Retroreflective sheeting including a substantially amorphous polymeric layer

Patent metadata

Field	Value
Publication number	US-9971074-B2
Application number	US-201414913269-A
Country	US
Kind code	B2
Filing date	Aug 14, 2014
Priority date	Aug 19, 2013
Publication date	May 15, 2018
Grant date	May 15, 2018

Abstract

The present application generally relates to retroreflective articles and methods of making retroreflective articles. The retroreflective articles include a substantially amorphous polymeric layer between the body layer and the discrete truncated cube corner elements. The substantially amorphous polymeric layer absorbs, dissipates, and/or accommodates at least some of the stress forces placed on the retroreflective article during processing. As a result, discrete truncated cube corner elements with increased fidelity can be formed. Consequently, retroreflective sheeting including a substantially amorphous polymeric layer has increased brightness compared to similarly made and composed sheeting lacking the substantially amorphous polymeric layer.

First claim

What is claimed is:

1. A retroreflective article, comprising:
a crystalline body layer;
a plurality of discrete truncated cube corner elements;
a substantially amorphous polymeric layer having a degree of crystallinity of less than 20% between the body layer and the cube corner elements.

2. The retroreflective article of claim 1 , wherein the body layer has an elastic modulus of at least 1750 MPa.

3. The retroreflective article of claim 1 , wherein the body layer has an elastic modulus of at least 2000 MPa.

4. The retroreflective article of claim 1 , wherein the body layer comprises at least one of polyethylene, polypropylene, polytetrafluoroethylene (PTFE), or nylon.

5. The retroreflective article of claim 1 , wherein the body layer is biaxially oriented and comprises at least one of polyethylene, polypropylene, PET (polyethylene terephthalate), polytetrafluoroethylene (PTFE), or nylon.

6. The retroreflective article of claim 1 , wherein the body layer has a thickness of between about 20 μm and about 1000 μm and the substantially amorphous polymeric layer has a thickness of between about 1.0 μm and about 100 μm.

7. The retroreflective article of claim 1 , wherein the substantially amorphous polymeric layer has an elastic modulus of less than 1750 MPa.

8. The retroreflective article of claim 1 , wherein the polymeric layer has an elastic modulus of less than 1500 MPa.

9. The retroreflective article of claim 1 , wherein the substantially amorphous polymeric layer comprises at least one an amorphous copolymer of poly(ethylene terephthalate) and poly(ethylene naphthalene dicarboxylate); poly(ethylene terephthalate) copolyester containing 1,4-cyclohexanedimethanol (PETG copolyester); poly(ethylene naphthalenedicarboxylate) copolyester containing 1,4-cyclohexanedimethanol (PEN copolyester); 80/20 terephthalate/isophthalate CoPET; polycarbonate; poly(vinyl chloride); poly(ethylene-co-acrylic acid); poly(ethylene-co-vinylacetate); polycarbonate; PMMA; or polyethylene terephthalate glycol.

10. The retroreflective article of claim 1 , further comprising a pressure sensitive adhesive layer that contacts the discrete truncated cube corner elements, the pressure sensitive adhesive layer comprising at least one discrete barrier layer.

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

12. The retroreflective article of claim 1 , wherein the polymeric layer comprises a biaxially oriented polymer.

13. The retroreflective article of claim 1 , further comprising:
a specular reflective layer adjacent to the cube corner elements.

14. The retroreflective article of claim 1 , wherein the article has a brightness of at least 250 candela/lux/m 2 .

15. The retroreflective article of claim 1 , wherein the retroreflective article is one of retroreflective sheeting, a highway signage article, a street signage article, a license plate sheeting, a license plate, a personal safety device, personal safety clothing, a conspicuity article, a vehicle warning article, or a canvas coating article.

16. The retroreflective article of claim 1 , wherein the polymeric layer B has a degree of crystallinity of less than 15%.

17. The retroreflective article of claim 1 , wherein the polymeric layer and the cube corner elements form an interpenetrating network.

18. The retroreflective article of claim 1 , wherein the substantially amorphous polymeric layer has a softening point of between about 45° C. and 160° C.

19. A method of forming a retroreflective article of claim 1 , comprising:
providing a substrate comprising:
the body layer; and
the polymeric layer comprising the substantially amorphous polymer;

casting the plurality of discrete truncated cube corner elements on the polymeric layer of the substrate; and
curing the resulting retroreflective article.

Assignees

• 3M Innovative Properties Co

Inventors

• Chatterjee Reema
• Johnson Stephen A
• Watkins Robert F
• Thakkar Bimal V

Classifications

• B32B7/12

  using interposed adhesives or interposed materials with bonding properties · CPC title

• B32B2307/518

  bi-axially · CPC title

• B29D11/00605

  Production of reflex reflectors · CPC title

• B32B2307/702

  Amorphous · CPC title

• B32B27/365

  comprising polycarbonates · CPC title