Retroreflective articles including optically active areas and optically inactive areas

• US 9,910,194 B2
• Filed: 04/15/2010
• Issued: 03/06/2018
• Est. Priority Date: 04/15/2010
• Status: Active Grant

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Free, Michael Benton, Thakkar, Bimal V., Mazurek, Mieczyslaw H., Smith, Kenneth L., Patel, Suman K., Coggio, William D., Pekurovsky, Mikhail L.
• Primary Examiner(s): Simone, Catherine A
• Application Number:
  US13/641,388
• Publication Number:
  US 20130034682A1
• Time in Patent Office: 2,882 Days
• Field of Search: 428156, 428166, 428 401, 428 418, 428343, 428161, 359529, 359530
• CPC Class Codes: G02B 5/124 plural reflecting elements forming part of a unitary plate or sheet
• CPC Class Codes: Y10T 156/10 Methods of surface bonding and/or assembly therefor
• CPC Class Codes: Y10T 428/23 Sheet including cover or casing
• CPC Class Codes: Y10T 428/24496 Foamed or cellular component
• CPC Class Codes: Y10T 428/24612 Composite web or sheet
• CPC Class Codes: Y10T 428/31504 Composite [nonstructural laminate]

Abstract

This disclosure generally relates to retroreflective articles and methods of making such articles.

Claims

1. A retroretlective article, comprising:

a retroreflective layer including multiple cube corner elements that collectively form a structured surface that is opposite a major surface;

a non-transparent pressure sensitive adhesive layer having a first region and a second region wherein the second region is in contact with cube corner elements of the structured surface;

a barrier layer disposed between the structured surface and the first region having sufficient structural integrity to substantially prevent flow of the non-transparent pressure sensitive adhesive into the structured surface corresponding to the first region; and

the first and second regions having sufficiently different properties to form a low refractive index layer between the non-transparent pressure sensitive adhesive layer and the structured surface of the retroreflective layer, wherein the first region is optically active and the second region is optically inactive.

2. The retroreflective article of claim 1, wherein the low refractive index layer includes at least one of air or a low refractive index material.

3. The retroreflective article of claim 1, wherein the non-transparent pressure sensitive adhesive layer is in intimate contact with the structured surface and is white in color.

4. The retroreflective article of claim 1, wherein the second region includes a pressure sensitive adhesive and the first region differs in composition from the second region.

5. The retroreflective article of claim 4, wherein the first region includes at least one of a resin, an ink, a dye, a pigment, a particle, a bead, an inorganic material, and a polymer.

6. The retroreflective article of claim 4, wherein the first region and the second region have different polymer morphology.

7. The retroreflective article of claim 4, wherein the first region and the second region have different flow properties.

8. The retroreflective article of claim 4, wherein the first region and the second region have different viscoelastic properties.

9. The retroreflective article of claim 4, wherein the first region and the second region have different adhesive properties.

10. The retroreflective article of claim 1, wherein the retroreflective layer includes a land portion on which the cube corner elements are formed.

11. The retroreflective article of claim 1, fiirther comprising a plurality of second regions that form a pattern.

12. The retroreflective article of claim 11, wherein the pattern is one of an irregular pattern, a random pattern, a regular pattern, a grid, words, graphics, images, lines, and intersecting zones that form cells.

13. The retroreflective article of claim 12, wherein the cell has a cell size that is less than 1000 μ

m.

14. The retroreflective article of claim 1, wherein the structured surface exhibits a total light return that is not less than about 5% for incident visible light at an entrance angle of −

4 degrees.

15. The retroreflective article of claim 1, wherein the structured surface exhibits a coefficient of retroreflection RA that is not less than about 40 cd/(lux·

m2) for an observation angle of 0.2 degrees and an entrance angle of −

4 degrees.

16. A retroreflective article, comprising:

a retroreflective layer including a structured surface that is opposite a major surface;

a white pressure sensitive adhesive that contacts at least a portion of the structured surface to form an optically inactive area that does not substantially retroreflect incident light;

at least one low refractive index layer forming an optically active area that retroreflects incident light; and

at least one barrier layer disposed between the white pressure sensitive adhesive and the low refractive index layer having sufficient structural integrity to substantially prevent flow of the white pressure sensitive adhesive into the low refractive index layer.

17. The retroreflective article of claim 16, wherein the low refractive index layer includes at least one of air or a low index material.

18. The retroreflective article of claim 16, wherein the optically inactive area defines a second region and the optically active area defines a first region and wherein the white pressure sensitive adhesive layer is in intimate contact with the structured surface.

19. The retroreflective article of claim 18, wherein the second region includes a pressure sensitive adhesive and the first region differs in composition from the second region.

20. The retroreflective article of claim 19, wherein the first region includes at least one of a resin, an ink, a dye, a pigment, a particle, a bead, an inorganic material, and a polymer.

21. The retroreflective article of claim 18, wherein the first region and the second region have different polymer morphology.

22. The retroreflective article of claim 18, wherein the first region and the second region have different flow properties.

23. The retroreflective article of claim 18, wherein the first region and the second region have different viscoelastic properties.

24. The retroreflective article of claim 18, wherein the first region and the second region have different adhesive properties.

25. The retroreflective article of claim 16, wherein the retroreflective layer includes a land portion on which the cube corner elements are formed.

26. The retroreflective article of claim 18, further comprising a plurality of second regions that form a pattern.

27. The retroreflective article of claim 26, wherein the pattern is one of an irregular pattern, a random pattern, a regular pattern, a grid, words, graphics, images, lines, and intersecting zones that form cells.

28. The retroreflective article of claim 16, wherein at least about 30% of the structured surface is retroreflective.

29. The retroreflective article of claim 16, including multiple optically active areas and multiple optically inactive areas and at least some of the optically inactive areas and optically active areas form a pattern.

30. The retroreflective article of claim 16, wherein the structured surface exhibits a total light return that is not less than about 5% for incident visible light at an entrance angle of −

4 degrees.

31. The retroreflective article of claim 16, wherein the structured surface exhibits a coefficient of retroreflection RA that is not less than about 40 cd/(lux·

m2) for an observation angle of 0.2 degrees and an entrance angle of −

4 degrees.

32. A method of forming a retroreflective article, comprising:

providing a retroreflective layer including multiple cube corner elements that collectively form a structured surface that is opposite a major surface;

applying a non-transparent pressure sensitive adhesive layer to the structured surface to form a first region and a second region, wherein the second region is in contact with the cube corner elements of the structured surface and the first region is not in contact with the structured surface; and

a barrier layer disposed between the structured surface and the first region having sufficient structural integrity to substantially prevent flow of the non-transparent pressure sensitive adhesive to prevent contact of the non-transparent pressure sensitive adhesive with the structured surface corresponding to the first region.

33. The method of claim 32, wherein multiple second regions are in contact with the first region and thereby create a discrete first region.

34. The method of claim 32, wherein the non-transparent pressure sensitive adhesive layer is structured.

35. The method of claim 32, further comprising:

laminating a structured adhesive to the structured surface.

36. The method of claim 32, where in the non-transparent pressure sensitive adhesive is one of a structured pressure sensitive white colored adhesive and an unstructured pressure sensitive white colored adhesive.

37. The method of claim 32, wherein the non-transparent pressure sensitive adhesive is a structured pressure sensitive adhesive including a raised region and the raised region corresponds to the second region.

38. The method of claim 32, wherein a second major surface of the non-transparent pressure sensitive adhesive layer is adjacent to a liner.

39. The method of claim 32, further comprising:

laminating the non-transparent pressure sensitive adhesive layer to the structured surface of the retroreflective layer.

40. The method of claim 32, wherein the non-transparent pressure sensitive adhesive layer has a second major surface opposite the first and second regions, wherein the second major surface of the non-transparent pressure sensitive adhesive layer is adjacent to a liner.