Retroreflective sheeting including a low elastic modulus layer

Patent metadata

Field	Value
Publication number	US-10094960-B2
Application number	US-201414913250-A
Country	US
Kind code	B2
Filing date	Aug 13, 2014
Priority date	Aug 19, 2013
Publication date	Oct 9, 2018
Grant date	Oct 9, 2018

Abstract

The present application generally relates to retroreflective articles and methods of making retroreflective articles. Some embodiments include a body layer having an elastic modulus of equal to or greater than 1750 MPa, a plurality of truncated cube corner elements, and a polymeric layer between the body layer and the cube corner elements, the polymeric layer having an elastic modulus of less than 1750 MPa.

First claim

What is claimed is:

1. A retroreflective article, comprising:
a body layer comprising at least one of polymethylmethacrylate, PET (polyethylene terephthalate), polycarbonate, acrylic copolymers, and polyurethane, and having an elastic modulus of 1750 MPa or greater;
a plurality of truncated cube corner elements; and
a polymeric layer between the body layer and the cube corner elements, the polymeric layer having an elastic modulus that is less than 1750 MPa.

2. The retroreflective article of claim 1 , wherein the body layer has an elastic modulus of at least 3500 MPa.

3. The retroreflective article of claim 1 , wherein the body layer is biaxially oriented and includes at least one of polyethylene, polypropylene, polymethylmethacrylate, PET (polyethylene terephthalate), polycarbonate, acrylic copolymers, and polyurethane.

4. The retroreflective article of claim 1 , wherein the body layer has a thickness of between about 20 μm and about 1000 μm and the polymeric layer has a thickness of between about 0.2 mils and about 4 mils.

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

6. The retroreflective article of claim 1 , wherein the polymeric layer includes at least one of copolymers 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/isopthalate CoPET, polycarbonate, poly(vinyl chloride), ethylene acrylic acid, ethylene vinyl acetate, polyurethane, UV-cured acrylate or UV-cured epoxy acrylate polymers, or dispersions thereof.

7. 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.

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

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

10. 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.

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

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

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

14. A method of forming the retroreflective article of claim 1 , comprising:
providing a substrate comprising:
(a) the body layer having an elastic modulus of 1750 MPa or greater; and
(b) the polymeric layer having an elastic modulus that is less than 1750 MPa;

forming the plurality of truncated cube corner elements on the polymeric layer of the substrate.

15. The method of claim 14 , further comprising:
curing the retroreflective article.

Assignees

• 3M Innovative Properties Co

Inventors

• Chatterjee Reema
• Peterson Jeffrey A
• Gerlach Christopher P
• Meitz David W

Classifications

• G02B1/04

  made of organic materials, e.g. plastics (G02B1/08 takes precedence) · CPC title

• B29K2033/08

  Polymers of acrylic acid esters, e.g. PMA, i.e. polymethylacrylate · CPC title

• B29K2027/06

  PVC, i.e. polyvinylchloride · CPC title

• B29L2011/0083

  Reflectors · CPC title

• G02B5/124 Primary

  plural reflecting elements forming part of a unitary plate or sheet · CPC title