Multilayer body and method for producing a security element

Patent metadata

Field	Value
Publication number	US-10926570-B2
Application number	US-201815875446-A
Country	US
Kind code	B2
Filing date	Jan 19, 2018
Priority date	Nov 6, 2012
Publication date	Feb 23, 2021
Grant date	Feb 23, 2021

Abstract

A multilayer body ( 1, 2, 3 ) and a method for producing a security element are described. The multilayer body has a metal layer ( 21 ). An optically active surface relief is molded at least in areas in a first surface of the metal layer ( 21 ) facing the upper side of the multilayer body or forming the upper side of the multilayer body and/or in a second surface of the metal layer ( 21 ) facing the underside of the multilayer body or forming the underside of the multilayer body. In at least one first area ( 31 to 39 ) of the multilayer body the surface relief is formed by a first relief structure ( 61 ). In at least one direction ( 617 ) determined by an allocated azimuth angle, the first relief structure ( 61 ) has a sequence of elevations ( 612 ) and depressions ( 614 ), the elevations ( 612 ) of which follow on from each other with a period P which is smaller than a wavelength of visible light, wherein the minima of the depressions ( 614 ) lie on a base surface and the first relief structure ( 61 ) has a relief depth t which is determined by the spacing of the maxima of the elevations ( 612 ) of the first relief structure ( 61 ) from the base surface in a direction perpendicular to the base surface. The profile shape and/or the relief depth t of the first relief structure ( 61 ) is chosen such that the colored appearance of the light ( 52, 53 ) incident on the first area ( 31 to 39 ) at least at a first angle of incidence and directly reflected by the metal layer ( 21 ) in the first area or directly transmitted through the metal layer is modified, in particular is modified by plasmon resonance of the metal layer with the incident light.

First claim

The invention claimed is:

1. A security element for security documents, the security element comprising a multilayer body with an upper side and an underside, wherein the multilayer body has a metal layer with a first surface facing in a direction toward the upper side of the multilayer body and a second surface facing in a direction toward the underside of the multilayer body; and
wherein the multilayer body further comprises a first layer bordering at least one of the first and second surfaces of the metal layer and a second layer bordering the other of the first and second surfaces of the metal layer,
wherein an optically active surface relief is molded in areas of at least one of the first and second surfaces of the metal layer, and wherein, in at least one first area of the multilayer body, the surface relief is formed by a first relief structure which has a sequence of elevations and depressions, the elevations of which follow on from each other with a period P which is smaller than a wavelength of visible light, wherein the minima of the depressions lie on a base surface and the first relief structure has a relief depth t which is determined by the spacing of the maxima of the elevations of the first relief structure from the base surface in a direction perpendicular to the base surface, and
wherein the sequence of elevations and depressions define a profile shape, wherein the profile shape or the relief depth t of the first relief structure is chosen such that the colored appearance of the light incident on the first area at least at one first angle of incidence and reflected directly by the metal layer in the first area or transmitted directly through the metal layer is modified by plasmon resonance of the metal layer with the incident light, and
wherein at least one of the first layer and second layer has dyes or luminescent substances, wherein the first or second layer covers the first surface or the second surface of the metal layer in areas or over the whole surface in the first area or in at least one of the first areas in which the first relief structure is molded into the first or second surface of the metal layer, and
wherein, in the first area or in at least one of the first areas, the first or second layer having the dyes or luminescent substances is arranged less than 1 μm away from the first surface or the second surface of the metal layer, and
wherein the dyes or luminescent substances comprise a soluble dye or luminescent substance which is dissolved in the binder of the at least one of the first or second layer, and
wherein the at least one of the first or second layer having the dyes or luminescent substances has a transmittance of at least 70% in the wavelength range visible to the human eye, and
wherein the first layer or the second layer is applied to the first surface or second surface of the metal layer only in the first area, or the first layer or the second layer is applied to the first or second surface of the metal layer only in areas of the first surface or second surface in which the first relief structure is molded into the first surface or second surface, and wherein the percentage by weight of the dye or of the luminescent substance in the dry weight of the first or second layer is between 0.5% and 10%.

2. The security element according to claim 1 , wherein the profile shape and/or the relief depth t of the first relief structure is chosen such that at a second angle of incidence different from the first angle of incidence the colored appearance of the light reflected directly by the metal layer in the first partial area or transmitted directly through the metal layer is modified differently wherein different colors appear at these angles of incidence in the case of reflected light observation and in the case of transmitted light observation.

3. The security element according to claim 1 , wherein the first relief structure has a profile shape that is asymmetrical in relation to the base surface.

4. The security element according to claim 1 , wherein the elevations of the first relief structure have a width measured at a distance of t/2 from the base surface and the depressions of the first relief structure have a width measured at a distance of t/2 from the base surface, wherein the width of the elevations or the width of the depressions is greater than 0.6×P, or less than 0.4×P.

5. The security element according to claim 1 , wherein the edge steepness of the first relief structure, at a distance t/2 from the base surface, is between 70° and 85°.

6. The security element according to claim 1 , wherein the first relief structure has an edge steepness measured at a distance between t/4 and 3/4 t from the base surface, the edge steepness forming an angle of between 50° and 85°.

7. The security element according to claim 1 , wherein the first relief structure has an edge steepness measured at a distance between 0 and t/4 from the base surface or measured at a distance between 3/4t and t from the base surface, the edge steepness forming an angle of between 0° and 40° with respect to the base surface.

8. The security element according to claim 1 , wherein the period P of the first relief structure is between 250 nm and 450 nm.

9. The security element according to claim 1 , wherein the relief depth t of the first relief structure is between 100 nm and 400 nm.

10. The security element according to claim 1 , wherein, in the first area, the metal layer has a layer thickness of between 10 nm and 100 nm.

11. The security element according to claim 1 , wherein, in the first area, the metal layer has a layer thickness d which corresponds to an optical depth of between 0.7 and 2.3.

12. The security element according to claim 1 , wherein the first relief structure is a cross grating which has a sequence of elevations and depressions in two directions.

13. The security element according to claim 1 , wherein the surface relief in one or more second areas and/or further areas is formed by a second relief structure which is or are selected from the group: diffractive relief structure, holographic relief structure, mirror surface, mat structure, macrostructure, lens, grid of microlenses.

14. The security element according to claim 13 , wherein the at least one first area and the at least one second area are formed by a plurality of partial areas, wherein the partial areas of the first area and the partial areas of the second area are interleaved.

15. The security element according to claim 13 , wherein the at least one second area is formed by a plurality of partial areas separated from each other, and the first area surrounds these partial areas of the background area.

16. The security element according to claim 1 , wherein the first area or at least one of the first areas has a patterned shaping and has a shaping which contains an item of information which can only be made visible using an aid, and is molded in the form of a nanotext or a moire pattern.

17. The security element according to claim 1 , wherein the first area or at least one of the first areas comprises one or more first zones in which one or more of the parameters of the first relief structure selected from the group: period P, azimuth angle, relief depth t, base surface area and profile shape, differ from the corresponding parameters of the first relief structure in one or more second zones of the first area.

18. The security element according to claim 17 , wherein the one or more first and second zones are molded to form a motif, wherein the first zones form a foreground area of the

Assignees

• Ovd Kinegram Ag
• Ovd Kinegram

Inventors

• Walter Harald
• Tompkin Wayne Robert

Classifications

• G02B5/008 Primary

  Surface plasmon devices (diffractive gratings with a pitch less than or comparable to the wavelength G02B5/1809; surface plasmons in integrated optics G02B6/1226; optical analysis of materials by means of surface plasmons G01N21/553) · CPC title

• B41F19/02

  with embossing · CPC title

• B42D25/29 Primary

  Securities; Bank notes · CPC title

• B42D25/328

  Diffraction gratings; Holograms · CPC title

• B42D25/373

  Metallic materials · CPC title