DE102018003602A1 - Retroreflective sheeting, foil, media and use - Google Patents

Abstract

The invention relates to a retroreflective sheeting having predetermined areas which appear to the viewer in diffuse reflection, especially when viewed in daylight, in a first visually recognizable color and appear in retroreflection, especially when viewed at night in the spotlight, in a second visually recognizable color comprising a layer of retroreflective structures and a viewer-facing semi-transparent functional layer adapted to have the first visually recognizable color when viewed in incident light and having the second visually detectable color when viewed in transmitted light.

Description

The invention relates to a retroreflective sheeting and its use. The invention further relates to a film, the use thereof and a data carrier secured by the film.

A retroreflector is a reflective material that reflects incident radiation substantially independently of the orientation of the reflector in the direction back to the radiation source. In other words, the light beam is always reflected back to the source regardless of the angle of incidence. In road traffic, retroreflectors on traffic panels or on vehicles increase their visibility at night in the spotlight. Retroreflectors are usually based on an embossed aluminum foil, on a backside embossed plastic film or on a material containing transparent, retroreflective beads.

Retroreflexionselemente are based in particular on plano-optical angle reflectors or on rotationally symmetrical lens reflectors. In the case of retroreflectors made of plane mirrors or plane surfaces, a distinction is made between designs with two or three mutually perpendicular reflecting planes. With three mirrors one speaks of a triple mirror. A triple prism is a glass body, which is flat at the front and on the back has three non-mirrored plane surfaces standing at an angle of 90 ° to each other. Lens reflectors are based on the fact that the reflected light is directed back in the direction of the light source in the case of an imaging optics with a reflective surface in focus. The optically effective component of reflector films and screens is often based on many small transparent spheres. A translucent sphere of glass or plastic focuses much of the incident light from a far-flung light source onto a spot just behind the back surface. Due to the difference in the refractive index compared to the air, the back surface of the sphere is reflective. Since it is only slightly in front of the focus, the light is directed into a narrow cone around the direction of the light source. Lüneburg lenses are backside mirrored spheres made of a transparent material with an inwardly decreasing refractive index.

The reflector films available on the market are usually based on retroreflective glass spheres or embossed structures, in particular microprisms which are provided with a reflective metal coating or are based on total reflection at the dielectric-air interface. Both variants reflect white light back to the light source as white light, i. neither do they act as color filters, nor is the light split into spectral colors. Viewed under diffuse light, the intrinsic color of the glass sphere reflector film is white, while the embossed retroreflectors usually show a metallic appearance.

For the different fields of use of reflector films, e.g. License plates, traffic signs, security apparel, and retroreflective billboards, different colors are desired. For obtaining colored reflector films it is e.g. It is known to print reflector films with opaque colors in a grid pattern, so that the films appear under diffuse illumination, especially when viewed from a distance, in the color of the printing ink, while in retroreflection they are still perceived as white. According to one variant, reflector films are overprinted over the entire surface with translucent colors, so that they appear in diffuse illumination as well as in retroreflection in the color of the glaze. According to a further variant, a reflector film can be coated over its entire surface with a transparent lacquer with pigment particles contained therein, e.g. Soot, to be printed. In this way, a film can be achieved, which appears black in diffused light and appears in retroreflection white. In other words, diffused light is absorbed to a high degree by the pigment particles, while the high intensity is only partly and not wavelength selectively absorbed in retroreflected light.

The reflector films known in the prior art thus exhibit no color change, let alone a colorful change in color, upon the change of viewing with diffuse reflection, in particular when viewed in daylight, on the one hand and in retroreflection, in particular when viewed at night in the spotlight.

The present invention has the general object to increase the attractiveness of the reflector films.

The object is achieved by the feature combinations defined in the independent claims. Further developments of the invention are the subject of the dependent claims.

Summary of the invention

1. 1. (First aspect of the invention) Retroreflective sheeting with predetermined areas which appear to the observer in diffuse reflection, in particular when viewed in daylight, in a first visually recognizable color and in retroreflection, in particular when viewed at night in the spotlight, in a second visually recognizable color, comprising a layer with retroreflective structures and a viewer facing semi-transparent functional layer, the so is that it has the first visually recognizable color when viewed in reflected light and has the second visually recognizable color when viewed in transmitted light. The retroreflective structures are preferably selected from retroreflective glass spheres or embossed structures. In particular, it is preferred that the retroreflective structures be based on microprisms provided with a metallization, in particular a reflective metal coating.
2. 2. (Preferred Embodiment) Retroreflective sheeting according to clause 1 in which the retroreflective structures are based on triangular or quadrangular cube corners or on micro glass beads and in particular are metallised.
3. 3. (Preferred Embodiment) Retroreflective sheeting according to clause 1 or 2 in which the semitransparent functional layer has a multilayer structure with two semitransparent metallic layers and a dielectric layer arranged between the two semitransparent metallic layers.
4. 4. (Preferred Embodiment) Retroreflective sheeting according to clause 3 wherein the two semitransparent metallic layers are independently formed of a metal and the metal is selected from the group consisting of Al, Ag, Ni, Cr, Cu, Au, Si and an alloy of one or more of the aforementioned elements; dielectric layer is an SiO ₂ layer, a ZnO layer, a ZnS layer, an Al ₂ O ₃ layer, a TiO ₂ layer, a layer of a nitride or oxynitride of any of Si, Zn, Al or Ti or a MgF ₂ layer or, for example, technically available, nitrocellulose layer.
5. 5. (Preferred Embodiment) Retroreflective sheeting according to clause 3 or 4 wherein the two semitransparent metallic layers are independently selected from Al or Ag and the dielectric layer is an SiO ₂ layer.
6. 6. (Preferred Embodiment) Retroreflective sheeting according to clause 1 or 2 , wherein the semitransparent functional layer is obtainable by printing technology by means of an effect pigment composition.
7. 7. (Preferred Embodiment) Retroreflective sheeting according to clause 1 or 2 , wherein the semitransparent functional layer has a multilayer structure based on interference layers consisting only of transparent layers, wherein the multilayer structure is based in particular on, preferably alternating, layers of TiO ₂ , Al ₂ O ₃ or other dielectrics.
8. 8. (Preferred Embodiment) Retroreflective sheeting according to clause 1 or 2 wherein the semitransparent functional layer is based on a plasmonic color filter and in particular based on two-dimensional periodic nanostructures. Plasmonic color filters based on two-dimensional periodic nanostructures are known, for example, from US Pat DE 10 2011101 635 A1 known.
9. 9. (Preferred Embodiment) Retroreflective sheeting according to one of the clauses 1 to 8th In the case of diffuse reflection, in particular when viewed in daylight, the predetermined regions appear golden to the viewer and appear bluish in retroreflection, especially when viewed at night in the spotlight.
10. 10. (Preferred Embodiment) Retroreflective sheeting according to one of the clauses 1 to 9 , wherein the predetermined areas markings in the form of patterns, characters or a coding form, which are not recognizable to the viewer in diffuse reflection, especially when viewed in daylight, and only in retroreflection, especially when viewed at night in the spotlight, are recognizable ,
11. 11. (Preferred Embodiment) Retroreflective sheeting according to clause 10 in which the markings are formed in the form of patterns, characters or a coding by recesses in an opaque layer which is arranged between the semitransparent functional layer and the layer with the retroreflective structures, the opaque layer being in particular a metallization or a color layer.
12. 12. (Preferred Embodiment) Retroreflective sheeting according to one of the clauses 1 to 11 wherein the film has the following structure:
    • - adhesive layer;
    • - layer with retroreflective structures;
    • Optionally, an opaque layer with recesses in the form of patterns, characters or an encoding;
    • - semitransparent functional layer;
    • - Carrier film.
13. 13. (Preferred Embodiment) Retroreflective sheeting according to one of the clauses 1 to 12 wherein the film has the following structure:
    • - adhesive layer;
    • - layer with retroreflective structures;
    • - Carrier film;
    • - semitransparent functional layer;
    wherein either an opaque layer with recesses in the form of patterns, characters or an encoding is optionally arranged either between the layer with retroreflective structures and the carrier film or between the carrier film and the semitransparent functional layer.
14. 14. (Preferred Embodiment) Retroreflective sheeting according to clause 12 or 13 in which an embossing lacquer layer with an embossed relief is arranged between the carrier foil and the semitransparent functional layer, wherein the embossed relief is in particular a relief having micro and / or nanostructures.
15. 15. (Second aspect of the invention) Use of the retroreflective sheeting according to one of the clauses 1 to 14 for the production of number plates or license plates, traffic signs or traffic signs, billboards or advertising space, or safety clothing.
16. 16. (Third aspect of the invention) A film for securing a data carrier provided with a retroreflective structure, wherein the film has predetermined areas which appear to the observer in diffuse reflection, in particular when viewed in daylight, in a first visually recognizable color and in retroreflection , especially when viewed at night in the spotlight, appear in a second visually recognizable color and preferably form markings in the form of patterns, characters or a coding, which are not recognizable to the viewer with diffuse reflection, especially when viewed in daylight, and only in retroreflection, in particular when viewed at night in the spotlight, can be seen, the film u a suitable adhesive layer for bonding the film with the protected, provided with a retroreflective structure data carrier and a viewer facing semi-transparent functional layer u mfasst and the semitransparent functional layer is such that it has the first visually recognizable color when viewed in reflected light and has the second visually recognizable color when viewed in transmitted light. It is preferred that the retroreflective structure of the data carrier is based on a reflective microstructure, in particular in the form of a retroreflective structure with triangular or square cube corners, or in the form of a microglass-based retroreflective structure, the reflective microstructure preferably having a metallization preferably provided with a reflective metal coating.
17. 17. (Preferred embodiment) Slide after clause 16 , wherein the predetermined areas form markings in the form of patterns, characters or a coding, which are not recognizable to the viewer in diffuse reflection, especially when viewed in daylight, and are only recognizable by retroreflection, especially when viewed at night in the spotlight , and the markings are formed in the form of patterns, characters or a coding by recesses in an opaque layer, which is arranged between the semitransparent functional layer and the adhesive layer.
18. 18. (Preferred Embodiment) Foil according to one of the clauses 16 or 17 in which the semitransparent functional layer has a multilayer structure with two semitransparent metallic layers and a dielectric layer arranged between the two semitransparent metallic layers.
19. 19. (Preferred embodiment) Slide according to clause 18 wherein the two semitransparent metallic layers are independently formed of a metal and the metal is selected from the group consisting of Al, Ag, Ni, Cr, Cu, Au, Si and an alloy of one or more of the aforementioned elements; dielectric layer is an SiO ₂ layer, a ZnO layer, a ZnS layer, an Al ₂ O ₃ layer, a TiO ₂ layer, a layer of a nitride or oxynitride of any of Si, Zn, Al or Ti or a MgF ₂ layer or, for example, technically available, nitrocellulose layer.
20. 20. (Preferred embodiment) Slide according to clause 18 or 19 wherein the two semitransparent metallic layers are independently selected from Al or Ag and the dielectric layer is an SiO ₂ layer.
21. 21. (Preferred Embodiment) Foil according to one of the clauses 1 to 6 , wherein the semitransparent functional layer is obtainable by printing technology by means of an effect pigment composition.
22. 22. (Preferred Embodiment) Film according to one of the clauses 16 or 17 in which the semitransparent functional layer has a multilayer structure based on interference layers consisting only of transparent layers, the multilayer structure being particularly preferred alternating, layers of TiO ₂ , Al ₂ O ₃ or other dielectrics based.
23. 23. (Preferred Embodiment) Foil according to one of the clauses 16 or 17 wherein the semitransparent functional layer is based on a plasmonic color filter and in particular based on two-dimensional periodic nanostructures. Plasmonic color filters based on two-dimensional periodic nanostructures are known, for example, from US Pat DE 10 2011101 635 A1 known.
24. 24. (Preferred embodiment) Foil according to one of the clauses 16 to 23 In the case of diffuse illumination, in particular when viewed in daylight, the predetermined areas appear golden to the observer and appear bluish when illuminated with a punctiform light source, in particular when viewed with the flashlight of a smartphone in a darkened room.
25. 25. (Preferred Embodiment) Film according to one of the clauses 16 to 24 wherein the film has the following structure:
    • - adhesive layer;
    • Optionally, an opaque layer with recesses in the form of patterns, characters or an encoding;
    • - semitransparent functional layer;
    • - Carrier film.
26. 26. (Fourth aspect of the invention) A data carrier provided with a retroreflective structure, in particular a license plate, a road sign, a billboard, or safety clothing, comprising the film according to one of the clauses 16 to 25 ,
27. 27. (Fifth Aspect of the Invention) Use of the film according to one of the clauses 16 to 25 for securing a data carrier provided with a retroreflective structure, in particular a license plate, a road sign, a billboard or advertising space, or safety clothing.

Detailed description of the invention

An observation in reflected light in the sense of this invention is a lighting of the respective object from one side and a viewing of the object from the same side.

A reflection in the transmitted light in the sense of this invention is an illumination of the respective object from one side and a viewing of the object from the opposite side.

Daylight is here termed diffused daylight or simply simply diffused light, which illuminates the scene evenly and with little or no shadow. Diffused light is produced by areal light sources.

In accordance with the present invention, there are provided attractive reflector films which, on the other hand, exhibit an interesting color change upon the change of viewing in diffuse reflection, especially when viewed in daylight, on the one hand, and retroreflective, especially at night in the spotlight, e.g. a color change from gold in daylight to blue at night in spot light. Incidentally, the same appearance as when viewed at night in the spotlight provides the viewer when viewing a photograph taken with a smartphone camera with the flash on.

Retroreflective structures that reflect the light from vehicle headlights toward the vehicle operator to increase visibility are known in the art and may be based, for example, on triangular or quadrangular cube corners or on micro-glass beads, see for example the documents US 4763985 A . US 20090300953 A1 . WO 2014/117086 A1 . US 6413615 B2 and US 4478769 A , Cube-corner structures are based, for example, on embossed relief structures that are mirrored with a reflective metal layer. The cube-corner structures may be present in particular with triangular or quadrilateral surfaces. Conveniently, the relief structures are embossed in a plastic material or in a UV varnish.

The retroreflective sheeting of the present invention is suitably provided based on a carrier sheet such as polyethylene terephthalate (PET), polymethyl methacrylate (PMMA), polypropylene (PP), polyethylene (PE), polycarbonate (PC), polyvinyl butyral (PVB), polyvinyl chloride (PVC) or the like.

The layer comprising the retroreflective structures may suitably be present in a layer thickness in a range of 10 μm to 200 μm, preferably in a range of 30 μm to 150 μm and particularly preferably in a range of 40 μm to 150 μm. The height of the retroreflective structures, in particular of the triangular or quadrangular cube corners, is expediently at least 10 μm, preferably at least 30 μm, and expediently less than 200 μm, preferably less than 150 μm.

The semitransparent functional layer, on the other hand, has different hues when viewed in reflected light on the one hand and when viewed in transmitted light on the other hand. The two different shades are, for example, complementary colors. Such a semitransparent functional layer is in particular a so-called Fabry-Perot thin-film element based on a multilayer construction with two semitransparent metallic layers and a dielectric layer arranged between the two semitransparent metallic layers. Such a multi-layered structure, which appears golden when viewed in reflected light and shows a blue hue when viewed in transmitted light, is for example from the WO 2011/082761 A1 known.

• - die beiden semitransparenten metallischen Schichten werden bevorzugt von Al oder Ag gewählt; die dielektrische Schicht ist insbesondere eine SiO₂-Schicht oder eine MgF₂-Schicht, bevorzugt eine SiO₂-Schicht;
• - im Falle, dass jede der beiden semitransparenten metallischen Schichten auf Al beruht, liegt die jeweilige bevorzugte Schichtdicke in einem Bereich von 5 nm bis 20 nm, insbesondere bevorzugt in einem Bereich von 10 nm bis 14 nm; die dielektrische SiO₂-Schicht hat vorzugsweise eine Schichtdicke in einem Bereich von 50 nm bis 600 nm, weiter bevorzugt in einem Bereich von 80 nm bis 260 nm und insbesondere bevorzugt in einem Bereich von 210 nm bis 260 nm, wobei die Bereiche von 80 nm bis 100 nm und von 210 nm bis 240 nm speziell für die Bereitstellung eines Gold/Blau-Farbwechsels besonders bevorzugt werden;
• - im Falle, dass jede der beiden semitransparenten metallischen Schichten auf Ag beruht, liegt die jeweilige bevorzugte Schichtdicke in einem Bereich von 15 nm bis 30 nm, insbesondere bevorzugt von 15 nm bis 25 nm; die dielektrische SiO₂-Schicht hat vorzugsweise eine Schichtdicke in einem Bereich von 50 nm bis 600 nm, weiter bevorzugt in einem Bereich von 80 nm bis 260 nm und insbesondere bevorzugt in einem Bereich von 210 nm bis 260 nm, wobei die Bereiche von 80 nm bis 100 nm und von 210 nm bis 240 nm speziell für die Bereitstellung eines Gold/Blau-Farbwechsels besonders bevorzugt werden.

Suitable multilayer structures having two semi-transparent metallic layers and a dielectric layer arranged between the two semitransparent metallic layers preferably have the following physical properties:

• the two semitransparent metallic layers are preferably selected from Al or Ag; the dielectric layer is in particular an SiO ₂ layer or an MgF ₂ layer, preferably an SiO ₂ layer;
• in the case where each of the two semitransparent metallic layers is based on Al, the respective preferred layer thickness is in a range of 5 nm to 20 nm, particularly preferably in a range of 10 nm to 14 nm; the dielectric SiO ₂ layer preferably has a layer thickness in a range of 50 nm to 600 nm, more preferably in a range of 80 nm to 260 nm and particularly preferably in a range of 210 nm to 260 nm, the ranges of 80 nm up to 100 nm and from 210 nm to 240 nm are especially preferred for providing a gold / blue color change;
• in the case where each of the two semitransparent metallic layers is based on Ag, the respective preferred layer thickness is in a range from 15 nm to 30 nm, particularly preferably from 15 nm to 25 nm; the dielectric SiO ₂ layer preferably has a layer thickness in a range of 50 nm to 600 nm, more preferably in a range of 80 nm to 260 nm and particularly preferably in a range of 210 nm to 260 nm, the ranges of 80 nm to 100 nm and from 210 nm to 240 nm are especially preferred for providing a gold / blue color change.

• - ein Silber/ Dielektrikum/ Aluminium-Schichtsystem, wobei die Schichtdicken der Silber-Schicht und der Aluminium-Schicht identisch oder verschieden sind;
• - ein Silber/Dielektrikum/Silber-Schichtsystem, wobei die Schichtdicken der beiden Silber-Schichten verschieden sind;
• - ein Aluminium/ Dielektrikum/ Aluminium-Schichtsystem, wobei die Schichtdicken der beiden Aluminium-Schichten verschieden sind.

The above-mentioned multilayer structures having two semi-transparent metallic layers and a dielectric layer disposed between the two semitransparent metallic layers may have a symmetrical three-layer structure in which both the material and the layer thickness of the two semitransparent metallic layers are identical. Alternatively, however, there may also be an asymmetrical three-layer structure in which the material and / or the layer thickness of the two semitransparent metallic layers are different, eg

• a silver / dielectric / aluminum layer system, wherein the layer thicknesses of the silver layer and the aluminum 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.

• - im Auflicht Magenta, im Durchlicht Blau-Grün;
• - im Auflicht Türkis, im Durchlicht Orange-Gelb;
• - im Auflicht Gold, im Durchlicht Blau-Violett;
• - im Auflicht Silber, im Durchlicht Violett.

The abovementioned multi-layered layer structures not only make it possible to produce a semitransparent functional layer that appears gold-colored when viewed in reflected light and shows a blue hue when viewed in transmitted light, but further color changes can be produced depending on the choice of the layer thickness, in particular of the dielectric layer, eg

• Magenta in transmitted light, blue-green in transmitted light;
• - in incident light turquoise, in transmitted light orange-yellow;
• - in reflected light gold, in transmitted light blue-violet;
• - in reflected light silver, in transmitted light violet.

A semitransparent functional layer which has different shades when viewed in reflected light on the one hand and when viewed in transmitted light on the other hand, can also be based on an effect pigment composition. Printed layers based on an effect pigment composition which, when viewed in incident light, show a different color than when viewed in transmitted light, in particular a gold / blue color change, a gold / violet color change, a green / gold / magenta color change, a Violet / green color change or a silver / opaque color change, are eg in the WO 2011/064162 A2 described. The pigments preferably have a longest dimension of edge length from end-to-end in a range of 15 nm to 1000 nm and are based on a transition metal selected from the group consisting of Cu, Ag, Au, Zn, Cd, Ti, Cr, Mn, Fe, Co, Ni, Ru, Rh, Pd, Os, Ir and Pt. The transition metal is preferably Ag. The aspect ratio (ie the ratio of the longest end-to-end dimension relative to the thickness) is preferably at least 1, 5, in particular in a range from 1.5 to 300. The ratio of the binder to metal pigment is preferably below 10: 1, in particular below 5: 1. Depending on the choice of aspect ratio of the pigment, its longest end-to-end dimension, and adjustment of the pigment / binder ratio, the color can be seen in transmission and the color when viewed in reflection (eg, blue in Transmission and silver, gold, bronze, copper or violet in reflection, in addition also violet, magenta, pink, green or brown in transmission and different colors in reflection, which depend on the choice of pigment / binder ratio). Colors with gold / blue color change between reflection and transmission (in other words, between incident light and transmitted light observation) are, for example, in Examples 1, 2 and 3 in Table 1 of FIG WO 2011/064162 A2 called. Further, Example 4 shows a color with gold / violet color change, Example 5 a color with green-gold / magenta color change, Example 7 a color with violet / green color change and Example 8 a color with silver / opaque color change.

• - Klebschicht, die z.B. für das Aufbringen der Folie auf ein Kennzeichenschild geeignet ist;
• - Schicht mit retroreflektierenden Strukturen;
• - optional eine opake Schicht mit Aussparungen in Form von Mustern, Zeichen oder einer Codierung;
• - semitransparente Funktionsschicht;
• - Trägerfolie.

The retroreflective sheeting according to the invention expediently has the following structure:

• - adhesive layer, which is suitable for example for applying the film to a license plate;
• - layer with retroreflective structures;
• Optionally, an opaque layer with recesses in the form of patterns, characters or an encoding;
• - semitransparent functional layer;
• - Carrier film.

• - Klebschicht, die z.B. für das Aufbringen der Folie auf ein Kennzeichenschild geeignet ist;
• - Schicht mit retroreflektierenden Strukturen;
• - Trägerfolie;
• - semitransparente Funktionsschicht;
• - optional ein Schutzlack oder eine Schutzfolie, um die semitransparente Funktionsschicht vor schädlichen Umwelteinflüssen zu schützen;

wobei entweder zwischen der Schicht mit retroreflektierenden Strukturen und der Trägerfolie oder zwischen der Trägerfolie und der semitransparenten Funktionsschicht optional eine opake Schicht mit Aussparungen in Form von Mustern, Zeichen oder einer Codierung angeordnet ist.According to a variant, the retroreflective sheeting of the invention may have the following structure:

• - adhesive layer, which is suitable for example for applying the film to a license plate;
• - layer with retroreflective structures;
• - Carrier film;
• - semitransparent functional layer;
• - Optionally, a protective lacquer or a protective film to protect the semi-transparent functional layer from harmful environmental influences;

wherein either an opaque layer with recesses in the form of patterns, characters or an encoding is optionally arranged either between the layer with retroreflective structures and the carrier film or between the carrier film and the semitransparent functional layer.

The opaque layer may in particular be a metallization obtainable, for example, by vapor deposition or a color layer obtainable, for example, by means of a printing process. The production of structured metallizations by means of a washing process is known in the art, see for example the document EP 1972462 B1 and the prior art cited therein. To produce the color layer, platelet-shaped metal pigments may furthermore be used, for example from the publications 2013/186167 A2, US Pat. WO 2010/069823 A1 . WO 2005/051675 A2 (See, for example, the description on page 11, line 10, to page 12, penultimate paragraph) and WO 2011/064162 A2 are known. The platelet-shaped metal pigments described therein have the advantage that they conform to a substrate having a relief structure, in particular a relief with microstructures and / or nanostructures, so well that the difference to a conventional metallization obtainable by vapor deposition is almost no longer recognizable. The simple, printing-technical production of the reflection layer makes it possible to dispense with complex process steps, such as printing the carrier with a soluble wash in the form of a desired recess within the reflection layer to be produced, generating a metallization by vapor deposition and washing the washing paint together with the above the washing paint applied metallization.

Between the carrier film and the semitransparent functional layer it is expediently possible to arrange an embossing lacquer layer with an embossed relief, wherein the embossed relief is in particular a relief having micro and / or nanostructures. The semitransparent functional layer adapts to the relief, so that the observer can perceive additional optically variable information, for example in the form of patterns, characters or a coding, when viewing the retroreflective sheeting in reflected light. Optically variable security elements with a microstructure that are suitable for securing banknotes are, for example, from WO 2007/079851 A1 and from the WO 2011/066991 A2 known.

Furthermore, the retroreflective sheeting according to the invention can be overprinted with a translucent varnish which optionally has pigment particles, e.g. black, white or colored pigment particles. Furthermore, the retroreflective sheeting of the invention can be overprinted with a combination of a full-surface glaze and a screened print of an opaque color.

Other embodiments and advantages of the invention will be explained below with reference to the schematically greatly simplified figures, in the representation of a scale and proportional representation was omitted in order to increase the clarity.

• 1 eine erfindungsgemäße retroreflektierende Folie gemäß einem ersten Ausführungsbeispiel in Querschnittansicht;
• 2 eine erfindungsgemäße retroreflektierende Folie gemäß einem zweiten Ausführungsbeispiel in Querschnittansicht;
• 3 eine erfindungsgemäße retroreflektierende Folie gemäß einem dritten Ausführungsbeispiel in Draufsicht bei der Betrachtung im Tageslicht;
• 4 die erfindungsgemäße retroreflektierende Folie gemäß dem dritten Ausführungsbeispiel in Draufsicht bei der Betrachtung nachts im Scheinwerferlicht;
• 5 und 6 Darstellungen zur Erklärung der Funktionsweise des Erfindungsgegenstandes;
• 7 eine erfindungsgemäße retroreflektierende Folie gemäß einem vierten Ausführungsbeispiel in Querschnittansicht;
• 8 die erfindungsgemäße retroreflektierende Folie gemäß dem dritten Ausführungsbeispiel in Querschnittansicht;
• 9 ein Ausführungsbeispiel für eine retroreflektierende Struktur in Draufsicht;
• 10 ein weiteres Ausführungsbeispiel für eine retroreflektierende Struktur in Draufsicht; und
• 11 ein Ausführungsbeispiel einer erfindungsgemäßen Folie, die für das Absichern eines Kraftfahrzeug-Kennzeichens geeignet ist.

Show it:

• 1 a retroreflective sheeting according to a first embodiment according to the invention in cross-sectional view;
• 2 a retroreflective sheeting according to a second embodiment in cross-sectional view;
• 3 a retroreflective sheeting according to a third embodiment of the invention in plan view when viewed in daylight;
• 4 the retroreflective sheeting of the invention according to the third embodiment in plan view when viewed at night in the spotlight;
• 5 and 6 Representations to explain the operation of the subject invention;
• 7 a retroreflective sheeting according to a fourth embodiment of the invention in cross-sectional view;
• 8th the retroreflective sheeting of the invention according to the third embodiment in cross-sectional view;
• 9 an embodiment of a retroreflective structure in plan view;
• 10 a further embodiment of a retroreflective structure in plan view; and
• 11 An embodiment of a film according to the invention, which is suitable for securing a motor vehicle license plate.

The 1 shows a retroreflective sheeting according to the invention 1 according to a first embodiment in cross-sectional view. The retroreflective sheeting 1 based on a carrier foil 2 , For example, a polyethylene terephthalate (PET) film, which is provided on the viewer side facing with a semi-transparent functional layer. The semitransparent functional layer 3 is obtainable by vapor deposition and has a multilayer structure with two semi-transparent Al layers and an SiO ₂ layer arranged between the two semitransparent Al layers. The semitransparent functional layer 3 appears golden when viewed in reflected light and shows a blue hue when viewed in transmitted light. The carrier foil 2 is on the semitransparent functional layer 3 opposite side with an embossing lacquer layer 4 Mistake. The embossing lacquer layer 4 is based, for example, on a UV varnish in which the relief of the retroreflective structures is embossed. The relief of the embossing lacquer layer 4 is with a reflective metal coating 5 , in the example an aluminum metallization, provided in order in this way together with the relief of the embossing lacquer layer 4 to form the retroreflective structures. Adjacent to the reflective metal coating 5 is an adhesive layer 6 arranged, for example, for the application of the retroreflective sheeting 1 is suitable for a license plate.

The 2 shows a retroreflective sheeting according to the invention 7 according to a second embodiment in cross-sectional view. The retroreflective sheeting 7 based on a carrier foil 8th For example, a polyethylene terephthalate (PET) film, which in the present example is an outer layer of the retroreflective sheeting 7 forms. The carrier foil 8th is on its inside with a semitransparent functional layer 9 Mistake. The semitransparent functional layer 9 is obtainable by vapor deposition and has a multilayer structure with two semi-transparent Al layers and an SiO ₂ layer arranged between the two semitransparent Al layers. The semitransparent functional layer 9 appears golden when viewed in reflected light and shows a blue hue when viewed in transmitted light. The semitransparent functional layer 9 is on the carrier film 8th opposite side with an embossing lacquer layer 10 Mistake. The embossing lacquer layer 10 Based on a UV varnish, in which the relief of the retroreflective structures is marked. The relief of the embossing lacquer layer 10 is with a reflective metal coating 11 , in the example an aluminum metallization, provided in order in this way together with the relief of the embossing lacquer layer 10 to form the retroreflective structures. Adjacent to the reflective metal coating 11 is an adhesive layer 12 arranged, for example, for the application of the retroreflective sheeting 1 is suitable for a license plate.

The 3 shows a retroreflective sheeting according to the invention 13 according to a third embodiment in plan view when viewed in daylight. The retroreflective sheeting 13 appears to the viewer in the form of a gold-colored, metallic surface.

The 4 shows the retroreflective sheeting according to the invention 13 according to the third embodiment in plan view when viewed at night in the spotlight (the same appearance is the viewer when looking at a photograph taken with a smartphone camera with the flash). The viewer perceives the repeating characters "PL" and the line-shaped, square border in a bright blue color against a dark, black background.

The 8th shows the retroreflective sheeting according to the invention 13 according to the third embodiment in cross-sectional view. The retroreflective sheeting 13 based on a carrier foil 14 For example, a polyethylene terephthalate (PET) film, which in the present example is an outer layer of the retroreflective sheeting 13 forms. The carrier foil 14 is on its inside with a semitransparent functional layer 15 Mistake. The semitransparent functional layer 15 obtainable by vapor deposition and has a multilayer structure with two semi-transparent Al-layers and one semi-transparent between the two Al layers arranged SiO ₂ layer. The semitransparent functional layer 15 appears golden when viewed in reflected light and shows a blue hue when viewed in transmitted light. The semitransparent functional layer 15 is on the carrier film 8th opposite side with an optional, the semitransparent functional layer 15 protective transparent interlayer 16 , in the example an intermediate coating, provided. The optional intermediate layer 16 has opaque areas 17 on, for example, by printing with a black ink available. Alternatively, the opaque areas 17 be provided by a structured metallization. A structured metallization can be obtained, for example, by full-surface metallization and subsequent demetallization by means of a washing process or by full-surface metallization and subsequent demetallization by means of a laser. The opaque areas 17 put in the 4 illustrated dark background representing the characters " PL "And surrounds the square line-shaped border. Furthermore, the retroreflective sheeting has 13 an embossing lacquer layer 18 on. The embossing lacquer layer 18 Based on a UV varnish, in which the relief of the retroreflective structures is marked. The relief of the embossing lacquer layer 18 is with a reflective metal coating 19 , in the example an aluminum metallization, provided in order in this way together with the relief of the embossing lacquer layer 18 to form the retroreflective structures. Adjacent to the reflective metal coating 19 is an adhesive layer 20 arranged, for example, for the application of the retroreflective sheeting 13 is suitable for a license plate.

5 and 6 show representations to explain the operation of the subject invention.

The 5 shows a semitransparent functional layer 21 , which is obtainable by vapor deposition and has a multilayer structure with two semi-transparent Al layers and an SiO ₂ layer arranged between the two semitransparent Al layers (so-called Fabry-Perot thin-film structure). The semitransparent functional layer 21 appears golden when viewed in reflected light and shows a blue hue when viewed in transmitted light. The reference number 22 refers to the incoming white light. As a result of the semitransparent gold-blue color filter, the blue part of the color spectrum is transmitted (see the arrow with the reference number 24 which denotes the transmitted blue light). The complementary, so to speak gold-colored part is reflected (see the arrow with the reference number 23 which denotes the reflected, so-called golden, light).

The 6 shows the combination of the 5 known, semitransparent functional layer 21 together with retroreflectors 25 , in the example from the 1 . 2 and 8th known microprisms, which are provided with a reflective metal coating. In the combination of color filter 21 together with the retroreflectors 25 becomes the blue, transmitted color component 24 of the light spectrum through the retroreflectors 25 reflected and a second time through the gold-blue color filter 21 transmitted (see the dashed arrows with the reference numbers 26 and 27 each denoting the blue light). the blue light 27 is perceptible to the viewer, in the case of the embodiment according to the 4 in the form of the luminous, blue letters "PL" and the linear, square border.

The in the 1 . 2 and 8th Optionally, the film structure shown may optionally be supplemented by at least one further layer which has, for example, embossed structures such as, for example, micromirror arrangements or scattering structures or diffractive structures. As a result, it is possible, for example, to implement security elements based on the micromirror technology known in the prior art, which does not impair the color retroreflection at night. In the event of a vertical incidence of light at night, scattering structures can cause the gold-colored light component to be scattered.

The 7 shows a retroreflective sheeting according to the invention 28 according to a fourth embodiment in cross-sectional view. The retroreflective sheeting 28 based on a carrier foil 29 , For example, a polyethylene terephthalate (PET) film on the side facing the viewer with a semi-transparent functional layer 31 is provided. The semitransparent functional layer 31 is obtainable by vapor deposition and has a multilayer structure with two semi-transparent Al layers and an SiO ₂ layer arranged between the two semitransparent Al layers. The semitransparent functional layer 31 appears golden when viewed in reflected light and shows a blue hue when viewed in transmitted light. The semitransparent functional layer 31 is by means of an embossing lacquer layer 30 on the carrier foil 29 applied. The embossing lacquer layer 30 based on one UV varnish and has an embossed relief containing microstructures. The semitransparent functional layer adapts to the relief, so that when the retroreflective sheeting is viewed in reflected light, the observer can perceive additional, optically variable, information dependent on the viewing angle in the form of patterns, characters or a coding. The semitransparent functional layer 31 is with an optional, transparent protective layer 32 , eg a protective lacquer. The carrier foil 29 points to the semitransparent functional layer 31 opposite side an embossing lacquer layer 33 on. The embossing lacquer layer 33 Based on a UV varnish, in which the relief of the retroreflective structures is marked. The relief of the embossing lacquer layer 33 is with a reflective metal coating 34 , in the example an aluminum metallization, provided in order in this way together with the relief of the embossing lacquer layer 33 to form the retroreflective structures. Adjacent to the reflective metal coating 34 is an adhesive layer 35 arranged, for example, for the application of the retroreflective sheeting 28 is suitable for a license plate.

The 9 shows an embodiment of a retroreflective structure in plan view. The retroreflectors are based on cube-corner structures or microprism structures in which the incident light is deflected successively at three mutually inclined boundary surfaces by approximately 45 ° and reflected back to the beam source. The 9 shows the geometry of embossed retroreflectors with triangular faces. The surface of the relief structure may be mirrored with a reflective metal layer.

The 10 shows a further embodiment of a retroreflective structure in plan view. Here is a geometry of embossed retroreflectors with square surfaces.

The 11 shows an embodiment of a film according to the invention 21 which is suitable for securing a motor vehicle registration plate provided with a retroreflective structure. The foil 21 based on a carrier foil 22 , For example, a polyethylene terephthalate (PET) film, which in the present example, an outer layer of the film 21 forms. The carrier foil 22 is on its inside with a semitransparent functional layer 23 Mistake. The semitransparent functional layer 23 obtainable by vapor deposition and has a multilayer structure with two semi-transparent Al-layers and one semi-transparent between the two Al layers arranged SiO ₂ layer. The semitransparent functional layer 23 appears golden when viewed in reflected light and shows a blue hue when viewed in transmitted light. The semitransparent functional layer 23 is on the carrier film 22 opposite side with an optional, the semitransparent functional layer 23 protective transparent interlayer 24 , in the example an intermediate coating, provided. With the reference number 25 are opaque areas designated, for example, by printing with a black ink available. Alternatively, the opaque areas 25 be provided by a structured metallization. A structured metallization can be obtained, for example, by full-surface metallization and subsequent demetallization by means of a washing process or by full-surface metallization and subsequent demetallization by means of a laser. The opaque areas 25 represent eg characters, patterns or a coding. Furthermore, the film has 21 an adhesive layer 26 on.

With the reference number 27 is one with the foil 21 marked license plate or license plate of a motor vehicle. The license plate 27 points to the slide 21 opposite side a retroreflective structure 28 on.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102011101635 A1 [0008]
• US 4763985A [0013]
• US 20090300953 A1 [0013]
• WO 2014/117086 A1 [0013]
• US 6413615 B2 [0013]
• US 4478769A [0013]
• WO 2011/082761 A1 [0016]
• WO 2011/064162 A2 [0020, 0023]
• EP 1972462 B1 [0023]
• WO 2010/069823 A1 [0023]
• WO 2005/051675 A2 [0023]
• WO 2007/079851 A1 [0024]
• WO 2011/066991 A2 [0024]

Claims (27)

Retroreflective sheeting having predetermined areas appearing to the viewer in diffuse reflection, especially when viewed in daylight, in a first visually recognizable color and appearing on retroreflective reflection, especially when viewed at night in the spotlight, in a second visually recognizable color comprising a layer with retroreflective structures and a semi-transparent functional layer facing the viewer, which is designed to have the first visually recognizable color when viewed in reflected light and to have the second visually detectable color when viewed in transmitted light. Retroreflective sheeting after Claim 1 in which the retroreflective structures are based on triangular or quadrangular cube corners or on micro glass beads and in particular are metallised. Retroreflective sheeting after Claim 1 or 2 in which the semitransparent functional layer has a multilayer structure with two semitransparent metallic layers and a dielectric layer arranged between the two semitransparent metallic layers. Retroreflective sheeting after Claim 3 wherein the two semitransparent metallic layers are independently formed of a metal and the metal is selected from the group consisting of Al, Ag, Ni, Cr, Cu, Au and an alloy of one or more of the aforementioned elements, and the dielectric layer an SiO ₂ layer, a ZnO layer, an Al ₂ O ₃ layer, a TiO ₂ layer, a layer of a nitride or oxynitride of any of Si, Zn, Al or Ti, or a MgF ₂ layer or a , For example, technically available, nitrocellulose layer. Retroreflective sheeting after Claim 3 or 4 wherein the two semitransparent metallic layers are independently selected from Al or Ag and the dielectric layer is an SiO ₂ layer. Retroreflective sheeting after Claim 1 or 2 , wherein the semitransparent functional layer is obtainable by printing technology by means of an effect pigment composition. Retroreflective sheeting after Claim 1 or 2 , wherein the semitransparent functional layer has a multilayer structure based on interference layers consisting only of transparent layers, wherein the multilayer structure is based in particular on, preferably alternating, layers of TiO ₂ , Al ₂ O ₃ or other dielectrics. Retroreflective sheeting after Claim 1 or 2 wherein the semitransparent functional layer is based on a plasmonic color filter and in particular based on two-dimensional periodic nanostructures. Plasmonic color filters based on two-dimensionally periodic nanostructures are known, for example, from DE 10 2011101 635 A1. Retroreflective sheeting after one of Claims 1 to 8th In the case of diffuse reflection, in particular when viewed in daylight, the predetermined regions appear golden to the viewer and appear bluish in retroreflection, especially when viewed at night in the spotlight. Retroreflective sheeting after one of Claims 1 to 9 , wherein the predetermined areas markings in the form of patterns, characters or a coding form, which are not recognizable to the viewer in diffuse reflection, especially when viewed in daylight, and only in retroreflection, especially when viewed at night in the spotlight, are recognizable , Retroreflective sheeting after Claim 10 in which the markings are formed in the form of patterns, characters or a coding by recesses in an opaque layer which is arranged between the semitransparent functional layer and the layer with the retroreflective structures, the opaque layer being in particular a metallization or a color layer. Retroreflective sheeting after one of Claims 1 to 11 wherein the film has the following structure: - adhesive layer; - layer with retroreflective structures; - Optionally an opaque layer with recesses in Form of patterns, characters or coding; - semitransparent functional layer; - Carrier film. Retroreflective sheeting after one of Claims 1 to 12 wherein the film has the following structure: - adhesive layer; - layer with retroreflective structures; - Carrier film; - semitransparent functional layer; wherein either an opaque layer with recesses in the form of patterns, characters or an encoding is optionally arranged either between the layer with retroreflective structures and the carrier film or between the carrier film and the semitransparent functional layer. Retroreflective sheeting after Claim 12 or 13 in which an embossing lacquer layer with an embossed relief is arranged between the carrier foil and the semitransparent functional layer, wherein the embossed relief is in particular a relief having micro and / or nanostructures. Use of the retroreflective sheeting of any of Claims 1 to 14 for the production of number plates or license plates, traffic signs or traffic signs, billboards or advertising space, or safety clothing. A film for securing a data carrier provided with a retroreflective structure, wherein the film has predetermined areas which appear to the viewer in diffuse reflection, especially when viewed in daylight, in a first visually recognizable color and in retroreflection, especially when viewed at night in the spotlight appear in a second visually recognizable color and preferably form markings in the form of patterns, characters or a coding, which are not recognizable to the viewer in diffuse reflection, especially when viewed in daylight, and only in retroreflection, especially when viewed at night in the spotlight, can be seen, wherein the film comprises a suitable adhesive layer for bonding the film to the protected, provided with a retroreflective structure data carrier adhesive layer and a viewer facing semi-transparent functional layer and the semitransparent Fun Ctionsschicht is such that it has the first visually recognizable color when viewed in reflected light and has the second visually recognizable color when viewed in transmitted light. Slide after Claim 16 , wherein the predetermined areas form markings in the form of patterns, characters or a coding, which are not recognizable to the viewer in diffuse reflection, especially when viewed in daylight, and are only recognizable by retroreflection, especially when viewed at night in the spotlight , and the markings are formed in the form of patterns, characters or a coding by recesses in an opaque layer, which is arranged between the semitransparent functional layer and the adhesive layer. Foil after one of the Claims 16 or 17 in which the semitransparent functional layer has a multilayer structure with two semitransparent metallic layers and a dielectric layer arranged between the two semitransparent metallic layers. Slide after Claim 18 wherein the two semitransparent metallic layers are independently formed of a metal and the metal is selected from the group consisting of Al, Ag, Ni, Cr, Cu, Au, Si and an alloy of one or more of the aforementioned elements; dielectric layer is an SiO ₂ layer, a ZnO layer, a ZnS layer, an Al ₂ O ₃ layer, a TiO ₂ layer, a layer of a nitride or oxynitride of any of Si, Zn, Al or Ti or a MgF ₂ layer or, for example, technically available, nitrocellulose layer. Slide after Claim 18 or 19 wherein the two semitransparent metallic layers are independently selected from Al or Ag and the dielectric layer is an SiO ₂ layer. Foil after one of the Claims 1 to 6 , wherein the semitransparent functional layer is obtainable by printing technology by means of an effect pigment composition. Foil after one of the Claims 16 or 17 , wherein the semitransparent functional layer has a multilayer structure based on interference layers consisting only of transparent layers, wherein the multilayer structure is based in particular on, preferably alternating, layers of TiO ₂ , Al ₂ O ₃ or other dielectrics. Foil after one of the Claims 16 or 17 wherein the semitransparent functional layer is based on a plasmonic color filter and in particular based on two-dimensional periodic nanostructures. Plasmonic color filters based on two-dimensional periodic nanostructures are known, for example, from DE 10 2011 101 635 A1. Foil after one of the Claims 16 to 23 In the case of diffuse reflection, in particular when viewed in daylight, the predetermined regions appear golden to the viewer and appear bluish in retroreflection, especially when viewed at night in the spotlight. Foil after one of the Claims 16 to 24 wherein the film has the following structure: - adhesive layer; Optionally, an opaque layer with recesses in the form of patterns, characters or an encoding; - semitransparent functional layer; - Carrier film. With a retroreflective structure provided data carrier, in particular a license plate or a license plate, a traffic sign or a traffic sign, a billboard or advertising space, or security clothing, comprising the film according to one of Claims 16 to 25 , Use of the film after one of Claims 16 to 25 for securing a data carrier provided with a retroreflective structure, in particular a license plate, a road sign, a billboard or advertising space, or safety clothing.

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