Optical article having viscoelastic layer

• US 9,684,120 B2
• Filed: 12/10/2015
• Issued: 06/20/2017
• Est. Priority Date: 02/10/2010
• Status: Expired due to Fees

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Wolk, Martin B., Sykora, Michael J., Brott, Robert L., Meis, Michael A., Schultz, John C., Mazurek, Mieczyslaw H., Bryan, William J., Schaffer, Kevin R., Aho, Erik A., Kristoffersen, Martin, Sherman, Audrey A.
• Primary Examiner(s): TSO, LAURA K
• Application Number:
  US14/965,250
• Publication Number:
  US 20160097895A1
• Time in Patent Office: 558 Days
• Field of Search: 362623
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: G02B 6/0001 specially adapted for lighting devices or systems lighting or signalling on vehicles using light guides B60Q1/00; lighting devices for vehicle dashboards B60Q3/10; lighting devices for vehicle interior using light guides B60Q3/62; lighting devices mounted on the vehicle rear part using light guides F21S43/235; measuring arrangements having light conducting pointers G01D13/265; illumination of liquid crystal displays G02F1/1336; illuminated signs G09F13/00
• CPC Class Codes: G02B 6/0035 provided on the surface of the light guide or in the bulk of it
• CPC Class Codes: G02B 6/0036 2-D arrangement of prisms, protrusions, indentations or roughened surfaces
• CPC Class Codes: G02B 6/0038 Linear indentations or grooves, e.g. arc-shaped grooves or meandering grooves, extending over the full length or width of the light guide
• CPC Class Codes: G02B 6/005 provided by one optical element, or plurality thereof, placed on the light output side of the light guide
• CPC Class Codes: G02B 6/0051 Diffusing sheet or layer
• CPC Class Codes: G02B 6/0065 Manufacturing aspects; Material aspects
• CPC Class Codes: Y10S 977/78 Possessing fully enclosed nanosized voids or physical holes
• CPC Class Codes: Y10S 977/932 for electronic or optoelectronic application

Abstract

An optical article, such as a backlight for electronic display devices, is disclosed. The optical article includes a lightguide, a viscoelastic layer disposed on the light guide and a nanovoided polymeric layer disposed on the viscoelastic layer. The nanovoided polymeric layer comprises a plurality of interconnected nanovoids and at least some of the interconnected nanovoids are connected to one another by hollow passages. The lightguide may be optically coupled to a light source, and the viscoelastic layer and the nanovoided polymeric layer may be used in conjunction with the lightguide to manage light emitted by the light source. The viscoelastic layer may be a pressure sensitive adhesive.

Claims

1. An optical article comprising:

a lightguide,

a viscoelastic layer disposed on a major surface of the lightguide, and

a nanovoided polymeric layer disposed on the viscoelastic layer opposite the lightguide, the nanovoided polymeric layer comprising a plurality of interconnected nanovoids, at least some of the interconnected nanovoids connected to one another by hollow passages.

2. The optical article of claim 1, the nanovoided polymeric layer comprising a binder and a plurality of nanoparticles, wherein a weight ratio of the binder to the plurality of nanoparticles is greater than about 1:

2, and a volume fraction of the interconnected nanovoids in the nanovoided polymeric layer is not less than about 20%.

3. The optical article of claim 2, wherein a weight ratio of the binder to the plurality of nanoparticles ranges from about 30:

70 to about 90;

10.

4. The optical article of claim 2, wherein the binder is crosslinked.

5. The optical article of claim 2, wherein the binder comprises a multifunctional (meth)acrylate and a urethane oligomer.

6. The optical article of claim 1, the nanovoided polymeric layer further comprising beads having an average diameter that is greater than a thickness of the nanovoided polymeric layer.

7. The optical article of claim 1, wherein the nanovoided polymeric layer has a thickness of less than about 5 micrometers.

8. The optical article of claim 1, wherein the viscoelastic layer comprises a pressure sensitive adhesive.

9. The optical article of claim 1, wherein:

the viscoelastic layer comprises a (meth)acrylic pressure sensitive adhesive, the (meth)acrylic pressure sensitive adhesive comprising

a first monomer comprising a monoethylenically unsaturated alkyl (meth)acrylate monomer, and

a second monomer wherein a homopolymer of the second monomer has a Tg of at least about 10°

C.

10. The optical article of claim 1, wherein the viscoelastic layer comprises a silicone pressure sensitive adhesive.

11. The optical article of claim 1, wherein the viscoelastic layer comprises a stretch releasable pressure sensitive adhesive.

12. The optical article of claim 1, wherein the viscoelastic layer comprises a (meth)acrylate, rubber, silicone, urethane, or a combination thereof.

13. The optical article of claim 1, wherein a 90°

peel adhesion between the viscoelastic layer and the lightguide is from about 190 N/m (500 g/in) to about 1160 N/m (3000 g/in).

14. The optical article of claim 1, wherein the lightguide comprises a polymeric material or glass.

15. The optical article of claim 1, wherein the lightguide comprises a liquid.

16. The optical article of claim 1, the viscoelastic layer having a refractive index greater than that of the lightguide.

17. The optical article of claim 1, the viscoelastic layer having a refractive index less than that of the lightguide.

18. The optical article of claim 1, wherein the difference in refractive indices for the viscoelastic layer and the lightguide is less than about 0.05.

19. The optical article of claim 1, wherein an interface formed between the lightguide and the viscoelastic layer comprises a plurality of features.

20. The optical article of claim 19, wherein the features comprise at least one of a plurality of prisms and a plurality of lenses.

21. The optical article of claim 1, wherein an interface formed between the nanovoided polymeric layer and the viscoelastic layer comprises a plurality of features.

22. The optical article of claim 21, wherein the features comprise at least one of a plurality of prisms and a plurality of lenses.

23. The optical article of claim 1, further comprising an additional layer disposed on the nanovoided polymeric layer opposite the viscoelastic layer.

24. The optical article of claim 23, the additional layer comprising a release liner.

25. The optical article of claim 1, wherein the interconnected nanovoids have an average size of less than about 0.7 micrometers.

26. An illumination device comprising the optical article of claim 1 and a light source, wherein the light source is configured to inject light into an input surface of the lightguide and the optical article is configured such that the injected light is transported within the lightguide by total internal reflection.

27. An illumination device comprising:

a light source; and

an optical article comprising;

a lightguide optically coupled to the light source,

a viscoelastic layer disposed on the lightguide,

a nanovoided polymeric layer disposed on the viscoelastic layer opposite the lightguide, the nanovoided polymeric layer comprising a plurality of interconnected nanovoids, at least some of the interconnected nanovoids connected to one another by hollow passages, and

an adhesive layer disposed on the nanovoided polymeric layer opposite the viscoelastic layer.

28. The illumination device of claim 27, the optical article further comprising a release liner disposed on the adhesive layer opposite the nanovoided layer.

29. The illumination device of claim 27, wherein the interconnected nanovoids have an average size of less than about 0.7 micrometers.