CA2191621A1 - Use of reduced interference pigments in producing forgery-proof security documents - Google Patents
Use of reduced interference pigments in producing forgery-proof security documentsInfo
- Publication number
- CA2191621A1 CA2191621A1 CA002191621A CA2191621A CA2191621A1 CA 2191621 A1 CA2191621 A1 CA 2191621A1 CA 002191621 A CA002191621 A CA 002191621A CA 2191621 A CA2191621 A CA 2191621A CA 2191621 A1 CA2191621 A1 CA 2191621A1
- Authority
- CA
- Canada
- Prior art keywords
- pigments
- color
- interference
- scattering
- interference pigments
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
- B41M3/00—Printing processes to produce particular kinds of printed work, e.g. patterns
- B41M3/14—Security printing
- B41M3/144—Security printing using fluorescent, luminescent or iridescent effects
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
- B41M3/00—Printing processes to produce particular kinds of printed work, e.g. patterns
- B41M3/14—Security printing
- B41M3/148—Transitory images, i.e. images only visible from certain viewing angles
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B42—BOOKBINDING; ALBUMS; FILES; SPECIAL PRINTED MATTER
- B42D—BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS
- B42D25/00—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof
- B42D25/30—Identification or security features, e.g. for preventing forgery
- B42D25/36—Identification or security features, e.g. for preventing forgery comprising special materials
- B42D25/378—Special inks
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
- C09C1/00—Treatment of specific inorganic materials other than fibrous fillers; Preparation of carbon black
- C09C1/0015—Pigments exhibiting interference colours, e.g. transparent platelets of appropriate thinness or flaky substrates, e.g. mica, bearing appropriate thin transparent coatings
- C09C1/0021—Pigments exhibiting interference colours, e.g. transparent platelets of appropriate thinness or flaky substrates, e.g. mica, bearing appropriate thin transparent coatings comprising a core coated with only one layer having a high or low refractive index
-
- G—PHYSICS
- G07—CHECKING-DEVICES
- G07D—HANDLING OF COINS OR VALUABLE PAPERS, e.g. TESTING, SORTING BY DENOMINATIONS, COUNTING, DISPENSING, CHANGING OR DEPOSITING
- G07D7/00—Testing specially adapted to determine the identity or genuineness of valuable papers or for segregating those which are unacceptable, e.g. banknotes that are alien to a currency
- G07D7/003—Testing specially adapted to determine the identity or genuineness of valuable papers or for segregating those which are unacceptable, e.g. banknotes that are alien to a currency using security elements
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/20—Particle morphology extending in two dimensions, e.g. plate-like
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/80—Particles consisting of a mixture of two or more inorganic phases
- C01P2004/82—Particles consisting of a mixture of two or more inorganic phases two phases having the same anion, e.g. both oxidic phases
- C01P2004/84—Particles consisting of a mixture of two or more inorganic phases two phases having the same anion, e.g. both oxidic phases one phase coated with the other
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
- C09C2200/00—Compositional and structural details of pigments exhibiting interference colours
- C09C2200/10—Interference pigments characterized by the core material
- C09C2200/102—Interference pigments characterized by the core material the core consisting of glass or silicate material like mica or clays, e.g. kaolin
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
- C09C2200/00—Compositional and structural details of pigments exhibiting interference colours
- C09C2200/30—Interference pigments characterised by the thickness of the core or layers thereon or by the total thickness of the final pigment particle
- C09C2200/302—Thickness of a layer with high refractive material
Abstract
Interference pigments based on silicate laminae that are coated with titanium dioxide and heated in a reduced atmosphere are used to produce forgery-proof security documents and packaging.
Description
0050t4~900 .
Use of interference pigments containing reduced titanium oxide layers for preparing forgeryproof documents and p~k~gi ng 5 The present invention relates to the use of specific interference pigments based on titanium dioxide-coated silicatic platelets which have been heated in a reducing atmosphere, in combination with scattering color pigments or scattering white pigments, for preparing forgeryproof documents and r~k~g; n7, The forgeryproofing of documents such as paper money, postage stamps, checks, tax stamps, checkcards, rail or air tickets, credit cards, t~l~ph~n~ cards, lottery tickets, share certifi-cates, gift vouchers, passes or identity cards is becoming more 15 and more important in view of the introductlon of evermore power-ful color copiers and the attendant scope for forgery. The same is true of valuable pa~kAg; ng.
Forgeryproofness has in the past been pursued in various ways.
20 For instance, the originals were marked using magnetic pigments~_ or fluorescent dyes. Eowever, these markings have the disadvan-tage that their presence is not immediately r~ogni 7~hl e visu-ally; they can only be detected using appropriate, more or less complex, reading apparatus. The same is true of marking with IR
25 or UV dyes or pigments.
Greater interest therefore pertains to marks which are suffi-ciently reliably r~o7n;7~hle with the unaided, naked eye and make it easy to distinguish the copy from the original. In prac-30 tice this kind of mark has taken the form of water marks - sil-very bright metal strips which show up black in the copy owing to the total reflection of the light - or holograms. However, the disadvantage of these marks is that they are easy to imitate or, in the case of holograms, costly and prone to damage.
The most recent addition to the ways of marking authenticity is the use of simple interference pigments. ~owever, applied atop a light-colored ground, interference pigments are virtually invis-ible, the exact field of the identifying mark iB difficult to 40 make out, and the markings are c~.,seyuently easily overlooked.
Interference pigments in the conventional sense (described for example in U5-A-3 087 827 are plateletlike luster pigments con-sisting y~ n~ntly of a mica substrate coated with a layer of 45 highly refractive material, eg. rutile, zirconium dioxide or tin dioxide, in a certain th;okn~s (generally >50 nm) to form thin platelet colors. Interference pigments have to be applied in an Amended sheet ' 0050~44900 ~ 2 oriented state. However, the intensity of the color of interference color pigments is low compared with that of scatter-ing color pigments. They have an angle-dependent reflection maxi-mum. Interference pigments of this type have for many years been 5 used in cosmetics and plastics.
There have also been ~;crlos~d multi-layer pigments which exhibit a distinct angle-de~l.dent color change and are produced by pul-verizing thin film security devices - thin multi-layer films de-10 tached from the substrate (US-A-4 434 010, US-A-5 OSg 245). The optical rr;nrirle underlying such pigments is that of the trans-mission filter. The sequence of layers making up such pigments typically includes 5 layers: a dielectric layer of low refractive index, eg. silicon dioxide, a semitransparent reflecting metal 15 layer, eg. titanium, aluminum or chromium, a dielectric layer of low refractive index, eg. silicon dioxide, a highly reflecting opaque metal layer, eg. Al ' or titanium, a dielectric layer of low refractive index, eg. silicon dioxide, a semitransparent reflecting metal layer, eg. aluminum, chromium or titanium, and a 20 dielectric layer of low refractive index., eg. silicon dioxide,_ Pigments of this type have the disadvantage that they are costly, ~ ; hl r to produce in large amounts, not stable to alkali and, what is more, usually do not h~ve the desired acid fastness.
DE-A-42 41 753, an earlier patent document which was llnrnhl;
at the priority date of the present invention, ~egrr; h~ inter-ference pigments for forgeryproof documents which include at least one rrlrrl~ss, highly refractive metal oxide layer and a 30 nonselectively Ahsrrh;ng metal and/or metal oxide or carbon layer but no reduced titanium dioxide layer.
It is an object of the present invention to provide further in-terference pigments which have advantageous properties for the 35 field of the forgeryproof marking of documents and rArk~g; ng.
We have found that this object is achieved by the use of inter-ference pigments based on titanium dioxide-coated silicatic platelets which have been heated in a reducing ~ re, in 40 combination with scattering color pigments or scattering white pigments, for preparing forgeryproof, especially difficult- or ;~ros~;hl~-to-copy, documents and pArkAg;ng.
Amended sheet ' 0050/g4900 2~ 9~ 621 In a preferred ~ho~ L of the use of the interference pig-ments, they are used in combinatlon with scattering color pig-ments which are ~ l tary in color to the reflection color of the interference pigments.
Suitable plateletlike silicatic substrates for the interference pigments to be used according to the present invention Lnclude especially light-colored or white micas, particularly preferably flakes of preferably wet-ground muscovite. It is of course also 10 possible to use other natural micas, such as phlogopite or bio-tite, artificial micas, talc and glass flakes.
The substrate particles are coated with a layer which consists essentially of titanium dioxide and may contain minor proportions 15 (< 5% by weight) of further, preferably ~l~rl~s, metal oxides such as zirconium dioxide and tin dioxide.
5uch pigments are common knowledge; cf. for example DE-A-14 67 468, DE-A-32 37 264 or DE-A-20 09 566. Titanium diox-20 ide-coated mica platelets are also commercially available unde~_ the names Iriodin~ (E. Merck, Darmstadt)~ Flonac~ (Remira Oy, Pori, Finland) or Nearlin~ (Mearl Corporation, Ossining, New York).
25 The thirkn~5 o~ the Tio2 layer determines the hue and it general-ly ranges with the desired interference color from 20 to 200 nm, preferably from 40 to 160 nm.
The interference pigments to be used according to the present in-30 vention are obtained by heating the titanium dioxide-coated sili-cate platelets in the presence of one or more reducing gases.
Suitable reducing gases include in particular hydrogen and espe-cially ammonia and also mixtures of these two gases which have 35 preferably been diluted with an inert gas.
Suitable t _ ~LUL~3 for this reducing treatment generally range from 500 to 1000-C, preferably from 600 to 800-C.
40 Depending on the reaction conditions (concentration and nature of the reducing gas, temperature, duration of the treatment) a mul-tiplicity of oxidic and/or nitridic titanium u~-d3 are ob-tained in which the titanium is in an oxidation state < 4, for example lower titanium oxides, such as Ti30s and Ti2o3, up to TiO, 45 titanium oxynitrides and even titanium nitride.
Amended sheet ' 0050/44900 2191~1 Such interference pigments and their production are known from JP-A-164 653/1983, 126 463/1984 and 184 570/1985 and also in par-ticular from DE-A-34 33 657 and EP-A-332 071.
5 Of use for the present invention are in particular those inter-ference pigments where the Tio2 layer has not been completely re-duced, ie. where titanium dioxide Ls still present alongside the reduced titanium - ~c mentioned.
10 Particular preference i3 given to pigments which, based on the Tio2 still present, have a reduced titanium compound content of from 0.1 to 50~ by weight, especially from 0.1 to 10~ by weight, ie. have only been reduced ~lightly~ or nparticularly lightly~.
15 With increasing reduction, the mass tone color of the pigments shifts toward the absorption color of the reduction products of titanium, which i8 why relatively strongly reduced pigments are suitable in particular for the blue to violet region.
20 Relatively lightly reduced pigments, in contrast, can be used tp cover the entire range of hues. The pigments obtained have a strong luster and a pastellike color and on copying they give rise to conspicuous off-shade colors.
25 In addition, the pigments of the presen~ invention are notable for light fastness.
The interference pigments to be used according to the present in-vention may additionally have a top layer of col~rl ~Sc or 30 selectively Ahs~rhi~g metal oxide. Suitable metal oxides for this layer include for example titanium oxide, zirconium oxide, tin oxide, chromium oxide, iron oxide, aluminum oxide, silicon oxide or zinc oxide or mixture~ thereof. This layer can be used to fur-ther modify the interference color of the pigment and, if colored 35 oxides are used, additionally the mass tone color, too.
Preferably, however, the interference pigments to be used have no additional top layer.
40 The interference pigments to be used according to the present in-vention preferably have an average particle diameter (based on the largest particle diameter) of from 5 to 30 ~m.
They are used in combination with scattering color pigments or 45 scattering white pigments.
Amended sheet 0050~g4900 Scattering pigments for the purposes of the present invention are pigmentary colorants which work chiefly by selective absorption or diffuse scattering. As scattering color pigments it is also po3sible to use scattering white pigments surface-colored with 5 transparent colorants.
The scattering color pigments used are preferably l~ tary in color to the reflection color of the interference pigments.
10 Suitable scattering color pigments include not only inorganic but also organic pigments having a refractive index n greater than 1.65.
Examples of inorganic pigments include iron oxides, bismuth vana-15 date, colored spinels and nickel titanium yellow.
Examples of organic pigments are monoazo pigments (ie. products -derived from acetoacetarylide derivates or from ~-naphthol deriv-atives), laked monoazo dyes, such as laked ~ hydLv~y-laphthoic acid 20 dyes, disazo pigments, fused disazo pigments, is~;nr7nl in~ deriva=
tives, derivatives of naphthalene- or perylene-tetracarboxylic acid, anthraquinone pigments, rh7~7n~7;gQ derivatives, azomethine derivatives, qll7nA~ri~7~n~c~ ~7;~A~in~c, pyrazoloqnin~l~n~c, phthalocy~nine pigments and laked basic dyes, such as laked 25 triarylmethane dyes, provided they have a refractive index n greater than 1.65. Otherwise these pigments are suitable for the surface-coloring of scattering white pigments.
Titanium dioxide in particular is a suitable scattering white 30 pigment.
The use of the interference pigments according to the present in-vention has the following advantages for visual perception.
Pirst, the pigmented marking is easy to see from every angle, 35 even against a transparent or light-colored ground, since the re-flected interference color can be seen sign;ficAntly more clearly and with much higher intensity through the coating of the present invention. Furthermore, copying, even with powerful color copi-ers, gives rise to off-shade colors.
gO
On copying for example a document marked with a violet inter-ference pigment and a scattering white pigment (eg. rutile), the interference pigment with the violet reflection color will appear yellow against the white scattering background. If the b~ckground 45 is pigmented with iron red, cobalt spinel blue or halogenated phthalocyanine instead of with titanium dioxide, the color copy will show brownish, greenish or y~ L~en off-shade colors.
Amended sheet ~ u _ 6 The same result is obtained on surface-coloring the scattering white pigment with dyes, for example paper dyes, in red, blue or yellow.
It is particularly advantageous to combine the interference pig-ments of the present invention with scattering color pigments which are ~ ary in color to the reflection color of the interference pigment_. If, for example, an interference pigment 10 having a bluish violet reflection color is used to apply a pattern atop a ground colored with a pigment that scatters yellow light, the pattern will not show up in a color copy, since it is Le~L~du~ed with a greenish yellow off-shade color.
15 The effects mentioned are particularly cnnQpi~lnn~, ie. provide the best protection against forgery, when the documents to be fvr~eLyyLo~fed are prepared with the interference pigments ending up at the very top, ie. printed atop a printed ground of scatter-ing color or white pigment, but are still noticeable - albeit not 20 as powerfully - when the interference pigment and the scatteringL
color or white pigment are mixed and then printed together.
The interference pigments of the present invention are advanta-geously applied via the step of making a printing ink and subse-25 quently applying this printing ink using conventional printingprocesses, eg. screen printing, intaglio printing, bronze print-ing, flexographic printing or offset printing.
The pigments are also with particular advantage incorporable into 30 coatings which are used for overcoating prints.
Einally, a further advantageous application is the incorporation into plastics films which, if desired, are laminated onto paper.
35 Examples Preparation and use of interference pigments according to the present invention 40 Example 1 In a ~r;c~lly rotatable single-neck quartz L~ul.d bo~om flask equipped with a gas inlet and outlet in the axis of rotation and enclosed by a rl ~ h~l 1 oven, 15 g of a TiO2-coated mica pigment 45 having a violet interference color (Iriodin~ 219 rutile pearl violet; Merck) were initially inertized for 2 h with 15 1/h of nitrogen and then heated to 700 C. Then 2 1/h of ammonia were Amended Sheet mixed into the inert gas. After 2 h the supply of ammonia was terminated and the heating was switched off. During the cooling down to room temperature, flushing with nitrogen was continued.
5 The pigment thus produced had a slightly violet color.
To convert it into a 3creen printing ink, 7.5 g of the pigment were stirred into 92.5 g of a commercial binder solution (com-position: copolymer based on vinyl chloride and vinyl isobutyl 10 ether - Laroflex~ MP 45/acetate/aliphatics).
This ink was then screen-printed using a commercial screen print-ing machine (screen mesh size 112 ~m) in a th;rkn~Qs of 45 ~m onto a resin-coated, yellow paper uniformly printed with a printing 15 ink containing bismuth vanadate, and air-dried.
The printed feature waa distinctly visible on the yellow ground even at fine lines.
20 In the color copy, the feature ~;Q-pr~A~ed; only the yellow ground was visible.
Printing the feature onto the yellow paper using the printing ink containing the unreduced starting pigment made it virtually in-25 visible, even in the original.
In addition, the feature was printed with the printing ink of thepresent invention onto resin-coated, white, TiO2-coated paper. At the luster angle, the feature appeared in the violet reflection 30 color, but away from the luster angle it had a yellowish gray tone.
A color copy leplodueed the feature in lemon yellow.
35 Example 2 Example 1 was repeated using 15 g of a TiO2-coated mica pigment with a blue interference color (Iriodin 221 rutile fine blue;
Merck), inertizing with 10 l/h of nitrogen and heating to 700 C.
40 The ~uL~e~u~nt reduction, again over two hours was carried out with a mixture of 5 l/h of nitrogen and 5 l/h of ammonia.
The pigment obtained had a pale blue color and was converted into a screen printing ink, and screen printed, as ~rQrr; h~d in Exam-45 ple 1.
Amended Sheet 8 2 1 9 1 6 2On resin-coated, white, ~iO2-coated paper, the feature had a blue reflection color at the luster angle and a yellowish gray tone away from the luster angle.
5 A color copy reproduced the feature with an intensive yellow off-shade color.
Printed onto yellow paper, the feature was distinctly visible even at fine lines, whereas it became invisible in the color 10 copy.
Amended Sheet
Use of interference pigments containing reduced titanium oxide layers for preparing forgeryproof documents and p~k~gi ng 5 The present invention relates to the use of specific interference pigments based on titanium dioxide-coated silicatic platelets which have been heated in a reducing atmosphere, in combination with scattering color pigments or scattering white pigments, for preparing forgeryproof documents and r~k~g; n7, The forgeryproofing of documents such as paper money, postage stamps, checks, tax stamps, checkcards, rail or air tickets, credit cards, t~l~ph~n~ cards, lottery tickets, share certifi-cates, gift vouchers, passes or identity cards is becoming more 15 and more important in view of the introductlon of evermore power-ful color copiers and the attendant scope for forgery. The same is true of valuable pa~kAg; ng.
Forgeryproofness has in the past been pursued in various ways.
20 For instance, the originals were marked using magnetic pigments~_ or fluorescent dyes. Eowever, these markings have the disadvan-tage that their presence is not immediately r~ogni 7~hl e visu-ally; they can only be detected using appropriate, more or less complex, reading apparatus. The same is true of marking with IR
25 or UV dyes or pigments.
Greater interest therefore pertains to marks which are suffi-ciently reliably r~o7n;7~hle with the unaided, naked eye and make it easy to distinguish the copy from the original. In prac-30 tice this kind of mark has taken the form of water marks - sil-very bright metal strips which show up black in the copy owing to the total reflection of the light - or holograms. However, the disadvantage of these marks is that they are easy to imitate or, in the case of holograms, costly and prone to damage.
The most recent addition to the ways of marking authenticity is the use of simple interference pigments. ~owever, applied atop a light-colored ground, interference pigments are virtually invis-ible, the exact field of the identifying mark iB difficult to 40 make out, and the markings are c~.,seyuently easily overlooked.
Interference pigments in the conventional sense (described for example in U5-A-3 087 827 are plateletlike luster pigments con-sisting y~ n~ntly of a mica substrate coated with a layer of 45 highly refractive material, eg. rutile, zirconium dioxide or tin dioxide, in a certain th;okn~s (generally >50 nm) to form thin platelet colors. Interference pigments have to be applied in an Amended sheet ' 0050~44900 ~ 2 oriented state. However, the intensity of the color of interference color pigments is low compared with that of scatter-ing color pigments. They have an angle-dependent reflection maxi-mum. Interference pigments of this type have for many years been 5 used in cosmetics and plastics.
There have also been ~;crlos~d multi-layer pigments which exhibit a distinct angle-de~l.dent color change and are produced by pul-verizing thin film security devices - thin multi-layer films de-10 tached from the substrate (US-A-4 434 010, US-A-5 OSg 245). The optical rr;nrirle underlying such pigments is that of the trans-mission filter. The sequence of layers making up such pigments typically includes 5 layers: a dielectric layer of low refractive index, eg. silicon dioxide, a semitransparent reflecting metal 15 layer, eg. titanium, aluminum or chromium, a dielectric layer of low refractive index, eg. silicon dioxide, a highly reflecting opaque metal layer, eg. Al ' or titanium, a dielectric layer of low refractive index, eg. silicon dioxide, a semitransparent reflecting metal layer, eg. aluminum, chromium or titanium, and a 20 dielectric layer of low refractive index., eg. silicon dioxide,_ Pigments of this type have the disadvantage that they are costly, ~ ; hl r to produce in large amounts, not stable to alkali and, what is more, usually do not h~ve the desired acid fastness.
DE-A-42 41 753, an earlier patent document which was llnrnhl;
at the priority date of the present invention, ~egrr; h~ inter-ference pigments for forgeryproof documents which include at least one rrlrrl~ss, highly refractive metal oxide layer and a 30 nonselectively Ahsrrh;ng metal and/or metal oxide or carbon layer but no reduced titanium dioxide layer.
It is an object of the present invention to provide further in-terference pigments which have advantageous properties for the 35 field of the forgeryproof marking of documents and rArk~g; ng.
We have found that this object is achieved by the use of inter-ference pigments based on titanium dioxide-coated silicatic platelets which have been heated in a reducing ~ re, in 40 combination with scattering color pigments or scattering white pigments, for preparing forgeryproof, especially difficult- or ;~ros~;hl~-to-copy, documents and pArkAg;ng.
Amended sheet ' 0050/g4900 2~ 9~ 621 In a preferred ~ho~ L of the use of the interference pig-ments, they are used in combinatlon with scattering color pig-ments which are ~ l tary in color to the reflection color of the interference pigments.
Suitable plateletlike silicatic substrates for the interference pigments to be used according to the present invention Lnclude especially light-colored or white micas, particularly preferably flakes of preferably wet-ground muscovite. It is of course also 10 possible to use other natural micas, such as phlogopite or bio-tite, artificial micas, talc and glass flakes.
The substrate particles are coated with a layer which consists essentially of titanium dioxide and may contain minor proportions 15 (< 5% by weight) of further, preferably ~l~rl~s, metal oxides such as zirconium dioxide and tin dioxide.
5uch pigments are common knowledge; cf. for example DE-A-14 67 468, DE-A-32 37 264 or DE-A-20 09 566. Titanium diox-20 ide-coated mica platelets are also commercially available unde~_ the names Iriodin~ (E. Merck, Darmstadt)~ Flonac~ (Remira Oy, Pori, Finland) or Nearlin~ (Mearl Corporation, Ossining, New York).
25 The thirkn~5 o~ the Tio2 layer determines the hue and it general-ly ranges with the desired interference color from 20 to 200 nm, preferably from 40 to 160 nm.
The interference pigments to be used according to the present in-30 vention are obtained by heating the titanium dioxide-coated sili-cate platelets in the presence of one or more reducing gases.
Suitable reducing gases include in particular hydrogen and espe-cially ammonia and also mixtures of these two gases which have 35 preferably been diluted with an inert gas.
Suitable t _ ~LUL~3 for this reducing treatment generally range from 500 to 1000-C, preferably from 600 to 800-C.
40 Depending on the reaction conditions (concentration and nature of the reducing gas, temperature, duration of the treatment) a mul-tiplicity of oxidic and/or nitridic titanium u~-d3 are ob-tained in which the titanium is in an oxidation state < 4, for example lower titanium oxides, such as Ti30s and Ti2o3, up to TiO, 45 titanium oxynitrides and even titanium nitride.
Amended sheet ' 0050/44900 2191~1 Such interference pigments and their production are known from JP-A-164 653/1983, 126 463/1984 and 184 570/1985 and also in par-ticular from DE-A-34 33 657 and EP-A-332 071.
5 Of use for the present invention are in particular those inter-ference pigments where the Tio2 layer has not been completely re-duced, ie. where titanium dioxide Ls still present alongside the reduced titanium - ~c mentioned.
10 Particular preference i3 given to pigments which, based on the Tio2 still present, have a reduced titanium compound content of from 0.1 to 50~ by weight, especially from 0.1 to 10~ by weight, ie. have only been reduced ~lightly~ or nparticularly lightly~.
15 With increasing reduction, the mass tone color of the pigments shifts toward the absorption color of the reduction products of titanium, which i8 why relatively strongly reduced pigments are suitable in particular for the blue to violet region.
20 Relatively lightly reduced pigments, in contrast, can be used tp cover the entire range of hues. The pigments obtained have a strong luster and a pastellike color and on copying they give rise to conspicuous off-shade colors.
25 In addition, the pigments of the presen~ invention are notable for light fastness.
The interference pigments to be used according to the present in-vention may additionally have a top layer of col~rl ~Sc or 30 selectively Ahs~rhi~g metal oxide. Suitable metal oxides for this layer include for example titanium oxide, zirconium oxide, tin oxide, chromium oxide, iron oxide, aluminum oxide, silicon oxide or zinc oxide or mixture~ thereof. This layer can be used to fur-ther modify the interference color of the pigment and, if colored 35 oxides are used, additionally the mass tone color, too.
Preferably, however, the interference pigments to be used have no additional top layer.
40 The interference pigments to be used according to the present in-vention preferably have an average particle diameter (based on the largest particle diameter) of from 5 to 30 ~m.
They are used in combination with scattering color pigments or 45 scattering white pigments.
Amended sheet 0050~g4900 Scattering pigments for the purposes of the present invention are pigmentary colorants which work chiefly by selective absorption or diffuse scattering. As scattering color pigments it is also po3sible to use scattering white pigments surface-colored with 5 transparent colorants.
The scattering color pigments used are preferably l~ tary in color to the reflection color of the interference pigments.
10 Suitable scattering color pigments include not only inorganic but also organic pigments having a refractive index n greater than 1.65.
Examples of inorganic pigments include iron oxides, bismuth vana-15 date, colored spinels and nickel titanium yellow.
Examples of organic pigments are monoazo pigments (ie. products -derived from acetoacetarylide derivates or from ~-naphthol deriv-atives), laked monoazo dyes, such as laked ~ hydLv~y-laphthoic acid 20 dyes, disazo pigments, fused disazo pigments, is~;nr7nl in~ deriva=
tives, derivatives of naphthalene- or perylene-tetracarboxylic acid, anthraquinone pigments, rh7~7n~7;gQ derivatives, azomethine derivatives, qll7nA~ri~7~n~c~ ~7;~A~in~c, pyrazoloqnin~l~n~c, phthalocy~nine pigments and laked basic dyes, such as laked 25 triarylmethane dyes, provided they have a refractive index n greater than 1.65. Otherwise these pigments are suitable for the surface-coloring of scattering white pigments.
Titanium dioxide in particular is a suitable scattering white 30 pigment.
The use of the interference pigments according to the present in-vention has the following advantages for visual perception.
Pirst, the pigmented marking is easy to see from every angle, 35 even against a transparent or light-colored ground, since the re-flected interference color can be seen sign;ficAntly more clearly and with much higher intensity through the coating of the present invention. Furthermore, copying, even with powerful color copi-ers, gives rise to off-shade colors.
gO
On copying for example a document marked with a violet inter-ference pigment and a scattering white pigment (eg. rutile), the interference pigment with the violet reflection color will appear yellow against the white scattering background. If the b~ckground 45 is pigmented with iron red, cobalt spinel blue or halogenated phthalocyanine instead of with titanium dioxide, the color copy will show brownish, greenish or y~ L~en off-shade colors.
Amended sheet ~ u _ 6 The same result is obtained on surface-coloring the scattering white pigment with dyes, for example paper dyes, in red, blue or yellow.
It is particularly advantageous to combine the interference pig-ments of the present invention with scattering color pigments which are ~ ary in color to the reflection color of the interference pigment_. If, for example, an interference pigment 10 having a bluish violet reflection color is used to apply a pattern atop a ground colored with a pigment that scatters yellow light, the pattern will not show up in a color copy, since it is Le~L~du~ed with a greenish yellow off-shade color.
15 The effects mentioned are particularly cnnQpi~lnn~, ie. provide the best protection against forgery, when the documents to be fvr~eLyyLo~fed are prepared with the interference pigments ending up at the very top, ie. printed atop a printed ground of scatter-ing color or white pigment, but are still noticeable - albeit not 20 as powerfully - when the interference pigment and the scatteringL
color or white pigment are mixed and then printed together.
The interference pigments of the present invention are advanta-geously applied via the step of making a printing ink and subse-25 quently applying this printing ink using conventional printingprocesses, eg. screen printing, intaglio printing, bronze print-ing, flexographic printing or offset printing.
The pigments are also with particular advantage incorporable into 30 coatings which are used for overcoating prints.
Einally, a further advantageous application is the incorporation into plastics films which, if desired, are laminated onto paper.
35 Examples Preparation and use of interference pigments according to the present invention 40 Example 1 In a ~r;c~lly rotatable single-neck quartz L~ul.d bo~om flask equipped with a gas inlet and outlet in the axis of rotation and enclosed by a rl ~ h~l 1 oven, 15 g of a TiO2-coated mica pigment 45 having a violet interference color (Iriodin~ 219 rutile pearl violet; Merck) were initially inertized for 2 h with 15 1/h of nitrogen and then heated to 700 C. Then 2 1/h of ammonia were Amended Sheet mixed into the inert gas. After 2 h the supply of ammonia was terminated and the heating was switched off. During the cooling down to room temperature, flushing with nitrogen was continued.
5 The pigment thus produced had a slightly violet color.
To convert it into a 3creen printing ink, 7.5 g of the pigment were stirred into 92.5 g of a commercial binder solution (com-position: copolymer based on vinyl chloride and vinyl isobutyl 10 ether - Laroflex~ MP 45/acetate/aliphatics).
This ink was then screen-printed using a commercial screen print-ing machine (screen mesh size 112 ~m) in a th;rkn~Qs of 45 ~m onto a resin-coated, yellow paper uniformly printed with a printing 15 ink containing bismuth vanadate, and air-dried.
The printed feature waa distinctly visible on the yellow ground even at fine lines.
20 In the color copy, the feature ~;Q-pr~A~ed; only the yellow ground was visible.
Printing the feature onto the yellow paper using the printing ink containing the unreduced starting pigment made it virtually in-25 visible, even in the original.
In addition, the feature was printed with the printing ink of thepresent invention onto resin-coated, white, TiO2-coated paper. At the luster angle, the feature appeared in the violet reflection 30 color, but away from the luster angle it had a yellowish gray tone.
A color copy leplodueed the feature in lemon yellow.
35 Example 2 Example 1 was repeated using 15 g of a TiO2-coated mica pigment with a blue interference color (Iriodin 221 rutile fine blue;
Merck), inertizing with 10 l/h of nitrogen and heating to 700 C.
40 The ~uL~e~u~nt reduction, again over two hours was carried out with a mixture of 5 l/h of nitrogen and 5 l/h of ammonia.
The pigment obtained had a pale blue color and was converted into a screen printing ink, and screen printed, as ~rQrr; h~d in Exam-45 ple 1.
Amended Sheet 8 2 1 9 1 6 2On resin-coated, white, ~iO2-coated paper, the feature had a blue reflection color at the luster angle and a yellowish gray tone away from the luster angle.
5 A color copy reproduced the feature with an intensive yellow off-shade color.
Printed onto yellow paper, the feature was distinctly visible even at fine lines, whereas it became invisible in the color 10 copy.
Amended Sheet
Claims (4)
1. The use of interference pigments based on titanium dioxide-coated silicatic platelets which have been heated in a reducing atmosphere, in combination with scattering color pigments or with scattering white pigments, for preparing forgeryproof documents and packaging.
2. A use as claimed in claim 1 wherefor the titanium dioxide-coated silicatic platelets have been heated in the presence of ammonia and/or hydrogen.
3. A use as claimed in claim 1 or 2 wherefor the titanium dioxide-coated silicatic platelets have been heated to from 500 to 1000° C.
4. A use as claimed in any of claims 1 to 3 wherefor the scattering color pigments are complementary in color to the reflection color of the interference pigments.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE4419089A DE4419089A1 (en) | 1994-06-01 | 1994-06-01 | Interference pigments used for security documents and packaging |
| DEP4419089.1 | 1994-06-01 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2191621A1 true CA2191621A1 (en) | 1995-12-07 |
Family
ID=6519477
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002191621A Abandoned CA2191621A1 (en) | 1994-06-01 | 1995-05-17 | Use of reduced interference pigments in producing forgery-proof security documents |
Country Status (10)
| Country | Link |
|---|---|
| US (1) | US5693135A (en) |
| EP (1) | EP0763074B1 (en) |
| JP (1) | JPH10502949A (en) |
| AT (1) | ATE159974T1 (en) |
| CA (1) | CA2191621A1 (en) |
| DE (2) | DE4419089A1 (en) |
| ES (1) | ES2108582T3 (en) |
| FI (1) | FI964780A (en) |
| TW (1) | TW316281B (en) |
| WO (1) | WO1995033009A1 (en) |
Families Citing this family (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE69312720T3 (en) * | 1993-12-10 | 2003-11-27 | Agfa Gevaert Nv | Security document with a clear or translucent support and with interference pigments contained therein |
| EP0927749B1 (en) * | 1997-12-29 | 2003-02-26 | Sicpa Holding S.A. | Coating composition, use of particles, method for tagging and identifying a security document comprising said coating composition |
| FR2782470B1 (en) * | 1998-08-19 | 2000-11-10 | Imprimerie Nationale | METHOD OF PRINTING A MEDIUM PREDICTING TO CONTROL ITS AUTHENTICITY |
| DE19928060A1 (en) * | 1999-06-15 | 2000-12-21 | Whd Elektron Prueftech Gmbh | Optically variable security feature and process for its manufacture |
| FI116086B (en) * | 2000-06-08 | 2005-09-15 | Avantone Oy | Check-marked paper or cardboard product and check-marked packaging |
| DE10051062A1 (en) * | 2000-10-14 | 2002-04-18 | Merck Patent Gmbh | Interference pigments for security uses have alternating high and low refractive index metal oxide layers wet deposited on a transparent carrier and give novel three-tone effects |
| DE10111116A1 (en) * | 2001-03-08 | 2002-09-19 | Giesecke & Devrient Gmbh | value document |
| DE10124221A1 (en) * | 2001-05-18 | 2002-11-21 | Giesecke & Devrient Gmbh | Document with security element, e.g. banknote, share, loan or diploma, has print of colored ink with visible, unprinted negative contours and overprint of metallic ink forming translucent unbroken area |
| JP4120965B2 (en) * | 2002-05-31 | 2008-07-16 | 共同印刷株式会社 | Anti-counterfeit ink and anti-counterfeit printed matter |
| US7014700B2 (en) * | 2004-01-13 | 2006-03-21 | Engelhard Corporation | Highly reflective interference pigments with dark absorption color |
| EP1844945A1 (en) * | 2006-04-13 | 2007-10-17 | M-real Oyj | Process of applying interference pigments onto a substrate |
| JP2010185073A (en) * | 2009-01-13 | 2010-08-26 | Ako Kasei Co Ltd | Dichroism pigment which has vivid appearance color and interference color |
| RU2656492C2 (en) * | 2013-06-17 | 2018-06-05 | Мерк Патент Гмбх | Transparent, optically variable interference pigments with electrical semi-conducting properties |
| US9850384B2 (en) | 2013-06-17 | 2017-12-26 | Merck Patent Gmbh | Transparent, electrically semiconducting interference TiOx pigments with high color strength |
Family Cites Families (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1165182B (en) * | 1961-06-28 | 1964-03-12 | Du Pont | Pigment based on translucent mica-like flakes and process for its manufacture |
| FR2429292A1 (en) * | 1978-06-19 | 1980-01-18 | Arjomari Prioux | Security paper contg. iridescent cpd - pref. mother of pearl, lead salt or mica; preventing reproduction by colour photocopying |
| US5059245A (en) * | 1979-12-28 | 1991-10-22 | Flex Products, Inc. | Ink incorporating optically variable thin film flakes |
| US4434010A (en) * | 1979-12-28 | 1984-02-28 | Optical Coating Laboratory, Inc. | Article and method for forming thin film flakes and coatings |
| JPS58164653A (en) * | 1982-03-26 | 1983-09-29 | Mitsubishi Metal Corp | Production of dark iridescent pigment |
| JPS59126468A (en) * | 1983-01-11 | 1984-07-21 | Shiseido Co Ltd | Pigment composed of mica and titanium |
| US4623396A (en) * | 1983-09-14 | 1986-11-18 | Shiseido Company Ltd. | Titanium-mica composite material |
| JPH0781093B2 (en) * | 1984-03-05 | 1995-08-30 | 株式会社資生堂 | Mica coated with titanium compound |
| DE3808070A1 (en) * | 1988-03-11 | 1989-09-21 | Basf Ag | METHOD FOR PRODUCING PARTICULARLY BLUE-TONE PEARL PIGMENTS |
| NL8901256A (en) * | 1989-05-19 | 1990-12-17 | Enschede & Zonen Grafisch | Document e.g. banknote mfg. process - using one or more protective layers of iridescent pigment |
| ATE119957T1 (en) * | 1990-12-12 | 1995-04-15 | Sihl Zuercher Papierfabrik An | SECURITY PAPER FOR BANKNOTES OR THE LIKE. AND METHOD FOR PRODUCING IT. |
| FR2670812B1 (en) * | 1990-12-21 | 1996-06-21 | Arjomari Europ | PRINTABLE SHEET FOR MANUFACTURING SECURITY DOCUMENTS COMPRISING AN AGAINST COUNTERFEITING OR AUTHENTICATION. |
| CZ232294A3 (en) * | 1992-03-26 | 1995-01-18 | Merck Patent Gmbh | Plate-like colored pigment and process for preparing thereof |
| DE4217511A1 (en) * | 1992-05-27 | 1993-12-02 | Basf Ag | Gloss pigments based on multi-coated platelet-shaped metallic substrates |
| DE4241753A1 (en) * | 1992-12-11 | 1994-06-16 | Basf Ag | Use of interference pigments to produce counterfeit-proof securities |
-
1994
- 1994-06-01 DE DE4419089A patent/DE4419089A1/en not_active Withdrawn
-
1995
- 1995-05-17 US US08/737,922 patent/US5693135A/en not_active Expired - Fee Related
- 1995-05-17 ES ES95920053T patent/ES2108582T3/en not_active Expired - Lifetime
- 1995-05-17 DE DE59500957T patent/DE59500957D1/en not_active Expired - Lifetime
- 1995-05-17 AT AT95920053T patent/ATE159974T1/en not_active IP Right Cessation
- 1995-05-17 EP EP95920053A patent/EP0763074B1/en not_active Expired - Lifetime
- 1995-05-17 JP JP8500236A patent/JPH10502949A/en active Pending
- 1995-05-17 CA CA002191621A patent/CA2191621A1/en not_active Abandoned
- 1995-05-17 WO PCT/EP1995/001871 patent/WO1995033009A1/en active IP Right Grant
- 1995-05-22 TW TW084105109A patent/TW316281B/zh active
-
1996
- 1996-11-29 FI FI964780A patent/FI964780A/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| US5693135A (en) | 1997-12-02 |
| FI964780A0 (en) | 1996-11-29 |
| TW316281B (en) | 1997-09-21 |
| EP0763074A1 (en) | 1997-03-19 |
| FI964780A (en) | 1996-11-29 |
| DE59500957D1 (en) | 1997-12-11 |
| JPH10502949A (en) | 1998-03-17 |
| ES2108582T3 (en) | 1997-12-16 |
| DE4419089A1 (en) | 1995-12-07 |
| EP0763074B1 (en) | 1997-11-05 |
| WO1995033009A1 (en) | 1995-12-07 |
| ATE159974T1 (en) | 1997-11-15 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |