Brightness enhancement film comprising polymerized organic phase having low glass transition temperature

• US 7,943,206 B2
• Filed: 02/15/2006
• Issued: 05/17/2011
• Est. Priority Date: 02/17/2005
• Status: Active Grant

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Jones, Clinton L., Kolb, Brant U.
• Primary Examiner(s): McClendon; Sanza L
• Application Number:
  US11/814,088
• Publication Number:
  US 20080119583A1
• Time in Patent Office: 1,917 Days
• Field of Search: 522/71, 522/74, 522/77, 522/81, 522/90, 522/96, 522/113, 522/114, 522/120, 522/121, 522/150, 522/151, 522/152, 522/153, 522/173, 522/174, 522/178, 522/182, 428/1.1, 428/1.2, 428/1.51, 428/1.54, 428/1.55, 428/147, 428/148, 428/500, 523/202, 523/210
• US Class Current: 428/1.1
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: C08L 33/08 Homopolymers or copolymers of acrylic acid esters
• CPC Class Codes: C08L 33/10 Homopolymers or copolymers of methacrylic acid esters
• CPC Class Codes: C09K 2323/00 Functional layers of liquid crystal optical display excluding electroactive liquid crystal layer characterised by chemical composition
• CPC Class Codes: C09K 2323/02 Alignment layer characterised by chemical composition
• CPC Class Codes: C09K 2323/051 Inorganic, e.g. glass or silicon oxide
• CPC Class Codes: C09K 2323/057 Ester polymer, e.g. polycarbonate, polyacrylate or polyester
• CPC Class Codes: G02B 1/04 made of organic materials, e.g. plastics G02B1/08 takes precedence
• CPC Class Codes: G02B 6/0053 Prismatic sheet or layer; Brightness enhancement element, sheet or layer
• CPC Class Codes: Y10T 428/24405 Polymer or resin [e.g., natural or synthetic rubber, etc.]
• CPC Class Codes: Y10T 428/261 In terms of molecular thickness or light wave length
• CPC Class Codes: Y10T 428/31786 Of polyester [e.g., alkyd, etc.]
• CPC Class Codes: Y10T 428/31855 Of addition polymer from unsaturated monomers

Abstract

Microstructured articles such as brightness enhancing film and turning films having a (e.g. brightness enhancing) polymerized structure comprising the reaction product an organic phase and at least 10 wt-% inorganic nanoparticles. The reaction product of the organic phase has a glass transition temperature of less than 35° C.

Claims

1. A brightness enhancing film comprising

a brightness enhancing polymerized structure comprising the reaction product of an organic phase and at least 10 wt-% inorganic nanoparticles, wherein the organic phase consists of at least one oligomer or monomer that comprises at least two (meth)acrylate groups,

at least one monofunctional (meth)acrylate monomer, and optionally other (meth)acrylate monomers such that the reaction product of the organic phase has a glass transition temperature of less than 35°

C.

2. The brightness enhancing film of claim 1 wherein the amount of inorganic particles is less than about 60 wt-%.

3. The brightness enhancing film of claim 1 wherein the inorganic nanoparticles are polymerizable with the organic phase.

4. The brightness enhancing film of claim 1 wherein the inorganic nanoparticles comprise silica, zirconia, and mixtures thereof.

5. The brightness enhancing film of claim 1 wherein the inorganic nanoparticles comprise titania, antimony oxides, alumina, tin oxides, mixed metal oxides thereof, or mixtures thereof.

6. The brightness enhancing film of claim 1 wherein the primary particle ranges in size from 5 to 75 nm.

7. The brightness enhancing film of claim 1 wherein the primary particle ranges in size from 10 to 30 nm.

8. The brightness enhancing film of claim 1 wherein the primary particle ranges in size from 5 to 20 nm.

9. The brightness enhancing film according to claim 1 wherein the composition comprises a photoinitiator.

10. The brightness enhancing film of claim 1 wherein the polymerizable composition comprises 10 wt-% to 90 wt-% of urethane acrylate oligomer.

11. The brightness enhancing film of claim 1 wherein a viscosity of said polymerizable composition ranges from 10 cps to 35,000 cps at room temperature.

12. The brightness enhancing film according to claim 1, further comprising a base layer optically coupled to the polymerized structure.

13. The brightness enhancing film according to claim 12 wherein the base layer is a polarizing layer.

14. A device comprising:

(a) a lighting device having a light-emitting surface; and

(b) the brightness enhancing film of claim 1 placed substantially parallel to said light-emitting surface.

15. The device according to claim 14, wherein the lighting device is a back-lit display device or a liquid crystal display device.

16. The device according to claim 14, wherein the device is selected from a handheld device, a computer display and a television.

17. A microstructured article comprising the reaction product of an organic phase and at least 10 wt-% inorganic nanoparticles, wherein the organic phase consists of at least one oligomer or monomer that comprises at least two (meth)acrylate groups, at least one monofunctional (meth)acrylate monomer, and optionally other (meth)acrylate monomers such that the reaction product of the organic phase has a glass transition temperature of less than 35°

C.

18. The microstructured article of claim 17 wherein the article is a flexible mold suitable for making barrier ribs for a plasma display panel or retroreflective sheeting.