingredients characterised by shape
- C08K7/02—Fibres or whiskers
- C08K7/04—Fibres or whiskers inorganic
- C08K7/08—Oxygen-containing compounds
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K9/00—Use of pretreated ingredients
- C08K9/10—Encapsulated ingredients
-
- D—TEXTILES; PAPER
- D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
- D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
- D01F8/00—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T442/00—Fabric [woven, knitted, or nonwoven textile or cloth, etc.]
- Y10T442/60—Nonwoven fabric [i.e., nonwoven strand or fiber material]
- Y10T442/608—Including strand or fiber material which is of specific structural definition
- Y10T442/614—Strand or fiber material specified as having microdimensions [i.e., microfiber]
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T442/00—Fabric [woven, knitted, or nonwoven textile or cloth, etc.]
- Y10T442/60—Nonwoven fabric [i.e., nonwoven strand or fiber material]
- Y10T442/608—Including strand or fiber material which is of specific structural definition
- Y10T442/614—Strand or fiber material specified as having microdimensions [i.e., microfiber]
- Y10T442/622—Microfiber is a composite fiber
Definitions
- the fibers have a core of alkali metal hexatitanate encapsulated by a shell of rutile TiO, and are essentially inert to aqueous 5% by weight HF solution.
- the fibrous material is particularly useful in the reinforcing of plastics.
- fibrous materials are useful as reinforcing components for plastics, ceramics and cermets.
- Other uses include insulation materials and additives during paper manufacture.
- a fibrous material composed of composite fibers having a number average diameter of up to about 10 microns and an average length/diameter ratio of at least about 5/1, said fibers having a core composition corresponding to the formula wherein M is an alkali metal of atomic number of at ieast 1 1, said core being encapsulated by a shell of rutile TiO thereby rendering the fibers essentially inert to aqueous by weight HF solution.
- the individual composite fibers possess the combined strength of the alkali metal hexatitanate and rutile components. In addition they tend to be less expensive to prepare, more dense, and more stable to acid and elevated temperatures than are the alkali metal titanates. It is known, for example, that when ordinary potassium titanate fibers are heated to a temperature over 900 C., they start to lose potassium oxide and some strength.
- the rutile titanium dioxide shell of the composite fibers of the present invention minimizes the loss of alkali at high temperatures. Since the outer shell of these composite fibers is rutile titanium dioxide, the fibers are characterized by the higher refractive index of titanium dioxide, i.e.
- the refractive index of rutile TiO is about 2.7] compared to the refractive index of potassium titanate which is about 2.35. This higher refractive index of the composite fibers is important when the fibers are to be used in a system where high opacity is a desired characteristic.
- the presence of the alkali metal hexatitanate and rutile TiO components in the composite fibers can be readily confirmed by X-ray analysis techniques as both components are characterized by distinct X-ray diffraction patterns.
- the existence of the core/shell composite structure is readily confirmed by treating the fibers with a 5% by weight HF solution. A true composite is virtually unaffected by the treatment since rutile TiO is essentially inert to the action of 5% or even HF solution. If the fibers were a homogeneous mixture of alkali metal hexatitanate and rutile TiO or if the alkali metal hexatitanate was otherwise in the shell portion, considerable dissolution and weight loss would occur.
- the actual percentage of rutile TiO as a shell about the core of alkali metal hexatitanate is not critical pro vided that the amount be such as to ensure inertness to the action of 5% by weight HF solution.
- the alkali metal titanate should constitute at least l0% and, preferably at least 50%, by weight of the composite fibers.
- Example l Various processes can be used for preparing the composite fibers.
- the resultant alkali metal titanate fibers can then be converted to composite fibers by calcining, for example, at 1,000 C., in the presence of a boronor silicon-containing compound such as Na, 8 0 K B 0 B 0 Na SiO muscovite mica, or feldspar.
- the composite fibers form directly, apparently as a result of the reaction of the boronor silicon-containing compound with the alkali metal oxide in the surface portion of the alkali metal titanate fibers.
- alkali metal titanate fibers may be initially formed by the procedure described above but with the inclusion of one of the aforementioned boronor silicon-containing compounds in the dry blended mix before calcining. This method is illustrated in Example ll hereinafter.
- a third method involves direct formation of the composite fibers from a mixture of an alkali metal hydroxide, titanium oxychloride, and one of the silicaor boron-containing compounds described above.
- a salt-gel is formed of the various components, which is calcined at a temperature of 850 C. to 1,050" C. More particularly, the salt-gel is prepared by admixing concentrated aqueous alkali metal hydroxide solution, e.g. KOH or NaOH, and aqueous titanium oxychloride solution (e.g.
- the mixing preferably being carried out by means of a high speed, high shear mixer.
- one solution is conveniently added to the other in relative amounts such that a pH of at least 9, preferably of l0-l 0.5, is reached, at which point a thick salt-gel is formed.
- the salt'gel is then cast in a suitable container and, preferably, dried.
- the resultant porous brick is subsequently calcined at a temperature in the range from 850 C. to L050 C. and then leached, e.g. with water or aqueous liquids, to produce the composite fibers.
- the amount of boron or silicon-containing compound that need be so employed will vary depending upon which particular process is selected. Moreover, the amount will affect, at least to some extent, the thickness of the TiO shell which is formed. Too little may result in an unduly thin TiO shell, which in turn may fail to give the requisite inertness to a HF solu' tion. Large quantities of the boronor silicon containing compound will, conversely, tend to produce a relatively thick shell of TiO This is not particularly detrimental, however, except from the standpoint that the economics may be less favorable. In general, it is satisfactory to employ some 5 to 50% by weight of the boronor silicon-containing compound based on the weight of the composite fiber which is formed.
- the utility of the composite fibers will depend, at least in part, upon their particle size. Smaller size particles, say of 0.1 to 0.6 micron in diameter, are useful for the pigmentation of paper, plastics, fibers and the like. Larger size particles, most commonly of 0.6 to 3 microns in diameter, but occasionally up to microns in diameter, are useful in the reinforcement of plastics or as insulation materials.
- the composite fibers should have aspect ratios, i.e. L/D ratios of at least 5 to l but more preferably to l. Aspect ratios of l00-l,000 to l are not uncommon.
- FIG. 1 is a photomicrograph at 4,200X of composite t ⁇ Ti,,() rutile fibers prepared by the salt-gel method of Example IV with the incorporation of both gotassium borate and paper pulp in the reaction mixture.
- a 04 gr. portion of the potassium titanate fibers are wet mixed with 0.6 gr. of wet ground plate glass (silicate glass).
- the mixture is then dried and placed in a furnace.
- the temperature is raised to 900 C. over a period of about 2 hours and kept at that temperature for hour.
- the product is removed from the furnace, and eached in 5% by weight HF with agitation for 3 days. After settling, decanting the clear liquor, filtering, washing with water and drying, the product is subjected to analysis.
- Xray analysis demonstrates that the product is composed of K 'li o and rutile TiO, in a ratio estimated 0 be about if].
- the fibers are found to have an L/D ratio of about l00:l. They are in the pig mentary range, i.e. with a fiber diameter of about (H to 0.6 microns.
- the core/shell structure is confirmed by the inertness to 5% by weight HF solution in water.
- Microscopically the product is found to have an average length of about 10 microns, an average diameter of about 0.1 to 0.2 micron and a surface area of 7.3 M lg.
- the fibers are found to be composed of a predominately potassium hexatitanate core and an outer rutile TiO shell.
- EXAMPLE III Fifty grams of KOH is added to 50 cc. distilled water to prepare a concentrated KOH solution which is then placed in a Waring Blendor along with 15 grams K B O While agitation is maintained, a titanium oxychloride solution (considered to be represented by the formula TiOCI- 'ZHCI) is added until a pH of 10 is reached.
- the titanium oxychloride solution is prepared by mixing TiCl and ice in a 31'] weight ratio. The amount of titanium oxychloride solution so required is 150 grams.
- the salt-gel thus prepared is cast into a glass vessel lined with polytetrafluoroethylene and dried for 4 hours at 200 C. A porous brick is formed which is then calcined for minutes at 900 C.
- the calcined brick is leached free of soluble salts by washing with hot distilled water. Fourteen grams of a fibrous product are thereby obtained. X-rays reveal that the product, which has a surface area of 9.5 Mlgn, contains both rutile and potassium hexatitanate. Examined microscopically, the composite fibers are found to have an average diameter of about 0.1 micron and an L/D ratio of about 200.
- EXAMPLE IV The procedure is the same as that of Example III except that 10 grams of wet paper pulp (20% solids) is added to the KOH solution along with the 15 grams of K B O In this case the potassium hexatitanatel'l'iO composite fibers have a surface area of 17 M /gr. and length and diameter dimensions similar to the fibers of Example [11.
- FIG. 1 is a photomicrograph of the fibers at 4,200x.
- EXAMPLE V Fifty grams of KOH is added to 50 cc. distilled water to prepare a concentrated KOH solution. The concentrated KOH solution is placed in a Waring Blendor along with grams of wet paper pulp (20% solids) and 10 grams of a titanium oxychloride solution prepared as in Example Ill. While agitation is maintained, more of the titanium oxychloride solution is added until a pH of 10 is reached, this requiring grams of the solution.
- the salt-gel thus prepared is cast and dried as in Example lll.
- the porous brick thus formed is subsequently calcined for 1 hour at 950 C.
- the calcined brick is leached free of soluble salts by washing with hot distilled water. A 10% hydrogen fluoride solution is then used over a period of 2 hours to dissolve away the silicates generated in the calcination step. The treatment otherwise leaves the fibers essentially unchanged.
- the recovered composite fibers have a surface area of l5 Mlgr. and X-rays reveal the presence of both rutile and potassium hexatitanate components.
- the fibers have length and diameter dimensions similar to those of Example Ill.
- a fibrous material composed of composite fibers having a number average diameter of up to about l0 microns and an average length/diameter ratio of at least about Sll, said fibers having a core composition corresponding to the formula wherein M is an alkali metal of atomic number of at least 1 1, said core being encapsulated by a shell of rutile TiO, thereby rendering the fibers essentially inert to aqueous 5% by weight HF solution.
Abstract
A fibrous material is provided which is composed of composite fibers having a number average diameter of up to about 10 microns and an average length/diameter ratio of at least about 5/1. The fibers have a core of alkali metal hexatitanate encapsulated by a shell of rutile TiO2 and are essentially inert to aqueous 5% by weight HF solution. The fibrous material is particularly useful in the reinforcing of plastics.
Description
United States Patent [191 Emslie, deceased COMPOSITE FIBERS OF ALKALI METAL HEXATITANATE AND RUTILE TH);
[75] Inventor: Robert Steele Emslle. deceased, late of Chadds Ford, Pa. by Jean McPhaul Emslie, administratrix [73] Assignee: E. l. DuPont de Nemours and Company, Wilmington. Del.
[22] Filed: Apr. 6, 1972 [2i] Appl. No.: 241,681
[52] US. Cl. 106/300, l06/308 B [5] Int. Cl. C091: 1/36 [58] Field of Search 106/300. 308 B [56] References Cited UNITED STATES PATENTS 3338.677 8/l967 Berry 106/300 l Dec. 18, 1973 3,703.357 ll/l972 Surls et al. l06/300 Primary Examiner-Curtis R. Davis Al!orneyDonald A. Hoes [S 7] ABSTRACT A fibrous material is provided which is composed of composite fibers having a number average diameter of up to about 10 microns and an average length/diameter ratio of at least about 5/1. The fibers have a core of alkali metal hexatitanate encapsulated by a shell of rutile TiO, and are essentially inert to aqueous 5% by weight HF solution. The fibrous material is particularly useful in the reinforcing of plastics.
1 Claim, 1 Drawing Figure l5 MICRONS COMPOSITE FIBERS OF ALKALI METAL HEXATTTANATE AND RUTILE T102 BACKGROUND OF THE INVENTION Water-insoluble, fibrous alkali metal titanates having the formula M O(TiO where M is an alkali metal of atomic number of at least I l, and n is a number of from 4 to 8 and their preparations are disclosed in U.S. Pat. Nos. 2,833,620, Gier et al.; 2,841,470, Berry; 3,328,117, Emslie et al.; and 3,33l,658, Lewis et al.
The preparation of fibrous titanium dioxide is described in U.S. Pat. Nos. 3,0l2,857, Pease; 3,065,091, Russell; 3,24l,928, Pease; and 3,244,481, Berry.
Also mixtures of pigmentary titanium dioxide and fibrous alkali metal titanates are disclosed in U.S. Pat No. 3,484,260, Emslie et al.
These fibrous materials are useful as reinforcing components for plastics, ceramics and cermets. Other uses include insulation materials and additives during paper manufacture.
It is known that fibrous titanates will tend to deteriorate in certain acid atmospheres and that improvements in this and other properties would be desirable.
SUMMARY OF THE INVENTION In accordance with the invention there is provided a fibrous material composed of composite fibers having a number average diameter of up to about 10 microns and an average length/diameter ratio of at least about 5/1, said fibers having a core composition corresponding to the formula wherein M is an alkali metal of atomic number of at ieast 1 1, said core being encapsulated by a shell of rutile TiO thereby rendering the fibers essentially inert to aqueous by weight HF solution.
The individual composite fibers possess the combined strength of the alkali metal hexatitanate and rutile components. In addition they tend to be less expensive to prepare, more dense, and more stable to acid and elevated temperatures than are the alkali metal titanates. It is known, for example, that when ordinary potassium titanate fibers are heated to a temperature over 900 C., they start to lose potassium oxide and some strength. The rutile titanium dioxide shell of the composite fibers of the present invention minimizes the loss of alkali at high temperatures. Since the outer shell of these composite fibers is rutile titanium dioxide, the fibers are characterized by the higher refractive index of titanium dioxide, i.e. the refractive index of rutile TiO is about 2.7] compared to the refractive index of potassium titanate which is about 2.35. This higher refractive index of the composite fibers is important when the fibers are to be used in a system where high opacity is a desired characteristic.
The presence of the alkali metal hexatitanate and rutile TiO components in the composite fibers can be readily confirmed by X-ray analysis techniques as both components are characterized by distinct X-ray diffraction patterns. The existence of the core/shell composite structure is readily confirmed by treating the fibers with a 5% by weight HF solution. A true composite is virtually unaffected by the treatment since rutile TiO is essentially inert to the action of 5% or even HF solution. If the fibers were a homogeneous mixture of alkali metal hexatitanate and rutile TiO or if the alkali metal hexatitanate was otherwise in the shell portion, considerable dissolution and weight loss would occur.
The actual percentage of rutile TiO as a shell about the core of alkali metal hexatitanate is not critical pro vided that the amount be such as to ensure inertness to the action of 5% by weight HF solution. Normally the alkali metal titanate should constitute at least l0% and, preferably at least 50%, by weight of the composite fibers.
The fact that the TiO shell about the alkali metal hexatitanate core is in the rutile crystalline phase serves to distinguish the products of the invention from prior art products in which alkali metal titanate fibers may have been leached with acid to remove a portion of the alkali metal oxide from the surface; i.e. such leaching would not result in a distinct TiO shell of the rutile crystalline phase.
Various processes can be used for preparing the composite fibers. One technique, to be described in Example l hereinafter, involves the preparation of alkali metal titanate fibers in the usual way. This may be accomplished, for example, by calcining a dry blended mixture of anatase TiO alkali metal carbonate and alkali metal halide followed by leaching of the calcined product to remove soluble salts. The resultant alkali metal titanate fibers can then be converted to composite fibers by calcining, for example, at 1,000 C., in the presence of a boronor silicon-containing compound such as Na, 8 0 K B 0 B 0 Na SiO muscovite mica, or feldspar. The composite fibers form directly, apparently as a result of the reaction of the boronor silicon-containing compound with the alkali metal oxide in the surface portion of the alkali metal titanate fibers.
Alternatively, alkali metal titanate fibers may be initially formed by the procedure described above but with the inclusion of one of the aforementioned boronor silicon-containing compounds in the dry blended mix before calcining. This method is illustrated in Example ll hereinafter.
Still a third method, and one which wqll be illustrated in Examples lll through V hereinafter, involves direct formation of the composite fibers from a mixture of an alkali metal hydroxide, titanium oxychloride, and one of the silicaor boron-containing compounds described above. In this case, a salt-gel is formed of the various components, which is calcined at a temperature of 850 C. to 1,050" C. More particularly, the salt-gel is prepared by admixing concentrated aqueous alkali metal hydroxide solution, e.g. KOH or NaOH, and aqueous titanium oxychloride solution (e.g. as prepared from the reaction of TiCl, and ice), the mixing preferably being carried out by means of a high speed, high shear mixer. In the process, one solution is conveniently added to the other in relative amounts such that a pH of at least 9, preferably of l0-l 0.5, is reached, at which point a thick salt-gel is formed. The salt'gel is then cast in a suitable container and, preferably, dried. The resultant porous brick is subsequently calcined at a temperature in the range from 850 C. to L050 C. and then leached, e.g. with water or aqueous liquids, to produce the composite fibers.
Regardless of the method employed, simple leaching of the resultant fibers appears to remove essentially all residual compounds containing boron or silicon. Thus, borates tend to be converted to higher borates in the process and these are generally soluble in the water used as a leaching agent. Where a silicon-containing compound has been employed, the use of an aqueous HP leaching solution may be necessary to remove un' desired silicate byproducts.
The amount of boron or silicon-containing compound that need be so employed will vary depending upon which particular process is selected. Moreover, the amount will affect, at least to some extent, the thickness of the TiO shell which is formed. Too little may result in an unduly thin TiO shell, which in turn may fail to give the requisite inertness to a HF solu' tion. Large quantities of the boronor silicon containing compound will, conversely, tend to produce a relatively thick shell of TiO This is not particularly detrimental, however, except from the standpoint that the economics may be less favorable. In general, it is satisfactory to employ some 5 to 50% by weight of the boronor silicon-containing compound based on the weight of the composite fiber which is formed.
Each of the processes results in a composite fiber in which the titanate is essentially in the hexa-crystalline form. apparently because that species is the most thermally stable species.
The utility of the composite fibers will depend, at least in part, upon their particle size. Smaller size particles, say of 0.1 to 0.6 micron in diameter, are useful for the pigmentation of paper, plastics, fibers and the like. Larger size particles, most commonly of 0.6 to 3 microns in diameter, but occasionally up to microns in diameter, are useful in the reinforcement of plastics or as insulation materials. In general the composite fibers should have aspect ratios, i.e. L/D ratios of at least 5 to l but more preferably to l. Aspect ratios of l00-l,000 to l are not uncommon.
DESCRIPTION OF THE DRAWING FIG. 1 is a photomicrograph at 4,200X of composite t\ Ti,,() rutile fibers prepared by the salt-gel method of Example IV with the incorporation of both gotassium borate and paper pulp in the reaction mixture.
EXAMPLES To illustrate the invention more completely, the following examples are given. These are for purposes of illustration only and are not to be construed as limitalion of the invention.
EXAMPLE I Pigmentary size fibers of potassium titanate are produced by the general procedure described in Emslie et =1l. US. Pat. No. 3,328,l l7 involving the calcination of potassium carbonate, anatase TiO and KCl.
A 04 gr. portion of the potassium titanate fibers are wet mixed with 0.6 gr. of wet ground plate glass (silicate glass). The mixture is then dried and placed in a furnace. The temperature is raised to 900 C. over a period of about 2 hours and kept at that temperature for hour. The product is removed from the furnace, and eached in 5% by weight HF with agitation for 3 days. After settling, decanting the clear liquor, filtering, washing with water and drying, the product is subjected to analysis.
Xray analysis demonstrates that the product is composed of K 'li o and rutile TiO, in a ratio estimated 0 be about if]. Microscopically the fibers are found to have an L/D ratio of about l00:l. They are in the pig mentary range, i.e. with a fiber diameter of about (H to 0.6 microns. The core/shell structure is confirmed by the inertness to 5% by weight HF solution in water.
EXAMPLE II A blend is prepared by micronizing together the following components:
300 grams anatasc TiO, I00 grams K,CCi
200 grams KCl The mixed powder is then added to wet paper pulp I00 grams total weight 20% paper pulp fibers) and rolled in a four liter vessel for l hour. Balls form that are about l2 cm. in diameter and are made up of the paper pulpingredient mixture. These balls are calcined for 2 hours at ],000 C. The composite fibers are then recovered by leaching away the soluble salts with dilute sulfuric acid.
Microscopically the product is found to have an average length of about 10 microns, an average diameter of about 0.1 to 0.2 micron and a surface area of 7.3 M lg. The fibers are found to be composed of a predominately potassium hexatitanate core and an outer rutile TiO shell.
EXAMPLE III Fifty grams of KOH is added to 50 cc. distilled water to prepare a concentrated KOH solution which is then placed in a Waring Blendor along with 15 grams K B O While agitation is maintained, a titanium oxychloride solution (considered to be represented by the formula TiOCI- 'ZHCI) is added until a pH of 10 is reached. The titanium oxychloride solution is prepared by mixing TiCl and ice in a 31'] weight ratio. The amount of titanium oxychloride solution so required is 150 grams.
The salt-gel thus prepared is cast into a glass vessel lined with polytetrafluoroethylene and dried for 4 hours at 200 C. A porous brick is formed which is then calcined for minutes at 900 C.
The calcined brick is leached free of soluble salts by washing with hot distilled water. Fourteen grams of a fibrous product are thereby obtained. X-rays reveal that the product, which has a surface area of 9.5 Mlgn, contains both rutile and potassium hexatitanate. Examined microscopically, the composite fibers are found to have an average diameter of about 0.1 micron and an L/D ratio of about 200.
Five grams of the product is placed in 10% aqueous hydrogen fluoride solution in a polyethylene beaker. After 2 hours of stirring, the fibrous product is recovered, washed with distilled water, and dried. It is found to be essentially unchanged. This demonstrates that the rutile effectively encapsulates a potassium hexatitanate core since it is known that potassium titanate alone would be completely soluble in 10% hydrogen fluoride solution.
EXAMPLE IV The procedure is the same as that of Example III except that 10 grams of wet paper pulp (20% solids) is added to the KOH solution along with the 15 grams of K B O In this case the potassium hexatitanatel'l'iO composite fibers have a surface area of 17 M /gr. and length and diameter dimensions similar to the fibers of Example [11. FIG. 1 is a photomicrograph of the fibers at 4,200x.
EXAMPLE V Fifty grams of KOH is added to 50 cc. distilled water to prepare a concentrated KOH solution. The concentrated KOH solution is placed in a Waring Blendor along with grams of wet paper pulp (20% solids) and 10 grams of a titanium oxychloride solution prepared as in Example Ill. While agitation is maintained, more of the titanium oxychloride solution is added until a pH of 10 is reached, this requiring grams of the solution.
The salt-gel thus prepared is cast and dried as in Example lll. The porous brick thus formed is subsequently calcined for 1 hour at 950 C.
The calcined brick is leached free of soluble salts by washing with hot distilled water. A 10% hydrogen fluoride solution is then used over a period of 2 hours to dissolve away the silicates generated in the calcination step. The treatment otherwise leaves the fibers essentially unchanged.
The recovered composite fibers have a surface area of l5 Mlgr. and X-rays reveal the presence of both rutile and potassium hexatitanate components. The fibers have length and diameter dimensions similar to those of Example Ill.
EXAMPLE VI Composite fibers prepared by the methods described in Examples II and III are tested for their reinforcing strength in a commercial, high density, linear polyeth- FLEX TEST RESULTS Sample Flex Strength-psi Flex Moduluspsi Control No fiber reinforcement 4.500 150,000 Example ll fibers 7,320 1 290 594,000 1* 40,000 Example III fibers 6,450 :2 230 427,000 1 17,000
What is claimed is:
l. A fibrous material composed of composite fibers having a number average diameter of up to about l0 microns and an average length/diameter ratio of at least about Sll, said fibers having a core composition corresponding to the formula wherein M is an alkali metal of atomic number of at least 1 1, said core being encapsulated by a shell of rutile TiO, thereby rendering the fibers essentially inert to aqueous 5% by weight HF solution.
I I I I.
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Application Number | Priority Date | Filing Date | Title |
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US24168172A | 1972-04-06 | 1972-04-06 |
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US3779784A true US3779784A (en) | 1973-12-18 |
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US00241681A Expired - Lifetime US3779784A (en) | 1972-04-06 | 1972-04-06 | COMPOSITE FIBERS OF ALKALI METAL HEXATITANATE AND RUTILE TiO{11 |
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Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3956006A (en) * | 1973-02-08 | 1976-05-11 | Bayer Aktiengesellschaft | Composite pigment of isometric rutile and acicular modified potassium hexatitanate |
US4605594A (en) * | 1984-08-08 | 1986-08-12 | Minnesota Mining And Manufacturing Company | Ceramic articles having a nonporous core and porous outer layer |
US4664971A (en) * | 1981-12-30 | 1987-05-12 | N.V. Bekaert S.A. | Plastic article containing electrically conductive fibers |
US5407754A (en) * | 1991-06-20 | 1995-04-18 | Titan Kogyo Kabushiki Kaisha | Potassium hexatitanate fibers for use as reinforcement |
EP0684215A1 (en) * | 1993-02-22 | 1995-11-29 | Kubota Corporation | Composite fibers of potassium hexatitanate and titanium dioxide |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3338677A (en) * | 1967-08-29 | Brookite fibers and their preparation | ||
US3703357A (en) * | 1971-07-28 | 1972-11-21 | Dow Chemical Co | Process for the preparation of rutile titanium dioxide needles |
-
1972
- 1972-04-06 US US00241681A patent/US3779784A/en not_active Expired - Lifetime
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3338677A (en) * | 1967-08-29 | Brookite fibers and their preparation | ||
US3703357A (en) * | 1971-07-28 | 1972-11-21 | Dow Chemical Co | Process for the preparation of rutile titanium dioxide needles |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3956006A (en) * | 1973-02-08 | 1976-05-11 | Bayer Aktiengesellschaft | Composite pigment of isometric rutile and acicular modified potassium hexatitanate |
US4664971A (en) * | 1981-12-30 | 1987-05-12 | N.V. Bekaert S.A. | Plastic article containing electrically conductive fibers |
US4605594A (en) * | 1984-08-08 | 1986-08-12 | Minnesota Mining And Manufacturing Company | Ceramic articles having a nonporous core and porous outer layer |
US5407754A (en) * | 1991-06-20 | 1995-04-18 | Titan Kogyo Kabushiki Kaisha | Potassium hexatitanate fibers for use as reinforcement |
EP0684215A1 (en) * | 1993-02-22 | 1995-11-29 | Kubota Corporation | Composite fibers of potassium hexatitanate and titanium dioxide |
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