Microstructured film comprising nanoparticles and monomer comprising alkylene oxide repeat units

• US 9,360,591 B2
• Filed: 08/22/2013
• Issued: 06/07/2016
• Est. Priority Date: 09/20/2012
• Status: Active Grant

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Hunt, Bryan V., Nelson, Maureen C., Nelson, Eric W., Olson, David B., Pokorny, Richard J.
• Primary Examiner(s): Mai, Anh
• Assistant Examiner(s): ZIMMERMAN, GLENN D
• Application Number:
  US14/426,440
• Publication Number:
  US 20150241599A1
• Time in Patent Office: 1,020 Days
• Field of Search: 362/327, 362/326, 362/339, 362/337, 362/618, 362/619, 362/620, 428/1.33, 428/1.54
• US Class Current: 1/1
• CPC Class Codes: B32B 2457/20 Displays, e.g. liquid crystal displays, plasma displays
• CPC Class Codes: C08F 220/10 Esters
• CPC Class Codes: C08J 2333/08 Homopolymers or copolymers of acrylic acid esters
• CPC Class Codes: C08J 5/18 Manufacture of films or sheets
• CPC Class Codes: C08K 3/22 of metals
• CPC Class Codes: C08L 2203/16 used for films
• CPC Class Codes: C08L 2666/54 Inorganic substances
• CPC Class Codes: C08L 33/06 of esters containing only carbon, hydrogen and oxygen, which oxygen atoms are present only as part of the carboxyl radical
• 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: F21V 13/04 the elements being reflectors and refractors for vehicle rear lights F21S43/40
• CPC Class Codes: F21V 5/02 of prismatic shape F21V5/04 takes precedence
• CPC Class Codes: G02B 1/04 made of organic materials, e.g. plastics G02B1/08 takes precedence
• CPC Class Codes: G02B 5/0231 the surface having microprismatic or micropyramidal shape macroscopic prism arrays G02B5/045
• CPC Class Codes: G02B 6/0053 Prismatic sheet or layer; Brightness enhancement element, sheet or layer
• CPC Class Codes: G02B 6/0065 Manufacturing aspects; Material aspects
• CPC Class Codes: G02F 1/133502 Antiglare, refractive index matching layers
• CPC Class Codes: G02F 1/133507 Films for enhancing the luminance
• CPC Class Codes: G02F 2202/36 Micro- or nanomaterials

Abstract

Presently described are microstructured films, such as brightness enhancing films, having a microstructured surface. The microstructured surface comprises the reaction product of a polymerizable composition comprising at least 20 wt-% of inorganic nanoparticles and a non-aromatic multi-(meth)acrylate monomer comprising at least three contiguous alkylene oxide repeat units. The multi-(meth)acrylate monomer typically comprises two or three (meth)acrylate groups. The alkylene oxide repeat units have the formula —[O-L]- wherein each L is independently a C₂-C₆ alkylene. Also described is a polymerizable resin composition comprising at least 20 wt-% of inorganic nanoparticles having a refractive index of at least 1.68 and a non-aromatic multi-(meth)acrylate monomer comprising at least three contiguous alkylene oxide repeat units.

Claims

1. A brightness enhancing film having a microstructured surface comprising a plurality of prisms, wherein the microstructured surface comprises the reaction product of a polymerizable composition comprising

at least 20 wt-% of inorganic nanoparticles having a refractive index of at least 1.68,

a non-aromatic multi-(meth)acrylate monomer comprising at least three contiguous alkylene oxide repeat units, and

mono(meth)acrylate diluent selected from biphenyl or benzyl monomer.

2. The brightness enhancing film of claim 1 wherein the multi-(meth)acrylate monomer comprises two or three (meth)acrylate groups.

3. The brightness enhancing film of claim 1 wherein the alkylene oxide repeat units have the formula —

[O-L]- wherein each L is independently a C₂-C₆ alkylene.

4. The brightness enhancing film of claim 1 wherein the multi-(meth)acrylate monomer is a di(meth)acrylate comprising at least 5 contiguous alkylene oxide repeat units.

5. The brightness enhancing film of claim 1 wherein the multi-(meth)acrylate monomer is a tri(meth)acrylate comprising a total of at least 10 alkylene oxide repeat units.

6. The brightness enhancing film of claim 1 wherein the multi-(meth)acrylate monomer has the general formula:

7. The brightness enhancing film of claim 1 wherein the alkylene oxide repeat units comprise ethylene oxide repeat units, propylene oxide repeat units, or a mixture thereof.

8. The brightness enhancing film of claim 1 wherein the polymerizable composition comprises 3 to 75 wt-% of the multi-(meth)acrylate monomer comprising alkylene oxide repeat units.

9. The brightness enhancing film of claim 1 wherein the polymerizable composition further comprises a crosslinker comprising at least three (meth)acrylate groups.

10. The brightness enhancing film of claim 1 wherein the crosslinker concentration is no greater than about 25 wt-% of the polymerizable composition.

11. The brightness enhancing film of claim 1 wherein the polymerizable composition comprises at least 5 wt-% crosslinker.

12. The brightness enhancing film of claim 1 wherein the polymerizable composition is free of crosslinker.

13. The brightness enhancing film of claim 1 wherein the biphenyl monomer has the general formula:

14. The brightness enhancing film of claim 1 wherein the benzyl monomer has the general formula:

15. The brightness enhancing film of claim 1 wherein the amount of inorganic nanoparticles ranges from 40 wt-% to 60 wt-% of the polymerizable composition.

16. The brightness enhancing film of claim 1 wherein the polymerizable resin has a refractive index of at least 1.56.

17. The brightness enhancing film of claim 1 wherein the inorganic nanoparticles comprise zirconia.

18. The brightness enhancing film of claim 1 wherein the inorganic nanoparticles comprise a surface treatment comprising a carboxylic acid end group and at least one C₃-C₁₆ ester unit.

19. The brightness enhancing film of claim 1 wherein the surface treatment comprises the reaction product of

i) at least one aliphatic anhydride, and

ii) at least one hydroxy polycaprolactone (meth)acrylate.

20. The brightness enhancing film of claim 1 wherein the brightness enhancing film has a ball drop damage contrast of no greater than 0.25.

21. The brightness enhancing film of claim 9 wherein the crosslinker has a molecular weight per (meth)acrylate group of no greater than 150 g/mole.

22. The brightness enhancing film of claim 9 wherein the crosslinker comprises trimethylol propane (meth)acrylate, ethoxylated (3) trimethylol propane (meth)acrylate, or a mixture thereof.

23. The brightness enhancing film of claim 9 wherein the mono(meth)acrylate diluent has a refractive index of at least 1.55.

24. The brightness enhancing film of claim 9 wherein the polymerizable composition comprises 10 to 60 wt-% of mono(meth)acrylate diluents(s).

25. The brightness enhancing film of claim 18 wherein the surface treatment has the general formula:

26. The brightness enhancing film of claim 25 wherein Z comprises a (meth)acrylate end group.