Method of manufacturing a secure document with a mirror effect

Abstract

Method for manufacturing a secure document with a mirror effect The invention relates to a method for manufacturing a secure document with a mirror effect of smooth appearance unlike secure documents obtained using manufacturing methods known from the state of the art. Such a manufacturing method aims to improve the aesthetics and distinctive character of such a secure document. Figure for abstract: Fig. 1.

Description

Title of the invention: Method for manufacturing a secure document having a mirror effect Technical field

[0001] The present application belongs to the general field of secure documents. It relates more particularly to a method of manufacturing a secure document having a mirror effect as well as a secure document obtained by means of such a manufacturing method.

[0002] The invention finds a particularly advantageous application in the field of secure documents in the form of cards made from polymer materials such as, for example, payment cards or identity cards.

[0003] The invention may also be of interest in the field of business cards, loyalty cards or even gift cards in which the aesthetic appearance of these objects is particularly differentiating. Prior art

[0004] Conventionally, a secure document, such as a bank card, is made up of a plurality of layers stacked on top of each other. These layers, which can for example be made of different polymer materials, such as PVC (or polyvinyl chloride), PET (or polyethylene terephthalate) or PC (or polycarbonate), make it possible, in particular, to personalize and authenticate the secure document.

[0005] In order to modify the appearance of these secure documents to provide a distinctive aesthetic, it is known to use a metallic layer intended to create a mirror effect.

[0006] [Fig.l] represents such a secure document 10 seen from the front. The secure document 10 comprises on a first surface F1, at least one zone having a ZPEM mirror effect.

[0007] By way of example, the zone having a ZPEM mirror effect can cover the entire first surface F1 of the secure document 10. Alternatively, the zone having a ZPEM mirror effect can simply cover a limited zone of the first surface F1 of the secure document 10 as is the case in the representation given in [Fig.l].

[0008] The secure document 10 being in a substantially rectangular shape, a section plane II chosen parallel to a width of the secure document 10 is also shown in [Fig.l].

[0009] Generally, the secure document 10 comprises a plurality of layers visible in [Fig.2] which represents the secure document 10 according to the section plane II introduced with reference to [Fig.l].

[0010] More specifically, the secure document 10 comprises a substrate 11. In certain situations, this substrate 11 may comprise a near-field communication antenna such as an NFC antenna for “Near Field Communication”. This is particularly the case when the secure document 10 is a payment card or a transport ticket.

[0011] A first printable layer 12 is disposed on a first surface End of the substrate 11.

[0012] A metal layer 13 covers at least a portion of a surface Fi2 of the printable layer 12. Such a metal layer 13 is, for example, deposited by vaporization of metal particles on a portion of the surface Fi2 of the printable layer 12. The metal layer 13 may also be, in another example, a thin sheet of metal deposited on the surface F[2 of the printable layer 12.

[0013] Distinctive patterns, such as visuals, logos, trade names, trademarks, slogans, etc. can be printed on surface F[2 of the printable layer 12 as well as on a surface Fn of the metal layer 13.

[0014] In order to ensure the protection of the secure document 10 against any attempt at fraud and / or data theft or more simply to protect the secure document 10 against external attacks which could alter its appearance, the surface F[2 of the printable layer 12 and the surface Fn of the metal layer 13 are covered with a layer 14 of transparent polymer material.

[0015] A second printable layer 12' is arranged on a second surface F2n of the substrate 11. Such a printable layer 12' can also carry information relating to the holder of the secure document 10.

[0016] In order to ensure the protection of the secure document 10, the surface Fi2- of the printable layer 12' is also covered with a layer 14' of transparent polymer material.

[0017] Layers 11, 12, 13, 14, 12' and 14' are then hot laminated, thus sealing the secure document 10 and its contents.

[0018] The polymer material constituting the layers 14 and 14' being made up of monomer chains, the homogeneity of the polymer material can change following exposure to heat.

[0019] Indeed, during the hot rolling step leading to obtaining the secure document 10, the monomer chains constituting the polymer material begin to move under the effect of the heat, which leads to material displacements within the layers 14 and 14'. When this heat exceeds the glass transition temperature of the polymer material, the movements of the chains of monomers reach such an amplitude that in certain areas of layers 14 and 14' having more or less large surfaces, variations in the thickness of these layers 14 and 14' are created.

[0020] When the polymer material cools at the end of the rolling step, the metal layer 13 takes the shape of the surface of the layer 14 with which it is in contact, which generates the mirror effect. However, since the layer 14 has variations in thickness, the surface in contact with the metal layer 13 has imperfections, which leads to the appearance of an “orange peel” effect. In other words, instead of obtaining a mirror with a smooth appearance, an unattractive visual rendering is obtained as shown in [Fig. 3] in which the surface of the metal layer visible through the layer 14 has undulations.

[0021] There is therefore a need to propose a method for manufacturing secure documents having a mirror effect making it possible to reduce the “orange peel” effect. Statement of the invention

[0022] The present invention aims to remedy all or part of the drawbacks of the prior art, in particular those set out above, by proposing a solution which makes it possible to obtain a mirror having a smooth appearance.

[0023] To this end, and according to a first aspect, the invention relates to a method for manufacturing a secure document having a mirror effect, said secure document comprising at least: - a first layer of which a first surface is arranged on a substrate and a second surface is at least partially covered by a metal layer; - a second transparent polymer layer covering, at least partially, the second surface of the first layer and the metal layer; said manufacturing method comprising at least one hot laminating step during which the substrate, the first layer and the second layer are assembled to form the secure document, the first layer and the second layer being bonded together by means of an adhesive material.

[0024] Such a manufacturing method is particular in that: - the rolling temperature is less than or equal to the glass transition temperature of the transparent polymer constituting the second layer; - the average surface roughness of the adhesive material is less than 0.05 micrometers (pm); and - the average surface roughness of the surface of the second layer in contact with the metal layer is also less than 0.05 pm.

[0025] By not exceeding the glass transition temperature of the transparent polymer during the hot rolling step, the movement of material within the transparent polymer layer is limited. Thus, unlike what happens in the state of the art, the distribution of material remains homogeneous throughout the layer of polymer material. The latter therefore does not exhibit any variations in thickness.

[0026] By using a sheet of transparent polymer material having a very low average surface roughness, it is ensured that the surface of the layer of polymer material in contact with the metal layer is as flat and smooth as possible.

[0027] In order to preserve the smooth and flat appearance of this contact surface, the inventors of the present method propose to use an adhesive material which also has a very low average surface roughness. Thus, when the adhesive material melts under the effect of heat, it is distributed homogeneously on the surface of the metal layer, not creating variations in thickness.

[0028] Therefore, when the polymer material cools after the rolling step, the metal layer which takes the shape of the surface of the polymer material layer, has a smooth surface with little or no imperfections.

[0029] In particular embodiments, the transparent polymer material constituting the second layer belongs to the group comprising: - polycarbonate, - polyamide, - polyvinyl chloride, - polyethylene terephthalate.

[0030] In particular embodiments, the substrate comprises near-field communication means.

[0031] This is particularly the case when the secure document is a payment card or a transport card.

[0032] In particular embodiments, the adhesive material is an ink.

[0033] The adhesive material then fulfills a printable function of the secure document. This avoids adding additional material between the polymer material layer and the metal layer which could contribute to the appearance of an “orange peel” effect when the polymer material layer cools.

[0034] In particular embodiments, the ink is a transparent ink.

[0035] In particular embodiments, the adhesive material is a resin transparent.

[0036] In particular embodiments, the manufacturing method comprises, prior to the rolling step, a step of obtaining said second layer by rolling the transparent polymer between two rolling plates whose surfaces in contact with the polymer material have an average surface roughness of less than 0.05 pm.

[0037] Finally, according to a second aspect, the invention relates to a secure document having a mirror effect obtained by means of the manufacturing method according to any one of the implementations described previously. Brief description of the drawings

[0038] Other characteristics and advantages of the present invention will emerge from the description given below, with reference to the appended drawings which illustrate an exemplary embodiment thereof without any limiting character. In the figures:

[0039] [Fig.l] [Fig.l] represents a front view of a secure document comprising on a first surface, at least one zone having a mirror effect;

[0040] [Fig.2] [Fig.2] the secure document of [Fig.l] according to the section plane II introduced with reference to the latter;

[0041] [Fig.3] [Fig.3] represents a secure document obtained by means of a manufacturing process in accordance with state-of-the-art techniques, the secure document thus obtained has a mirror effect with an “orange peel” appearance;

[0042] [Fig.4] [Fig.4] represents a secure document obtained by means of the manufacturing method which is the subject of the invention, the secure document thus obtained has a smooth mirror effect. Description of the embodiments

[0043] The present invention provides a method for manufacturing a secure document having a smooth mirror effect unlike secure documents obtained using manufacturing methods known from the state of the art. This contributes to improving the aesthetics and distinctive character of such a secure document.

[0044] For the remainder of the description, it is considered in a non-limiting manner that the secure document 10 is a payment card as described previously with reference to [Fig. 1] and [Fig. 2].

[0045] In order to obtain a smooth mirror effect and thus reduce the “orange peel” appearance, the inventors of the present solution propose to apply several rules during the manufacture of this secure document 10 which will be described in more detail in the remainder of this document.

[0046] As already explained with reference to figures 1 and 2, the secure document 10 comprising: - a substrate 11, which may comprise in other implementations, a near-field communication antenna such as an antenna; - a first printable layer 12 placed on the first surface End of the substrate 11, - a metallic layer 13 covering, at least in part, a surface Fi2 of the printable layer 12; - a layer 14 of transparent polymer material covering, at least in part, the surface Fi2 of the printable layer 12 and the surface Fn of the metal layer 13; - a second printable layer 12' arranged on a second surface F2n of the substrate 11; and - a layer 14' of transparent polymer material covering, at least in part, the surface Fi2- of the printable layer 12'.

[0047] In order to obtain the smoothest possible mirror effect, a first rule consists of depositing a layer 14 of polymer material whose surface in contact with the surface Fi2 of the printable layer 12 and the surface Fn of the metal layer 13 has an average surface roughness less than or equal to 0.05 micrometers (pm).

[0048] By depositing a layer 14 having a very low average surface roughness, it is ensured that the surface of the layer 12 in contact with the surface F[2 of the printable layer 12 and the surface Fn of the metal layer 13 is as flat and smooth as possible.

[0049] A second rule consists of choosing an adhesive material which also has an average surface roughness of less than or equal to 0.05 pm.

[0050] By selecting an adhesive material having such a property, it helps to preserve the smooth and flat appearance of the surface Fn of the metal layer 13. Thus, when the adhesive material melts under the effect of heat during the rolling step, it is distributed homogeneously over the surface Fn of the metal layer 13 and does not create variations in thickness which could be the cause of an “orange peel” effect.

[0051] For example, the adhesive material may be an ink. It then fulfills a printable function of the secure document 10. Such an ink may, in certain cases, be a transparent ink.

[0052] In other implementations, the adhesive material is a transparent resin. Such a transparent resin may be, for example, a polyvinyl chloride copolymer, or vinyl acetate. It should be noted that other types of transparent resin may be used as long as they have an average surface roughness of less than or equal to 0.05 μm.

[0053] Finally, a third rule consists of not heating the rolling plates beyond the glass transition temperature of the polymer material constituting the layer 14.

[0054] Indeed, as already mentioned above in this document, the material polymer constituting layers 14 and 14' being made up of monomer chains, the homogeneity of this polymer material can change following exposure to heat.

[0055] By not exceeding the glass transition temperature of the transparent polymer during the hot rolling step, the movements of material within the transparent polymer layer are limited, which reduces the risks of variations in thickness of the polymer material appearing which could cause an “orange peel” effect.

[0056] By using a sheet of transparent polymer material having a very low average surface roughness, it is ensured that the surface of the layer 14 in contact with the surface Fi2 of the printable layer 12 and the surface Fn of the metal layer 13 is as flat and smooth as possible.

[0057] Thus, when the polymer material cools at the end of the rolling step, the metal layer 13 takes the shape of the surface of the layer 14 with which it is in contact, and consequently has a smooth surface with little or no imperfection.

[0058] The transparent polymer material constituting the layer 14 may be polycarbonate, polyamide, polyvinyl chloride or even polyethylene terephthalate.

[0059] Once the polymer material constituting the layer 14, 14' has been selected, it is necessary to adapt the temperature of the rolling plates so that the latter does not exceed the glass transition temperature of the chosen polymer material.

[0060] Thus when the polymer material chosen is polycarbonate, the temperature of the rolling plates must not exceed 150° Celsius (°C).

[0061] When the polymer material chosen is polyamide, the temperature of the rolling plates must not exceed 145°C.

[0062] When the polymer material chosen is polyvinyl chloride, the temperature of the rolling plates must not exceed 80°C.

[0063] And finally, when the polymer material chosen is polyethylene terephthalate, the temperature of the rolling plates must not exceed 240°C.

[0064] In a particular implementation, the manufacturing method comprises, prior to the rolling step, a step of obtaining the layer 14, 14' by rolling the transparent polymer constituting it between two rolling plates whose surfaces in contact with the polymer material have an average surface roughness of less than 0.05 μm. This ensures that the layer 14, 14' obtained meets the requirements of the second rule.

[0065] At the end of the laminating step of the manufacturing method which is the subject of the present invention, a secure document 10 is obtained having a smooth mirror effect such as this is shown in [Fig.4].

Claims

Claims

1. A method of manufacturing a secure document having a mirror effect, said secure document comprising at least: - a first layer of which a first surface is arranged on a substrate and a second surface is at least partially covered by a metal layer; - a second layer of transparent polymer covering, at least partially, the second surface of the first layer and the metal layer; said manufacturing method comprising at least one hot laminating step during which the substrate, the first layer and the second layer are assembled to form the secure document, the first layer and the second layer being bonded together by means of an adhesive material; and being characterized in that: - the laminating temperature is lower than the glass transition temperature of the transparent polymer constituting the second layer;- the average surface roughness of the adhesive material is less than 0.05 micrometers (pm); and - the average surface roughness of the surface of the second layer in contact with the metal layer is also less than 0.05 pm.;

2. Method for manufacturing a secure document having a mirror effect according to claim 1 in which the transparent polymer material constituting the second layer belongs to the group comprising: - polycarbonate, - polyamide, - polyvinyl chloride, - polyethylene terephthalate.

3. Method of manufacturing a secure document having a mirror effect according to one of claims 1 or 2 in which the substrate includes near-field communication means.

4. Method of manufacturing a secure document having a mirror effect according to one of claims 1 to 3 in which the adhesive material is an ink.

5. A method of manufacturing a secure document having a mirror effect according to claim 4 wherein the ink is a transparent ink.

6. Method for manufacturing a secure document having a mirror effect according to one of claims 1 to 3 in which the adhesive material is a transparent resin.

7. Method for manufacturing a secure document having a mirror effect according to one of claims 1 to 6 comprising, prior to the laminating step, a step of obtaining said second layer by laminating the transparent polymer between two laminating plates whose surfaces in contact with the polymer material have an average surface roughness of less than 0.05 μm.

8. Secure document having a mirror effect obtained by means of the manufacturing method according to any one of claims 1 to 7.

Images