FR3020987A1 - METHOD FOR MANUFACTURING A SECURITY ELEMENT - Google Patents

Abstract

The present invention relates to a method of manufacturing a security element (3) of elongated shape in a longitudinal direction, for secure document, having in the longitudinal direction a succession of optically active zones, this method comprising the steps of: a . providing on a substrate (50) a succession of generally parallel optically active strips (31, 32) so as to form a base film (40), b. cutting the security element (3) into the base film in a direction (SM) generally transverse to the strips.

Description

The present invention relates to security elements and valuable or security documents incorporating such elements. The invention relates more particularly but not exclusively to a security thread and its method of manufacture.

Security threads are band security elements that are often used in banknotes to help make counterfeits more difficult and to authenticate them. Many sons aim to offer a security easy to recognize for the man of the street and difficult to reproduce.

Such wires are for example described in documents WO2013 / 034476, EP659936, EP0400902, WO2004 / 040062, WO2007 / 036683 and WO2005 / 069231. W02013 / 034476 discloses in particular two parallel strips present on the same security thread, which change appearance with the angle of observations. EP 1 819 525 discloses a security element comprising platelet-shaped pigments which can be oriented under the effect of a magnetic field so as to make it possible to observe, for a direction of observation substantially parallel to the orientation of the pigments , an underlying impression. In the application WO 2012/176169 A1, the security element has two optically active zones whose magnetic pigments are oriented differently, so that one can observe an appearance and disappearance of the underlying patterns when the direction of observation changes. The security element may be in the form of a wire, cut from a base film having a plurality of parallel strips. The cutting of the son is carried out parallel to the strips, mid width thereof. A disadvantage of such a manufacturing method is to require a modification of the tape making equipment if the width of the wire is to be changed. However, depending on the applications or the size of the bank notes, the width of the wire can be varied. In addition, in the case of narrow wires, the realization of customization prints of the wire can be difficult. US 2013/0087060 discloses a device for subjecting a substrate carrying a magneticin pigment ink to a magnetic field of orientation of the pigment particles. The invention aims to further improve the security elements, especially to facilitate their manufacture in different widths, and it achieves, according to a first aspect, through a method of manufacturing an elongated security element according to a longitudinal direction, for secure document, having in the longitudinal direction a succession of optically active zones, this method comprising the steps of: a. producing on a substrate a succession of optically active bands, preferably optically variable, generally parallel, so as to form a base film, b. cutting the security element in the base film in a direction generally transverse to the strips. Cutting the security element Clans in a direction generally transverse to the strips makes it possible to produce the security element with the desired width; the same equipment can be used to make the tapes, regardless of the subsequent width of the security element. The manufacture of the security element is simplified with respect to the method described in WO 2012/176169 A1. In addition, this solution makes it possible, if desired, to make security elements comprising more optically active zones. wide, which advantageously allows to accentuate the optical effects. In addition, having wider security threads can facilitate their personalization, including printing. The security element may be integrated into a fibrous substrate of a document, or serve as a transfer element for depositing optically active structures on a document, this transfer being effected under heat and pressure, for example, by virtue of the strips are then removably carried by the substrate of the base film. The optically active bands may comprise first strips alternating with second strips in the cutting direction, the first and second strips having distinct aspects and / or optical effects when observed simultaneously in at least one observation direction . This provides a security element with optical properties that alternate when traversed in the direction of cutting. The appearance may change, depending on how the strips are made, when the viewing direction is rotated about an axis that is parallel to or alternately perpendicular to the strips. The first and second strips can be made in such a way that: a. In a first viewing direction of the base film the first and second strips have different aspects, and b. in a second direction of observation different from the first, the first and second strips have each changed appearance and the first bands have a different appearance than the second bands. The first and second strips can be made in such a way that: a. in a first observation direction of the base film (40) the first 35 bands appear of a first appearance, appearing in particular colored, reflective, transparent, semi-transparent or matte, and the second bands appear of a second aspect, different from the first aspect, appearing in particular colored, reflective, opaque, transparent, semi-transparent or matte, b. in a second direction of observation of the base film, different from the first direction, the first bands appear with the second aspect and the seconds with the first aspect. In particular, the following combinations can be used: - first matt aspect and second reflective aspect or vice versa, - first and second aspects of different colors, - first transparent or semi-transparent appearance and second opaque appearance. A so-called "flip-flop" effect is thus obtained, for example with a luminous "extinction" of substantially half of the surface of the security element when it is observed in reflected light in a certain direction of observation, and inverting the extinction to the other zones of the security element when enough direction of observation is changed. The first and second viewing directions form, for example, an angle of at least 60 ° between them, in particular between 80 and 100 °, preferably a right angle, and are preferably contained in a plane perpendicular to the cutting direction. of the base film. Alternatively, they are included in a plane comprising the cutting direction of the base film and perpendicular to the base film. The optically variable bands preferably comprise magnetically oriented pigments. These pigments are, for example, pigments as described in applications EP 1 819 525 or WO 2012/176169 A1. The strips can be produced by printing using such oriented pigments. The pigments can be deposited by successive passes on the substrate. The latter can be flipped between the passes, which is a simple and effective way to orient the pigment particles differently. The magnetically oriented pigments within the same band may have substantially all the same orientation. The pigments of two adjacent bands on the base film may have different orientations, for example symmetrical orientations on either side of a median plane perpendicular to the substrate and the strips or to the cutting direction. The base film may comprise at least one pattern and / or one luminescent layer 35 which is superimposed at least partially on at least one of the strips, especially when these are produced using oriented pigments, and which becomes then visible when one observes in a direction substantially parallel to the direction of orientation of the pigments. When viewed in a direction substantially perpendicular to the direction of orientation of the pigments, the pattern or the luminescent layer which is superimposed on the pigments is masked and not visible. Each band may also comprise a lenticular network, in particular a network comprising convex lenses, in particular substantially hemispherical lenses. The lenses of the lenticular network make it possible to observe or not, depending on the angle of observation, at least one underlying pattern element. An exemplary lenticular network that may be suitable is described in application WO2012085773. The optically active areas of the security element may be oblique, each zone preferably having an inclination with respect to the longitudinal direction of the security element of between 30 and 90 ° (excluded terminal), better still between 60 and 90 ° (Excluded terminal), the inclination being obtained in particular by making the strips obliquely on the base film and by cutting parallel to an edge of the base film or by making the strips parallel to an edge of the base film and by cutting into a direction oblique to this edge. Each optically active zone may thus have a median axis which makes an angle of between 30 'and 90 °, more preferably 60 and 90 °, with respect to the longitudinal direction of the security element. The width of the optically active strips may be between 1 and 10 mm, more preferably between 2 and 5 mm. The security element that is cut out may have the same width as the bands, or be wider or less wide. The bands may or may not have the same width. Two adjacent bands may be separated by an interval. The substrate can then carry a security element visible at least partially in said gap. The spacing between two optically active strips may still be substantially the same on the base film. The spacing between two optically active strips is for example between 0.1 and 3 mm, better between 0.4 and 1 mm. This spacing may be smaller than the width of the strips, better represent between 1/20 and 1.4 of their width. The presence of a spacing between two bands makes it possible, if desired, to have additional security between them. This security can be present on the substrate on the same side thereof as the strips, or alternatively on the opposite side, and be at least partially visible in reflected light, or in transmitted light if necessary, because of the transparency of the substrate.

In addition to the security provided by the optically active areas resulting from the cutting of the strips of the base film, a security element according to the invention can thus have an additional security of first, second or third level. By "first level security" is meant a security detectable with the naked eye, in daylight or in artificial light, without the use of a particular device. This is for example a security made between the strips or the side opposite the strips, on the base film, for example by printing or metallization / demetallization. Other types of security are detectable only with a relatively simple device, such as a lamp emitting in the ultraviolet (UV) or infrared (IR).

These safeties can be visible to the naked eye or not, being for example luminescent under a lighting of a Wood lamp emitting at a wavelength of 365 minutes. These securities are said of second level. It may be for example a luminescent layer superimposed at least partially on the optically active strips of the base film, and which for example fluoresces under UV.

Other types of security require for their detection a more sophisticated detection device. These securities are for example capable of generating a specific signal when they are subjected, simultaneously or not, to one or more excitation sources. The automatic detection of the signal makes it possible to authenticate, if necessary, the element. These safeties comprise, for example, tracers in the form of active materials, particles or fibers capable of generating a specific signal when these tracers are subjected to optronic, electrical, magnetic or electromagnetic excitation. These securities are said to be third level. This is for example a magnetic strip extending parallel to the strips, and for generating a magnetic coding.

The base film may comprise, in particular between two strips and / or at least partially superimposed on at least one of the strips, on the side of the same substrate side as the strips or on the opposite side: a demetallization, - a magnetic tape , creating a third level security, or - a colored element or effect goniochromatic, metallic or holographic, among other possibilities. The width of the cut security element is for example between 1 and 10, better between 3 and 5 mm. This width can be constant, with parallel and straight edges.

The security element is preferably a security thread, intended to be integrated into a document and to extend from one edge of this document to the opposite edge. The wire can be integrated in window (s). The basic filament substrate is preferably synthetic, made of thermoplastic material, preferably polyethylene terephthalate or polyester. The substrate is preferably transparent, and more preferably colorless. Each strip made on the base film can be continuous or discontinuous in the direction of its length, and be of homogeneous appearance or not along its entire length. Each band may comprise a succession of portions having distinct optical properties. This makes it possible to produce security elements with a larger number of subdivisions and to increase the diversity of the realizable patterns. Each band portion can thus constitute an optically active zone with homogeneous intrinsic properties. In the case of a discontinuous strip or with homogeneous properties in portions only, the distance between two successive optically active portions of the strip, in the length direction thereof, is for example between 0 and 10 mm. . This spacing may be non-zero, that is to say that different portions of the band do not touch and are separated by intervals where we can see through the substrate of the base film for example. The optically active strips being discontinuous and each formed by an alternation of portions having distinct optical properties, with an offset between two successive bands so that said portions are arranged on the film in a checkerboard arrangement, the elements can be cut in at least one of the following ways: the security elements are cut by cutting at mid-length two successive portions of a strip, the security elements are cut by cutting between the successive portions of a strip, or the security elements are cut by cutting between each pair of successive portions of a strip. Two identical base films can be cut in two different ways from the above. In the case of a base film comprising discontinuous strips, it is thus possible to obtain different security elements according to the position of the knife adopted during the cutting of the security elements. In particular, one can arrange the knife: either so that there is knife between each portion of each discontinuous strip, and one then obtains safety elements comprising a succession of portions of strips, all belonging to different bands, when traversed longitudinally, and a single portion of band when traversed transversely, so that there is a knife in the middle of each portion of each discontinuous strip, and one obtains then security elements comprising a succession of pairs of half-portions belonging to as many different bands as there are pairs of half-portions when traversed longitudinally, and two half-portions of the same band when they are traversed transversely, or between each pair of adjacent portions of each band, and safety elements are obtained that have a succession of pairs of portions of bands when they are traversed lo ngitudinally, and two portions of the same band when traversed transversely. Each band portion with homogeneous optical properties is preferably of square or rectangular outline. Alternatively, the outline is more complex, and draws a pattern for example alphanumeric. Preferably, the spacing between two portions of distinct aspects of the same strip is less than the length of a portion, and there is for example a factor of 1/20 to Yi between the spacing between two portions. and the length of these portions.

All the optically active portions of the same band may have substantially the same length. All portions of the different strips of the base film may have substantially the same length. The long w of a band portion is for example between 1 and 5 mm. The security element cut in the base film may have a width substantially corresponding to the length of a strip portion. This width can be even lower or higher. The strip portions preferably comprise magnetically oriented pigments. The magnetically oriented pigments within the same band portion then preferably have substantially all the same orientation. Portions of strips 30 having substantially all the same first orientation are preferably arranged alternately with other portions of strips, having substantially all the same second orientation, for example by a longitudinal offset between the strips, so as to form a checkerboard on the base film. The security element can then be cut to have a width that includes one or more columns of cells of such a checkerboard, or even has only one column of cells.

The different boxes of the checkerboard can be non-joined, so as to allow a cutting of the base film between the boxes. The security element may have a width greater than the length of a strip portion having a homogeneous appearance, so as to have different optical properties when traversing the security element in the direction of its width. For example, the security element has a width sufficient to include two band portions of different aspects, or more. In the case of a checkerboard arrangement, with boxes each of homogeneous appearance, the security element is for example sufficiently wide to accommodate at least two columns or three or more of the checkerboard. Each column can group boxes with different aspects that alternate along the security element. The aspects encountered on a column of boxes may be the same as those encountered on another column present on the same security element. As a variant, the effects encountered on one column are not all found on the other columns. In particular, certain effects encountered on cells located in the direction of the width of the element, among other cells, may be intermediate, so as to obtain, for example, more progressivity in the variation of the effects observed when the direction of observation changes. The invention also relates to a base film for producing a security element by cutting the base film in a machine direction, comprising: a substrate, a succession of optically active strips carried by the substrate, generally parallel, and oriented generally transversely to the machine direction. The optically active strips may be discontinuous and each formed by alternating portions having distinct optical properties, with an offset between two successive bands such that said portions are disposed on the film in a checkerboard arrangement. Portions of a strip may be non-joined. The strips may be spaced from each other in the machine direction. The invention further relates to the security element obtained by the method according to the invention. The invention also relates to an elongated security element, for secure document, having in the longitudinal direction a succession of optically active zones. A security element according to the invention is preferably a security thread. This security thread may have a succession, according to its length, of optically active areas of different aspects, especially whose properties alternate. These optically active zones come from the cutting of respective strips. The optically active areas preferably comprise oriented magnetic pigments: Two optically active areas may have magnetic pigments oriented differently with appearance or disappearance of a reflection during a rotation of the element relative to the observer around the surface. a transverse axis of rotation, in particular perpendicular to the longitudinal axis of the security element. As a variant, two optically active zones may have magnetic pigments oriented differently with the appearance or disappearance of a reflection during a rotation of the element relative to the observer around an axis of rotation parallel to the longitudinal axis of the security element. Preferably, on a 12 to 15 mm segment along the wire, at least two zones of different aspects, and preferably from 3 to 5 zones of different aspects, corresponding to the various aforementioned bands of the base film, are observed. This allows, when the wire is inserted into windows 12 to 15 mm long, a visibility on the wire of at least two optically active areas, which preferably change appearance when the direction of observation changes, as mentioned upper. When the strips of the base film are narrower than the security element which is cut from the base film, each zone corresponding to the portion of strip thus cut has an elongate shape, or possibly square, in a perpendicular direction. over, including a rectangular shape of large side perpendicular to the wire. Thus, with such a wire, new effects are obtained compared to certain threads traversed along their width by bands of homogeneous appearance. Another subject of the invention is a security element comprising an alternation in the longitudinal direction of pairs of adjacent portions, having distinct optical properties, with a checkered arrangement of said portions on the wire, each portion preferably having a rectangular shape. long side parallel to the longitudinal direction of the element or alternatively perpendicular to said direction. The invention also relates to a secure document comprising a security element according to the invention. This security element is preferably a security thread inserted in window (s) in a substrate of the document, which is preferably a papermaking substrate but which can also be a synthetic substrate or a hybrid substrate comprising a paper and a film plastic. The substrate that receives the security element may comprise one or more paper jets.

This substrate may advantageously comprise additional securities, which may be first, second or third level. "Secure document" means a valuable document, for example a means of payment, such as a bank note, a check or a restaurant ticket, a lottery ticket, a ticket or a ticket giving access to a ticket. cultural or sporting event and / or a document for the identification of persons, such as an identity card, a visa, a passport or a driving license. Within the secure document, the security element preferably extends from one edge to the other of the document.

The security element is preferably visible in reflected light within at least one window of the document, as indicated above, which may have a rectangular shape, in particular with a large side perpendicular to the long sides of the document. The length of the window, measured in the direction of the length of the security element, is preferably between 12 and 15 mm.

Within the window, at least two, and preferably three to five zones of different aspects are visible, corresponding to the aforementioned bands of the base film. Conventionally, a security thread extends between the two edges of greater length of a banknote. Thus, the document may have a rectangular shape with long sides and the security element may be a wire that extends between these long sides. The subject of the invention is also a secure document comprising a security thread, in particular obtained by the implementation of a method according to the invention, presenting zones of different aspects which succeed one another in the longitudinal direction of the security thread. and which are each of elongate shape in a direction transverse to the longitudinal direction of the wire, in particular substantially parallel to the long sides of the document, these zones of different aspects or optical effects changing appearance when the direction of observation changes , in particular with a reversal of the aspects between two zones when the direction of observation changes. Each of these zones of different aspects may correspond to a portion of the band of the aforementioned basic film. The invention will be better understood on reading the following detailed description, nonlimiting examples of implementation thereof, and on examining the appended drawing, in which - FIG. embodiment of safety elements by the implementation of an exemplary method according to the invention, - Figure 2 is a sectional view of Figure 1 along II-II, - Figure 3 shows, from the front, an example of a secure document according to the invention, - Figures 4 and 5 illustrate the change in appearance of the wire during a change in the direction of observation, - Figure 6 illustrates an alternative embodiment of the base film, the zones of different aspects are organized in checkerboard, - Figure 7 is a cross section of an example of security thread according to the invention - Figure 8 illustrates different possibilities of cutting son in the base film, - FIGS. 9A to 9C show schematically the son obtained according to the cutouts of Figure 8, and - Figures 10 and 11 show two alternative arrangements of the base film and knives, to obtain obliquely optically active areas. In the figures, the real proportions have not always been respected, for the sake of clarity of the drawing. The method according to the invention implements the cutting of security elements 3 in a base film 40 in a direction of machine direction SM, as shown in dashed lines in FIG. 1. The base film 40 comprises a substrate 50, preferably of a thermoplastic material, such as polyester OEi PET. The thickness t of the substrate 50 is, for example, between 6 and 50 μm. The substrate 50 carries optically active bands of different aspects, which extend in a direction perpendicular to the machine direction, called the transverse direction ST. In the example considered, the substrate 50 carries on the same face a first set of spaced parallel strips 31 and a second set of spaced parallel strips 32, which alternate with the strips 31, with a constant spacing e between the first strips and the strips. second bands, for example of the order of 0.5 mm for a band width of the order of 4 mm. The base film is cut transversely to the strips 31 and 32, preferably perpendicular thereto, to form a plurality of security threads 3 each comprising in the longitudinal direction an alternation of optically active zones respectively from the first and second strips . In the example considered, the strips 31 and 32 are continuous in the transverse direction ST and each of homogeneous appearance over the entire width of the base film 40.

Each band 31 or 32 can be made with different securing means, such as pigments deposited by printing for example, and in particular platelet-shaped magnetic pigments oriented under the effect of a magnetic field.

In the same band, the orientation of the pigments can be the same, and when moving from one band to the next, the orientation of the pigments changes. For example, the base film 40 is unwound a first time to pass to a printing station where the strips 31 are formed using oriented pigments 16, shown schematically in FIG. 2. Then, the base film 40 is returned and returned to the same printing station to form the strips 32 corresponding to the oriented pigments 17. As a result of the reversal of the base film, the pigments 16 and 17 are oriented differently.The film is then cut to form the yarns. 3 which are for example wound on multiple coils.

Impressions 11 may be carried by a face 12 of the substrate 50 opposite that receiving the strips 31 and 32, so as to form when the element 3 is viewed from the front a set of optically active zones 13 and 14 spaced parallel to the strips 31 and 32, the impressions 11 extending below them. The prints 11 can be made using luminescent inks, especially fluorescent inks visible when exposed to ultraviolet radiation. The impressions 11 extend for example in the form of strips of the same width as the strips 31 and 32 or, alternatively, are narrower or wider. In the example illustrated, the optically active zones 13 and 14 provide spaces 15 between them. The prints 11 may be different ink prints, depending on the bands 31 and 32 with which they are superimposed, so as to make UV appear different colors. The pigments 16 and 17 being oriented differently, as illustrated, for an observation direction parallel to the orientation direction of the platelets of the pigment, the underlying impression 11 is visible and for a different direction of observation the pigment is reflective and the underlying impression is not visible. Optically active strips 31 and 32 separated by spaces 15 are thus obtained on the base film, and the change of appearance illustrated in FIGS. 4 and 5 when the observation direction is seen is for example observed on the cut wire 3. changed. In Figure 4, for an observation direction, some areas appear dark and others clear. In Figure 5, it is the opposite, depending on the orientation of the pigments relative to the observer. The prints 11 can be directly made on the substrate 50, as is the case in Figure 2, or in a variant not shown on an intermediate layer, which can protect the prints 11. Thus, the security thread obtained using the method according to the invention may comprise a multilayer support, where appropriate. The pigments 16 and 17 are oriented according to the axis around which the observation direction must turn in order to observe the desired change of appearance. For example, the pigments are oriented, the longitudinal axis of the wire being vertical, respectively to the left and to the right, to obtain a change of appearance when turning the document parallel to this axis. We then have an alternation of appearances of the zones during this rotation. In a variant not shown, the pigments are oriented downwards and upwards, to obtain a change of appearance when the document is rotated about an axis perpendicular to the longitudinal axis. We then have an alternation of appearances of the zones during this rotation. The publication WO 2012/176169 A1 discloses various possible combinations between, on the one hand, oriented magnetic pigments and, on the other hand, the underlying impressions, which may represent more or less complex patterns.

In a general manner, these optically active strips may comprise any means making it possible to obtain an effect of color, brightness and / or perception of a pattern, with the naked eye or under UV or IR. Preferably, it is an effect that varies with the angle of observation, such as that obtained with oriented magnetic pigments.

FIG. 3 shows a secure document 1 according to the invention, for example a banknote, which comprises a substrate 2 and a security thread 3 according to the invention, obtained by cutting the base film 40, as shown in FIG. explained previously. The security film 3 extends between two opposite edges 4 and 5 of the document 1, which are those of greater length.

The security thread 3 may be incorporated at least partially in mass in the substrate 2 of the secure document 1, during the manufacture thereof, in a conventional manner. Any conventional technique of introducing a security thread into windows can be used.

Only part of the wire 3 may be visible in reflected light, for example through one or more windows 6 formed in the substrate 2. An example of incorporation of a security wire into windows is described in the application EP 59056. Each window 6 can expose several optically variable areas 13, 14 of the wire 3.

Preferably, the substrate 2 is fibrous, comprising for example a mixture of natural and / or synthetic fibers, for example cellulose, linen and / or cotton fibers. The substrate 2 may also, alternatively, be made at least partially from a film of a plastics material, for example a bi-stretched polyolefin film such as that marketed under the name Polyart by the Belgian company ARJOBEX Ltd. . In this case, the security element is for example applied to the surface of such a substrate, and held thereon by heat sealing with an adhesive, in particular a thermo adhesive. Alternatively, the base film consists of strips 31, 32 separable from the substrate 50 and applied to the substrate 2 by heat transfer. The wire 3 or the document 1 may comprise other securities of first, second and / or third level, such as those mentioned above. Document 1 may in particular comprise the following additional security elements, used alone or in combination: dyes, luminescent pigments, interference pigments and / or liquid crystal pigments, especially in printed form or mixed with at least one layer constituent of the document, - photochromic or thermochromic compounds, dyes and / or pigments, especially in printed form or mixed with at least one constituent layer of the document, an ultraviolet (UV) absorber, especially in the form coated or mixed with at least one layer constituent of the document, - a specific light-collecting material, for example of the waveguide type, in particular a luminescent light-collecting material such as the polycarbonate-based polymer films marketed by Bayer under the name LISA or a multilayer interference film , a structure with variable optical effects based on pigments interf or a liquid crystal, a birefringent or polarizing layer, a diffraction structure, an embossed image, means producing a "moiré effect", such an effect being able for example to reveal a pattern produced by the superposition of two security elements on the document, for example by the approximation of lines of two security elements, a partially reflective refractive element, a colored filter. a metallized, goniochromatic or holographic foil, a layer with a variable optical effect, based on interferential pigments or liquid crystals, a flat and relatively small security element such as a board, visible or non-visible, in particular luminescent, with or without an electronic device, particles or agglomerates of pigment particles or dyes of HI-LITE type, visible or non-visible, in particular luminescent, security fibers, in particular metallic fibers, magnetic fibers (with soft and / or hard magnetism), or absorbing fibers , or excitable to ultraviolet, in the visible or the infrared, and in particular the near infrared (NIR), an automatically readable security having specific and measurable characteristics of luminescence (for example fluorescence, phosphorescence), absorption of light ultraviolet, visible or infrared), Raman activity, magnetism, microwave interaction, X-rays or electrical conductivity. At least one of the constituent layers of document 1 may comprise a first level security element such as a watermark or a pseudo-watermark. The security thread can be superimposed at least partially on such a watermark. In the example of FIG. 3, the width w of the wire 3 is preferably greater than the width 1 of the strips 31 and 32, so that they form on the wire, after cutting, zones of homogeneous aspects of rectangular shape of large sides parallel to those of the document. In the variant illustrated in FIG. 6, each strip 31 of the base film is itself subdivided into portions 71 and 73, and each strip 32 in portions 72 and 74 with a longitudinal offset chosen so that the arrangement of the different portions 71 to 74 on the base film 40 form a checkerboard. In Figure 6, all portions 71 to 74 are formed with oriented magnetic pigments. The magnetic pigment particles within each band portion 71 to 74 all have substantially the same orientation.

The band portions 71, 74 have substantially all the same first orientation and the band portions 72, 73 have substantially all the same second orientation, so that for a given viewing direction, a checkerboard appearance is observed, the boxes change their appearance and for example go from light to dark or vice versa, when we change the direction of observation.

Preferably, as illustrated, the spacing d between two successive portions of the same band 31 or 32 is greater than the length g, measured in the transverse direction ST, of these. We have for example 1/20 cl / g <'h. Each square of the checkerboard is for example of rectangular shape, with a large side parallel to the machine direction SM.

The son 3 are for example cut according to the dashed lines of Figure 6, half width of the boxes. The security threads 3 cut along the machine direction SM in the base film of FIG. 6 may be sufficiently wide to integrate several columns of boxes in the direction of the width.

In the case of a security thread 3 accommodating three portions of the same band 31 or 32 in the width direction, each portion comprising oriented magnetic pigments, the orientation of each portion belonging to the central column may be intermediate between those portions of the other columns situated on the same line and arranged on either side of them, as shown in Figure 7, so that when we change the direction of observation, there is a visual effect of transition between the different portions which is more progressive. In the example of FIG. 7, the central optically active zone 14 of the wire 3 has magnetic pigments oriented perpendicular to the substrate 50 and the optically active lateral zones 13a and 13b situated on either side of the central zone 14 of the orientations. respectively to the left and to the right. It is possible to obtain a transition effect corresponding to a zone of clear aspect of the wire which moves from one side to the other. In the case of impressions underlying the pigments, such a gradation of the orientations can also make it possible to generate a movement effect, by making it possible to successively see the underlying impressions at different locations of the wire when the direction of observation changes. The use of discontinuous strips with portions of different aspects arranged "checkerboard" may allow to obtain a variety of security son from the same base film, by varying the position during cutting, knives used.

Figure 8 illustrates three different cutout configurations of the same base film, leading to different security threads, shown in Figures 9A, 9B, and 9C respectively. The first cutting configuration is obtained by positioning the knives so that, according to the lines C1, they cut each strip in the middle of a solid portion 71 and 72, or 73 and 74. A safety thread is then obtained. as illustrated in FIG. 9A, comprising a succession of pairs of half-portions belonging to as many respective bands when they are traversed longitudinally, and two half-portions of the same band when they are traversed transversely, according to T. for example. The lines C2 thus pass between the portions 71 and 73 for a band 31 and between the portions 72 and 74 for a band 32. The second cutting configuration is obtained by positioning the knives along the lines C2 so that they cut each strip between two strip portions. The lines C2 thus pass between the portions 71 and 73 for a strip 31 and between the portions 72 and 74 for a strip 32. A security thread is obtained as illustrated in FIG. 9B, comprising a succession of portions each belonging to to a different band when traversed longitudinally, and a single portion of band when traversed transversely, according to T for example. Finally, the third cutting configuration is achieved by positioning the knives along the lines C3 so that they cut each strip between two strip portions, the lines C2 being spaced apart so that there is a knife disposed between every other portion of each band. The lines C3 are thus combined with one line on two of the lines C2. A security thread is obtained as illustrated in FIG. 9C, comprising a succession of pairs of portions belonging to as many respective bands when they are traversed longitudinally, and two portions of the same band when they are traversed transversely. , according to T for example.

It may be desirable to seek safety son 3 having optically active oblique zones, each having for example a median axis oriented obliquely to the longitudinal direction of the wire. In order to achieve this, one can start from a base film as described above and orient the knives obliquely. The machine direction SM is then no longer parallel to the edges of the base film, as in the case illustrated in FIG. 11. In a variant, the same result can be obtained by arranging the strips 31, 32 obliquely relative to an edge of the base film, using techniques similar to those previously described for applying the strips to the base film. A different base film is then obtained, but it is not necessary to modify the orientation of the knives: the machine direction SM can remain parallel to one of the edges of the base film, as shown in FIG. Inclination α between the central axis of the strips 31, 32 and the direction of the knives is, for example, between 30 and 90 ° (excluding the end), preferably between 60 and 90 ° (the end is excluded). The strips of different aspects can be made with other means than orientable magnetic pigments, for example, the strips can be made with interferential pigments, in particular goniochromatic pigments, or with lenticular networks. The optically active strips are preferably made on the same substrate face, alternatively, the strips are produced on the two opposite faces of the substrate, for example the strips 31 of the example of FIG. cto of the substrate and the strips 32 on the back of the substrate. The strips made on the base film can be of more than two kinds. For example, we have k different types of bands that follow each other in the machine direction SM, with all possible combinations between them. The cutting can be carried out, if necessary, with a variable width, or obliquely with respect to the strips, when these are printed obliquely with respect to the transverse direction. Thus, it should be understood by transverse cutting strips a cut with an orientation not strictly parallel to the strips, preferably perpendicular to them, but can also make a non-right angle with the direction of the strips. The strips can be made with a variable width.

The security thread may receive one or more impressions that extend continuously in the machine direction SM or a band having a microtext, in particular formed by metallization / demetallization.

Claims (38)

REVENDICATIONS1. A method of manufacturing a longitudinally elongated secure security element (3) for secure document having in the longitudinal direction a succession of optically active zones, said method comprising the steps of: a. performing on a substrate (50) a succession of generally parallel optically active strips (31, 32), so as to form a base film (40), b, cutting the security element (3) in the base film in a direction (SM) generally transverse to the bands. 2. Manufacturing method according to the preceding claim, the optically active strips (31, 32) having first strips (31) alternating with second strips (32), the first and second strips having distinct optical aspects and / or effects. when observed simultaneously in reflected light in at least one direction of observation. 3. Manufacturing method according to claim 2, the first and second strips being made such that: a. In a first viewing direction of the base film (40) the first and second strips have different aspects, and b. in a second direction of observation different from the first, the first and second strips have each changed appearance and the first bands have a different appearance than the second bands. 4. The manufacturing method according to claim 2 or 3, the first (31) and second (32) strips being made such that: a. in a first direction of observation of the base film (40) the first bands appear of a first aspect, appearing in particular colored, reflective, opaque, transparent, semi-transparent or matte, and the second bands appear of a second aspect , different from the first aspect, appearing in particular colored, reflective, opaque, transparent, semi-transparent or matte, b. in a second direction of observation of the base film, different from the first direction, the first bands appear with the second aspect and the seconds with the first aspect, in particular with the following combinations: first matt appearance and second reflective appearance or conversely, - first and second aspects of different colors, - first transparent or semi-transparent appearance and second opaque appearance. 5. The manufacturing method according to any one of the preceding claims, the optically active strips (31, 32) comprising magnetically oriented pigments. 6. Manufacturing method according to the preceding claim, the magnetically oriented pigments (16; 17) - present within the same band (31; 32) having substantially all the same orientation. 10 7. Manufacturing method according to any one of the preceding claims, two adjacent bands being separated by a gap. 8. The method of claim 7, the substrate carrying a security element visible at least partially in said gap. 9. The manufacturing method according to any one of the preceding claims, each strip having a lenticular array. 10. The manufacturing method according to the preceding claim, each network comprising convex lenses, in particular substantially hemispherical lenses. 11. The manufacturing method as claimed in any one of the preceding claims, the optically active zones of the security element being oblique, each zone preferably having an inclination with respect to the longitudinal direction of the security element lying between and 90 ° (excluding terminal), better still between 60 and 90 ° (excluding the terminal), the inclination being obtained in particular by making the strips obliquely on the base film and by cutting parallel to an edge of the base film or by realizing the strips parallel to an edge of the base film and cutting in an oblique direction relative to this edge. 12. The manufacturing method according to any one of the preceding claims, the width (1) of the optically active strips (31, 32) being between 1 and 10 mm, preferably between 2 and 5 mm. 13. Manufacturing method according to any one of the preceding claims, the spacing (e) between two bands (31, 32) optically active being always substantially the same. 22 3020987 14. The manufacturing method according to any one of the preceding claims, the spacing (e) between two optically active bands (31, 32) being between 0.1 and 3 mm, better between 0.4 and 1 mm. 15. The manufacturing method as claimed in any one of the preceding claims, the width (40) of the cut-off security element (3) being between 1 and 10 mm, better still between 3 and 5 mm. 16. Manufacturing method according to any one of the preceding claims, the security element (3) being a security thread. 17. The manufacturing method according to any one of the preceding claims, the substrate (50) comprising polyethylene terephthalate. 18. The method according to any one of the preceding claims, the optically active bands being optically variable. 19. The manufacturing method according to any one of the preceding claims, each strip (31, 32) having a succession of portions (71, 73; 72, 74) having distinct optical properties. 20. Manufacturing method according to the preceding claim, the spacing (d) between two portions (71, 73; 72, 74) of successive bands of the same band being between 0 and 10 mm. 21. The manufacturing method according to one of claims 18 or 19, the portions (71, 72; 73, 74) of the same band (31, 32) having substantially all the same length (g). 22. Manufacturing process according to the preceding claim, the length (g) of a band portion being between 1 and 10 mm. 23. The manufacturing method according to any one of claims 18 to 21, the strip portions comprising oriented magnetic pigments, the pigments within the same band portion (71, 72; 73, 74) having substantially all the same orientation. 24. The method of manufacture according to the preceding claim, portions whose pigments have substantially all the same first orientation being arranged alternately with other portions whose pigments have substantially all the same second orientation, so as to form a checkerboard on the base film (40). 23 3020987 25. Manufacturing method according to any one of claims 18 to 23, the security element (3) having a width (w) greater than the length (g) of a band portion. 26. A method according to any one of the preceding claims, the optically active strips being discontinuous and each formed by an alternation of portions having distinct optical properties, with an offset between two successive bands so that said portions are disposed on the film according to a checkerboard arrangement and in which the elements are cut in at least one of the following ways, with for example two separate films, respectively cut in two of them: the security elements are cut (Cl) in intersecting at mid-length two successive portions of a band, the security elements are cut (C2) by cutting between successive portions of a band, the security elements are cut (C3) by cutting between each pair of successive portions of a band. 27. Base film for producing a security element by cutting the base film in a machine direction, comprising: - a substrate, a succession of optically active strips carried by the substrate generally parallel, and generally oriented transversely to the direction machine. 28. Base film according to claim 27, the optically active strips being discontinuous and each formed by an alternation of portions (71,73; 72,74) having distinct optical properties, with a gap between two successive strips of such said portions are disposed on the film in a checkerboard arrangement. 29. The film of claim 27, the portions of a strip being non-contiguous. 30. Film according to claim 27 or 28, the strips (31,32) being spaced from each other in the machine direction. 30 31. Security element obtained by a method according to any one of claims 1 to 25. 32. Elongated security element, for secure document, having in the longitudinal direction a succession of optically active zones. 24 3020987 33. The security element according to claim 31 or 32, the optically active zones comprising oriented magnetic pigments, two optically active zones having magnetic pigments oriented differently with the appearance or disappearance of a reflection during a rotation of the element. relative to the observer around a transverse axis of rotation, in particular perpendicular to the longitudinal axis of the security element. 34. The security element according to claim 31 or 32, the optically active zones comprising oriented magnetic pigments, two optically active zones having magnetic pigments oriented differently with the appearance or disappearance of a reflection during a rotation of the element. relative to the observer about an axis of rotation parallel to the longitudinal axis of the security element. A security element according to any one of claims 31 to 34, including a longitudinal alternation of pairs of adjacent portions, having distinct optical properties, with a checkered pattern of said portions on the wire, each portion having preferably a rectangular shape of large side parallel to the longitudinal direction of the element or alternatively perpendicular to said direction. 36. Secure document comprising a security element (3) according to any one of claims 31 to 35. 37. Secure document according to the preceding claim, the security element (3) being a security thread inserted into window (s) in a substrate. 38. Secure document (1) comprising a security thread (3), in particular obtained by implementing the method according to any one of claims 1 to 25, having zones of different aspects or optical effects that succeed in the longitudinal direction of the security thread and which are each of elongate shape in a direction transverse to the longitudinal direction of the wire, in particular substantially parallel to the long sides of the document, these areas of different optical aspects or optical effects changing from aspect when the direction of observation changes, including a reversal of the aspects between two areas when the direction of observation changes.