Security element with metallization

1. A security element for security papers or value documents, comprising a substrate and an opaque metallization arranged on the substrate, characterized in that the metallization comprises a first opaque metal layer having an optical density of at least 0.5 and a different second opaque metal layer arranged above the first metal layer and having an optical density of at least 0.5, wherein the two metal layers have substantially the same tone of color in the visible spectral region and differ significantly in their chemical and/or mechanical durability;

wherein the optical density of each of the two metal layers is larger than 1.2; and

wherein the second metal layer is a corrosion-resistant metal layer of platinum, palladium, or chrome.

2. The security element according to claim 1 , characterized in that the second metal layer is chemically and/or mechanically more durable than the first metal layer.

3. The security element according to claim 1 , characterized in that the metal layers differ in their reflectivity and the first metal layer reflects more strongly than the second metal layer.

4. The security element according to claim 1 , characterized in that the optical density of the two metal layers is substantially the same.

5. The security element according to claim 1 , characterized in that the optical density of the two metal layers together is between 1.5 and 5.0, preferably between 1.5 and 3.0.

6. The security element according to claim 1 , characterized in that the second metal layer is a chrome layer having a thickness of about 25 nm or more.

7. The security element according to claim 1 , characterized in that the first metal layer is an aluminum layer.

8. The security element according to claim 7 , characterized in that the aluminum layer has a thickness of about 15 nm or more.

9. The security element according to claim 1 , characterized in that a spacing layer is provided between the metal layers.

10. The security element according claim 9 , characterized in that the spacing layer forms an electrical and/or chemical isolation layer.

11. The security element according claim 9 , characterized in that the spacing layer is formed by a transparent printing layer or a transparent vapor deposited layer.

12. The security element according to claim 9 , characterized in that the spacing layer is formed by a ceramic layer, in particular a SiO x -layer, an Al 2 O 3 -layer or a MgF 2 -layer, or by an organic layer.

13. The security element according to claim 9 , characterized in that the spacing layer forms a barrier layer against the permeation of gases and vapors, in particular of oxygen and hydrogen.

14. The security element according to claim 1 , characterized in that the security element comprises a diffraction structure in form of a relief structure.

15. The security element according to claim 14 , characterized in that the diffraction structure encompasses an embossed embossing lacquer layer and at least a partial area of the metal layers.

16. The security element according to claim 1 , characterized in that the metal layers comprise gaps reaching through both metal layers and being in the form of patterns, characters or a code.

17. The security element according to claim 1 , characterized in that the first metal layer is not contiguous.

18. The security element according to claim 1 , characterized in that the security element represents a security thread, a security band or a patch.

19. A security paper for the manufacturing of value documents, which is provided with the security element according to claim 1 .

20. A data carrier, in particular a value document, such as a bank note or an identity card, which is provided with the security element according to claim 1 .

21. A use of the security element according to claim 1 , of a security paper provided with the security element, or of a data carrier provided with the security element for protection of goods against counterfeiting.

22. A method of producing a security element for security papers or value documents, comprising the steps wherein

a substrate is provided, a first opaque metal layer having an optical density of at least 0.5 is arranged on the substrate, and a second different opaque metal layer having an optical density of at least 0.5 is arranged above the first metal layer, which second metal layer has substantially the same tone of color in the visible spectral region as the first metal layer and differs significantly from the first metal layer in its chemical and/or mechanical durability;

wherein the optical density of each of the two metal layers is larger than 1.2; and

wherein the second metal layer is a corrosion-resistant metal layer of platinum, palladium, or chrome.

23. The method according to claim 22 , characterized in that the two metal layers are applied by means of a vacuum coating process.

24. The method according to claim 22 , characterized in that a chrome layer is applied as second metal layer.

25. The method according to claim 22 , characterized in that an aluminum layer is applied as first metal layer.

26. The method according to claim 22 , characterized in that a spacing layer is applied between the first and the second metal layer.

27. The method according claim 26 , characterized in that the spacing layer is printed or vapor deposited in a vacuum coating process.

28. The method according to claim 22 , characterized in that the security element is provided with a diffraction structure in form of a relief structure.

29. The method according claim 28 , characterized in that an embossing lacquer is applied onto the substrate, the embossing layer is embossed into the form of a desired diffraction structure and the first and second metal layer are applied onto the embossed lacquer layer.

30. The method according to claim 22 , characterized in that gaps reaching through both metal layers and being in the form of patterns, characters or a code are introduced into the metal layers.

31. The method according to claim 22 , characterized in that the first metal layer is not contiguous.

32. A security paper for the manufacturing of value documents, which is provided with the security element producible according to claim 22 .

33. A data carrier, in particular a value document, such as a bank note or an identity card, which is provided with the security element producible according to claim 22 .

34. A use of the security element producible according to claim 22 for protection of goods against counterfeiting.