EP3109060B1 - Safety element and method for manufacturing a safety element - Google Patents

Description

The invention relates to a security element and to a method for producing a security element, in which a flexible substrate is provided with a luminescent layer at least in regions and in a further step a diffraction structure is produced by embossing the luminescent layer in such a way that the luminescence intensity of the layer depends on the Viewing angle on this layer changed visually recognizable.

Multilayer security elements are known from the prior art ( WO2011 / 042010A1 . DE102010108170A1 ), which achieve a dependence of a luminescence intensity on the viewing angle by providing a layer with a diffraction structure on a luminescent layer. Disadvantageously, such laminates have a high background luminescence, which disturbs the optical recognizability of the dependence of the luminescence intensity on the viewing angle and thus jeopardizes the security function of the security element. Therefore, narrow process parameters usually have to be followed in order to ensure comparatively high reproducibility in the production of the security element.

In addition, from the prior art ( WO2008 / 095481A2 Security elements are known which have a photonic crystal in a luminescent layer, which forms a diffraction structure. A disadvantage is required for the production of a photonic crystal of a multi-stage process, in which first the photonic crystal has to be generated in a separate step and then connected to the other means of the security element. In addition, the generation of a photonic crystal is comparatively complicated and complex, because, for example, under the action of pressure and heat, a layer must be compacted, which the Contains particles for forming the photonic crystal. Such methods therefore usually show a comparatively low reproducibility. A prior art according to the preamble of claim 1 is known from US2012 / 0068450A1 known.

It is therefore the object of the invention to provide a method for producing a security element in a simpler and cheaper, but nevertheless reproducible way.

The invention achieves the stated object with regard to the method by the features of claim 1.

If the luminescent layer is embossed in order to produce the diffraction structure, the security element can be produced comparatively quickly and procedurally in a simple manner. In contrast to a multi-layer structure known from the prior art, a single applied layer can now be sufficient to allow both the optical radiation or luminescence and the diffraction structure for the angle-dependent change in the luminescence intensity. In particular, however, the invention may be distinguished by the fact that the possibility of adjusting the background luminescence over the depth of the embossing or correspondingly minimizing it with the embossing of the luminescent layer in order to compensate for process fluctuations and manufacturing tolerances. The inventive method can therefore reproducibly always ensure good visual recognition and thus high security against forgery of the security element. In this context, it is mentioned that by the integration of the luminescent substances directly in the diffraction structure, a slightly visually recognizable change in the luminescence intensity as a function of the viewing angle-with simultaneously low background luminescence-can be produced.

In general, it is mentioned that the luminescent layer can be a liquid curable lacquer or even a thermoplastic material, which material can be provided with an embossed structure by forming with an embossing tool and by the action of pressure and / or temperature and / or electromagnetic radiation, for example UV radiation. This can also be, for example, a hot stamping process.
In general, it is further noted that a luminescent layer can be any layer based on thermoplastic polymers such as PMMA, acrylates, PVC, PU or similar materials. A luminescent layer may further consist of free-radically or cationically curable UV lacquers which are based inter alia on polyester, PU or acrylate binders.
In general, it is further mentioned that, in addition to the partially applied, embossed, luminescent layer, it is also possible to apply further layers in regions. For example, it is conceivable that a non-luminescent layer having a diffraction structure can additionally be applied to the substrate and embossed to produce the diffraction structure, wherein the embossing of the non-luminescent layer can optionally be effected separately or together with the luminescent layer.
In general, it is further stated that the luminescent substances contained in the layer can be, for example, organic fluorescent dyes which emit light in the visible spectral range upon excitation with UV radiation. A disadvantage of such materials is that they usually have a low light fastness, ie, the fluorescence intensity under continuous irradiation - such as sunlight - decreases rapidly. Better light fastness can be achieved with inorganic, fluorescent pigments. Disadvantageously, such pigments have high pigment sizes, whereby visible light is scattered on the pigments. Such layers usually appear opaque to the viewer. Nanocrystalline materials, on the other hand, can combine the advantages of organic fluorescent dyes with the better lightfastness of pigments. Fluorescent nanoparticles based on compound semiconductors, which usually have particle sizes of 10-50 nm, have proven to be particularly suitable, whereby scattering of the visible light on the particles can be avoided. Prefers Such nanoparticles consist of CdSe, PbS, ZnS, ZnO or other comparable materials. To further increase the luminescence efficiency, the nanoparticles can be designed as core-shell particles. In addition, to improve the solubility in the layer, the surface of the nanoparticles can be functionalized.

The process can be accelerated if the luminescent layer is applied to the substrate in a liquid or pasty manner, embossed and cured. In addition, a liquid or pasty application, preferably coating, can react extremely flexibly to changing process parameters, which can increase the reproducibility of the process. Furthermore, this application reproducibly produces a stable cohesive connection.

A diffraction structure following a tight manufacturing tolerance can be produced when the luminescent layer is cured during embossing. In addition, the curing of the luminescent layer is thus comparatively easily controlled, which can benefit the reproducibility of the method.

The method can be further simplified if the luminescent layer is cured by radiation, in particular by UV radiation. Preferably, the flexible substrate is permeable to this radiation, whereby irradiation of the luminescent layer through the substrate can take place. In this case, it can be avoided in particular that the embossing tool shadows the layer and thus uncontrollably influences the hardening of the layer, depending on the position.

If a luminescent in at least two different colors layer is applied to the flexible substrate, the security against counterfeiting of the security element can be further improved. Thus, not only a change in the luminescence intensity, but also a color change effect depending on the viewing angle can be visually recognized on the security element. Beyond that In addition, the wavelengths of the luminescent colors and the size of the diffraction structures are tuned to each other, the color mixing ratio can be set advantageously for each viewing angle.

The process can be accelerated if a liquid paint is mixed with at least one luminescent substance and applied as a luminescent layer on the substrate. Such a fluorescent varnish can not only be made comparatively easy, but also provide for a mechanically particularly stable cohesive connection with the flexible substrate, which can significantly increase the reproducibility of the process.

A continuous process may be enabled if the luminescent layer is embossed with a rotating embossing tool. In addition, a nearly bump-free embossing of the layer can be ensured, which can greatly facilitate the process.

The reproducibility of the method can be further increased if a cover layer is applied to the embossed, luminescent layer. By way of example, this cover layer may be a protective lacquer layer which is at least partially transparent to the luminescent color in order to be able to precisely follow not only the diffraction structure of the luminescent layer, but also to reduce the intensity of the luminescence as little as possible. This cover layer can also be an adhesive layer in order to be able to provide the security element in a handling-friendly manner on a document of value. Such an adhesive layer can be, for example, a pigmented or pigment-free heat-sealable, cold-seal or self-adhesive coating. The adhesive layer may also be additionally applied to an existing protective lacquer layer. In addition, optionally, a reflection layer can be applied beforehand. To form a reflection layer, a metal is conceivable.

Preferably, the flexible substrate is peeled off the security element to provide a slim designed security element. This can be the case in particular after the security element has been laminated on a value document.

In general, it is mentioned that the luminescent layer can be applied to the flexible substrate in a roll coating process. This ensures a particularly high degree of homogeneity in the application of the luminescent layer. This may be particularly advantageous in the subsequent embossing step, since the roller application method increases the reproducibility of the method and at the same time ensures a more uniform impression of the embossed structure in the luminescent layer. A uniform impression of the embossed structure can in turn accelerate the process and increase the throughput, since the time required for complete molding of the embossed structures can be reduced.

In general, it is further mentioned that the luminescent layer can be applied to a flexible substrate designed as a plastic film. This can be compared to the prior art, thinner and more flexible security element can be generated. For this plastic film, a PET, PP, PC, PEN, PMMA, PVC or PE material may be suitable. In addition, it is also possible to provide a transparent substrate with which the cohesive bonding with the luminescent layer can be facilitated.

It is also an object of the invention to constructively simplify a security element of the type described, but nevertheless to ensure a high security against counterfeiting.

The invention achieves the stated object with regard to the security element by the features of claim 10.

Because the luminescent layer has an embossing structure which forms the diffraction structure, both the change in the luminescence intensity dependent on the viewing angle and the luminescence itself can be structurally simply contained in a single layer and thus adjusted extremely precisely to one another. In addition, it is possible to dispense with a multilayer structure known from the prior art in order to produce a change in the intensity of luminescence-which can avoid disturbing background luminescence. According to the invention, this can thus lead to a security element whose change in the luminescence intensity is visually clearly recognizable, which can lead to a high security against counterfeiting. In addition, the security element can be produced less expensively by the single-layer solution in order to create a diffraction structure which interacts with the luminescent layer to visually detectable change in the luminescence intensity as a function of the viewing angle on the luminescent layer.

In general, it is mentioned that the security element can be used to secure against forgery of a value document, in particular a banknote, a credit card, a passport, an identity card or the like.
In general, it is further mentioned that the security element can be suitable for embedding in a value document in the form of a thread, in the form of a strip or in the form of a fabric.
It is also generally mentioned that the security element can have additional security features, such as diffractive layers, liquid-crystalline layers, layers with optical features, or layers with electrically conductive or magnetic features. Thus, the security against counterfeiting of the security element is additionally improved. Layers with optical features may in this context be, for example, additional colored layers or luminescent layers.

The security against forgery of the security element can be further increased if the luminescent layer luminesces in at least two different colors. For this purpose, the luminescent layer can have a change in the luminescence intensity which is dependent on the viewing angle for each luminescent color. The viewing angle having the maximum luminescence intensity can here be determined by the wavelength of the respective luminescence color and the diffraction structure size. By mixing the different luminescent colors can thus be set a very tamper-proof color change effect.

If the luminescent layer has a lacquer with a luminescent substance, homogeneous luminescence over the surface of the luminescent layer can be made possible. In addition, a particularly accurate diffraction structure can be constructively and procedurally easily generated in a paint, which makes it possible to further improve the security against forgery of the security element. In this case, it may be particularly advantageous if the luminescent layer has a radiation-curing, preferably UV-crosslinking, lacquer.

Fig. 1

eine schematische Darstellung einer Vorrichtung zur Herstellung eines Sicherheitselements nach einem ersten Ausführungsbeispiel,

Fig. 2a

eine Schnittansicht durch das nach Fig. 1 hergestellte Sicherheitselement,

Fig. 2b

eine Schnittansicht durch ein Sicherheitselement nach einem zweiten Ausführungsbeispiel,

Fig. 3

eine Schnittansicht durch ein Sicherheitselement nach einem nicht erfindungsgemäßen Ausführungsbeispiel,

Fig. 4

eine Schnittansicht durch ein Wertdokument mit einem aufgebrachten, nicht erfindungsgemäßen Sicherheitselement und

Fig. 5

eine schematische Draufsicht auf eine Prägestruktur eines Sicherheitselements.

Stability and life of the security element can be significantly improved if it has a cover layer, which cover layer covers the embossed structure. In this case, it can prove to be particularly advantageous if the cover layer is a protective lacquer layer which is at least partially translucent for a luminescent color and thus protects the security element against external influences, such as mechanical or chemical stresses. This cover can also be used to achieve an airtight termination of the luminescent layer and thus to prevent aging, for example by oxidation under UV radiation. Preferably, a radiation-curing protective lacquer layer can further improve these above advantages. This cover layer may alternatively or additionally also have an adhesive layer, in particular a self-adhesive coating, in order to be able to laminate the security element in an easy-to-handle manner on a value document. In addition, between luminescent layer and cover layer if appropriate, a reflection layer can be provided in order to further increase the security against counterfeiting. This reflection layer may be about a full-area or partial layer of metals, metal alloys, metal compounds or an inorganic layer of metal oxides or sulfides, such as TiOx, SiO, ZrO2, ZnS. If the security element has a flexible substrate on which the luminescent layer is provided, the stability and stability of the security element can be further increased. In addition, the security element can be handled more easily in this way and can be provided more reproducibly on a document of value. According to the invention, the embossed structure penetrates the luminescent layer. In this way, the background luminescence can be reduced to a minimum, which in turn increases the visual recognition of the change in the luminescence intensity with the viewing angle and, finally, can improve the security against forgery of the security element.
The security element according to the invention can develop its advantages in particular if it is used in a value document, in particular a banknote, passport, driver's license or identity card.
In the figures, for example, the subject invention is illustrated in more detail with reference to several embodiments. Show it

Fig. 1

a schematic representation of an apparatus for producing a security element according to a first embodiment,

Fig. 2a

a sectional view through the Fig. 1 manufactured security element,

Fig. 2b

a sectional view through a security element according to a second embodiment,

Fig. 3

a sectional view through a security element according to a non-inventive embodiment,

Fig. 4

a sectional view through a document of value with an applied, non-inventive security element and

Fig. 5

a schematic plan view of an embossed structure of a security element.

According to the Fig. 1 schematically shown device 100 for producing a security element 1 can be seen that a flexible substrate 2 is at least partially provided with a luminescent layer 3 and these are connected to one another cohesively. This can be done by all common coating methods, according to Fig. 1 also be carried out with a coating method 4, in which with a slot die a uniform layer 3 is generated or applied to the substrate 2. Alternatively - but not shown - this is also a roller application process conceivable.

According to the invention, in a further step, this applied luminescent layer 3 is embossed by means of an embossing tool 5 in order to produce a diffraction structure 6. By means of this diffraction structure 6 in cooperation with an excited own radiation of the luminescent layer 3, a change in the luminescence intensity which can be visually recognized as a function of the viewing angle 10 on the layer 3 can be created - which is particularly evident in the US Pat Fig. 2 is shown. Namely, light beams 7 emitted in the region of the diffraction structure 6 interfere with each other on exiting the diffraction structure 6. This interference leads to a weakening or amplification of the luminescence - depending on the exit angle 8. For the observer 9, this results in a tilting effect in which the luminescence intensity varies as a function of the viewing angle 10. This luminescence can be excited and generated by suitable radiation, preferably by UV radiation. If the security element 1 is illuminated with white light, in particular with light from the visible wavelength range, then the white light is split into its color components as a function of the angle, and the observer 9 can perceive different, reflected colors as a function of the viewing angle.

As in Fig. 1 shown, in addition to the partially applied luminescent layer 3 also other layers 3 'can be applied in some areas. It would be conceivable in this context that, for example, non-luminescent layers or luminescent layers equipped with another luminescent color are applied. It is also conceivable that no layer 3 'is applied to the flexible substrate 2.

As in Fig. 1 1, a starting material 12 with, for example, two luminescent substances 13, represented by different particles 13, is mixed to form the luminescent layer 3. The mixture 14, which in Fig. 1 is applied by means of a coating method 4 on the flexible substrate 2 and, accordingly, the luminescent layer 3, then have a plurality of luminescent colors. This results in how in Fig. 2a shown, independently for each luminescence color depending on the viewing angle 10 attenuation or amplification of the respective luminescence intensity. The security against forgery and recognizability of the security element 1 can accordingly be improved, since 8 different luminescent colors are perceived at different viewing angles.

As in Fig. 1 For the formation of the luminescent layer 3, a liquid, hardenable lacquer 12 with luminescent substances 13 is homogeneously mixed and this mixture 14 is applied to the flexible substrate 2. As described above, luminescent substances 13 are added to the liquid paint 12 at different wavelengths. To form the diffraction structure 6, the applied liquid paint 12 is embossed with an embossing tool 5 and activated in a further step, the curing process of the luminescent layer 3 and the varnish 12, whereby this polymerized and the diffraction structure 6 steadily preserved.

The activation of the curing process takes place during embossing with the embossing tool 5, since the embossed layer 3 can be more easily detached from the embossing tool 5 after at least partial polymerization. It is both conceivable that the polymerization after embossing is already completely completed, as well as that the liquid layer 3 has been pre-gelled or the curing process has been activated before embossing.

For hardening the luminescent layer 3, a radiation source 15 can be used. The use of UV radiation 16 has proven to be particularly simple and thus advantageous in this context. If a transparent substrate 2 is used, at least for the radiation 16, the irradiation of the luminescent layer 3 can take place through the substrate 2. This offers procedurally great advantages, since in this case the embossing tool 5 does not shade the radiation 16 and thus a more homogeneous and larger-area irradiation of the luminescent layer 3 is possible. It is also conceivable to provide additional radiation sources before and after the embossing step in order to carry out a pre or postpolymerization of the layer 3. When using a UV-transparent embossing tool 5 (made of quartz glass or a corresponding polymer), the curing by UV radiation 16 through the embossing tool 5 can take place. The UV radiation source 15 could in this case be mounted in the middle of the embossing tool 5.

This in Fig. 1 In the case of an advantageous embodiment of the invention, the application method 4 of the luminescent layer 3 shown as a slot die can be a roller application method. Such a method can be distinguished, in particular, by the fact that very homogeneous layers can be produced therewith. A homogeneous luminescent layer 3 is advantageous, in particular for the subsequent embossing step, because a more uniform impression of the embossed structure 20 is thereby possible. The homogeneity of the luminescent layer 3 also has an effect on the contact time of the stamping tool 5 with the layer 3, since the time required for the impression of the stamping structure 20 is reduced and thus the throughput of the entire method can be increased.

As in Fig. 1 shown, the luminescent layer can be embossed with a rotating embossing tool 5. In this case, the security element 1 can be moved continuously during production. This is particularly advantageous in roll-to-roll manufacturing processes where a continuous manufacturing process is desired. In addition, a rotating embossing tool 5 has the advantage that successive embossings can be performed almost bum-free and make expensive alignment procedures of the embossing tool unnecessary.

In an advantageous embodiment of the invention, the luminescent layer 3 can be applied, in particular, to a substrate 2 designed as a plastic film. Such a substrate can in particular serve to improve the cohesive connection to the applied layer 3 and additionally provide good light transmission for the UV radiation 16 used for the curing.

To protect the security element 1 and to increase its service life, a cover layer 17 is applied to the embossed luminescent layer 3 with a common application method 18. This cover layer 17 is after Fig. 3 applied as a protective lacquer layer 19 on the luminescent layer 3. In any case, this protective lacquer layer 19 must be transparent to the luminescent colors contained in the luminescent layer 3. However, it is conceivable that the light transmission is limited to certain subregions of the protective lacquer layer 19 in order to incorporate luminescent shapes or patterns in the security element and thus to further increase the security against counterfeiting.

In order to provide a security element 102 on a value document 22 or another carrier, as in Fig. 4 to recognize, as a cover layer 17, an adhesive layer 23 applied to the security element 102, the opposite to the security element 101 after Fig. 3 is shown turned upside down. This can be done with a common application method 18, for example, instead of the protective lacquer layer 19. Thereafter, the security element 102 can be adhesively bonded by means of the adhesive layer 23 to the value document 22 and in a further step the flexible substrate 2 away from the security element 102, in particular peeled off. This process was in Fig. 4 indicated. The removal of the flexible substrate 2 can be facilitated inter alia by the application of a Haftverminderers, in particular a release layer, between the flexible substrate 2 and luminescent layer 3, which is not shown in more detail in the figures.

The various security elements 1, 101, 102 produced according to the described method will now be described in more detail.

According to Fig. 2a is shown that the security element 1 has a luminescent layer 3, which in turn has a diffraction structure 6 for visually recognizable change in the luminescence intensity as a function of the viewing angle 10. In the region of the diffraction structure 6 emitted light beams 7 interfere with similar light beams 7 depending on the exit angle 8 constructive or destructive. This leads to a viewing angle-dependent amplification or attenuation of the luminescence. This results in a tilting effect with respect to the luminescence for the viewer 9. Particularly advantageously, the diffraction structure 6 is designed as an embossed structure 20. This allows a procedurally simple and fast introduction of the diffraction structure 6 in the luminescent layer 3. In addition, the background luminescence can be regulated via the embossing depth 21 and thus always particularly high security against counterfeiting can be ensured. Fig. 3 shows by way of example a security element 101 with an embossing depth 21 of the embossed structure 20, which does not completely penetrate the luminescent layer 3.

According to the FIGS. 2a, 2b . 3 and 4 For example, all security elements 1, 101, 102 have a flexible substrate 2 on which the luminescent layer 3 is applied. This can be of great advantage, in particular when handling the security element in the method steps, and considerably simplify this. However, if necessary, the flexible substrate 2 can be removed again from the luminescent layer 3 in a further step.

In a particularly advantageous embodiment of the invention, the luminescent layer 3 has at least two different luminescent colors. Each luminescent color has its own viewing angle dependence of the luminescence intensity. This viewing angle dependence follows from the interference condition as a function of the respective luminescence wavelength and the diffraction pattern size 11. By overlaying all the luminescent colors, a color play which is dependent on the viewing angle 10 results, in which each viewing angle 10 can be assigned a unique mixed color.

As in the FIGS. 2a and 2b The embossing structure 20 according to the invention is designed in such a way that it penetrates the luminescent layer 3. Here, the embossing depth 21 corresponds to the thickness of the luminescent layer 3. This may prove to be advantageous because it minimizes the background luminescence and the detectability of the change in the luminescence intensity can be improved. This in turn is conducive to the security against forgery of the security element.

Alternatively, in Fig. 3 a security element 101 not according to the invention is shown, in which the embossed structure 20 does not completely penetrate the luminescent layer 3, ie the embossing depth 21 is smaller than the thickness of the luminescent layer 3. Unlike the embodiments in Fig. 2a and 2b Thus, light is also emitted in the deep regions of the embossed structure 20. The clear recognition of the different emissions at different viewing angles, however, can be somewhat affected.
The in the Fig. 2a and 2b shown luminescent layers 3, are designed in one embodiment as a radiation-curing, in particular UV-crosslinking paint. This is particularly advantageous from a procedural point of view since such a lacquer layer 3 can be easily embossed and polymerized or hardened by UV radiation 16 in order to produce an embossed structure 6 (cf. Fig. 1 ).

As in Fig. 2b In order to protect the security element 1, in one embodiment of the invention, a cover layer 17 is applied to the embossed structure 20. This cover layer 17 is designed in particular as a transparent, radiation-curing protective lacquer layer 19. In any case, the applied covering layer 17 must be transparent to the luminescent colors and to the exciting radiation. Such a cover layer 17 can improve the life of the security element 1 and its resistance to external influences. It is thus possible, for example, to protect the luminescent layer 3 from oxidation caused by UV radiation.

According to Fig. 3 the embossed structure 20 has a metallic reflection layer 24 in regions. This reflection layer 24 is applied directly to the embossed structure 20 of the luminescent layer 3 and preferably has a homogeneous thickness.

In Fig. 4 In addition, a security element 102 is shown which is provided with an adhesive layer 23 on the side opposite the flexible substrate 2. In this case, the adhesive layer 23 is applied directly to the luminescent layer 3 or to the reflection layer 24 applied to the luminescent layer 3. The security element 102 is at the same time adhesively connected via the adhesive layer 23 to a value document 22, the flexible substrate 2 having been detached from the security element 102 after the security element 102 has been connected to the value document 22. The adhesive layer 23 may in this case be designed in particular as a self-adhesive coating.

In Fig. 5 In particular, a top view of the security elements 1, 101, 102 is shown, wherein the two-dimensional embossed structure 20 is shown in the form of circles. The circles thus include areas of the luminescent layer 3, while outside of the circles no luminescent layer 3 is present and thus a view of the value document 22 is released. In particular, it can be seen here that the periodicity 25 of the embossed structure 20 differs in the longitudinal direction 26 of the periodicity 27 of the embossing pattern 20 in the transverse direction 28. This difference causes the interference condition for the amplification or extinction of the emitted light in these two directions 26, 28 to also be different. So you tilt a security element 1 according to Fig. 5 along the tilting directions 26 and 28 shown, this results in different optical effects. This mechanism again significantly increases the security against forgery of the security feature 1 according to the invention.

Claims (15)

1. Method for manufacturing a security element, wherein a flexible substrate (2) is provided in at least some areas with a luminescent layer (3), and in a further step a diffractive structure (6) is produced in such a way by embossing the luminescent layer (3) that the luminescence intensity of the layer (3) as a function of the viewing angle (10) to this layer (3) is visually appreciably altered, characterized in that the luminescent layer (3) is penetratively embossed to create the diffraction structure (6).
2. Method according to claim 1, characterized in that the luminescent layer (3) is applied to the substrate (2) as a liquid or a paste, embossed and cured.
3. Method according to claim 2, characterized in that the luminescent layer (3) is cured during the embossing.
4. Method according to claim 2 or 3, characterized in that the luminescent layer (3) is cured by radiation (16), more particularly by UV radiation (16).
5. Method according to any one of claims 1 to 4, characterized in that a layer (3) the luminescing in at least two different colours is applied to the flexible Substrate (2).
6. Method according to any one of claims 1 to 5, characterized in that a liquid varnish (12) is mixed with at least one luminescent sustance (13) and applied to the substrate (2) as a luminescent layer (3).
7. Method according to any one of claims 1 to 6, characterized in that the luminescent layer (3) is embossed with a rotating embossing tool (5).
8. Method according to any one of claims 1 to 7, characterized in that a covering layer (17), more particularly a protective coating layer (19) light-permeable to the luminescing colour in at least some areas and/or an adhesive layer (23), with an optionally previously applied reflective layer (24), is applied to the embossed, luminescent layer (3).
9. Method according to any one of claims 1 to 8, characterized in that the flexible Substrate (2) is removed from the security element (1, 101, 102).
10. Security element with a luminescent layer (3) and with a diffractive structure (6) produced by embossing the luminescent layer (3), which diffractive structure (6) co-operates with the luminescent layer (3) to visually appreciably alter the luminescence intensity as a function of the viewing angle (10) to the luminescent layer (3), characterized in that the luminescent layer (3) exhibits an embossed structure (20) penetrating the luminescent layer (3), which embossed structure (20) forms the diffractive structure (6).
11. Security element according to claim 10, characterized in that the luminescent layer (3) luminesces in at least two different colours.
12. Security element according to claim 10 or 11, characterized in that the luminescent layer (3) exhibits an, more particularly radiation-curable, preferably UV-crosslinking varnish (12) with a luminescent substance (13).
13. Security element according to any one of claims 10 to 12, characterized in that the security element (1, 101, 102) exhibits a covering layer (17), more particularly a protective coating layer (19) light-permeable to a luminescence colour in at least some areas and/or an adhesive layer (23), optionally on a reflective layer (24), which covering layer (17) covers the embossed layer (20).
14. Security element according to any one of claims 10 to 13, characterized in that the security element (1, 101, 102) exhibits a flexible substrate (2), on which the luminescent layer (3) is provided.
15. Value document, more particularly a bank note, travel pass, drivijng licence or personal identity card, having at least one security element (1, 101, 102) according to any one of claims 10 to 14.

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