FR2945551A1 - METHOD FOR MANUFACTURING A SECURITY ELEMENT FOR A SECURITY DOCUMENT - Google Patents

Abstract

A translucent zone (Z2) is formed in the element (14) by applying a product (24) that is transparent to its substrate (12). Thus, the method comprises a step of applying a product (20) impregnating the substrate (12) on a first zone (Z1) of a first face (F1) of the substrate surrounding a second zone (Z2) devoid of the product waterproofing (20). The waterproofing product (20) prevents the impregnation of the substrate (12) by the transparentizer (24) in the first zone (Z1). The method then comprises a step of applying the transparentizer (24) to at least the second zone (Z2) so as to impregnate the substrate (12) to make it translucent in this zone (Z2). The first (Z1) and second (Z2) zones respectively form first (18) and second (22) patterns composing an image observable from the two faces (F1, F2) of the substrate (12).

Description

The present invention relates to the technical field of security elements for document-value or security document. It applies more particularly to the manufacture of a security element of the type of transvision (in English see-through) that is to say comprising an image observable transmitted light or even reflected light in a translucent area d a substrate of the security element. In the field of securities documents, particularly banknotes, it is known to affix one or more security elements of various kinds to protect these documents from counterfeiting. There are different types of security elements, including so-called first-level security elements. Conventionally, a first level security element is difficult to achieve while being easily identifiable by any public during a simple observation. A transvision-type security element comprises a substrate on which complementary patterns are printed on each of its faces, arranged in a region of the substantially translucent or even transparent substrate, in register with each other so as to form a final composition observable in transmitted light, or even reflected light when the area is sufficiently translucent. The translucent zone allowing vision through also commonly referred to as transvision, is achieved for example by local modifications of the properties of the paper during its manufacture (density of fibers, basis weight, etc.). It is in particular known to form the translucent zone. on the substrate by application of a product that is transparent to the substrate.

In particular, it is already known from the state of the art, in particular from GB 1 489 084, a method of manufacturing a watermark in which a translucent zone is formed by applying a transparentizing composition. The disadvantage of this technique is that the wetting of the substrate gives a greasy and tacky appearance which impairs the aesthetics of the safety document even after drying. In addition, the transparentizing composition tends to migrate to the surface of the substrate which gives the translucent area a misshapen and irregular appearance having the appearance of an undesirable spot. The object of the invention is in particular to remedy this disadvantage by proposing a method of manufacturing a security element comprising a substrate provided with a particularly aesthetic translucent zone, while being very simple and inexpensive to implement. For this purpose, the subject of the invention is a method of manufacturing a security element for a security document, the security element comprising a substrate delimiting first and second opposing faces, in which a translucent zone is formed in the substrate by application of a product that is transparent to the substrate, characterized in that, to form this translucent zone, the method comprises a first step of applying a product which impregnates the substrate on a first zone of the first face surrounding a second zone of the first face devoid of this permeabilizing product, the waterproofing product preventing impregnation of the substrate by the transparent product in the first peripheral zone, then a second step of applying the transparentizing product to at least the second zone so as to to impregnate the substrate to make it translucent in this area, the first and second areas respectively forming first and second patterns composing an image observable from both sides of the substrate. The first zone forms a peripheral border around the second zone which prevents the impregnation of the substrate by the transparent product. Per device is an area that extends around the periphery of the second area. By transparency, we mean that renders translucent, even transparent. Of course, the first zone may comprise more or less complex nestings in the second zone, the important thing being that the contour of any part of the second zone is delimited by the first zone. The outline of the translucent zone can then be clearly delimited by virtue of the presence of the first zone which surrounds the translucent zone and which prevents, thanks to its previously applied waterproofing product, on the one hand, the transparent product from spreading beyond the limits of the second predefined zone and on the other hand to the transparent product to migrate in the substrate to the right of the first zone. This has the effect of reducing the diffuse aspect of the task. By waterproofing product is meant a product impervious to a liquid for at least a predefined period. Thus, when the transparentizing product is applied to an area of the substrate covered by the waterproofing product, the transparent product does not penetrate into the substrate at the right of this zone for a predefined period beyond which the effectiveness of the waterproofing product may decrease. . It is then necessary to dry the transparent product before the end of this predefined period so as to avoid a late impregnation of the transparent product in the substrate. Preferably, the waterproofing product is a product opaque to light and is thus said covering product. In this case, the two zones make up a contrasting image because of the presence of the two distinct products covering and transparency. The image observed in light reflected or transmitted from the first face comprises a dark zone corresponding to the first zone comprising the covering product and a clear zone corresponding to the translucent zone comprising the transparent product. By observing the image from the second face in transmitted or reflected light, this contrast is reversed. Indeed, the transparent product impregnates the substrate from the first face to the second face so as to form the second pattern on the second face.

Thus, the second pattern is perfectly observable from the second face in transmitted or reflected light. This second pattern is particularly detached from the uniform substrate by its diaphanous appearance related to the impregnation of the transparent product in the substrate.

On the contrary, the first pattern is difficult to observe from the second face since the substrate appears more opaque on the second face to the right of this area due to the presence of the covering product on the first side, in particular by observation in transmitted light. The image observable from the second face thus corresponds to the negative of the observable image from the first observation face, and this is clearly visible by observation in transmitted light. As a result, the first and second zones define between them a contrast in the image which is inversed as a function of the viewing face of the image.

Indeed, while by observation of the image from the first face (called front), the first pattern is more visible than the second pattern, this contrast is reversed by observation from the second side (called back) since since this face the first pattern is almost invisible (because of the opacity of the substrate in this area) while the second pattern is at least as visible as by observation from the first face (thanks to the impregnation of the substrate throughout its thickness). Preferably, the waterproofing product is an ink that can be used in offset printing, screen printing, flexography, letterpress, gravure and intaglio printing.

Preferably, the waterproofing product is an ink selected from an iridescent ink, a variable optical effect ink, a magnetic variable optical effect ink, a metal effect ink such as for example a silver ink and a liquid crystal ink. Preferably, the transparentizer is a high wetting ink comprising, for example, low surface tension monomers, resins and / or photoinitiators or acrylic ink.

Of course, the effectiveness of the impregnation of the substrate by the product depends not only on the characteristics of the transparent product (its wettability, its viscosity, the amount deposited and the time between the application of the product and its drying) but also the nature of the substrate (fiber impregnation capacity, basis weight, surface calendering, porosity, etc.). Preferably, the transparent product comprises security tracers, for example fluorescent particles, reaction type particles at a predefined wavelength and / or thermochromic particles.

Thus, thanks to the presence of such particles, optical effects and additional security can be obtained. Preferably, the method comprises a step of drying the product that is transparent by irradiation with ultraviolet or infrared spectrum light or by emission of a hot air stream. Thus, by drying, the transparent product is fixed on the substrate. Preferably, the substrate is made of a material essentially comprising paper based on natural and / or synthetic fibers, porous paper and / or paperboard. In addition, optionally and in one embodiment of the invention, the method comprises an intaglio printing step with a non-penetrating transparent ink or without ink to form a tactile mark in the second zone. This makes it possible to add a complementary effect to the composite image of the first and second patterns, thus producing tactile sensations.

Intaglio printing with ink allows to form a more pronounced relief detectable to the touch unlike the case where the substrate is difficult to deform. In the case of a deformable substrate, an intaglio print without ink (commonly referred to as dry stamp) may be sufficient to form a pronounced pronounced relief to the touch.

Preferably, the non-penetrating transparent ink comprises security tracers, for example fluorescent particles, reaction type particles at a predefined wavelength and / or thermochromic particles. In a manner known per se, the fluorescent particles react to exposure to ultraviolet light by producing a short-lived fluorescence reaction during this exposure. Typically, the thermochromic particles have a color that varies reversibly as a function of temperature. Preferably, the transparent product is applied to the substrate by screen printing, flexographic printing, offset printing, intaglio printing, letterpress and / or gravure printing. Furthermore, preferably, the method comprises a step of forming a third image pattern on the second face of the substrate in register with respect to the second zone so that it is observable from the first translucent face of the second zone. Alternatively, the third pattern 26 may not be formed in registration but in free positioning relative to other patterns. Preferably, the third pattern completes the first and second patterns to form a final image observable from both sides in transmitted light, or even even reflected light.

In addition, in one embodiment of the invention, the third pattern comprises a message coded on the second face and the second zone comprises means for decoding the message able to reveal the message encoded by observation from the first face of the message. less in transmitted light.

Preferably, the second inner zone is made sufficiently translucent to allow observation in reflected light from one of the faces of the substrate of a third pattern extending on the other of the faces in register with respect to the inner zone. . Thus, the transvision effect can also be observed in reflected light and this facilitates verification of the authenticity of the security document, in particular, in cases where the person verifying does not particularly have the time or skills to check this authenticity.

The invention also relates to a security element, characterized in that it is obtained from a manufacturing method according to the invention. The invention finally relates to a security document, such as a bank note, comprising a security element, characterized in that the security element is according to the invention. Other characteristics and advantages of the invention will emerge in the light of the description which follows, made with reference to the appended drawings, in which FIGS. 1A and 1B respectively represent top and bottom views of a security document comprising a security element according to a first embodiment of the invention; Figs. 2A and 2B respectively show top and bottom views of a security document comprising a security element according to a second embodiment of the invention according to section 3-3 of Fig. 2A; Figure 3 shows a sectional view of the security document of Figures 2A and 2B; Figs. 4A and 4B show respectively top and bottom views of a security document comprising a security element according to a third embodiment; Figs. 5A and 5B show respectively top and bottom views of a security document comprising a security element according to a fourth embodiment; FIGS. 6A and 6B respectively represent top and bottom views of a security document comprising a security element according to a fifth embodiment in orthogonal observation with respect to the plane of the security document and FIGS. 6C and 6D represent the same views as FIGS. 6A and 6B but in grazing observation; Figures 7 to 10 illustrate steps of a method of manufacturing a security document comprising a security element according to a sixth embodiment.

FIGS. 1A and 1B show a security document comprising a security element according to the first embodiment. This security document is designated by the general reference 10. The security document 10 comprises a substrate 12 defining first F1 and second F2 opposite faces. In this example, the security document 10 is a page of a passport. Alternatively, the security document 10 may be a bank note or other valuable document. This security document 10 comprises a security element 14 formed on a portion of the substrate 12. This security element 14 comprises a first zone Z1 forming a first pattern 18 extending on the first face F1 of the substrate 12. This first pattern 18 is formed by a deposition of a waterproofing product 20. Preferably, the waterproofing product 20 is also opaque to light and is designated in the following description by product covering 20. Of course, alternatively, the waterproofing product 20 may to be more or less opaque, even translucent, without this outside the scope of the invention. For example, the covering product 20 is applied to the substrate 12 by screen printing, flexography, offset and / or intaglio printing, by typography and / or heliography. Thus, preferably, the covering product 20 is an ink that can be used in offset printing, flexography, screen printing, letterpress, gravure and intaglio printing. Further, the covering product 20 is preferably an ink selected from an iridescent ink, a variable optical effect ink, a magnetic variable optical effect ink, a metal effect ink, such as silver ink and a crystal ink. liquids. On the other hand, the security element 14 comprises a second zone Z2 forming a second pattern 22 and devoid of the covering product 20. This zone Z2 is translucent, that is to say that it lets the light pass. This second zone Z2 is formed by applying a transparent product 24. Optionally, the transparent product 24 is applied beyond the second zone Z2, partly on the first zone Z1.

Indeed, more particularly, the covering product 20 prevents the impregnation of the substrate 12 by the transparent product 24 in the first zone Z1. For example, the transparentizer 24 is a high wetting ink comprising low surface tension monomers, resins and / or photoinitiators or acrylic ink. Thus, for example, a suitable transparentizing product comprises a composition such as that described in GB 1 489 084. Preferably, the transparent product 24 is applied by screen printing. Alternatively, the transparent product 24 may be applied by any other known printing technique. The first zone Z1 is hereinafter referred to as peripheral as opposed to the second zone Z2, referred to as the internal zone, since the zone Z1 surrounds said second zone Z2, referred to as the internal zone. In this first embodiment, the first zone Z1 has a generally oval shape and the second zone Z2 has a general shape of a flower. In the example described, the security element 14 comprises a third pattern 26 printed on the second face F2 of the substrate 12. This third pattern 26 completes the image formed by the first 18 and second 22 20 patterns. The third pattern 26 extends over a third zone Z3 of the substrate 12. This third pattern 26 is printed on the outside with respect to the first 18 and second 22 patterns. The image obtained is observable from the two faces F1, F2 of the substrate 12 in transmitted light and at least partially in reflected light. Preferably, the second zone Z2 is made sufficiently translucent to allow observation in reflected light from both faces F1, F2. Thus, the inner zone Z2 is sufficiently translucent to allow observation of the third pattern 26 in reflected light and not only light transmitted from the first face FI (as can be seen in FIG. 2A).

Indeed, the first pattern 18 of the image resulting from the application of the covering product 20 is observable without difficulty in light reflected from the first face F1 but is more difficult to observe in light reflected from the second face F2.

Thus, the contrast between an area of the substrate 12 devoid of any product and the zone Z1 is relatively low because the substrate 12 outside the zone Z2 is relatively opaque in observation from the face F2. The first and second zones Z1, Z2 define between them a contrast in the image which is inversed as a function of the observation face F1, F2 of the image in transmitted light, or even in reflected light in the case where the second internal zone Z2 is sufficiently translucent. However, while the contrast is relatively clear in light observation transmitted from the two faces F1, F2, the latter is less visible when the image is observed from the second face F2 (ie say the face F2 not carrying the covering product) in reflected light. FIGS. 2A to 6B show second to fifth embodiments of a security document 10 comprising a security element 14. In these embodiments, elements similar to the first embodiment have identical references to the figures and in the description. These various embodiments make it possible to increase the security level of the document carrying the security element. In the second embodiment illustrated by FIGS. 2A and 2B, the first zone Z1 also extends partly in the center of the second zone Z2. The first zone Z1 following the contours of the second zone Z2.

Moreover, in this embodiment, the third pattern 26 is partially printed in the second translucent zone Z2. Preferably, the second zone Z2 is made sufficiently translucent to allow observation in reflected light from the face F1 of a third pattern 26 extending on the face F2 in registering on the outside and on the inside relative to in the second zone Z2. It is visible by observation in reflected light from the two faces FI, F2 of the substrate 12.

In Figure 3, there is shown the layers of material applied to the substrate 12 to form the zones Z1, Z2 and Z3. Thus, the zone Z1 comprises a layer of covering product 20, zone Z2 comprises a layer of transparent product 22 which impregnates the substrate 12 over its entire thickness without impregnating the substrate 12 at the zone Z1. Finally, zone Z3 also comprises a product layer 28 such as an ink. In the third embodiment illustrated by Figures 4A, 4B, the security document 10 is a bank note. The security element 14 has for example a generally rectangular shape forming a vertical band in the ticket 10. The security element 14 comprises a first band-like peripheral zone Z1 and a second translucent inner zone Z2 delimiting a second pattern 22. In the example illustrated in the figures, the second pattern 22 comprises twice the number '100' inverted and a stylized sun. The zone Z3 represents a third pattern 26 and comprises the number `100 'at the place whose central number' 0 'forms a sun complementing the sun in the face F1 of the substrate 12. In the fourth illustrated embodiment in FIGS. 5A, 5B, the third pattern 26 comprises a coded message 30 on the second face F2 and the second zone Z2 comprises means 32 for decoding the message capable of revealing the coded message 30 by observation from the first face F1 at least in transmitted light. In this example, it can be seen that the third pattern 26 is a scrambled message OA which is difficult to perceive with the naked eye while observing transmitted and / or reflected light from the second face F2 of the substrate 12. On the other hand, by observation from of the first face F1, thanks to the presence of the decoding means in the zone Z2, the message 30 is revealed by transvision. The message 30 is encoded for example by a known steganography technique which consists of coding information in a background by point variations, for example by lines modulated at a predefined frequency. The third pattern 26 is preferably made by offset printing.

The decoding means 32 comprise for example lines modulated at a frequency substantially equal to the frequency of concealment of the message. Preferably, the lines are printed and / or formed in relief. In this illustrated example, the decoding means 32 comprise a relief 31 forming a repetition of lines of predefined height and frequency substantially identical to that used for coding the message. This relief 31 is for example produced by the vector of the embossing technique. The dry stamp is made in register with respect to the offset printing of the face F2 of the substrate 12 and forms a steganographic decoding pattern, to reveal the hidden data on the second face F2 of the substrate 12. For example, the relief 31 is made by intaglio printing with a non-penetrating transparent ink to also form a tactile mark in the second zone Z2.

The non-penetrating transparent ink preferably comprises security tracers, for example fluorescent particles, reaction type particles at a predefined wavelength and / or thermochromic particles. Figs. 6A and 6B show a security document 10 comprising a security element 14 according to a fifth embodiment of the invention. In this fifth embodiment, the third pattern 26 comprises at least one latent image 34 on the first face F1, in particular in the first zone Z1. In particular, it can be seen that the letters B and C form first 34A and second 34B latent images. The third pattern 26 comprises a third latent image 34C formed on the second face F2, in the second zone Z2. These latent images 34A-34C are formed by deformation with or without ink. Conventionally, a latent image is obtained by intaglio printing and is visible only at a certain inclination of the document, for example in grazing observation. Depending on the angle of view, the image appears with more or less contrast with the background.

In the example described, the latent images are produced by a printing process in relief. The security element 14 comprises a first network of lines 36 extending in a predefined orientation and a second network of lines 38 extending in another orientation, for example oblique (as in the example shown) or perpendicular, forming and a clear break between the two networks 36 and 38. For example, the second network 38 forms a latent image pattern that may include information (in this example, the information includes letters B and C) and the first network. 36 forms the bottom of the latent image. Thus, as can be seen in FIGS. 6A and 6B, in orthogonal observation we do not see the latent image but in grazing observation as illustrated in FIGS. 6C and 6D, the pattern of the latent image clearly appears.

The main steps of a method of manufacturing a security document 10 comprising a security element 14 will now be described with reference to FIGS. 7 to 10. The reasons for the security element 14 illustrated by these figures have forms different from the patterns of the other embodiments but the manufacturing method is applicable for the realization of the security element of any of the previously described embodiments. Initially and optionally, the third pattern 26 of the image delimited by the third zone Z3 is formed on the second face F2 of the substrate 12. This third zone Z3 is formed by printing of the flexographic type, intaglio, screen printing, typography or heliogravure, but preferably in offset. The third pattern 26 represents a sun inscribed in a star. The third pattern can be printed in many colors. Then, during a second step illustrated in FIG. 8, the zone Z1 is formed on the first face F1 of the substrate 12 by application on the zone Z1 of a product covering 20. This first zone Z1 has an oval shape delimiting inside a second zone Z2 devoid of covering product.

During a third step illustrated in FIG. 9, the transparent product 24 is applied to at least the internal zone Z2 so as to impregnate the substrate 12 to make it translucent in this zone. The first Z1 and second Z2 zones respectively form first 18 and second 22 patterns complementing each other to form an observable image at least by transmitted light and preferably by reflected light from the two faces FI, F2 of the substrate 12. As the zone Z1 comprises covering product 20 which prevents the impregnation of the substrate 12 by the transparent product 24, it is possible to substantially overflow the first zone Z1 during this application without this overflow is visible. During this step, when the transparent product 24 has impregnated the substrate 12 over its entire thickness, the third pattern 26 appears in transmitted light, or even in light reflected by observation from the first face F1. The method further comprises a step of drying the transparent product 24 by irradiation irradiation with ultraviolet or infrared spectrum light or by emission of a hot air stream. Applying the transparent product 24 overflowing over the first zone Z1 only slightly changes the appearance of the covering product 18 on the first face F1. Indeed, it is possible to observe a slight change in the golden appearance of the product covering 18 if the latter is an iridescent ink for example. Thus, it is possible that the application of the transparent product 24 to the covering product may slightly tarnish its golden appearance. This also makes it possible to produce new additional optical effects. It is understood that the embodiments which have just been described are not limiting and that they can receive any desirable modification without departing from the scope of the invention.

In particular, it would be consistent with the invention to apply the transparent product by any other printing technique than those mentioned preferentially in the description.

Claims (17)

REVENDICATIONS1. A method of manufacturing a security element (14) for a security document (10), the security element (14) comprising a substrate (12) delimiting first (F1) and second (F2) opposite sides, wherein forming a translucent zone (Z2) in the substrate (12) by application of a product (24) that is transparent to the substrate (12), characterized in that, to form this translucent zone (Z2), the method comprises a first step application of a product (20) waterproofing the substrate (12) on a first zone (Z1) of the first face (FI) surrounding a second zone (Z2) of the first face (F1), without this waterproofing product (20), the waterproofing product (20) preventing the impregnation of the substrate (12) with the transparent product (24) in the first zone (Z1), and then - a second step of applying the transparent product (24) onto the least the second zone so as to impregnate the substrate (12) for the ren translucent dre in this zone (Z2), the first (Z1) and second (Z2) zones respectively forming first (18) and second (22) units constituting an image observable from the two faces (F1, F2) of the substrate ( 12). 2. Method according to the preceding claim, wherein the waterproofing product is opaque to light. 3. The method of claim 1 or 2, wherein the waterproofing product (20) is an ink used in offset printing, flexography, screen printing, letterpress, gravure and intaglio. A method according to any one of the preceding claims wherein the waterproofing product (20) is an ink selected from an iridescent ink, a variable optical effect ink, a magnetic variable optical effect ink, a metallic effect ink and a liquid crystal ink. A method according to any one of the preceding claims wherein the transparentizer (24) is a high meltable ink comprising, for example, low surface tension monomers, resins and / or photoinitiators or acrylic ink. . 6. Method according to the preceding claim, wherein the transparentizer (24) comprises security tracers, for example fluorescent particles, reaction type particles at a predefined wavelength and / or thermochromic particles. 7. Method according to any one of the preceding claims, comprising a step of drying the transparentizer (24) by irradiation with ultraviolet or infrared spectrum light or by emission of a hot air flow. A method according to any one of the preceding claims comprising an intaglio printing step with a non-penetrating or inkless transparent ink to form a tactile mark in the second zone (Z2). 9. Method according to the preceding claim, wherein the non-penetrating transparent ink comprises security tracers, for example fluorescent particles, reaction type particles at a predefined wavelength and / or thermochromic particles. 10. A method according to any one of the preceding claims, wherein the transparentizer (24) is applied to the substrate (12) by screen printing, flexography, offset, intaglio printing, typography and / or gravure. 11. Method according to any one of the preceding claims, comprising a step of forming a third pattern (26) of the image on the second face (F2) in register with respect to the second zone (Z2) so as to what is observable from the first side (FI) by translucency of the second zone (Z2). 12. Method according to the preceding claim, wherein the third pattern (26) completes the first (18) and second (22) patterns to form a final image observable from both sides (F1, F2). The method according to the preceding claim, wherein the third pattern (26) comprises an encoded message (30) on the second face (F2) and the second area (Z2) comprises means (32) for decoding the message able to reveal the coded message (30) by observation from the first face (F1) at least in transmitted light. A method according to any one of the preceding claims, wherein the substrate (12) is made of a material comprising essentially natural and / or synthetic fiber-based paper, porous paper and / or paperboard. A method according to any one of the preceding claims, wherein the second zone (Z2) is made sufficiently translucent to allow observation in reflected light from one of the faces (F1) of a third pattern (26). extending on the other faces (F2) in register with respect to the second zone (Z2). 16. Security element (14), characterized in that it is obtained from a manufacturing method according to any one of the preceding claims. 17. Security document (10), such as a banknote, comprising a security element (14), characterized in that the security element (14) is according to the preceding claim.