Retroreflective sheeting including cube corner elements

• US 8,851,686 B2
• Filed: 03/14/2014
• Issued: 10/07/2014
• Est. Priority Date: 03/06/2003
• Status: Active Grant

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Smith, Kenneth L.
• Primary Examiner(s): CHERRY, EUNCHA P
• Application Number:
  US14/210,530
• Publication Number:
  US 20140198386A1
• Time in Patent Office: 207 Days
• Field of Search: 359/529, 359/530
• US Class Current: 359/529
• CPC Class Codes: B29C 59/007 Forming single grooves or ribs, e.g. tear lines, weak spots by moulding B29C37/0057; folding lines B29C53/06; in metal articles B21D17/00; by cutting B26D3/08
• CPC Class Codes: B29D 11/00605 Production of reflex reflectors
• CPC Class Codes: B29L 2011/0091 Reflex reflectors
• CPC Class Codes: G02B 1/10 Optical coatings produced by application to, or surface treatment of, optical elements G02B1/08 takes precedence
• CPC Class Codes: G02B 1/18 Coatings for keeping optical surfaces clean, e.g. hydrophobic or photo-catalytic films G02B1/16 takes precedence
• CPC Class Codes: G02B 5/122 cube corner, trihedral or triple reflector type
• CPC Class Codes: G02B 5/124 plural reflecting elements forming part of a unitary plate or sheet
• CPC Class Codes: Y10T 156/1082 Partial cutting bonded sandwich [e.g., grooving or incising]
• CPC Class Codes: Y10T 428/2457 Parallel ribs and/or grooves

Abstract

The present disclosure is directed to lamina(e) comprising cube corner elements, a tool comprising an assembly of laminae and replicas thereof. The disclosure further relates to retroreflective sheeting.

Claims

1. An article, comprising:

at least one preferred geometry cube corner element having three dihedral angles errors wherein the dihedral angle errors are different from each other; and

wherein the article exhibits at least one of the following average brightness measurements;

an average brightness at 0° and

90°

orientation according to ASTM D4596-1a of at least 625 candelas/lux/m² for an entrance angle of −

4° and

an observation angle of 0.2°

;

an average brightness at 0° and

90°

orientation according to ASTM D4596-1a of at least 575 candelas/lux/m² for an entrance angle of −

4° and

an observation angle of 0.33°

;

an average brightness at 0° and

90°

orientation according to ASTM D4596-1a of at least 375 candelas/lux/m² for an entrance angle of −

4° and

an observation angle of 0.5°

;

or

an average brightness at 0° and

90°

orientation according to ASTM D4596-1a of at least 80 candelas/lux/m² for an entrance angle of −

4° and

an observation angle of 1.0°

.

2. The article of claim 1, wherein the article exhibits an average brightness at 0°

and 90°

orientation according to ASTM D4596-1a of at least 625 candelas/lux/m² for an entrance angle of −

4° and

an observation angle of 0.2° and

at least 375 candelas/lux/m² for an entrance angle of −

4° and

an observation angle of 0.5°

.

3. The article of claim 1, wherein the article exhibits an average brightness at 0°

and 90°

orientation according to ASTM D4596-1a of at least 575 candelas/lux/m² for an entrance angle of −

4° and

an observation angle of 0.33°

, and at least 80 candelas/lux/m² for an entrance angle of −

4° and

an observation angle of 1.0°

.

4. The article of claim 1, wherein at least one preferred geometry cube corner element comprises a 1-2 dihedral angle error and a 1-3 dihedral angle error;

wherein the 1-2 dihedral angle error is the dihedral angle error of a dihedral angle formed between a side groove face and a face of the cube corner element that lies in a common plane with faces of multiple preferred geometry cube corner elements and the 1-3 dihedral angle error is the dihedral angle error of a dihedral angle formed between the other side groove face and the face of the cube corner element that lies in the common plane with faces of multiple preferred geometry cube corner elements.

5. The article of claim 4, wherein the 1-2 and 1-3 dihedral angle errors vary in opposition.

6. The article of claim 1, wherein the article is retroreflective sheeting.

7. The article of claim 6, wherein the retroreflective sheeting has a thickness of less than 0.020 inches.

8. The article of claim 6, wherein the preferred geometry cube corner elements are connected by a land layer.

9. The article of claim 8, wherein the land layer has a thickness between 0.003 inches and 0.010 inches.

10. The article of claim 6, further comprising:

a seal film that maintains an air interface at the faces of the preferred geometry cube corner elements; and

wherein the retroreflective sheeting exhibits an average brightness at 0° and

90°

orientation according to ASTM D4596-1a of at least 625 candelas/lux/m² for an entrance angle of −

4° and

an observation angle of 0.2°

, and at least 375 candelas/lux/m² for an entrance angle of −

4° and

an observation angle of 0.5°

.

11. The article of claim 6, further comprising:

a seal film that maintains an air interface at the faces of the preferred geometry cube corner elements; and

wherein the article exhibits an average brightness at 0° and

90°

orientation according to ASTM D4596-1a of at least 575 candelas/lux/m² for an entrance angle of −

4° and

an observation angle of 0.33°

, and at least 80 candelas/lux/m² for an entrance angle of −

4° and

an observation angle of 1.0°

.

12. The article of claim 1, wherein the article comprises at least one lamina comprising a plurality of side grooves in a working surface of the lamina, where each side groove comprises side groove faces, each side groove face corresponding to a face of a preferred geometry cube corner element.

13. The article of claim 1, wherein the cube corner elements have a lateral dimension of less than 0.020 inches.

14. The article of claim 13, wherein the cube corner elements have a lateral dimension of less than 0.007 inches.

15. The article of claim 1, wherein the preferred geometry cube corner elements have a shape in plan view that is selected from the group consisting of trapezoids, rectangles, or parallelograms.

16. The article of claim 1, wherein the preferred geometry cube corner elements have a shape in plan view that is a pentagon.

17. The article of claim 1, wherein the preferred geometry cube corner elements have a shape in plan view that is a hexagon.

18. The article of claim 1, wherein at least one of the preferred geometry cube corner elements is canted.

19. The article of claim 18, comprising two adjacent preferred geometry cube corner elements that are canted in different planes.

20. The article of claim 18, wherein the at least one preferred geometry cube corner element has a sideways cant component.

21. The article of claim 1, wherein the article comprises a plurality of side grooves having differing included angles.

22. The article of claim 21, wherein an included angle of a first side groove differ from an included angle of an adjacent side groove by at least 2°

.

23. The article of claim 21, wherein an include angle of a first side groove differs from an included angle of an adjacent side groove by at least 10°

.

24. The article of claim 21, wherein at least two adjacent side grooves are non-parallel by an amount that ranges from being greater than nominally parallel to non-parallel by less than 1°

.

25. The article of claim 1, further comprising:

a row of the preferred geometry cube corner elements, wherein a face of each of the preferred geometry cube corner elements in the row share a common plane.

26. The article of claim 25, wherein the common plane corresponds to a primary groove face.

27. The article of claim 25, wherein the common plane corresponds to a major surface of a lamina.

28. The article of claim 1, wherein the article comprises a plurality of side grooves and wherein at least two adjacent side grooves have differing inclination.

29. The article of claim 27, wherein a plurality of the side grooves have nonzero skew of 1°

or less.

30. The article of claim 1, wherein the dihedral angle errors are intentionally different from each other.

31. The article of claim 1, further comprising:

a plurality preferred geometry cube corner elements in a row, wherein at least one dihedral edge of each of the preferred geometry cube corner elements in a row range from being nominally parallel to nonparallel by less than 1°

.