WO2019063121A1

WO2019063121A1 - Method for producing an optically variable element, and corresponding element

Info

Publication number: WO2019063121A1
Application number: PCT/EP2018/000447
Authority: WO
Inventors: Martin Imhof
Original assignee: Giesecke+Devrient Currency Technology Gmbh
Priority date: 2017-09-28
Filing date: 2018-09-24
Publication date: 2019-04-04
Also published as: EP3687826A1; EP3687826B1; DE102017009092A1

Abstract

The invention relates to a method for producing an optically variable element, the method comprising the following steps: creating a relief structure formed from a plurality of relief elements (11, 12) lying side by side in a plane, wherein the relief elements have a relief form that is non-parallel to the plane; and selectively modifying the relief structure, wherein the modification and the relief form of the relief elements are matched in such a way that for the viewer, the modified relief structure shows different representations depending on the viewing angle. The relief structure is created by means of an additive method, wherein multiple sub-steps of the additive method are executed for each relief element (11, 12), and the sub-steps for the relief element (11, 12) determine the relief form of the relief element.

Description

Process for producing an optically variable element

as well as corresponding element

The invention relates to a method for producing an optically variable element and to a corresponding element.

Data carriers, such as security documents or ID documents, but also other valuables, such as branded goods, are often provided with elements for the purpose of security, which permit verification of the authenticity of the data carrier and at the same time serve as protection against unauthorized reproduction. Optically variable elements show different representations to a viewer depending on the viewing angle. In particular with the aid of an embossed structure and a contrasting coating, such optically variable elements can be produced. The embossed structure and the coating are coordinated so that different subjects become visible (or not visible) to the observer under different viewing angles or a motif moves. For example, WO 02/20280 A1, WO 2006/018232 A1 or DE 10 2014 012207 A1 show coated embossed structures with motif change.

The invention has for its object to provide a flexible but cost-effective production method for optically variable elements, which in particular also allows to create optically variable elements on the target substrate. This object is solved by the features of the independent claims. Further developments of the invention are the subject of the dependent claims.

A basic idea of the present solution is to additively produce the relief elements of a relief structure, which are conventionally produced by embossing, by means of printing in several sub-steps. In particular, in special cases, for example, if only small numbers of optically variable elements on the basis of the same relief structure are created or for novel relief structures, for example, with negative relief flanks, the approach turns out to be advantageous.

In a method for producing an optically variable element, a relief structure is created and the created relief structure selectively modified, for example, colored. The relief structure comprises a multiplicity of relief elements which lie next to one another in a plane and have a relief shape which is not parallel to the plane. The created relief structure is selectively modified. The modification and the relief shape of the relief elements are coordinated with one another such that for a viewer the modified relief structure shows different representations depending on the viewing angle. In the present case, the relief structure is at least partially created by means of an additive method, wherein for relief elements in each case a plurality of sub-steps of the additive method are carried out and the sub-steps, the relief shape of the relief element is determined.

In their relief form, the relief elements may, for example, be pimples, cones, pyramids (with a quadrangular or polygonal floor plan), truncated pyramids (with a four- or n-square layout), truncated cone, round nubb or gelabschnitt be formed. Further, the relief elements may have a directional surface as a relief shape. The relief element with a directed surface (surface element) may be, for example, a round or n-shaped, preferably quadrangular or hexagonal, surface. In the relief structure, the surface elements are preferably arranged adjacent to one another and / or gap-filling. The surface can be described by its orientation and its inclination (to the plane of the relief structure) and optionally by its height in relief. The relief element can be designed as a relief line, for example roof-shaped with two flanks or with a round cross-section. The relief elements are preferably arranged side by side in a (one or) two-dimensional relief grid. The relief elements can be arranged in the relief frame at a distance or without spacing. The relief elements with the relief shape (which is not parallel to the plane of the relief elements) have locally different heights. Due to the additive substeps, the relief element becomes locally different

Heights generated. The height profile of the relief elements is insofar the generated relief shape.

In the relief structure, the relief form of the relief elements in the first embodiments is uniform. In particular, the relief elements are formed differently only by the modification. Previously are relief elements with identical relief form in the relief structure next to each other. In second embodiments, the relief shapes of the relief elements already differ from each other in the relief structure. Preferably, the relief elements differ, but the different relief elements do not yet form an optically variable structure. It is only through the selective modification of the relief elements that the observer recognizes the visual variability. The relief elements of a relief structure may differ in their relief shape or size (or base area). The relief elements in a relic efstruktur may be different areas or different in a repeating pattern, each different in terms of relief shape and / or size. The sub-steps for generating the relief shape are preferably carried out by means of additive printing. In particular, it is possible to print by means of an inkjet process, wherein preferably (UV) curable ink is printed and (UV) cured. The creation of the relief elements can also be done by means of (laser) stereolithography. As an alternative to printing, the relief shape could be generated additively by means of selective laser sintering when creating the relief elements.

The sub-steps of creating can also be done by screen printing or gravure. By means of screen printing or gravure printing, relief elements are preferably produced with a height of 20-80 μπ / s. Several round-round or flat-flat screen printing steps can be combined. For example, in a first partial step, a relief partial element or a screen printing layer with a thickness of 30 μm is produced. In a second sub-step, 20 μπ and in a last screen printing sub-step 10 μη material application. Finally, the modification is printed as a color layer on the structures (by means of, for example, inkjet, offset, gravure printing).

As a rule, the same material is added in the substeps. The sub-steps within the relief element can be executed differently. In particular, the substeps may be performed differently with respect to the amount of added material and / or with respect to a process parameter for the added material. As a process parameter, in particular a temperature and / or a curing of a curable material can be varied. The material preferably has higher temperature increased viscosity. Thus, by choosing the temperature different relief partial elements are added (temperature 1 => round relief partial element, temperature 2 => oval relief partial element and temperature 3 => flat partial element). Likewise, the added material can be cured differently in the partial steps, for example immediately completely cured, pre-cured or uncured. An example, full surface, complete curing can be done in a later step, especially after an overlapping sub-step. The material applied in the partial steps is preferably a radiation-hardening material (UV / IR-curing). In general, the material is opaque, but in embodiments, transparent material can also be used. Preferably, the material is - at least on its surface - shiny or reflective, especially metallic reflective. The relief element can thus be made reflective or by a reflective coating. It is also conceivable, first apply first material and only in final substeps (for the visible surface of the relief element) to use reflective material. If the relief elements are produced, for example, in shaping substeps with a first relief material and the relief structure is coated in an additional step, the coating can be a smoothing coating and / or a coating and / or a reflective coating. The relief partial elements of at least one relief element, preferably several relief elements in one area, particularly preferably all relief elements of the relief structure, are coated together.

Alternatively or additionally, the relief elements are created in several preforming substeps with a first relief material and in a final, smoothing sub-step created with a second smoothing relief material. The preforming and smoothing sub-steps thus form the shaping sub-steps for the relief element. The smoothing relief material (or the coating) may include coloring / effect pigments and / or reflective pigments. Particularly preferably, the pigments in the material (its solvent and / or binder) are floating. Floating pigments are also referred to as leafing pigments. The pigments thus accumulate after application of the material on top of the binder.

The selective modification of the relief structure takes place

- By dyeing the relief structure, in particular by means of printing, or

- By further, modifying substeps of the additive method.

Selective dyeing of the relief structure can be effected in particular by printing or lasering. The added material may be a laser-sensitive material in (some or all of) sub-steps. Alternatively, a coating with laser-sensitive material. The selective modification takes place in particular in a modification grid, which is adapted to the grid of the relief elements. Only preferred are the rasters identical. The selective modification can also take place by means of further additive substeps. Reference is made, for example, to DE 102011114647 AI.

The selective modification is preferably carried out by printing lines on the relief structure in at least one color, particularly preferably alternately different monochrome. The lines occupy between 40-90% of the surface of the additively generated relief element or the relief structure. Particularly preferably, the different colored lines, in the CIE-LAB color space, differ in their hue. Particularly preferred is the difference between the shades of adjacent lines by at least 40 units for the values | a | and / or | b | of the CIE-LAB color space apart.

The step of selectively modifying makes the relief structure optically variable. In particular, a change of subject and / or motive movement can thereby be generated for the viewer. Depending on the viewing angle, the subject shown may disappear (or become visible to the observer) or switch to another subject or move. In particular, pumping movements, rotating movements or linear movements are known as movements.

In advantageous embodiments is not - as previously assumed - created the entire relief structure in its full height additive. The relief structure may include a embossing portion and a formative portion created thereon. Preferably, the embossed portion of the relief elements is formed from identical embossing elements. Starting from a uniform embossed structure can thus be formed a relief structure with different relief elements. Preferably, the uniform embossed structure is supplemented only in a range additive to the relief structure. Alternatively, the embossed portion of the relief elements may also be formed from different embossing elements. In particular, an embossed structure with differently oriented flat relief elements can be provided in a region with the relief portion. The height of the relief elements is between 5 and 500 μηι. Preferably, a height of the relief element of 100 μπι to 300 μπ \ is generated. More preferably, the relief element has an edge with slopes of 5 to 85 degrees, more preferably from 40 to 85 degrees. The present method can also be used to create relief elements with novel relief shapes. The partial steps generate the locally different height of the relief elements. In contrast to the embossing but now also an undercut can be generated. Embossed elements can be created with relief shapes or partial surfaces in the angular range of +/- 90 degrees to the plane of the elements. Maximum vertical (90 degrees) can in particular be a side wall of the embossed relief element. In the present case, it is now possible to produce relief elements having a relief shape which, in sections, has an angle of more than 90 degrees to the plane, in particular more than +90 degrees in a first section and more than -90 degrees in a second section. Preferably, the relief structure comprises at least two relief elements with a relief shape, which have an angle of more than 90 degrees to the plane in a section, wherein the two sections have different, preferably opposite, orientations.

In preferred embodiments, a primer is first applied, for example sprayed on, before the relief material is applied additively. The primer causes a smoothing and / or better adhesion.

In further preferred embodiments, the optically variable element comprises additional information which can be recognized by means of UV or IR light. The relief material, the material of the modification or the imprint are IR and / or UV active (in particular absorbent or luminescent).

The relief structure may comprise, in addition to the additively created relief elements, further relief elements which have been produced in particular by means of (blind) embossing or intaglio printing. The present optically variable element comprised a relief structure formed from a plurality of adjacent in a plane relief elements, the relief elements have a non-planar-parallel relief shape; and a modification (for example coloring) coloring of the relief structure, wherein the modification and the relief shape of the relief elements are coordinated with one another such that for a viewer the modified relief structure shows different representations depending on the viewing angle. The relief elements comprise additively created relief partial elements which determine the relief shape of the relief element.

The optically variable element can be produced as described above. It can be generated both on an intermediate carrier to be transferred from the subcarrier to a target substrate or generated directly on a target substrate. The optically variable element can be used in particular as a security element for value documents, such as banknotes or passports, or as a design element for packaging.

Further exemplary embodiments and advantages of the invention are explained below with reference to the figures, in the representation of which a representation true to scale and proportion has been dispensed with in order to increase the clarity.

Show it:

1 shows a value document with a plurality of optically variable elements;

Fig. 2a, b, c three relief elements of different relief form with imprint in each case in cross section and in plan view; Fig. 3a, b, c three additively generated relief elements with corresponding relief shape in cross section;

4 shows an additively produced relief element with smoothing, reflective coating in cross section;

Fig. 5a, b, two honeycomb-shaped, purely additive generated relief elements in

Cross section and in plan view; Fig. 6a, b two different honeycomb-shaped, relief elements with additive produced share on uniform embossing in cross-section and in plan view; two different honeycomb-shaped, relief elements with partly additive produced share on non-uniform embossing in cross-section and in plan view; and schematic representation of an apparatus for producing an optically variable element with additive substeps.

1 shows a value document 1, such as a banknote, which is provided with a plurality of different types of optically variable security elements 6, 7, 8, 9. A substrate 2 of the value document 1 has an imprint 3, which covers in particular all areas outside the security elements 6, 7, 8, 9. The optically variable security element 6 is a patch that has been transferred to the substrate. Such a patch can be designed with or without its own carrier layer, such as film. The security element 6 is regularly by means of pressure and / or heat, for example by means of a heat sealing lacquer, fixed on the substrate. The optically variable security element 7 was created directly on the substrate 2 (or its imprint 3). The optically variable security element 8 is a security thread which lies on the substrate 2, is completely embedded therein (and is only visible through openings / windows in the substrate) or is partially embedded in the substrate and lies partially thereon. The optically variable security element 9 is arranged overlapping with, here completely in, the security element 8. It can be a locally created or transmitted element.

Each of the optically variable elements 6, 7, 8, 9 may have been constructed according to the present method.

FIGS. 2 a to 2 c show three examples of relief elements 10 with imprint 20 for optically variable security elements with a relief structure. The relief elements 10 are each shown in cross section (upper half of the illustration) and in plan view (lower half of the illustration). The relief elements 10 differ in their relief shape from each other. In addition, the imprint 20 is designed differently.

FIG. 2 a shows a relief element 10 with a triangular cross-section, which is of line-shaped design. In the relief structure, a large number of the linear relief elements lie parallel to one another. The imprint 20 is punctiform, for example, as part of a screened imprint, applied to an edge of the relief element 10. A plurality of points, which are applied on the same flank, forms an optically variable motif, which the observer sees only at certain viewing angles (from the right or from above) or remains hidden from him at certain viewing angles (from the left). Fig. 2b shows a relief element 10 with an oval cross-section. The relief elements 10 and 11 are - like knobs formed and - arranged side by side in the relief structure. The imprint 20 is designed as a linear example in FIG. 2b and extends - preferably not parallel over the relief structure of knob-shaped relief elements 10, 11. Among other things, the non-parallel arrangement leads with appropriate adaptation of relief structure and imprint to a Motion effect (moving subject). For the observer, when the viewing angle is changed, a moving motif is created which, in particular, moves in a rotating, pumping or linear manner. Such an effect is described in more detail, for example, in WO 2016/020066 A2.

For example, WO 2006/018232 AI shows to Fig. 2b a variety of alternative relief shapes for the relief demesem, in particular pyramidal with different bases, cones, cylindrical or oval (possibly as a stump) and considered non-linear imprints, similar to in Fig. 2a enable a motif change. By contrast, DE 102011114647 A1 is an example of another possible form of modification of the relief structure which is not formed by a print (or alternatively a laser). In a regular relief structure individual relief elements are modified in their relief form. Fig. 2c shows a relief element 10, which is designed with a flat, directed surface. In Fig. 2c, the surface is inclined at a certain angle to the right and provided with a full-surface imprint 20. The orientation is symbolized by an arrow in the lower illustration. The imprint could also be part of the surface, for example punctiform, designed. An adjacent relief element 11 may, as shown, have a different (or the same) orientation and (also have a similar or different-colored imprint) or - as shown - be free of an imprint.

The relief elements may differ from each other in particular with respect to orientation and angle of inclination. For example in WO

2013/045054 AI such a relief structure is described in more detail. The directional surface of the relief element 10 is in particular a reflective surface.

The relief element 10 is honeycomb-shaped in Fig. 2c, but may also have rectangular, square or similar also surface-filling shape in plan view. The relief structure comprises a plurality of corresponding directly adjacent relief elements whose orientation can be selected individually.

FIGS. 3a to 3c show how the relief elements 10 shown in FIGS. 2a to c can be created additively from different relief subelements.

Fig. 3a shows a triangular relief element 10, which is generated by additive printing of three relief partial elements 31, 32 and 33. The same relief material is preferably printed one above the other in succession in the three partial steps. In Fig. 3a, the relief partial elements 31, 32, 33 have been generated differently, so in particular are not identical in shape. By suitable choice of the pressure parameters amount of material and / or material temperature different relief partial elements can be generated one above the other. The relief partial element 31 was at higher Temperature (and thus greater viscosity of the material) and optionally produced with a larger amount of material. Due to the increased viscosity, a flat and wide relief partial element 31 forms. The partial relief element 32 was generated at a second (eg normal) temperature and optionally with a second amount. It forms a rather round relief partial element 32. The relief partial element 33, however, was generated with lowered material temperature. The result is an exaggerated narrow relief partial element 33. The relief element 10 comprises at least the three overlapping relief partial elements, which are recognizable in cross section. It can be seen that the relief shape of the relief element 10 is determined by the substeps of the additive method. The

Relief element may include a plurality of (linear) adjacent relief partial elements or may be designed linear.

The relief partial elements 31, 32, 33 can be two-stage, by means of (UV)

Irradiation, cured. In particular, each relief partial element 31, 32, 33 can be individually cured after its application. The hardened relief partial elements 31, 32, 33 can then be completely cured together. The relief partial elements 31, 32, 33 may, for example, have been produced one after the other with a (the same) print head or also successively with different print heads.

Fig. 3b shows a semicircular (or knob-shaped) relief element 10, which comprises three relief partial elements 34, 35 and 36. The relief shape of the relief element 10 is again generated by means of correspondingly adapted sub-steps of the printing. The relief material and / or the selected temperature lead to an adaptation of the relief partial elements 35, 36 to the shape of the first relief partial element. An adaptation of the parameter application width of the added material could also have been varied in the present case. It In each case the same material is applied additive in at least three partial steps in order to produce the relief element with the relief mold.

Fig. 3c shows the directional surface of the relief element 10 of Fig. 2c, which was generated additive. The relief element 10 comprises a plurality of relief partial elements 37, 38 and 39. In the illustration shown, the relief partial elements are in turn designed or produced differently. For example, the relief partial elements 37 are produced with more material and increased temperature. The Reliefteilelemente 38 are created with average amount of material and average application temperature. The relief partial elements 39 are produced as flat relief partial elements, for example by a small amount and a further elevated temperature. Alternatively, relief elements 39 delimiting the relief element are produced with another relief material. The other relief material may preferably have reflective properties if the actual relief material is, for example, (transparent or opaque and) non-reflective.

Each of the relief elements 10 from FIGS. 3 a to 3 c (as well as the other figures) is one of the plurality of relief elements of a relief structure which, as described above, together with a modification of the relief structure, for example by an imprint, serves as an optically variable element.

4 shows a further preferred variant for producing a relief element 10. A plurality of relief partial elements 41, 42 is created additively in order to determine the relief shape. In a final step, the relief element (individually or together with a plurality of relief elements) is provided with a smoothing, preferably reflective, coating 45. The relief elements 10 should reflect primarily according to their orientation. The surface which is formed by the relief partial elements 42, Even if reflective material is already used, it may not reflect adequately. In order to achieve a sufficiently directed reflection, the smoothing coating 45 takes place. In the present case, the coating comprises floating, reflecting pigments 46. The pigments therefore accumulate on the binder 47 on the upper side of the coating 45. A surface which reflects in a particularly well-directed manner is formed.

FIGS. 5 to 7 show variants in which relief elements 11, 12 are created completely additively (FIG. 5) or are formed from a stamping component and an additive-produced component (FIGS. 6 and 7).

Fig. 5a shows in cross-section - along the line A of Fig. 5b - two relief elements 11 and 12. Both relief elements are formed in substeps additive from the relief sub-elements 51, 52 and 53. The partial steps are adapted so that the relief element 11 has a first inclination angle (35 degrees) and the relief element 12 has a second inclination angle (25 degrees). The orientation of the adjacent relief elements 11, 12, as indicated in Fig. 5b by the arrows, identical. Both relief elements are completely created by additive substeps. It would also be conceivable to provide a first subregion (not shown) as an embossed relief and to create the relief elements completely (and / or partially) in an additive manner - partly illustrated - in the second subregion.

Fig. 6a again shows in cross-section - along the line A of Fig. 6b - two relief elements 11 and 12. The relief elements 11, 12 comprise a embossing portion 160 and a pressure portion 60. Similar embossing elements 161 form the embossed portion of the relief structure. By different pressure components 60, which are generated additively by relief partial elements 61, 62, different relief elements 11, 12 are formed. The relief element 12 has, as indicated in Fig. 6b, a different orientation (down) and a different angle of inclination (25 degrees) as the relief element 11 (35 degrees and to the right). A uniform relief structure, with similar relief elements 161, can thus be designed individually for each relief element.

Fig. 7a, however, shows in cross-section - along the line A of Fig. 6b - two relief elements 11 and 12, which comprise a nonuniform embossing portion 170 and a pressure component 70. The embossing elements 171 and 172 are already aligned differently and different heights. The additively added relief partial elements 71, 72 generate the relief shape of the relief element 11. In the example shown, the relief element 172 remains unchanged.

FIG. 8 shows schematically a device for producing the optically variable element. Value documents 1 are successively supplied to printing units 81, 82, 83 and 86 on a conveyor belt 88. The printing units 81, 82, 83 preferably each comprise a printing unit and a curing unit. The relief printing units 81, 82 and 83 additively print the relief material onto the document of value. Each relief printing unit generates at least one relief partial element. As already indicated above, a parameter of the printing process can be varied during printing. In particular, temperature and amount of material are such parameters. Preferably, the relief material is curable, so it is added and then cured by the relief pressure unit. The degree of hardening forms another parameter which can be used flexibly.

An optional curing unit useful in two-stage curing is not shown, but may be used to fully cure the relief elements individually pre-cured in the embossing units 81, 82 and 83, particularly before the selective modification takes place. After the relief printing unit 83 is on the substrate before the relief structure with relief elements. A motif printing unit 86 selectively prints at certain positions a motif that is visually variable by the relief structure for the viewer.

The ink of the relief printing unit comprises a liquid, low-viscous and optionally pigmented substance prepared by using a die-coating technique, e.g. the ink-jet technique is applied. It is modified in its aggregate state, preferably hardened. This happens e.g. physically by solvent removal and / or chemically by polymerization or UV curing to a solid material.

In the printing units, it is optionally possible to use different materials, which differ in particular primarily with respect to their viscosity. Preferably, a uniform base material is used, which is different viscous by different admixtures. For example, the first printing unit 81 can apply a viscous material with a large-diameter printing nozzle and a high-viscosity material in the printing unit 83 with a smaller printing nozzle. Optionally, the applied material comprises a solvent which evaporates after application.

To apply various relief materials, it is advantageous to apply them in separate systems to avoid process media mixing, wherein one or more nozzles, printing or spray heads can be used, which are mounted one behind the other parallel to the substrate travel direction (eg along a paper web or along a cylinder ). If different or the same materials are added one after the other exactly next to and above each other, it is necessary to harden or cure the individual layers. The application of the following relief element elements takes place in material-related different time intervals. You can alternately in different directions or, with sufficient spatial distance of the different media leading pressure or spray heads are applied in the same direction. Preferably, this spatial distance is selectively adjustable according to the required time interval in the y- and / or x-direction by variably placeable pressure or spray heads and / or traverses. However, it is also possible to apply only one partial element with each roller revolution and to pass the substrate on to the next production step only after completion.

With other additive manufacturing processes, such as selective laser melting and electron beam melting for metals or selective laser sintering for polymers, ceramics and metals, functional relief structures can be generated which display different appearance colors or "tilt image information" at given viewing angles as an example in more detail.

In such a method, individual material layers are cured by means of laser and the workpiece is built up layer by layer. The powder is applied to a building platform with the aid of a doctor blade or roller over the entire surface in a thickness of 1 to 200 μπι. The layers are sintered or melted step by step into the powder bed by triggering a laser beam corresponding to the layer contour of the component. The build platform is now slightly lowered and a new layer raised. The powder is made available by lifting a powder platform or as a stock in the squeegee. The processing is done layer by layer in vertical direction, which makes it possible to create also undercut contours. The energy that is supplied by the laser is absorbed by the powder and leads to a locally limited sintering of particles while reducing the total surface area. This creates any three-dimensional geometries that allow flank angles with undercuts.

With the help of this technique one could laser-sintered prototypes or individual parts directly with a functional "security feature", which shows eg a manufacturer label as viewing angle dependent tilting image Beside securities, product packaging which can be functionalized in with a tactile inkjet printing, there are other alternative starting materials such as produced An alternative to the complete production of the relief elements by means of inkjet is that the relief elements partially (analogous to Fig. 6 and 7) with a vacuum thermoforming process, also called vacuum forming or Thermof orming called in one In contrast to injection molding, in which heated plastic is injected into a cavity (mold), the starting material is a plastic plate which is heated up to the thermoelastic state and then onto the tool sucked. After cooling, the deformed plate retains the given shape. Usually plates are used in thicknesses of 0.3 to 10 mm. This means that everything from light packaging to stable objects is possible. Lich. After formation of the nub structure, inkjet-resolved, color-resolved information can be applied to the material, which in turn generates tilt-dependent optical variability.

LIST OF REFERENCE NUMBERS

value document

substratum

Imprint, 7, 8, 9 Security element 0, 11, 12 Relief element

0 Modifying print 1, 32, ... 39 Relief parts

1, 42, 51 - 53 Relief parts

5 leveling layer

6 metal pigments

7 Binder 0, 70 pressure content

1, 62, 71, 72 relief partial elements

60, 170 embossed portion

61, 171, 172 Embossing element 1, 82, 83 Relief printing unit 6 Motive printing unit 8 Transport path

Claims

Patent claims

1. A method for producing an optically variable element (6, 7, 8, 9), comprising the steps of:

- Creating a relief structure formed from a plurality of in a plane adjacent relief elements (10, 11, 12), wherein the relief elements have a non-parallel to the plane relief shape;

- Selective modification of the relief structure, wherein the modification and the relief shape of the relief elements are coordinated so that for a viewer, the modified relief structure (10, 20) shows different representations depending on the viewing angle;

characterized in that

the relief structure is at least partially created by means of an additive process,

wherein for relief elements (10,11,12) in each case a plurality of sub-steps of the additive method are performed, and

wherein the sub-steps determine the relief shape of the relief element (10,11,12).

2. The method according to claim 1, characterized in that

- The relief shape of the relief elements in the relief structure is uniform, or

- The relief shapes of the relief elements in the relief structure differ, especially in terms of one of the parameters alignment and / or inclination of a reflective relief element surface.

3. The method according to claim 1 or 2, characterized in that the partial steps take place by means of additive printing.

4. The method according to any one of claims 1 to 3, characterized in that in the substeps at least three superimposed relief partial elements are generated.

5. The method according to any one of claims 1 to 4, characterized in that the partial steps are performed differently within the relief element, in particular different with respect to the amount of added material and / or a process parameter for the added material.

6. The method according to any one of claims 1 to 5, characterized in that in the partial steps material is applied that is UV-curing and / or reflective and / or opaque and / or colored.

7. The method according to any one of claims 1 to 6, characterized in that the selective modification of the relief structure takes place

by coloring the relief structure, in particular by means of printing, or

- By further, modifying substeps of the additive method.

8. The method according to any one of claims 1 to 7, characterized in that the relief elements are created in the shaping substeps with a first relief material and in an additional step, the relief structure is coated, wherein the coating (45)

a smoothing coating and / or

a region-covering or full-surface, coating coating and / or

- Is a reflective coating.

9. The method according to any one of claims 1 to 8, characterized in that the relief elements in a plurality of first, preforming substeps be created with a first relief material and created in a final, smoothing sub-step with a second smoothing relief material.

10. The method according to any one of claims 1 to 9, characterized in that the smoothing relief material color pigments and / or reflective pigments (46), which are in particular floating in the material.

11. The method according to any one of claims 1 to 10, characterized in that the relief elements (11, 12) from a embossing portion (160, 170) and an additive produced thereon, forming portion (60, 70) are formed.

12. The method according to claim 11, characterized in that the embossing portion (160) of the relief elements of identical embossing elements (161) is formed.

13. The method according to claim 11, characterized in that the embossment (160) of the relief elements of different embossing elements (171,

172) is formed.

14. Optically variable element (6, 7, 8, 9), with:

a relief structure formed from a multiplicity of relief elements (10, 11, 12) lying next to one another in a plane, the relief elements having a non-plane-parallel relief shape;

- A modification of the relief structure, wherein the modification and the relief shape of the relief elements are coordinated so that for a viewer, the modified relief structure depending on the viewing angle shows different representations;

characterized in that

the relief elements (10, 11, 12) comprise additively created relief partial elements (31, 32, 33) which determine the relief shape of the relief element.

15. An optically variable element (6, 7, 8, 9) according to claim 14, in particular produced by a method according to one of claims 1 to 13.