EP0018887B1 - Process for the manufacture of a tamperproof identification card comprising photographs, and card obtained by this process - Google Patents

Abstract

A tamperproof identification card such as a passport or credit card is provided. A diazo photosensitive composition is intimately mixed with a thermo-adhesive resin and is carefully deposited as a uniformly thin layer in one or more zones on a plastic support material. The zones of the photosensitive compositions are developed to reproduce identifying information such as a photograph, identification number, etc. A plastic protective film is then laminated to the support to protect the identifying information. Since the adhesive resin material is intimately mixed throughout the photosensitive composition, the protective plastic film cannot be removed without destroying the information.

Description

The present invention relates to a method for manufacturing a tamper-proof identification card comprising photographs as well as a card obtained by this method.

The use of such cards has become very widespread in recent years, in particular in all operations requiring identity control, such as passport, credit cards, etc. Cards of this type, for example, are known. a polyvinyl chloride support on which is stuck a thin support coated with a photograph of the card holder next to which are mentioned the identity of the latter and certain information concerning him.

A transparent plastic film is superficially bonded so as to protect the assembly against damage. Such a card has the drawback of not being completely inviolable because the protective film can be relatively easily peeled off and the photograph retouched, so that fraud is relatively easy. To remedy this drawback, it has been proposed to carry out photography by depositing a photosensitive layer directly on the support in the manner described in French patent 2 129 198. In this patent, the polyvinyl chloride support or the like, is coated with a photosensitive layer composed of a product sold under the trade name DYLUX. The photosensitive material can be diffused in the mass of the support itself or in the binder layer deposited on the support.

In this process, the alphanumeric inscriptions and the photography are carried out when the card already has the finished appearance, that is to say coated with its transparent protective film.

The drawback of cards produced according to this method is mainly due to the fact that the above-mentioned photosensitive emulsion is not temperature stable. During the complexing operation, which generally takes place hot, the photosensitive layer is liable to degrade.

On the other hand, the stabilization of the background of the photography is imperfect using a simple exposure to light. Because the photosensitive layer is protected by a transparent film, it is then no longer possible to stabilize the image after development by washing.

In US Patent No. 3,002,851, it has been proposed to coat a polyvinyl chloride support with a photosensitive diazo solution such as paradiazodiphenylamine condensed formaldehyde, then to exert pressure on said layer at high temperature in order to migrate partially this layer in the support. However, it is found that such a layer has poor adhesion to the support. If the assembly is complexed with a protective film usually used for identification cards, there is not only a low adhesion of the latter, but also a transfer of the images on the protective film during rolling. Furthermore, such a layer can be easily attacked by solvents such as acetone. In other words, such an identification card does not at all have the character of inviolability currently sought for such cards.

More recently, it has been proposed in US Patent No. 4,115,618 a protective film coated with a layer of polyvinyl alcohol and vinyl acetate allowing good adhesion of said protective film on photographic film type previously glued to the support. The drawbacks of such a system are linked to the production of silver-type photographs. Such photographs are expensive and their implementation in this process is very delicate, because it is necessary to apply the protective film immediately after development thereof (still wet photo). In addition, such a card is not really inviolable since it is possible to completely remove the protective film and the photographs, and replace them with new photographs and a new protective film. In addition, one. such a system leads to a map having local excess thicknesses since the photographs thus produced have a thickness of a few tenths of a millimeter. FR-A-2,059,125, FR-A-2,059,126 and US-A-4,108,664 teach that a composition comprising a diazonium salt must, in order to adhere to a support of plastic material such as PVC, a coupler and stabilizing aids such as polyvinyl acetate.

• a) à prendre un support en matière plastique transparent ou opaque sur lequel on dépose localement par sérigraphie, une solution photosensible de viscosité comprise entre 600 cps et 4.000 cps à 20°C comportant au moins un sel de diazonium, un copulant, des adjuvants de stabilisation, une première résine ayant un point de ramollissement VICAT compris entre 40°C et 140°C et de préférence compris entre 50°C et 100°C et un solvant ayant une vitesse d'évaporation relative supérieure à 25, en prenant pour référence une vitesse égale à 1 pour l'ether éthylique,
• b) à laisser sécher la couche ainsi déposée,
• c) à insoler à froid la couche photosensible à l'aide d'un rayonnement ultraviolet à travers un original positif à reproduire, de façon à détruire le sel de diazonium dans les zones exposées,
• d) à développer les zones non insolées de la couche photosensible par passage dans un fluide calcalin,
• e) à disposer, après séchage, un film de matière plastique transparent ou opaque, ayant au moins une couche superficielle d'une seconde résine ayant un point de ramollissement VICAT compris entre 40°C et 140°C et de préférence compris entre 50°C et 100°C, la face thermocollante du film transparent étant en contact avec le support et/ou les images, le film et le support n'étant pas choisis simultanément en matériau opaque,
• f) à assembler le film et le support par chauffage à une température supérieure au plus élevé des points VICAT de la première ou de la seconde résine, sous pression,
• g) à refroidir l'ensemble à température ambiante, le film et le support ne pouvant alors être séparés sans détériorer les images.

In all the systems known in the prior art, no identification card exhibits total adhesion as well between the support and the photograph as between the photograph and the protective film, without any excess thickness, while being simple to produce and cheap. The method according to the invention overcomes these drawbacks. The method for producing a tamper-proof identification card according to the invention consists of:

• a) to take a transparent or opaque plastic support on which is deposited locally by screen printing, a photosensitive solution of viscosity between 600 cps and 4,000 cps at 20 ° C comprising at least a diazonium salt, a coupler, adjuvants stabilization, a first resin having a VICAT softening point between 40 ° C and 140 ° C and preferably between 50 ° C and 100 ° C and a solvent having a relative evaporation rate greater than 25, taking as reference a speed equal to 1 for ethyl ether,
• b) allowing the layer thus deposited to dry,
• c) cold exposure of the photosensitive layer using ultraviolet radiation through a positive original to be reproduced, so as to destroy the diazonium salt in the exposed areas,
• d) developing the non-exposed areas of the photosensitive layer by passing through a calcaline fluid,
• e) having, after drying, a transparent or opaque plastic film, having at least one surface layer of a second resin having a VICAT softening point between 40 ° C and 140 ° C and preferably between 50 ° C and 100 ° C., the fusible face of the transparent film being in contact with the support and / or the images, the film and the support not being chosen simultaneously from opaque material,
• f) assembling the film and the support by heating to a temperature higher than the highest of the VICAT points of the first or second resin, under pressure,
• g) cooling the assembly to ambient temperature, the film and the support then being unable to be separated without damaging the images.

According to a preferred embodiment, the invention is characterized in that the solvent is a solvent for the support. Such a process, by the use of heat-bonding resins in the photosensitive layer, in fact allows excellent adhesion of the photographs to the support, while the presence of a second heat-bonding resin on the protective film allows excellent adhesion of said photographs to said film. Thus, photographs cannot be removed from the film or the support.

In addition, it is not necessary in the method according to the invention to immediately paste onto the developed photograph, the protective film to make the identification card inviolable. This laminating operation can be carried out several hours or days after the development of the images, without any time limitation. It has been found that in order to achieve total inviolability of the identification cards carrying a sensitive diazo layer, it was surprisingly necessary to produce a photosensitive layer comprising an intimate mixture of the photosensitive products and of the heat-bonding resin. This intimate mixing must be carried out before coating the photosensitive layer on the support (or the protective film) to achieve the desired result.

In fact, it can be seen that when a photosensitive layer and then a heat-bonding layer are successively deposited (which may be either an overlay of the first resin or the second resin present on the protective film), it is not possible to obtain a tamper-proof identification card, the protective film being able to be easily peeled off in the zones corresponding to the photosensitive layer. According to the invention, after entering information on the card (code, photo, etc.), heat sealing is carried out at high temperature, the heat sealing often being carried out under pressure. There was therefore an unfavorable prejudice for obtaining fine and clear inscriptions and perfectly defined photos. According to the present invention, this unfavorable prejudice has been overcome by the simultaneous choice of diazo compositions of defined viscosity and of a method of deposition of the compositions by screen printing.

To further increase the adhesion of the photosensitive layer to the support, it is preferable to use a solvent which is a solvent for the support so as to slightly penetrate said layer into said support.

In order to obtain total inviolability, the first and second resins will have a VICAT softening point of between 40 ° C and 140 ° C and preferably between 50 ° C and 100 ° C. These resins will preferably be chosen from polyvinyl acetate, polyvinyl aceto-chloride, polyvinyl chloride and polyesters. The choice of the first resin which is intimately mixed in a solvent with the photosensitive compounds (diazonium salt, coupler, adjuvants) will obviously be made according to its compatibility with these various elements of the photosensitive layer.

By compatibility is meant the non-precipitation of the resin solution when the elements of the photosensitive composition are introduced, or vice versa. By simple manipulations, those skilled in the art will note the existence or not of a precipitation of the photosensitive solution.

As diazonium salts which can be used in the photosensitive compositions of the invention, any diazonium salt soluble in organic solvents can be chosen.

• - les para dialkylamino benzène diazonium substitués ou non par des groupements alkyle, alkoxy, halogène, etc...
• - les paramorpholino benzène diazonium, substitués ou non par des groupements alkyle, alcoxy, halogène, etc...
• - les para alkyl mercapto benzène diazonium, éventuellement substitués, de préférence par des groupements alkoxy.

Preferably, the diazonium salt will be chosen from:

• - para dialkylamino benzene diazonium substituted or not by alkyl, alkoxy, halogen groups, etc ...
• - paramorpholino benzene diazonium, substituted or not by alkyl, alkoxy, halogen groups, etc ...
• - para alkyl mercapto benzene diazonium, optionally substituted, preferably by alkoxy groups.

• - les mono-, di ou tri phénols benzéniques, le noyau benzénique étant substitué ou non, tels que les dérivés des acides α, þ et y résorcyliques,
• - les dérivés du naphtalène, plus particulièrement ceux du mono ou dihydroxy naphtalène ou les dérivés de l'acide f3 hydroxy naphtoïque,
• - les produits à méthylène actif, tels que les dérivés de l'acéto acétanilide.

The couplers which can be used in the layer of the present invention will be soluble in organic solvents. Preferably, we will use:

• - benzene mono-, di or tri phenols, the benzene ring being substituted or not, such as derivatives of α, þ and resorcylic acids,
• naphthalene derivatives, more particularly those of mono or dihydroxy naphthalene or derivatives of f3 hydroxy naphthoic acid,
• - products with active methylene, such as derivatives of acetoacetanilide.

We will incorporate into the photosensitive solution, with the diazonium salt and the coupling agent stabilizers necessary to avoid, in a manner known per se, the precopulation of the diazonium salt and of the coupler.

The proportions between the diazonium salt and the coupler will vary, by weight, between 0.1 and 10 and preferably between 0.3 and 3.

After evaporation of the solvents, the quantity of diazonium salt and of coupler present on the support in the photosensitive zones will vary between 5% and 50% by weight, while the quantity of first resin (alone or mixture of resins) will vary between 50% and 95% by weight (from these proportions, all adjuvants are excluded).

The proportions of these various components will vary according to the thickness of the deposited layer and / or the image density that it is desired to obtain.

Given the supports usually used for the production of an identification card, it is necessary to use photosensitive solutions in a solvent medium to obtain good adhesion of these to the support.

In addition, the choice of the solvent among the solvents of the support makes it possible to obtain an exceptional adhesion of the layer as well as the reproduction of the half-tones.

Furthermore, it was found that it was necessary to use the coating technique by screen printing to obtain a coating of good quality, precise in its contours while being inexpensive and suitable for the production of small series.

For this purpose, the Applicant has found that the photosensitive solution must have a viscosity of between 600 cps and 4.000 cps at 20 ° C. When the viscosity of the photosensitive layer is less than 600 cps, the solution is too fluid and flows alone through the mesh of the screen, without using the squeegee used for this purpose: the resulting work is then too imprecise for making identification cards.

When the viscosity of the solution is greater than 4,000 cps, the solution is then too viscous to pass through the finest meshes of the "silk screen".

To obtain photosensitive solutions having such viscosities, it has been found that it is necessary to use solvents having relative evaporation rates greater than 25 and preferably 30, taking as a reference a speed equal to 1 for l 'ethyl ether.

By way of nonlimiting example, the relative rates of evaporation of common solvents which are suitable in the context of the present invention will be found in the table below:

To obtain a viscosity between 600 and 4,000 cps at 20 ° C with solvents having an evaporation rate> to 25, it is necessary to use solutions containing from 15% to 40% by weight of dry extract and 60% to 85% solvent.

To deposit the photosensitive solutions defined above, on a support by screen printing, we will preferably use wefts of nylon or polyester threads comprising from 70 to 165 threads / cm.

The higher the desired image resolution, the finer the screens used.

The supports used in the context of the present invention will preferably be made of polyvinyl chloride or vinyl acetochloride, optionally comprising fillers and / or dyes.

After the layers deposited on this support have dried, it is then possible to produce the desired images in the photosensitive zones of the card. For this purpose, we will use the classic cold insolation technique using ultraviolet radiation through a positive to reproduce.

We could use for example, an exhibition frame intended for offset plates such as those sold under the name NU-ARC. It is indeed important not to melt the resin during of this operation and, for this purpose, the plan drawing machines, for example; cannot be used because the insolation part of these machines is at too high a temperature.

The images are then developed in ammonia vapors. The card is then ready to be laminated with a protective film under pressure and in the presence of heat, in a manner known per se.

As protective film, use will preferably be made of a polyvinyl chloride, vinyl acetochloride, polyester or polystyrene film.

When the protective film is made of a material identical to that which can constitute the first or the second resin, it is possible in this case to avoid coating this second resin on the said film since the latter is then directly fusible.

Furthermore, all the steps of the method according to the invention make it possible to deposit magnetic tracks, for example on the back of the card support without any deterioration of these during the manufacture of said card.

Likewise, embossings representing numbers, letters, etc. can be produced on said card, in a manner known per se.

• - fig. 1, une plaque comportant plusieurs cartes d'identification,
• - fig. 2, une vue en coupe d'une carte avant plastification,
• - fig. 3, une vue en coupe de la même carte après plastification,
• - fig. 4, une variante dans laquelle le film de protection est sensibilisé avant plastification.

The invention will be better understood with the aid of the following embodiments given without limitation, together with the figures which represent:

• - fig. 1, a plate comprising several identification cards,
• - fig. 2, a sectional view of a card before laminating,
• - fig. 3, a sectional view of the same card after laminating,
• - fig. 4, a variant in which the protective film is sensitized before plasticization.

In fig. 1, there is shown a plate 1 bearing 36 identification cards produced simultaneously according to the method of the invention.

All these cards are identical to card 2, at the top left of the figure. On this card, three photosensitive "stamps" 13, 14 and 15 have been indicated on which will be represented respectively the photograph of the holder, an identification number and his signature.

These stamps are deposited by screen printing, as described above. For more details on the implementation of this technique, one can refer to the work entitled "The Techniques of the Serigraphy" - Michel CAZA - Presses of the Present Time.

Fig. 2 is a sectional view of an identification card as shown in FIG 1. This section is made before plasticizing the card. The support 20 is coated with photosensitive zones 21 and 22 deposited by screen printing. A photographic positive is then deposited on each sensitive part of the card and cold exposure of the entire support is carried out with ultraviolet radiation using a "NU-ARC" type chassis.

The colored parts are then developed by passing through an ammonia atmosphere.

The card is then coated on both sides with a transparent protective film, as shown in fig. 3 by references 23 and 24. Then hot pressing is carried out under the usual conditions well known to those skilled in the art in this type of application.

In fig. 4, an alternative embodiment of the invention has been shown in which the photosensitive stamps 31 and 32 have been deposited on the protective film 33.

The core 30 of the card coated with the protective film 34 is then associated with the protective film 33 as in FIG. 3, by hot pressing.

Example 1

We realize the following solution:

The viscosity of the solution obtained is 1,250 cps.

This solution is coated on a polyvinyl chloride support having magnetic tracks on the back using a "silk screen" in monofilament polyester yarn of weft 100 from Etablissements BUISINE having a mesh opening of 58 microns, a wire diameter of 40 microns and a thickness of 65 microns.

The thickness of the deposited layer, after evaporation of the solvent is 5 microns. We realize then the sunstroke for 30 seconds on a NU-ARC type frame through a raster photographic positive original (frame 150, that is to say 150 points per 2.54 cm). The image is then developed by passing through ammonia vapors and a positive blue-black image is obtained which adheres perfectly to the support. Said card (or set of cards, as described in FIG. 1) is then coated with a sheet of transparent vinyl acetochloride and complexing is carried out at 110 ° C. under pressure.

After cooling, a map is obtained in which all the points of the grid are perfectly reproduced and sharp. In addition, it is not possible to separate the protective film and the support in the areas where the image is located, even using a razor blade, without destroying it completely. In addition, we also note that even if the entire card is heated to 140 ° C. the film cannot be removed from the support in the image areas. In addition, at such a temperature, the card is no longer reusable.

Example 2

We realize the following solution:

The solution obtained has a viscosity of 600 cps.

This solution is coated on a polyvinyl chloride support as in Example 1. After exposure and development, a brown-sepia image is obtained. Complexing is then carried out at 110 ° C. under pressure with a transparent polyvinyl chloride protective film coated with a layer 3 microns thick of polyvinyl acetate. The same inviolability results are obtained for the card as in Example 1.

Example 3

We realize the following solution:

A photosensitive solution with a viscosity of 2,500 cps is obtained. This solution is deposited on a vinyl acetochloride support using a 70 frame (opening: 90 microns - film size: 55 microns - frame thickness: 90 microns).

The thickness of the deposited layer is 6 microns. We then proceed to the insolation and the development of the images as in Example 1. We obtain a positive brown-black image.

Complexation (or “plasticization” of the card) is then carried out at 110 ° C. under pressure with a film of polyethylene terephthalate coated with a layer of 2 microns of polyester resin DYNAPOL L 206 (linear polyester obtained by polycondensation of aromatic dicarboxylic acid and aliphatic diol and manufactured by the company DYNAMIT NOBEL). The same inviolability results are obtained as in Example 1.

Example 4

We realize the following solution:

The viscosity of the solution obtained is 600 cps.

A card is produced with this solution as described in Example 1 under the same conditions (blue-black color image).

The same inviolability results are obtained as in Example 1.

Example 5

We realize the following solution:

This solution has a viscosity of 1,600 cps.

A layer 3 microns thick is coated with said solution using a 140 weft (mesh opening: 33 microns - wire diameter: 37 microns - weft thickness: 66 microns) on a transparent film of protection of vinyl acetochloride. After exposure and development as in Example 1, a brown-black image is obtained. The film (with the developed images) is then complexed at 110 ° C and under pressure with a polyvinyl chloride support. The same results are obtained as in Example 1.

Claims (19)

1. A process for producing a tamper-proof identification card comprising symbols or images enabling its bearer to be recognised, the process consisting:

a) in taking a support of a transparent or opaque plastic material on which is locally deposited by screen printing a photosensitive solution with a viscosity between 600 cps and 4,000 cps at 20°C comprising at least one diazonium salt, a coupler, stabilising additives, a first resin having a VICAT softening point between 40°C and 140°C and preferably between 50°C and 100°C, and a solvent having a relative time for evaporation greater than 25, taking as reference a time equal to 1 for ethyl ether, b) in allowing the layer thus deposited to dry,

c) in exposing the photosensitive layer to light in the cold with the aid of an ultraviolet radiation through an original to be reproduced, so as to destroy the diazonium salt in the exposed zones,

d) in developing, by passing in an alkaline fluid, the zones of the photosensitive layer which have not been exposed to light,

e) in arranging, after drying, a film of transparent or opaque plastic material comprising at least one surface layer of a second resin having a VICAT softening point between 40°C and 140°C, and preferably between 50°C and 100°C, the thermo-adhesive surface of the transparent or opaque film being in contact with the support and/or the images, the film and the support chosen not being simultaneously of an opaque material,

f) in assembling the film and the support by heating to a temperature greater than the higher of the VICAT points of the first or the second resin, and under pressure,

g) in cooling the assembly to ambient temperature, the film and the support being then incapable of being separated without degrading the images.

2. A process according to Claim 1, characterised in that the solvent is a solvent for the support.

3. A process according to either of Claims 1 or 2, characterised in that the first and second resins are chosen from polyvinyl acetate, polyvinyl acetate/chlorides, polyvinyl chloride and polyester resins.

4. A process according to one of Claims 1 to 3, characterised in that the dry extract of the photosensitive solution contains from 5 to 50% by weight of diazonium salt and coupler and from 50% to 95% by weight of thermo-adhesive resin, these proportions excluding any adjuvants.

5. A process according to one of Claims 1 to 4, characterised in that the photosensitive solution contains from 15% to 40% by weight of dry extract and from 60% to 85% by weight of solvent.

6. A process according to one of Claims 1 to 5, characterised in that the relative time for evaporation of the solvent of the photosensitive solution is greater than 30.

7. A process according to one of Claims 1 to 6, characterised in that the thickness of the deposited photosensitive layer, after evaporation of the solvents, is between 1 and 10 microns.

8. A process according to one of Claims 1 to 7, characterised in that the support is chosen from polyvinyl chloride and vinyl acetate/chloride.

9. A process according to one of Claims 1 to 8, characterised in that the protective film is chosen from polyvinyl chloride, vinyl acetate/chloride, polyester and polystyrene.

10. An identification card comprising a support coated locally with a layer resulting from the exposure to light followed by development of a photosensitive layer based on diazonium salts, characterised in that the photosensitive layer comprises from 50% to 95% by weight of at least one first thermo-adhesive resin having a VICAT softening point between 40°C and 140°C and from 5% to 50% by weight of diazonium salt and coupler, these proportions excluding any adjuvants.

11. An identification card according to Claim 10, characterised in that the photosensitive layer before exposure to light and development additionally contains stabilisers and adjuvants.

12. An identification card according to Claim 10 or 11, characterised in that the photosensitive layer before exposure to light and development has a thickness between 1 and 10 microns.

13. An identification card according to one of Claims 10 to 12, characterised in that the weight ratio of the diazonium salt to the coupler is between 0.1 and 10 and preferably between 0.3 and 3.

14. An identification card according to one of Claims 10 to 13, characterised in that the first thermoadhesive resin is chosen from polyvinyl acetate, polyvinyl acetate/chlorides, polyvinyl chloride and polyester resins.

15. An identification card according to one of Claims 10 to 14, characterised in that the support is chosen from polyvinyl chloride and vinyl acetate/chloride.

16. An identification card according to one of Claims 10 to 15, characterised in that it is coated with a transparent protective film of polyvinyl chloride, vinyl acetate/chloride or vinyl acetate, if necessary coated with a second thermo-adhesive resin with a VICAT point between 40°C and 140°C and preferably between 50°C and 100°C.

17. An identification card according to one of Claims 10 to 15, characterised in that it is coated with a transparent protective film of polyester coated with a second thermo-adhesive resin with a VICAT point between 40°C and 140°C and preferably between 50°C and 100°C.

18. An identification card according to one of Claims 16 or 17, characterised in that the second resin is chosen from polyvinyl acetate, polyvinyl acetate/chlorides, polyvinyl chloride and polyester resins.

19. An identification card according to one of Claims 10 to 18, characterised in that it additionally comprises embossings and/or one or more magnetic tracks.

Images