EP1109675B2 - Method and product for protecting an object with a soluble binder security print - Google Patents

Abstract

A security imprint (4) is interposed between a protective film (2) of synthetic material and a surface (8) of an object (9) to be protected, onto which surface the film is glued by means of an adhesive (3). The security imprint (4) includes an ink composition having at least one pigment, a bonding agent, and a soluble agent. The soluble agent dissolves in a solvent that is intended to release the adhesive (3) and produces a visible stain.

Description

The invention relates to the protection of an object against falsification and / or for authentication purposes and / or to guarantee its integrity, with the aid of a thin protective film - in particular transparent - in synthetic material intended to be stuck on one side of an object.

The object may be for example an official document (passport, identity card, driver's license ...) bearing variable information (surname, first name, address, ... of the holder) to protect against attempts to falsify . In this case, the film is transparent. It can also be an official document, a packaging or a product or any article on which the presence of the film guarantees the authenticity of the object and / or its integrity (ie say the fact that it has not been previously used, or consumed, or violated). The film is not necessarily transparent, but incorporates security reasons impossible or difficult to reproduce (hologram, anti-photocopy printing, invisible pigments in visible light but visible in non-visible light ...).

Attempts to falsify, counterfeit, or tamper with film-protected objects usually consist of peeling off the film from the object using a solvent used to dissolve the adhesive that keeps the film stuck on. the object, without damaging the object, or the inscriptions it carries, nor, preferably, the protective film.

Throughout the text, the term "adhesive" generally refers to any composition having the property of adhering under certain conditions, and thus encompasses not only self-adhesives (or pressure-sensitive adhesives), but also heat-activatable adhesives or heat sealable (or hot glue), and glues in general (mono or multicomponent).

The solvents used by the fraudsters can be aqueous polar solvents (water, aqueous detergent solution, or alcoholic ...), or non-aqueous polar solvents (acetone, alcohol, ...), or apolar solvents (hydrocarbons such as essence, ether, white spirit ...).

We already know ( FR 2.675.742 ) a protective film comprising patterns printed with an ink composition incorporating at least one hydrocarbon-soluble pigment.

Nevertheless, such pigments are rare and do not make it possible to obtain all the desired security reasons. In particular they offer a low variety of colors and effects. As a result, their presence can be detected by the experienced fraudsters.

Also known are reagent compositions that can be incorporated into papers, which are normally colorless, but react upon contact with a solvent to color.

In general, the polar solvent reagents are stained black and the apolar solvent reactants are stained blue. These reagents therefore make it possible to reveal an attempt to attack the paper with a solvent. They nevertheless have several disadvantages. In the first place, their reactivity decreases over time until it disappears, so that they can not provide long-term protection. Second, the coloring reaction in contact with the solvents implements poorly controlled chemical processes, and the reactivity of the reagents is not constant according to the manufacture, so that one is never sure that the amount of reagents incorporated into the paper during its manufacture effectively triggers the reaction. In other words, these colored reagents can not be used with great reliability. Thirdly, these reagents generally react with the adhesive compositions, which themselves contain solvents, plasticizers and wetting agents, so that they are not compatible with a film-on-bonding protection. the paper since a reaction is triggered during the application and taking of the adhesive, and even after setting.

Ink compositions incorporating reactive pigments which change color in contact with a solvent are also known. However, again, these reactive pigments react to the adhesive compositions. In addition, these pigments are also limited in number and nuance so that they offer a low variety of colors and effects, and can be detected by an informed observer.

The invention therefore aims to overcome these drawbacks by proposing a method and a product for protecting an object with the aid of a film adhered to one face of the object by means of which the attempts to detach the film by etching with solvents can be reliably, irreversibly revealed over a long period of time (without substantially reducing the efficiency of the detection over time), and this in a manner compatible with the bonding of the film on the object.

The invention also aims to prevent this protection function (by revealing attempts to detach the film) can not be detected in advance in the protected object, including simple visual observation by sophisticated fraudsters.

The invention also aims at enabling the realization of security prints with the aid of an ink composition incorporating this protection function by revealing attempts to attack polar solvents and / or apolar solvents, and which allows obtain all the desired patterns, colors and effects, as in the case of a traditional ink.

The invention also aims at providing a method of manufacturing a protection product according to the invention and an object protected by a protection method according to the invention.

The invention also aims to achieve these goals simply and economically, particularly by silk screen printing.

To do this, the invention relates to a method of protecting an object according to claim 1.

The invention also extends to the product obtained by the manufacturing method according to the invention. It therefore also relates to a product according to claim 16.

The invention also extends to the protected object by a protection method according to the invention. It therefore also relates to an object according to claim 25.

• au moins un agent soluble est choisi parmi les acrylates d'alkyles, les méthacrylates d'alkyles, leurs polymères et leurs copolymères,
• le liant incorpore un polyméthacrylate d'isobutyle à titre d'agent soluble,
• on utilise une composition d'encre dans laquelle au moins un agent soluble est formé d'un composé chimique ayant une faible masse moléculaire -notamment inférieure à 5000- de façon à pouvoir être soluble dans les solvants polaires et/ou apolaires ;
• pour réaliser une impression de sécurité, on utilise un liant comprenant une solution liquide comprenant un solvant volatile séchant à l'air, et au moins un agent soluble ;
• pour réaliser une impression de sécurité, on utilise une base d'encre sérigraphique comprenant au moins un agent soluble en solution dans un solvant contenant au moins 10% en volume -notamment majoritairement- du carbonate de propylène ;
• pour réaliser une impression de sécurité, on utilise un liant comprenant un blanc de coupage fugitif à l'eau ;
• on réalise une impression de sécurité sur une face de film que l'on colle ensuite sur l'objet ;
• on colle le film grâce à une couche d'adhésif préalablement imprimée sur le film ;
• on réalise, sur une même face du film, une impression de sécurité et une impression d'une couche d'adhésif ;
• on réalise l'impression d'une couche d'adhésif et une impression de sécurité de façon à ce quelles ne se chevauchent pas mutuellement ;
• on imprime sur le film une couche d'adhésif par sérigraphie en recouvrant une impression de sécurité préalablement réalisée sur le film ;
• on imprime une impression de sécurité sur une couche d'adhésif sans adhésion instantanée initiale préalablement réalisée sur le film ;
• une impression de sécurité est discontinue et présente la forme d'une trame ou de motifs ;
• une impression de sécurité est continue et s'étend en regard de toute la surface du film ;
• le film est choisi parmi un film monocouche, un film multicouche comprenant une superposition de couches imprimées par sérigraphie, de vernis et/ou d'encres, et un complexe multicouche de matières synthétiques superposées ;
• le film est formé d'au moins une matière synthétique choisie parmi un polyuréthane, un polyester, un polystyrène, un polypropylène et un polyéthylène ;
• le film présente une épaisseur globale comprise entre 5 et 500 microns ;
• on réalise une impression de sécurité par sérigraphie ;
• on utilise au moins un pigment choisi parmi les pigments visibles en lumière visible, et les pigments invisibles sous éclairage en lumière visible et photoluminescents sous éclairage par au moins une source de lumière non visible ; le pigment peut être ou non lui-même soluble comme le(les) agent(s) soluble(s) du liant, dans lesdits solvants aptes à décoller l'adhésif ;
• une impression de sécurité est interposée entre le film et une couche d'adhésif associée à ladite face de l'objet ;
• une impression de sécurité est interposée entre une couche d'adhésif associée au film et ladite face de l'objet ;
• une impression de sécurité est intégrée dans une couche d'adhésif sans chevauchement mutuel de l'impression de sécurité et de la couche d'adhésif.

Moreover, advantageously and according to the invention, a protection method, a manufacturing method, a product, and an object according to the invention are characterized by all or some of the following characteristics:

• at least one soluble agent is chosen from alkyl acrylates, alkyl methacrylates, their polymers and copolymers,
• the binder incorporates isobutyl polymethacrylate as a soluble agent,
• an ink composition is used in which at least one soluble agent is formed of a chemical compound having a low molecular weight - in particular less than 5000 - so as to be soluble in polar and / or apolar solvents;
• to make a security impression, a binder is used comprising a liquid solution comprising a volatile solvent drying in air, and at least one soluble agent;
• to make a security impression, use is made of a screen printing ink base comprising at least one soluble agent in solution in a solvent containing at least 10% by volume - especially predominantly - propylene carbonate;
• to make a security impression, using a binder comprising a fugitive water cut white;
• a security impression is made on a film face which is then glued to the object;
• the film is adhered by means of a layer of adhesive previously printed on the film;
• a security impression and an impression of an adhesive layer are made on one and the same side of the film;
• printing of an adhesive layer and security printing so that they do not overlap each other;
• a layer of adhesive is printed on the film by screen printing, covering a security print previously made on the film;
• printing a security impression on an adhesive layer without initial instantaneous adhesion previously made on the film;
• a security print is discontinuous and has the form of a frame or patterns;
• a security impression is continuous and extends across the entire surface of the film;
• the film is chosen from a monolayer film, a multilayer film comprising a superposition of layers printed by screen printing, varnish and / or inks, and a multilayer complex of superimposed synthetic materials;
• the film is formed of at least one synthetic material selected from polyurethane, polyester, polystyrene, polypropylene and polyethylene;
• the film has an overall thickness of between 5 and 500 microns;
• a security impression is made by screen printing;
• at least one pigment chosen from pigments visible in visible light, and invisible pigments under visible light and photoluminescent under illumination by at least one non-visible light source; the pigment may or may not itself be soluble as the agent (s) soluble (s) of the binder, in said solvents able to peel off the adhesive;
• a security impression is interposed between the film and an adhesive layer associated with said face of the object;
• a security impression is interposed between an adhesive layer associated with the film and said face of the object;
• a security print is embedded in an adhesive layer without mutual overlap of the security print and the adhesive layer.

The invention also relates to a protection method, a manufacturing method, a product and an object characterized in combination by all or some of the characteristics mentioned above or below.

• la figure 1 est une coupe transversale schématique d'un produit de protection selon un premier mode de réalisation de l'invention,
• la figure 2 est une coupe transversale schématique d'une première étape d'un procédé de protection d'un objet avec le produit de protection de la figure 1,
• la figure 3 est une coupe transversale schématique de l'objet protégé par le produit de protection de la figure 1 selon l'invention,
• les figures 4 et 5 sont des coupes transversales schématiques représentant, respectivement, un deuxième mode de réalisation et un troisième mode de réalisation d'un produit de protection selon l'invention,
• la figure 6 est une coupe transversale schématique représentant une variante de réalisation d'un procédé de protection selon l'invention,
• la figure 7 est une coupe transversale schématique représentant l'objet protégé obtenu selon la variante de la figure 6,
• les figures 8 et 9 sont des figures semblables aux figures 6 et 7 représentant une autre variante de réalisation d'un procédé de protection selon l'invention,
• les figures 10 et 11 sont des coupes transversales schématiques représentant, respectivement, un quatrième mode de réalisation et un cinquième mode de réalisation d'un produit de protection selon l'invention,
• la figure 12 est une coupe transversale schématique d'une autre variante de réalisation d'un procédé de protection selon l'invention dans laquelle on utilise un support d'impression intermédiaire,
• la figure 13 est une coupe transversale schématique représentant un objet protégé par le procédé de la figure 12,
• les figures 14 et 15 sont des vues semblables aux figures 12 et 13 représentant une autre variante de réalisation de l'invention.

Other objects, features and advantages of the invention appear from the following description which refers to the appended figures in which:

• the figure 1 is a schematic cross-section of a protection product according to a first embodiment of the invention,
• the figure 2 is a schematic cross section of a first step of a method of protecting an object with the protection product of the figure 1 ,
• the figure 3 is a schematic cross section of the object protected by the protection product of the figure 1 according to the invention,
• the Figures 4 and 5 are schematic cross-sections representing, respectively, a second embodiment and a third embodiment of a protection product according to the invention,
• the figure 6 is a schematic cross section showing an alternative embodiment of a protection method according to the invention,
• the figure 7 is a schematic cross section showing the protected object obtained according to the variant of the figure 6 ,
• the Figures 8 and 9 are figures similar to Figures 6 and 7 representing another variant embodiment of a protection method according to the invention,
• the Figures 10 and 11 are schematic cross-sections representing, respectively, a fourth embodiment and a fifth embodiment of a protection product according to the invention,
• the figure 12 is a schematic cross section of another variant embodiment of a protection method according to the invention in which an intermediate printing medium is used,
• the figure 13 is a schematic cross-section representing an object protected by the process of the figure 12 ,
• the Figures 14 and 15 are views similar to Figures 12 and 13 representing another variant embodiment of the invention.

In the figures, the thicknesses are exaggeratedly enlarged for purposes of illustration.

The protection product represented figure 1 comprises a support 1 of synthetic material, for example polystyrene, bearing a thin protective film 2 made of synthetic material, preferably transparent, an adhesive layer 3, a security printing 4 incorporated into reserves formed in the thickness of the adhesive layer 3, and a protective release paper 5 covering the adhesive layer 3.

The film 2 is, in the example shown, a multilayer film comprising two polyurethane layers 2a, 2b, interposed between them, an interleaving 6 of security reasons which may be authentication and / or anti- photocopying and / or anti-counterfeiting and / or anti-forgery or other. This film 2 can be manufactured by successive screen printing as described for example in EP-0271941 or US 5232527 directly made on the support 1 of polystyrene. The support 1 is a so-called non-adherent type of support, that is to say capable of developing only weak binding forces with most of the polymers. For example, it is a polystyrene sheet with a basis weight of about 120 g / m ² . This support 1 is chosen in a format exceeding that of the surface 8 of the object 9 to be protected. The film 2 may be manufactured by successive serigraphic printing on this support 1 by means of traditional screen printing machines of the cutter type (hinged screen) or of the type with integral lifting screen (moving screen in translation). The support 1 is placed on the plate of the screen printing machine and the screen thereof is lined with a liquid mixture previously prepared from a hydroxylated polyol and an isocyanate. (For example, polyacrylic resin "U 8560 reference" and trimerized hexamethylene diisocyanate "U 8580 reference" marketed by CHIMITEC Laboratories (FRANCE)).

The amount of mixture spread on the screen is adjusted according to the thickness that it is desired to obtain at each layer. The first layer 2a of continuous polyurethane varnish is thus printed in a format corresponding to that of the face 8 of the object 9 to be protected, for example rectangular in the case where the object is an official document such as a passport or a document. identity card having a rectangular face 8 to protect.

The support 1 and the first layer 2a are then left in the open air to allow the polymerization. Before the end of this polymerization, an intermittent interleaved printing forming patterns or frames on the first printing is carried out. This interleaving 6 can be made either from a traditional ink composition or even from an ink composition according to the invention incorporating a binder comprising at least one soluble liquid polar solvents and / or to nonpolar solvents as described below.

Before the complete polymerization of this intermediate printing 6 and the first layer 2a of polyurethane varnish, a subsequent printing is performed identical to the printing of the first layer 2a to obtain a second transparent polyurethane layer 2b.

A discontinuous security printing 4 is then carried out on the second layer of polyurethane varnish 2b, after a polymerization time of between 12 and 24 hours under the standard conditions of temperature and hygrometry. This time is determined so that the layer of polyurethane varnish 2b is both sufficiently partially polymerized to avoid any chemical interaction between this varnish 2b and the binder of the security printing 4, and nevertheless to allow the correct realization of the safety printing 4 on the varnish layer 2b (in particular avoiding screen smear phenomena). It should also be noted that the security printing 4 is carried out before the complete polymerization of the varnish layer 2b.

Transparent adhesive material is then produced in order to obtain the adhesive layer 3 by leaving reserves in the thickness of this adhesive layer 3 around the reasons of the security printing 4. Preferably, this adhesive layer is also produced. printing adhesive material 3 before the complete polymerization of the last layer 2b of the film 2.

In order to carry out security printing 4, an ink composition suitable for producing a screen printing, that is to say formed of a liquid solution with a viscosity of between 0.1 Pa.s and 100 Pa, is used. s -notably between 0.5 and 2.5 Pa. s-. This ink composition comprises at least one pigment, and a binder which is adapted to convey the pigment (s), and to form a solid, hard printing layer after drying.

Throughout the text, "binder" denotes any liquid composition adapted to be able to convey at least one pigment during a printing step, and to harden under curing conditions. According to the invention, the binder is of curable type by air drying.

This binder incorporates at least one agent, said soluble agent, which is distinct from a pigment, and which is adapted to dissolve at least under standard conditions of pressure temperature, that is to say under a pressure of order of one atmosphere (10 ⁵ Pa) and a temperature of the order of 23 ° C, in any polar and / or apolar liquid solvent capable of allowing the release of the adhesive when placed in contact with the adhesive after gluing. The amount of agent (s) soluble in the binder is adapted so that the security impression, solid and hard after drying, can form at least one visible task, revealing any attempt to detach with the help of at least one such solvent, when this solvent comes into contact with this solid security impression. Preferably, the soluble agent is also soluble in said solvents in a sufficiently wide pressure and temperature range around the standard conditions, in particular between 0.9 and 1.1 atmospheres (0.9 × 10 ⁵ Pa at 1.10 ° C. ⁵ Pa) and between 10 ° C and 30 ° C.

The (the) soluble agent (s) is (are) chosen (s) in particular according to the nature of the adhesive used to stick the film 2 on the face 8 of the object 9, which, itself, determines the families of liquid solvents that can be used by the fraudsters to effect a detachment after bonding the film 2 to the object 9.

It should be noted in this respect that, in general, the ink compositions, which are like varnishes, are, after curing, much less soluble in the polar and / or nonpolar liquid solvents than the adhesives. Consequently, there is a very large number of solvents which are capable of dissolving the adhesives after drying, without be able to dissolve the traditional ink compositions after drying. The incorporation of at least one soluble agent in the binder of an ink composition according to the invention thus makes it possible to make the security impression 4 at least as soluble, after drying, as the adhesive used to glue the film 2 on the face 8 of the object 9. It is therefore generally sufficient to incorporate a soluble agent which (i) has a high solubility in the majority of polar and / or apolar solvents, (ii) is compatible with the composition of ink and with its implementation to carry out the security printing 4, and (iii) does not dissolve in the adjacent layers (film 2 and / or adhesive 3 and / or face 8 of the object 9) during the manufacture of the protective product or when it is applied to an object 9 to be protected.

In general, the adhesives used in the protective products are acrylic resins or vinyl polyacetates (VAS) which have a relatively high solubility. In this case, advantageously, at least one soluble agent chosen from the group of alkyl acrylates, alkyl methacrylates, their polymers and copolymers is used. This group thus corresponds to that of vinyl compounds, in particular vinyl thermoplastic resins incorporating carboxylic ester functions, that is to say alkyl carboxylates. Preferably, the alkyl group of the carboxylate functions is an aliphatic alkyl comprising at least two carbon atoms. Indeed, the solubility of these vinyl compounds in many solvents, especially aliphatic hydrocarbon-based solvents, increases with the length of the alkyl chain, with the number of carboxylate functions, and, in the case of a polymer or a copolymer, with the degree of association between them monomer molecules (s).

Advantageously, isobutyl polymethacrylate is used as a soluble agent. Such a compound achieves an advantageous compromise by solvent-resistant adhesives based on acrylic or EVA but remaining soluble with a solubility similar to that of these adhesives in solvents likely to peel off these adhesives, including solvents based on aliphatic hydrocarbons.

More generally, it is advantageous to use, as soluble agent, at least one chemical compound having a low molecular weight-in particular less than 5000-, which will be soluble in the majority of polar and / or apolar solvents.

In the liquid ink composition used to form a security impression, this soluble agent may be solubilized in a solvent which is a volatile solvent (drying in ambient air or in hot air), for example propylene carbonate. . Said solvent is of the air-drying type insofar as a multicomponent or photopolymer or chemical drying solvent would be capable of generating compounds with long carbon chains which will not be subsequently soluble in the polar solvents and / or in the apolar solvents.

The binder of the liquid ink composition used to make a security impression may be formed of several different soluble agents that are in solution in the same solvent, or even a mixture of several liquid compositions each containing at least one soluble agent. which is in solution in a particular solvent (provided that the different solvents of the various liquid compositions are compatible in a mixture with each other). For example, it is possible to use a binder comprising a soluble agent with aqueous polar solvents (in particular with water), a soluble agent with non-aqueous polar solvents (especially with alcohols), and a soluble agent with apolar solvents (in particular with hydrocarbons). .

Many binder compositions incorporating one or more such soluble agents can be used. By way of example, it is possible to use a binder formed of a mixture of a reference solution "solubilis" marketed by Laboratoires CHIMITEC (FRANCE), which incorporates an isobutyl polymethacrylate and proves to be soluble to apolar solvents and nonaqueous polar solvents, and a so-called white liquid water fractioning solution, reference "889202" sold by the company SICPA (SWITZERLAND), which proved to be soluble in water and aqueous polar solvents. The binder can be formed from just one of these two solutions. It is thus possible to use each of these solutions in a proponion of 0% to 100% by volume.

The binder comprises a volatile solvent that can be used as a volatile solvent for the ink composition for performing security printing. The ink composition is then formed of the mixture of one or more binder (s) such (s) as mentioned above and one or more pigments.

• 60 à 65% de solvant volatile contenant au moins 10%
• notamment majoritairement- de carbonate de propylène,
• 5 à 25% de pigment(s) choisi(s) parmi les pigments visibles organiques, les pigments visibles minéraux, les pigments invisibles photoluminescents organiques, les pigments invisibles photoluminescents minéraux,
• 10 à 35% d'extrait sec de liant selon l'invention.

An example of an ink composition according to the invention is the following (the proposals being given in volume):

• 60 to 65% volatile solvent containing at least 10%
• especially mainly-propylene carbonate,
• From 5 to 25% of pigment (s) chosen from organic visible pigments, mineral visible pigments, organic photoluminescent invisible pigments, inorganic photoluminescent invisible pigments,
• 10 to 35% dry extract of binder according to the invention.

The binder may also comprise a non-zero proportion of agents other than soluble agents and their solvents, for example retarding agents, wetting agents, antifoaming agents, etc.

The amount of agent (s) soluble in the binder must be sufficient for the security printing 4 to dissolve and form a task visible to the eye when placed in contact with a solvent likely to dissolve the adhesive. It must also be weak enough to allow the implementation of the ink composition to achieve security printing 4.

Preferably, the solids content of the binder comprises a proportion of soluble agent (s), generally between 90% and 95% (volumes) such that, after drying, the printing layer formed by the Security printing 4 comprises at least 25% -in particular between 25% and 90% -of soluble agent (s).

The binder must also be adapted to be compatible with the pigment or the different pigments (distinct from the binder and thus from the soluble agent (s)) incorporated in the ink composition. As a pigment, it is possible to use one or more pigment (s) visible in visible light and / or one or more invisible pigment (s) under visible light and photoluminescent (s) under illumination by less a non-visible light source, for example a source of ultraviolet rays.

The security printing can be carried out in one or more passes, in particular to obtain colored patterns. The security printing can be of discontinuous type and have the form of a frame (formed of distinct points more or less tight, deposited in a uniform density or not), or patterns (images, signs, letters .... .). It can also be a uniform continuous type printing, extending opposite the entire surface of the film 2.

At the end of the polymerization and drying of the various layers 2a, 6, 2b, 3, 4, of the film 2, a multilayer complex product capable of being applied to an object 9 to be protected is obtained. The adhesive layer 3 and the security printing 4 are covered with a non-adhering protective sheet, for example, silicone removable paper. The whole product thus obtained can be stored and distributed without any particular precaution.

It should be noted that in this embodiment, the adhesive layer 3 can be formed from any adhesive composition. It may be in particular a pressure-sensitive adhesive (self-adhesive) such as an acrylic adhesive composition, in particular of the type sold by the Laboratoires CHIMITEC (FRANCE) under the reference "AD73EPSR" or a reactivatable adhesive to warm printed at room temperature compatible with the polyurethane varnish layer 2b, especially a thermoactivated adhesive formed of an aqueous dispersion copolymer such as an adhesive reference "ADTH50" or "ADTH21" marketed by Laboratoires CHIMITEC (FRANCE).

In the case of a self-adhesive, it is sufficient to take off the silicone paper 5, to apply the film 2 in contact with the face 8 of the object 9 to be protected ( figure 2 ) by exerting a pressure so as to stick the adhesive layer 3 on the face 8, then to take off the support 1 to obtain the protected object as shown figure 3 . In the case of a heat-activated adhesive 3, the support 1 is hot-rolled with the film 2 on the face 8 of the object 9.

As one can see figure 3 during a fraud attempt to peel the film 2 from the object 9, if a solvent S is injected at the periphery of the film 2 between the film 2 and the face 8 of the object 9, in in order to weaken the adhesive power of the adhesive 3 to peel the film 2 from the object 9, the soluble agents of the security printing binder 4 dissolve, and this security impression spreads and forms visible spots that can immediately reveal the fraud attempt. In addition, the security printing 4 is transferred to the object 9 which remains permanently marked thus revealing the fraud attempt and rendering it useless, since the object 9 itself is deteriorated. Nevertheless, the presence of the security printing 4 is not detectable in advance by observation of the object 9. In fact, nothing distinguishes a priori this impression of security of the other impressions traditionally used.

Preferably, a security print 4 is made at the periphery of the film 2 and in particular at its corners in the case of a rectangular film. It is indeed by the corners that fraud attempts are generally initiated.

The figure 4 represents a second embodiment of the product according to the invention, similar to that of the figure 1 , except that the adhesive layer 3 is a continuous layer extending over the entire surface of the film 2, and a security printing 4 is subsequently performed directly on this adhesive layer 3. To do this it is necessary that this layer of adhesive 3 is a layer of heat-sealable adhesive without "tac", that is to say without initial instant adhesion.

The third embodiment shown figure 5 differs from the previous in that the security printing 4 is performed first on the second layer 2b of polyurethane varnish, then the adhesive layer 3 is printed on top of the security printing 4. In this mode of In this embodiment, any adhesive layer 3 may be used, as in the case of the first embodiment.

It should be noted that although the adhesive compositions that can be printed by screen printing incorporate solvents, it is found in practice that it is possible to screen-print an adhesive layer 3 on a security printing 4 incorporating a soluble agent-in particular an isobutyl polymethacrylate-or, conversely, a security impression 4 on such an adhesive layer 3, without the binder of the ink composition according to the invention (incorporating at least one soluble agent) used for the security printing 4 does not dissolve in contact with the solvent of the adhesive layer, even when the binder of the security printing dissolves when it is subsequently brought into contact with a solvent as shown figure 3 .

No clear explanation of this surprising result can be given. It is nevertheless estimated that this printing possibility results from the screen printing process which does not generate shearing forces between the layer being printed and that on which this printing is performed. In this way, even if partial solubilization occurs between the two layers, it remains limited in thickness and, most importantly, does not generate any burr or visible task.

The embodiment of the figure 6 avoids, in cases where it is deemed necessary, contacting the security printing 4 with an adhesive before the film 2 is placed on the object 9. In this embodiment, a film is used. protection 2 similar to the one shown figure 1 and comprising a continuous adhesive layer 3, this film 2 being carried by a support 1 of polystyrene and the adhesive layer 3 being coated with a protective silicone paper 5. This product therefore constitutes a traditional product as described in EP-0271941 or US 5232527 .

Security printing 4 is carried out with an ink composition as described above (incorporating at least one pigment and a binder comprising at least one agent soluble in polar solvents and / or in apolar solvents) not on the film itself, but on the object 9, that is to say on the face 8 of the object 9 to protect. The film 2 is then applied to the face 8 by covering the security print 4 to obtain the protected object 9 as represented figure 7 .

The figure 8 represents another variant embodiment in which the security printing 4 is carried by the film 2, while the adhesive layer 3 is made on the face 8 of the object 9. Here again, the protected object 9 is obtained. which represents figure 9 which incorporates security printing 4.

In these last two variants, it is again surprisingly found that the binder of the security printing does not dissolve during the application of the adhesive 3 to the security printing 4, when the prints are made by serigraphy.

The figure 10 represents a fourth embodiment of the invention in which the protective film consists of a monolayer film, for example transparent polyester carrying a polyethylene layer 11 forming a heat-sealable adhesive. On this layer 11 of heat-sealable adhesive, a discontinuous security printing 4 was made by screen printing as described above.

The figure 11 represents a fifth embodiment in which a continuous security print 12 is directly made on a monolayer film of synthetic material such as polyester or polypropylene, and then this security print 12 is covered with a layer of adhesive 13 which may be a self-adhesive or a heat-sealable adhesive. This adhesive layer 13 is deposited by screen printing, as the security printing 12. The security printing 12 extends over the entire surface of the adhesive layer 13, at least substantially in the same format as the film This security impression 12 is made with an ink composition comprising at least one pigment and a binder comprising at least one agent soluble in polar solvents and / or in apolar solvents, as described above.

In this fifth embodiment, it is advantageous to use a visible pigment in visible light, but photoluminescent in invisible light, for example a photoluminescent pigment under ultraviolet. It is also possible to use one or more visible pigments.

The multilayer complex formed of the film 10, the adhesive layer 13 and the security printing 12 may be completely transparent (for example, a photoluminescent pigment under ultraviolet light) or translucent (in the case of a low-dose visible pigment) ) or opaque (case of a highly dosed visible pigment), depending on the intended applications. In the case of the application as a protection against falsification of variable inscriptions on official documents, the set must be transparent to allow the vision of said variable inscriptions to be seen normally. In the case of an application as authentication or guarantee of integrity of a document or a package, the complex may be translucent or opaque.

However, it is understood that it is preferable that the film 2, 10 is itself transparent so as to allow the visualization of the tasks resulting from the solubilization of the security printing 4, 12 in case of attempted fraud. However, this is not strictly necessary in certain applications where it is sufficient to detect fraud attempts only after the film has peeled off.

It should be noted that in the fifth embodiment, the adhesive layer 13 and the continuous security printing 12 may be associated not by screen printing, but by other printing methods, for example by rolling in continued.

In both embodiments of the Figures 10 and 11 , a non-stick protective paper 14 is also provided on the last layer of the protective product.

The figure 12 represents another variant embodiment in which security prints 15, 16 are made not on a protective film or on the object 9 to be protected, but on an intermediate film 17 formed of one or more layers of adhesive or Such an intermediate film 17 carried by its support 18 forms an intermediate sheet which can in particular be used for the realization of variable inscriptions, as described for example in FIG. FR-2763-889 . To produce this intermediate sheet, a security impression similar to that described above (incorporating at least one agent soluble in polar solvents and / or apolar solvents) is first made on the support 18, and then printed a first layer of varnish 17a covering the first security print 15, then a continuous layer of heat-activatable adhesive 17b is printed, then a second security print 16 is printed on said heat-activatable adhesive layer 17b. In the example shown, variable labels 19 were also printed by any desired printing means (manual, laser printing, inkjet printing, etc.).

The support 18 itself may be a paper and / or a monolayer synthetic film or multilayer non-adherent on most polymers, including a polystyrene support.

The object 9 to be protected initially bears, on its face 8 to protect, inscriptions 20. The protective film used in this variant may be a monolayer polyurethane film 22 produced by screen printing on a polystyrene support 21 with a continuous adhesive layer 23 such as described in EP-0271941 or US 5232527 . The adhesive layer 23 is nevertheless preferably formed of a heat-reactive adhesive.

To obtain the protected object 9 represented figure 13 the intermediate film 17 is hot laminated on the face 8 of the support 9 to be protected, then the support 18 is removed, then the film 22 is hot-rolled on this intermediate film 17, then the support 21 is removed. see, the security prints 15, 16 are interposed between the film 22 and the object 9.

The figure 14 represents an alternative embodiment similar to the figure 12 but in which the intermediate film 24 is formed of a single layer 24 of polyurethane varnish produced by screen printing on the support 18. A security impression 25 is then made on this intermediate film 24. A second security impression 26 is also performed on the adhesive layer 23 of the film 22. In addition, the object 9 to be protected carries a layer of adhesive 27 previously made on its face 8 in overlap of the inscriptions 20. The layers of adhesive 23, 27 in this variant embodiment may be pressure-sensitive self-adhesive or heat-activatable adhesives. To obtain the protected object of the figure 15 the intermediate film 24 is applied to the adhesive layer 27 of the object 9, the support 18 is removed, then the film 22 is applied to the intermediate film 24, then the support 21 is removed. Here again, the prints 25, 26 are interposed between the film 22 and the object 9.

In the embodiments of Figures 12 to 15 , the protection product according to the invention is formed in two parts: the film 22 on its support 21 and the intermediate film 17, 24 on its support 18. The security prints 15, 16, 25, 26 are not all realized on the film itself, but also on the support 18 of the intermediate film and / or on this intermediate film itself, which thus act as print media for these security prints. However, in all cases, the security prints are printed on printing media (film and / or intermediate film and / or film support or intermediate film) which are adapted to allow each print to be interposed. security 15, 16, 25, 26 between the film 22 and the object 9.

EXAMPLES

• produit 1 : conforme à la figure 1, de format rectangulaire de 80mm x 120mm, avec un film 2 d'épaisseur d'environ 45 µm,
• produit 2 : conforme à la figure 10 avec un support 10 en polyester de 50µm d'épaisseur et une couche d'adhésif thermoscellable en polyéthylène de 76µm d'épaisseur, de même format rectangulaire que le produit 1,
• produit 3 : conforme à la figure 11, le support 10 étant un polypropylène de 35µm d'épaisseur, et l'adhésif 13 étant un adhésif à base non aqueuse réf. L4002 de la société KISSEL ET WOLF (ALLEMAGNE) de même format rectangulaire que le produit 1,
• produit 4 : semblable au produit 3 mais avec un adhésif à base aqueuse réf AD73EPSR des Laboratoires CHIMITEC.

Four protection products are produced according to the invention having the following characteristics:

• product 1: conforms to figure 1 , rectangular format of 80mm x 120mm, with a film 2 approximately 45 μm thick,
• product 2: conforms to figure 10 with a support 10 made of polyester of 50 .mu.m thick and a layer of heat-sealable polyethylene adhesive 76 .mu.m thick, same rectangular format as the product 1,
• product 3: conforms to figure 11 , the support 10 being a polypropylene of 35 .mu.m thick, and the adhesive 13 being a non-aqueous based adhesive ref. L4002 from the company KISSEL ET WOLF (GERMANY) of the same rectangular format as the product 1,
• product 4: similar to product 3 but with a water-based adhesive AD73EPSR REF Laboratories CHIMITEC.

• solution "solubilis" commercialisée par les Laboratoires CHIMITEC (FRANCE) : 85%,
• pigment invisible fluorescent jaune ref. CD704 commercialisé par la société RIEDEL DE HAN (ALLEMAGNE) : 10 %,
• retardateur concentré commercialisé par les Laboratoires CHIMITEC : 5 %.

Security prints are made by screen printing in the form of guilloche patterns and letters on these products using an ink composition having the following formula:

• solution "solubilis" marketed by Laboratoires CHIMITEC (FRANCE): 85%,
• fluorescent invisible pigment yellow ref. CD704 marketed by the company RIEDEL DE HAN (GERMANY): 10%,
• concentrated retarder marketed by Laboratoires CHIMITEC: 5%.

Each protective product is glued on a security paper of 80g / m ² comprising 50% cotton and 50% wood, ref. PIC-TEST provided by ARJOWIGGINS APPLETOWN (FRANCE).

We then try to peel the film dry, hot or using various solvents. The following table gives the results obtained.

The invention can be the subject of numerous variants with respect to the embodiments and variants described above which can be combined with one another.

Claims (32)

1. Method for protection of an object in which a thin protective film (2, 10, 22) of synthetic material is glued onto a surface (8) of the object (9), by means of a layer of adhesive (3, 11, 13, 17b, 23, 27) interposed between the film (2, 10, 21) and said surface (8) and the object (9), in order to protect the object against falsifications and/or in order to authenticate it, and/or in order to guarantee its intactness, characterized in that, between the film (2, 10, 22) and the said surface (8) of the object (9), there is interposed at least one imprint, known as a security imprint (4, 12, 15, 16, 25, 26), produced by means of an ink composition comprising at least one pigment and a bonding agent which can be hardened by drying in air, said binding agent being designed to form a layer of imprint which is solid after it has dried, said binding agent incorporating at least one agent, called a soluble agent, which is designed to be dissolved, at least in standard conditions of temperature and pressure, after the bonding agent has dried, in any polar and/or non-polar liquid solvent, distinctive from a pigment and which can permit ungluing of the adhesive when it is placed in contact with this adhesive (3, 11, 13, 17b, 23, 27) after gluing, the quantity of soluble agent(s) in the bonding agent being designed such that the security imprint can form at least one stain which is visible, which reveals any attempt at ungluing by means of at least one such solvent.
2. Method according to claim 1, characterized in that at least one soluble agent is selected from amongst the acrylates of alkyls, the methacrylates of alkyls, their polymers and their copolymers.
3. Method according to claim 2, characterized in that a polymethacrylate of isobutyl is used as a soluble agent.
4. Method according to any one of claims 1 to 3, characterized in that an ink composition is used in which at least one soluble agent is formed from a chemical compound which has a low molecular weight, in particular lower than 5000.
5. Method according to any one of claims 1 to 4, characterized in that, in order to produce a security imprint (4, 12, 15, 16, 25, 26), a bonding agent is used which comprises a liquid solution, comprising a volatile solvent which dries in air, and at least one soluble agent.
6. Method according to any one of claims 1 to 5, characterized in that, in order to produce a security imprint (4, 12, 15, 16, 25, 26), a silk-screen ink base is used, comprising at least one agent which is soluble in solution, in a solvent containing at least 10% by volume of propylene carbonate.
7. Method according to any one of claims 1 to 6, characterized in that, in order to produce a security imprint (4, 12, 15, 16, 25, 26), use is made of a bonding agent comprising a diluting wash which is fugitive in water.
8. Method according to any one of claims 1 to 7, characterized in that a security imprint (4, 12, 15, 16, 25, 26) is produced on one surface of the film (2, 12, 22), which is then glued onto the object (9).
9. Method according to claim 8, characterized in that the film (2, 10, 22) is glued by means of a layer of adhesive (3, 11, 12, 17b, 23) which is previously imprinted onto the film (2, 10, 22).
10. Method according to claim 9, characterized in that a security imprint (4, 16) and an imprint of a layer of adhesive (3, 17b) are produced on a single surface of the film (2).
11. Method according to claim 10, characterized in that the layer of adhesive (3, 17b) and the security imprint (4, 16) are imprinted such that they do not overlap one another.
12. Method according to claim 10, characterized in that the layer of adhesive (3) is imprinted by silk-screen printing, covering a security imprint (4) previously produced.
13. Method according to claim 9, characterized in that a security imprint (4) is imprinted on a layer of adhesive (3) without initial instantaneous adhesion, previously produced on the film (2).
14. Method according to any one of claims 1 to 13, characterized in that a security imprint (4, 12, 15, 16, 25, 26) is produced by silk-screen printing.
15. Method according to any one of claims 1 to 14, characterized in that, in order to produce a security imprint (4, 12, 15, 16, 25, 26), at least one pigment is used, selected from amongst the pigments which are visible in visible light, and pigments which are invisible under lighting in visible light, and photoluminescent under lighting by at least one non-visible source of light.
16. Product for protection of an object, comprising a thin protective film (2, 10, 22) of synthetic material comprising a layer of adhesive (3, 11, 13, 17b, 23, 27) such that it can be glued onto a surface (8) of the object (9), in order to protect the object against falsifications and/or in order to authenticate it, and/or in order to guarantee its intactness, and a security imprint (4, 12, 15, 16, 25, 26), produced by means of a solid imprint composition comprising at least one pigment in a bonding agent, characterized in that it comprises at least one security imprint (4, 12, 15, 16, 25, 26) produced with a solid imprint composition comprising at least one pigment and a hardened bonding agent, said bonding agent incorporating at least one agent, called a soluble agent, distinctive from a pigment and which is designed to be dissolved, at least in standard conditions of temperature and pressure, in any polar and/or non-polar liquid solvent, which can permit ungluing of the adhesive when it is placed in contact with this adhesive (3, 11, 13, 17b, 23, 27) after gluing, the quantity of soluble agent(s) in the bonding agent being designed such that the security imprint can form at least one stain which is visible, which reveals any attempt at ungluing by means of at least one such solvent.
17. Product according to claim 16, characterized in that at least one soluble agent is selected from amongst the acrylates of alkyls, the methacrylates of alkyls, their polymers and their copolymers.
18. Product according to claim 17, characterized in that the bonding agent incorporates a polymethacrylate of isobutyl as a soluble agent.
19. Product according to any one of claims 16 to 18, characterized in that at least one soluble agent is formed from a chemical compound which has a low molecular weight, in particular lower than 5000.
20. Product according to any one of claims 16 to 19, characterized in that it comprises a discontinuous security imprint (4, 15, 16, 25, 26) in the form of a raster or patterns.
21. Product according to any one of claims 16 to 20, characterized in that it comprises a continuous security imprint (12), which extends opposite the entire surface of the film (10).
22. Product according to any one of claims 16 to 21, characterized in that the film (2, 10, 22) is selected from amongst a single-layer film, a multi-layer film comprising superimposition of layers imprinted by silk-screen printing, varnish and/or inks, and a multi-layer assembly of superimposed synthetic materials.
23. Product according to any one of claims 16 to 22, characterized in that the film (2, 10, 22) is formed from at least one synthetic material selected from amongst a polyurethane, a polyester, a polystyrene, a polypropylene and a polyethylene.
24. Product according to any one of claims 16 to 23, characterized in that the film (2, 10, 22) has an overall thickness of between 5 and 50 microns.
25. Object comprising a thin protective film (2, 10, 22) of synthetic material glued onto one (8) of its surfaces by means of a layer of adhesive (3, 11, 13, 17b, 23, 27) interposed between the film (2, 10, 22) and said surface (8) and the object (9), in order to protect the object against falsifications and/or in order to authenticate it, and/or in order to guarantee its intactness, characterized in that it comprises, interposed between the film (2, 10, 22) and the said surface (8) of the object (9), at least one imprint, known as the security imprint (4, 12, 15, 16, 25, 26), produced by means of a solid imprint composition comprising at least one pigment and a hardened bonding agent, said bonding agent incorporating at least one agent, known as a soluble agent, distinctive from a pigment which is designed to be dissolved, at least in standard conditions of temperature and pressure, after the bonding agent has dried, in any polar and/or non-polar liquid solvent, which can permit ungluing of the adhesive when it is placed in contact with this adhesive (3, 11, 13, 17b, 23, 27) after gluing, the quantity of soluble agent(s) in the bonding agent being designed such that the security imprint can form at least one stain which is visible, which reveals any attempt at ungluing by means of at least one such solvent.
26. Object according to claim 25, characterized in that at least one soluble agent is selected from amongst the acrylates of alkyls, the methacrylates of alkyls, their polymers and their copolymers.
27. Object according to claim 26, characterized in that the bonding agent incorporates a polymethacrylate of isobutyl as a soluble agent.
28. Object according to any one of claims 25 to 27, characterized in that at least one soluble agent is formed from a chemical compound which has a low molecular weight, in particular lower than 5000.
29. Object according to any one of claims 26 to 28 characterized in that a security imprint (4, 15, 16, 25, 26) is discontinuous, and has the form of a raster or patterns.
30. Object according to any one of claims 26 to 29, characterized in that a security imprint (12) is continuous, and extends opposite the entire surface of the film (10).
31. Object according to any one of claims 26 to 30, characterized in that the film (2, 10, 22) has an overall thickness of between 5 and 500 microns.
32. Object according to any one of claims 26 to 31, characterized in that a security imprint (4, 12, 15, 16, 25, 26) comprises at least one pigment, selected from amongst the pigments which are visible in visible light, and pigments which are invisible under lighting in visible light, and photoluminescent under lighting by at least one non-visible source of light.

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