EP0071124B1 - Forge-proof document and method for its production - Google Patents

Abstract

The tamperproof document consists of a photographic material as information carrier which is laminated on one or both sides with a transparent foil. The foil is attached to the surface of the information carrier by a layer of adhesive containing poly-1,2-alkyleneimine. The document is eminently saft against falsification.

Description

The invention relates to a tamper-proof document that is laminated on both sides with plastic films, and to a method for producing the tamper-proof document.

Forgery-proof documents are becoming increasingly important. You will e.g. B. in the form of credit cards from banks, retail stores, oil companies, airlines or credit companies to facilitate cashless payments. Such documents contain information that relates to the owner as well as the body issuing the document and that is in both interests to be protected against counterfeiting. There has been no shortage of attempts to provide information carriers of the type mentioned above in a forgery-proof manner.

For example, it is known to laminate a card printed with information between two foils. In this case, the laminating film is prepared in places so that it does not adhere to the prepared areas on the paper surface of the films. An attempt to subsequently peel off the laminating film then has the consequence that when the unprepared areas are reached the tear breaks away from the paper surface due to the lower resistance and tears the paper surface (DE-OS 2511 367).

According to another proposal, a printed information carrier consisting of a paper card and a foil border, a so-called “composite ticking”, is welded between two transparent foils. In this way of working, the film border provides for an edge seal that encompasses the edges of the paper card, which makes it difficult to split the welded card (DE-OS 2 756 691).

From GB-PS 1 518946 it is known to weld a photographic paper as an information carrier into a pair of transparent laminated foils by applying pressure and temperature. Commercially available films are used for this purpose, which consist of an outer polyethylene terephthalate layer and an inner polyethylene layer.

A disadvantage of the known lamination processes is that the foils used for this purpose only bond imperfectly to the surface of the information carrier during welding and thus offer only limited protection against counterfeiting. Edge welding also does not mean a significant improvement under these circumstances, since it can be easily removed and replaced again. The known lamination processes also have the disadvantage that the laminated film can be separated from the paper backing by heating or by chemical means.

It is also known from US-A-4152 476 a credit or identification card in which the u. a. Information carrier formed from a photographic material adheres to a transparent film by means of a polyethyleneimine adhesive, while the back of the information carrier can be firmly connected to the corresponding cover layer. The information carrier is normally smaller in size than the finished card, so that the protruding parts of the cover foils are connected to one another and enclose the information carrier.

The card is not sufficiently forgery-proof.

EP-A-31 521 describes an information carrier which is connected to films on both sides by means of a radically crosslinkable mass and which, after being crosslinked, constitutes a tamper-proof document. The manufacturing method is complex and leads to products whose flatness still leaves something to be desired.

The invention has for its object to provide a forgery-proof document with an information carrier in the form of a photographically and printing-prepared photographic material, in which the entire surface of the information carrier is inextricably linked with a "- transparent film material and which on the Information attached to information carriers can no longer be accessed without destroying the information carrier and are therefore reliably protected against subsequent changes.

The invention relates to a forgery-proof document, consisting of an information carrier laminated with at least one transparent film made of a photographic material, which contains at least one layer made of a plastic and is characterized in that the photographic material has a layer containing gelatin on its front and back has, on both sides with the transparent film via an adhesive layer containing poly-1,2-alkylenimine, and that the softening point of the plastic of the photographic material is lower than the softening point of the plastic of the transparent film.

The polyalkyleneimine resins used in the adhesive layer according to the invention are in principle polymerization products of ethyleneimine and its C and N substitution products. The reactions leading to such polymerization products, which may contain oxygen, sulfur or phosphorus as heteroatoms in addition to nitrogen, are described in “Methods of Organic Chemistry (Houben-Weyl)” Volume XIV / 2, pages 568-579. Details of polymerized C-alkyl and N-alkyl derivatives of ethyleneimine can be found in German Patents 888170 and 914 325. Further attention is drawn to G.D. Jones, J. Org. Chem. 9, 484 (1944); L.D. Klapp, Am. Soc. 70, 184 (1948); Y. Minoura, M. Takebayashi and C.C. Price, Am. Soc. 81: 4689 (1959); H. Bestian, Ang. Ch. 62, 451 (1950).

As particularly suitable polyalkyleneimine resins homopolymers or copolymers of ethyleneimine, propyleneimine and butyleneimine have been found, e.g. B. those described in US Pat. No. 3,418,204 and in particular those described in US Pat. No. 3,909,469. Polyethyleneimine with a molecular weight of 40,000 to 60,000 is preferred.

The present adhesive layers are produced from non-gelling aqueous solutions or dispersions which contain polyalkyleneimine, optionally an acid or an alkylating agent and preferably a modifying agent. Suitable modifiers are saturated or unsaturated lower aliphatic ketones and aldehydes, preferably with up to 6 carbon atoms, e.g. B. formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, chloral, acetone or acrolein. A preferred modifier is formaldehyde.

Polyfunctional compounds which are able to react with the poly-1,2-alkyleneimine, in particular with its imino groups, have also proven to be suitable modifiers. Examples are polyhalohydrins, polyisocyanates, polyepoxides and polyaziridinyl compounds, such as. B. epichlorohydrin, hexamethylene diisocyanate, polyvinylcyclohexene dioxide, tris (1-aziridinyl) phosphine oxide, finally unsaturated carboxylic acids and their derivatives such as chlorides and esters, e.g. As acrylic acid, acrylic acid chloride or acrylates.

The production of the polyalkyleneimine as a prepolymer or its crosslinking or chain extension is accelerated by acids or alkylating agents. Suitable acids for this purpose are inorganic and organic acids, e.g. B. aliphatic carboxylic acids with up to 6 carbon atoms such. B. acetic acid, propionic acid, butyric acid, malonic acid and succinic acid or their anhydrides. Acetic acid is preferred. In principle, carboxylic acids can also be used which have only limited solubility in water. In these cases it is possible to increase the solubility of the carboxylic acids by placing them in an organic solvent that is miscible with water, e.g. B. alcohol dissolves. The same effect is shown by hydrohalic acids, sulfonic acids, or also boron fluoride, borofluoride etherate, diazonium fluoroborates, alkyl halides, dialkyl sulfates, carboxylic acid and sulfonic acid chlorides or sulfonic acid esters. But also compounds that split off acids, such as. B. β-chloroethylamine, amine hydrochloride and also certain silver salts, especially silver perchlorates, are effective.

The composition of the adhesive layer solution can be varied within wide limits. An example of a suitable composition is an adhesive layer solution which contains 0.05 to 10% by weight of poly-1,2-alkyleneimine, 0.01 to 2% by weight of modifying agent and optionally 0.01 to 1% by weight a carboxylic acid, based on the carboxyl groups of the carboxylic acid. A preferred adhesive layer composition contains 0.1 to 5% by weight of polyethyleneimine, 0.05 to 1% by weight of modifier, optionally 0.05 to 0.2% by weight of a carboxylic acid as defined above and the balance water or others additives necessary for setting certain properties. The adhesive layers used in the manner according to the invention develop excellent adhesive properties and a surprising resistance to water during drying.

In addition to the substances already mentioned, a small amount of a thickener can be added to the aqueous adhesive layer solution, or a resin which further improves the water resistance of the adhesive layer after heat treatment, or a defoaming agent in order to prevent foaming, which can have disadvantages for the use of the adhesive solution . If the use of a thickener, an additional resin or a defoamer is intended, these additives can be used individually or together in the following amounts by weight: 0.01 to 1 wt .-% thickener, e.g. B. a thickener from the group of hydroxyethyl cellulose, polyvinyl alcohol and methyl cellulose, 0.01 to 2 wt .-% of a resin, such as melamine formaldehyde or urea formaldehyde resin, and 0.01 to 0.1 wt .-% of a defoamer, such as. B. Dimethylpolysiloxane.

The weight ratio of the thickeners or the resins to the polyalkyleneimine depends on the nature of these additives. In general, ratios of 1: to 1: 100, preferably 1: 3 to 1: 30, are suitable.

Thermoplastics such as z. B. polyolefins such as polyethylene, polypropylene, cellulose esters, polyvinyl acetate, polystyrene, polyvinyl chloride, polyvinylidene chloride, polyvinyl fluoride, polytetrahalogenethylene, polycarbonate, in particular based on bisphenol A, polyester, in particular based on polyethylene and polybutylene terephthalate, polyamides, e.g. B. polyamide-6 or polyamide-6,6, polyamide-12 or copolyamides.

So-called composite films made of individual films of the same and different chemical composition can of course also be used. Examples include: polyethylene / polyamides, polypropylene / polyamides or polyolefin films with other film materials such as polyesters, e.g. B. polyethylene terephthalate. Suitable films and composite films are described in Ullmanns Encyklopadie der Technischen Chemie, 4th edition, volume 11, pages 673 ff.

If composite foils are used for lamination, the individual foils can be connected by customary known, but preferably by the same adhesive layers that also serve to connect the composite foil to the information carrier.

The thickness of the foils used according to the invention depends on the desired rigidity of the identification document. In general, film thicknesses between 15 and 250 microns will suffice; thicknesses between 50 and 200 µm are preferred.

The surface of the film intended to absorb the adhesive layer composition can be subjected to a pretreatment prior to coating to improve the bond between the film and the adhesive layer, which ensures a uniform application of the coating solution and increases its adhesive strength. Good results are obtained e.g. B. with a conventional corona treatment.

It is of course also possible to support the adhesion of the adhesive layer applied to the carrier film by other measures, such as. B. by applying a suitable substrate layer.

The application of the adhesive layer composition to the film can be carried out using the usual methods in the paint industry, such as. B. spraying, rolling, knife coating, printing, dipping, spinning, flooding, brushing, brushing, etc. take place.

The dry layer thickness of the adhesive layer depends on the desired requirements and the expected adhesive effect. In general, usable results will be achieved with dry film thicknesses of 0.05 to 10 f.lm. Dry layer thicknesses of 0.05 to 2 f.Lm. Dry layer applications of 0.05-0.5 g per m ² , based on poly-1,2-alkenyleneimine, are particularly preferred.

As a rule, the information carrier will consist of a photographic material containing a light-sensitive silver halide emulsion layer that is constructed in the usual way, that is to say a light-sensitive layer, and contains at least one layer made of a plastic. The silver or dye information contained in the photosensitive layer is produced by imagewise exposure and the usual photographic processing. Both photographic paper and films containing black and white or color photographic records, image and / or characters and / or other information or other identification features can be used as information carriers. The layer support of such photographic information supports can consist of the usual materials used in technical or image photography. Examples include polyolefin-laminated papers and the usual film documents, e.g. B. from cellulose triacetate or polyester, optionally called pigmented, opaque support. The photographic emulsion or auxiliary layers of such information carriers have the compositions generally used in photographic materials.

Examples of light-sensitive photographic layers with which the information carrier can be equipped are layers which are based on non-sensitized silver halide emulsions or spectrally sensitized silver halide emulsions. The known gelatin layers used for the various photographic black-and-white and color processes, negative, positive and diffusion transfer processes or printing processes are therefore suitable. Not only gelatin alone can be contained as a binder in the photographic gelatin layers. In addition to gelatin, you can also use chemically modified gelatins, e.g. B. acylated, acetylated, hydroxylated, esterified or modified by graft polymerization in a known manner gelatins, or mixtures with other hydrophilic colloids, eg. B. cellulose derivatives, polyvinyl alcohols, polyvinyl pyrrolidones, hydrolyzed polyvinyl acetates, alginic acid, colloidal ablumine or zein. The layers, whether photosensitive or not photosensitive, can also contain the usual additives for changing the mechanical properties of photographic layers, such as. B. polymers based on acrylate or methacrylate, polystyrene / maleic acid copolymers' or styrene / maleic anhydride-semi-alkyl ester copolymers, or coating aids such as polyethylene glycol aryl ether and other conventional photographic aids.

In addition to the information, the information carrier can contain further security or identification features of the most varied types,. which can be created both photographically and by lettering, printing or embossing. Of course, z. B. can also be attached by machine, magnetically and optically readable data. In this respect, the information carrier according to the invention does not differ in any way from the information carriers used in known documents.

Other security features, visible or imperceptible to the eye, e.g. B. from UV light absorbing substances can in the information carrier, for. B. in the layer support, if this consists of paper as a watermark, or in the outer film, for. B. in the composite film. Different possibilities of equipping forgery-proof documents with such security features are e.g. B. described in the following publications: DE-OS 3 013 238, DE-OS 1 446 851, DE-OS 2 908 742, US-PS 3 679 448, GB-PS 1 519 715, DE-AS 2 756 692, US -PS 2,373,540 and U.S. Patent 4,066,873.

If polyolefin-laminated paper is used as the layer support for the information carrier, it has proven expedient to equip the paper with a polyolefin, the melting point of which is about 10-30 ° C. lower than the melting point of the film of the film material carrying the adhesive layer.

To laminate the film provided with the adhesive layer on the gelatin-containing layer of the information carrier, the film is heated to about 50 to 150 ° C and pressed against the surface of the information carrier, so that a bubble and crease-free laminate is formed. The lamination is supported by applying pressures in the range of 1 to 10 kp / cm ³ .

The lamination, on both sides of the information carrier, which on the front and Back contains gelatin, is advantageously carried out continuously by bringing the individual information carriers together onto the foils running off the supply rolls and provided with the adhesive layer. The parts containing the information carriers can then be punched out of the resulting band-shaped laminate, the welded film being separated at a distance of approximately 1 to 2 mm from the edge of the information carrier, depending on the thickness of the information carrier. A wrapping of the information carrier which is closed on all sides is obtained, which makes subsequent edge welding unnecessary. Of course, discontinuous lamination using sheet-shaped pieces of film leads to the same results. The documents described are excellent forgery-proof. Just like the foils with the information carrier, the foil parts protruding beyond the information carrier are connected to one another in a practically inseparable manner. Even with the help of heat, the document can no longer be separated without completely destroying the information carrier.

Another important and surprising advantage of the identification documents or ID cards according to the invention with polyalkyleneimine adhesive layers lies in the excellent flatness. It is precisely in this respect that the documents according to the invention are superior to known ones.

example

100 g of an aqueous 2% by weight polyethyleneimine solution were mixed with 0.1 g glacial acetic acid and 2 ml of an aqueous 40% by weight formaldehyde solution and then applied to a polyethylene film. The surface of the polyethylene film was exposed to corona radiation before casting. The dried layer contained 0.1 g polyethyleneimine per m ² .

Conventional photographic paper was used as information carrier, the layer carrier of which consisted of paper laminated on both sides with polyethylene, which had an m ² weight of approximately 120 g. The softening point of the polyethylene of the support was 110 ° C. The support was equipped with a light-sensitive silver halide gelatin emulsion layer and with a gelatin-containing protective layer and back layer, both of the same composition. A picture of the ID card holder along with the corresponding information was exposed, developed and fixed on the information carrier.

The information carrier with the photographic and printing technology applied identification features was now placed between 2 of the above-mentioned polyethylene foils, the softening point of which was approximately 122 ° C., so that the adhesive layers of the foils came into contact with the two surfaces of the information carrier and the foils about 1 mm above the Protruding edge of the information carrier. The package was then passed between two rolls heated to 90 ° C. and pressed together with a pressure of approximately 1.5 kp / cm ² .

After the document had cooled, the polyethylene films were so firmly connected to the information carrier that when trying to separate the document after cutting the edge bonds while heated (about 100 ° C), the paper support of the information carrier was destroyed, but its remnants were removed from the films were recorded, which were also irreversibly stretched.

Comparative example

The example was repeated, using a two-component material based on a polyisocyanate and a resin component containing hydroxyl groups (laminating adhesive EPS 71 from Dr. Kurt.) Both for bonding the composite film itself and for bonding the composite film to the information carrier instead of the adhesive layer described in the example Herbert's Wuppertal) existing adhesive layer was used.

The flatness of the document was poor and the adhesion of the foils decreased over time, so that the glue could be removed after about a week without permanent damage to the information carrier.

Claims (12)

1. Forgery-proof document consisting of an information carrier which is laminated with at least one transparent film and consists of a photographic material containing at least one layer of a plastic material, characterised in that the photographic material has a gelatine-containing layer on its front and reverse side, is bonded to the transparent film on both sides by means of an adhesive layer containing a poly-1,2-al- kyleneimine, and in that the softening point of the plastic of the photographic material is lower than the softening point of the plastic of the transparent film.

2. Document according to Claim 1, characterised in that the adhesive layer contains 0.05 to 0.5 g of a poly-1,2-alkyleneimine per m².

3. Document according to Claims 1 and 2, characterised in that the poly-1,2-alkyleneimine is a polyalkyleneimine modified with ketones or aldehydes.

4. Document according to Claim 3, characterised in that the poly-1,2-alkyleneimine has been modified with formaldehyde.

5. Document according to Claims 1 to 4, characterised in that the poly-1,2-alkyleneimine is polyethyleneimine.

6. Document according to one of the preceding claims, characterised in that the adhesive layer contains a melamine-formaldehyde or urea-for- maidehyde resin in addition to a poly-1,2-al- kyleneimine.

7. Document according to one of the preceding claims, characterised in that the layer support of the photographic material is a paper coated on both sides with polyolefin.

8. Document according to one of the preceding claims, characterised in that he transparent film consists of one or more thermoplasts from the group comprising polyethylene, cellulose ester, polyvinyl acetate, polypropylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polyvinyl fluoride, polytetrahalogenoethylene, polycarbonate based on bisphenol A, polyethylene terephthalate, polybutylene . terephthalate and polyamide.

9. Document according to Claim 8, characterised in that a composite film formed from two or more of the films is used.

10. Document according to Claim 9, characterised in that the film of the composite material which carries the adhesive layer consists of polyethylene.

11. Process for the production of forgery-proof documents according to Claim 1 by laminating both sides of the information carrier consisting of a photographic material with films, characterised in that the film is coated with an aqueous solution containing a poly-1,2-alkyleneimine, the layer is dried and laminated, with simultaneous heating and under pressure, on to both sides of the information carrier which has been provided with identifying features by means of image-wise exposure and photographic processing and whose front and reverse sides contain gelatine.

12. Process according to Claim 11, characterised in that the aqueous solution contains 0.05 to 10 % by weight of poly-1,2-alkyleneimine, 0.01 to 2 % by weight of an aldehyde or ketone and, optionally, 0.01 to 1 % by weight of a carboxylic acid, based on the content of carboxyl groups.