CN111836727B - Security element, data carrier and method - Google Patents

Abstract

The invention relates to a security element for protecting a value document, security document or value item, having a predetermined region which, when illuminated with diffuse illumination, in particular when viewed in daylight, appears to an observer in a first visually perceptible color and, when illuminated with a punctiform light source, in particular when viewed in the dark, appears in a second visually perceptible color and forms a marking in the form of a pattern, a character or a code which is not visible to the observer when illuminated with diffuse illumination, in particular when viewed in daylight, and is only visible when illuminated with a punctiform light source, in particular when viewed in the dark, of a smartphone, wherein the security element comprises a layer having a reflective microstructure and a translucent functional layer facing the observer, and the translucent functional layer is configured such that the translucent functional layer has a first visually detectable color when viewed in reflected light and a second visually detectable color when viewed in transmitted light.

Description

Security element, data carrier and method

Technical Field

The invention relates to a security element, a data carrier comprising a security element, in particular a value document, a security document or a value item. The invention also relates to the use of security elements for protecting data carriers, in particular number plates or license plates, traffic signs or boards, advertising panels or surfaces, or safety clothing, which are provided with retroreflective or retroreflective structures.

Background

Value documents and security documents, such as banknotes, value documents or authentication documents, or also other value articles, such as nameplate goods, are often provided with security elements for security purposes, which allow the authenticity of the data carrier to be checked and at the same time serve to prevent unauthorized copying. The security element can be configured, for example, as a security thread embedded in a banknote, as a patch arranged on a banknote, as a pattern of, for example, a transfer element or a cover film for covering an opening in a banknote, a security strip, or as a pattern of characteristic regions placed directly on a document of value.

What plays a particular role in ensuring authenticity is a security element that exhibits a viewing angle-dependent visual effect, since even with the most modern reproduction devices it is not possible to reproduce the security element. In the prior art, it is known, for example, to represent objects by means of reflective microstructures, which objects produce a movement effect when tilting and/or rotating a value document provided with a security element. For example, reference is made to WO 2015/078572A1 and WO 2016/180522A 1. The reflective microstructure comprises micro-reflective means patterned so as to produce a planar security element with multiple pixels, which security element comprises at least one micro-reflective means (i.e. at least one optically active surface) each. The planar shape of the security element defines a main plane. The micro-reflective device is oriented such that the object produces a movement effect with reference to the main plane when tilting and/or rotating the security element. Instead of a movement effect, the object may also exhibit a tilting effect. Three-dimensionally imaged objects are known from patent document WO2011/066990a2, which appear to the observer as a back-and-forth curve in the main plane. The position of the object relative to the main plane remains unchanged when tilting the security element.

Disclosure of Invention

The object of the invention is to provide a security element with increased security against forgery.

This technical problem is solved by the following technical solution of the present invention.

Summary of The Invention

1. (first aspect of the invention) a security element for protecting (absicher) value documents, security documents or value articles, having a predetermined area which appears in a first visually perceptible color to an observer in diffuse illumination, in particular when viewed in daylight, and which appears in a second visually perceptible color when illuminated with a punctiform light source, in particular when viewed in dark space with a flashlight of a smartphone, and forms a marking in the form of a pattern, a character or a code which is not visible to the observer in diffuse illumination, in particular when viewed in daylight, and which is only visible when illuminated with a punctiform light source, in particular when viewed in dark space with a flashlight of a smartphone, wherein the security element comprises a layer having a reflective microstructure and a translucent functional layer facing the observer, and the translucent functional layer is configured such that the translucent functional layer has a first visually perceptible color when viewed in reflected light and a second visually perceptible color when viewed in transmitted light.

(preferred embodiment) the security element according to statement 1, wherein the reflective microstructures are configured as retroreflective structures having triangular or tetragonal cube corners or as retroreflective structures based on microglass beads, wherein the retroreflective structures are preferably provided with a metallized layer, further preferably with a specular reflective metal coating.

(preferred design) the security element according to statement 1, wherein the reflective microstructures are formed in the form of an inlay consisting of a plurality of reflective inlay elements which are characterized by the parameters size, contour shape, relief shape, reflection power and spatial orientation, and which are formed such that the marking in the form of a pattern, character or code has a dynamic shifting effect when the security element is tilted in such a way that the various inlay elements with different characteristic parameters reflect the impinging light into different spatial regions.

(preferred embodiment) the security element according to one of the provisions 1 to 3, wherein the layer with the reflective microstructure is present in the form of a metallized embossing lacquer layer.

(preferred embodiment) the security element according to one of the provisions 1 to 4, wherein the marking in the form of a pattern, a character or a code is formed by a recess in an opaque layer which is arranged between the translucent functional layer and the layer having the retroreflective structure, wherein the opaque layer is in particular a metallized layer or a color layer.

(preferred design) the security element according toclaim 5, as referred to inclaim 3, wherein the recesses in the opaque layer form first marks in the form of patterns, characters or codes, and the reflective microstructures form second marks in the form of patterns, characters or codes in the form of an inlay consisting of a plurality of reflective inlay elements, wherein the second marks preferably at least partially accommodate the first marks.

(preferred embodiment) the security element according to one of provisions 1 to 6, wherein the translucent functional layer has a multilayer structure with two translucent metal layers and a dielectric layer arranged between the two translucent metal layers.

(preferred embodiment) the security element according torule 7, wherein the two translucent metal layers are formed independently of one another by metals, and the metals are each selected from the group consisting of Al, Ag, Ni, Cr, Cu, Au, Si and alloys of one or more of the foregoing elements, and the dielectric layer is SiO₂ Layer, ZnO layer, ZnS layer, Al₂ O₃ Layer, TiO₂ A layer, a layer composed of a nitride or oxynitride of Si, Zn, Al or Ti, or MgF₂ Layers or nitrocellulose layers, for example, which are available in printing technology.

(preferred embodiment) the security element according toclaim 7 or 8, wherein the two translucent metal layers are selected independently of one another from Al or Ag, and the dielectric layer is SiO₂ And (3) a layer.

(preferred embodiment) the security element according to one of the provisions 1 to 6, wherein the translucent functional layer is obtainable in printing technology by means of an effect pigment composition.

(preferred embodiment) according to one of the provisions 1 to 6Security element, wherein the translucent functional layer has a multilayer structure based on an interference layer consisting only of a transparent layer, wherein the multilayer structure is based in particular on TiO₂ 、Al₂ O₃ Or other dielectric, preferably alternating layers.

(preferred embodiment) the security element according to one of the provisions 1 to 6, wherein the semitransparent functional layer is based on a plasmonic color filter and in particular on two-dimensional periodic nanostructures. Plasmonic color filters based on two-dimensional periodic nanostructures are known, for example, from DE 102011101635a 1.

(preferred embodiment) the security element according to one of the provisions 1 to 12, wherein the predetermined area appears golden to an observer when illuminated diffusely, in particular when viewed in daylight, and blue when illuminated with a point-like light source, in particular when viewed in dark space with a flashlight of a smartphone.

(preferred embodiment) the security element according to one of the statements 1 to 13, wherein the security element has the following structure:

-an adhesive layer;

-a layer having reflective microstructures;

-optionally, an opaque layer with hollows in the form of patterns, characters or codes;

-a translucent functional layer;

-a carrier film.

(preferred embodiment) the security element according to one of the provisions 1 to 13, wherein the security element has the following structure:

-an adhesive layer;

-a layer having reflective microstructures;

-a carrier film;

-a translucent functional layer;

wherein an opaque layer with recesses in the form of patterns, characters or codings is optionally arranged between the layer with reflective microstructures and the carrier film or between the carrier film and the translucent functional layer.

(preferred embodiment) the security element according toclaim 14 or 15, wherein an embossing lacquer layer with an embossing relief is arranged between the carrier film and the translucent functional layer, wherein the embossing relief is in particular a relief with a microstructure and/or a nanostructure.

(second aspect of the invention) a data carrier, in particular a value document, security document or value item, comprising a security element according to one of the provisions 1 to 16.

(third aspect of the invention) a security element for protecting a data carrier provided with a retroreflective structure, wherein the security element has a predetermined area which, when illuminated diffusely, in particular when viewed in daylight, appears to an observer in a first visually perceptible color and, when illuminated with a punctiform light source, in particular when viewed in dark space with a flashlight of a smartphone, appears in a second visually perceptible color, and wherein the predetermined area forms a marking in the form of a pattern, a character or a code which is invisible to the observer when illuminated diffusely, in particular when viewed in daylight, and which is visible when illuminated with a punctiform light source, in particular when viewed in dark space with a flashlight of a smartphone, wherein the security element comprises means adapted to associate the security element with the data carrier to be protected, The data carrier provided with a retroreflective structure comprises an adhesive layer to which the data carrier is bonded and a translucent functional layer facing the viewer, and the translucent functional layer is designed such that the translucent functional layer has a first visually perceptible color when viewed in reflected light and a second visually perceptible color when viewed in transmitted light.

Preferably, the retroreflective structures of the data carrier are based on reflective microstructures, in particular in the form of retroreflective structures having triangular or tetragonal cube corners or in the form of retroreflective structures based on microglass beads, wherein the reflective microstructures are preferably provided with a metallized layer, further preferably with a specularly reflective metal coating.

(preferred design) the security element according torule 18, wherein the marking in the form of a pattern, a character or a code is formed by a recess in an opaque layer which is arranged between the translucent functional layer and the adhesive layer.

(preferred embodiment) the security element according toclaim 18 or 19, wherein the translucent functional layer has a multilayer structure with two translucent metal layers and a dielectric layer arranged between the two translucent metal layers.

(preferred design) the security element according torule 20, wherein the two translucent metal layers are formed independently of one another from a metal, and the metal is selected from Al, Ag, Ni, Cr, Cu, Au, Si and alloys of one or more of the aforementioned elements, and the dielectric layer is SiO₂ Layer, ZnO layer, ZnS layer, Al₂ O₃ Layer, TiO₂ A layer, a layer composed of a nitride or oxynitride of Si, Zn, Al or Ti, or MgF₂ Layers or nitrocellulose layers, for example, which are available in printing technology.

(preferred embodiment) the security element according to claim 20 or 21, wherein the two translucent metal layers are selected independently of one another from Al or Ag, and the dielectric layer is SiO₂ And (3) a layer.

(preferred embodiment) the security element according to one of the provisions 1 to 6, wherein the translucent functional layer is obtainable in printing technology by means of an effect pigment composition.

(preferred embodiment) the security element according toclaim 18 or 19, wherein the translucent functional layer has a multilayer structure based on an interference layer consisting only of a transparent layer, wherein the multilayer structure is based in particular on an interference layer consisting of TiO₂ 、Al₂ O₃ Or other dielectric, preferably alternating layers.

(preferred design) the security element according toclause 18 or 19, wherein the translucent functional layer is based on a plasmonic color filter and in particular on two-dimensional periodic nanostructures. Plasmonic color filters based on two-dimensional periodic nanostructures are known, for example, from patent document DE 102011101635a 1.

(preferred embodiment) the security element according to one of theprovisions 18 to 25, wherein the predetermined area appears golden to an observer when illuminated diffusely, in particular when viewed in daylight, and blue when illuminated with a point-like light source, in particular when viewed in dark space with a flashlight of a smartphone.

(preferred embodiment) the security element according to one of theprovisions 18 to 26, wherein the security element has the following structure:

-an adhesive layer;

-optionally, an opaque layer with hollows in the form of patterns, characters or codes;

-a translucent functional layer;

-a carrier film.

(fourth aspect of the invention) a data carrier, in particular a number plate or license plate, traffic sign or sign, advertising panel or advertising surface, or safety garment, provided with a retroreflective structure, comprising a security element according to one of theprovisions 18 to 27.

(fifth aspect of the invention) use of a security element according to one of theprovisions 18 to 27 for protecting a data carrier provided with a retroreflective structure, in particular a number plate or license plate, a traffic sign plate or sign, an advertising plate or surface, or a security garment.

Detailed Description

In the context of the present invention, viewing under reflected light means that the respective object is illuminated from one side and viewed from the same side.

In the context of the present invention, viewing in transmitted light means illuminating the respective object from one side and viewing the object from the opposite side.

Diffuse light, known as diffuse lighting, uniformly illuminates a scene with little contrast or little shadowing. The diffused light is generated in the surface light source.

According to the invention, attractive security elements (or security elements) are provided which have interesting color changes in the case of changing the viewing, for example a gold color when illuminated diffusely changes to a blue color when illuminated with a point light source, on the one hand when viewed in diffuse illumination, in particular in daylight, and on the other hand when illuminated with a point light source, in particular with a flashlight of a smartphone, in a dark space. Further, when observing a photograph taken with the smartphone camera with the flash turned on, the observer can obtain the same appearance as when observing with a point light source, particularly when observing with the flashlight of the smartphone in a dark space.

According to a first aspect, a reflective microstructure in the form of an inlay consisting of a plurality of reflective inlay elements (or so-called reflective inlay elements) can be used for the layer with a reflective microstructure, which are characterized by the parameters size, contour shape, relief shape, reflectivity and spatial orientation, and which are constructed such that, when the security element is tilted, the marking in the form of a pattern, character or code has a dynamic movement effect in such a way that sets of inlay elements with different characteristic parameters reflect incident light into different spatial regions. The inlay element preferably has side dimensions of less than 30 μm and below the resolution limit of the naked eye. Preferably, the marking in the form of a pattern, a character or a code is configured as a motif in the form of an embossing structure in the embossing lacquer layer, wherein the embossing structure has raised embossing elements with differently oriented flat areas. The embossed structure here consists of a reflective microstructure in the form of an inlay consisting of a plurality of reflective inlay elements which are characterized by the parameters size, profile shape, relief shape, reflectivity and spatial orientation. Reflective microstructures for objects which are manifested in a shifting effect when tilting and/or rotating a document of value provided with a security element are known from the prior art, see for example documents WO 2015/078572a1, WO 2016/180522a1 and WO2011/066990a 2. The reflective microstructures may preferably produce a planar security element having a plurality of pixels each comprising at least one reflective mosaic element, i.e. at least one optically active face. The planar shape of the security element defines a main plane. The reflective inlay element is preferably oriented such that the object produces a movement effect with reference to the main plane when tilting and/or rotating the security element. Instead of a movement effect, the object may also exhibit a tilting effect. Three-dimensional visualization objects are known from patent document WO2011/066990a2, which are visualized to the viewer in a form curved back and forth in a main plane. The position of the object relative to the main plane remains unchanged when the security element is tilted.

According to a second aspect, retroreflective structures can be used for layers having reflective microstructures. Retroreflective structures are known in the prior art which, for example, cast the light of a vehicle headlamp back in the direction of the driver in order to improve visibility and may, for example, employ triangular or quadrangular cube corners or be based on microglass beads, see for example documents US 4763985A, US 20090300953A 1, WO2014/117086a1,US 6413615B 2 and US 4478769 a. The cube-corner structure may for example be based on an embossed relief structure that is specularly reflective with a reflective metal layer. The cube-corner structures can be present in particular as triangular surfaces or as tetragonal surfaces. The relief structure is expediently embossed in the plastic material or in a UV lacquer.

The security element according to the invention is expediently provided on the basis of a carrier film, for example polyethylene terephthalate (PET), polymethyl methacrylate (PMMA), polypropylene (PP), Polyethylene (PE), Polycarbonate (PC) or the like.

The layer having a retroreflective structure can expediently be present in a layer thickness in the range from 10 μm to 200 μm, preferably in the range from 30 μm to 150 μm, and particularly preferably in the range from 40 μm to 150 μm. The height of the retroreflective structures, in particular the triangular or quadrangular cube corners, expediently takes on a value of at least 10 μm, preferably at least 30 μm, and expediently less than 200 μm, preferably less than 150 μm.

The translucent functional layer has different color shades when viewed in reflected light on the one hand and when viewed in transmitted light on the other hand. The two different hues are, for example, complementary colors. Such a translucent functional layer is in particular based on a so-called fabry-perot lamellar element of a multilayer structure having two translucent metal layers and a dielectric layer arranged between the two translucent metal layers. Such a multilayer structure which appears golden when viewed in reflected light and blue hue when viewed in transmitted light is known, for example, from patent document WO 2011/082761 a 1.

A suitable multilayer structure having two translucent metal layers and a dielectric layer arranged between the two translucent metal layers preferably has the following specific features:

the two translucent metal layers are preferably selected from Al or Ag; dielectric layer, especially SiO₂ Layer or MgF₂ Layer, preferably SiO₂ A layer;

in the case of Al for both translucent metal layers, the respective preferred layer thickness is in the range from 5nm to 20nm, particularly preferably in the range from 10nm to 14 nm; dielectric SiO₂ The layer has a layer thickness preferably in the range from 50nm to 600nm, further preferably in the range from 80nm to 260nm and particularly preferably in the range from 210nm to 260nm, wherein the ranges from 80nm to 100nm and from 220nm to 240nm are particularly preferably used in particular for providing a gold/blue discoloration;

in the case of Ag for both translucent metal layers, the respective preferred layer thickness is in the range from 15nm to 30nm, particularly preferably in the range from 15nm to 25 nm; dielectric SiO₂ The layer has a layer thickness preferably in the range from 50nm to 600nm, further preferably in the range from 80nm to 260nm, and particularly preferably in the range from 210nm to 260nm, wherein the ranges from 80nm to 100nm and from 220nm to 240nm are particularly preferably used in particular for providing a gold/blue discoloration.

The above-described multilayer structure having two translucent metal layers and a dielectric layer disposed between the two translucent metal layers may have a symmetrical three-layer structure in which the material and layer thicknesses of the two translucent metal layers are uniform. However, there may alternatively be an asymmetrical three-layer structure in which the two translucent metal layers differ in material and/or layer thickness, for example:

-a silver/dielectric/aluminium layer system, wherein the layer thicknesses of the silver layer and the aluminium layer are identical or different;

-a silver/dielectric/silver layer system, wherein the layer thicknesses of the two silver layers are different;

an aluminum/dielectric/aluminum layer system, wherein the layer thicknesses of the two aluminum layers are different.

The above-described multilayer layer structure not only enables the production of translucent functional layers which appear golden when viewed in reflected light and blue tinge when viewed in transmitted light, but can also produce other discolorations depending on the choice of the layer thicknesses, in particular of the dielectric layer, for example:

-magenta in reflected light and cyan in transmitted light;

-turquoise in reflected light and orange-yellow in transmitted light;

-gold in reflected light and blue-violet in transmitted light;

silver in reflected light and violet in transmitted light.

Furthermore, translucent functional layers having different hues when viewed in reflected light on the one hand and when viewed in transmitted light on the other hand can be based on effect pigment compositions. Printed layers based on effect pigment compositions which, when viewed in reflected light, exhibit a different color than when viewed in transmitted light, in particular a gold/blue, gold/violet, green-gold/magenta, violet/green or silver/opaque color change, are described, for example, in patent document WO2011/064162a 2. The pigment preferably has the longest dimension (longest boundary length dimension) from end to end in the range of 15nm to 1000nm, and a transition metal selected from Cu, Ag, Au, Zn, Cd, Ti, Cr, Mn, Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, and Pt is used. The transition metal is preferably Ag. The length to thickness ratio (i.e. the ratio of the longest dimension end to thickness) is preferably at least 1.5, especially in the range 1.5 to 300. The ratio of binder to metal pigment is preferably less than 10:1, in particular less than 5: 1. Depending on the choice of the length-to-thickness ratio of the pigment, the longest dimension of the pigment end-to-end and the setting of the pigment/binder ratio, the color when the printed layer is viewed in transmission and the color when the printed layer is viewed in reflection can be adjusted (e.g. blue in transmission and silver, gold, bronze, copper or purple in reflection; furthermore a different color of purple, magenta, pink, green or brown in transmission and appearing in reflection according to the choice of the pigment/binder ratio). An ink having a gold/blue color change between reflection and transmission (in other words, between reflected light observation and transmitted light observation) has been mentioned in, for example, examples 1, 2 and 3 in table 1 of patent document WO2011/064162a 2. Further, example 4 shows an ink having a gold/violet color change, example 5 shows an ink having a green gold/magenta color change, example 7 shows an ink having a violet/green color change and example 8 shows an ink having a silver/opaque color change.

The security element according to the invention expediently has the following structure, wherein additional layers and films are conceivable:

an adhesive layer, for example an adhesive layer suitable for mounting a security element on a value document substrate, for example a banknote substrate;

-a layer having reflective microstructures;

-optionally an opaque layer with hollows in the form of patterns, characters or codes;

-a translucent functional layer;

-a carrier film.

According to an aspect, the security element according to the invention has the following structure, wherein additional layers and films are conceivable:

an adhesive layer, for example an adhesive layer suitable for mounting a security element on a value document substrate, for example a banknote substrate;

-a layer having reflective microstructures;

-a carrier film;

-a translucent functional layer;

optionally a protective lacquer or film in order to protect the translucent functional layer from harmful environmental influences;

wherein an opaque layer having recesses in the form of patterns, characters or codings is optionally arranged between the layer having the reflective microstructures and the carrier layer or between the carrier film and the translucent functional layer.

The opaque layer can be, in particular, a metallization layer obtained, for example, by means of vapor deposition or a color layer obtained by means of a printing method. The generation of structured metallization layers by means of a rinsing process is known from the prior art, see for example document EP 1972462B 1 and the prior art cited therein. Furthermore, for the production of the color layer, flake-like metallic pigments can be used, which are known, for example, from documents WO 2013/186167 a2, WO2010/069823a2, WO 2005/051675a2 (see, for example, the description therein onpage 11,line 10 topage 12, penultimate paragraph) and WO2011/064162 A3. The platelet-shaped metallic pigments described therein have the advantage that they adapt well to the base of the relief with relief structures, in particular with microstructures and/or nanostructures, so that differences from conventional metallization layers obtained by means of vapor deposition are hardly discernible. Simple production of the reflective layer in terms of printing technology makes it possible to dispense with complicated method steps, such as printing the desired hollow shapes in the reflective layer to be produced with a soluble flushing colour on a carrier, producing the metallization layer by vapor deposition and flushing away the flushing colour together with the metallization layer arranged above the flushing colour.

An embossing lacquer layer having an embossed relief, in particular a micro-structured and/or nano-structured relief, can be expediently arranged between the carrier film and the translucent functional layer. The translucent functional layer is adapted to the relief so that an observer can obtain additional optically variable information in the form of, for example, a pattern, a character or a code in reflected light when viewing the security element. Optically variable security elements with microstructures suitable for the protection of banknotes are known, for example, from patent document WO 2007/079851 a1 and from patent document WO 2011/066991 a2, as described above.

Furthermore, the security element according to the invention can have a marking in the form of a code, for example in the form of a one-dimensional bar code or a two-dimensional code or a QR code. Such a code can be conveniently scanned with a smartphone.

The security element according to the invention may be present in particular as a patch or label, as a strip or as a thread. In particular, the security element can also be present in the form of a transfer element which is formed on a temporary carrier.

Drawings

Further embodiments and advantages of the invention are explained below with reference to the drawings, which are schematically and strongly simplified, wherein the representation on scale and to scale is omitted in order to improve the clarity of the description. In the drawings:

fig. 1 shows a security element according to the invention according to a first embodiment in a cross-sectional view;

fig. 2 shows a security element according to the invention according to a second embodiment in a cross-sectional view;

fig. 3 shows a security element according to the invention according to a third embodiment in a top view when viewed in daylight;

fig. 4 shows a security element according to a third embodiment in a top view when viewed with a flashlight of a smartphone in a dark space;

fig. 5 and 6 show schematic diagrams for illustrating the functional principle of the solution according to the invention;

fig. 7 shows a security element according to the invention according to a fourth embodiment in a cross-sectional view;

fig. 8 shows a security element according to the invention according to a third embodiment in cross-section;

FIG. 9 illustrates an embodiment of a retroreflective structure in a top view;

FIG. 10 illustrates other embodiments of retroreflective structures in a top view;

fig. 11 shows an embodiment of a security element according to the invention, which is suitable for protecting a motor vehicle license plate.

Detailed Description

Fig. 1 shows a security element 1 according to the invention according to a first embodiment in a cross-sectional view. Reflective microstructureIn an example formed by a retroreflective structure. The security element 1 is based on acarrier film 2, for example a polyethylene terephthalate (PET) film, which is provided with a translucentfunctional layer 3 on the side facing the viewer. The translucentfunctional layer 3 can be obtained by means of vapor deposition and has a structure with two translucent Al layers and SiO arranged between the two translucent Al layers₂ A multilayer structure of layers. The translucentfunctional layer 3 appears golden when viewed in reflected light and blue in hue when viewed in transmitted light. Thecarrier layer 2 is provided with anembossing lacquer layer 4 on the side facing the translucentfunctional layer 3. Theembossing lacquer layer 4 is based on, for example, a UV lacquer in which the relief of the retroreflective structure is embossed. The relief of theembossing lacquer layer 4 is provided with a specularlyreflective metal coating 5, for example an aluminum metallization layer, in order in this way to form a retroreflective structure together with the relief of theembossing lacquer layer 4. Adjacent to the specularlyreflective metal coating 5, anadhesive layer 6 is arranged, for example, which is suitable for mounting the security element 1 on a document of value substrate, for example a banknote.

Fig. 2 shows asecurity element 7 according to the invention according to a second embodiment in a cross-sectional view. The reflective microstructures are formed, for example, by retroreflective structures. Thesecurity element 7 is based on a carrier film 8, for example a polyethylene terephthalate (PET) film, which in the present example forms the outer layer of thesecurity element 7. A translucentfunctional layer 9 is arranged on the inside of the carrier film 8. The translucentfunctional layer 9 can be obtained by means of vapor deposition and has a structure with two translucent Al layers and SiO arranged between the two translucent Al layers₂ A multilayer structure of layers. The translucentfunctional layer 9 appears golden when viewed in reflected light and blue in hue when viewed in transmitted light. The translucentfunctional layer 9 is provided with anembossing lacquer layer 10 on the side facing the carrier film 8. Theembossing lacquer layer 10 is based on a UV lacquer in which the relief of the retroreflective structures is embossed. The relief of theembossing lacquer layer 10 is provided with a specularlyreflective metal coating 11, for example an aluminum metallization layer, in order in this way to form a retroreflective structure together with the relief of theembossing lacquer layer 10. Adjacent to the specularlyreflective metal coating 11, for example, anadhesive layer 12 is arranged which is suitable for the arrangement of theretroreflective film 7 on a document of value substrate, for example a banknote.

Fig. 3 shows asecurity element 13 according to the invention according to a third embodiment in a plan view, viewed in daylight. Thesecurity element 13 appears to the viewer in the form of a gold-coloured metal surface.

Fig. 4 shows a top view of asecurity element 13 according to the invention according to a third embodiment when illuminated with a point-like light source, in particular when viewed in a dark space with a flashlight of a smartphone. The observer perceives repeated characters "PL" and linear square boundaries that appear bright blue in front of a dark black background.

Fig. 8 shows asecurity element 13 according to the invention according to a third embodiment in cross section. Thesecurity element 13 is based on acarrier film 14, for example a polyethylene terephthalate (PET) film, which in the present example forms the outer layer of thesecurity element 13. A translucentfunctional layer 15 is arranged on the inside of thecarrier film 14. The translucentfunctional layer 15 can be obtained by means of vapor deposition and has a structure with two translucent Al layers and SiO arranged between the two translucent Al layers₂ A multilayer structure of layers. The translucentfunctional layer 15 appears golden when viewed in reflected light and blue in hue when viewed in transmitted light. The translucentfunctional layer 15 is provided on the side opposite thecarrier film 14 with an optional transparent intermediate layer 16, for example an intermediate lacquer, which supports the translucentfunctional layer 15. The optional intermediate layer 16 hasopaque areas 17, whichopaque areas 17 can be obtained, for example, by printing with black printing ink. Theopaque regions 17 may alternatively be provided by means of a structured metallization layer. Structured metallization layers can be obtained, for example, by full-area metallization and subsequent demetallization by a rinsing process or by full-area metallization and subsequent demetallization by a laser. Theopaque region 17 forms a dark background surrounding the linear edges of the character "PL" and the square shown in figure 4. Furthermore, thesecurity element 13 has anembossing lacquer layer 18. Theembossing lacquer layer 18 is based on a UV lacquer in which reflective microstructures, such as ribs of retroreflective structures, are embossed. The relief of theembossing lacquer layer 18 is provided with a specularlyreflective metal coating 19, for example an aluminum metallization layer, in order in this way to form a retroreflective structure together with the relief of the embossing lacquer layer 18.Adjacent to the specularlyreflective metal coating 19, there is arranged, for example, anadhesive layer 20 suitable for mounting thesecurity element 13 on a document of value substrate, for example a banknote.

Fig. 5 and 6 show schematic diagrams for explaining the functional principle of the solution according to the invention.

FIG. 5 shows a translucentfunctional layer 21 that can be obtained by means of vapor deposition and a translucent functional layer having two translucent Al layers and an SiO layer arranged between the two translucent Al layers₂ Multilayer structure of layers (so-called fabry-perot thin layer structure). The translucentfunctional layer 21 appears golden when viewed in reflected light and blue in hue when viewed in transmitted light.Reference numeral 22 denotes incident white light. Due to the translucent golden blue filter, the blue part of the color spectrum is transmitted (see arrow withreference 24, which indicates transmitted blue light). The complementary part, that is to say the golden part, is reflected (see arrow withreference number 23, which indicates the light reflected, that is to say the golden light).

Fig. 6 shows a combination of a translucentfunctional layer 21 known from fig. 5 and aretroreflector 25, which retroreflector 25 is, for example, a microprism known from fig. 1, 2 and 8, which microprism is provided with a specularly reflective metal coating. In the combination by thecolor filter 21 and the retro-reflector 25, the blue, transmittedcolor part 24 of the spectrum is reflected by the retro-reflector 25 and is transmitted again through the gold blue color filter 21 (see dashed arrows withreference numbers 26 and 27, which respectively represent blue light). Blue light 27 can be perceived by the observer, in the case of the example according to fig. 4 in the form of the bright blue letter "PL" and the linear square edges.

The security element shown in fig. 1, 2 and 8 can be supplemented, if desired, by at least one further layer, for example with an embossed structure, such as a micro-mirror structure, or a scattering structure or a diffractive structure. The security element is thus realized, for example, on the basis of the micromirror technology known from the prior art, which does not impair the colored retroreflection at night. The scattering structure can ensure that the golden light part is scattered when vertical light is incident at night.

Fig. 7 shows asecurity element 28 according to the invention according to a fourth embodiment in a cross-sectional view. Thesecurity element 28 is based on acarrier film 29, for example a polyethylene terephthalate (PET) film, which is provided with a translucentfunctional layer 31 on the side facing the viewer. The translucentfunctional layer 31 can be obtained by means of vapor deposition and has a structure with two translucent Al layers and SiO arranged between the two translucent Al layers₂ A multilayer structure of layers. The translucentfunctional layer 31 appears golden when viewed in reflected light and blue in hue when viewed in transmitted light. A translucentfunctional layer 31 is arranged on thecarrier film 29 by means of anembossing lacquer layer 30. Theembossing lacquer layer 30 is based on UV lacquer and has embossed ribs with a microstructure. The translucent functional layer is adapted to the relief such that an observer, when viewing the security element in reflected light, can perceive additional information in the form of patterns, characters and codes which are optically variable according to the viewing angle. The translucentfunctional layer 31 is provided with an optional transparentprotective layer 32, for example a protective lacquer. Thecarrier film 29 has an embossing lacquer layer 33 on the side opposite the translucentfunctional layer 31. The embossing lacquer layer 33 is based on a UV lacquer in which reflective microstructures, for example, ribs of a retroreflective structure, are embossed. The relief of the embossing lacquer layer 33 is provided with a specularlyreflective metal coating 34, for example an aluminum metallization layer, in order to form a retroreflective structure in this way together with the relief of the embossing lacquer layer 33. Adjacent to the specularly reflective metal coating, an adhesive layer 35 is arranged, for example, suitable for the arrangement of theretroreflective film 28 on a document of value, for example a banknote.

FIG. 9 illustrates an embodiment of a retroreflective structure in a top view. Retroreflectors are based on cube corner or microprism structures, in which the incident light is deflected by approximately 45 ° in each case at three mutually oblique interfaces and is reflected back to the light source. Fig. 9 shows the geometry of an embossed retroreflector with triangular facets. The surface of the relief structure may be specularly reflective with a reflective metal layer.

Fig. 10 illustrates other embodiments of retroreflective structures in a top view. The geometry of the embossed retroreflector has a square face.

Fig. 1, 2, 6, 7 and 8 show embodiments in which the reflective microstructures are constructed in the form of retroreflective structures. The reflective microstructure can alternatively be produced as an inlay (Mosaik) consisting of a plurality of reflective inlay elements which are designed in such a way that the markings in the form of patterns, characters or codes have a dynamic shifting effect when the security element is tilted in such a way that the individual groups of inlay elements having different characteristic parameters reflect the reflected light into different spatial regions. For example theridge 5 shown in fig. 1, theridge 11 shown in fig. 2, theridge 25 shown in fig. 6, theridge 34 shown in fig. 7 or theridge 19 shown in fig. 8, respectively, have the appearance of theridge 31 shown in fig. 7, i.e. are identical, different or at least partially identical to theridge 31.

Fig. 11 shows an embodiment of a security element according to the invention suitable for protecting a motor vehicle license plate provided with retroreflective structures. Thesecurity element 21 is based on acarrier film 22, for example a polyethylene terephthalate (PET) film, which in the present example forms the outer layer of thesecurity element 21. A translucentfunctional layer 23 is arranged on the inside of thecarrier film 22. The translucentfunctional layer 23 can be obtained by means of vapor deposition and has a structure with two translucent Al layers and SiO arranged between the two translucent Al layers₂ A multilayer structure of layers. The translucentfunctional layer 23 appears golden when viewed in reflected light and blue in hue when viewed in transmitted light. The translucentfunctional layer 23 is provided on the side opposite thecarrier film 22 with an optional transparentintermediate layer 24, for example an intermediate lacquer, which supports the translucentfunctional layer 23. An opaque region is indicated byreference numeral 25, which can be obtained, for example, by printing with black printing ink. Theopaque regions 25 may alternatively be provided by means of a structured metallization layer. Structured metallization layers can be obtained, for example, by full-area metallization and subsequent demetallization by means of a rinsing process, or by full-area metallization and subsequent demetallization by means of a laser. Theopaque area 25 represents, for example, a character, a pattern, or a code. Furthermore, thesecurity element 21 has anadhesive layer 26.

The license plate or number plate of the motor vehicle protected by thesecurity element 21 is denoted byreference numeral 27. Thelicense plate 27 has aretroreflective structure 28 on the side opposite thesecurity element 21.

Claims (34)

1. A security element for protecting a value document, security document or value item, having predetermined regions which appear in a first visually perceptible color to an observer in diffuse illumination and in a second visually perceptible color when illuminated with punctiform light sources and form an indicium in the form of a pattern, a character or a code which is not visible to the observer in diffuse illumination and is only visible when illuminated with punctiform light sources, wherein the security element comprises a layer having a reflective microstructure and a translucent functional layer facing the observer and which is designed such that the translucent functional layer has the first visually perceptible color when viewed in reflected light and the second visually perceptible color when viewed in transmitted light,

wherein the reflective microstructures are configured as retroreflective structures having triangular or tetragonal cube corners or as retroreflective structures based on microglass beads, wherein the retroreflective structures are provided with a metallized layer,

wherein the indicia in the form of patterns, characters or codes are formed by recesses in an opaque layer arranged between a translucent functional layer and the layer having the retroreflective structure, wherein the opaque layer is a metallized layer or a color layer.

2. The security element of claim 1, wherein the diffuse illumination is when viewed in daylight.

3. The security element of claim 1, wherein illumination with a point-like light source is a situation when viewed in a dark space with a flashlight of a smartphone.

4. A security element according to claim 1, wherein the retroreflective structure is provided with a specularly reflective metal coating.

5. A security element according to claim 1, wherein the reflective microstructures are constituted in the form of an inlay consisting of a plurality of reflective inlay elements, which are characterized by the parameters size, profile shape, relief shape, reflectivity and spatial orientation, and which are constituted such that indicia in the form of patterns, characters or codes have a dynamic shifting effect when the security element is tilted, in such a way that each set of inlay elements with different characteristic parameters reflects incident light into different spatial regions.

6. A security element according to claim 1, wherein the layer with the reflective microstructure is present in the form of a metallised embossing lacquer layer.

7. A security element according to claim 5 wherein the indentations in the opaque layer form first indicia in the form of a pattern, character or code and the reflective microstructures form second indicia in the form of a pattern, character or code in the form of an inlay of a plurality of reflective tessellating elements, wherein the second indicia at least partially conforms to the first indicia.

8. The security element according to claim 1, wherein the translucent functional layer has a multilayer structure with two translucent metal layers and a dielectric layer arranged between the two translucent metal layers.

9. Security element according to claim 8, wherein the two translucent metal layers are formed independently of one another by metals, and the metals are each selected from the elements Al, Ag, Ni, Cr, Cu, Au, Si and alloys of at least one of the aforementioned elements, and the dielectric layer is SiO₂ Layer, ZnO layer, ZnS layer, Al₂ O₃ Layer, TiO₂ A layer, a layer composed of a nitride or oxynitride of Si, Zn, Al or Ti, or MgF₂ A layer or a nitrocellulose layer.

10. Security element according to claim 8, wherein the two semi-transparent metal layers are selected independently of one another from Al or Ag and the dielectric layer is SiO₂ And (3) a layer.

11. The security element according to claim 1, wherein the translucent functional layer is obtainable in printing technology by means of an effect pigment composition.

12. The security element according to claim 1, wherein the translucent functional layer has a multilayer structure based on an interference layer consisting of only transparent layers, wherein the multilayer structure is based on a material consisting of TiO₂ 、Al₂ O₃ Or layers of other dielectrics.

13. The security element according to claim 1, wherein the semi-transparent functional layer is based on a plasmonic color filter and on two-dimensional periodic nanostructures.

14. The security element according to claim 1, wherein the predetermined areas appear golden to a viewer when illuminated diffusely and blue tones when illuminated with a point-like light source.

15. The security element of claim 1, wherein the security element has the following structure:

-an adhesive layer;

-a layer having reflective microstructures;

-an opaque layer having a hollow in the form of a pattern, character or code;

-a translucent functional layer;

-a carrier film.

16. The security element of claim 1, wherein the security element has the following structure:

-an adhesive layer;

-a layer having reflective microstructures;

-a carrier film;

-a translucent functional layer;

wherein an opaque layer having recesses in the form of patterns, characters or codings is arranged between the layer having the reflective microstructure and the carrier film or between the carrier film and the translucent functional layer.

17. A security element according to claim 15 or 16, wherein an embossing lacquer layer having an embossing relief is arranged between the carrier film and the translucent functional layer, wherein the embossing relief is a relief having a microstructure and/or a nanostructure.

18. A data carrier comprising a security element according to one of claims 1 to 17.

19. A data carrier according to claim 18, wherein the data carrier is a value document, a security document or an item of value.

20. Security element for protecting a data carrier provided with a retroreflective structure, wherein the security element has a predetermined area which, when illuminated diffusely, appears to an observer in a first visually perceptible color and, when illuminated with punctiform light sources, appears in a second visually perceptible color, and wherein the predetermined area forms a marking in the form of a pattern, a character or a code which is not visible to the observer when illuminated diffusely and is only visible when illuminated with punctiform light sources, wherein the security element comprises an adhesive layer suitable for adhering the security element to the data carrier provided with retroreflective structure to be protected and a translucent functional layer facing the observer, and wherein the translucent functional layer is designed such that the translucent functional layer has the first visually perceptible color when viewed in reflected light and the second visually perceptible color when viewed in transmitted light The color of (a) is selected,

wherein the marking in the form of a pattern, character or code is formed by a recess in an opaque layer arranged between the translucent functional layer and the adhesive layer.

21. The security element of claim 20, wherein the diffuse illumination is when viewed in daylight.

22. The security element of claim 20, wherein illumination with a point-like light source is a situation when viewed in a dark space with a flashlight of a smartphone.

23. The security element according to claim 20, wherein the translucent functional layer has a multilayer structure with two translucent metal layers and a dielectric layer arranged between the two translucent metal layers.

24. Security element according to claim 23, wherein the two translucent metal layers are formed independently of one another from a metal, and the metal is selected from the elements Al, Ag, Ni, Cr, Cu, Au, Si and alloys of at least one of the aforementioned elements, respectively, and the dielectric layer is SiO₂ Layer, ZnO layer, ZnS layer, Al₂ O₃ Layer, TiO₂ A layer, a layer composed of a nitride or oxynitride of Si, Zn, Al or Ti, or MgF₂ A layer or a nitrocellulose layer.

25. Security element according to claim 23, wherein the two semi-transparent metal layers are selected independently of each other from Al or Ag and the dielectric layer is SiO₂ And (3) a layer.

26. The security element according to claim 20, wherein the translucent functional layer is obtainable in printing technology by means of an effect pigment composition.

27. The security element according to claim 20, wherein the translucent functional layer has a multilayer structure based on an interference layer consisting of only transparent layers, wherein the multilayer structure is based on a material consisting of TiO₂ 、Al₂ O₃ Or layers of other dielectrics.

28. The security element according to claim 20, wherein the semi-transparent functional layer is based on a plasmonic color filter and on two-dimensional periodic nanostructures.

29. The security element of claim 20 wherein the predetermined regions appear golden to a viewer when illuminated diffusely and blue tones when illuminated with a point-like light source.

30. The security element of claim 20, wherein the security element has the structure:

-an adhesive layer;

-an opaque layer having a recess in the form of a pattern, character or code;

-a translucent functional layer;

-a carrier film.

31. A data carrier provided with a retroreflective structure, comprising a security element according to one of claims 20 to 30.

32. A data carrier as claimed in claim 31, wherein the data carrier is a license plate, a traffic sign, an advertisement board or a safety garment.

33. Use of a security element according to one of claims 20 to 30 for protecting a data carrier provided with a retroreflective structure.

34. The use according to claim 33, wherein the data carrier is a license plate, a traffic sign, an advertisement board or a safety garment.

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