Retroreflective articles including a security mark

Patent metadata

Field	Value
Publication number	US-9964674-B2
Application number	US-201214344794-A
Country	US
Kind code	B2
Filing date	Sep 21, 2012
Priority date	Sep 23, 2011
Publication date	May 8, 2018
Grant date	May 8, 2018

Abstract

The present disclosure relates to prismatic retroreflective articles that includes a security mark and to methods of making such articles.

First claim

What is claimed is:

1. A retroreflective article, comprising:
a retroreflective layer comprising multiple cube corner elements that collectively form a structured surface;
one or more barrier layers positioned adjacent to the structured surface to form a low refractive index area between the one or more barrier layers and the cube corner elements having a refractive index of less than 1.3;
an opaque conforming layer positioned adjacent to the one or more barrier layers; and
one or more security mark layers positioned between the conforming layer and the cube corner elements;
wherein the barrier layers, conforming layer, and security mark layers each have a characteristic, wherein the characteristic is not the same for the barrier layers and the security mark layers, and wherein the characteristic is at least one of color or infra-red absorbency.

2. The retroreflective article of claim 1 , wherein the one or more security mark layers are positioned between the barrier layer and the structured surface.

3. The retroreflective article of claim 1 , wherein the one or more security mark layers are positioned directly between the conforming layer and the cube corner elements.

4. The retroreflective article of claim 1 , wherein at least one of the one or more security mark layers has a first portion positioned between the barrier layer and the cube corner elements and a second portion positioned between the cube corner elements and the conforming layer.

5. The retroreflective article of claim 1 , wherein at least some of the one or more barrier layers and at least some of the one or more security mark layers overlap.

6. The retroreflective article of claim 1 , wherein the one or more barrier layers and one or more security mark layers do not overlap.

7. The retroreflective article of claim 1 , wherein the one or more security mark layers are applied to at least a portion of the conforming layer.

8. The retroreflective article of claim 1 , wherein the one or more security mark layers are applied to at least a portion of the structured surface.

9. The retroreflective article of claim 1 , wherein the one or more security mark layers cover less than 100% of the structured surface.

10. The retroreflective article of claim 1 , wherein a portion of the structured surface adjacent to the one or more security mark layers is not retroreflective and a portion of the structured surface adjacent to the one or more barrier layers is retroreflective.

11. The retroreflective article of claim 1 , wherein the conforming layer is an adhesive.

12. The retroreflective article of claim 1 , wherein at least a portion of the one or more security mark layers can be distinguished from a background by a viewer in both ambient light and in retroreflection.

13. The retroreflective article of claim 1 , wherein at least a portion of the one or more security mark layers can be distinguished from a background by a viewer in ambient, but not in retroreflection.

14. The retroreflective article of claim 1 , wherein the one or more security mark layers have a characteristic that varies from a characteristic in one of (1) the one or more barrier layers or (2) the conforming layer.

15. The retroreflective article of claim 1 , wherein the conforming layer is white.

16. A method of forming a retroreflective article, comprising:
providing a retroreflective layer comprising multiple cube corner elements that collectively form a structured surface;
positioning one or more barrier layers adjacent to the structured surface to form a low refractive index area between the one or more barrier layers and the cube corner elements having a refractive index of less than 1.3;
positioning an opaque conforming layer adjacent to the one or more barrier layers;
positioning a security mark layer between the structured surface and the conforming layer, wherein the barrier layers, conforming layer, and security mark layers each have a characteristic, wherein the characteristic is not the same for the barrier layers and the security mark layers, and wherein the characteristic is at least one of color or infra-red absorbency; and
laminating the layers.

17. The method of claim 16 , wherein the conforming layer is white.

18. The method of claim 16 , wherein the one or more security mark layers are positioned between the barrier layer and the structured surface.

19. The method of claim 16 , wherein the one or more security mark layers are positioned directly between the conforming layer and the cube corner elements.

20. The method of claim 16 , wherein at least one of the one or more security mark layers has a first portion positioned between the barrier layer and the cube corner elements and a second portion positioned between the cube corner elements and the conforming layer.

21. The method of claim 16 , further comprising:
forming a pattern of the one or more barrier layers and/or the one or more security mark layers before the laminating step.

22. The method of claim 16 , further comprising:
patterning the one or more barrier layers and/or the one or more security mark layers onto the conforming layer before the laminating step to form a security mark void.

23. The method of claim 16 , wherein at least some of the one or more security mark layers and/or at least some of the one or more barrier layers is formed by curing a polymer-containing layer before the laminating step.

24. The method of claim 16 , wherein at least some of the one or more security mark layers and/or at least some of one or more barrier layers is printed onto the conforming layer.

25. The method of claim 16 , wherein at least a portion of the one or more security mark layers can be distinguished from the background by a viewer in both ambient light and in retroreflection.

26. The method of claim 16 , wherein at least a portion of the one or more security mark layers can be distinguished from the background by a viewer in ambient light, but not in retroreflection.

27. The method of claim 16 , wherein the conforming layer is an adhesive.

28. The method of claim 16 , wherein the security mark exhibits variable retroreflectivity.

29. The method of claim 16 , wherein the one or more security mark layers have a characteristic that varies from a characteristic in one of (1) the one or more barrier layers or (2) the conforming layer.

30. A retroreflective article, comprising:
a retroreflective layer comprising multiple cube corner elements that collectively form a structured surface;
one or more barrier layers positioned adjacent to the structured surface to form a low refractive index area between the one or more barrier layers and the cube corner elements having a refractive index of less than 1.3;
a conforming layer positioned adjacent to the one or more barrier layers; and
one or more security mark layers positioned between the conforming layer and the cube corner elements;
wherein the barrier layers, conforming layer, and security mark layers each have a characteristic, wherein the characteristic is not the same for the barrier layers and the security mark layers, and wherein the characteristic is at least one of color or infra-red absorbency.

Assignees

• 3M Innovative Properties Co

Inventors

• Patel Suman K
• Orensteen Bruce D
• Pekurovsky Mikhail L

Classifications

• G02B5/124 Primary

  plural reflecting elements forming part of a unitary plate or sheet · CPC title

• B42D25/382

  absorbing or reflecting infrared light · CPC title

• B42D25/47

  using adhesives · CPC title

• B42D25/324

  Reliefs · CPC title

• G07D7/003

  using security elements (using digital security elements G07D7/004) · CPC title