Prismatic retroreflective article with fluorine- or silicon-containing prisms

• US 20060158736A1
• Filed: 12/28/2005
• Published: 07/20/2006
• Est. Priority Date: 12/28/2004
• Status: Active Grant

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Bacon, Chester A. Jr.
• Granted Patent: US 7,347,571 B2
• Time in Patent Office: Days
• US Class Current: 359/530
• CPC Class Codes: G02B 5/124 plural reflecting elements forming part of a unitary plate or sheet

Abstract

A prismatic retroreflective article comprising a transparent polymeric body portion having an elastic modulus less than about 13×10⁸ pascals, and a layer of internally reflecting open air-exposed cube-corner optical elements having an elastic modulus greater than about 14×10⁸ pascals and comprising a polymer having covalently-bound fluorine or silicon. The traditionally-employed rear cover film may be eliminated (thereby reducing cost, weight, stiffness and retroreflectivity loss due to seal leg formation), and retroreflectivity under wet conditions, dirty conditions, or both wet and dirty conditions can be at least partially maintained.

Claims

1. A prismatic retroreflective article comprising a transparent polymeric body portion having an elastic modulus less than about 13×

10⁸ pascals, and a layer of internally reflecting open air-exposed cube-corner optical elements having an elastic modulus greater than about 14×

10⁸ pascals and comprising a polymer having covalently-bound fluorine or silicon.

2. A retroreflective article according to claim 1, wherein the cube-corner optical elements comprise a fluoropolymer.

3. A retroreflective article according to claim 2, wherein the cube-corner optical elements comprise a perfluoroalkyl acrylate or methacrylate polymer or copolymer.

4. A retroreflective article according to claim 1, wherein the cube-corner optical elements comprise a polysiloxane.

5. A retroreflective article according to claim 4, wherein the cube-corner optical elements comprise a polyether-modified polydimethyl siloxane acrylate or methacrylate polymer or copolymer.

6. A retroreflective article according to claim 1, wherein the cube-corner optical elements are thermoplastic and comprise a fluorine-containing polymeric melt additive.

7. A retroreflective article according to claim 1, wherein the cube-corner optical elements are thermoplastic and comprise a silicon-containing polymeric melt additive.

8. A retroreflective article according to claim 1, wherein water or mineral oil will bead up rather than spreading when applied to the cube-corner optical elements.

9. A retroreflective article according to claim 1, wherein water and mineral oil will bead up rather than spreading when applied to the cube-corner optical elements.

10. A retroreflective article according to claim 1, further comprising a support on which the retroreflective article is mounted while leaving the cube-corner optical elements exposed to the open air.

11. A retroreflective article according to claim 10, wherein the support comprises a fabric.

12. A method for making a prismatic retroreflective article comprising providing a transparent body portion having an elastic modulus less than about 13×

10⁸ pascals, forming thereon a layer of internally reflecting open air-exposed cube-corner optical elements having an elastic modulus greater than about 14×

10⁸ pascals and comprising a polymer having covalently-bound fluorine or silicon, and leaving the cube-corner optical elements exposed to the open air.

13. A method according to claim 12, comprising forming the cube-corner optical elements from a polymerizable resin mixture comprising a copolymerizable fluorine-containing monomer, oligomer or polymer.

14. A method according to claim 13, wherein the polymerizable resin mixture comprises a perfluoroalkyl acrylate or methacrylate.

15. A method according to claim 14, wherein the perfluoroalkyl acrylate or methacrylate comprises methylperfluorobutylsulfonamido ethyl acrylate or methacrylate.

16. A method according to claim 12, comprising forming the cube-corner optical elements from a polymerizable resin mixture comprising a copolymerizable silicon-containing monomer, oligomer or polymer.

17. A method according to claim 16, wherein the polymerizable resin mixture comprises a polyether-modified polydimethyl siloxane.

18. A method according to claim 16, wherein the polymerizable resin mixture comprises a polyether-modified polydimethyl siloxane acrylate or methacrylate.

19. A method according to claim 12, comprising forming the cube-corner optical elements from a thermoplastic resin mixture comprising a fluorine-containing polymeric melt additive.

20. A method according to claim 12, comprising forming the cube-corner optical elements from a thermoplastic resin mixture comprising a silicon-containing polymeric melt additive.

21. A method according to claim 12, further comprising mounting the retroreflective article on a support while leaving the cube-corner optical elements exposed to the open air.

22. A method according to claim 21, wherein the support comprises a fabric.