Security document comprising a transparent window

Abstract

The invention relates to a security document comprising a body made up of at least two transparent plastic substrates (12a, 12b) and bounded by edges (16) forming a substantially rectangular surface comprising four corners, wherein at least one of the substrates (12a, 12b) receives a printing layer (20) that is opaque in the visible spectrum and is applied up to the edges (16) of the document (10). The printing layer (20) defines a peripheral portion (24) that is at least partially free of printing and forms a set of lines bordering a secure zone (27) containing security information, wherein the peripheral portion (24) has a minimum dimension free of printing of between 100 µm and 500 µm, such that the plastic substrates (12) are in direct contact and bonded together in the peripheral portion (24).

Description

[0001] Security document with a transparent window

[0002] The invention relates to the field of security documents such as contact or contactless smart cards or cards without a chip, made of a plastic material, and which may have different formats specified in the standards (to be specified). For example, these formats are called ID1 (bank card format), ID2 which corresponds to double ID1 (French national identity card format), and ID3 (passport format).

[0003] The invention relates particularly to security documents comprising a printing layer possibly forming one or more transparent windows.

[0004] Security documents comprising windows by cutting a cavity in a printed card body and then adding a transparent insert into the cavity are known from the prior art. Patent EP3389963 describes such a security document, and in particular the manufacturing method used to produce it on mass production lines. Inserting a transparent insert or pellet remains a costly and complex process to carry out due to the difficulty of automatically inserting said insert.

[0005] It is also known from the prior art US10909334 to produce a window by filling a cavity, previously cut in an opaque central layer, with a plastic material resulting from the deformation of the two transparent substrates positioned below and above the central layer. Indeed, the deformation of the substrates is caused by the application of pressure and a high temperature during lamination. When the glass transition temperature is reached, the plastic material becomes viscous and fills the cavity formed in the opaque substrate. Upon cooling, the plastic material returns to a solid state and then forms the transparent window of the security document.

[0006] However, this solution has the disadvantage of leaving, on the surface of the document, a mark corresponding to the area of ​​the transparent window, in particular a mark of the material flow area.

[0007] It is also known from the prior art to produce transparent windows by producing an area devoid of printing. For this purpose, a transparent substrate is provided on which a printing layer is deposited. The printing layer is applied over the entire surface of the substrate, with the exception of an area delimited to form the window. The assembly of this substrate with one or more other transparent layers makes it possible to form a security document that is opaque in the area where the printing layer is deposited and transparent in the area delimiting the window.

[0008] However, this solution has a major drawback when the plastic substrate is made of polycarbonate. Indeed, polycarbonate has very poor adhesion properties with other materials. Thus, after laminating a polycarbonate substrate with another polycarbonate substrate covered with a printing layer, the adhesion properties at the interface of the printed layer and the polycarbonate substrate remain poor.

[0009] To date, there is no ink compatible with polycarbonate that guarantees perfect cohesion between the polycarbonate layers and the ink of the printing layer. It is therefore necessary to limit the ink coverage rate to a maximum of 30-40% of the surface of the substrate so as to avoid the risks of delamination due to a lack of cohesion between the layers or to seal the card 30 with transparent edges 32 of 3 mm to secure and protect the elements of the identity documents as illustrated in Figure 1. However, this last option restricts the possibilities of patterns, compatibility with security elements, such as laser engraving, other prints or even the insertion of holograms and does not meet customer demands.

[0010] There are therefore one or more disadvantages to using the prior art solutions when the security document must be observed as an opaque document with the exception of the window area. Printing the ink then involves a coverage rate of 100%, creating a risk of delamination at the interface between the ink and the polycarbonate substrate. This therefore induces a major risk of fraud and durability on the security document. It is then possible to attack the document from its edges and recover security elements.

[0011] The invention proposes to remedy this drawback.

[0012] To this end, the invention proposes a security document comprising a body composed of at least two transparent plastic substrates and delimited by edges forming a substantially rectangular surface comprising four corners, at least one of the substrates receiving a printing layer opaque in the visible range and applied to the edges of the document, the printing layer delimiting a peripheral part at least partially devoid of printing forming a set of lines bordering a secure zone containing security information, the peripheral part having a smaller dimension devoid of printing of between 100 pm and 500 pm, so that the plastic substrates are in direct contact and assembled in the peripheral part.

[0013] Thanks to these provisions, the documents have a printed layer over their entire surface with the exception of a peripheral part, such as a very thin strip, also called a groove, without printing. This very thin strip without printing, embedded in the printing pattern, allows contact between the two plastic substrates and thus ensures a more robust assembly between the different substrates constituting the document and avoids separation of the different layers constituting the document. In addition, this very thin strip allows a greater possibility of patterns, compatibility with security elements, such as laser engraving, other printing or even the insertion of holograms, thus meeting customer requests. According to other characteristics: the peripheral part is completely without printing;the peripheral portion is partially devoid of printing by forming devoid of printing ridges separated by printed edges; the ridges and edges have substantially the same smallest dimension; the secure area bordered by the peripheral portion represents 90% of the surface of the document; the secure area bordered by the peripheral portion represents less than a quarter of the surface of the document and includes a security element such as an engraved portrait, a printed portrait, a diffractive element; the thickness of the printing layer being between 5 pm and 50 pm; the devoid of printing peripheral portion forms a continuous pattern forming a loop on the surface of the document or a continuous pattern between two edges of the document; the devoid of printing peripheral portion forms a discontinuous pattern;the discontinuous pattern is formed by the association of four peripheral zones each formed in the vicinity of the four corners of the document and extending substantially parallel to the edges; the printing layer delimits an area devoid of printing so as to create a transparent window in the security document; the plastic substrates are polycarbonate substrates.;

[0014] Figure 1 represents a security document according to the prior art,

[0015] Figure 2 represents a front view of a security document according to the invention, Figure 3 represents a sectional view of a security document according to the invention, Figure 4 represents a detailed view of a security document according to the invention following an attempted delamination,

[0016] Figure 5 represents a curve illustrating the force applied during the delamination of a document according to the invention, up to the breaking point,

[0017] Figures 6a and 6b represent two examples of patterns of a security document produced according to the invention.

[0018] Figure 7 represents a document according to a variant of the invention, Figure 8 represents a document according to another variant of the invention. The invention relates to identity documents 10 and more particularly to documents of ID-1 format corresponding to the format of a smart card as specified in the ISO7816-1 standard, as illustrated in Figure 2. The invention also applies to other formats such as that of a plastic page integrated into a passport.

[0019] These documents 10 are used to receive data relating to the identity of individuals and are therefore likely to be fragmented in order to recover security elements constituting them or to create fraudulent security documents. This consists in particular of separating the layers constituting the document, to recover security elements with the aim of reintroducing them into false documents. It is therefore important that the reproduction or falsification of this type of document remains very difficult, if not impossible.

[0020] The documents generally consist of several (at least two) plastic substrates assembled together after a lamination step in which the substrates are pressed between two lamination plates at high temperature, for example 200°C. Figure 3 illustrates a security document 10 consisting of two substrates 12a, 12b made of plastic, preferably polycarbonate.

[0021] The two substrates 12a, 12b are assembled to form the document 10 which has a first outer face 14a and a second outer face 14b opposite the first outer face 14a. In the remainder of the description, the first and second faces 14a, 14b will be called respectively the upper face 14a and the lower face 14b of the document 10, according to the conventional observation of these documents 10. The document 10 is further defined by four edges 16 having a thickness of the document 10 and extending between the upper 14a and lower 14b faces. The edges 16 have a very thin thickness, less than 1 mm and together delimit the contour 18 of the document 10. The document 10, and consequently the two substrates 12a, 12b, have the same contour 18.The contour is defined during cutting by the following manufacturing method: the plastic substrates 12a, 12b are first assembled together to form an intermediate product of several substrates 12a, 12b, this intermediate product is then cut to the desired format to obtain the final document 10 of contour 18. As indicated further on, the document 10 has a format specific to identity documents, namely a bank card or passport format. The document 10, and consequently the two substrates before lamination, therefore each have a contour 18 delimiting a rectangular surface and formed by four sides connected to each other by four corners respectively.

[0022] Generally, at least one of the two substrates 12a receives a printing layer 20, for example an ink or a varnish, which forms a decorative pattern or even personalization data relating to the cardholder. This printing layer 20 is located at the interface of the two plastic substrates 12a, 12b, after lamination of the security document, as illustrated in FIGS. 2 and 3. This printing layer 20 is deposited on the substrate 12a by printing techniques known to those skilled in the art, namely inkjet printing, offset printing or screen printing. The color of the printing layer 20 is chosen according to the preselected pattern, and the density of pigments coloring the ink is determined in advance according to the desired opacity and shade.The printing layer 20 is applied over an entire surface of the substrate 12a, that is to say up to the contour (or edges) of said substrate 12a, with the exception of an area intended to form a transparent window 22, in association with the other substrates 12b of the document 10, and with the exception of a peripheral part 24 which will be described in more detail in the remainder of the description.

[0023] The printing layer 20 has a very thin thickness of 5 to 50 μm. Despite its thin thickness, the printing layer 20 makes it possible to obtain sufficient opacity so that a user cannot see through the printing layer 20 under ambient lighting. The printing layer 20, deposited using techniques mastered by those skilled in the art, makes it possible to produce varied shapes and graphics with great freedom at a lower cost. This simple and inexpensive technique for producing a window 22 has a considerable advantage compared to the technique of cutting and placing a transparent insert mentioned further on in the description.

[0024] The area without printing forming the transparent window 22 allows the user to observe different information. This may be, for example, a pattern engraved in the thickness of the transparent window 22, such as a secondary portrait, or even a hologram, positioned between two substrates and the color of which varies according to the lighting to which the document 10 is subjected.

[0025] However, depending on the nature of the ink of the printing layer 20, there are adhesion incompatibilities with plastic substrates 12a, 12b and particularly with polycarbonate substrates 12a, 12b. To date, no ink is known that allows strong and durable adhesion with a polycarbonate substrate. This generates a real security risk for the documents 10 which can then be separated into several elements, to then be reused in fraudulent documents.

[0026] The invention aims to remedy this problem by producing a peripheral part 24 devoid of printing, partially or totally. To this end, the peripheral part 24 devoid, at least partially, of printing forms a set of lines bordering a secure zone containing security information. Thus the plastic substrates 12 are in direct contact and assembled in the peripheral part 24 which borders said secure zone.

[0027] The peripheral part has a smaller dimension without printing between 100 and 500 pm. This smaller dimension is for example the width of a narrow strip.

[0028] In this peripheral portion 24, the two substrates are in contact and bonded by chemical and physical adhesion after the lamination step.

[0029] Indeed, during lamination, the plastic substrates 12a, 12b will undergo an increase in temperature beyond the glass transition temperature. Their state is then modified so that the surface material of one substrate 12a softens and has melting and adhesion properties with the other surface of the second substrate 12b having undergone the same transformations. In this case, when two polycarbonate substrates 12a, 12b are laminated together, the surfaces at the interface of the two substrates 12a, 12b have sufficient transformation to create strong cohesion of material of the two substrates 12a, 12b. This cohesion is present over the entire peripheral portion 24 and it is then made very difficult to separate the two substrates 12a, 12b without damaging them.

[0030] This effect is demonstrated by the diagram of Figure 4 and by the curve of Figure 5 illustrating the mechanical behavior of the elements constituting the security document of Figure 2. When a malicious user attempts to separate the substrates 12a, 12b from the document 10, the adhesion force of the printing layer 20 is lower than that allowing the removal of the removed substrate. It is therefore possible to begin to separate the first substrate 12a from the second substrate 12b covered with the printing layer 20. This is illustrated by the first part of the curve of Figure 5 representing a substantially constant and low tearing force. However, in the peripheral part 24 without printing, the force necessary to separate the substrates 12a, 12b increases sharply as illustrated in Figure 5 by the sudden increase in the curve forming a peak representing the force necessary to separate the two substrates at the peripheral part 24.This separation force, which is an elastic tensile force applied to the substrate 12a, increases until it reaches the breaking threshold of the polycarbonate substrate 12a.

[0031] It therefore becomes impossible to separate, intact, the two polycarbonate substrates 12a, 12b, because this operation results in the irreversible tearing of at least one of the two substrates 12a, 12b in the peripheral part 24 devoid of printing. The two substrates 12a, 12b are then rendered unusable for falsifying or manufacturing a fraudulent document.

[0032] In order to prevent the separation (or peeling) of the substrates constituting a document, it is important that this peripheral portion 24 extends between one or more edges 16 of the document and the secure area to be protected, close to the secure area to be protected. According to a first embodiment illustrated in Figures 2, 6a and 6b, the peripheral portion 24 is formed of at least four peripheral zones 24a, 24b, 24c, 24d each formed in the vicinity of the four corners of the document 10 and extending substantially parallel to the sides of the document 10. The four peripheral zones 24a, 24b, 24c, 24d are arranged close to the four corners of the card to ensure strong adhesion between the plastic layers at the corners which are likely to be an area of ​​initiation of delamination of the different substrates 12a, 12b constituting the document 10.The peripheral portion is made very thin, between 100 pm and 500 pm, and is difficult to see with the naked eye for an observer and moreover leaves a majority of the surface of the substrate 12a, 12b available for the printing layer 20. Each of the four peripheral zones 24a, 24b, 24c, 24d is positioned close to a corner, at a distance less than 5% of the length of the side forming the corner. This offers the advantage of guaranteeing the impossibility of separating the substrates 12a, 12b beyond this distance. Thus the central part of the document 10, forming the secure zone, is preserved due to the sealing between the plastic substrates 12a, 12b at the peripheral portion 24, in particular at the peripheral zones 24a, 24b, 24c, 24d. It is not possible for a fraudster to gain access to the security elements positioned in this central part forming the secure zone from the edge of the document 10.

[0033] In Figures 2 and 3, the peripheral portion 24 forms a continuous pattern represented by the four peripheral zones 24a, 24b, 24c, 24d connected to each other. The four peripheral zones 24a, 24b, 24c, 24d are arranged near the four corners of the card to ensure strong adhesion between the plastic substrates at the corners which are likely to be a zone of initiation of delamination of the different layers of the card. The peripheral portion 24 without printing 20 can have different shapes which will be described below.

[0034] According to a first embodiment, illustrated by figures 2 to 6 and 8, the peripheral part 24 is completely devoid of printing. The adhesion between the plastic substrates 12a, 12b is thus achieved over the entire length and width of the peripheral part 24. This can be a continuous line parallel to the edges of the document as visible in figure 2.

[0035] According to a second embodiment, illustrated in Figure 7, the peripheral portion 24 is partially devoid of printing by forming ridges 26 devoid of printing separated by printed edges 28. The smallest dimension without printing is then formed by the width of the ridges 26 and is between 100 pm and 500 pm. The adhesion between the two substrates is therefore achieved on the cumulative surfaces of the ridges 26. Advantageously, the ridges 26 and the edges 28 have substantially the same smallest dimension, so that the adhesion between the substrates is achieved on at least half of the surface of the peripheral portion. Figure 7 illustrates a peripheral portion 24 partially devoid of printing extending to the edges 16 of the document 10. This embodiment has the advantage of being aesthetic, of presenting continuity with the printing carried out in the central zone of the card.Moreover, this method is relatively easy to carry out because printing is a process that allows numerous designs to be produced without great technical difficulty.

[0036] According to an alternative embodiment visible in figures 2, 6a, 6b the secure zone bordered by the peripheral part presents 90% of the surface of the document. Indeed in these alternative embodiments, the peripheral part 24 extends near the edges 16 of the document 10, or up to the edges 16 of the document 10. As explained previously, the central part of the document 10, forming the secure zone, is preserved due to the sealing between the plastic substrates 12a, 12b at the peripheral part 24. It is therefore not possible for a fraudster to have access to the security elements positioned in this central part.

[0037] In the embodiment illustrated in Figure 7, there are two secure areas 27a, 27b each bordered by a peripheral portion. The first secure area 27a represents 90% of the surface of the document, and the second secure area 27b represents less than a quarter of the surface of the document and comprises a security element 29. In Figure 7, the security element 29 is a printed portrait, but it could be an engraved portrait or even a diffractive element.

[0038] According to another variant, the peripheral part 24 forms a continuous pattern such as a loop forming a closed loop visible in figure 2 or even a continuous pattern between two edges 16 of the document 10, as illustrated in figure 8.

[0039] Figures 6a and 6b represent two examples of graphics of peripheral parts 24 without printing of a document 10 produced according to the invention.

[0040] Unlike figures 2 and 3, the embodiments of figures 6a to 6b illustrate a discontinuous peripheral part 24 represented by the association of the four peripheral zones 24a, 24b, 24c, 24d separated from each other by printing zones and are arranged near the four corners of the card to ensure strong adhesion between the plastic layers at the location of the corners which are likely to be a zone of initiation of delamination of the different layers of the card. Each of the four peripheral zones 24a, 24b, 24c, 24d is positioned near a corner, at a distance equal to 5% of the length of the side forming the corner.

[0041] In Figure 6b, the four peripheral areas 24a, 24b, 24c, 24d form a figurative ornamental pattern, for example the outline of a country.

[0042] In Figure 6a, the four peripheral areas 24a, 24b, 24c, 24d form an abstract ornamental pattern; the four peripheral areas are grouped in pairs to form a partially discontinuous peripheral portion 24.

[0043] The invention also relates to a method for manufacturing a security document. This method comprises the steps of providing at least two transparent substrates, such as polycarbonate substrates. Then, a printing step is carried out on one face of one of the two substrates by applying a printing layer delimiting a transparent peripheral portion 24 and possibly a transparent window 22. The two substrates are then assembled by lamination, so that the printing layer is located at the interface of the two substrates and the two substrates can come into contact in the area of ​​the window and the peripheral portion.

Claims

Claims

1. Security document comprising a body composed of at least two transparent plastic substrates (12a, 12b) and delimited by edges (16) forming a substantially rectangular surface comprising four corners, at least one of the substrates (12a, 12b) receiving a printing layer (20) opaque in the visible range and applied up to the edges (16) of the document (10), the printing layer (20) delimiting a peripheral portion (24) at least partially devoid of printing and forming a set of lines bordering a secure zone (27) containing security information, the peripheral portion (24) having a smallest dimension devoid of printing of between 100pm and 500pm, so that the plastic substrates (12) are in direct contact and assembled in the peripheral portion (24).

2. Document according to the preceding claim, in which the peripheral part (24) is completely devoid of printing.

3. Document according to claim 1 in which the peripheral part (24) is partially devoid of printing by forming streaks (26) devoid of printing separated by printed edges (28).

4. Document according to the preceding claim, in which the striations (26) and the edges (28) have substantially the same smallest dimension.

5. Document according to one of the preceding claims, in which the secure zone (27) bordered by the peripheral part (24) presents 90% of the surface of the document (10).

6. Document according to one of the preceding claims, in which the secure zone (27) bordered by the peripheral part (24) represents less than a quarter of the surface of the document (10) and comprises a security element (29) such as an engraved portrait, a printed portrait, a diffractive element.

7. Document according to one of the preceding claims, in which the thickness of the printing layer (20) is between 5 pm and 50 pm.

8. Document according to one of the preceding claims, in which the peripheral part (24) devoid of printing forms a pattern continuous forming a loop on the surface of the document or a continuous pattern between two edges of the document.

9. Document according to one of claims 1 to 7, in which the peripheral part (24) devoid of printing forms a discontinuous pattern.

10. Document according to the preceding claim, in which the discontinuous pattern is formed by the association of four peripheral zones (24a, 24b, 24c, 24d) each formed in the vicinity of the four corners of the document (10) and extending substantially parallel to the edges (16).

11. Document according to one of the preceding claims, in which the printing layer (20) delimits an area devoid of printing so as to create a transparent window (22) in the security document.

12. Document according to one of the preceding claims, in which the plastic substrates (12a, 12b) are polycarbonate substrates.

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