IP Library › Granted Patent US 9,618,663
Granted Patent B2
US 9,618,663 · App. 13/641,271 · Granted Apr 11, 2017

Retroreflective articles including optically active areas and optically inactive areas

Inventors: Kenneth L. Smith (White Bear Lake, MN); Michael Benton Free (St. Paul, MN); Bimal V. Thakkar (Woodbury, MN); Raymond C. Chiu (Woodbury, MN)
Assignee: 3M INNOVATIVE PROPERTIES COMPANY
G02B5/122B32B3/30G02B5/124
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Quick Facts
Patent No.
US 9,618,663
App. No.
13/641,271
Granted
Apr 11, 2017
Kind
B2
Abstract

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

Claims (24)

1. A retroreflective article, comprising:

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

a sealing layer having a first region and a second region, wherein the second region is in contact with the structured surface and wherein the second region surrounds the first region to form at least one cell with a cell size; and

wherein the sealing layer includes a barrier layer disposed within the first region between the sealing layer and the retroreflective layer separating a low refractive index layer from the sealing layer;

wherein the low refractive index layer is between the barrier layer of the first region and the structured surface of the retroreflective layer, wherein the first region has a cell size that is less than 1000 microns; and

wherein the CAP-Y is greater than 55.

2. The retroreflective article of claim 1 , wherein the cell size for the first region is less than 750 microns.

3. The retroreflective article of claim 1 , further including a seal leg that defines the first region.

4. The retroreflective article of claim 1 , wherein the retroreflective article exhibits a total light return that is not less than about 5% for incident visible light at an entrance angle of −4 degrees.

5. The retroreflective article of claim 1 , wherein the retroreflective article exhibits a coefficient of retroreflection R A that is not less than about 40 cd/(lux·m 2 ) for an observation angle of 0.2 degrees and an entrance angle of −4 degrees.

6. The retroreflective article of claim 1 , wherein the retroreflective article exhibits a coefficient of retroreflection R A that is not less than about 8 cpl for an observation angle of 2.0 degrees and an entrance angle of −4 degrees.

7. The retroreflective article of claim 1 , wherein the retroreflective article exhibits a % R T slope that is not less than about 3%/degree for an entrance angle of −4 degrees and an observation angle of 2 degrees.

8. The retroreflective article of claim 1 , wherein the retroreflective article exhibits a coefficient of retroreflection R A that is not less than about 4 cpl for an observation angle of 3.0 degrees and an entrance angle of −4 degrees.

9. The retroreflective article of claim 1 , wherein the retroreflective article exhibits a % R T slope that is not less than about 1.5%/degree for an entrance angle of −4 degrees and an observation angle of 3 degrees.

10. The retroreflective article of claim 1 , wherein less than about 65% of the structured surface is retroreflective.

11. The retroreflective article of claim 1 , wherein the cube corner elements are truncated cube corner elements.

12. The retroreflective article of claim 1 , wherein the sealing layer has a first region and a second region and wherein the second region is raised relative to the first region and is in contact with the structured surface.

13. The retroreflective article of claim 1 , wherein the retroreflective article exhibits a coefficient of retroreflection RA that is not less than about 40 cd/(lux m 2 ) for an observation angle of 0.2 degrees and an entrance angle of −4 degrees.

14. The retroreflective article of claim 1 , wherein the retroreflective article exhibits a coefficient of retroreflection RA that is not less than about 20 cpl for an observation angle of 1.0 degrees and an entrance angle of −4 degrees.

15. The retroreflective article of claim 1 , wherein the retroreflective article exhibits a % R T slope that is not less than about 9% degree for an entrance angle of −4 degrees and an observation angle of 1 degree.

16. The retroreflective article of claim 1 , wherein the retroreflective article exhibits a coefficient of retroreflection RA that is not less than about 8 cpl for an observation angle of 2.0 degrees and an entrance angle of −4 degrees.

17. The retroreflective article of claim 1 , wherein the retroreflective article exhibits a % R T slope that is not less than about 3%/degree for an entrance angle of −4 degrees and an observation angle of 2 degrees.

18. The retroreflective article of claim 1 , wherein the retroreflective article exhibits a % R T slope that is not less than about 1.5%/degree for an entrance angle of −4 degrees and an observation angle of 3 degrees.

19. The retroreflective article of claim 1 , comprising numerous cells that form one of an irregular pattern, a random pattern, a regular pattern, a grid, words, graphics, images, lines, and intersecting zones and wherein the distance between cells provides an angle of 1 arc minute or less when viewed at 20 feet.

Assignments (1)
ASSIGNMENT OF ASSIGNOR'S INTEREST Recorded Mar 21, 2013
From: SMITH, KENNETH L.; FREE, MICHAEL B; THAKKAR, BIMAL V.; CHIU, RAYMOND C.
To: 3M INNOVATIVE PROPERTIES COMPANY
Reel/Frame 030061/0428 →
Continuity (1)
Related Publication 20130135731A1 · May 30, 2013