EP2494398A1

EP2494398A1 - Security element comprising an adhesive and a substrate bearing an optical structure, and associated method

Info

Publication number: EP2494398A1
Application number: EP10782704A
Authority: EP
Inventors: Michel Camus; Stéphane Mallol; Pierre Doublet
Original assignee: ArjoWiggins Security SAS
Current assignee: ArjoWiggins Security SAS
Priority date: 2009-10-30
Filing date: 2010-10-28
Publication date: 2012-09-05
Also published as: BR112012010078A2; FR2952193A1; WO2011051905A1; CA2779636A1; FR2952193B1; US20120281294A1

Abstract

The invention relates to a security element (1) which comprises a substrate (6) bearing at least the following elements on at least one of the faces thereof, namely: an optical structure (4) producing at least one image of at least one pattern (5) and/or producing image points of a light source illuminating the optical structure; and an adhesive (14), in particular a heat-sealable varnish, covering at least part of the aforementioned face of the substrate (6) without fully covering the optical structure (4).

Description

Security element comprising an adhesive and a substrate carrying an optical structure, and associated method

The present invention relates to security elements, in particular those intended to be introduced in security documents.

"Security document" means a means of payment, such as a bank note, a check or a restaurant ticket, an identity document, such as an identity card, a visa, a passport or a driving license, a lottery ticket, a ticket or a ticket for cultural or sporting events.

In order to guard against attempts to falsify or counterfeit a security document, it may be useful for the authentication and / or identification of a security element to be simple.

It is known to make security elements with lenticular arrays associated with specific impressions, in order to produce movement, depth and / or stereoscopic effects. The SECURENCY company markets under the MOTION ^® brand.

Such security elements exploit an optical structure whose face is exposed to the air, so that the difference between the refractive indices of the air and the material of the structure produces the desired refraction of the light rays.

The optical effects obtained using the use of lenticular arrays have in particular been described in the article "The History of Integral Print Methods" extracted from "Lenz Array Print Techniques" by David E. Roberts and Trebor Smith, the article "The moiré magnifier" by MC HUTLEY et al, 1994 IOP publishing ltd., and the publication "Academy of the Sciences", of the Session of March 2, 1908.

It is also known from publications US 3,241,429, US 3,154,872,

US 3,576,089, US 4,645,301, US 4,892,336, US 6,833,960, WO 94/27254, WO 2005/052650, US 6,856,462, US 2005/184504, US 5,708,871, WO 2005/058610. , US 2005/150964, US 2009/008923, WO 2007/020048, and WO 2009/017824 various optical structures.

Lenticular arrays have been used in the prior art to allow their superposition to printed patterns so as to generate motion effects during the observation, in particular by magnifying moiré effects. US 7,497,475 and WO 2007/133613 describe security documents comprising optical structures, on which prints are directly made.

Furthermore, publications WO 2005/052249, JP 2008-063685, JP 2008-063684, EP 1 704 537, EP 1 567 713, EP 1 442 171, GB 2 311 303, US 5 783 275, EP 1 141 are known. 480, EP 1 872 965, EP 1 887 134, EP 0 319 157, EP 2 082 097, WO 96/39685, US 5 405 500, EP 0 609 252 and EP 0 059056 methods for incorporating security elements. in security documents, with an adhesive to facilitate their incorporation.

The application of an adhesive to optical structures of a security element may, however, have the drawback of deteriorating the observation properties of the optical structures due to the presence of the adhesive on their surface.

There is a need for security features having an optical structure that can be effectively incorporated into a security document while retaining the visual properties of the optical structure.

The invention thus has, according to one of its aspects, a security element comprising a substrate bearing on at least one of its faces at least:

an optical structure, in particular an optical structure producing at least one image of at least one pattern and / or producing image points of a light source illuminating the optical structure,

an adhesive, in particular a heat-sealable varnish, at least partially covering said substrate face without completely covering the optical structure.

The optical structure may completely cover the face of the substrate carrying the optical structure, or alternatively cover it only partially.

The aforementioned pattern can be used to generate at least one image that can be compared to a reference pattern in the context of an authentication for example. This reason is called in the following reason of comparison, even if its role is purely decorative and / or playful.

By "without completely covering", it is necessary to understand without covering the optical structure at all or covering it but not entirely. The absence of adhesive covering the optical structure completely may make it possible not to affect the observation properties of the optical structure in the part or parts not covered by the adhesive

The adhesive can improve the adhesion of the security element to a security document.

The adhesive may completely cover the area (s) of the face of the substrate not covered by the optical structure when the latter only partially covers the face of the substrate carrying it.

The adhesive can at least partially cover both sides of the substrate. The two faces of the substrate may or may not each carry an optical structure. The adhesive can completely cover one side of the substrate without an optical structure.

The adhesive may be transparent, translucent or opaque. The adhesive can be heat sealable. The adhesive may be colorless or colored, visible to the naked eye, under ultraviolet (UV) and / or infrared (IR), fluorescent, phosphorescent, thermochromic, photochromic, among others.

The adhesive disposed on one side may be colored, and associated with a substrate or a second adhesive disposed on the other side having another coloring. In particular, when the adhesive on the one hand and the susbstrate or second adhesive on the other hand have different fluorescent dyes, an effect similar to that described in application FR 2 877 609 is obtained.

The adhesive may form a pattern corresponding, for example identical, or complementary to the comparison pattern and / or the reference pattern. Said adhesive is in particular visible under UV and / or IR illumination, fluorescent or phosphorescent.

The adhesive may for example be a heat-sealing coating, for example a heat-sealing varnish, an ultraviolet (UV) cross-linkable agent, an adhesive to be irradiated, a pressure-sensitive adhesive (PSA), a varnish with a solvent base, of the type polyester for example, an adhesive in the aqueous phase, etc.

As adhesive in the aqueous phase that may be used, mention may be made especially of the following marks: Mowilith DC (aqueous dispersion of homopolymeric vinyl acetate with particles of size ranging from 0.3 μιη to 2 μιη and glass transition temperature T _g of About 38 ° C., and dry content of solids between 55 and 57%) and Vinamul 3265 from CELANESE; DH9004, DH9017, DH9044 and the DL5001 from COLLANO; Primai NW1845, Primai LC40, Primai P308M and Primai EP6000 from ROHM &HAAS; the 006SDW078-2 from BASF.

The adhesive may advantageously be an adhesive based on polyvinyl acetate such as Mowilith DC.

The incorporation of the adhesive into the security element can be by coating or printing.

The coating can be performed before or after formation of the optical structure on the substrate.

The coating may be carried out on one side of the substrate or on both sides of the substrate. The adhesive can completely cover one side of the substrate.

The adhesive may cover a reference pattern carried by one of the faces of the substrate, in particular the face carrying the optical structure.

Optical structure

The optical structure may have an outer surface, that is to say, facing the observer, non-planar.

The optical structure may or may not extend from one edge to another of the substrate depending on the length and / or the width of the substrate.

The substrate may have one or more areas devoid of the optical structure and one or more areas covered by the optical structure.

The optical structure can be discontinuous. In particular, the optical structure may consist of a set of disjoint optical substructures, identical or not. These optical substructures may comprise elementary optical structures, for example lens arrays, these elementary optical structures may or may not be disjoint and may or may not be identical.

The adhesive may cover in particular the area or areas of the face of the substrate not covered by the elementary optical structures.

The optical structure may be reflective or not. Alternatively, it may be partially reflective, for example semi-reflective.

The optical structure may have an elongate shape along a longitudinal axis. The optical structure may have any geometric shape, for example a polygonal or non-polygonal contour, for example square, rectangle, rhombus, triangle, trapezium, parallelogram, circular, elliptical, among others.

The elementary optical structures constituting the optical structure may or may not all have the same geometrical shape. The elementary optical structures may for example all be in the form of parallelograms. The elementary optical structures, identical or not, may be arranged on the security element at regular intervals or not.

The optical structure may comprise a network of lenses of a thickness for example between 2 and 30μιη, for example equal to 6μιη, and a lens diameter for example between 10 and ΙΟΟμιη, for example equal to 20 μιη.

The optical structure may have a surface, reflective or not, of at least partially spherical shape, optionally truncated, polyhedral, in particular pyramidal, with an optionally truncated apex, among others. The optical structure may further include a Fresnel lens.

The optical structure can be made by embossing, in particular by thermo-embossing or by embossing followed by crosslinking with ultraviolet, or by molding. The optical structure may further comprise a printed lenticular network comprising lenses which may or may not be juxtaposed, for example by UV printing, for example by screen printing, gravure printing, letterpress printing or by inkjet printing.

The optical structure can be made by screen printing, gravure printing, flexography and offset printing.

The optical structure may comprise a concave, convex or Fresnel lens, a lenticular array or else a resin or varnish print, for example crosslinkable by ultraviolet rays.

In the case of a reflective optical structure, the optical structure may consist of elementary optical structures in the form of mirrors arranged in a regular network, in one or more directions.

In the case of a reflective optical structure, the reflecting surface of the optical structure can be made by metallization of a non-planar surface, which makes it possible to benefit from a continuous reflecting surface while the embossing of a film of a transparent substrate covered on one side with a layer of metal would be likely to break the surface of the metal and lead to the formation of unsightly cracks and / or can make the optical structure partially inoperative.

The aforementioned mirrors may in particular be formed by the metallization of a lenticular array, a non-planar face of the array being preferably metallized after manufacture of this array, to avoid breaking the metal layer, as explained above. The mirror or mirrors may be of different types, for example concave, convex, cylindrical, parabolic, spherical or aspherical. Within the network, all the mirrors can be identical or not.

The at least partially reflective optical structures can also be obtained by producing a Fresnel lens receiving a metallization.

In exemplary embodiments of the invention, the at least partially reflective optical structure (s) is concave to one or more patterns formed on the substrate to produce at least one enlarged image of the pattern (s), and to observe more easily the pattern or patterns, despite their small size.

The optical structure, for example the aforementioned lenticular array may be formed on the substrate, in the same material or not, whether or not reported. The lenticular optical structure can be made for example by printing or embossing.

The thickness of the substrate is for example between 5 and 100 μιη, preferably 20 and 30 μιη. The substrate may have a constant thickness. The thickness of the substrate may optionally be chosen as a function of the optical structure, for example as a function of the focal length of this optical structure, so as to have the desired optical effect.

The aforementioned optical structure can be made so that the associated comparison pattern is between the substrate and the optical structure. In this case, the thickness of the substrate may not substantially modify the visual result obtained.

The optical structure may cover one side of the substrate and the one or more comparison patterns may be formed thereon on the opposite side. In this case, the choice of the thickness of the substrate makes it possible to bring the comparison pattern closer to or away from the optical structure, and may make it possible to adapt the distance of the comparison pattern to the optical structure as a function of the focal length. of it.

The lenticular network may comprise an array of spherical mirrors, for example concave towards the substrate. In examples of implementation of the invention, the radius at the top of a mirror, especially when it is concave to a pattern formed on the substrate, may be between 30 and 45 μιη. The distance between the apex of the mirror and the adjacent face of the substrate is for example between 10 and 20 μιη, for example between 14 and 16 μιη. The pattern associated with the mirror can be entirely located in the concavity of the mirror. The diameter of the mirror, at its face adjacent to the substrate, is for example between 50 and 70 μιη, for example between 58 and 62 μιη.

The aforementioned optical structure can be metallized by a vacuum metallization technique, the metal used being, for example, aluminum.

The security element may comprise optical structures of different types.

The optical structure may comprise non-planar elementary reflecting surfaces, for example concave or convex, of which a small dimension, in particular the height, is for example greater than or equal to 20 μιη, for example 30 μιη.

The optical structure may be covered, preferably partially, with at least one inactivation varnish of the optical structure, canceling the optical effect (s) obtained by the optical structure. This inactivation varnish has for example a refractive index equal to or sufficiently close to that of the optical structure for the optical structure to cease to produce its effects. The inactivation varnish may be transparent, colored or not.

The presence of an inactivation varnish on the optical structure can thus make it possible to create one or more zones without optical effect on the optical structure, making it possible to see, where appropriate, a pattern underlying the optical structure without magnification effect. by the optical structure.

The inactivation varnish may be superimposed on a reference pattern carried by the substrate, for example carried by the face of the substrate opposite to the face carrying the optical structure. In this way, the presence of the inactivation varnish canceling the optical effect (s) of the optical structure can make it possible to observe the reference pattern through the optical structure without this observation being affected by the optical structure. The observation of the reference pattern through the optical structure covered with such an inactivation varnish can in particular correspond to the observation of the reference pattern that would be made directly without the presence of the optical structure. The mactivation varnish may have a refractive index, for example greater than that of air. The refractive index of the mactivation varnish may for example be the same as the refractive index of the optical structure, in particular of the zone of the optical structure on which the mactivation varnish is applied. The refractive index of the mactivation varnish can generally be chosen so that it makes it possible to cancel the optical effect (s) obtained by the optical structure.

The mactivation varnish can for example be applied to the optical structure by a printing process.

The outer surface of the mactivation varnish may be adapted to cancel the optical effect (s) obtained by the optical structure. It can preferably be flat.

The mactivation varnish and the heat-sealing varnish may form one and the same varnish.

Alternatively, the security element comprises heat-sealing varnish and mactivation varnish present in distinct form. The mactivation varnish can then be placed between the security element and the heat-sealing varnish.

The optical structure can completely cover the face of the substrate which carries it and include a mactivation varnish canceling in places the optical effect (s) of this optical structure. In this way, the manufacturing method of the security element can be simplified. For example, from a substrate bearing on at least one of its faces an optical structure completely covering said face, the manufacturing method may comprise the step of forming one or more reference and / or comparison patterns. , in particular by printing, on the substrate and applying a varnish of mactivation of the optical structure on the substrate, in particular on a face of the substrate opposite to the face carrying the reference and / or comparison pattern, the patterns of reference and / or comparison and the mactivation varnish being applied in a marked manner.

The use of a mactivation varnish as described above can in particular be done when the optical structure has one or more optical effects from non-flatness between the ambient air and the optical structure, especially when the optical structure comprises a lenticular network. The inactivation varnish of the optical structure may be partially or completely covered with an adhesive as described above, in particular a heat-sealable varnish.

The adhesive as mentioned above may, where appropriate, be an inactivation varnish, canceling the optical effect (s) obtained by the optical structure.

Motiffs)

The substrate may carry at least one reference pattern, the optical structure and the reference pattern being carried by the substrate to allow the simultaneous observation of at least one image given by the optical structure and the reference pattern.

One of the images given by the optical structure may correspond substantially to the reference pattern.

By "substantially corresponding" is meant in particular that the simultaneous observation of the optical structure and the reference pattern makes it possible to apprehend a similarity between the images observed or a complementarity. In particular, at least one of the images given by the optical structure and the reference pattern may resemble, complement or superimpose at least partially, better completely, for example corresponding to the same alphanumeric character, sign, logo, symbol , character or object. In the case of complementarity, at least one of the images of the comparison pattern produced by the optical structure may be the symbol of a currency while the reference pattern will be the encrypted amount corresponding to the security document.

The invention can thus make it possible to authenticate and / or identify in a simplified manner an object, in particular a security document, comprising a security element as described above, in particular by observing the similarities existing during the observation. between at least one of the images given by the optical structure and the reference pattern.

In addition, the invention can make it possible to obtain a simplified manufacturing security element that can easily be incorporated into a security document by providing the same substrate with a reference pattern and an optical structure. may, if necessary, be superimposed on a comparison pattern carried by the substrate.

The reference pattern can give a still image, especially regardless of the angle of view. The reference pattern and / or the comparison pattern may consist of at least two elementary patterns respectively reference and / or comparison.

The reference pattern can be observed independently of the optical structure. It may in particular be located outside the zone comprising said optical structure.

The substrate may carry at least one comparison pattern, the optical structure being superimposed on this comparison pattern.

The optical structure can produce at least one enlarged or unmagnified image of the comparison pattern. The magnification may for example be greater than 1.5, better 2, better 3, for example between 1.5 and 5. High magnifications will be used especially in the case where the pattern, or the elementary patterns, associated with ) to the optical structure, are of very small dimensions. The high magnifications will be obtained for example by magnifying moiré effect, as described in the previously cited literature.

The optical structure can give a moving image, in particular an image whose dimensions are variable, an image appearing and disappearing, or more generally a changing image, of one or more pattern (s) as a function of the angle of observation. . In the case of a movement effect, the amplitude of the movement will be all the more important as the magnification rate is high. At least one of the images of the comparison pattern may for example correspond substantially to the reference pattern, so that a user can observe both the reference pattern independently of the viewing angle and a moving image for the reference pattern. comparison pattern according to the angle of observation.

The comparison pattern may be arranged, in particular with respect to the optical structure, to allow the observation of at least one 2D or 3D image.

The comparison pattern can in particular use the Moiré magnifying principle to restore a depth effect or an impression of movement. It may also include at least one image produced by interlacing at least two images, for example to restore, during a change of the viewing angle, an animation or a motion effect.

The optical structure and the comparison patterns can be configured in particular positioned between them so as to create a magnifying Moiré effect or an animation effect caused by the observation of at least two different images during a change of viewing angle. The animation effect can be obtained with a comparison pattern formed by interleaving said at least two different images.

At least two comparison patterns, possibly consisting of several elementary patterns, may be located at different distances from the optical structure, and in particular the focal point of a lens of the optical structure, so that the images of these patterns of Comparison through the optical structure each appear in different planes, especially in planes at different depths.

For example, it is possible to form, especially by printing, on a comparison pattern, possibly consisting of several elementary comparison patterns, or on the face of the substrate opposite to the face bearing the comparison pattern, a secondary comparison pattern, notably of size. different. In the case of a secondary comparison pattern formed on the face of the substrate opposite to the face bearing the comparison pattern, the secondary comparison pattern may or may not be superimposed on the comparison pattern. As a result, at least one of the images of the comparison pattern and the image of the secondary comparison pattern can be viewed in different planes.

An additional pattern may be formed, in particular by printing, on the face of the substrate opposite to the face carrying the comparison pattern or on several comparison patterns or on a comparison pattern consisting of several elementary comparison patterns. The dimensions of the additional pattern can be chosen so that only the comparison patterns or the elementary comparison patterns are affected by the optical structure, the additional pattern constituting a background on which the image is observed through the optical structure of the patterns. comparison or basic reasons for comparison.

At least one of the images of the comparison pattern may possibly be observable only in a predefined light, for example ultraviolet and / or infrared.

The reference and comparison patterns, and / or the images observed of these patterns, may be of the same color or not, of the same orientation or not.

The reference and comparison patterns may be of different sizes and / or colors, and the observed images of these patterns of the same size and / or color, or vice versa. The reference pattern and / or the comparison pattern may have a surface area of between 10 and 60 mm ² , for example of the order of 40 mm ² .

The reference and comparison patterns, and / or the observed images of these patterns, may be of shapes and / or dimensions, in particular size, similar, or even identical.

The dimensions of the comparison and reference patterns may be identical or of the same order of magnitude. Alternatively, the scale between the reference and comparison patterns may be variable. For example, the comparison pattern, respectively the reference pattern, may have a size between 0.5 and 3 times the size of the reference pattern, respectively of the comparison pattern.

When the reference and comparison patterns are made with different sizes, the optical structure can be made to change the apparent size of the comparison pattern so that the apparent size of the comparison pattern as seen through the structure approximately equal to that of the reference pattern. The apparent size of the comparison pattern observed through the optical structure may still be between 0.5 and 3 times the size of the reference pattern.

By way of example, a reference pattern of 5 mm ² and a comparison pattern of 1.25 mm ² with a targeted magnification of 3 make it possible to obtain the same aspect observed despite a surface comparison pattern equal to 0, 25 times that of the reference pattern.

Similarly, if a magnification of 150 is desired for the comparison pattern with the same reference pattern of 5 mm ² , then the comparison pattern must have an area of 0.025 mm ² , or 0.005 times the size of the reference pattern. .

The largest dimension of the reference pattern may for example be between 1 and 3 mm.

The largest dimension of the comparison pattern is preferably smaller than the largest dimension of the reference pattern. The largest dimension of the comparison pattern is for example between 0.1 and 0.3 mm.

The largest dimension of at least one of the observed images of the comparison pattern may be substantially equal to the largest dimension of the reference pattern, for example between 1 and 3 mm. The security element may comprise a plurality of reference patterns and / or comparison patterns carried on the same or different faces of the substrate, for example more than 2, more preferably more than 3, more preferably more than 4.

The security element, in particular the substrate of the security element, may comprise an alternation of reference patterns and comparison patterns in at least one direction of a plane of the security element, making it possible, for example, to observe an alternation of still images and moving images.

The number of reference patterns may or may not be the same as the number of comparison patterns.

The comparison pattern and / or the reference pattern may be formed on the substrate by metallization and / or demetallization, for example aluminum. Metallizations and / or demetallizations are more difficult, if not impossible, to reproduce by printing because of their fineness, which makes it possible to avoid counterfeiting by printing.

The comparison pattern and / or the reference pattern may be formed positive or negative on the substrate of the security element. In particular, all the comparison patterns and all the reference patterns can be formed in positive, or alternatively all in negative.

The comparison pattern and / or the reference pattern can be formed by printing. The reference pattern and / or the comparison pattern can be carried on the substrate of the security element for example by a printing process of the offset type, intaglio, laser, inkjet, micro-lithography, gravure or by screen printing.

The reference pattern and / or the comparison pattern can be printed with colored or non-colored inks, visible to the naked eye, under ultraviolet (UV) and / or infrared (IR), opaque, fluorescent, phosphorescent, thermochromic, photochromic, translucent and / or transparent, among others.

The reference patterns may in particular be formed in positive by metallization of the substrate or negative by demetallization of the substrate, and the comparison patterns may for example be impressions made on the substrate.

The reference and / or comparison patterns can be formed by offset printing, laser, inkjet or intaglio printing, flexography, lithography (and micro-lithography), gravure printing and screen printing. The patterns include, for example, micromotives made by microlithography or by intaglio printing.

The optical structure can focus the light at image points, the image given by the optical structure resulting from the focusing at the image points of at least one light source illuminating the optical structure. In this case, the substrate may bear only the reference pattern and the optical structure, being in particular devoid of comparison pattern.

The optical structure, for example consisting of several elementary optical structures, may have different sizes or shapes, in order to produce image points of a light source at different distances, for example.

The light source illuminating the optical structure for the production of image points is for example the sun or an electric lamp, especially a source whose incident rays are parallel or substantially parallel.

The images given by the optical structure and a possible reference pattern may be observable in reflection and / or in transmission. In the case where at least one of the images given by the optical structure results from the observation of image points of a light source, said image can be observed in reflection.

The substrate may or may not carry the optical structure and a reference pattern on the same face.

The substrate may or may not carry a comparison pattern on the face opposite to that carrying the optical structure.

Preferably, the substrate bears on one of its faces a reference pattern and a comparison pattern, and the optical structure on its opposite face.

The substrate may be at least partially transparent or translucent. The substrate may for example be or comprise a film of a transparent or non-transparent thermoplastic material, for example polyester or PET.

The security element may or may not extend from one edge to the other of an object incorporating it, including a security document.

The security element may be a security thread, a security film or a patch. Preferably, the security element is a security thread. The security element may have a width for example greater than or equal to 4 mm, better 5 mm, better still 6 mm, for example between 6 and 8 mm, better between 6 and 10 mm.

The security element in the form of security film or patch may for example be incorporated in a security sheet having a reduced thickness area for receiving the security element.

Advantageously, the width of the security element in the form of security thread may allow the security element to comprise a reference pattern, an optical structure and possibly a comparison pattern of sufficient size to allow easy observation. to the naked eye, while also allowing to integrate at least one other type of security element on the security wire, as described below, including metallizations and / or demetallizations associated or not with magnetic elements.

In the case of carrying out the reference pattern by printing, transparent conductive inks can be used on the reference pattern area and / or the reference patterns can be printed with a magnetic and / or conductive ink, for example black in color, for example based on carbon black.

In the case of a security element in the form of a security thread, the optical structure may extend only partially over the width of the security thread so that the security thread substrate has at least one non-edging area. covered by the optical structure. Such a security thread may for example be introduced into a window of an object.

The border zone may be metallized or not. The border zone may be uncovered by a comparison pattern and / or a reference pattern and / or an optical structure. The border zone may be continuous or discontinuous.

The border zone may extend from one edge to the other of the security element, in particular according to the length of the security element.

The edge zone, in particular where it has no optical structure, may be covered, at least partially, by an adhesive, in particular a heat-sealable varnish. An edge zone covered with such an adhesive can enhance the cohesion between the security element and an object in which it is incorporated. The security element is for example incorporated in a window formed in a base fibrous of the object with at least partial overlap between the edges of the window and the adhesive of the border zone. Thanks to this covering, the fibers of the base of the object can be secured to the security element. It is thus possible to reinforce the cohesion between the security element and the object, in particular when the security element is arranged in a window, which can make the extraction of the security element of the object without damage to the security element. security more difficult. This can reduce the risk that a security element disposed in a window of a base of an object is removed from this object and then reintroduced into another object.

The border zone can be covered with adhesive along its entire length along the security thread, contrary to what is described in the application US 2008/0182084.

The border zone may or may not include at least one magnetic or conductive element, especially in the form of a patch. In this way, it is possible to confer on the security element electrical properties and magnetic properties.

The width of the border zone may for example be between 0.5 and 2 mm, for example 1.5 mm.

The width of the space between two border zones, or between an edge zone and an edge of the security element, is for example between 2 and 9 mm, for example between 3 and 6 mm.

The security element may advantageously comprise at least two edge areas near each of its edges, including its edges along its length.

The security element may or may not be incorporated in window (s) in an object, in particular a security document. When the security element is incorporated in window (s) in a security document, the window can advantageously make it possible to observe at least partially the optical structure, in particular to allow simultaneous observation within the window of at least part of the image given by the optical structure and a reference pattern.

The security element can still be fully incorporated, especially in bulk, or partially in an object, in particular in a security document. The security element incorporated in an object can be visible totally or partially on only one of its faces or on its two faces.

The observation of the security element can be done or not by means of a mask having an opening, the mask being placed on the security element of such that the aperture makes it possible to simultaneously observe at least a part of a reference pattern and at least a part of the optical structure, for example close to each other, in particular juxtaposed one to the other. 'other.

Object

The invention is also concerned with an object, in particular a security document, incorporating a security element as defined above. Such a security document may comprise a paper-based fibrous base and / or a synthetic base and the security element may have at least one visually accessible portion, for example extending in window (s) in this fibrous base.

The security element may be intended to be viewed from a single side of the document, the mirror or mirrors or other elementary optical structures being formed on the side of the substrate opposite to the face facing the observer. As a variant, the security element may comprise, over a portion of its length, mirrors turned towards one of the faces of the substrate, and over another portion of its length, mirrors turned towards the opposite face of the substrate, in order to allow the observation of one or more comparison patterns by reflection of their image on the reflecting surface of the corresponding mirror or mirrors, independently of the observation face of the security element. Other combinations of optical structures are possible, including the combination of concave and convex spherical mirrors.

The metallization thickness defining the reflecting surface of the mirror may be sufficient to render the mirror opaque. Alternatively, the thickness is thin enough to give the mirror a semi-reflective character. Where appropriate, the metal layer may comprise partial demetallizations, for example obtained by performing the metallization through a mask.

The reflective effect can still be obtained by applying a high refractive index layer. In this case, the reflective structure may not include metallization. High refractive index layers are formed of high refractive index (HRE) compounds such as, for example, zinc sulfide. These compounds are used in particular to make holograms.

According to another of its aspects, the invention also relates to an object, in particular a security document, comprising a fibrous paper base and at least one a security thread incorporated in the fibrous base, the security thread comprising, before said incorporation into the object, a substrate bearing on at least one of its faces at least:

an adhesive, in particular a heat-sealable varnish, at least partially covering said face of the substrate without completely covering the optical structure

the security thread having, when incorporated in the object, at least one visually accessible portion extending into window (s) in this fibrous base and the border regions of the substrate being devoid of optical structure and covered by the adhesive .

Other security features

The security document, or the security element that it comprises, may comprise one or more additional security elements as defined below.

Among the additional security features, some are detectable to the eye, daylight or artificial light, without the use of a particular device.

These security elements comprise for example colored fibers or boards, fully or partially printed or metallized wires. These security elements are called first level.

Other types of additional security elements are detectable only with a relatively simple apparatus, such as a lamp emitting in the ultraviolet (UV) or infrared (IR). These security elements comprise, for example, fibers, boards, strips, wires or particles. These security elements may be visible to the naked eye or not, being for example luminescent under a lighting of a Wood lamp emitting in a wavelength of 365 nm. These security elements are said to be second level.

Other types of additional security elements require for their detection a more sophisticated detection device. These security elements are for example capable of generating a specific signal when they are subjected, simultaneously or not, to one or more external excitation sources. The automatic detection of the signal makes it possible to authenticate, if necessary, the document. These security elements comprise, for example, tracers in the form of active, particle or fiber, capable of generating a specific signal when these tracers are subjected to optronic, electrical, magnetic or electromagnetic excitation. These security elements are said to be third level.

The additional security element (s) present in the security document, or the security element thereof, may have first, second or third level security features.

The additional security element (s) may for example be present on one or more border zones of the security element. For example, the security element may comprise in a central zone of the substrate, a reference pattern, an optical structure and possibly a comparison pattern, and in one or more border zones, one or more additional security elements such as described above.

Manufacturing process

The invention further relates, in another of its aspects, to a method of manufacturing a security element comprising a substrate, in which:

at least one of the faces of the substrate is made of at least one optical structure only partially covering said substrate face, for example an array of elementary optical structures superimposed, where appropriate, on at least one comparison pattern present on the substrate , and optionally at least one reference pattern is made on said face of the substrate,

an adhesive, in particular a heat-sealable varnish, is applied to the substrate, the adhesive at least partially covering said face of the substrate without completely covering the optical structure.

The formation of the optical structure can be done for example by printing in flexography, inkjet, offset or screen printing, for example an ink dot of a transparent polymer crosslinkable under UV, or by hot embossing a thermoplastic support with an engraved metal matrix in the form of a lens, among other possibilities.

The formation of the optical structure may or may not be on the same side of a substrate comprising a comparison pattern, with or without marking of the basic optical structure with respect to the comparison pattern. In case of registration, the comparison pattern is for example centered on the optical axis of the optical structure. It is possible to produce a lenticular network comprising a plurality of identical lenses, which are metallized in order to form a network of non-planar mirrors.

Description of figures

The invention may be better understood on reading the following detailed description, nonlimiting examples of implementation thereof, and on examining the appended drawing, in which:

FIG. 1 represents in cross-section, schematically and partially, an exemplary embodiment of a security element according to the invention, comprising a non-reflecting optical structure,

FIGS. 2 and 3 illustrate, in front view, the observation of security elements such as that of FIG. 1,

FIG. 4 is a schematic and partial cross-sectional view of another embodiment of a security element according to the invention, comprising a reflective optical structure;

FIGS. 4A to 4C illustrate steps in the realization of the reflective optical structure of FIG. 4,

FIGS. 5 to 7 show examples of objects comprising a security element according to the invention,

FIGS. 8 to 9 illustrate alternative embodiments of reflective optical structures,

FIG. 10 is a view similar to FIG. 9 of an alternative embodiment, FIG. 11 is a top view along X of FIG. 10, FIG. 12 illustrates a mesh according to which certain reflecting structures can be arranged.

FIG. 13 represents an exemplary reflective structure, FIG. 14 represents an example of a pattern that can be realized with the reflective structures of FIG. 13,

FIG. 15 represents another example of a reflecting structure, FIG. 16 represents the reflecting structure of FIG. 15, according to XV,

FIG. 17 represents another example of a security element according to the invention, FIG. 18 is a view according to XVII-XVII of FIG. 17, FIGS. 19 and 20 respectively show, in front view, the front and the back of another example of a security element according to the invention,

FIGS. 21 and 22 show, respectively in section and in front view, another embodiment of a security element according to the invention, and

FIGS. 23 to 25 show, in section, other embodiments of security elements according to the invention,

Figures 26 and 27 show other embodiments of security elements according to the invention and - Figures 28 to 33 represent objects incorporating a security element according to implementation examples of the invention.

The security element 1 represented in FIG. 1 comprises a substrate 6 whose front face 7 is covered by a plurality of reference patterns 3 and several comparison patterns 5, formed for example by micro-printing, in particular by a micro-printing technique. lithography or soft printing. The comparison patterns 5 and the reference patterns 3 may for example be printed with a white or colored ink. The comparison patterns 5 and the reference patterns 3 may be as described above, in particular of the same size or not, of the same color or not, or even of the same orientation or not.

The substrate 6 is for example a transparent film of synthetic material, for example a thermoplastic material, in particular polyester.

The substrate 6 bears on its back side 7 ', a non-reflecting optical structure 4, consisting of several elementary optical substructures. In the example of FIG. 1, these optical substructures are disjoint and are formed by elementary optical structures such as lenses. These elementary optical structures may be disjoint or not and / or identical or not.

The security element 1 may be covered on one or both of its outer faces with an adhesive 14, in particular a heat-sealable varnish. As illustrated in FIG. 1, the adhesive 14 may, for example, completely cover the front face 7 of the substrate 6 carrying the reference patterns 3 and the comparison patterns 5, and cover the back face 7 'of the substrate 6 only between the optical substructures of the optical structure 4, never covering optical substructures so as not to deteriorate their optical properties.

The adhesive can be transparent at least on the observation side for example. In particular, the adhesive may be a heat-activatable adhesive, such as a heat-sealable coating or a heat-sealable varnish. Such adhesives are particularly advantageous when they are used in processes operating at high temperatures, especially with drying operations commonly used in the field of paper mills. Examples of adhesives, especially heat-sealable varnishes, include an ultraviolet (UV) crosslinkable agent, an adhesive to be irradiated, a pressure-sensitive adhesive (PSA), a varnish with a solvent base, of the polyester type, for example , an adhesive in aqueous phase, etc. As an aqueous phase adhesive, there may be mentioned those known under the following brands: Mowilith DC (aqueous dispersion of vinyl acetate homopolymer with particles of size ranging from 0.3 μιη at 2 μιη and a glass transition temperature Tg of about 38 ° C., and a dry solids content of between 55 and 57%) and Vinamul 3265 from CELANESE; DH9004, DH9017, DH9044 and DL5001 from the company COLLANO; Primal NW1 845, Primal LC40, Primal P308M and Primal EP6000 from ROHM &HAAS; the 006SDW078-2 from BASF.

The adhesive 14 may make it possible to improve the adhesion of the security element 1 within an object in which it is intended to be inserted, in particular a paper mass.

The reference patterns 3 correspond for example substantially to the images of the comparison patterns 5 by the optical structure 4. In this way, the authentication and / or the identification of the security element 1 can be done by observation on the back side. 7 'of the substrate 6 carrying the optical structure 4.

Figures 2 and 3 illustrate, in front view, examples of observation of a security element 1 according to the invention, obtained for example from the security element 1 of Figure 1.

FIG. 2 represents the observation of a security element 1 in which the comparison patterns 5 and the reference patterns 3 have been made in a positive state, for example by metallization. FIG. 3 illustrates an example of observation of a security element 1 according to the invention, in which the comparison units 5 and the reference units 3 have been made in negative, for example by demetallization.

The observation of the images obtained from the comparison patterns 5 and the reference patterns 3 may make it possible to authenticate and / or identify the security element 1 by virtue of the visual similarity observed.

FIG. 4 shows another example of a security element 1 according to the invention, comprising a reflective optical structure 4.

The security element 1 comprises a substrate 6 carrying, for example on its front face 7, reference patterns 3, and on its reverse face 7 'comparison patterns 5, the optical structure 4 consisting of several optical sub-structures superimposed for reasons of comparison 5.

At least one optical substructure, and in particular the reflective optical structure 4 may for example be in the form of an array of elementary optical structures which are in the example considered lenses 9. A single lens 9 is shown in FIGS. 4B and 4C and these lenses 9 having a face 10, the opposite side of the substrate 6, which is non-planar, for example substantially shaped spherical cap, as illustrated.

This face 10 may be covered by a reflective coating 11, so as to form a non-planar mirror 12 constituting a reflective optical structure 4.

FIGS. 4A to 4C illustrate an exemplary embodiment of a reflective optical structure 4 of a security element 1 according to FIG. 4, for example.

It is possible to start by coating the substrate 6 with a comparison pattern 5. Next, the lenticular network can be formed by covering the comparison pattern 5, as illustrated in FIG. 4B. The formation of the lenticular network can be carried out in a way that is marked or not with respect to the comparison pattern 5.

The lenses 9 can for example be formed by a printing technique, for example flexography, inkjet, offset or screen printing, of ink dots of a transparent polymer ink which can be crosslinkable under UV.

The lenses 9 can also be made by gravure printing.

The formation of the lenses 9 can also be done by hot embossing the substrate 6 with a metal matrix engraved in the form of a lenticular array. Next, the non-planar surface of the lenticular array is metallized to form the mirrors as shown in FIG. 4C. The metal is for example aluminum.

FIGS. 4B and 4C show that a comparison pattern 5 can be located in the concavity of the corresponding mirror.

In the example considered, the mirror 12 has a concave reflecting face and the distance d between the face 7 of the substrate 6 and the bottom 15 (also called "top") of the concavity of the mirror 12 is for example 15 μιη, for a diameter D at the interface 13 with the substrate 6 of about 60 μιη.

Thus, the radius of curvature of the mirror 12 may be about 37.5 μιη and the focal length of the mirror is then 18.8 μιη. As a result, the mirror 12 provides an enlarged image of the comparison pattern 5 to the observer O.

The comparison pattern 5 is for example an impression of 20 μιη wide. The substrate 6 is for example 23 μιη thick.

In the example of FIG. 4, it is possible to obtain a right virtual image larger than the comparison pattern 5, the latter being located between the focal point and the top 15 of the concave mirror.

In another variant embodiment, the mirrors 12 are made with a convex reflecting surface towards the comparison patterns, as illustrated in FIG. 8, which produces a smaller image of the comparison patterns.

If necessary, another optical device, for example a magnifying lens, for example of the Fresnel lens type, may be associated with a reflecting mirror so as to enlarge the image produced by the mirror again.

In another variant embodiment illustrated in FIG. 9, the image or images seen by the observer do not come from a printed comparison pattern but consist of all the light spots created at the focal length of each mirror. The mirrors 12 may, as illustrated, be of different sizes to create light points, for example of different sizes or located at different distances from the observer's eye.

In this case, the comparison is made between the reference patterns 3 and the images formed by all the light spots created by the mirrors. FIGS. 10 to 16 show variant embodiments in which at least one of the images seen by the observer is due to the way in which the light is reflected by a plurality of reflective structures, of at least two types different.

In FIG. 10, it can be seen that the transparent substrate 6 may comprise on one face a plurality of reflective structures 4a and 4b, of different respective shapes or dimensions, covered by a layer 1 1, making it possible to create a reflecting surface, for example a layer of metal. The reflective structures 4a are, for example, sphere portions as illustrated in FIGS. 15 and 16, of height h, for example between 10 and 20 μιη, for example of the order of 15 μιη, and of diameter Δ, for example between 20 and 40 μιη, for example of the order of 30 μιη.

The reflective structures 4b are, for example, mirrors of pyramidal or truncated pyramid shape, for example having a square base of side W _x or W _y for example between 20 and 40 μιη, for example of the order of 30μιη, the most large dimension W _x or W _y being for example equal to the diameter Δ at the reflective base of the reflective structures 4a.

The reflective structures 4b are for example arranged as the meshs of a network, as shown in FIG. 12, of pitch W for example equal to Δ, for example of the order of 30μιη. The reflective structures 4b can be arranged in patterns, as shown in Figures 14 and 11. The reflective structures 4a and 4b can be formed in various ways, for example by printing relief and metallization of these reliefs.

The security element 1 may be in the form of a security thread, for example intended to be incorporated into windows in a paper 40, as illustrated in FIG.

In this case, the security element 1 extends for example between two opposite edges of the paper. The security element can come to the surface of the paper by its outer face located on the opposite side to the optical structure, at a window 30.

In a variant, as illustrated in FIG. 6, the security element 1 is applied in the form of a patch.

The security element 1 can still be integrated into a package, as shown in FIG. 7, or to a label. FIGS. 17 and 18 show another example of a security element 1 according to the invention, in the form of a security thread.

The security element 1 comprises a substrate 6 on the back 7 'of which there are reference patterns 3, made for example positive by demetallization.

The security element 1 also comprises comparison patterns 5, formed for example by printing on the substrate 6, of suitable size as they are seen through the optical structure, and arranged alternately in the longitudinal direction with the reference patterns. three.

The security element 1 also comprises an optical structure 4 consisting of several optical substructures each comprising elementary optical structures and covering the comparison patterns 5.

The optical substructures are for example in the form of parallelograms whose long side is not perpendicular to the length of the security element 1, as shown in FIG. 17.

The security element 1 can be incorporated or not into windows (s) in a security document.

When embedding in window (s), the window F may for example be made in such a way as to be able to observe at least part of a comparison pattern and part of a reference pattern, as can be seen on Figure 17.

The security element 1 further comprises at its edges two zones of metallized borders 20a and 20b, continuous, and comprising magnetic elements 21. In this way, the security element may have electrical conductivity properties and properties magnetic.

The width / zones metallized borders 20a and 20b is for example between 1 and 2mm, for example equal to 1, 5 mm.

The width L of the central zone of the security element carrying the reference patterns 3, the comparison patterns 5 and the optical structure 4 is for example between 3 and 4 mm.

The security element 1 may comprise a substrate 6 of PET, of a thickness for example equal to 23 mm. The optical structure 4 may comprise a network of elementary optical structures being for example lenses having a thickness of 6μιη and a diameter equal to 20μιη.

The security element 1 can also be covered with an adhesive 14, in particular a heat-sealable varnish, for example on the entire back face 7 'of the substrate 6 opposite to the optical structure 4, as can be seen in FIG. FIG. 18, and only outside the optical structure 4 on the front face 7 of the substrate 6.

The thickness of the adhesive is for example between 3 and 4 μιη. The magnetic elements 21 may be printed on the metallized zones 20a and 20b, or alternatively on the surface of the substrate 6 and then covered by the metallized zones 20a and 20b.

Figures 19 and 20 respectively show, in front view, the front and back of another example of security element 1 according to the invention.

In this example, the security element 1 comprises, on its front, an optical structure 4 constituted by a plurality of optical sub-structures, in particular of rectangular shape, the long side of which is parallel to the long side of the security element 1. The substrate 6 may carry, between the optical substructures, one or more reference patterns (not shown).

The optical structure 4 does not extend from one edge to the other of the security element 1 according to its width. In this way, the security element 1 has two border zones 20a and 20b.

The border zones 20a and 20b are for example covered with an adhesive 14. The adhesive 14 can also be applied between the optical substructures, as represented in FIG. 19.

Border areas 20a and 20b may or may not include one or more security elements as described above.

On the back side, as shown in FIG. 20, the security element 1 can be completely covered with an adhesive 14.

The substrate 6 of the security element 1 may or may not comprise one or more comparison units (not shown) so that the optical structure is superimposed on the (x) pattern (s) of comparison. The comparison pattern or patterns may be carried by the front and / or back face of the substrate 6 of the security element 1. The width / border areas 20a and 20b is for example between 1 and 2 mm, for example equal to 1, 5 mm.

The width L of the central zone of the security element 1 carrying the optical structure 4 is for example between 3 and 4 mm.

Figures 26 and 27 show another example of a security element in which the border areas 20a and 20b are covered with adhesive.

In the example of Figure 26, adhesive bridges extend above the face 7 of the substrate, for example at the locations of the face 7 where the reference patterns 3 are arranged. These reference patterns 3 can then be observable through the adhesive bridges.

In the example of FIG. 27, the face 7 of the substrate 6 is covered with adhesive 14 only at the level of the border zones 20a and 20b.

As can be seen in Figs. 26 and 27, the adhesive 14 may be disposed on the border areas along the entire length of the wire.

Figures 28 to 33 show in section and schematically an object 100 in which a security element 1 according to Figure 26 or 27 is incorporated.

In the examples of FIGS. 29, 31 and 33, the security element 1 is incorporated in a window formed in a fibrous base 200 of the object 100. The edges of this window form a covering zone Z between the fibrous base 200 and the adhesive 14. This covering area may extend all along the window and then allow the fibers of the fibrous base 200 to be bonded to the security element over the entire length of the window.

FIGS. 21 and 22, respectively in section and in front view, show another example of a security element 1 according to the invention.

In this example, the security element 1 comprises a substrate 6 on one side

7 'of which is an optical structure 4 completely covering said face 7'. The optical structure 4 is formed by non-disjoint optical sub-structures.

The face 7, opposite to the face 7 'carrying the optical structure 4, carries reference patterns 3 and comparison patterns 5.

The optical structure 4 is partially covered by an inactivation varnish

14 'which is superimposed on the reference patterns 3. The mactivation varnish 14 'is advantageously a varnish canceling the optical effect (s) of the optical structure 4. The observation of the reference patterns 3 through the optical structure 4 covered with the mactivation varnish 14' corresponds to the direct observation that would be made of the reference patterns 3 without the presence of the optical structure 4. In this way, the optical structure 4 retains its optical effects only in the areas not covered by the varnish mactivation 14 ', including areas superimposed on the comparison grounds 5.

The mactivation varnish 14 'may be chosen so as to have a refractive index which makes it possible to cancel the optical effects obtained by the optical structure 4. The refractive index of the mactivation varnish 14' can for example be the same that of the optical structure, in particular of the zone of the optical structure 4 on which the mactivation varnish 14 'is applied.

The outer surface S _e of the glazing varnish 14 'is advantageously flat.

In FIG. 22, the image of the comparison pattern 5 represented for example corresponds to a magnification of the comparison pattern 5 carried by the substrate 6 due to the observation through the optical structure 4. The reference pattern 3 is 1 to 1 and can for example have the dimensions of the reference pattern 3 after magnification. Indeed, the observation through the optical structure 4 of the reference pattern 3 does not produce any effect, in particular no magnification, of this pattern due to the cancellation of the optical effects by the mactivation varnish 14 ' .

In this example also, the face 7 of the substrate 6 is completely covered with an adhesive 14, in particular a heat-sealable varnish. The adhesive 14 is also applied to the mactivation varnish 14 'covering the optical structure 4 carried by the face 7' of the substrate 6.

The presence of the adhesive 14 on the face 7 'of the substrate 6 covering only the areas of the optical structure 4 covered with the mactivation varnish 14' may make it possible not to deteriorate the optical observation properties of the optical structure 4 in areas not covered by the mactivation varnish 14 ', in particular the zones of the optical structure 4 superimposed on the comparison units 5.

Alternatively, the adhesive 14 could be a varnish mactivation and therefore, the varnish activation 14 'could be omitted, the optical structure 4 is not covered partially as adhesive 14 having a character of inactivation of the optical effects of the optical structure 4.

FIGS. 23 to 25 schematically and partially show other exemplary embodiments of security elements 1 according to the invention.

In the example of FIG. 23, the substrate 6 carries on its face 7 a comparison pattern 5, and on its face 7 'a secondary comparison pattern 5'. As previously described, the respective images of the comparison patterns 5 and 5 'thus appear for the observer's eye at different distances thus creating an effect of volume and depth.

In the example of Figure 24, the substrate 6 carries on one of its faces 7 a comparison pattern 5 and on the other of its faces 7 'an additional pattern 5'.

The comparison pattern 5 and the additional pattern 5 '' thus produced can make it possible to observe at least one of the images of the comparison pattern through the optical structure 4 and the additional pattern 5 "unaffected by the optical structure in The additional pattern 5 "is not affected by the optical structure, for example because of its distance from the optical structure and / or because of its large size relative to the elementary optical structure or not. In particular the additional pattern 5 ", although placed in a plane farther from the observer than the comparison pattern 5, may appear in the foreground.

In the example of FIG. 25, the substrate 6 carries on its face 7 a comparison pattern 5 constituted by a plurality of elementary comparison patterns 5 a.

An additional pattern 5 "is formed on the comparison pattern 5 and has larger dimensions than the elementary comparison patterns 5a so that only the observation of the elementary comparison patterns 5a is affected by the optical structure 4. The additional pattern 5 "may appear as a background on which the image is observed through the optical structure 4 of the elementary comparison patterns 5a. As above, at least one of the images through the optical structure 4 of the elementary comparison patterns 5a and the additional pattern 5 "appear in different planes.

The phrase "with one" should be understood as synonymous with

"With at least one" unless otherwise specified.

Claims

1. Security element (1) comprising a substrate (6) bearing on at least one of its faces at least:

an optical structure (4) producing at least one image of at least one pattern (5) and / or producing image points of a light source illuminating the optical structure,

an adhesive (14), in particular a heat-sealable varnish, at least partially covering said face of the substrate (6) without completely covering the optical structure (4),

the security element (1) being a security thread, the optical structure (4) extending only partially over the width of the security thread (1) so that the substrate (6) of the security thread (1) ) has at least one edge region (20a, 20b) not covered by the optical structure (4).

2. Safety element according to claim 1, being a safety thread having a width greater than or equal to 4 mm, more preferably 5 mm, more preferably 6 mm, in particular between 6 and 8 mm, more preferably between 6 and 10 mm.

3. Security element according to one of the preceding claims, the optical structure (4) only partially covering said face of the substrate (6).

4. Security element according to claim 3, the adhesive (14) completely covering the area or areas of said face of the substrate (6) not covered (s) by the optical structure (4).

5. Security element according to one of the preceding claims, the optical structure (4) not extending from one edge to the other of the substrate (6) along the length and / or the width of the substrate.

6. Security element according to any one of the preceding claims, the optical structure (4) being discontinuous, consisting of a set of disjoint optical substructures, the adhesive (14) covering for example the zone or zones of said face of the substrate (6) not covered by the optical substructures.

7. Security element according to any one of the preceding claims, said at least one edge region (20a, 20b) being covered by the adhesive (14).

8. Security element according to any one of claims 1 to 7, said at least one edge region (20a, 20b) having at least one magnetic element (21).

9. Security element according to any one of the preceding claims, said at least one edge region (20a, 20b) having a width of between 0.5 and 2 mm.

10. Security element according to any one of claims 1 to 10, comprising two edge regions (20a, 20b) spaced apart by a distance of between 2 and 9 mm, preferably between 3 and 6 mm.

11. Security element according to any one of the preceding claims, the optical structure (4) comprising a lenticular array.

12. Security element according to any one of the preceding claims, the optical structure (4) being reflective.

13. Security element according to any one of claims 1 to 12, the optical structure having a non-planar outer surface.

14. Security element according to any one of the preceding claims, the optical structure (4) being partially covered with at least one inactivation varnish (14 ') canceling the optical effect (s) obtained by the optical structure (4). .

15. Security element according to claim 14, the inactivation varnish (14 ') being superimposed on one or more reference patterns (3) carried by the substrate (6), in particular by the face (7) of the substrate (6). opposite the face (7 ') carrying the optical structure (4) ·

Object, in particular security document, incorporating a security element (1) according to any one of the preceding claims.

17. Object according to the preceding claim, the security element (1) being incorporated into the window (s) in the object, in particular so as to be able to at least partially observe the optical structure (4) in at least one window.

18. Object according to one of claims 16 and 17, the security element (1) does not extend from one edge to the other of the object.