EP2032355A1

EP2032355A1 - Substrate with a sequence of layers to produce a changing color impression depending on viewing angle

Info

Publication number: EP2032355A1
Application number: EP07785811A
Authority: EP
Inventors: Hans Kosak; Ralph Domnik
Original assignee: Identif GmbH
Current assignee: Secutech International Pte Ltd
Priority date: 2006-06-09
Filing date: 2007-06-08
Publication date: 2009-03-11
Also published as: WO2007141040A1; DE102006027263A1

Abstract

The invention relates to a substrate (1, 8, 9) with a sequence of layers (2, 7) thereon to produce a changing color impression depending on the viewing angle, with the sequence of layers (2, 7) having a reflecting layer (3) that reflects electromagnetic waves, a spacing layer (4) on the reflecting layer (3) that is transparent to electromagnetic waves, and an absorbing layer (5) of metallic clusters on the spacing layer (4), wherein the reflecting layer (3) is partially transparent to electromagnetic waves.

Description

Substrate with a layer sequence for producing a color impression which changes as a function of the viewing angle

The invention relates to a substrate having a layer sequence provided thereon for producing a color impression which changes as a function of the viewing angle, according to the preamble of patent claim 1.

Such a substrate is known from WO 02/18155. The known substrate forms a forgery-proof mark, which is attached to the respective objects to prove the authenticity of means of payment, brand name products or the like. On the basis of the observable with the known substrate dependency of the color impression from the viewpoint whose authenticity can be detected in particular automatically using a reader.

DE 10 2004 001 655 A1 describes a window glass which is provided with a heat protection coating. The thermal protection coating consists of a sequence of different dielectric layers and an interposed metal layer. She is color neutral.

DE 10 2004 054 348 A1 describes a method for producing a laminated glass. In this case, a carrier glass is pretreated with a bonding agent and then applied to the carrier glass at least one layer of resin surface. As the resin, a liquid, UV-resistant IK polyurethane material is used, which essentially comprises a prepolymer of an aliphatic isocyanate 3asis low monomeric units and wherein a temperature is provided for curing of the resin to about 3O ⁰ C. There is a particular need in the field of window glass industry to provide window glass, which are characterized by a special color impression.

The object of the invention is to satisfy this need. It should be specified in particular a substrate that is characterized by a special color impression and at the same time suitable for use as window glass.

This object is solved by the features of claim 1. Advantageous embodiments of the invention will become apparent from the features of claims 2 to 22nd

According to the invention, it is provided that the reflection layer for electromagnetic waves is partially permeable. It has surprisingly been found that the change in the color impression caused by the layer sequence "reflection layer / spacer layer absorber layer" as a function of the viewing angle can still be achieved even if the reflection layer is only partially permeable. The aforesaid sequence of layers can therefore be produced overall with such a transparency that it can be used in combination with a transparent to visible light substrate, for. B. window glass, is usable. A window glass coated with the proposed layer sequence is characterized by a unique color impression that changes depending on the viewing angle. Experiments have also shown that the proposed layer sequence is characterized by a particularly high UV and Lichtstabili- fact. Apart from that, it has been found that the color impression which changes depending on the viewing direction is particularly temperature-stable. It is possible to heat a coated with the proposed layer sequence substrate to temperatures of up to 650 ⁰ C, without that In the process, the color impression that changes depending on the angle of view changes significantly.

According to an advantageous embodiment, the reflection layer has a transmission of more than 20%, preferably more than 50%, particularly preferably more than 70%, for the wavelength range of visible light. It can be made of at least one of the following metals: Ag, Au, Al, Ti, Cr. It has proved to be expedient for the reflection layer to have a thickness of from 4 to 80 nm, preferably from 8 to 40 nm, particularly preferably from 10 to 20 nm.

According to a first variant, the layer sequence is connected to the substrate via the reflection layer. According to a second variant, however, the layer sequence can also be connected to the substrate via the absorber layer. In this case, therefore, the absorber layer is applied to the substrate. The absorber layer is superimposed by the spacer layer and the reflection view.

The reflection layer or the absorber layer can be connected to the substrate via an adhesion-promoting layer. ^" The adhesion-promoting layer can be produced, for example, from ZnO.

The spacer layer expediently has a transmission of more than 90% for the wavelength range of visible light. It may have a thickness of from 20 to 1000 nm, preferably from 100 to 900 nm, particularly preferably from 200 to 800 nm. The absorber layer is expediently formed from island-like clusters with a size of 5 to 100 nm. The absorber layer formed from the clusters is therefore not a continuous metallic layer but a layer in which the clusters are island-like with a predetermined average minimum distance from each other. The minimum distance is chosen so that surface plas- mons can form in the absorber layer. 5

The clusters can be made of at least one of the following metals: Au, Al, Ti, Zr, Ag, Cr, Cu. The clusters can have an average thickness of 4 to 30 nm, preferably 5 to 20 nm, particularly preferably 8 to 16 nm.

In the plan view of the absorber layer, the clusters advantageously have an average lateral diameter of 5 to 200 nm, preferably 10 to 100 nm, particularly preferably 15 to 50 nm. The proposed absorber layer indicates the wavelength range of the visible

L5 advantageously has a transmission of more than 70%, preferably more than 80%, particularly preferably more than 90%. In combination with the reflection layer according to the invention, it is outstandingly suitable for producing a layer sequence with an overall high transmission

ZQ for the wavelength range of visible light of more than 50%, preferably more than 70%, more preferably more than 80%.

According to a further embodiment of the invention, a transparent protective layer is applied to the absorber layer. The protective layer also has a transmission of more than 50%, preferably more than 70%, particularly preferably more than 90%, for the wavelength range of visible light. The protective layer stabilizes the layer sequence and serves in particular against mechanical abrasion.

The spacer layer and / or the protective layer can be made of an oxide, nitride or oxynitride of at least one of the following elements: Si, Zn, Al, Ti. The spacer layer can alternatively also be made of a polymer, preferably be made of nitrocellulose. In this case, the spacer layer may be conveniently prepared by a printing process. According to a further alternative, the protective layer can also be produced from a further polymer. It can be a transparent lacquer.

According to a particularly advantageous embodiment, the reflective layer and / or the spacer layer and / or the absorber layer and / or the protective layer is produced by means of a vacuum encapsulation method, in particular sputtering. The aforementioned layers can be applied successively in successive steps in a single vacuum deposition equipment.

The substrate according to the invention may in particular be a transparent plastic film, a transparent plastic pane, window glass, preferably a window glass with a heat protection coating, or a window glass pane of a laminated glass. The substrate expediently has a transmission of more than 70%, preferably more than 80%, particularly preferably more than 90%, in the visible light range.

According to a further embodiment of the invention, the layer sequence according to the invention can be combined with conventional layer sequences provided on window glasses, in particular IR sequences reflecting layer sequences. For this purpose, the reflection view according to the invention can replace a metal layer in IR-reflecting layer sequences. The dielectric layers provided in IR layer sequences may be replaced by the spacer layer. However, it is also possible for the spacer layer to be replaced by a conventional dielectric layer used in IR layer sequences. Embodiments of the invention will be explained in more detail with reference to the drawings. Show it:

1 shows schematically a first substrate with a first layer sequence,

Fig. 2 shows schematically the first substrate with a second

Layer sequence,

3 shows schematically a second substrate with the layer sequence according to FIG. 1,

4 shows the first substrate with the layer sequence according to FIG. 3, FIG.

Fig. 5 shows a third substrate with a third layer sequence and

6 shows the first substrate with the layer sequence according to FIG. 5.

In FIG. 1, a first layer sequence, generally designated by the reference numeral 2, is applied to a first substrate 1 produced, for example, from window glass, in particular float glass.

In FIG. 1, the first layer sequence 2 is formed from a semitransparent reflection layer 3 applied to the first substrate 1, which z. B. made of aluminum or gold with a thickness of 20 nm. The reflection layer 3 is superposed by a dielectric spacer layer 4 having a thickness of 400 nm. The spacer layer 4 is z. B. made of Al ₂ O ₃ , ZnO or SiO ₂ . The spacer layer 4 in turn is overlaid by an absorber layer 5. gert, which consists of island-like arranged Ag clusters with an average thickness of 10 ran. In the plan view of the absorber layer 5, the Ag clusters have a mean lateral diameter of approximately 30 nm. The absorber layer 5 in turn is superimposed by a protective layer 6, which may be made of SiO ₂ or a transparent lacquer, for example.

In FIG. 2, the first substrate 1 is coated with a second layer sequence 7. In this case, the absorber layer 5 is applied to the first substrate 1. The absorber layer 5 is superimposed by the spacer layer 4. The spacer layer 4 is superimposed by the semitransparent reflection layer 3. The reflection layer 3 in turn is superimposed by the protective layer 6.

If a float glass is used as the first substrate 1, the first 2 and the second layer sequence 7 are expediently applied on that side of the glass which was in contact with the tin bath during the production process.

Experiments have shown that the layer sequences 2, 7 better adhere to this side. Alternatively, the layer sequences 2, 7 can also be applied to an applied on the substrate 1 adhesive layer, which z. B. made of ZnO, are applied.

Fig. 3 shows a second substrate 8, which is made of a transparent plastic film. The second substrate 8 is connected to the first layer sequence 2. The second substrate 8 may be provided on its side facing away from the reflection layer 3 with an adhesive layer. With the embodiment shown in Fig. 3, for example, transparent packaging means or the like can be produced. In addition, it is also possible, the second substrate 8 aufzulami on a solid, preferably transparent, substrate kidney. FIG. 4 shows the first substrate 1 in combination with the second substrate 8 shown in FIG. 3. The second substrate 0 is glued to the first substrate 1. The embodiments shown in FIGS. 3 and 4 are suitable, for example, for subsequently providing a window glass pane with the layer sequence according to the invention. For this purpose, the second substrate 8 designed as a flexible plastic film can be bonded to a conventional window glass pane.

FIG. 5 shows a third substrate 9, which superimposes and underlies the first layer sequence 2. The third substrate 9 may be another plastic film commonly used to make laminated glass. The third substrate 9 may be adhered to two panes of glass using a suitable adhesive to produce a laminated glass pane.

6 schematically shows a laminated glass pane in which the layer sequence shown in FIG. 5 is overlaid and underlaid by a window glass pane 1.

LIST OF REFERENCE NUMBERS

1 first substrate

2 first layer sequence 3 reflection layer

4 spacer layer

5 absorber layer

6 protective layer

7 second layer sequence 8 second substrate

9 third substrate

Claims

claims

1. substrate (1, 8, 9) having a layer sequence (2, 7) provided thereon for producing a color impression which changes as a function of the viewing angle, wherein the layer sequence (2, 7) comprises an electromagnetic wave reflecting reflection layer (3), a spacer layer (4) which is permeable to electromagnetic waves and bears on the reflective layer (3) and has an absorber layer (5) formed on the spacer layer (4) and formed from metallic clusters,

characterized in that

the electromagnetic wave reflection layer (3) is partially transmissive, and that the substrate (1) is a transparent window pane or a plastic film (8, 9) applied to a transparent window pane.

2. Substrate according to claim 1, wherein the reflection layer (3) for the wavelength range of visible light has a transmission of more than 20%, preferably more than 50%, particularly preferably more than 70%.

3. Substrate according to one of the preceding claims, wherein the reflection layer (3) has a thickness of 4 to 80 nm, preferably 8 to 40 nm, particularly preferably from 10 to 20 nm.

4. Substrate according to one of the preceding claims, wherein the layer sequence (2, 7) via the absorber layer (5) to the substrate (1, 8, 9) is connected.

5. Substrate according to one of the preceding claims, wherein the reflection layer (3) or the absorber layer (5) via an adhesion-promoting layer to the substrate (1, 8, 9) is connected.

6. Substrate according to one of the preceding claims, wherein the adhesion-promoting layer is made of ZnO.

A substrate according to any one of the preceding claims, wherein the wavelength lapse region of the visible light spacer layer (4) has a transmission of more than 90%.

8. Substrate according to one of the preceding claims, wherein the absorber layer (5) of island-like clusters having an average lateral diameter of 5 to 200 nm, preferably 10 to 100 nm, more preferably 15 to 50 nm, is formed.

A substrate according to any one of the preceding claims, wherein the clusters are made of at least one of the following metals: Au, Al, Ti, Zr, Ag, Cr, Cu.

10. Substrate according to one of the preceding claims, wherein the absorber layer (5) of island-like clusters having an average thickness of 4 to 30 nm, preferably 5 to 20 nm, more preferably from 8 to 16 nm, is formed.

11. Substrate according to one of the preceding claims, wherein the absorber layer (5) for the wavelength range of the visible light has a transmission of more than 70%, preferably more than 80%, particularly preferably more than 90%.

12. Substrate according to one of the preceding claims, wherein a transparent protective layer (6) is applied to the absorber layer (5).

13. Substrate according to one of the preceding claims, wherein the spacer layer (4) and / or the protective layer (6) made of an oxide, nitrite or Oxinitrit at least one of the following elements: Si, Zn, Al, Ti.

14. A substrate according to any one of claims 1 to 12, wherein the spacer layer (4) is made of a polymer, preferably nitrocellulose.

15. A substrate according to claim 14, wherein the spacer layer (4) is made by a printing process.

16. Substrate according to one of the preceding claims, wherein the protective layer (6) is made of a further polymer.

17. Substrate according to one of the preceding claims, wherein the reflective layer (3) and / or the spacer layer (4) and / or the absorber layer (5) and / or the protective layer (6) by means of a vacuum evaporation method, in particular sputtering, is prepared.

18. Substrate according to one of the preceding claims, wherein the substrate is a window glass with a heat protective coating or a window glass pane of a laminated glass.

19. Use of a layer sequence (2, 7) for producing a color impression which changes as a function of the viewing angle, wherein the layer sequence (2, 7) comprises an electromagnetic wave-reflecting reflection layer (3), an electromagnetic wave-transmissive spacer layer superimposed on the reflection layer (3) (4) and having an absorber layer (5) formed of metallic clusters on the spacer layer (4), wherein the electromagnetic wave reflection layer (3) is partially transmissive, as a coating for a transparent window pane.

20. Use of a plastic film (8, 9) as a substrate for a layer sequence (2, 7) provided thereon for producing a color impression which changes as a function of the viewing angle, wherein the layer sequence (2, 7) comprises an electromagnetic wave-reflecting reflection layer (3) on the reflection layer (3) superimposed for electromagnetic wave-transmitting spacer layer (4) and on the spacer layer (4) supporting, formed of metallic clusters absorber layer (5), wherein the reflective layer (3) is partially transparent to electromagnetic waves, as a coating for a transparent windowpane.