Retroreflective articles including optically active areas and optically inactive areas

• US 10,379,271 B2
• Filed: 02/02/2018
• Issued: 08/13/2019
• 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:
  US15/887,479
• Publication Number:
  US 20180180779A1
• Time in Patent Office: 557 Days
• 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 retroreflective article, comprising microsealed prismatic sheeting, which comprises:

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

a pigment-containing 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 low refractive index layer between the first region of the adhesive layer and the structured surface of the retroreflective layer, and

a barrier layer disposed between the structured surface and the first region,

wherein the prismatic sheeting has a CAP Y greater than 50.

2. The retroreflective article of claim 1, wherein the adhesive is a pressure sensitive adhesive.

3. The retroreflective article of claim 2, wherein the pressure sensitive adhesive layer comprises a crosslinked tackified acrylic pressure sensitive adhesive.

4. The retroreflective article of claim 2, wherein the pressure sensitive adhesive comprises the reaction product of an acrylate ester of a non-tertiary alkyl alcohol, an acid comprising an ethylenically unsaturated moiety, and a crosslinking agent.

5. The retroreflective article of claim 1, wherein the first and second regions of the pigment-containing adhesive have sufficiently different properties to form the low refractive index layer between the first region of the adhesive layer and the structured surface of the retroreflective layer.

6. The retroreflective article of claim 1, wherein the pigment comprises TiO₂.

7. The retroreflective article of claim 1, wherein the first region is optically active and the second region is optically inactive.

8. The retroreflective article of claim 1, wherein the adhesive that contacts at least a portion of the structured surface forms an optically inactive area that does not substantially retroreflect incident light and the low refractive index layer between forms an optically active area that retroreflects incident light.

9. The retroreflective article of claim 1, wherein the adhesive layer is non-transparent.

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

11. The retroreflective article of claim 1, wherein the adhesive layer at the second region is in intimate contact with the structured surface and is white in color.

12. The retroreflective article of claim 1, wherein the first region differs in composition from the second region.

13. A method of forming the retroreflective article of claim 1, comprising:

applying the pigment-containing 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.

14. The method of claim 13, further comprising:

applying the barrier layer to the pigment-containing adhesive layer to form the first region.