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WO2025078330A1 - Élément multicouche et procédé de production d'un élément multicouche - Google Patents

Élément multicouche et procédé de production d'un élément multicouche Download PDF

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Publication number
WO2025078330A1
WO2025078330A1 PCT/EP2024/078204 EP2024078204W WO2025078330A1 WO 2025078330 A1 WO2025078330 A1 WO 2025078330A1 EP 2024078204 W EP2024078204 W EP 2024078204W WO 2025078330 A1 WO2025078330 A1 WO 2025078330A1
Authority
WO
WIPO (PCT)
Prior art keywords
layer
region
range
multilayer body
color
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
PCT/EP2024/078204
Other languages
German (de)
English (en)
Inventor
Eduard MILOGLYADOV
Sebastian Mader
Harald Walter
Gerrit Hackl
Christian Schulz
Violetta Olszowka
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
OVD Kinegram AG
Leonhard Kurz Stiftung and Co KG
Original Assignee
OVD Kinegram AG
Leonhard Kurz Stiftung and Co KG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from DE102023128034.1A external-priority patent/DE102023128034A1/de
Application filed by OVD Kinegram AG, Leonhard Kurz Stiftung and Co KG filed Critical OVD Kinegram AG
Publication of WO2025078330A1 publication Critical patent/WO2025078330A1/fr
Pending legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B42—BOOKBINDING; ALBUMS; FILES; SPECIAL PRINTED MATTER
    • B42D—BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS
    • B42D25/00—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof
    • B42D25/30—Identification or security features, e.g. for preventing forgery
    • B42D25/324—Reliefs
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B42—BOOKBINDING; ALBUMS; FILES; SPECIAL PRINTED MATTER
    • B42D—BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS
    • B42D25/00—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof
    • B42D25/30—Identification or security features, e.g. for preventing forgery
    • B42D25/328—Diffraction gratings; Holograms
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B42—BOOKBINDING; ALBUMS; FILES; SPECIAL PRINTED MATTER
    • B42D—BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS
    • B42D25/00—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof
    • B42D25/30—Identification or security features, e.g. for preventing forgery
    • B42D25/36—Identification or security features, e.g. for preventing forgery comprising special materials
    • B42D25/373—Metallic materials
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B42—BOOKBINDING; ALBUMS; FILES; SPECIAL PRINTED MATTER
    • B42D—BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS
    • B42D25/00—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof
    • B42D25/40—Manufacture
    • B42D25/405—Marking
    • B42D25/425—Marking by deformation, e.g. embossing
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B42—BOOKBINDING; ALBUMS; FILES; SPECIAL PRINTED MATTER
    • B42D—BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS
    • B42D25/00—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof
    • B42D25/40—Manufacture
    • B42D25/45—Associating two or more layers
    • B42D25/455—Associating two or more layers using heat
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B42—BOOKBINDING; ALBUMS; FILES; SPECIAL PRINTED MATTER
    • B42D—BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS
    • B42D25/00—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof
    • B42D25/40—Manufacture
    • B42D25/45—Associating two or more layers
    • B42D25/46—Associating two or more layers using pressure

Definitions

  • the invention relates to a multilayer body, in particular a security element, and to a method for producing a multilayer body, in particular a security element.
  • the generation of optically variable effects by means of thin-film interference filters is described, for example, in US 3,858,977.
  • a thin-film interference filter is constructed from several layers comprising an interference layer. The incident light is at least partially reflected at the front and back of the interference layer.
  • the thin-film interference filter Due to the small thickness of the interference layer, destructive and/or constructive interference of the reflected light occurs for certain wavelengths in the visible light range, so that the thin-film interference filter has a colored appearance. Because the path length of the light in the interference layer changes depending on the viewing angle and/or illumination angle, the color of the thin-film interference filter changes accordingly, so that such a filter, when illuminated, generates a color dependent on the viewing angle and/or illumination angle as an optically variable effect. In general, there is the problem that thin-film effects can now be imitated by counterfeiters.
  • the invention is based on the object of providing a method for producing a multilayer body, in particular a security element, and a multilayer body, in particular a security element, which enable improved optical effects and also increase forgery security.
  • a multilayer body in particular a security element for securing security documents, preferably hot stamping foil or cold stamping foil or laminating foil or thread foil, having at least two different color-shift effects perceptible to the human eye and/or a sensor
  • the multilayer body comprises a precursor material, wherein the precursor material comprises I) a carrier, at least one release layer, at least one protective lacquer layer, and a replication layer, or II) a carrier, optionally at least one adhesion promoter layer, and a replication layer; and wherein the multilayer body further comprises, in particular applied to the replication layer in the following order, an absorber layer, a dielectric layer with a predetermined thickness, a reflector layer, and at least one primer layer: and that a first asymmetric microstructure in an ⁇ -range for generating a first optically variable effect and a second asymmetric microstructure in a ⁇ -range for generating a second optically variable effect are introduced into the replication layer, and wherein in the multilayer
  • a method for producing a multilayer body in particular a security element for securing security documents, preferably designed as a hot stamping foil or cold stamping foil or laminating foil or thread foil, preferably according to one of claims 1 to 27, having at least two different color-shift effects perceptible to the human eye and/or a sensor, wherein the method comprises the following steps, in particular in the specified order: a) providing a precursor material, wherein the precursor material comprises I) a carrier, at least one release layer, at least one protective lacquer layer, and a replication layer, or II) a carrier, optionally at least one adhesion promoter layer, and a replication layer; b) introducing a first asymmetric microstructure into the replication layer in an ⁇ -range to produce a first optically variable effect and introducing a second asymmetric microstructure into the replication layer in a ⁇ -range to produce a second optically variable effect; c) applying an absorber layer; d) applying a dielectric layer with a
  • the method according to the invention for producing a multilayer body, in particular a security element for securing security documents results in a multilayer body that has increased counterfeit security due to the two different color-shift effects.
  • two different asymmetric microstructures are required in the ⁇ range and the ⁇ range.
  • the asymmetric microstructures in the ⁇ range and the ⁇ range have a sufficiently different angle. Producing these different angles of the asymmetric microstructures requires, in some cases, complex techniques and precise process controls, which make it considerably more difficult for a counterfeiter to produce a copy of the multilayer body according to the invention, in particular the security element.
  • the two different color-shift effects generate a memorable visual impression of the multilayer body, in particular the security element, for the viewer, which differs from conventional security elements.
  • the two color-shift effects are present, complex structures and effects can be created.
  • the two different color-shift effects are in perfect register with other structure-based optical effects, which further increases the hurdle for counterfeiters. Further advantageous embodiments of the invention are described in the subclaims.
  • Color-shift effects based on thin-film interference are characterized in particular by the fact that When illuminated, these generate a color dependent on the viewing angle and/or illumination angle, which is at least partly determined by the occurrence of constructive and/or destructive interference of the light reflected from the top and back of the interference layer.
  • the illumination angle is equal to the viewing angle.
  • the angle ⁇ is the angle between the surface normal and the illumination direction or viewing direction.
  • Multilayer bodies in particular security elements, with color-shift effects preferably have a thin-film structure.
  • this can be a three-layer structure, preferably comprising an absorber layer, a dielectric layer, and a reflector layer.
  • Such a layered structure is often also referred to as a Fabry-Pérot filter or Fabry-Pérot layered structure.
  • the terms multilayer body and applied multilayer body are used herein.
  • Multilayer body generally describes the multilayer body in its initial state.
  • the multilayer body according to variant I in particular in the following order, preferably comprises a carrier, at least one release layer, at least one protective lacquer layer, a replication layer, an absorber layer, a dielectric layer, a reflector layer, optionally further functional layers, and at least one primer.
  • the multilayer body according to variant II), in particular in the following order can comprise a The carrier may optionally comprise at least one adhesion promoter layer, a replication layer, an absorber layer, a dielectric layer, a reflector layer, optionally further functional layers, and at least one primer.
  • the term "applied multilayer body" refers to a multilayer body applied to a substrate.
  • the multilayer body is preferably firmly bonded to the substrate, preferably by means of the primer and/or further adhesive layers.
  • the carrier and optionally the release layer are detached or removed in the multilayer body according to variant I).
  • the applied multilayer body according to variant I) thus preferably comprises, in the following order, at least one protective lacquer layer, a replication layer, an absorber layer, a dielectric layer, a reflector layer, optionally further functional layers, and at least one primer.
  • the carrier can remain in the layer structure even after application.
  • this multilayer body is embedded during the production of the substrate, in particular the paper substrate.
  • the multilayer body has at least one adhesive layer and/or at least one primer on both the feedstock side and the side opposite the feedstock.
  • the embedding of threads or thread foil, in particular of the multilayer body takes place, for example, on cylinder-wire paper machines.
  • the security thread or multilayer body, coated on both sides with adhesive, in particular primers is introduced into a paper pulp during the embedding process and brought to a cylinder wire when paper fiber deposition has occurred there but is not yet complete, so that the thread or thread foil can then is completely enclosed in the finished sheet.
  • This incorporation process is generally known and described, for example, in DE 2408304 A1 (Jung).
  • the described multilayer body, in particular thread film can also be incorporated in the production of laminates.
  • the multilayer body, in particular thread film can be laminated to one of the layers and then incorporated into the actual laminating process. It is also possible for the multilayer body, in particular thread film, to be fed directly into the laminating nip. In this case, one or more webs can be laminated together, or even one or more webs can be processed with one or more melts to form a laminate with a multilayer body, in particular thread film.
  • the thread film is preferably integrated into the substrate of a security document in such a way that at least one window area is present in the substrate, in which the thread film is visible from at least one side of the security document.
  • the thread film is preferably registered, in particular in register, with the at least one window area of the security document, in particular a banknote, integrated into the substrate.
  • the thread film By positioning the thread film in register with the at least one window area of the security document, it is possible for the same optical impression of the thread film, in particular a window film, to be visible in every window area of every security document.
  • the first color-shift effect in the ⁇ range and the second color-shift effect in the ⁇ range to be visible in the same window areas of every security document. This first color-shift effect and second color-shift effect are each generated by asymmetric microstructures.
  • the window area is preferably understood to mean an area of the substrate of the security document in which an opening or a Perforation and/or higher transparency compared to neighboring regions of the substrate.
  • the ⁇ region and the ⁇ region can be arranged differently.
  • the multilayer body can also have a ⁇ region and/or ⁇ region.
  • Each of the ⁇ region and/or ⁇ region and/or ⁇ region and/or ⁇ region can have several subregions, which are preferably arranged separately from one another and/or adjacently and/or overlappingly.
  • the ⁇ region can be formed from two or more subregions, wherein the two or more subregions are arranged at a distance from one another.
  • the ⁇ region is preferably the region with which the first color-shift effect is generated.
  • the multilayer body has the following layers in the ⁇ region, particularly when viewed from the front, in particular in the following order: at least one protective lacquer layer, replication layer, absorber layer, dielectric layer, reflector layer and at least one primer.
  • the first asymmetric microstructure is preferably molded into the replication layer in the ⁇ region.
  • the ⁇ region is the region with which the second color shift effect is generated.
  • the multilayer body has the following layers in the ⁇ region, particularly when viewed from the front, in particular in the following order: at least one protective lacquer layer, replication layer, absorber layer, dielectric layer, reflector layer and at least one primer.
  • the second asymmetric microstructure is preferably molded into the replication layer in the ⁇ region.
  • the ⁇ -region is preferably a region that optically separates the ⁇ -region from the ⁇ -region.
  • the thin-film structure can also be present in the ⁇ -region.
  • the multilayer body has the following layers in the ⁇ -region, particularly when viewed from the front, in particular in the following order: at least one protective lacquer layer, replication layer, absorber layer, dielectric layer, reflector layer, and at least one primer.
  • the ⁇ -region is a region in which the thin-film structure is at least partially structured. As a rule, therefore, no color-shift effect is generated in the ⁇ -region.
  • the multilayer body has the following layers in the ⁇ -region, particularly when viewed from the front, in particular in the following order: at least one protective lacquer layer, replication layer, and at least one primer.
  • View from the front is understood to mean the view of the raw material or the protective lacquer layer and/or the replication layer of the multilayer body, in particular the security element.
  • View from the rear is understood to mean the view of the multilayer body, in particular the security element, from the side opposite the “view from the front,” or, when applied to a surface of a substrate, the view of the side of the substrate facing away from the multilayer body, in particular the security element.
  • “view from the rear” is understood to mean the view of the multilayer body, in particular the security element, from the side opposite the “view from the front.”
  • “Registered” refers to the arrangement of one layer relative to another layer or the structuring of a layer relative to another layer in a manner that is accurate to register.
  • Registered, or register, or register accuracy, or register precision refers to the positioning accuracy of two or more layers relative to one another. The registration accuracy should be within a specified tolerance and as small as possible. At the same time, the registration accuracy of several elements and/or layers relative to one another is an important feature for increasing process reliability.
  • Precise positioning can be achieved, in particular, using sensor-detectable, preferably optically detectable, fiducials or register marks.
  • These fiducials or register marks can either represent specific, separate elements, regions, or layers, or they can themselves be part of the elements, regions, or layers to be positioned.
  • a carrier is preferably understood to be a single-layer or multi-layer film, one or more layers of which comprise, in particular, the following materials or combinations: PET (polyethylene terephthalate), PP (polypropylene), PE (polyethylene), PEN (polyethylene naphthalate), PC (polycarbonate), PVC (polyvinyl chloride), Kapton (polyoxydiphenylene pyromellitimide) or other polyimides, PLA (polylactate), PMMA (polymethyl methacrylate) or ABS (acrylonitrile butadiene styrene).
  • PET polyethylene terephthalate
  • PP polypropylene
  • PE polyethylene
  • PEN polyethylene naphthalate
  • PC polycarbonate
  • PVC polyvinyl chloride
  • Kapton polyoxydiphenylene pyromellitimide
  • PLA polylactate
  • PMMA polymethyl methacrylate
  • ABS acrylonitrile butadiene styrene
  • the layer thickness of the carrier is in particular in a range from 1 ⁇ m to 500 ⁇ m, preferably from 6 ⁇ m to 23 ⁇ m, more preferably from 6 ⁇ m to 16 ⁇ m.
  • the carrier itself can have an adhesion promoter layer. This adhesion promoter layer is applied during the carrier production process.
  • the thickness of the adhesion promoter layer of a carrier supplied by the carrier supplier is preferably in the range of 0.1 ⁇ m to 5 ⁇ m.
  • the primer materials listed below can be used as an adhesion promoter layer.
  • a primer or adhesion promoter layer increases the adhesion between two layers that would otherwise lack sufficient adhesion to each other. For example, this can be the adhesion of the replication layer to the substrate.
  • the primer layer or adhesion promoter layer preferably comprises a material or combination thereof selected from: polyester, polyacrylate, polymethacrylate, polyurethane, polystyrene, polybutyrate, nitrocellulose, polyvinyl chloride, ethylene-vinyl acetate, their copolymers, or similar polymers or mixtures thereof.
  • the primer or adhesion promoter layer can be thermoplastic, chemically crosslinkable, UV-curable, a hybrid variant (thermoplastic and UV-curable or/or otherwise crosslinkable), a cold adhesive/primer, or a self-adhesive primer.
  • the primer or adhesion promoter layer preferably has a thickness in the range from 0.01 ⁇ m to 15 ⁇ m, preferably from 0.1 ⁇ m to 5 ⁇ m.
  • Inorganic materials such as metals, metal oxides, alloys, oxides, or silicates can also serve as adhesion promoters or be part of such a system.
  • the primer or adhesion promoter layer can also contain additives based on organic or inorganic substances that achieve a predetermined effect on the processing properties, for example when applying a layer of the multilayer body in the above method for producing a multilayer body or when using the multilayer body itself.
  • the proportion of additives in the total coating of the primer or adhesion promoter layer is usually between 0% and 10%, preferably between 0% and 5%, more preferably between 0.01% and 3%.
  • fillers can also be part of the formulation of a primer or adhesion promoter layer. This preferably includes all other materials added to a system, especially a polymer-based system, such as silica, pigments, dyes, tracers, especially taggants, and/or similar materials.
  • the proportion of fillers in the total coating of the primer or adhesion promoter layer is usually between 0% and 80%.
  • primers or adhesion promoter layers can be formulated in such a way that they remain tacky to liquid even after the solvent has evaporated and/or before complete curing. This is particularly advantageous when two substrates are to be bonded together over a large area, as is typically the case in a laminating process.
  • the increased adhesion between the carrier and the replication layer can optionally also be achieved through surface-activating processes such as corona treatment or plasma treatment. These can also be used in combination with a primer or adhesion promoter layer.
  • the release layer ensures, in particular, that the layers of the multilayer body, especially when used as an embossing foil, can be separated from the carrier as transfer layers without causing damage.
  • the release layer preferably comprises a material or combination of materials selected from: waxes, polyethylene (PE), polypropylene (PP), cellulose derivatives, and/or poly(organo)siloxanes.
  • the aforementioned waxes can be natural waxes, synthetic waxes, or combinations thereof. Examples of such waxes are carnauba waxes. Examples of such cellulose derivatives are cellulose acetate (CA), cellulose nitrate (CN), cellulose acetate butyrate (CAB), or mixtures thereof.
  • Examples of such poly(organo)siloxanes are silicone binders, polysiloxane binders, or mixtures thereof.
  • the release layer has preferably has a layer thickness in the range of 1 nm to 500 nm, in particular between 5 nm and 250 nm, preferably between 10 nm and 250 nm.
  • the protective lacquer layer provides protection against mechanical or physical-chemical stresses.
  • the carrier itself can function as a protective lacquer layer.
  • the carrier is removed after application of the multilayer body.
  • a protective lacquer layer is preferably provided, which, after removal of the carrier, represents the outermost layer of the multilayer body in the applied state.
  • the protective lacquer layer is preferably a layer made of PMMA, PVC, melamines, and/or acrylates.
  • the protective lacquer layer can also be made of a radiation-curing dual-cure lacquer.
  • This dual-cure lacquer can be thermally pre-crosslinked in a first step during and/or after application in liquid form.
  • the dual-cure coating is post-crosslinked radically, particularly via high-energy radiation, preferably UV radiation.
  • Dual-cure coatings of this type can consist of various polymers or oligomers containing unsaturated acrylate or methacrylate groups. These functional groups can be radically crosslinked with one another, particularly in the second step.
  • these polymers or oligomers also contain at least two or more alcohol groups. These alcohol groups can be crosslinked with multifunctional isocyanates or melamine-formaldehyde resins.
  • the melamine crosslinkers can be fully etherified versions, imino types, or benzoguanamine types.
  • the protective coating layer preferably has a layer thickness in the range of 50 nm to 30 ⁇ m, preferably from 1 ⁇ m to 5 ⁇ m.
  • the protective coating layer can be produced or applied by gravure printing, flexographic printing, screen printing, inkjet printing, or by means of a slot nozzle and/or by vapor deposition, in particular by means of physical vapor deposition (PVD), chemical vapor deposition (CVD), and/or sputtering.
  • a replication layer is preferably understood here to be a special, functional layer into which structures, preferably optically variable structures, are introduced and/or fixed, in particular by means of thermal replication and/or UV replication.
  • a hybrid replication layer this is, for example, replicated thermally and then cured by means of radiation, for example by means of UV radiation and/or at least one electron beam.
  • this is preferably replicated at room temperature and simultaneously cured by means of radiation, for example by means of UV radiation and/or at least one electron beam.
  • the varnish it is possible for the varnish to become warm during UV replication.
  • the replication layer it is possible for the replication layer to have a layer thickness in the range of 0.1 ⁇ m to 30 ⁇ m, in particular in the range of 0.5 ⁇ m to 10 ⁇ m.
  • the reflector layer comprises a material or combination of materials selected from: aluminum, chromium, copper, tin, silver, indium, nickel, iron, gold and/or an alloy of such metals.
  • the reflector layer is thus a metal layer or metallization.
  • the reflector layer is preferably applied or produced by vacuum vapor deposition.
  • the vapor deposition or application of the reflector layer can be carried out over the entire surface or optionally retained over the entire surface, or it can be structured or partially removed using demetallization processes such as etching, lift-off, or photolithography, thus remaining only partially present.
  • the reflector layer is applied in the ⁇ and ⁇ ranges, in particular the ⁇ range, more preferably over the entire surface.
  • the reflector layer is preferably opaque.
  • OD optical density
  • the reflector layer has a layer thickness in the range of 10 nm to 100 nm.
  • the reflector layer can also consist of a printed layer, in particular a printed layer of metallic pigments in a binder. These printed metallic pigments can be applied over the entire surface or partially. In this case, the thickness of the reflector layer ranges from 1 ⁇ m to 3 ⁇ m. It is also possible to produce the reflector layer from a lacquer containing electrically conductive metallic pigments, in particular by printing and/or pouring it on.
  • the reflector layer is present in the ⁇ and ⁇ ranges, in particular in the ⁇ and/or ⁇ ranges. If the reflector layer is present in the ⁇ range, it is also preferably provided that the absorber layer is not present in the ⁇ range. This ensures that there is no thin-film buildup in the ⁇ range and thus, no color-shift effect is present. The ⁇ range can then be perceived by an observer as a contrast or clear optical demarcation from the ⁇ range and/or ⁇ range.
  • the reflector layer can be designed like an absorber layer.
  • the reflector layer is semi-transparent, making the entire thin-film structure semi-transparent and thus exhibiting a color impression or a color-shift effect even in transmitted light.
  • the reflector layer is designed as an absorber layer
  • the absorber layer is a semi-transparent layer that reflects a certain proportion R of the incident light, while the remainder of the light passes through this layer or is partially absorbed.
  • the absorber layer preferably has an optical density OD in the range of 0.15 to 0.7.
  • the absorber layer is preferably a metal layer.
  • the absorber layer comprises a material or combination of materials selected from: chromium, iron, tin, gold, copper, aluminum, titanium, silicon, and/or alloys thereof.
  • Compounds such as nickel-chromium-iron or rarer metals such as vanadium, palladium, or molybdenum can also be used as the material of the absorber layer.
  • suitable materials include nickel, cobalt, tungsten, niobium, aluminum, and metal compounds such as metal fluorides, oxides, sulfides, nitrides, and carbides.
  • the absorber layer has a layer thickness in the range of 3 nm to 20 nm. It is preferably possible for the absorber layer to be present in the ⁇ and ⁇ ranges, in particular in the ⁇ and/or ⁇ ranges. In particular, if the absorber layer is present in the ⁇ range, the dielectric layer and/or the reflector layer are not present in the ⁇ range.
  • the dielectric layer preferably functions as a spacer layer in the thin-film structure.
  • the thickness d and the material of the dielectric layer significantly determine the generated color of the thin-film structure, in particular the general color-shift effect.
  • the predetermined thickness of the dielectric layer is in the range from 0.05 ⁇ m to 1.0 ⁇ m, in particular from 0.1 ⁇ m to 0.80 ⁇ m, in particular wherein the predetermined thickness has a variance of less than 10%, preferably less than 3%, of the thickness.
  • the dielectric layer comprises a material or a combination of materials selected from: MgF2, SiO2, SiOx, ZnS, Al2O3, TiO2, Nb2O5 and/or MgO, and/or polymers.
  • the dielectric layer is preferably applied using vacuum coating technologies. This is preferably physical vapor deposition (PVD) or chemical vapor deposition (CVD).
  • the dielectric layer using a printing process, with the coatings used comprising a binder or combination of binders selected from: polyacrylates, polyurethanes, epoxies, polyesters, polyvinyl chlorides, rubber polymers, ethylene-acrylic acid copolymers, ethylene-vinyl acetates, polyvinyl acetates, styrene block copolymers, phenol-formaldehyde resins, melamines, alkenes, allyl ethers, vinyl acetate, alkyl vinyl ethers, conjugated dienes, styrene, and acrylates.
  • binders selected from: polyacrylates, polyurethanes, epoxies, polyesters, polyvinyl chlorides, rubber polymers, ethylene-acrylic acid copolymers, ethylene-vinyl acetates, polyvinyl acetates, styrene block copolymers, phenol-formaldehyde
  • the dielectric layer is preferably transparent or translucent, the latter being achieved using the fillers described above. It may also be possible to apply the dielectric layer using a printing process. Suitable printing processes for this purpose include gravure printing, flexographic printing, offset printing, slot die casting, or curtain coating. The use of a printed, polymer-based dielectric layer also offers the advantage that it can be provided with a translucent intrinsic color via fillers, which can influence the color shift effect that occurs.
  • the dielectric layer has an optical thickness n ⁇ d in the range from 70 nm to 1200 nm, in particular from 500 nm to 1000 nm, preferably from 600 nm to 1000 nm, in particular where the optical thickness is determined from the product of the predetermined thickness or material thickness d of the dielectric layer and the refractive index n of the dielectric layer.
  • the at least one primer is preferably an adhesive that preferably increases or improves adhesion to other layers, for example, to the substrate to which the multilayer body is to be applied.
  • the at least one primer used can preferably comprise one or more adhesives selected from: single-layer adhesive, multi-layer adhesive, water-based adhesive, solvent-based adhesive, solvent-free adhesive, radiation-curing adhesive, thermally activated adhesive, thermally curable adhesive, or combinations thereof. It is particularly provided that the at least one primer is applied by means of a printing process and/or by pouring and/or by doctoring. Furthermore, it is advantageous if the at least one primer is applied at least partially, preferably over the entire surface.
  • the layer thickness of the individual adhesive layers within the primer is between 0.01 ⁇ m and 8 ⁇ m, preferably between 0.05 ⁇ m and 5 ⁇ m.
  • the adhesive layer or layers comprise at least one binder selected from: polyacrylates, polyurethanes, epoxies, polyesters, polyvinyl chlorides, rubber polymers, ethylene-acrylic acid copolymers, ethylene-vinyl acetates, polyvinyl acetates, styrene block copolymers, phenol-formaldehyde resin adhesives, melamines, alkenes, allyl ethers, vinyl acetate, alkyl vinyl ethers, conjugated dienes, styrene, acrylates, and/or combinations thereof.
  • binder selected from: polyacrylates, polyurethanes, epoxies, polyesters, polyvinyl chlorides, rubber polymers, ethylene-acrylic acid copolymers, ethylene-vinyl acetates, polyvinyl acetates, styrene block copolymers, phenol-formaldehyde resin adhesives, melamines, alken
  • the varnish from which the adhesive layer is produced by an application process comprises at least one solvent selected from: water, aliphatic (gasoline) hydrocarbons, cycloaliphatic hydrocarbons, terpene hydrocarbons, aromatic (benzene) hydrocarbons, chlorinated hydrocarbons, esters, ketones, alcohols, glycols, glycol ethers, glycol ether acetates, and/or combinations thereof.
  • This solvent or The solvent mixture is largely removed during the application process.
  • the at least one primer or adhesive may contain at least one additive selected from: hardeners, crosslinkers, photoinitiators, fillers, stabilizers, inhibitors, corrosion inhibitors, additives such as flow control additives, defoamers, deaerators, dispersing additives, wetting agents, lubricants, matting agents, rheology additives, pigments, anti-corrosive pigments, dyes, waxes, and/or combinations thereof.
  • additives such as flow control additives, defoamers, deaerators, dispersing additives, wetting agents, lubricants, matting agents, rheology additives, pigments, anti-corrosive pigments, dyes, waxes, and/or combinations thereof.
  • a thermally activated adhesive and/or an adhesive containing thermoplastic and/or UV-based raw materials has a solids content in the range of 10% to 100%, preferably 15% to 35%. This allows for high-quality application on the painting machine. It is also preferred that the adhesive has a non-sticky surface after drying, especially at room temperature. It is also advantageous if the raw materials for the adhesive are selected such that the processing temperature during production of the multilayer body is always above the glass transition temperature and below the melting point of the adhesive.
  • a multilayer adhesive layer offers the particular advantage that excellent adhesion can be achieved even between very demanding surfaces.
  • a multilayer structure enables primer systems that can meet a wide range of chemical and physical resistance requirements. Chemical resistance refers to the resistance of the adhesive layer to the effects of chemicals.
  • the composition of the adhesive layers is preferably selected so that they exhibit sufficient resistance to predefined chemicals. Furthermore, it is advantageously provided that, in multilayer adhesives, intermediate adhesion of the individual layers to one another is ensured. This is achieved by a suitable selection of the adhesive components.
  • the first color-shift effect, in particular in the ⁇ range to generate a first color dependent on the viewing angle and/or exposure angle based on interference upon exposure
  • the second color-shift effect, in particular in the ⁇ range to generate a second color dependent on the viewing angle and/or exposure angle based on interference upon exposure.
  • the first color in particular the first color-shift effect
  • the first color is generated based on a superposition of the first optically variable effect with the general color-shift effect.
  • the first color, in particular the second color-shift effect is generated based on a superposition of the second optically variable effect with the general color-shift effect.
  • the total area of the ⁇ -region is at least 4 mm 2 , more preferably at least 6 mm 2 , particularly preferably at least 9 mm 2 , wherein in particular the extent of the individual surfaces of the ⁇ -region in both the x-direction and the y-direction is at least 1 mm, preferably at least 2 mm.
  • the total area of the ⁇ -region is at least 4 mm 2 , more preferably at least 6 mm 2 , particularly preferably at least 9 mm 2 , whereby in particular the extent of the individual areas of the ⁇ -region both in in both the x-direction and the y-direction, is at least 1 mm each, preferably at least 2 mm each. This ensures that the different color-shift effects are clearly perceptible to the human eye.
  • the first asymmetric microstructure differs from the second asymmetric microstructure, in particular wherein the structural parameters of the first asymmetric microstructure differ from the structural parameters of the second asymmetric microstructure.
  • the first asymmetric microstructure and/or the second asymmetric microstructure may have structures selected from: blazed gratings, micromirrors, microfacets, microprism structures, and/or Fresnel-like microstructures.
  • the first asymmetric microstructure and/or the second asymmetric microstructure to have an average lateral extent of at least 3 ⁇ m, in particular at least 5 ⁇ m.
  • the grating lines of the first asymmetric microstructure and/or the second asymmetric microstructure are configured to be linear, curved, or corrugated.
  • the first asymmetric microstructure and/or the second asymmetric microstructure each have varying structural parameters, in particular wherein the structural width extending in the x-direction and/or the structural width extending in the y-direction and/or the structural depth are varied.
  • the structural width can be varied in the x-direction and/or y-direction and the structural depth to be constant.
  • the structural depth can vary and the structural width in the x-direction and/or y-direction is constant.
  • both the structure width in the x-direction and y-direction and the structure depth can be varied.
  • the first asymmetric microstructure deflects the incident light at a first defined angle when light is incident perpendicularly onto the multilayer body.
  • the first asymmetric microstructures deflect at least 60% of the incident light, preferably at least 75% of the incident light, particularly preferably at least 90% of the incident light, into a first angular range in the range from -40° to -6° and/or +6° to 40°, preferably in the range from -35° to -7° and/or +7° to +35°, further preferably in the range from -30° to -8° and/or +8° to 30°, particularly preferably in the range from -20° to -8° and/or +8° to +20°.
  • the greater the angle change the greater the color change compared to the color impression of the multilayer body, especially the multilayer structure, upon direct reflection on a mirror surface.
  • the resulting color impression or the first color shift effect in the ⁇ range is therefore determined by the mean or integrated angle of the deflected light. Even with a deflection of at least 60% of the incident light into the angular ranges defined above, the color impression can change noticeably for the observer. Furthermore, it can also be provided that the second asymmetric microstructure deflects this incident light at a second defined angle when light is incident perpendicularly onto the multilayer body.
  • the second asymmetric microstructure deflects at least 60% of the incident light, preferably at least 75% of the incident light, particularly preferably at least 90% of the incident light, in a second angular range in the range from -5° to 0° and/or 0° to +5°, preferably in the range from -3° to 0° and/or 0° to +3°. Due to the small angular change, the color impression of the ⁇ -region essentially corresponds to that of the multilayer structure upon direct reflection on a mirror surface. For In the special case of a mirror surface, deflection 0°, the second color-shift effect corresponds exactly to the general color-shift effect caused by the thin-film structure alone.
  • the first asymmetric microstructure and/or the second asymmetric microstructure are introduced by means of thermal replication or UV replication.
  • further structures in particular microstructures and/or nanostructures, to be introduced into the replication layer in a ⁇ -range and/or ⁇ -range by means of thermal replication or UV replication.
  • the color space is represented by a sphere, which is defined by the three axes of brightness L, red-green axis a, and yellow-blue axis b.
  • L 0 to black
  • L 50 to the achromatic point.
  • Lp,v is the brightness
  • ap,v the color value on the red-green axis
  • bp,v the color value on the yellow-blue axis of the two color coordinates.
  • the color deviation ⁇ Epv between two color coordinates is calculated as follows: where, in particular, " ⁇ L” is the brightness difference, the value " ⁇ a” is the color difference on the red-green axis, and “ ⁇ b” is the color difference on the yellow-blue axis of two colors. In general, the following applies in particular: the smaller the value ⁇ E, the smaller the color differences.
  • a color difference perceptible to the human eye preferably has a value for ⁇ E of at least 5 and more preferably of at least 10.
  • the layer thickness of the absorber layer in the ⁇ and ⁇ ranges, as well as the layer thickness of the dielectric layer in the ⁇ and ⁇ ranges, and the layer thickness of the reflector layer in the ⁇ and ⁇ ranges are homogeneous or consistent.
  • the absorber layer in step c), the dielectric layer in step d), and the reflector layer in step e) are each applied over the entire surface, in particular in the ⁇ -range and ⁇ -range, with a constant or homogeneous layer thickness. This ensures that the general color-shift effect conveys the same color impression in both the ⁇ -range and the ⁇ -range.
  • the absorber layer in step c), the dielectric layer in step d), and the reflector layer in step e) may be applied over the entire surface, particularly also in the ⁇ -range, with a consistent or homogeneous layer thickness. This ensures that the general color-shift effect in the ⁇ -range, the ⁇ -range, and the ⁇ -range conveys the same color impression. In the ⁇ -range and the ⁇ -range, this general color impression is superimposed with the optically variable effects of the first asymmetric microstructure and the second asymmetric microstructure to generate two different color-shift effects.
  • the multilayer body has a ⁇ -range in which the absorber layer and/or the dielectric layer and/or the reflector layer are not present.
  • the absorber layer, the dielectric layer, and the reflector layer are not present in the ⁇ -range.
  • the method further includes the following steps: - at least partially applying a washable lift-off resist, preferably in a ⁇ range, in particular by printing, preferably in register with the first asymmetric microstructure and/or second asymmetric microstructure, wherein the step is performed after step b) and before step c); - removing the lift-off resist with a solvent in a washing process to remove the absorber layer, the dielectric layer, and the reflector layer, in particular in the ⁇ range, wherein the step is performed after step e) and before step f).
  • This provides a multilayer body, in particular a security element, that appears translucent and transparent in the ⁇ range.
  • the reflector layer is structured or removed in the ⁇ range.
  • step e) and before step f) - applying a photoresist layer, in particular applying the photoresist layer over the entire surface; - Exposing and developing the photoresist layer with an exposure mask, preferably in a ⁇ -range, in particular registering the first asymmetric microstructure and/or second asymmetric microstructure; - Removing the reflector layer in the ⁇ -range, in particular by etching, and removing the photoresist layer.
  • This provides a multilayer body that appears light gray to the observer in the ⁇ -range in transmitted light.
  • the observer may perceive a slight thin-film effect in the ⁇ -range. which, however, is not as intense and strong as the color-shift effects in the ⁇ -range and/or ⁇ -range.
  • This slight thin-film effect is particularly visible when the refractive index of the dielectric layer and the refractive index of the at least one primer, in particular the adhesive layer, have a sufficient difference.
  • step e) and before step f) - applying an etching resist layer such that the etching resist layer is not present in a ⁇ -range, preferably in register with the first asymmetric microstructure and/or second asymmetric microstructure; - removing the reflector layer in the ⁇ -range, in particular by etching; - optionally washing or removing the etching resist layer.
  • the etching resist can preferably remain in the layer structure of the multilayer body, in particular of the security element. This also provides a multilayer body that appears light gray to the observer in the ⁇ range in transmitted light.
  • the observer may perceive a slight thin-film effect in the ⁇ range, which, however, is not as intense and strong as the color-shift effects in the ⁇ range and/or ⁇ range.
  • This slight thin-film effect is particularly visible when the refractive index of the dielectric layer and the refractive index of the at least one primer, in particular the adhesive layer, exhibit a sufficient difference. It may also be possible for both the reflector layer and the dielectric layer to be structured or removed in the ⁇ range.
  • the method further includes the following steps: - at least partially applying a washable lift-off varnish, preferably in a ⁇ -range, in particular by printing, preferably in register with the first asymmetric microstructure and/or second asymmetric microstructure, wherein the step is performed after step c) and before step d); - removing the lift-off varnish with a solvent in a washing process to remove the dielectric layer and the reflector layer, in particular in the ⁇ -range, wherein the step is performed after step e) and before step f).
  • This provides a multilayer body that, in incident light, presents a grayish, metallic appearance to the observer in the ⁇ -range. In transmitted light, the ⁇ -range appears light gray to the observer.
  • the absorber layer in the ⁇ -range may also be structured or removed.
  • the following further steps are carried out in the method: - at least partial application of a washable lift-off varnish, preferably in a ⁇ range, in particular by means of printing, preferably registered to the first asymmetric microstructure and/or second asymmetric microstructure, wherein the step is carried out after step b) and before step c); - removal of the lift-off varnish with a solvent in a washing process in order to remove the absorber layer, in particular in the ⁇ range, wherein the step is carried out after step c) and before step d).
  • a washable lift-off varnish preferably in a ⁇ range, in particular by means of printing, preferably matched to the first asymmetric microstructure and/or second asymmetric microstructure, wherein the step is performed after step b) and before step c); - removing the lift-off varnish with a solvent in a washing process to remove the absorber layer 16 and the dielectric layer 17, in particular in the ⁇ range, wherein the step is performed after step d) and before step e).
  • This preferably provides a multilayer body that allows an observer to see a silver layer in the ⁇ range in reflected light, which layer may be overlaid with structural effects.
  • the thin-film structure is/is completely or at least partially removed or structured in the ⁇ range, generally no color-shift effect and/or optically variable effect is generated in the ⁇ range. Rather, it may be possible that, if there is no layer of the thin-film structure, the at least one primer directly borders the replication layer in the ⁇ range.
  • the at least one primer and the replication layer have a similar refractive index, no optically variable effect is generated in the ⁇ range by the introduced structures. Furthermore, it can be provided, in particular, that the ⁇ range is completely enclosed by the ⁇ range and/or ⁇ range and/or ⁇ range. It may also be possible for the ⁇ range to be arranged such that the ⁇ - The region is completely enclosed by the ⁇ region and/or ⁇ region and/or ⁇ region. Furthermore, it can be provided that the ⁇ region completely encloses the ⁇ region and/or ⁇ region and/or ⁇ region. It is also possible for the ⁇ region to be arranged such that the ⁇ region completely encloses the ⁇ region and/or ⁇ region and/or ⁇ region.
  • the multilayer body has a ⁇ region, with the ⁇ region being arranged between the ⁇ region and the ⁇ region, so that the ⁇ region optically separates the ⁇ region from the ⁇ region, or vice versa.
  • further structures in particular those different from the first asymmetric microstructure and/or the second asymmetric microstructure, to be introduced into the ⁇ -range in the replication layer, preferably wherein the further structures comprise microstructures and/or nanostructures.
  • the structures in the ⁇ -range can be subwavelength gratings, in particular subwavelength cross gratings, with a grating period between 150 nm and 500 nm, preferably with a grating period between 200 nm and 350 nm.
  • These further structures can generate an additional optically variable effect that differs from the first optically variable effect and/or the second optically variable effect.
  • these further structures overlay the general color-shift effect caused by the underlying thin-film structure and thus generate a further color-shift effect that differs from the first color-shift effect and the second color-shift effect.
  • the ⁇ -range may also preferably be possible for the ⁇ -range to be designed as a mirror surface.
  • the ⁇ -region is/will only be configured as a mirror surface if the second asymmetric microstructure is not configured as a mirror surface.
  • the ⁇ - A color-shift effect is created in the replication layer in step b), which essentially corresponds to the general color-shift effect.
  • further structures in particular those different from the first asymmetric microstructure and/or the second asymmetric microstructure, to be introduced into a ⁇ -region in the replication layer, preferably wherein the further structures comprise microstructures and/or nanostructures, and/or for the ⁇ -region in the replication layer to be configured as a mirror surface.
  • the ⁇ -region is arranged between the ⁇ -region and the ⁇ -region, so that the ⁇ -region optically separates the ⁇ -region from the ⁇ -region. It is preferably possible for the ⁇ -region and the ⁇ -region to be arranged directly adjacent to one another, spaced apart, partially overlapping, and/or enclosing one another. Furthermore, it may be possible for the ⁇ -region to enclose the ⁇ -region, or vice versa.
  • the ⁇ -region and/or the ⁇ -region and/or the ⁇ -region and/or the ⁇ -region is configured as a display element or has a display element selected from: a graphically designed outline, a figurative representation, an image, a single image, a pattern, a continuous pattern, a motif, a symbol, a logo, a portrait, a grid, an alphanumeric character, a text, and/or combinations thereof.
  • the ⁇ -region is configured in the form of a display element as listed above, and at the same time, the ⁇ -region forms the background of the display element. Furthermore, the ⁇ -region can form the background of the entire multilayer body.
  • the multilayer body is designed as a thread foil, since with this type of multilayer body, the area available for the color-shift effects is very small. It is preferably provided that such a thread foil has a width in the range from 1 mm to 25 mm, in particular from 3 mm to 10 mm. Due to the two color-shift effects in the ⁇ and ⁇ ranges, which are different for the human eye, the display elements can be perceived more quickly and better. Furthermore, it can be provided that the multilayer body has at least one functional layer, in particular wherein the at least one functional layer is arranged between the at least one primer and the reflector layer.
  • step g) Applying at least one functional layer.
  • a functional layer can be understood, for example, as a color layer, a metal layer, and/or a decorative layer. This at least one functional layer then creates a further optical color impression that is perceptible to the viewer.
  • the multilayer body has at least one adhesive layer on one or both of its outer sides, in particular the front and/or back.
  • the multilayer body is provided with at least one adhesive layer on one or both of its outer sides, in particular the front and/or back, in particular by means of gravure printing, flexographic printing, screen printing, inkjet printing, or by means of a slot nozzle and/or By vapor deposition, in particular by physical vapor deposition (PVD), chemical vapor deposition (CVD), and/or sputtering.
  • PVD physical vapor deposition
  • CVD chemical vapor deposition
  • sputtering sputtering.
  • the method for producing a multilayer body, as well as the multilayer body itself provides a multilayer body, in particular a security element, which can be applied to a substrate, for example, a security document or a paper banknote or a polymer banknote, by embossing or lamination.
  • the multilayer body, in particular the security element can also be embedded in the form of a thread film into the substrate of a security document, e.g., into the substrate of a paper banknote.
  • the multilayer body, in particular the security element with its two different color-shift effects, offers the advantage over conventional security elements with a simple thin-film structure that the viewer can perceive a double color-shift effect, whereas only simple color-shift effects are realized in the prior art.
  • the two different color-shift effects increase security against counterfeiting, since to produce these two different color-shift effects, various asymmetric microstructures must be introduced into the replication layer, which cannot be easily imitated by counterfeiters.
  • the multilayer body in particular the security element, can be designed as a hot stamping foil, cold stamping foil, or laminating foil and is therefore versatile.
  • the invention is explained below using several exemplary embodiments with the aid of the accompanying drawings. The exemplary embodiments shown are therefore not to be understood as limiting.
  • Fig. 0a schematically shows the functional principle of the thin-film structure using a schematic multilayer body
  • Fig. 0b schematically shows the functional principle of the thin-film structure, including the resulting path difference
  • Fig. 1 schematically shows the process steps of a method for producing a multilayer body
  • Fig. 2 schematically shows the process steps of a method for producing a multilayer body
  • FIG. 3 schematically shows the process steps a) and b) for producing a multilayer body in detail
  • Fig. 4a schematically shows the process steps c) to f) for producing a multilayer body in detail
  • Fig. 4b schematically shows the process steps c) to f) for producing a multilayer body in detail
  • Figs. 5a and b schematically show a multilayer body, in particular produced using a method according to Fig. 1 or Figs. 3 and 4, in a plan view (top) and a sectional view AA' (bottom), in particular wherein the multilayer body is applied to a substrate
  • Fig. 4a schematically shows the process steps c) to f) for producing a multilayer body in detail
  • Fig. 4b schematically shows the process steps c) to f) for producing a multilayer body in detail
  • Figs. 5a and b schematically show a multilayer body, in particular produced using a method according to Fig. 1 or Figs.
  • FIG. 6a, b schematically show a multilayer body, in particular produced by a method according to Figure 1 or Figures 3 and 4 in a plan view (top) and in a sectional view B-B' (bottom), in particular wherein the multilayer body is applied to a substrate;
  • Figure 7 schematically shows a multilayer body, in particular produced using a method according to Figure 1, in a plan view (top) and in a sectional view C-C' (bottom), in particular wherein the multilayer body is applied to a substrate;
  • Figure 8 schematically shows a multilayer body, in particular produced using a method according to Figure 1, in a plan view (top) and in a sectional view D-D' (bottom), in particular wherein the multilayer body is applied to a substrate;
  • Figure 9 schematically shows the process steps for structuring the reflector layer in the ⁇ range using photoresist;
  • Figure 10 schematically shows a multilayer body in a sectional view with the ⁇ range and the ⁇ range;
  • the figures illustrate various examples of embodiments of the invention. Identical or equivalent components have been provided with the same reference symbols. Where the embodiments illustrated in the figures have common features, these common features have been omitted to avoid repetition. The respective differences between the embodiments are described in relation to the respective figures. It goes without saying that a person skilled in the art can modify individual embodiments or combine individual features of these embodiments within the scope of the claims.
  • the ⁇ region is identified by the reference symbol ⁇ , the ⁇ region by the reference symbol ⁇ , the ⁇ region by the reference symbol ⁇ , and the ⁇ region by the reference symbol ⁇ .
  • the following reference symbols ⁇ , ⁇ , ⁇ , and ⁇ for the respective regions are omitted in the following description of the figures.
  • multilayer bodies 10 in particular security elements, with a thin-film effect have a thin-film structure.
  • This layer structure is often also referred to as a Fabry-Perot filter or Fabry-Perot layer structure.
  • Figure 0a shows a schematic sectional view of a multilayer body 10 applied to a substrate 30.
  • This multilayer body 10 comprises, from top to bottom, the following layers: protective lacquer layer 14, replication layer 15, absorber layer 16, dielectric layer 17 with a predetermined thickness d, reflector layer 18, and a primer 19. Also shown is directed illumination, indicated by the lamp, at an angle of incidence ⁇ . The incident light rays pass through the absorber layer 16 and the dielectric layer 17, are reflected by the reflector layer 18, and then the reflected light beam passes through the dielectric layer 17 and the absorber layer 16 again. At an angle of reflection ⁇ , the observer thus perceives a color effect generated by the thin-film structure. For simplicity, partial reflection at the absorber layer 16 and light refraction have been neglected in Figure 0a.
  • Figure 0b schematically shows the thin-film structure from Figure 0a, explaining the path difference ⁇ s between the partial beam reflected by the absorber layer 16 and the partial beam reflected by the reflector layer 18.
  • Figure 0b takes light refraction into account.
  • multiple reflections occur within the thin-film structure. While the first partial beam only travels the distance A-P, the second partial beam must travel the distances A-B and B-C, including the optical path through the absorber layer 16.
  • the path difference is therefore calculated according to formula 1a), since the distances AB and BC are equal in magnitude.
  • n is the refractive index of the spacer layer material: Formula 1a) is preferably an approximation.
  • FIG. 1 schematically shows a method for producing a multilayer body 10, in particular a security element for securing security documents, preferably designed as a hot stamping foil, cold stamping foil, or laminating foil, having at least two different color shift effects perceptible to the human eye and/or a sensor.
  • the method according to Figure 1 involves the following steps: a) Providing a precursor material 1, 11, wherein the precursor material 11 has a carrier 12, at least one release layer 13, at least one protective lacquer layer 14, and a replication layer 15. or II) a carrier 12, optionally comprising at least one adhesion promoter layer and a replication layer 15; b) introducing a first asymmetric microstructure into the replication layer 2, 15 in an ⁇ region to produce a first optically variable effect and introducing a second asymmetric microstructure into the replication layer 2, 15 in a ⁇ region to produce a second optically variable effect; c) applying an absorber layer 3, 16; d) applying a dielectric layer 4, 17 with a predetermined thickness d; e) applying a reflector layer 5, 18; f) applying at least one primer 6, 19.
  • the method to carry out the following steps: a) providing a precursor material 1, 11, wherein the precursor material 11 I) has a carrier 12, at least one release layer 13, at least one protective lacquer layer 14 and a replication layer 15 or II) has a carrier 12, optionally at least one adhesion promoter layer and a replication layer 15; b) introducing a first asymmetric microstructure into the replication layer 2, 15 in an ⁇ -region to produce a first optically variable effect and introducing a second asymmetric microstructure into the replication layer 2, 15 in a ⁇ -region to produce a second optically variable effect; e) applying a reflector layer 5, 18; d) applying a dielectric layer 4, 17 with a predetermined thickness d; c) Applying an absorber layer 3, 16; f) Applying at least one primer 6, 19.
  • the steps according to variant I) are carried out to prepare the precursor material 1, 11 in step a).
  • the steps according to variant II) are carried out to prepare the precursor material 1, 11 in step a).
  • a general color shift effect is generated by the absorber layer 16, the dielectric layer 17 and the reflector layer 18, which is superimposed with the first optically variable effect in the ⁇ range and with the second optically variable effect in the ⁇ range, so that a first color shift effect is generated in the ⁇ range and a second color shift effect is generated in the ⁇ range, wherein the first color shift effect differs from the second color shift effect.
  • Figure 2 schematically shows the method steps of a method for producing a multi-layer body 10. The method is essentially the method according to Figure 1, but with the difference that in the method the following step is carried out after step e) and before step f): g) Applying at least one functional layer.
  • the at least one functional layer can be, for example, a further replication layer 15 with further, in particular optically effective, structures. Furthermore, a functional layer can also be understood as a colored layer or decorative layer.
  • Figure 3 schematically shows the process steps a) and b) for producing a multilayer body 10 in detail. This particularly illustrates the provision or production of a precursor material 11, in particular as a hot stamping foil.
  • Figure 3 shows arrows with numbers that are intended to delimit the individual process steps. The numbering in the arrows refers exclusively to the sequence of the process steps and should not be confused with the general reference symbols.
  • a carrier 12 is provided in the first step.
  • a carrier 12 is preferably understood to be a single-layer or multi-layer film, one or more layers of which comprise, in particular, the following materials or combinations: PET (polyethylene terephthalate), PP (polypropylene), PE (polyethylene), PEN (polyethylene naphthalate), PC (polycarbonate), PVC (polyvinyl chloride), Kapton (polyoxydiphenylene pyromellitimide) or other polyimides, PLA (polylactate), PMMA (polymethyl methacrylate), or ABS (acrylonitrile butadiene styrene).
  • PET polyethylene terephthalate
  • PP polypropylene
  • PE polyethylene
  • PEN polyethylene naphthalate
  • PC polycarbonate
  • PVC polyvinyl chloride
  • Kapton polyoxydiphenylene pyromellitimide
  • PLA polylactate
  • PMMA polymethyl methacrylate
  • ABS acrylonitrile butadiene styrene
  • the carrier 12 When using the multilayer body 10 as a stamping foil, in particular hot stamping foil or cold stamping foil, the carrier 12 is peeled off after the application of the multilayer body 10 to a substrate 30.
  • a release layer 13 is present, which promotes the detachment of the carrier 12.
  • the application of a release layer 13 is shown in the second step of Figure 3.
  • the third step of Figure 3 shows the application of at least one protective lacquer layer 14.
  • the protective lacquer layer 14 offers protection against mechanical or physico-chemical stresses.
  • the carrier 12 itself can function as a protective lacquer layer 14.
  • the carrier 12 When using the multilayer body 10 as a stamping foil, in particular hot stamping foil or cold stamping foil, the carrier 12 is peeled off after the application of the multilayer body 10.
  • a protective lacquer layer 14 is preferably provided, which, after the carrier 12 has been removed, represents the outermost layer of the multi-layer body 10 in the applied state.
  • the fourth step in Figure 3 shows the application of a replication layer 15 and the introduction of a first asymmetric microstructure into the replication layer 15 in an ⁇ region to produce a first optically variable effect, and the introduction of a second asymmetric microstructure into the replication layer 15 in a ⁇ region to produce a second optically variable effect.
  • the first asymmetric microstructure and/or the second asymmetric microstructure are introduced by means of thermal replication or UV replication.
  • the ⁇ region and the ⁇ region are directly adjacent to one another.
  • the ⁇ region and the ⁇ region may be arranged at a distance from one another and/or partially overlapping and/or enclosing one another.
  • the first asymmetric microstructure is different from the second asymmetric microstructure, in particular the structural parameters of the first asymmetric microstructure are different from the structural parameters of the second asymmetric microstructure.
  • Figure 4a schematically shows the process steps c) to f) for producing a multilayer body 10 in detail.
  • Figure 4a shows arrows with numbers that are intended to delimit the individual process steps. The numbering in the arrows refers exclusively to the order of the process steps and should not be confused with the general reference symbols.
  • the precursor material 11 provided in Figure 3 with a replicated replication layer 15 acts as the starting material in the first step.
  • step c) is performed in the second step.
  • an absorber layer 16 is applied.
  • the absorber layer 16 is a semitransparent layer that reflects and/or absorbs a certain portion of the incident light. The remainder of the light passes through this layer.
  • the absorber layer 16 has a transmission in the range of 20% to 70%.
  • the absorber layer has an optical density OD in the range of 0.15 to 0.7.
  • the absorber layer 16 is a metal layer.
  • the absorber layer 16 comprises a material or combination of materials selected from: chromium, iron, tin, gold, copper, aluminum, titanium, silicon, and/or alloys thereof.
  • process step d) is carried out, i.e., the application of a dielectric layer.
  • the dielectric layer 17 preferably functions as a spacer layer in the thin-film structure.
  • the thickness and material of the dielectric layer significantly determine the generated color of the thin-film structure.
  • process step e namely the application of the reflector layer 18, is carried out.
  • the reflector layer 18 is preferably an opaque metal layer. It is preferably provided that the reflector layer 18 comprises a material or combination of materials selected from: aluminum, chromium, copper, tin, silver, indium, nickel, iron, gold, and/or an alloy of such metals. Thus, the reflector layer 18 is a metal layer or a metallization.
  • the reflector layer 18 is preferably applied or produced by vacuum deposition.
  • the deposition or application of the reflector layer 18 can be carried out over the entire surface or can be optionally retained over the entire surface or structured or partially removed using demetallization processes such as etching, lift-off, or photolithography, thus remaining only partially present.
  • the absorber layer 16 in step c), the dielectric layer 17 in step d), and the reflector layer 18 in step e) are each applied over the entire surface, particularly in the ⁇ - and ⁇ -ranges, with a consistent or homogeneous layer thickness.
  • at least one primer 19 is applied in the fifth step according to Figure 4a.
  • the at least one primer 19 is an adhesive that preferably increases or improves adhesion to other layers, for example, to the substrate 30 to which the multilayer body 10 is to be applied.
  • the at least one primer 19 is applied by means of a printing process and/or by casting and/or by doctoring.
  • Figure 4b schematically shows the process steps c) to f) for producing a multilayer body 10 in detail. Numbered arrows are shown in Figure 4b to delimit the individual process steps. The numbering in the arrows refers exclusively to the order of the process steps and should not be confused with the general reference symbols.
  • Figure 4b differs from Figure 4a in that steps c) and e) are reversed; thus, the layer sequences of absorber layer and reflector layer in Figure 4b are reversed compared to Figure 4a.
  • the precursor material 11 provided in Figure 3 with replicated replication layer 15 functions as the starting material in the first step.
  • step e) is carried out in the second step, namely the application of the reflector layer 18.
  • the reflector layer 18 is preferably an opaque metal layer. It is preferably provided that that the reflector layer 18 comprises a material or combination of materials selected from: aluminum, chromium, copper, tin, silver, indium, nickel, iron, gold, and/or an alloy of such metals.
  • the reflector layer 18 is a metal layer or a metallization.
  • the reflector layer 18 is preferably applied or produced by vacuum vapor deposition.
  • the vapor deposition or application of the reflector layer 18 can be carried out over the entire surface and optionally retained over the entire surface, or it can be partially removed using demetallization processes such as etching, lift-off, or photolithography, thus leaving only a partial surface or patterned surface.
  • process step d) is carried out, i.e., the application of a dielectric layer.
  • the dielectric layer 17 preferably functions as a spacer layer in the thin-film structure.
  • the thickness and material of the dielectric layer 17 significantly determine the generated color of the thin-film structure.
  • process step c namely the application of the absorber layer 16 is carried out.
  • the absorber layer 16 is a semi-transparent layer that reflects and/or absorbs a certain portion of the incident light. The rest of the light passes through this layer.
  • the absorber layer 16 preferably has a transmission in the range of 20% to 70%.
  • the absorber layer preferably has an optical density OD in the range of 0.15 to 0.7.
  • the absorber layer 16 is preferably a metal layer.
  • the absorber layer 16 comprises a material or combinations of materials selected from: chromium, iron, tin, gold, copper, aluminum, titanium, silicon and/or alloys thereof.
  • the absorber layer 16 in step c), the dielectric layer 17 in step d), and the reflector layer 18 in step e) are each applied over the entire surface, in particular in the ⁇ - and ⁇ -ranges, with a constant or homogeneous layer thickness.
  • at least one primer 19 is applied.
  • the at least one primer 19 is preferably an adhesive that preferably increases or improves the adhesion to other layers, for example, to the substrate 30 to which the multilayer body 10 is to be applied. It is particularly provided that the at least one primer 19 is applied by means of a printing process and/or by pouring and/or by doctoring.
  • Figure 5a schematically shows a multilayer body 10, in particular produced using a method according to Figure 1 or Figures 3 and 4a, in a plan view (top) and in a sectional view A-A' (bottom), in particular wherein the multilayer body 10 is applied to a substrate 30.
  • Applied means that the multilayer body 10 has been firmly bonded to a substrate 30 by means of an adhesive layer or the at least one primer 19 and that the carrier 12, with optional release layer 13, has then been removed.
  • the plan view (top) in Figure 5a shows that the ⁇ region and the ⁇ region are directly adjacent to one another.
  • the multilayer body 10 according to Figure 5a has two different color shift effects that are perceptible to the human eye and/or a sensor.
  • the applied multilayer body 10 viewed from top to bottom, has a protective lacquer layer 14, a replication layer 15, an absorber layer 16, a dielectric layer 17, a reflector layer 18 and a primer 19.Furthermore, in the applied multilayer body 10, a first asymmetric microstructure in the ⁇ range is incorporated into the replication layer 15 to generate a first optically variable effect, and a second asymmetric microstructure in the ⁇ range is incorporated to generate a second optically variable effect. These two optically variable effects are superimposed on a general color-shift effect, which is generated by the thin-film structure, which consists of the absorber layer 16, the dielectric layer, and the reflector layer 18.
  • a first color-shift effect is generated in the ⁇ range and a second color-shift effect is generated in the ⁇ range, with the first color-shift effect differing from the second color-shift effect.
  • the first color-shift effect differs from the second color-shift effect in its coloring or color impression.
  • the layer thickness of the absorber layer 16 in the ⁇ -range and ⁇ -range as well as the layer thickness of the dielectric layer in the ⁇ -range and in the ⁇ -range and the layer thickness of the reflector layer 18 in the ⁇ -range and ⁇ -range are homogeneous or constant. This is also indicated accordingly in Figure 5a. This measure ensures that the general color shift effect is identical across the ⁇ -range and ⁇ -range.
  • the first color shift effect and the second color shift effect are generated by the superposition of the optically variable effects with the general color shift effect.
  • the first asymmetric microstructure is different from the second asymmetric microstructure, in particular wherein the structural parameters of the first asymmetric microstructure are different from the structural parameters of the second asymmetric microstructure.
  • the first asymmetric microstructure and the second asymmetric microstructure are each configured as blazed gratings.
  • first asymmetric microstructure and/or the second asymmetric microstructure may have structures selected from: blazed gratings, micromirrors, microfacets, microprism structures, and/or Fresnel-like microstructures. Furthermore, it is possible for the first asymmetric microstructure and/or the second asymmetric microstructure to have an average lateral extent of at least 3 ⁇ m, in particular at least 5 ⁇ m. It is preferably provided that the grating lines of the first asymmetric microstructure and/or the second asymmetric microstructure, in particular the grating lines of the blazed gratings, are linear, curved, or corrugated.
  • the first asymmetric microstructure has a blaze angle ⁇ , through which, when light is incident perpendicularly onto the multilayer body, this incident light is deflected at a first defined angle ⁇ perpendicularly.
  • Figure 12 shows this illumination situation in a schematic side view of the multilayer body. Incident light is incident perpendicularly with respect to the x/y plane in which the multilayer body lies.
  • this angle ⁇ corresponds to the flank angle or blaze angle ⁇ .
  • the light that falls into the observer's eye has an angle ⁇ perpendicularly with respect to the perpendicularly incident light.
  • the first asymmetric microstructure preferably deflects at least 60% of the incident light, preferably at least 75% of the incident light, particularly preferably at least 90% of the incident light in a first angular range in the range from -40° to -6° and/or +6° to 40°, preferably in the range from -35° to -7° and/or +7° to +35°, more preferably in the range from -30° to -8° and/or +8° to 30°, particularly preferably in the range from -20° to -8° and/or +8° to +20°.
  • the greater the change in angle the greater the color change compared to the color impression of the multilayer body, in particular the multilayer structure, upon direct reflection on a mirror surface.
  • the second asymmetric microstructure deflects this incident light into a second defined angle when light is incident perpendicularly onto the multilayer body.
  • the second asymmetric microstructure deflects at least 60% of the incident light, preferably at least 75% of the incident light, particularly preferably at least 90% of the incident light, into a second angular range in the range from -5° to 0° and/or 0° to +5°, preferably in the range from -3° to 0° and/or 0° to +3°. Due to the small angular change, the color impression of the ⁇ range essentially corresponds to that of the multilayer body, in particular a multilayer structure, upon direct reflection on a mirror surface.
  • FIG. 5b schematically shows a multilayer body 10, in particular manufactured using a method according to Figure 1 or Figures 3 and 4a, in a plan view (top) and a sectional view AA' (bottom), in particular with the multilayer body 10 applied to a substrate 30.
  • the multilayer body 10 shown in Figure 5b essentially corresponds, in particular in terms of its layer structure, to the multilayer body 10 according to Figure 5a. However, the difference is that the ⁇ region and the ⁇ region are arranged differently in the multilayer body 10 shown in Figure 5b. Although the ⁇ region and the ⁇ region are also arranged directly adjacent to one another here, the two regions touch at two edges.
  • Figure 6a schematically shows a multilayer body 10, in particular produced using a method according to Figure 1 or Figures 3 and 4a, in a plan view (top) and in a sectional view B-B' (bottom), in particular wherein the multilayer body 10 is applied to a substrate 30. With regard to the structure of the multilayer body 10, the same statements apply here as for Figures 5a and 5b.
  • the multilayer body 10 according to Figure 6a has the difference that the ⁇ region completely surrounds the ⁇ region.
  • the ⁇ region is designed as a square and the ⁇ - area as a frame corresponding to the square.
  • Figure 6b schematically shows another multilayer body 10, in particular using a method according to Figure 1 or Figures 3 and 4a, in a plan view (top) and a sectional view B-B' (bottom), in particular with the multilayer body 10 applied to a substrate 30.
  • FIG. 6a schematically shows a multilayer body 10, in particular produced using a method according to Figure 1, in a plan view (top) and in a sectional view C-C' (bottom), in particular wherein the multilayer body 10 is applied to a substrate 30.
  • the layer structure of the multilayer body 10 is identical to the layer structure of the multilayer bodies 10 according to Figures 5a to 6b.
  • the multilayer body 10 shown in Figure 7 differs from the multilayer bodies 10 shown in Figures 5a to 6b in that the multilayer body 10 according to Figure 7 additionally has a ⁇ -region.
  • a ⁇ -region in the replication layer 15 is configured as a mirror surface.
  • a mirror surface is preferably referred to as a surface that is essentially flat. When viewed from above, perpendicular to this mirror surface, preferably A mirror surface is preferably only provided in the ⁇ -range if no mirror surface is present in the ⁇ -range.
  • the structures in the ⁇ -range can be subwavelength gratings, in particular subwavelength cross gratings, with a grating period between 150 nm and 500 nm, preferably between 200 nm and 350 nm.
  • the ⁇ -range shown in Figure 7 is arranged between the ⁇ -range and the ⁇ -range, so that the ⁇ -range optically separates the ⁇ -range from the ⁇ -range.
  • the absorber layer 16 in step c) and the dielectric layer 17 in step d) and the reflector layer 18 in step e) are each applied over the entire surface, in particular also in the ⁇ range, each with a constant or homogeneous layer thickness.
  • the absorber layer 16, the dielectric layer 17 and the reflector layer 18 are present in the ⁇ range, ⁇ range and ⁇ range, each with a constant layer thickness.
  • the observer in the ⁇ range sees the pure, general color-shift effect if, as shown in Figure 7, a flat surface, in particular a mirror surface, is present and thus no micro- or nanostructures are present which could be superimposed with the general color-shift effect of the thin-film structure.
  • the general color-shift effect perceptible in the ⁇ range differs from the first color-shift effect in the ⁇ range. From the ⁇ range The ⁇ -region differs by the absence of the optically variable effect of a microstructure (as shown in the example in Figure 7) or by another optically variable effect due to other micro- or nanostructures, e.g., subwavelength gratings.
  • Figure 8 schematically shows a multilayer body 10, in particular manufactured using a method according to Figure 1, in a plan view (top) and a sectional view D-D' (bottom), in particular with the multilayer body 10 applied to a substrate 30.
  • the multilayer body 10 shown in Figure 8 has an ⁇ -region, a ⁇ -region, and a ⁇ -region in which the thin-film structure is present.
  • the multilayer body 10 according to Figure 8 also has a ⁇ region in which the thin-film structure is not present.
  • the thin-film structure is at least partially structured or removed in the ⁇ region.
  • two ⁇ regions are provided.
  • the first ⁇ region is designed as a star and is completely surrounded by the ⁇ region.
  • the second ⁇ region is designed as a crescent and is completely surrounded by the ⁇ region.
  • the ⁇ region and the ⁇ region are optically separated by a ⁇ region.
  • the color effects or color shift effects produced in the ⁇ region, ⁇ region and ⁇ region are identical to those described for Figure 7.
  • a microstructure preferably an asymmetric microstructure, is also molded into the replication layer 15.
  • the thin-film structure in particular the absorber layer 16 and/or the The dielectric layer 17 and/or the reflector layer 18 are not present. Instead, only the at least one primer layer 19, the replication layer 15, and the protective lacquer layer 14 are present in the ⁇ range.
  • the structures molded into the replication layer 15 in the ⁇ range do not generate an optically variable effect. This is because the replication layer 15 and the directly adjacent at least one primer layer 19 have approximately the same refractive index in the ⁇ range. As a result, no effect due to light refraction, light diffraction, or light reflection, and thus no optically variable effect, can be generated.
  • the method for producing a multi-layer body 10 preferably further comprises carrying out the following steps: - at least partial application of a washable lift-off varnish, preferably in a ⁇ range, in particular by means of printing, preferably registered to the first asymmetric microstructure and/or second asymmetric microstructure, wherein the step is carried out after step b) and before step c); - removal of the lift-off varnish with a solvent in a washing process in order to remove the absorber layer 16 and the dielectric layer 17 and the reflector layer 18, in particular in the ⁇ range, wherein the step is carried out after step e) and before step f).
  • step e) and before step f) - applying a photoresist layer 20, in particular applying the photoresist layer 20 over the entire surface; - exposing and developing the photoresist layer 20 with an exposure mask 21, preferably in a ⁇ -range, in particular registering the first asymmetric microstructure and/or second asymmetric microstructure; - removing the reflector layer 18 in the ⁇ -range, in particular by etching, and removing the photoresist layer 20.
  • steps are schematically illustrated in Figure 9.
  • step 6 the photoresist layer 20 is exposed and developed in the ⁇ -range using an exposure mask 21.
  • the exposure mask 21 is preferably an external exposure mask 21, which is applied to the layer structure of the multilayer body 10, preferably in register or in exact registration.
  • the reflector layer 18 is etched wherever no photoresist layer 20 is present, and then the photoresist layer 20 is stripped or removed.
  • the eighth step is equivalent to step 5 according to Figure 4a, i.e., in the eighth step, at least one primer 19 is applied.
  • the ⁇ -range appears light gray to an observer in transmitted light. In reflected light, no or, if appropriate, a slight thin-film effect or color-shift effect is visible, which, however, is not as intense and strong as, for example, in the ⁇ -range and/or ⁇ -range and/or ⁇ -range.
  • This slight thin-film effect is preferably visible when the refractive index of the dielectric layer and the refractive index of the at least one primer, in particular the adhesive layer, have a sufficient difference.
  • the structuring of the reflector layer 18 can also be carried out using an etching resist.
  • step e) the steps are carried out after step e) and before step f): - Applying an etching resist layer such that the etching resist layer is not present in a ⁇ -range, preferably in register with the first asymmetric microstructure and/or second asymmetric microstructure; - Removing the reflector layer 18 in the ⁇ range, in particular by etching; - Optionally, washing or removing the etching resist layer.
  • the etching resist layer can optionally remain in the layer structure.
  • the ⁇ range Similar to the structuring of the reflector layer 18 using photoresist, the ⁇ range also appears light gray to an observer in transmitted light when structuring using etching resist. In reflected light, the observer sees no or possibly a slight thin-film effect or color-shift effect, which, however, is not as intense and strong as, for example, in the ⁇ range and/or ⁇ range and/or ⁇ range. This slight thin-film effect is preferably visible when the refractive index of the dielectric layer and the refractive index of the at least one primer, in particular adhesive layer, have a sufficient difference. In a preferred embodiment, it can also be provided that the dielectric layer 17 and the reflector layer 18 are structured in the ⁇ region.
  • step e) and before step f the following further steps are carried out in the method: - at least partially applying a washable lift-off varnish, preferably in a ⁇ region, in particular by means of printing, preferably registered to the first asymmetric microstructure and/or second asymmetric microstructure, wherein the step is carried out after step c) and before step d); - removing the lift-off varnish with a solvent in a washing process in order to remove the dielectric layer 17 and the reflector layer 18, in particular in the ⁇ region, wherein the step is carried out after step e) and before step f).
  • the ⁇ -region appears light gray to an observer in transmitted light. In reflected light, a slight, bright metallization with a mirror surface or structural effects is visible to the observer.
  • the following steps are further carried out in the method: - at least partial application of a washable lift-off varnish, preferably in a ⁇ -region, in particular by printing, preferably registered to the first asymmetric microstructure and/or second asymmetric microstructure, wherein the step is performed after step b) and before step c); - removing the lift-off varnish with a solvent in a washing process to remove the absorber layer 16, in particular in the ⁇ region, wherein the step is performed after step c) and before step d). Due to the structuring of the absorber layer 16, the ⁇ region appears dark to an observer in transmitted light, with little or no contrast difference in transmitted light compared to the ⁇ and ⁇ regions.
  • a silver layer with a mirror surface or structural effects is visible to the observer, which represents a clear contrast to the first color-shift effect and/or second color-shift effect and/or general color-shift effect.
  • the absorber layer 16 and dielectric layer 17 are partially removed in the ⁇ region.
  • the following steps are further carried out in the method: - at least partial application of a washable lift-off varnish, preferably in a ⁇ range, in particular by means of printing, preferably registered to the first asymmetric microstructure and/or second asymmetric microstructure, wherein the step is carried out after step b) and before step c); - removal of the lift-off varnish with a solvent in a washing process in order to remove the absorber layer 16 and the dielectric layer 17, in particular in the ⁇ range, wherein the step is carried out after step d) and before step e).
  • FIG. 10a shows a schematic sectional view of a multilayer body 10. To simplify the illustration, the multilayer body 10 is applied to a substrate 30 and whose carrier 12 and release layer 13 have been removed. However, the substrate 30 is not shown.
  • the multilayer body 10 exhibits two different color-shift effects perceptible to the human eye and/or a sensor.
  • the multilayer body 10 viewed from top to bottom, has a protective lacquer layer 14, a replication layer 15, an absorber layer 16, a dielectric layer 17, a reflector layer 18, and a primer 19.
  • a first asymmetric microstructure in the ⁇ range for generating a first optically variable effect and a second asymmetric microstructure in the ⁇ range for generating a second optically variable effect are introduced into the replication layer 15.
  • These two optically variable effects are superimposed with a general color shift effect, which is created by the thin-film structure, which is composed of the absorber layer 16, the dielectric layer, and the reflector layer 18.
  • a first color shift effect is generated in the ⁇ range and a second color shift effect is generated in the ⁇ range, whereby the first color shift effect differs from the second color shift effect.
  • the different color shift effects are preferably generated by different structural parameters of the first asymmetric microstructure and the second asymmetric microstructure.
  • blaze gratings were used as asymmetric microstructures.
  • the path difference of the light rays passing through the absorber layer 16 and reflected by the reflector layer 18 is sufficiently different in the ⁇ and ⁇ ranges compared to the light rays reflected by the absorber layer 16.
  • This path difference is preferably influenced by the blaze angle ⁇ .
  • the blaze angle ⁇ is formed between one flank of the microstructure and the x/y plane of the multilayer body 10.
  • the blaze angle can optionally be configured to vary within each ⁇ -range and/or ⁇ -range. This is due to the varying structural parameters, such as the structural width or the structural depth in the ⁇ -range and/or ⁇ -range.
  • the following Figures 11a to 11f each show a section of the multilayer body 10 shown in Figure 10 in the ⁇ -range or ⁇ -range under different lighting and viewing situations. The generated color shift effects are explained in more detail below with reference to Figures 11a to 11f.
  • Figures 11a to 11f the multilayer body 10 is now shown in a simplified manner, in which only the absorber layer 16, the dielectric layer 17 and the reflector layer 18 are depicted. Furthermore, for the sake of simplicity, the light refraction is not taken into account in the illustrations.
  • Figure 11a now schematically shows a blaze grating in the ⁇ region of the multilayer body 10 according to Figure 10.
  • Figure 11a shows a relatively flat blaze angle.
  • the lamp provides directed illumination at an angle of incidence ⁇ 1.
  • the incident light is reflected by both the absorber layer 16 (not shown here) and the reflector layer 18, resulting in a path difference between the light rays and thus in an initial color impression through interference.
  • FIG. 11b schematically shows a blaze grating in the ⁇ region of the multilayer body 10 according to Figure 10.
  • the light incident on the multilayer body 10, in particular the security element, from the directed light source does not reach the observer's eye. This is due, on the one hand, to the steeper blaze angle ⁇ steep.
  • the incident light from the directed light source reaches the observer's eye at an angle of incidence ⁇ 2 equal to the angle of reflection ⁇ 2 relative to the local plane of the thin-film structure.
  • the plane of the In this section of the ⁇ -region the thin-film structure is tilted by the angle ⁇ steep relative to the x/y plane. Due to the larger blaze angle ⁇ steep in the ⁇ -region compared to the blaze angle In the ⁇ range, the angle of incidence ⁇ 2 in the ⁇ range is smaller than the angle of incidence ⁇ 1 in the ⁇ range. This leads to a different path difference and thus to a different, second color impression for the observer, whereby the viewing position is always the same in the cases described in Figures 11a to 11c.
  • Figure 11d shows a schematic sectional view of the same section of the ⁇ range as already shown in Figure 11a, but with the difference that the light source is now arranged essentially perpendicular to the plane of the thin-film structure.
  • the directed illumination does not occur at the angle of incidence ⁇ 1.
  • the angle of incidence and angle of reflection are again shown in dashed lines in Figure 11d. This indicates that, in the specified lighting situation, no light enters the observer's eye.
  • the ⁇ range therefore appears dark to the observer under illumination directed essentially perpendicular to the plane of the thin-film structure.
  • Figure 11e again shows a schematic sectional view of the same section of the ⁇ -region as already shown in Figures 11a and 11d.
  • the illumination shown in Figure 11e is diffuse illumination and not directed illumination, as shown, for example, in Figures 11a or 11d.
  • Diffuse illumination means that approximately the same light intensity is incident on the multilayer body 10, in particular the security element, from all angles of incidence.
  • the light incident at the angle of incidence 1 relative to the plane of the thin-film structure of the multilayer body 10, in particular the security element, is reflected, analogously to Figure 11a, both at the semitransparent absorber layer 16 (not shown here) and at the reflector layer 18. reflected, resulting in a path difference of the light rays and thus in a first color impression due to interference.
  • Figure 11f again shows a schematic sectional view of the same section of the ⁇ -range as already shown in Figures 11b and 11c.
  • the illumination shown in Figure 11f is diffuse illumination and not directed illumination, as shown, for example, in Figures 11b or 11c. Similar to the ⁇ -range (see Figure 11e), in the ⁇ -range, incident light under diffuse illumination is also reflected by both the semitransparent absorber layer 16 (not shown here) and the reflector layer 18, resulting in a path difference of the light rays and thus in a second color impression due to interference. The second color impression described here is different from the first color impression described in Figure 11e.
  • the structural parameters already mentioned above are preferably provided for the first asymmetric microstructure and the second asymmetric microstructure. It is further provided that the first asymmetric microstructure deflects light incident perpendicularly onto the multilayer body at a first defined angle.
  • the first asymmetric microstructure deflects at least 60% of the incident light, preferably at least 75% of the incident light, particularly preferably at least 90% of the incident light, in a first angular range in the range from -40° to -6° and/or +6° to 40°, preferably in the range from -35° to -7° and/or +7° to +35°, more preferably in the range from -30° to -8°. and/or +8° to 30°, particularly preferably in the range from -20° to -8° and/or +8° to +20°.
  • the second asymmetric microstructure deflects light incident perpendicularly onto the multilayer body at a second defined angle.
  • the second asymmetric microstructure deflects at least 60% of the incident light, preferably at least 75% of the incident light, particularly preferably at least 90% of the incident light, in a second angular range in the range from -5° to 0° and/or 0° to +5°, preferably in the range from -3° to 0° and/or 0° to +3°.
  • the dielectric layer 17 has an optical thickness n ⁇ d in the range from 70 nm to 1200 nm, in particular from 500 nm to 1000 nm, preferably from 600 nm to 1000 nm, in particular wherein the optical thickness is determined from the product of the predetermined thickness of the dielectric layer d and the refractive index n of the dielectric layer.
  • the total area of the ⁇ -region is at least 4 mm 2 , more preferably at least 6 mm 2 , particularly preferably at least 9 mm 2 , wherein in particular the extent of the individual surfaces of the ⁇ -region in both the x-direction and the y-direction is at least 1 mm, preferably at least 2 mm.
  • the total area of the ⁇ -region is at least 4 mm 2 , more preferably at least 6 mm 2 , particularly preferably at least 9 mm 2 , wherein in particular the extent of the individual surfaces of the ⁇ -region in both the x-direction and the y-direction is at least 1 mm, preferably at least 2 mm.
  • Figure 13a shows a schematic top view of a security document, here a banknote of denomination 42, with a multilayer body 10 in the form of a registered thread foil.
  • the substrate 30 of the banknote has three window areas in which partial areas of the thread foil can be seen.
  • the thread foil By positioning the thread foil in register with the window areas of the security document, defined areas of the thread foil can be seen in the window areas.
  • the two window areas closer to the edge of the banknote each show a full-surface ⁇ -area with an embedded star-shaped ⁇ -area.
  • a ⁇ -area with an embedded crescent-shaped ⁇ -area can be seen.
  • the ⁇ -areas and ⁇ -areas, and thus the associated window areas, show the first color-shift effect and the second color-shift effect.
  • the ⁇ -regions are transparent, i.e., the underlying substrate 30 of the banknote is visible.
  • Figure 13b also shows a schematic top view of a security document, here a banknote of denomination 42, with a multilayer body 10 in the form of a registered thread foil.
  • all three window regions here each show a full-surface ⁇ -region. Embedded within these are ⁇ -regions in the shape of a star, or in the central window region in the shape of a crescent. The ⁇ -regions and ⁇ -regions again show the first color-shift effect and the second color-shift effect.
  • ⁇ 1 Providing a precursor material 2 Incorporating asymmetric microstructures into the replication layer 3 Applying an absorber layer 4 Applying a dielectric layer 5 Applying a reflector layer 6 Applying at least one primer 7 Applying at least one functional layer 10 Multilayer body 11 Precursor material 12 Carrier 13 Release layer 14 Protective lacquer layer 15 Replication layer 16 Absorber layer 17 Dielectric layer 18 Reflector layer 19 Primer 20 Photoresist layer 21 Exposure mask 30 Substrate d Predetermined thickness ⁇ ⁇ -region ⁇ ⁇ -region ⁇ ⁇ -region ⁇ ⁇ -region ⁇ ⁇ -region ⁇ blaze angle ⁇ angle of incidence, angle of reflection first defined angle, second defined angle ⁇ angle of incidence

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Abstract

L'invention concerne un élément multicouche (10), en particulier un élément de sécurité pour sauvegarder des documents de sécurité, ayant au moins deux effets de distorsion de couleur différents qui peuvent être perçus par l'oeil humain et/ou un capteur. L'élément multicouche (10) comporte un pré-matériau (11), et l'élément multicouche (10) comprend en outre les couches suivantes, qui sont appliquées sur la couche de réplication (15) dans l'ordre suivant en particulier : une couche absorbante (16), une couche diélectrique (17) ayant une épaisseur spécifiée, une couche de réflecteur (18) et au moins une amorce (19). Une première microstructure asymétrique est introduite dans la couche de réplication (15) dans une région α (α) afin de produire un premier effet optiquement variable, et une seconde microstructure asymétrique est introduite dans une région β (β) afin de produire un second effet optiquement variable. Afin de générer les deux effets de distorsion de couleur différents dans l'élément multicouche (10), la couche absorbante (16), la couche diélectrique (17) et la couche de réflecteur (18) génèrent un effet de distorsion de couleur général qui est superposé sur le premier effet optiquement variable dans la région α (α) et sur le second effet optiquement variable dans la région β (β) de telle sorte qu'un premier effet de distorsion de couleur est généré dans la région α (α) et un second effet de distorsion de couleur est généré dans la région β (β), le premier effet de distorsion de couleur étant différent du second effet de distorsion de couleur.
PCT/EP2024/078204 2023-10-13 2024-10-08 Élément multicouche et procédé de production d'un élément multicouche Pending WO2025078330A1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
DE102023128034.1 2023-10-13
DE102023128034.1A DE102023128034A1 (de) 2023-10-13 2023-10-13 Mehrschichtkörper sowie Verfahren zur Herstellung eines Mehrschichtkörpers
DE102024109191 2024-04-02
DE102024109191.6 2024-04-02

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WO2025078330A1 true WO2025078330A1 (fr) 2025-04-17

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3858977A (en) 1972-01-18 1975-01-07 Canadian Patents Dev Optical interference authenticating means
DE2408304A1 (de) 1974-02-21 1975-09-04 Claus Jung Wasserzeichenpapier-former zur herstellung von papieren mit echten, plazierten wasserzeichen und eingebetteten sicherheitsfaeden
EP1846253B1 (fr) * 2005-02-10 2008-09-17 OVD Kinegram AG Procede de production d'un corps multicouche et corps multicouche correspondant
US20140077487A1 (en) * 2011-05-25 2014-03-20 Toppan Printing Co., Ltd. Coloring forgery prevention structure and coloring forgery prevention medium
DE102007005416B4 (de) * 2007-01-30 2016-03-31 Leonhard Kurz Gmbh & Co. Kg Prägefolie und damit gebildeter Sicherheitsaufkleber
EP4035903A1 (fr) * 2019-09-29 2022-08-03 Zhongchao Special Security Technology Co., Ltd Élément anti-contrefaçon optique à corps multicouche et son procédé de fabrication

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3858977A (en) 1972-01-18 1975-01-07 Canadian Patents Dev Optical interference authenticating means
DE2408304A1 (de) 1974-02-21 1975-09-04 Claus Jung Wasserzeichenpapier-former zur herstellung von papieren mit echten, plazierten wasserzeichen und eingebetteten sicherheitsfaeden
EP1846253B1 (fr) * 2005-02-10 2008-09-17 OVD Kinegram AG Procede de production d'un corps multicouche et corps multicouche correspondant
DE102007005416B4 (de) * 2007-01-30 2016-03-31 Leonhard Kurz Gmbh & Co. Kg Prägefolie und damit gebildeter Sicherheitsaufkleber
US20140077487A1 (en) * 2011-05-25 2014-03-20 Toppan Printing Co., Ltd. Coloring forgery prevention structure and coloring forgery prevention medium
EP4035903A1 (fr) * 2019-09-29 2022-08-03 Zhongchao Special Security Technology Co., Ltd Élément anti-contrefaçon optique à corps multicouche et son procédé de fabrication

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