EP4244071A1

EP4244071A1 - Optically variable security element and method for producing an optically variable security element

Info

Publication number: EP4244071A1
Application number: EP21805837.8A
Authority: EP
Inventors: Raphael DEHMEL; Christian Fuhse; Maik Rudolf Johann SCHERER; Kai Herrmann SCHERER; Michael Rahm; Tobias Sattler; Manfred Heim
Original assignee: Giesecke and Devrient Currency Technology GmbH
Current assignee: Giesecke and Devrient Currency Technology GmbH
Priority date: 2020-11-10
Filing date: 2021-11-03
Publication date: 2023-09-20
Anticipated expiration: 2041-11-03
Also published as: CN116568520A; DE102020006902A1; WO2022100883A1; EP4244071B1

Abstract

The invention relates to an optically variable security element which, viewed from the top, has a layer sequence. The layer sequence contains a micro-structure (2) which provides a motif that is visible from the top, and which micro-structure has a period of 2 μm to 50 μm and is achromatic. Furthermore, the layer sequence has a reflective layer (4) that is arranged on the micro-structure (2) and reflects incident light, and has a viewing-angle-dependent layer (6; 14). The reflective layer (4) or the viewing-angle-dependent layer (6; 14) has at least one recess (15), and the other one of the two is unstructured. That layer that has the recess (15) lies on top of the other layer, which is unstructured, as viewed from the top. Instead of the recess and the reflective layer, the security element can have an unstructured, viewing-angle-dependent layer (6; 14) and an unstructured, semi-reflective reflective layer (16; 18).

Description

O p ti c v a r i a b l e s e l e m e n t a n d p r o c e r t i n g s o m p r e c u t i o n a s o p ti c v a r i a b l e s e l e m e t

The invention relates to an optically variable security element that has a microstructure that provides a motif that is visible from the top, a reflection layer, and a layer that is dependent on the viewing angle. The invention further relates to a method for producing a corresponding optically variable security element.

An optically variable security element is known from EP 1506096 B1. The combination of achromatic surface structures with a thin-film structure causes a defined color change when the security element is rotated or tilted.

A security element is also known from WO 01/03945 A1. The combination of diffractive surface structures with an underlying layer with color-changing properties creates a visual effect in order to increase the counterfeit security of the security element.

An optically variable security element is also known from EP 2390106 A2. Optically variable effects are generated by combining diffractive surface structures, which are coated with a thin metallization so that they remain partially transparent, with a thin film structure.

It is intended to provide an optically variable security element and a method for producing the optically variable security element which, when viewed having a layer sequence and a microstructure from an upper side.

The invention is defined in the independent claims. Advantageous developments are specified in the dependent claims. The preferred developments apply to the optically variable security element and the method for producing the optically variable security element.

An optically variable security element, which has a layer sequence and a microstructure, is provided. The microstructure presents at least one motif on the upper side of the optically variable security element. It is embossed, for example, in an embossing lacquer on a carrier substrate. The microstructure has structural elements that are arranged at regular intervals, ie periodically, with a period of 2 pm to 50 pm. The individual structural elements themselves are individual, they do not all have to be the same. The term "periodic" only refers to the arrangement of the structural elements at regular intervals.

The structural elements are individually designed such. B. compared to a fixed by the substantially planar configuration of the carrier substrate, individually inclined main plane that together they present at least one motif. Periodic microstructures within the meaning of the application are also, for example, a sawtooth structure with individual tooth inclination, a wave structure or the like when considering the microstructure in the sectional view. Due to the period of 2 gm to 50 gm, diffraction phenomena have only a slight influence on the optical properties. Each structural element acts z. B. as a pixel, which is arranged on the surface of the carrier substrate. The pixels are arranged according to the period. Each pixel forms z. B. an optically effective facet and generates an individual optical effect through its orientation, so that depending on the tilt angle several motifs or motif movements or motif effects are presented by the microstructure.

The microstructure is achromatic. Achromatic microstructures do not produce a color effect. They appear colorless to the viewer. Although the microstructure provides a motif that is visible from above and is in particular dependent on the tilt angle, the motif is not multicolored due to the lack of a color effect resulting from the achromatic property of the microstructure. Examples of achromatic microstructures are achromatic blaze structures, symmetrical microstructures (such as sine gratings) or matt structures. Blaze structures (such as, for example, sawtooth gratings) and achromatic symmetrical microstructures (such as, for example, sinusoidal gratings) are preferably used as achromatic microstructures.

In the method for producing the optically variable security element, the described microstructure is formed on the carrier substrate. This is preferably done by embossing, e.g. B. in an embossing lacquer realized.

The layer sequence of the optically variable security element has a reflection layer and a viewing-angle-dependent layer.

The reflective layer may include at least one of the following layers: a metal layer, a chromatic paint layer that produces a multicolored visual sensation, and a colored/transparent etching resist. In cooperation with the microstructure, the reflective layer ensures that the intensity of the incident light changes, making the motif created by the microstructure clearly visible to the naked eye. The motif is thus visible in areas of the security element in which the reflective layer is present. A high refractive index layer is a reflective layer.

The viewing angle dependent layer creates a viewing angle dependent (so-called OVD) color impression. The color of the area of the optically variable security element in which the viewing-angle-dependent layer is visible changes depending on the direction of illumination or viewing.

The layer that is dependent on the viewing angle is preferably designed as a color shift layer system with a layer sequence made up of a partially transparent reflector layer, a dielectric spacer layer and a reflector layer. The viewing-angle-dependent layer can preferably have an optically variable ink that produces a viewing-angle-dependent color effect. The optically variable ink is a preferably colorless substance interspersed with optically variable pigments. The pigments have a z. B. symmetrical thin-film structure, which achieves a viewing angle-dependent color change, such as from green to blue or from magenta to green, through interference effects. The pigments are z. B. in platelet form and their lateral dimensions are preferably in a range from 1 gm to 200 μm, particularly preferably in a range from 10 gm to 50 μm. The thicknesses of the platelets are preferably in a range from 200 nm to 10 μm, particularly preferably in a range from 350 nm to 1500 nm.

The optically variable security element thus includes the microstructure, which is formed on/in the carrier substrate, and the explained layer follow with the reflective layer and the viewing angle dependent layer. The reflection layer and the viewing-angle-dependent layer can be designed in two variants.

In a first variant, both layers overly the microstructure and top layer, i. H. the reflective layer or the viewing-angle-dependent layer has at least one gap. The other of the two layers is unstructured. In the layer sequence, that layer which has the cutout, seen from the top, lies above the other layer which is unstructured. Restructured means that this layer has no recess. But it can definitely be embossed, i. H. have a textured surface.

The recess ensures that the optical effect of the lower layer is visible in the recess and the optical effect of the upper layer is visible outside of the recess. As a result, the recess creates a second motif.

If the upper layer is the viewing-angle-dependent layer, the optically variable security element is perceived from above with a viewing-angle-dependent coloring. Only the reflective layer at the bottom of the layer sequence is effective in the gap, so that the motif created by the reflective layer can be seen in the gap when viewed from above, but without the color impression otherwise present, which depends on the viewing angle. The second motif is therefore the recess in which the OVD color impression is missing.

If the top layer is the reflective layer, the motif is visible when viewed from above; but without an OVD color impression due to the covering effect of the reflection layer. In the recess, on the other hand, the deeper one acts layer that depends on the viewing angle, so that a color impression that depends on the viewing angle is perceived in the recess - but no motif because there is no reflective layer there. In this case, the viewing angle-dependent color effect only occurs in the recess.

In the method according to the first variant for producing the optical security element, the reflective layer is applied to the microstructure and the viewing angle-dependent layer to the carrier substrate or the reflective layer, with the at least one recess being introduced into the reflective layer or the viewing angle-dependent layer and the other of the two layers being unstructured will be left. In this case, that layer in which the cutout was introduced is arranged above the other layer, which is unstructured, as seen from the top. This simplifies production and promotes a forgery-proof effect.

If the gap is provided in the reflection layer or the viewing-angle-dependent layer in the first variant, the area coverage of the gap should preferably be between 10% and 90%, particularly preferably between 30% and 70%.

The gap in the reflection layer or the viewing-angle-dependent layer can be produced in different ways, which are explained below. Of course, several recesses can also be created.

In one option, prior to applying the layer, a wash ink is printed onto the microstructure in the areas where the cavity in the layer is to be created. The layer is only applied to the microstructure after the wash color has been applied to these areas. connecting Subsequently, the wash ink is removed from the microstructure by contacting it with the medium in which it is soluble (e.g. water), thereby also removing the overlying layer in the areas where the microstructure has been printed with the wash ink will. Adjacent areas of the layer where no wash color has been applied under the layer will not be affected.

In another option, an etching resist is applied in regions (in the areas in which no recesses are intended) to make the recesses in the layer after the layer has been applied to the microstructure. In a subsequent etching step, only the areas not covered with the etch resist are etched, thereby creating gaps in the layer.

In a further option, the gaps in the layer are produced by laser ablation. In this case, short light pulses with high intensity are guided in a raster-like manner on the surface of the reflective layer, so that the reflective layer is removed at the exposed points and the gaps in the reflective layer are thus produced. A short, high-intensity laser pulse scans the areas in which the recesses are to be provided. In the areas covered by the laser pulses, the layer is removed and the underlying layer becomes visible when viewed from the top.

In a further option, the gaps in the layer are created by a transfer. In this case, the surface of the microstructure is treated or coated before the layer is applied in such a way that the adhesion of the layer is impaired. A film with good adhesion properties is then structured according to the recesses that are to be created. ted by the area in which the recess is to be formed axially protruding beyond the other areas and the raised areas of the film are pressed directly against the microstructure with the layer located on top. The structured film is then removed again and the layer detaches from the microstructure in the treated areas and sticks to the structured film in the raised area, creating the gap. The same effect can be preferably obtained when the adhesion properties are reversed. This means that the metal is first applied to the structured foil (with axially raised and lowered surface areas) and then partially transferred to the microstructure, in that the microstructure has better adhesion properties in areas than the structured foil. In a further alternative of the transfer, the areas in which the recesses are to be provided are designed as flat areas which protrude axially beyond the adjacent structured areas. Then the foil can be made unstructured with the better adhesion properties and the metal is only removed from the raised flat areas of the microstructure. In the case of a chromatic color, this can also be printed directly with the desired recess.

If the gap is produced in the viewing-angle-dependent layer, this is preferably achieved in that the microstructure is first coated with the reflection layer and this is then partially overprinted with the optically variable ink. Consequently, when viewed from the top, one perceives the optically variable ink in areas and the reflection layer applied to the microstructure in the recess. In embodiments, the optically variable ink can also be applied over the entire surface with a low particle density. The particle density is selected in such a way that a certain percentage of the area of the reflection layer is covered by particles and the remaining area remains uncovered. A surface coverage of 10-90%, preferably 30%-70%, is achieved by appropriate dilution of the ink or concentration of pigments in a matrix. This also achieves the effect that both areas of the optically variable ink and areas of the reflection layer are visible when viewed from the top.

The areas without a gap can be in any form, with their dimensions in at least one dimension preferably being between 5 μm and 200 μm, particularly preferably between 20 μm and 100 μm. The area coverage of the printed areas is preferably in a value range from 5% to 95 %, particularly preferably from 40% to 60%.

In a second variant of the optically variable security element, the reflective layer on the microstructure is formed as an unstructured layer that is partially transparent over its surface, and the viewing-angle-dependent layer lies below the microstructure, viewed from the top. It is also unstructured. In the second variant, incident light is not purely reflected by the reflection layer, rather the reflection layer reflects parts of the incident light and transmits parts of the incident light. It is partially permeable and not structured with regard to this property. This variant manages without any structuring step and still shows a good effect, since the motif has an OVD color effect. In the method of the second variant for producing the optically variable security element, the unstructured, partially transparent reflection layer is applied to the microstructure and the unstructured, viewing angle-dependent layer is applied to the carrier substrate, for example by an adhesive step, so that it is located axially below the microstructure coated with the reflection layer .

In the second variant, the microstructure is preferably coated all over with the partially transparent reflection layer, consisting of a transparent material that has a high refractive index. The partially transparent reflection layer preferably has a refractive index greater than two. An example of such a partially transparent reflection layer is a ZnS coating. The coating is preferably applied to the microstructure by vacuum vapor deposition. The thickness of the high-index layer can preferably be in a range from 1 nm to 100 nm, particularly preferably in a range from 10 nm to 50 nm. Such a partially transparent reflection layer reflects and transmits significant portions of the incident light. As a result, on the one hand, the optically variable effect of the microstructure coated with the partially transparent reflection layer remains visible, so that a motif is created, and on the other hand, the viewing-angle-dependent layer arranged underneath the microstructure creates the optical effect that the entire area, when viewed from the top, is perceived with a coloration dependent on the viewing angle. The layer that is dependent on the viewing angle can preferably be implemented as a color shift layer system, as has already been described; however, it can also be an optically variable ink.

In a further preferred embodiment of the second variant, the partially transparent reflection layer can be a thin metal act layer whose layer thickness is chosen so that incident light is only partially reflected on the layer. The effect is then comparable to the effect caused by the high-index coating. The thin metal layer preferably has a layer thickness of 1 nm to 30 nm, particularly preferably a layer thickness of 1 nm to 8 nm. The metal is preferably applied to the microstructure by vacuum vapor deposition.

The partially transparent layer can preferably also be additionally structured. This can be achieved, for example, by the methods already described of laser ablation, application of a wash color, etching, or the like. This allows additional motifs to be created.

As far as a recess is mentioned here, it can also include several recesses that are not connected to one another.

The invention is explained in more detail below by way of example with reference to the drawing. In the drawing shows:

1 shows an optically variable security element in a first variant in a sectional view;

2 shows the optically variable security element in the first variant when viewed from an upper side;

3 shows the optically variable security element in the first variant in a further embodiment in a sectional view; 4 shows the optically variable security element in the first variant in the further embodiment when viewed from the top;

5 and 6 an optically variable security element in a second variant in a sectional view, and

7 shows the optically variable security element in the second variant when viewed from the top.

1 shows an optically variable security element in a sectional view. A microstructure 2 and a layer sequence can be seen. The microstructure 2, which provides a motif, is located on a carrier substrate 1, generally on its upper side. The microstructure 2 is applied to the carrier substrate 1 in an embossing lacquer, for example. The configuration of the microstructure 2 has already been described. The microstructure 2 is partially coated with a reflection layer 4, which makes the motif provided by the microstructure 2 visible, so that at least one recess 15 is provided in the coated area, where the reflection layer 4 is not applied to the microstructure 2 in the first place or is subsequently removed became. Through the recess 15 another motif is created. The reflection layer 4 can preferably have at least one of the following layers: a metal layer, a colored layer that produces a multicolored visual sensory impression, monochromatic or transparent etching resist.

A viewing angle-dependent layer is arranged underneath the carrier substrate 1, generally on its underside. The viewing angle-dependent layer does not create a motif per se, but gives the optically variable security element ment a color impression that depends on the viewing angle of a viewer. The viewing angle dependent layer in FIG. B. a color shift layer system 6, which is composed of a partially transparent reflector layer 8, a dielectric spacer layer 10 and a reflector layer 12 is constructed. Alternatively, the viewing angle dependent layer can be an optically variable ink 14 . The composition of the optically variable ink 14 has already been explained.

FIG. 2 shows the optically variable security element shown in section in FIG. 1 seen from an upper side. If the security element in FIG. 1 is viewed from above, the reflective layer 4 can be seen in areas and the gap 15 with the color shift layer system 6 arranged under the reflective layer 4 can be seen in other areas.

In the case of the optically variable security element according to FIGS. 1 and 2, the microstructure 2 is formed on the carrier substrate 1. FIG. This is preferably embossed on the carrier substrate 1 by an embossing process, for example in an embossing lacquer. The microstructure 2 has a period of 2 μm to 50 μm and is achromatic. The structure of the microstructure 2 has already been explained. The microstructure 2 provides at least one motif, but appears colorless when viewed from above due to its achromatic property. Examples of achromatic microstructures 2 have also already been explained. Blaze structures can be described as linear structures in some areas and can be seen as a sawtooth profile (FIG. 1) in the sectional view. Due to the period of the microstructure 2 of 2 gm to 50 gm, diffraction phenomena only slightly affect the optical properties. As a result, the microstructures 2 act like tilted mirrors; they produce no color effect. By coating the Microstructure 2 with the reflection layer 4 makes the motif provided by the microstructure 2 visible.

The layer that depends on the viewing angle produces a color impression on the viewer that depends on the viewing angle. The provision of the recess 15 ensures that in areas where no recess 15 is provided, the motif generated by the reflection layer 4 in interaction with the microstructure 2 is visible when viewed from above and a color impression dependent on the viewing angle is produced in the recess 15 by the viewing angle dependent layer. A motif is thus generated from the cutout 15 . In general, in addition to microscopically screened gaps and macroscopic gaps, screened representations such as halftone images are also possible. This recess 15 in the reflection layer 4 can be produced in different ways, as has already been explained. Possibilities for producing the cutout 15 are the application of a wash color, the application of an etching resist in areas that are not to be cut out, the creation of the cutout 15 by laser ablation, or an already described transfer. It is also possible to create several recesses 15, the shapes of the recess 15 being arbitrary. The area coverage of the recess 15 is z. B. in a range from 10% to 90%, more preferably from 40% to 60%.

FIG. 3 shows a further embodiment of the optically variable security element in a sectional view. As in FIG. 1, the microstructure 2 is applied to the carrier substrate 1 . This microstructure 2 is now coated with the reflection layer 4 over its entire surface, usually on its upper side. In this case, the reflection layer 4 is unstructured. Areas of the optically variable ink 14 or 14 are located on the reflective layer 4 another viewing angle-dependent coating, so that the recess 15 is formed. FIG. 4 shows the optically variable security element according to FIG. 3 viewed from above. The optically variable ink 14 and the recess 15, the underlying reflection layer 4 can be seen.

In this embodiment, the reflection layer 4 is partially overprinted with the optically variable ink 14 . All common printing processes are suitable, but particular attention must be paid to register accuracy. Preferably, the optically variable ink 14 can also be printed over the entire area of the reflection layer 4 and then structured by laser ablation. In this case, short laser pulses with high intensity scan across the areas from which the optically variable ink 14 is to be removed or modified, so that the gap 15 is formed. The optically variable ink 14 can preferably also be applied over the entire surface with a low particle density. The particle density is chosen so that a certain percentage of the surface is covered by particles and the remaining surface remains uncovered (see above).

If the recess 15 is provided in the viewing angle-dependent layer, the reflection layer 4 located in the layer sequence below the viewing angle-dependent layer is visible in the recess 15 when viewed from above, which is applied to the microstructure 2 and thus creates a motif. In the areas in which no gap 15 is provided, the viewing-angle-dependent layer produces a viewing-angle-dependent color impression. In this way, the recess 15 also creates a motif.

FIGS. 5 and 6 show a second variant of the optically variable security element. As in the first variant is in the embodiment in Fig. 5 the microstructure 2 is applied to the carrier substrate 1 . A highly refractive layer 16 is applied to this microstructure 2 as a partially transparent reflection layer, usually on its upper side as an unstructured layer. The partially transparent reflection layer reflects and transmits parts of the incident light. A partially transparent reflection layer is also provided in the embodiment of FIG. 6, in this case in the form of a thin, unstructured metal layer 18. The viewing-angle-dependent layer is arranged on the underside of the carrier substrate 1. In the exemplary embodiment of FIG. 5, the viewing angle-dependent layer is designed as an optically variable ink 14. In the case of FIG. 6, the viewing angle-dependent layer is designed as a color shift layer system 6. FIG.

FIG. 7 shows the second variant of the optically variable security element, with a structure according to FIGS. 5 and 6, seen from the top. In area 20, both the optical effects caused by the partially transparent reflection layer in connection with the microstructure 2 (a motif is produced) and color effects that are dependent on the viewing angle and are caused by the layer that is dependent on the viewing angle can be seen. In this variant, no gaps 15 are provided either in the partially transparent reflection layer or in the layer that is dependent on the viewing angle. Both layers are unstructured.

In the embodiment according to FIGS. 5 and 7, the microstructure 2 is coated over its entire surface with a semi-transparent material that has a high refractive index, so that a partially transparent reflection layer is formed. Such a high-index coating 16 reflects and transmits significant portions of the incident light. As a result, on the one hand, the optically variable effect of the microstructure 2 coated with the high-index layer 16 remains visible (a motif is produced), and on the other On the other hand, the optically variable ink 14 arranged below ensures that the entire area is perceived by an observer with a coloration dependent on the viewing angle. The high refractive index coating 16 preferably has an index of refraction that is greater than two. An example of the high-index coating 16 is a ZnS coating. The material is preferably applied to the microstructure 2 by vacuum vapor deposition. The thickness of the high-index layer 16 can be in a range from 1 nm to 100 nm, particularly preferably from 10 nm to 50 nm. Alternatively, the high-index layer can also be additionally structured. This can be achieved by the methods of laser ablation, application of wash color or etching already described.

In a preferred embodiment, a thin metal layer 18 is applied to the upper side of the microstructure 2 according to FIGS. This produces almost the same effect as coating the microstructure 2 with the high-index coating 16. The layer thickness is chosen so thin that incident light is only partially reflected on the thin metal layer 18, which means that the motif can still be seen through the microstructure 2 coated with the reflective layer 4 is recognizable. Portions of the incident light are therefore reflected and portions of the incident light are transmitted, so that the color shift layer system 6 arranged below the carrier substrate 1 allows the entire region 20 to be perceived with a coloring dependent on the viewing angle when viewed from the top. Instead of the color shift layer system 6, the optically variable ink 14 can preferably also be arranged below the microstructure 2. The thin metal layer 18 should preferably have a layer thickness of 1 nm to 30 nm, particularly preferably 1 nm to 8 nm. The thin metal layer 18 is preferably deposited on the micro- Structure 2 applied.

LIST OF REFERENCE NUMBERS 1 Support substrate

2 micro structure

4 reflective layer

6 Colourshift layer system

8 partially transparent reflector layer 10 dielectric spacer layer

12 reflector layer

14 optically variable ink

15 recess

16 high index layer 18 thin metal layer

20 area

Claims

P atentClaims

1. Optically variable security element, which has a microstructure (2) providing a motif visible from the top, a reflective layer (4) arranged over the microstructure (2), which reflects incident light, and a viewing-angle-dependent layer (6; 14), thereby characterized in that the microstructure (2) has a period of 2 gm to 50 |im and is achromatic and the reflection layer (4) or the viewing angle-dependent layer (6; 14) has at least one recess (15) and the other of the two is unstructured , wherein that layer which has the recess (15) lies above the other layer, which is unstructured, as seen from the top.

2. Optically variable security element, which has a microstructure (2) providing a motif visible from the top, an unstructured, partially transparent reflection layer (16; 18) arranged over the microstructure (2), and an unstructured, viewing-angle-dependent layer (6; 14 ), wherein the viewing-angle-dependent layer (6; 14) lies below the microstructure (2) as seen from the top, characterized in that the microstructure (2) has a period of 2 gm to 50 |im and is achromatic.

3. Optically variable security element according to claim 2, characterized in that the partially transparent reflection layer is a highly refractive layer (16).

4. Optically variable security element according to claim 2, characterized in that the partially transparent reflection layer is a thin metal layer (18).

5. Optically variable security element according to one of the above claims, characterized in that the viewing angle dependent layer (6; 14) has a color shift layer system (6).

6. Optically variable security element according to one of claims 1 to 4, characterized in that the viewing angle-dependent layer has an optically variable ink (14).

7. A method for producing an optically variable security element, in which a microstructure (2) providing a motif visible from the top is applied to/in a carrier substrate (1), a reflective layer (4), which reflects incident light, over the microstructure (2 ) is applied, and a viewing angle-dependent layer (6; 14) is applied to the carrier substrate or the reflection layer (4), characterized in that the microstructure (2) has a period of 2 gm to 50 gm and is achromatic, and in which Reflective layer (4) or the viewing angle dependent layer (6;

14) at least one recess (15) is introduced and the other of the two layers is left unstructured, with that layer in which the recess (15) was introduced, seen from the top, lies over the other layer, which is unstructured.

8. Method for producing an optically variable security element, wherein a microstructure (2) providing a motif visible from the top is applied to/into a carrier substrate (1), an unstructured, partially transparent reflection layer (16; 18) is applied to the microstructure (2) is applied, and an unstructured, viewing-angle-dependent layer (6; 14) is applied to the carrier substrate (1), the viewing-angle-dependent layer (6; 14) lying under the microstructure (2) as seen from the top, characterized in that the Microstructure (2) has a period of 2 gm to 50 gm and is achromatic.

9. Method for producing an optically variable security element according to claim 8, characterized in that the partially transparent reflection layer is a high-index layer (16).

10. Method for producing an optically variable security element according to claim 8, characterized in that the partially transparent reflection layer is a thin metal layer (18).

11. A method for producing an optically variable security element according to any one of claims 7 to 10, characterized in that the viewing angle-dependent layer has a color shift layer system (6).

12. Method for producing an optically variable security element according to one of claims 7 to 10, characterized in that the viewing angle-dependent layer (6; 14) has an optically variable ink (14).