RU2581882C1 - Marking composition and method of marking and identifying valuable document - Google Patents

Abstract

FIELD: information security.

SUBSTANCE: invention relates to means of protection of documents from forgery, and concerns a marking composition and method of labelling and identifying a valuable document. Composition contains at least one compound of rare-earth metal, a masking substance and an inert carrier. Method of labelling and identifying a valuable document is based on chemical compounds incorporated in said composition, which as a result of reaction with special indicator reagent forms a specific chelate complex, which has no luminescence when excited by UV radiation at room temperature, but reversibly exhibits luminescence at cooling-freezing temperature, which disappears when heated.

EFFECT: marking composition contains at least one compound of rare-earth metal that forms a chelate complex, to identify demanding special conditions, which considerably increases level of protection of valuable document and makes it impossible, challenging and/or unprofitable its forgery.

21 cl, 7 ex

Description

The invention relates to a method for marking a valuable document with a marking composition for protection against counterfeiting based on compounds forming chelate complexes, and a method for identifying a valuable document using a special indicator reagent. The invention also relates to a marking composition that contains at least one rare earth metal compound, a masking agent and an inert carrier.

The chelate complexes of rare-earth metals (REM) and marking materials based on REM compounds with luminescent properties are widely known, which are successfully used to protect against counterfeiting of securities and documents due to the characteristic narrow-band luminescence spectra.

From the patent US 4572803 A, 02.25.1986 it is known about the use of salts of rare earth metals luminescent under UV radiation in various fields of technology.

Compounds are known that are described in US Pat. No. 7,767,315 B2, August 3, 2010, which are proposed for creating marking materials for securities and documents by incorporating REM-based organometallic complexes luminescent under UV radiation into toner or paper.

EP 1371652 A4, March 30, 2005 describes luminescent europium complexes and water-based paint compositions containing europium complexes. These compositions, colorless in daylight, have bright red luminescence under UV radiation.

In the patent EP 0446846 B1, 08/17/1994 a composition for thermal transfer printing is proposed, one of the components of which is a complex of rare-earth europium metal with organic ligands, which shows intense red luminescence in the visible range when excited by UV radiation (366 nm), which is dispersed in a polymer binder .

However, given the increased technical level of counterfeiters, these marking materials can be easily identified by them and imitated or tampered with.

Marking materials based on the use of rare-earth metal compounds described in patents US 7198732 B2, 04/03/2007, US 7399434 B2, 07/15/2008, US 4833311 A, 05/23/1989, US 4921280 A, 01.05 are more difficult to identify and counterfeit. 1990 and US 5118349 A, 06/02/1992. These patents describe compounds of rare earth metals that are capable of changing the intensity of a characteristic luminescence band under UV radiation when cooled to a temperature of from minus 20 ° C to minus 269 ° C. These patents also describe the use of such compounds to create marking materials for the protection of valuable documents.

Despite all the advantages of such marking materials, the described luminescent compounds have insufficient thermal and photo stability.

Known methods of chemical protection of valuable documents, which are based on the introduction of protective chemical reagents (ZHR) in paper (FR 2694772 A1, 02/18/1994), in paint (DE 10020873 A1, 11/08/2001) or simultaneously in paper and ink (RU 2260088 C2 09/10/2005). Authentication in this case is carried out by color and color intensity of the products of the reaction of ZHR with a specific colorimetric indicator.

The use of dyes that change their color as a result of exposure to acids, bases, organic solvents or chemical reagents is not preferable for the protection of valuable documents, since these indicator reactions are widely known, including to counterfeiters, or methods of protection are quite difficult to implement.

The closest analogue is the method of marking documents and materials providing such marking, described in patent US 4736425 A, 04/05/1988. This patent describes a method by which any part of a chelated fluorescent complex, which is a marking material, is introduced into a valuable document in some way. Then, to verify the authenticity of the document, the missing part of the chelated fluorescent complex as part of the indicator reagent is introduced into the checked (marked) document, as a result of which the chelated fluorescent complex is synthesized. To eliminate the traces of the authentication of a valuable document (fluorescence), it is proposed that an acid or base be applied to the fluorescent zone of the verified (identified) material.

The disadvantage of the described method and marking material is the insufficient degree of protection of the valuable document from the identification of the marking substance and, accordingly, its falsification. Another drawback is the need to use additional chemical reagents (acids or bases) to eliminate the fluorescence of chelate complexes, since a valuable document may contain acid-base indicators, which are often used to create elements of protection against deletion (etching) or to replace entered information. In addition, the described method does not allow to produce a valuable document containing locally located security elements, which after exposure to the indicator reagent on the valuable document have the form of individual points.

The technical problem solved by the present invention is the creation of a new, with a higher degree of protection and universal in application, method of marking and identification of a valuable document and marking composition.

The technical result achieved by the implementation of the present invention is to increase the degree of security of valuable documents through the use of marking compositions, the detection, identification and reproduction of which is a technologically challenging task.

To solve this problem, it was proposed to use a marking composition based on compounds forming chelate complexes after exposure to an indicator reagent, which do not luminesce at room temperature, but luminesce upon cooling to a negative temperature. To solve the problem proposed objects and preferred embodiments of the invention indicated in the dependent claims.

This technical solution relates to expert security features and can be implemented by authenticating valuable documents with specialists who have at their disposal special equipment, special indicator reagents and materials.

The invention relates to a method for protecting valuable documents protected from forgery, such as letterhead securities, banknotes, identification cards, passports, driver's licenses, excise stamps, postage stamps, special protected labels, plastic cards, etc.

The term "marking composition" in the description is used to mean a simple mixture of individual chemical compounds and / or physically and / or chemically related chemical compounds and materials that have special properties that make it possible to identify a valuable document and make it impossible, difficult and / or economically unprofitable his fake.

The claimed method for marking and identifying a valuable document is based on chemical compounds, which, as a result of interaction with a special indicator reagent, form a specific chelate complex that does not have luminescence when excited by UV radiation (365 nm) at room temperature (20-25 ° C), however, it reversibly exhibits luminescence upon cooling to a negative temperature (below minus 1 ° C), which disappears upon heating. The chemical compound that forms the chelate complex and which is part of the marking composition does not luminesce at room temperature even after treatment with an indicator reagent. For its identification, special conditions are necessary, which significantly increases the level of protection of a valuable document. Thus, there is no need for additional processing of the luminescent portion of the valuable document with acid or base to eliminate luminescence after checking the authenticity of the product.

The marking composition for marking a valuable document protected from falsification according to the method described above is a composition of at least one rare earth metal compound (1-20 wt.%), A masking agent (1-20 wt.%) And an inert carrier insoluble in water (60-98 wt.%).

REM compounds can be ordinary or double salts (TbCl ₃ , SmCl ₃ , Tb (NO ₃ ) ₃ TbLa (CO ₃ ) ₃ , etc.) or complexes of REM with organic ligands (8-hydroxyquinoline, dibenzoylmethane, etc.), which should be selected in such a way as not to show noticeable luminescence in the quantities used in the manufacture of a valuable document, however, to form a chelate complex with an indicator reagent reversibly showing luminescence upon cooling.

The use of a composition containing an inert carrier allows one to produce a valuable document containing locally located particles with an average size of 1-1000 μm, which, after exposure to an indicator reagent on a valuable document, reversibly exhibit characteristic luminescence. The use of an inert carrier also reduces the consumption of rare earth metal compounds for marking valuable documents. As carriers, sorbent materials (porous or having a large surface area, for example silica gel or Al ₂ O ₃ , etc.) can be used; acrylate hydrogels having a three-dimensional network structure, and polymer microfibers, for example polyamide.

The masking substance contained in the composition for marking a valuable document is necessary to mask possible weak luminescence of an inert carrier or to pre-position the particles of the marking composition in a valuable document before or after exposure to an indicator reagent. Organic phosphors and dyes can be used as a masking agent (Orlum yellow-green 490T, Orlum white 520T, Orlum white 540T, Orlum white 612TM, Hostasol Red GG, PV Fast Blue BG, Uvitex NFW Liquid, Uvitex OB, Eu (tta ) ₃ , Eu (tta) ₃ Phen, Sm (tta) ₃ , etc.), as well as inorganic phosphors (Ф (а) СД-546-1 based on La ₂ O ₂ S: Er, Yb; Ф (а) SD-660-3 based on YOCl: Er, Yb, etc.), including anti-Stokes phosphors (FAM-810 / 1000-1 based on Y ₂ O ₂ S: Er, etc.) and phosphors based on semiconductor nanocrystals ( GaN, CdSe, ZnSe, etc.), as well as salts of rare-earth metals that do not form chelate complexes, reversibly showing th luminescence under cooling (EuCl _3, SmCl _3). The masking substance or chemical elements that make up it do not react with the indicator reagent to form a chelate complex that reversibly exhibits luminescence upon cooling.

The composition of the indicator reagent is a solution of a carboxylic acid and / or β-diketone (acetylacetone, etc.) and / or a salt of a carboxylic acid in alcohol (methanol, ethanol, propanol, isopropanol, etc.), which must be selected so as to provide reliable identification of security features. As carboxylic acids, can be used isonicotinic, 3-hydroxy-isonicotinic, 1-hydroxy-2-naphthoic, 2-hydroxy-4-quinolinecarboxylic, salicylic acids, etc. The mass fraction of compounds dissolved in alcohol (carboxylic acids and / or salts , and / or β-diketones) in the indicator reagent preferably does not exceed 1%.

In particular cases of implementing the invention, the compounds of rare-earth metals and a masking substance can be both soluble in water and / or organic solvents, and insoluble, depending on the method of their introduction into a valuable document.

In particular cases of the invention, depending on the method of marking a valuable document, the manifestation or color change of luminescence during cooling may take the form of individual dots or spots on the surface of the valuable document.

In particular cases of the invention, the marking composition is included in a valuable document at the stage of its manufacture or in a valuable document already manufactured

The following are examples of the implementation of the invention.

Example 1

Preparation of the composition: 5 g of silica gel with an average particle size of 10 μm were sequentially saturated with 1 ml of a 5% aqueous solution of TbCl ₃ and 1 ml of a 5% solution of ORLUM 560 phosphor in chloroform. The resulting composition was introduced into a suspension of paper pulp in an amount of 3% by weight of absolutely dry (hereinafter - as) fiber. Then the resulting slurry of the pulp was used to produce a valuable document protected from forgery. The particles of the composition in the paper of the valuable document produced did not have a color when exposed to daylight, but they were luminescent upon excitation with UV radiation in yellow-orange color and had a luminescence spectrum characteristic of the ORLUM 560 phosphor. The obtained valuable document was treated with indicator reagent (1% alcohol solution of 3-hydroxy-isonicotinic acid). In the processing area of a valuable document under UV radiation (365 nm), the particles of the composition at room temperature (20-25 ° C) were luminescent in yellow-orange color, however, when cooled to a temperature of minus 196 ° C, the luminescence color reversibly changed to green. Moreover, the luminescence bands characteristic of Tb compounds reversibly appeared in the luminescence spectrum.

Example 2

Preparation of the composition: 5 g of silica gel with an average particle size of 100 μm were successively saturated with 1 ml of a 5% aqueous solution of EuCl ₃ and 1 ml of a 5% aqueous solution of TbCl ₃ and GdCl ₃ (in a 1: 1 molar ratio). The learned composition was added to a suspension of paper pulp in an amount of 3% by weight of A.S. fiber. Then the resulting slurry of the pulp was used to produce a valuable document protected from forgery. The particles of the composition in the paper of the valuable document produced did not have color when illuminated by daylight and did not luminesce when excited by UV radiation. The obtained valuable document was treated with indicator reagent (1% alcohol solution of 2-hydroxy-4-quinolinecarboxylic acid). In the processing area of a valuable document under UV radiation (365 nm), the particles of the composition at room temperature (20-25 ° C) were luminescent in red, but when cooled to minus 196 ° C, the color of the luminescence reversibly changed to green. Moreover, the luminescence bands characteristic of Tb compounds reversibly appeared in the luminescence spectrum.

Example 3

Preparation of the composition: in an aqueous solution containing the starting components for the production of an acrylate hydrogel (acrylamide, methylene bis acrylamide, ammonium persulfate and tetramethylethylenediamine), a suspension of phosphor FAM-810 / 1000-1 and a chemically precipitated double salt of TbLa (CO ₃ ) _{3 were} added in the amount of 5% and 3%, respectively, of the final mass of the hydrogel. After completion of the hydrogel polymerization reaction, the resulting mass was ground in water to obtain particles up to 1000 microns in size. The resulting suspension of a hydrogel containing FAM-810 / 1000-1 and TbLa (СО ₃ ) ₃ was mixed with paper pulp (concentration of a.a. fiber of 0.2%) and introduced into the paper locally, onto areas of a wet paper web, using devices for zonal (in the form of a strip) introduction installed in the low tide zone of the round-mesh PM. After drying the paper on the drying part of the paper machine, it was used to produce a valuable document protected from forgery. The particles of the composition in the valuable document paper did not have color when illuminated by daylight, but they were luminescent when excited by infrared radiation (1.5-1.6 μm) in the region of 0.8-1.0 μm and had the characteristic FAM-810 phosphor / 1000-1 luminescence spectrum. The valuable document produced was processed with an indicator reagent (1% alcohol solution of acetylacetone and salicylic acid sodium salt in a 1: 1 molar ratio). In the processing area of a valuable document under UV radiation (365 nm), the particles of the composition at room temperature (20-25 ° C) were luminescent in red, but when cooled to a temperature of minus 78.5 ° C, green luminescence reversibly showed. Moreover, the luminescence bands characteristic of Tb compounds reversibly appeared in the luminescence spectrum.

Example 4

Preparation of the composition: 5 g of polyamide fibers (diameter 50-60 μm, length 2-5 mm) were added to 100 ml of an aqueous-alcoholic solution containing 0.5 g TbCl ₃ and 0.05 g Eu (tta) ₃ . The resulting mixture was autoclaved to 65 ° C and held for 120 minutes. Then the autoclave was cooled at a rate of 0.5 ° C / min to room temperature. The polyamide fibers thus treated were washed with water, dried, and introduced into a suspension of paper pulp in an amount of 0.01% by weight of a.s. fiber. The resulting slurry of paper pulp was used to make a valuable document protected from falsification. Particles of the composition (carrier — polyamide fibers) in the paper of a valuable document produced did not have color when exposed to daylight, but they were luminescent when excited by red UV radiation and had a luminescence spectrum characteristic of Eu compounds. The obtained valuable document was treated with indicator reagent (1% alcohol solution of 3-hydroxy-isonicotinic acid). In the processing area of a valuable document under UV radiation (365 nm), polyamide fibers were luminescent in red at room temperature (20-25 ° C), but when cooled to a temperature of minus 196 ° C, the luminescence color reversibly changed to green. Moreover, the luminescence bands characteristic of Tb compounds reversibly appeared in the luminescence spectrum.

Example 5

Preparation of the composition: 5 g of the product obtained by chemical precipitation of Sm ₂ (CO ₃ ) ₃ on the surface of Al ₂ O ₃ was impregnated with 10 ml of a 5% solution of PV Fast Blue BG dye. The resulting composition was applied to flexographic UV curing varnish in an amount of 1% by weight of the latter. Then this paint was used to make a valuable document protected from falsification. In the paint layer, mounted on the surface of the valuable document produced, under bright daylight, bright blue dots were observed that were not luminescent when excited by UV radiation. After processing the color layer of a valuable document with an indicator reagent (1% alcohol solution of 1-hydroxy-2-naphthoic acid) in the treatment zone under UV radiation (365 nm) at room temperature (20-25 ° C), luminescence was not observed, however upon cooling to a temperature of minus 196 ° C, red luminescence reversibly appeared. In this case, the luminescence bands characteristic of Sm compounds reversibly appeared in the luminescence spectrum.

Example 6

Preparation of the composition: 5 g of the product obtained by chemical precipitation of Sm ₂ (CO ₃ ) ₃ on the surface of Al ₂ O ₃ was impregnated with 10 ml of a 1% colloidal solution of CdSe. This composition was added to the surface sizing paper in an amount of 3% by weight of the composition. Then this composition was used to produce a valuable document protected from falsification. Thus obtained, a sizing layer on the surface of a valuable document paper had a yellowish tint when exposed to daylight and luminesced yellow when excited by UV radiation and had a luminescence spectrum characteristic of colloidal CdSe. After processing a valuable document with an indicator reagent (1% alcohol solution of 1-hydroxy-2-naphthoic acid) in the treatment zone under UV radiation (365 nm) at room temperature (20-25 ° C), the CdSe luminescence disappeared, but when cooled up to a temperature of minus 196 ° С red luminescence was reversibly manifested. In this case, the luminescence bands characteristic of Sm compounds reversibly appeared in the luminescence spectrum.

Example 7

Preparation of the composition: 5 g of silica gel with an average particle size of 100 μm were successively impregnated with 2 ml of a 2% solution of the complex of terbium with dibenzoylmethane Tb (dbm) ₃ and dye Hostasol Red GG in chloroform in a 1: 1 molar ratio. The resulting composition was introduced into a suspension of paper pulp in an amount of 3% by weight of A.S. fiber. Then the resulting slurry of the pulp was used to produce a valuable document protected from forgery. The particles of the composition in the paper of the valuable document produced did not have a color when exposed to daylight, but they were luminescent when excited by UV radiation in red and had a luminescence spectrum characteristic of the Hostasol Red GG phosphor. The obtained valuable document was treated with an indicator reagent (1% alcohol solution of 3-hydroxy-isonicotinic acid and acetylacetone in a 1: 1 molar ratio). In the processing area of a valuable document under UV radiation (365 nm), the particles of the composition at room temperature (20-25 ° C) were luminescent in red, but when cooled to minus 196 ° C, the color of the luminescence reversibly changed to green. Moreover, the luminescence bands characteristic of Tb compounds reversibly appeared in the luminescence spectrum.

Claims (21)

1. A marking composition for protection against counterfeiting a valuable document, which is a composition of at least one rare earth metal compound capable of forming a chelate complex as a result of a reaction with an indicator reagent that does not luminesce at room temperature under the influence of UV radiation, but reversibly exhibits luminescence when cooling to a negative temperature, a masking agent and an inert carrier, insoluble in water, in the following ratio of components, wt.%:
Rare earth compound 1-20 Masking agent 1-20 Inert carrier 60-98 2. The marking composition according to claim 1, characterized in that the composition is colorless or slightly colored. 3. The marking composition according to claim 1, characterized in that the composition does not luminesce or has weak luminescence. 4. The marking composition according to claim 1, characterized in that the masking substance in the composition after exposure to the composition of the indicator reagent forms a chelate luminescent complex. 5. The marking composition according to claim 4, characterized in that the masking substance in the composition is a compound of at least one rare earth metal. 6. The marking composition according to claim 1, characterized in that the masking substance in the composition is an inorganic phosphor. 7. The marking composition according to claim 1, characterized in that the masking substance in the composition is an organic phosphor. 8. The marking composition according to claim 1, characterized in that the particles of SiO ₂ , Al ₂ O ₃ , TiO ₂ , CaCO ₃ , ZnO ₂ , polymer microfibers and acrylate hydrogels are used as an inert carrier in the composition. 9. The marking composition according to claim 1, characterized in that the average particle size of the inert carrier in the composition is 1-1000 μm. 10. The method of marking and identification of a valuable document, which consists in entering into a valuable document protected from falsification, the marking composition and subsequent exposure to the marking composition of an indicator reagent, which results in the formation of a chelate complex in the zone of making the marking composition in a valuable document, characterized in that the chelate complex resulting from the action of the indicator reagent on the marking composition according to claim 1 does not luminesce at room temperature, and at when it is cooled to a negative temperature, luminescence reversibly appears, which disappears when heated to room temperature. 11. The method according to p. 10, characterized in that the marking composition included in the valuable document is not colored or slightly colored. 12. The method according to p. 10, characterized in that the marking composition included in the valuable document does not luminesce or has weak luminescence. 13. The method according to p. 10, characterized in that the marking composition contains at least one rare earth metal compound. 14. The method according to p. 10, characterized in that the marking composition is included in the valuable document at the stage of its manufacture. 15. The method according to p. 10, characterized in that the marking composition is included in the manufactured valuable document. 16. The method according to p. 10, characterized in that the resulting chelate complex is not colored or slightly colored. 17. The method according to p. 10, characterized in that the reversible appearance of luminescence during cooling of the chelate complex in a valuable document is recorded with the naked eye of the observer. 18. The method according to p. 10, characterized in that the luminescence spectrum that reversibly appears upon cooling of the chelate complex in a valuable document is recorded by a spectrofluorimeter. 19. The method according to p. 10, characterized in that the marking composition is introduced into the paper used for the manufacture of a valuable document, so that the marking composition is distributed throughout the volume of paper. 20. The method according to p. 19, characterized in that the marking composition is distributed in a given layer and / or a given section of paper. 21. The method according to p. 10, characterized in that the marking composition is applied to the printing ink and / or varnish used to produce a valuable document.