Multi-layer body and method for the production thereof

Abstract

A method for the production of a multilayer body, in particular a security element, includes: a) producing a metal layer on a substrate; b) partial demetalization of the metal layer to form a first item of optical information in a first area of the multilayer body; c) applying a partial lacquer layer in a second area of the multilayer body to form a second item of optical information, wherein the partial lacquer layer extends at least partially beyond the metal layer; d) structuring the partial metal layer in the second area using the partial lacquer layer as mask.

Claims

1. A method for the production of a multilayer body in the form of a security element, comprising the following steps: a) producing a metal layer on a substrate; b) partial demetalization of the metal layer to form a partial metal layer comprising a first item of optical information in a first area of the multilayer body; c) applying a partial lacquer layer in a second area of the multilayer body to form a second item of optical information, wherein the partial lacquer layer extends at least partially beyond the metal layer; d) structuring the partial metal layer in the second area using the partial lacquer layer as mask, wherein the partial metal layer is either selectively retained or selectively removed in the areas which are covered by the partial lacquer layer.

2. The method according to claim 1, wherein the partial demetalization in step b) takes place through etching.

3. The method according to claim 2, wherein the partial lacquer layer is an etch resist, or comprises at least one etch resist.

4. The method according to claim 3, wherein the etch resist is a lacquer that comprises: binders; colored or non-colored pigments and/or effect pigments; thin-layer film systems; cholesteric liquid crystals; dyes; and/or metallic or non-metallic nanoparticles.

5. The method according to claim 1, wherein before the application of the partial lacquer layer in step c), the metal layer is partially demetalized in the second area.

6. The method according to claim 5, wherein the partial demetalization of the metal layer in the second area takes place through etching.

7. The method according to claim 6, wherein, in the second area, an etching base, is printed onto the metal layer by flexographic printing.

8. The method according to claim 6, wherein, before the etching, a photoresist is applied to the second area and is exposed using an exposure mask.

9. The method according to claim 8, wherein the exposure mask is formed by a partial lacquer layer applied to the substrate before the application of the metal layer.

10. The method according to claim 6, wherein, before the etching, an etch resist is applied partially to the second area and is removed again after the etching.

11. The method according to claim 5, wherein the partial demetalization of the metal layer in the second area takes place through lift-off.

12. The method according to claim 5, wherein the partial demetalization of the metal layer in the second area takes place through laser ablation.

13. The method according to claim 5, wherein the partial demetalization of the metal layer in the second area takes place through printing of a partial oil layer before the application of the metal layer.

14. The method according to claim 1, wherein the substrate is or comprises a replication layer with a surface relief formed in a surface facing the metal layer.

15. The method according to claim 14, wherein the surface relief introduced into the replication layer forms a hologram, a linear or crossed sinusoidal diffraction grating, a linear or crossed single- or multilevel rectangular grating, a zero-order diffraction structure, an asymmetrical relief structure, a blazed grating, an isotropic or anisotropic matt structure, or a light-diffracting and/or light-refracting and/or light-focusing micro- or nanostructure, a binary or continuous Fresnel lens, a binary or continuous Fresnel freeform surface, a microprism structure or a combination structure thereof.

16. The method according to claim 14, wherein the surface relief comprises a partial area with a depth-to-width ratio of from 0.15 to 1.5, which is complementary to the first item of optical information.

17. The method according to claim 16, wherein, for the partial demetalization of the metal layer in the first area, a photoresist is applied to the metal layer and is exposed from the side of the substrate and the metal layer is then partially demetalized by etching.

18. The method according to claim 1, wherein at least one further partial lacquer layer is applied to the multilayer body to form at least one further item of optical information.

19. The method according to claim 18, wherein the at least one further partial lacquer layer comprises: colored or non-colored pigments and/or effect pigments; thin-layer film systems; cholesteric liquid crystals; dyes; and/or metallic or non-metallic nanoparticles.

20. The method according to claim 19, wherein the colorants can be excited in the ultraviolet and/or infrared spectrum to fluorescence and/or phosphorescence in the visible spectrum.

21. The method according to claim 1, wherein the partial lacquer layer and/or the at least one further partial lacquer layer is applied by intaglio printing, flexographic printing, screen printing, pad printing, offset printing, letterpress printing, ink-jet printing and/or laser printing.

22. The method according to claim 1, wherein the partial lacquer layer and/or the at least one further partial lacquer layer is radiation-cured by UV or electron-beam radiation.

23. The method according to claim 1, wherein at least one individualization feature is applied to the multilayer body by ink-jet and/or laser printing.

24. A multilayer body in the form of a security element, wherein the multilayer body comprises a substrate, a partial metal layer and a partial lacquer layer, and wherein the partial metal layer forms, in a first area, a first item of optical information and the partial lacquer layer forms, in a second area, a second item of optical information and the partial lacquer layer is arranged in the second area in register with the partial metal layer, wherein the partial lacquer layer extends both into areas which are covered by the partial metal layer and into areas not covered by the partial metal layer.

25. The multilayer body according to claim 24, wherein the substrate is or comprises a replication layer with a surface relief, which is formed in a surface facing the partial metal layer.

26. The multilayer body according to claim 25, wherein the surface relief introduced into the replication layer forms a hologram, a linear or crossed sinusoidal diffraction grating, a linear or crossed single- or multilevel rectangular grating, a zero-order diffraction structure, an asymmetrical relief structure, a blazed grating, an isotropic or anisotropic matt structure, or a light-diffracting and/or light-refracting and/or light-focusing micro- or nanostructure, a binary or continuous Fresnel lens, a binary or continuous Fresnel freeform surface, a microprism structure or a combination structure thereof.

27. The multilayer body according to claim 25, wherein the surface relief comprises a partial area with a depth-to-width ratio of from 0.15 to 1.5, which is complementary to the first item of optical information.

28. The multilayer body according to claim 24, wherein the substrate comprises a wax layer and/or a release layer and/or a protective lacquer layer.

29. The multilayer body according to claim 28, wherein a layer thickness of the replication layer and/or of the protective lacquer layer is 0.3 m to 3 m.

30. The multilayer body according to claim 28, wherein a layer thickness of the wax layer and/or of the release layer is 0.01 m to 0.3 m.

31. The multilayer body according to claim 24, wherein the substrate comprises a releasable carrier ply made of PET.

32. The multilayer body according to claim 31, wherein a layer thickness of the carrier ply is 5 m to 75 m.

33. The multilayer body according to claim 24, wherein the partial metal layer consists of aluminum, copper, chromium, silver and/or gold.

34. The multilayer body according to claim 24, wherein a layer thickness of the metal layer is 10 nm to 200 nm.

35. The multilayer body according to claim 24, wherein, in the first area, a transparent protective lacquer layer made of PVC, PET, acrylate, nitrocellulose, cellulose acetobutyrate or mixtures thereof is arranged on the partial metal layer.

36. The multilayer body according to claim 35, wherein a layer thickness of the protective lacquer layer is 0.2 m to 10 m.

37. The multilayer body according to claim 24, wherein at least one further partial lacquer layer is provided which forms a further item of optical information.

38. The multilayer body according to claim 24, wherein a layer thickness of the partial lacquer layer and/or of the at least one further partial lacquer layer is 2 m to 10 m.

39. The multilayer body according to claim 24, wherein the partial lacquer layer and/or the at least one further partial lacquer layer comprises: colored or non-colored pigments and/or effect pigments; thin-layer film systems; cholesteric liquid crystals; dyes; and/or metallic or non-metallic nanoparticles.

40. The multilayer body according to claim 39, wherein the colorants can be excited in the ultraviolet and/or infrared spectrum to fluorescence and/or phosphorescence, in the visible spectrum.

41. The multilayer body according to claim 24, wherein the first and/or second and/or further item of optical information is formed in the shape of at least one motif, guilloche pattern, symbol, image, logo or of alphanumeric characters, numbers and/or letters.

42. The multilayer body according to claim 24, wherein the first and/or second and/or further item of optical information is formed in the shape of a one- or two-dimensional line and/or dot grid, wherein the line and/or dot grid has a grid spacing of less than 300 m and of more than 25 m.

43. The multilayer body according to claim 24, wherein the first and/or second and/or further item of optical information comprises at least one machine-readable barcode.

44. The multilayer body according to claim 24, wherein on the side of the multilayer body facing away from the substrate, an adhesive layer, made of PVC, polyester, acrylate, cellulose ester, natural resin, ketone resin, polyamide, polyurethane, epoxy resin or mixtures thereof, is arranged.

45. The multilayer body according to claim 44, wherein a layer thickness of the adhesive layer is 0.5 m to 25 m.

46. A bank note, security, identity document, visa document, passport or credit card with a multilayer body according to claim 24.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention is now explained in more detail with reference to embodiment examples. There are shown in:

(2) FIG. 1A-B A first intermediate product during the carrying out of an embodiment example of a method for producing a multilayer body in schematic top view and sectional representation;

(3) FIG. 2A-B A second intermediate product during the carrying out of an embodiment example of a method for producing a multilayer body in schematic top view and sectional representation;

(4) FIG. 3A-B A third intermediate product during the carrying out of an embodiment example of a method for producing a multilayer body in schematic top view and sectional representation;

(5) FIG. 4A-B A fourth intermediate product during the carrying out of an embodiment example of a method for producing a multilayer body in schematic top view and sectional representation;

(6) FIG. 5A-B A fifth intermediate product during the carrying out of an embodiment example of a method for producing a multilayer body in schematic top view and sectional representation;

(7) FIG. 6A-B A multilayer body manufactured by means of an embodiment example of a method for producing a multilayer body in schematic top view and sectional representation;

(8) FIG. 7 An embodiment example of a security document with a multilayer body according to FIG. 6.

DETAILED DESCRIPTION OF THE INVENTION

(9) For the production of a multilayer body labeled as a whole with 1, which can be used as security element for bank notes, securities, identity documents, visa documents, certificates, tickets or protected product packaging, first of all a carrier layer 11 is provided with a transfer ply 12.

(10) The carrier layer 11 preferably consists of polyester, in particular PET and has a layer thickness of from 6 m to 75 m, preferably 12 m to 25 m. The transfer ply 12 can comprise a wax layer, a release layer, a protective lacquer layer and a replication layer, which forms the surface of the transfer ply 12 facing away from the carrier layer 11.

(11) Preferably a layer thickness of the replication layer and/or of the protective lacquer layer is 0.3 m to 3 m, preferably 0.5 m to 1.5 m. Preferably a layer thickness of the wax layer and/or of the release layer is 0.01 m to 0.3 m, preferably 0.1 m to 0.2 m. Alternatively to the wax layer and/or the release layer, layers made of silicone or an acrylic polymer/acrylic copolymer can also be used. The release layer can also be part of the protective lacquer layer.

(12) The replication layer consists, for example, of a thermoplastic or a radiation-curable or temperature-curable replication lacquer. Diffractive structures are then formed in the replication layer, for example by stamping with a metallic stamping tool.

(13) The surface relief introduced into the replication layer preferably forms an optically variable element, in particular a hologram, Kinegram or Trustseal, a preferably linear or crossed sinusoidal diffraction grating, a linear or crossed single- or multilevel rectangular grating, a zero-order diffraction structure, an asymmetrical relief structure, a blazed grating, a preferably isotropic or anisotropic matt structure, or a light-diffracting and/or light-refracting and/or light-focusing micro- or nanostructure, a binary or continuous Fresnel lens, a binary or continuous Fresnel freeform surface, a microprism structure or a combination structure thereof.

(14) In addition or as an alternative to such structures, the surface relief forms, in a first area 2 of the multilayer body, a first item of optical information which is formed by structures with a depth-to-width ratio of from 0.15 to 1.5, preferably from 0.2 to 0.5, and a spatial frequency preferably of at least 1000 lines/mm to 5000 lines/mm.

(15) After the provision of the carrier layer 11 and transfer ply 12, as shown in FIG. 1, a metal layer 13 is produced on the replication layer of the transfer ply 12, which can take place for example by vapor deposition on a substrate, not shown. The vapor deposition preferably takes place in a vacuum by thermal evaporation, by means of electron-beam evaporation or also by means of sputtering.

(16) The metal layer 13 can preferably consist of aluminum, copper, chromium, silver and/or gold and/or an alloy thereof. The partial metal layer can also consist, in areas, of different metals in order to produce particular optical effects.

(17) Expediently, a layer thickness of the metal layer 13 is 10 nm to 100 nm, preferably 15 nm to 35 nm, in particular when aluminum is used.

(18) Then, the metal layer 13 is partially removed by means of known methods, for example by the partial application of an etch resist after the vapor deposition and subsequent etching including removal of the etch resist; by the partial application of a washcoat before the metalization and washing off (lift-off) after the metalization; or by the partial application of a photoresist after the metalization and then exposure and subsequent removal of the exposed or unexposed components of the photoresist depending on the type (positive, negative) of the photoresist.

(19) Through the depth-to-width ratio of the surface relief of the replication layer in the first area 2, the transparency of the metal layer 13 applied to the surface relief can be varied. This different transparency can therefore subsequently itself be used as exposure mask in order to structure a photoresist applied to the metal layer 13. During the subsequent etching, the metal layer 13 in the first area 2 therefore remains in register with the first item of optical information 131 predefined in the replication layer.

(20) Alternatively, the substrate is not metalized over all of its surface, rather the metal layer 13 is partially produced in particular in the second area 3 of the multilayer body 1. Various methods are known for this, such as for example shielding by means of a concurrent mask or printing with an oil which prevents the deposition of the metal layer in the vapor deposition process.

(21) Therefore, the structuring of the metal layer 13 preferably takes place separately for the first area 2 and the second area 3, wherein in the second area preferably only a rough structuring is carried out. However, the structuring can also take place in a common workstep.

(22) As shown in FIG. 2, in the next method step a transparent protective lacquer 14 is applied to the metal layer 13 in the first area 2. In the following etching processes, this protects the already completely structured metal layer 13 in the first area 2. The layer thickness of the protective lacquer layer 14 is 0.2 m to 10 m, preferably 0.5 m to 1.5 m.

(23) In the second area 3, a partial lacquer layer 15 is printed on such that it extends beyond the metal layer 13 in this area, but also leaves parts of the metal layer 13 uncovered. The lacquer layer 15 forms a second item of optical information 151, in the example shown a guilloche pattern of fine lines. The printing of the lacquer layer 15 can also overlap areas of area 2 (not shown here).

(24) In the example shown in the figures, the lacquer layer 15 acts as an etch resist and preferably comprises a lacquer, which in particular comprises binders, dyes, pigments, in particular colored or non-colored pigments, effect pigments, thin-film layer systems, cholesteric liquid crystals and/or metallic or non-metallic nanoparticles.

(25) Suitable lacquers are formulated for example on the basis of PVC, polyester or acrylates. The partial lacquer layer 15 thus fulfils not only a protective function during the structuring of the metal layer 13 but can itself display a decorative effect. It is also possible for several different lacquers, for example with different colorations, to be used in order to produce further visual effects.

(26) After the application and curing of the lacquer layers 14 and 15, a further etching process takes place. This leads to the intermediate product shown in FIG. 3. In the first area 2, the structure of the metal layer 13 is retained because of the protective lacquer layer 14. In the second area 3, the metal layer 13 is removed where it is not covered by the partial lacquer layer 15.

(27) As can be seen in FIG. 3A, this leads to the line patterns of the partial lacquer layer 15, seen from the visible face of the multilayer body, that is from the direction of the carrier ply 11, being recognizable where they were not applied to the metal layer 13. Where the lacquer layer 15 was applied to the metal layer 13, the metal layer 13 remains and the line pattern of the lacquer layer 15 can be recognized as a metal structure. The line pattern of the second item of optical information 151 therefore transitions seamlessly between colored lacquer and metal.

(28) Then, a further partial lacquer layer 16 is applied which forms a further item of optical information 161. This is represented in FIG. 4. The lacquer layer 16 overlaps both the first area 2 and the second area 3. For the lacquer layer 16, a lacquer is used the dyes or pigments of which cannot be recognized in the visual spectrum but which can be excited to fluorescence and/or luminescence by UV irradiation. A suitable lacquer is composed, for example, from acrylate with nitrocellulose as film-former and with UV-active pigment mixed in. Such pigments can be, for example, Lumilux pigments from Honeywell. Furthermore, it is also possible to provide colorless or pigmented printing lacquers for different printing processes, such as for example intaglio printing, flexographic printing or offset printing, with pigments. Such lacquers are offered print-ready, for example, by Luminescence.

(29) The further item of optical information 161 can therefore only be recognized under a UV light source and serves as an additional security feature. Furthermore, the emission of the fluorescence can be different depending on the wavelength of the UV light source. Thus, for example, it can be red on excitation at 365 nm and green on excitation at a wavelength of 254 nm and thus serve as a further security feature. For example, the further item of optical information 161 can represent a machine-readable pattern such as a barcode.

(30) As FIG. 5 shows, a further partial lacquer layer 17 can now be applied. For this, a lacquer is again used the colorants of which can be recognized by the human eye. The further partial lacquer layer 17 forms a further item of optical information 171, here a pattern of stars, which partially overlies the items of optical information 131, 151 and 161 and forms a background for them.

(31) The lacquer layers 15, 16, 17 are preferably applied by intaglio printing, flexographic printing, screen printing, pad printing, offset printing, letterpress printing, ink-jet printing and/or laser printing. The layer thickness of the lacquer layers 15, 16, 16 is 0.3 m to 3 m, preferably 0.5 m to 1.5 m.

(32) After the printing, radiation-curing can take place, in particular by UV irradiation at wavelengths of from 200 nm to 415 nm. Before the individual printing steps, primers can also be applied to improve the layer adhesion. For this, lacquers based on PVC, polyester or acrylates in layer thicknesses of from 0.01 m to 1 m, preferably from 0.02 m to 0.2 m are suitable, for example.

(33) Finally, an adhesive layer 18 is also applied to the printed layers, with which the finished multilayer body 1 can be fixed onto a security document, for example. For example PVC, polyester, acrylates, cellulose ester, natural resins, ketone resins, polyamide, polyurethane, epoxy resins or mixtures thereof, are suitable as adhesive. The layer thickness of the adhesive layer is 1 m to 25 m, preferably 1 m to 15 m.

(34) In FIG. 6A, it can now be recognized how the individual layers of the multilayer body 1 interact. The background of the decoration is formed by the star-shaped patterns of the lacquer layer 17. Over these lies the item of optical information 161 which is only visible under UV irradiation and is formed by the lacquer layer 16. The foreground of the decoration is shaped by the guilloche lines of the first item of optical information 131 and the second item of optical information.

(35) In addition to these guilloche lines, the first and second items of optical information can also form further features. As can be seen from FIG. 6A, the first item of optical information 131 also comprises a circumferential microtext with contrast inversion based on asymmetrical structures. This contrast inversion can be implemented, for example, with blazed or so-called sawtooth structures. Here, one and the same blazed structure is used, for example, for the outline and the fill of the microtext, wherein these are mounted rotated by 180 with respect to each other. A typical light-dark contrast inversion thereby results: in the normal observation position, for example, the fill appears light and the outline dark; after a 180 rotation of the OVD in the plane, the outline now appears light and the fill dark. This visual effect is characterized by a high degree of security against forgery and a simple verifiability. Typical parameter values for the blazed structures to be used are numbers of lines in the range of from 500 lines/mm to 1500 lines/mm and structure depths in the range of from 200 nm to 500 nm. The contrast inversion can be realized with such colored blazed structures or also with rougher achromatic blazed structures.

(36) In the centre of the guilloche lines, further security features are arranged which are formed by the metal layer 13 interacting with the replication layer. These can be, for example, micro- or nanostructures, DACs (diffractive area codes), diffractive fine-line effects (e.g. transformations, conversions, pump effects, or the like) based on colored or achromatically acting microstructures, binary or continuous Fresnel freeform surfaces, image-flip effects, or also other security structures which can either be recognized with the naked eye, or with simple additional aids (e.g. a magnifier), or with special aids (e.g. a microscope), or purely machine-readable security structures.

(37) Further features, such as for example diffractive fine-line effects (e.g. transformations, conversions, pump effects, or the like) based on colored or achromatically acting microstructures, binary or continuous Fresnel freeform surfaces, image-flip effects, or also other security structures which can either be recognized with the naked eye, or with simple additional aids (e.g. a magnifier), or with special aids (e.g. a microscope), or purely machine-readable security structures, micro- or nanotext items of information, dynamic color effects or the like can also be provided in the area of the second item of optical information 151.

(38) In particular, micro- or nanotext items of information can be provided with an almost continuous variation in size in the range of from 3 m to 2 mm, preferably in the range of from 10 m to 500 m, further preferably in the range of from 20 m to 150 m.

(39) The multilayer body 1 can now be applied to a security document 4, for example an identity document, as represented in FIG. 7. This can take place, for example, by hot stamping or by lamination on or lamination in, back-injection molding, UV transfer (cold stamping). Laminating the multilayer body 1 into the security document 4 is also possible. The carrier can be pulled off after the application or remain on the substrate. Furthermore, the security element 4 can be protected by further applied plies or layers, for example by a protective film laminated over it. Furthermore, the security feature 4 can be transferred onto a further transfer ply in a first step and, in a next step, be transferred onto the substrate to be secured together with the transfer ply.

(40) In the embodiment example of a security document 4 represented in FIG. 7, the multilayer body 1 is applied in such a way that it overlaps an identification photograph 41, with the result that the latter cannot be removed without the security document 4 and/or the multilayer body 1 being destroyed.

(41) The multilayer body 1 can itself be partially overprinted in a further step with further security features 42, 43. This can take place, for example, by ink-jet printing, offset printing, letterpress printing or die stamping. The security features 42, 43 can also contain individualized items of information and ensure that the multilayer body 1 cannot be removed from the security document 4.

(42) Furthermore, in the area 44 of the security document, the necessary personalization information for the security document 4 can be printed on. A possible method consists in printing the personalization information by means of ink-jet printing. If the printing is also to take place over the security feature, in particular water-based inks require a special receptive layer or an ink receiving layer so that the printing can dry in a sufficiently short time. Such layers consist, for example, of a swellable layer, a microporous layer or a combination of the two. Swellable layers typically consist of polyvinyl alcohol, polyvinylpyrrolidone, gelatin derivatives or cellulose ester or also of mixtures thereof. Layer thicknesses typically lie in the range of from 3 m to 10 m. Porous layers consist, for example, of polyvinyl alcohols with large amounts of fillers. Such layers typically have layer thicknesses of from 5 m to 25 m, preferably of from 5 m to 15 m.

(43) Advantageously, such layers are part of the multilayer body 1, with the result that, after application onto the security document 4, they form the uppermost ply. Alternatively, such layers can also be applied after the application onto the security document 4, for example by means of intaglio printing, pad printing, screen printing or flexographic printing. As a further alternative, such layers can be applied as dry transfer ply by means of a separate transfer process, such as for example by means of hot stamping or UV transfer (cold stamping).

(44) A further area 45 is available for affixing machine-readable data. Here, biometric data of the holder of the security document 4 can be stored, for example. In area 44, machine detectable items of information can be printed on, for example in the form of a 1D or 2D barcode. Particularly advantageously, items of information uniquely identifying the document, such as for example the document number and/or parts of the personal data, are encrypted by means of cryptographic methods and are printed onto the document as machine detectable information. The consistency of the data can then be checked by means of suitable algorithms and thus the authenticity of the entries can be verified.

(45) It is advantageous if the document number is also introduced in the area of the multilayer body 1, i.e. overlapping with the multilayer body 1. The introduction by means of a technique which leads to the multilayer body 1 being altered irreversibly, for example by means of a laser, is particularly advantageous.

(46) Furthermore, partial areas of the metal layers in the first and/or second area can in particular be processed by means of laser radiation after application of the multilayer body 1 onto the security document 4 and thus the metal can be removed. This is suitable, in particular, for introducing an individual identification, such as for example a number. If this processing takes place in the second partial area, the color printing becomes recognizable in the areas freed from metal, which contributes to a further increase in the security. Furthermore, by adapting the laser parameters locally only the metal layer can be removed or at the same time the color layer, with the result that within a number partial areas can be designed colored or not colored, which can be used to further increase the security. Such a processing can already take place in the multilayer body 1 before it is applied onto a substrate or only thereafter.

LIST OF REFERENCE NUMBERS

(47) 1 multilayer body 11 carrier ply 12 transfer ply 13 metal layer 131 first item of optical information 14 protective lacquer 15 partial lacquer layer 151 second item of optical information 16 partial lacquer layer 161 third item of optical information 17 partial lacquer layer 171 fourth item of optical information 18 adhesive layer 2 area of the multilayer body 3 area of the multilayer body 4 security document 41 photograph 42 security feature 43 security feature 44 area of the security document 45 area of the security document