SECURITY ELEMENT WITH COLOR SHIFT EFFECT AND MANIPULATION DETECTION

Abstract

The invention relates to a security element with manipulation detection, in particular a security label or a transferable element, having the following layers: a) a first layer which is an embossed support substrate or a support substrate (1) with a coating layer (6) that has an optically active structure (7) or a first liquid crystal layer, b) a second layer which is a liquid crystal layer (3), c) a light-absorbing layer (4), and d) an adhesive layer (5), wherein the adhesion between the layers a. and b. is lower than the adhesion between the layers b., c., and d., and the security element has a color shift effect.

Claims

1-12. (canceled)

13. A tamper-evident security element, more particularly a security label and/or a transferable element, characterized in that it comprises the following layers: a. a first layer representing a full-arealy or partially embossed supporting substrate 8 or a supporting substrate 1 comprising a full-areal or partial lacquer layer 6 comprising an optically active structure 7 or a full-areal or partial first liquid-crystalline layer 2, b. a second layer representing a liquid-crystalline layer 3, c. optionally a light-absorbing layer 4, d. an adhesive coating 5, wherein the adherence between the layers a. and b. is lower than the adherence between the layers b. c. and d. and wherein the security element comprises a color tilt effect.

14. The security element as claimed in claim 13, wherein the first layer represents a supporting substrate 1 comprising a lacquer layer 6 comprising an optically active structure 7 or a first liquid-crystalline layer 2, an adhesion promoter is provided between the supporting substrate 1 and the lacquer layer 6 or liquid-crystalline layer 2.

15. The security element as claimed in claim 13, wherein the adherence between the layers a. and b. is established by surface modification of the physical or chemical type.

16. The security element as claimed claim 13, wherein the optically active structure 7 is a diffraction-optically active structure, such as a hologram, a surface relief, a diffraction structure, a diffraction grating, a kinegram or an embossment 1-100 μm in depth.

17. The security element as claimed in claim 13, wherein the layer a. represents a first liquid-crystalline layer 2 applied atop a supporting substrate 1 the second liquid-crystalline layer 3 comprises a different hue and/or color tilt effect than the first liquid-crystalline layer 2.

18. The security element as claimed in claim 13, wherein the first lacquer layer 6 is a radiatively curable type of lacquer layer.

19. The security element as claimed in claim 13, wherein the first lacquer layer 6 is a thermoplastic type of lacquer layer.

20. The security element as claimed in claim 13, wherein the lacquer layer 6 or the first liquid-crystalline layer 2 or the liquid-crystalline layer 3 are engineered as partial layers.

21. The security element as claimed in claim 13, wherein the light-absorbing layer 4 is applied partially or full-arealy.

22. The security element as claimed in claim 13, wherein the light-absorbing layer 4 is formed by a light-absorbing printed layer or by a light-absorbing metallic coating.

23. The security element as claimed in claim 13, wherein the adhesive coating 5 is a self-adhesive coating, a cold-sealable coating or a heat-sealable coating.

24. The method of using the security element as claimed in claim 13 for security labels, adhesive tapes or security foils.

Description

[0057] FIGS. 1 to 7 depict exemplary embodiments of the security element according to the present invention.

[0058] In the figures,

[0059] 1 denotes a supporting substrate

[0060] 2 denotes a layer of a first liquid-crystalline material,

[0061] 3 denotes a layer of a (second) liquid-crystalline material,

[0062] 4 denotes a light-absorbing layer,

[0063] 5 denotes an adhesive coating,

[0064] 6 denotes a lacquer layer,

[0065] 7 denotes an optically active structure,

[0066] 8 denotes an embossed supporting substrate,

[0067] 9 denotes a primer layer.

[0068] FIG. 1 shows a security element comprising a supporting substrate 1 provided a first layer of liquid-crystalline material 2. Atop this first layer of a first liquid-crystalline material 2 is a second layer of a second different liquid-crystalline material 3.

[0069] The light-absorbing layer 4 in this example consists of a black printed layer. A self-adhesive coating 5 may be used to fix the security element on the object to be secured. A superimposed color tilt effect of the two layers 2 and 3 is discernible on inspection.

[0070] A tampering attempt will cause the first liquid-crystalline layer 2 to separate from the second liquid-crystalline layer 3, since the adherence between these two layers has been engineered to be weaker than the adherence between the remaining layers.

[0071] A tampering attempt will reveal, in the background to be secured, the hue and/or the color tilt effect of the second liquid-crystalline layer 3, this hue and/or color tilt effect differing from that of the intact security element.

[0072] In FIG. 2, a lacquer layer 6 comprising an optically active structure 7 is provided in place of the first liquid-crystalline layer. The light-absorbing layer 4 is formed of a coating of astoichiometric alumina. This light-absorbing layer 4 is subsequently provided a primer layer 9. To fix the security element on the article to be secured, a heat-sealing lacquer coating is provided as adhesive coating 5.

[0073] The optically active effect is non-discernible in the intact state provided the refractive index of lacquer layer 6 has been conformed to the refractive index of layer 3 of liquid-crystalline material. However, the color tilt effect due to layer 3 is discernible. A tampering attempt will cause the optically active structure to separate from the layer of liquid-crystalline material 3, revealing the optically active structure not only as a positive in the first (removed) layer but also as a negative in the second layer (remaining behind on the object to be secured) of liquid-crystalline material.

[0074] In FIG. 3, a layer of a liquid-crystalline material 3 has been applied atop an embossed supporting substrate, for example a hot-embossed sheet 8. A partial metallic coating of astoichiometric copper oxide has been applied as light-absorbing layer 4.

[0075] The security element is fixed via a self-adhesive coating 5 to the object to be secured. A tampering attempt will cause the layer of liquid-crystalline material 3 to separate from the hot-embossed sheet 8.

[0076] The optically active effect is non-discernible in the intact state provided the refractive index of hot-embossed sheet 8 has been conformed to the refractive index of layer 3 of liquid-crystalline material. However, the color tilt effect due to layer 3 is discernible. A tampering attempt will cause the optically active structure to separate from the layer of liquid-crystalline material 3, revealing the optically active structure of the hot-embossed sheet not only as a positive in the first (removed) layer but also as a negative in the second layer (remaining behind on the object to be secured) of liquid-crystalline material.

[0077] FIG. 4 depicts an embodiment constructed without a light-absorbing layer. In this case, the intensity of the visible color tilt effect is determined by the degree to which the article to be secured absorbs light.

[0078] The lower the light absorption of the background, the weaker the color tilt effect. In the event of a tampering attempt, a security element as per this embodiment behaves similarly to the security element depicted in FIG. 2.

[0079] The security element of FIG. 5 is constructed in a similar way to the security element depicted in FIG. 2, except for having a partial layer 3 of liquid-crystalline material.

[0080] The color tilt effect is partially discernible in the intact state. In the event of a tampering attempt, a security element as per this embodiment will behave essentially similarly to the security element depicted in FIG. 2. The layer of liquid-crystalline material will separate from the lacquer layer 6 comprising an optically active structure 7. The light-absorbing layer will remain behind on the layer 6 in those areas where there is no layer 3.

[0081] In the embodiment of FIG. 6, the lacquer layer 6 is provided a partial optically active structure.

[0082] This partial optically active effect is non-discernible in the intact state provided the refractive indices of lacquer layer 6 and of layer 3 have been conformed to each other. When the two refractive indices have not been conformed to each other, the optically active effect is discernible even in the intact state.

[0083] In the event of a tampering attempt the security element as per this embodiment will behave similarly to the security element depicted in FIG. 2. In a further embodiment, lacquer layer 6 may be provided in partial form as well as the optically active structure 7.

[0084] In the embodiment depicted in FIG. 7, both the layer of liquid-crystalline material 3 and the light-absorbing layer 4 are in partial form.

[0085] In this case, the color tilt effect is partially discernible not only in the intact state but also after a tampering attempt.