CN116568520A

CN116568520A - Optically variable security element and method for producing an optically variable security element

Info

Publication number: CN116568520A
Application number: CN202180075682.0A
Authority: CN
Inventors: R·德梅尔; C·富塞; M·R·J·谢勒; K·H·谢勒; M·拉姆; T·萨特勒; M·海姆
Original assignee: Giesecke and Devrient GmbH
Current assignee: Giesecke and Devrient GmbH
Priority date: 2020-11-10
Filing date: 2021-11-03
Publication date: 2023-08-08
Also published as: EP4244071A1; DE102020006902A1; WO2022100883A1

Abstract

The invention relates to an optically variable security element, which has a layer sequence when viewed from the top. The layer sequence comprises a microstructure (2) providing a visual object visible from the upper side, the microstructure having a period of 2 μm to 50 μm and being achromatic. Furthermore, the layer sequence has a reflective layer (4) and a viewing-angle-dependent layer (6; 14) which are arranged on the microstructure (2), the reflective layer reflecting incident light, wherein the reflective layer (4) or the viewing-angle-dependent layer (6; 14) has at least one recess (15) and the other of the two layers is unstructured, wherein the layer having the recess (15) is located above the unstructured other layer, as viewed from the top. Instead of the recesses and the reflective layer, the security element can have an unstructured viewing-angle-dependent layer (6; 14) and an unstructured partially light-transmitting reflective layer (16; 18).

Description

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

The invention relates to an optically variable security element having a microstructure providing a visual object visible from the upper side, a reflective layer and a viewing angle dependent layer. The invention further relates to a method for producing or producing a corresponding optically variable security element.

An optically variable security element is known from EP 1506096 B1. By combining the achromatic surface structure with the film structure, the effect on rotation or tilting of the security element produces a defined color change.

A security element is likewise known from WO 01/03945A 1. The combination of the diffractive surface structure with the underlying layer having color-changing properties produces a visual effect in order to thereby increase the security against forgery of the security element.

An optically variable security element is also known from EP 2390106 A2. The optically variable effect is generated by a combination of a diffractive surface structure, which is coated with a thin metallization, with a thin film structure, such that it remains partially light transmissive.

The present invention is to provide an optically variable security element and a method for producing an optically variable security element, which has a layer sequence and a microstructure when viewed from the top side.

The invention is defined in the independent claims. Advantageous developments are specified in the dependent claims. The preferred embodiments are applicable to optically variable security elements and to methods for producing optically variable security elements.

An optically variable security element having a layer sequence and a microstructure is provided. The microstructure presents at least one visual object (or pattern) on the upper side of the optically variable security element. The microstructure is for example embossed into an embossing lacquer on the carrier substrate. The microstructure has structural elements which are arranged at regular intervals, i.e. periodically with a period of 2 μm to 50 μm. The individual structural elements themselves are unique and they do not have to all be identical. The term "periodically" relates only to an arrangement of structural elements at regular intervals.

The structural elements are designed in a unique manner, for example, in a unique manner inclined with respect to a main plane defined by the substantially planar design of the carrier substrate, such that the structural elements together represent at least one visual object. According to the present application, the periodic microstructure is, for example, also a saw tooth structure or a corrugated structure with a unique tooth slope, etc. when the microstructure is viewed in cross-section. By a period of 2 μm to 50 μm, the diffraction phenomenon affects the optical characteristics only little.

Each structural element serves, for example, as a pixel arranged on the surface of the carrier substrate. The pixels are arranged periodically. Each pixel forms, for example, an optically acting partial mirror and produces a unique optical effect by its orientation, so that a plurality of visual objects or visual object movements or visual object effects are presented by the microstructure in dependence on the tilt angle.

The microstructure is achromatic. The achromatic microstructure does not produce a color effect. They appear colorless to the observer. Thus, although a visual object is provided by the microstructure which is visible from above, in particular in relation to the tilt angle, the visual object is not polychromatic, since the achromatic nature of the microstructure is such that no color effect is present. Examples of achromatic microstructures are achromatic blazed structures, symmetrical microstructures (e.g. sinusoidal grids) or matte structures. As achromatic microstructures preferably blazed structures (e.g. sawtooth grids) and achromatic symmetrical microstructures (e.g. sinusoidal grids) are used.

In the method for producing optically variable security elements, the microstructure described is formed on a carrier substrate. This is preferably achieved by embossing, for example in an embossing lacquer.

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

The reflective layer may have at least one of the following layers: a metal layer, a coloured layer which gives a multicoloured visual sensory impression and a coloured/transparent resist.

The reflective layer cooperates with the microstructures such that the intensity of the incident light changes and thus the visual object produced by the microstructure effect can be seen well by the naked eye. Thus, the visual object is visible in the area of the security element where the reflective layer is present. The high refractive layer is a reflective layer.

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

Preferably, the viewing-angle dependent layer is designed as a color shifting layer system having a layer sequence of a partially light-transmitting reflector layer, a dielectric spacer layer and a reflector layer. Preferably, the viewing angle dependent layer has an optically variable ink that produces a viewing angle dependent color effect. Optically variable inks are preferably colourless substances which are mixed with optically variable pigments. The pigments have, for example, a symmetrical lamellar structure which, by means of interference effects, effects a viewing-angle-dependent color change, for example from green to blue or from magenta to green. The pigments are present, for example, in the form of platelets and their transverse dimensions are preferably in the range from 1 μm to 200 μm, particularly preferably in the range from 10 μm to 50 μm. The thickness of the platelets is preferably in the range from 200nm to 10. Mu.m, particularly preferably in the range from 350nm to 1500 nm.

The optically variable security element thus comprises a microstructure designed on/in the carrier substrate and the layer sequence described, which has a reflective layer and a viewing-angle dependent layer. The reflective layer and the viewing angle dependent layer can be designed in two variants.

In a first variant, both layers are located above the microstructure, and the layer located above, i.e. the reflective layer or the viewing-angle-dependent layer, has at least one recess. The other of the two layers is unstructured. In the layer sequence, the layer with the recesses is located, as viewed from the top, above another layer that is not structured. Unstructured means that this layer has no voids. However, this layer may be entirely embossed, i.e. with a structured surface.

The recess achieves that the optical effect of the lower layer can be seen in the recess and the optical effect of the upper layer can be seen outside the recess. Thereby, the void creates a second visual object.

If the upper layer is a viewing-angle dependent layer, the optically variable security element is perceived from above with a coloring that depends on the viewing angle. In the recess, only the reflective layer lying below in the layer sequence is active, so that, viewed from above, a visual object produced by the reflective layer is perceived in the recess, but no further viewing-angle-dependent color impression is perceived. Thus, the second visual object is a void in which there is no OVD color impression.

If the upper layer is a reflective layer, the visual object is visible from above; due to the hiding effect of the reflective layer, there is no OVD color impression. In contrast, in the space, the viewing-angle-related layer arranged lower functions, and thus in the space, a color impression depending on the viewing angle is perceived, but since there is no reflective layer, the visual object is not perceived. In this case, the color effect depending on the viewing angle appears only in the space.

In a method for producing an optical security element according to a first variant, a reflective layer is applied to a microstructure and a viewing-angle-dependent layer is applied to a carrier substrate or reflective layer, wherein at least one recess is provided in the reflective layer or the viewing-angle-dependent layer and the other of the two layers remains unstructured. The layer with the openings is located above another layer that is not structured, as viewed from the top. This makes manufacturing easier and contributes to the effect of security against counterfeiting.

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

The recesses in the reflective layer or viewing angle dependent layer can be produced in different ways, as will be explained below. Of course, a plurality of voids may be created.

In one alternative, the cleaning ink is printed onto the microstructure in the area where the void should be created in the layer prior to application of the layer. After the cleaning ink is applied to these areas, the layer is applied to the microstructure. The cleaning ink is then removed from the microstructure by contacting the cleaning ink with a medium (e.g., water) in which the cleaning ink is soluble, whereby in the areas where the microstructure is printed with the cleaning ink, the upper layer is also removed. Here, adjacent regions of the layer under which no cleaning ink is applied are unaffected.

In another alternative, after the layer has been applied to the microstructure, resist is applied regionally (in the areas where no voids need to be created) in order to open the voids into the layer. In a subsequent etching step, only the areas not covered by resist are etched, creating voids in the layer.

In another alternative, the voids in the layer are created by laser ablation. In this case, short light pulses with high intensity are guided in a grid-like manner over the surface of the reflective layer, so that the reflective layer is removed at the exposed locations and thus voids are formed in the reflective layer. Here, a short laser pulse with high intensity is scanned over an area in which a void needs to be provided. In the region covered by the laser pulse, the layer is removed and the layer underneath the layer becomes visible when viewed from the upper side.

In another alternative, the voids in the layer are created by transfer. The surface of the microstructure is treated or coated in such a way that the adhesion of the layer is impaired before the layer is applied. The film with good adhesion properties is then structured according to the voids that should be formed in such a way that the areas in which the voids are to be formed protrude in the axial direction from other areas and the protruding areas of the film are pressed directly onto the microstructure with the layer lying thereon. The structured film is then removed again and the layer is detached from the microstructure in the treated areas and remains attached to the structured film in the protruding areas, thus forming voids. In the case where the adhesion characteristics are opposite, the same effect is preferably achieved. This means that the metal is first applied to the structured film (which has axially protruding and lowered surface areas) and then transferred partly to the microstructure in such a way that the microstructure has better adhesion properties in the areas than the structured film. In a further alternative to the transfer, the region in which the recess should be provided is designed as a flat region, which protrudes in the axial direction beyond the adjacent structured region. Films with better adhesion properties can then be designed to be unstructured and metal removed only from the elevated flat areas of the microstructure. In the case of colored inks, the microstructures can also be printed directly out of the desired recesses.

If a void is created in the viewing angle dependent layer, this is preferably achieved by first coating the microstructure with a reflective layer and then partially overprinting the microstructure with optically variable ink. Thus, when viewed from the upper side, optically variable ink is perceived or seen in the region and the reflective layer applied on the microstructure is seen in the recess.

In embodiments, optically variable inks can also be applied over the entire surface at lower particle densities. The particle density is selected such that a proportion of the surface of the reflective layer is covered by the particles and the remaining surface remains uncovered. Surface coverage of 10-90%, preferably 30% -70%, can be achieved by diluting the ink or concentrating the pigment in the matrix accordingly. This also achieves the effect that both the areas of the optically variable ink and the areas of the reflective layer are visible when viewed from the upper side.

The region without the recess can be present in any shape, wherein the dimension of the region in at least one dimension is preferably between 5 μm and 200 μm, particularly preferably between 20 μm and 100 μm. The area coverage of the printed area is preferably in the range of 5% to 95%, particularly preferably in the range of 40% to 60%.

In a second variant of the optically variable security element, the reflective layer on the microstructure is designed as an unstructured layer, but is partially transparent on its surface, and the viewing-angle-dependent layer is located below the microstructure, as viewed from the top side. The viewing angle dependent layer is also unstructured. In a second variant, the incident light is not totally reflected by the reflective layer, but the reflective layer reflects part of the incident light and transmits part of the incident light. The reflective layer is partially light transmissive and unstructured with respect to this property. This variant does not require a structuring step at all and still shows good results, since the visual object has an OVD colour effect.

In a second variant of the method for producing optically variable security elements, an unstructured, partially light-transmitting reflective layer is applied to the microstructure and an unstructured viewing-angle-dependent layer is applied to the carrier substrate, for example by means of an adhesion step, so that the viewing-angle-dependent layer is axially underneath the microstructure coated with the reflective layer.

In a second variant, the microstructure is preferably coated over the entire surface with a partially light-transmitting reflective layer, which is composed of a transparent material having a high refractive index. The partially light transmissive reflective layer preferably has a refractive index greater than 2. An example of such a partially light transmissive reflective layer is a ZnS coating. The coating is preferably applied to the microstructure by vacuum evaporation. The thickness of the high refractive layer is preferably in the range of 1nm to 100nm, particularly preferably in the range of 10nm to 50 nm. Such partially light transmissive reflective layers reflect and transmit, respectively, a substantial portion of the incident light. Thereby, on the one hand, the optically variable effect of the microstructure coated with the partially light-transmitting reflective layer remains visible, thereby creating a visual object, and on the other hand, the viewing angle-dependent layer arranged below the microstructure creates an optical effect such that when the entire region is viewed from the upper side, the entire region is perceived as having a coloring that depends on the viewing angle. The viewing-angle-dependent layer can be designed here preferably as a color-shifting layer system, as already described; however, the viewing angle dependent layer may also be an optically variable ink.

In a further preferred embodiment of the second variant, the partially light-transmitting reflective layer can be a thin metal layer, the layer thickness of which is selected such that incident light is only partially reflected on this layer. The effect is then similar to that produced by a high refractive coating. The thin metal layer preferably has a layer thickness of 1nm to 30nm, particularly preferably a layer thickness of 1nm to 8 nm. The metal is preferably applied to the microstructure by vacuum evaporation.

Preferably, the partially light-transmitting layer can also be additionally structured. This can be achieved, for example, by the methods already described, namely laser ablation, application of cleaning ink, etching or the like. Whereby other visual objects may be produced.

As regards the recess referred to herein, it may also comprise a plurality of recesses which are not interconnected.

The invention is illustrated in more detail below by way of example with reference to the accompanying drawings. In the drawings:

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

fig. 2 shows an optically variable security element in a first variant when viewed from the top side;

fig. 3 shows an optically variable security element in a further embodiment in a first variant in a sectional view;

fig. 4 shows an optically variable security element in a further embodiment in a first variant when viewed from the top side;

fig. 5 and 6 show in section an optically variable security element in a second variant; and is also provided with

Fig. 7 shows an optically variable security element in a second variant when viewed from the top side.

Fig. 1 shows an optically variable security element in a sectional view. The microstructure 2 and the layer sequence can be seen. The microstructure 2 providing the visual object is on the carrier substrate 1, typically on the upper side of the carrier substrate. The microstructure 2 is for example applied in an embossing lacquer on the carrier substrate 1. The design of the microstructure 2 has already been described. The microstructure 2 is coated with a reflective layer 4 in regions which make visible the visual object provided by the microstructure 2, so that at least one recess 15 is provided in the coated region, in which recess the reflective layer 4 is either not coated on the microstructure 2 first or is subsequently removed. Other visual objects are created by the recess 15. The reflective layer 4 may preferably have at least one of the following layers: a metal layer, a colored layer that produces a multicolor visual sensory impression, a single color or a clear resist.

The viewing angle dependent layer is arranged below the carrier substrate 1, typically on its bottom side. The viewing-angle-dependent layer does not itself create a visual object, but imparts to the optically variable security element a color impression that is dependent on or dependent on the viewing angle of the observer. For example, the viewing angle dependent layer in fig. 1 is a color shifting layer system 6, which consists of a partially light transmissive reflector layer 8, a dielectric spacer layer 10 and a reflector layer 12. Alternatively, the viewing angle dependent layer may be an optically variable ink 14. The composition of optically variable ink 14 has been described.

Fig. 2 shows the optically variable security element shown in fig. 1 in a sectional view from the top. If the security element in fig. 1 is viewed from above, the reflective layer 4 can be seen in some areas and the recesses 15 with the color-shifting layer system 6 arranged below the reflective layer 4 can be seen in some other areas.

In the optically variable security element according to fig. 1 and 2, the microstructures 2 are formed on the carrier substrate 1. The microstructure is preferably embossed in an embossing lacquer on the carrier substrate 1 by an embossing process, for example. The microstructure 2 has a period of 2 μm to 50 μm and is achromatic. The structure of the microstructure 2 has already been described. The microstructure 2 provides at least one visual object but, due to its achromatic nature, appears colorless when viewed from the upper side. An example of an achromatic microstructure 2 has also been described. The blazed structure can be described regionally as a linear structure and can be identified in cross-section as a saw tooth profile (see fig. 1). Since the period of the microstructure 2 is 2 μm to 50 μm, the diffraction phenomenon only slightly affects the optical characteristics. Thus, the microstructure 2 acts like a tilting mirror; they do not produce a color effect. The visual object provided by the microstructure 2 is made visible by coating the microstructure 2 with a reflective layer 4.

The viewing angle dependent layer creates a color impression for the viewer that depends on the viewing angle. The provision of the recess 15 ensures that in the region where no recess 15 is provided, the visual object produced by the reflective layer 4 interacting with the microstructure 2 is visible when viewed from above and that a viewing-angle-dependent color impression is formed in the recess 15 by the viewing-angle-dependent layer. Thus creating a visual object from the recess 15. In general, rasterized views, such as halftone images, are possible in addition to microscopically rasterized voids, macroscopically voids. This recess 15 in the reflective layer 4 can be produced in different ways, as already explained. The possibilities for creating the recesses 15 are the application of a cleaning ink, the application of a resist in the areas where the recesses should not be opened, the creation of the recesses 15 by laser ablation or the transfer already described. A plurality of recesses 15 may also be produced, the shape of the recesses 15 being arbitrary here. The surface coverage of the void 15 is, for example, in the range of 10% to 90%, and particularly preferably in the range of 40% to 60%.

Fig. 3 shows a cross-sectional view of another embodiment of an optically variable security element. The microstructure 2 is applied to a carrier substrate 1 as in fig. 1. The microstructure 2 is now coated over its entire surface with a reflective layer 4, generally on its upper side. The reflective layer 4 is unstructured here. Optically variable ink 14 or other viewing angle dependent coating is located regionally on the reflective layer 4, thus forming a void 15. Fig. 4 shows the optically variable security element according to fig. 3 from above. The optically variable ink 14 can be seen here and the underlying reflective layer 4 can be seen in the recess 15.

In this embodiment, the reflective layer 4 is partially covered by optically variable ink 14. All usual printing methods are suitable here, but special care must be taken with regard to the accuracy of the registration. Preferably, optically variable ink 14 can also be printed on the entire face of reflective layer 4 and then structured by laser ablation. Here, a short laser pulse of high intensity is scanned across the face where it is desired to remove or modify optically variable ink 14, thereby forming void 15. The optically variable ink 14 is preferably also capable of being applied over the entire surface at a relatively low particle density. The particle density is here chosen such that a proportion of the faces of the particles are covered and the remaining faces remain uncovered (see above).

If a recess 15 is provided in the viewing-angle dependent layer, in the recess 15, the reflective layer 4 located below the viewing-angle dependent layer in the layer sequence becomes visible when viewed from above, which reflective layer is applied on the microstructure 2 and thereby produces a visual object. In the region where the void 15 is not provided, the viewing angle-dependent layer produces a color impression depending on the viewing angle. In this case, therefore, the recess 15 also creates a visual object.

Fig. 5 and 6 show a second variant of an optically variable security element. As in the first variant, in the embodiment of fig. 5, the microstructures 2 are applied to the carrier substrate 1. The high refractive layer 16 is applied as a partially light-transmitting reflective layer on the microstructure 2, typically as an unstructured layer on the upper side of the microstructure. The partially light-transmitting reflective layer reflects and transmits a portion of incident light. In the embodiment of fig. 6, a partially light-transmitting reflective layer is likewise provided, 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 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 shifting layer system 6.

Fig. 7 shows a second variant of an optically variable security element, viewed from the top, with the structure according to fig. 5 and 6. In the region 20, both the optical effect (creating a visual object) caused by the combination of the partially light-transmitting reflective layer and the microstructure 2 and the viewing-angle dependent color effect caused by the viewing-angle dependent layer can be seen. In this variant, no recess 15 is provided in either the partially light-transmitting reflective layer or in the viewing-angle-dependent layer. Both layers are unstructured.

In the embodiment according to fig. 5 and 7, the microstructure 2 is coated over the whole area with a translucent material having a high refractive index, whereby a partially light-transmitting reflective layer is formed. Such high refractive coatings 16 reflect and transmit, respectively, a substantial portion of the incident light. Thereby, on the one hand, the optically variable effect of the microstructure 2 coated with the high refractive coating 16 remains visible (creating a visual object), and on the other hand, the optically variable ink 14 arranged underneath ensures that the entire area is perceived by the observer with a coloring that depends on the viewing angle. The high refractive coating 16 preferably has a refractive index greater than 2. An example of a high refractive coating 16 is a ZnS coating. The material is preferably applied to the microstructure 2 by vacuum evaporation. The thickness of the high refractive layer 16 may be in the range of 1nm to 100nm, and particularly preferably in the range of 10nm to 50 nm. Alternatively, the high refractive layer may be additionally structured. This can be achieved by laser ablation, application of cleaning ink or etching methods as already described.

In a preferred embodiment, according to fig. 6 and 7, a thin metal layer 18 is applied to the upper side of the microstructure 2. This gives almost the same effect as a coating of the microstructure 2 with a high refractive coating 16. The layer thickness is chosen to be very thin so that the incident light is only partially reflected on the thin metal layer 18, whereby the visual object can still be recognized by the microstructure 2 coated with the reflective layer 4. Thus, part of the incident light is reflected and part of the incident light is transmitted, so that the color shifting layer system 6 arranged below the carrier substrate 1 enables the entire area 20 to be perceived with a viewing angle dependent coloration when viewed from the upper side. Instead of the color shifting 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 1nm to 30nm, particularly preferably a layer thickness of 1nm to 8 nm. The thin metal layer 18 is preferably applied to the microstructure 2 by vacuum evaporation.

List of reference numerals

1 Carrier substrate

2 microstructure

4 reflective layer

6 color shifting layer system

8 partially light transmissive reflector layer

10 dielectric spacer layer

12 reflector layer

14 optically variable ink

15 empty part

16 high refractive layer

18 thin metal layer

20 area

Claims

1. An optically variable security element, the security element having

Providing a microstructure (2) of a visual object visible from the upper side,

a reflective layer (4) and a viewing-angle dependent layer (6; 14) arranged on the microstructure (2), said reflective layer reflecting incident light,

it is characterized in that the method comprises the steps of,

-the microstructure (2) has a period of 2 to 50 μm and is achromatic, and

-the reflective layer (4) or the viewing-angle dependent layer (6; 14) has at least one void (15) and the other of the two layers is unstructured, wherein the layer with the void (15) is located above the unstructured other layer as seen from the upper side.

2. An optically variable security element, the security element having

Providing a microstructure (2) of a visual object visible from the upper side,

-an unstructured, partially light-transmitting reflective layer (16; 18) arranged on the microstructure (2), and

an unstructured viewing-angle dependent layer (6; 14), wherein the viewing-angle dependent layer (6; 14) is located below the microstructure (2) as seen from the upper side,

it is characterized in that the method comprises the steps of,

-the microstructure (2) has a period of 2 to 50 μm and is achromatic.

3. Optically variable security element according to claim 2, characterized in that the partially light-transmitting reflective layer is a high refractive layer (16).

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

5. Optically variable security element according to one of the preceding claims, characterized in that the viewing-angle-dependent layer (6; 14) is a color-shifting 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, wherein,

applying microstructures (2) providing visual objects visible from the upper side onto/into a carrier substrate (1),

-applying a reflective layer (4) on the microstructure (2), said reflective layer reflecting the incident light, and

-applying a viewing-angle dependent layer (6; 14) to the carrier substrate or the reflective layer (4), characterized in that,

-the microstructure (2) has a period of 2 to 50 μm and is achromatic, and

-providing at least one recess (15) in the reflective layer (4) or the viewing-angle dependent layer (6; 14) and the other of the two layers remains unstructured, wherein the layer provided with the recess (15) is located above the unstructured other layer as seen from the top side.

8. A method for producing an optically variable security element, wherein,

-applying an unstructured, partially light-transmitting reflective layer (16; 18) onto the microstructure (2), and

applying an unstructured viewing-angle dependent layer (6; 14) onto the carrier substrate (1), wherein the viewing-angle dependent layer (6; 14) is located under the microstructure (2) as seen from the upper side,

it is characterized in that the method comprises the steps of,

-the microstructure (2) has a period of 2 to 50 μm and is achromatic.

9. A method for manufacturing an optically variable security element according to claim 8, wherein the partially light transmissive reflective layer is a high refractive layer (16).

10. A method for manufacturing an optically variable security element according to claim 8, wherein the partially light transmissive reflective layer is a thin metal layer (18).

11. Method for producing an optically variable security element according to one of claims 7 to 10, characterized in that the viewing-angle-dependent layer is a color-shifting 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).