Microstructured film comprising nanoparticles and monomer comprising alkylene oxide repeat units

Patent metadata

Field	Value
Publication number	US-9360591-B2
Application number	US-201314426440-A
Country	US
Kind code	B2
Filing date	Aug 22, 2013
Priority date	Sep 20, 2012
Publication date	Jun 7, 2016
Grant date	Jun 7, 2016

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 C 2 -C 6 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.

First claim

What is claimed is:

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 C 2 -C 6 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:

wherein R1 is H or methyl, R2 is a trivalent organic residue, L is independently a C 2 to C 6 alkylene, and n is 3 to 30.

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:

wherein R1 is H or CH 3 ;
X is O or S;
Q is selected from —(C(CH 3 ) 2 —, —CH 2 , —C(O)—, —S(O)—, and —S(O) 2 —;
n ranges from 0 to 10 (e.g. n is 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10); and
L is an alkylene group having 1 to 5 carbon atoms, optionally substituted with hydroxy.

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

wherein at least one R1 comprises an aromatic substituent,
t is an integer from 1 to 4; and
R2 is hydrogen or methyl.

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 C 3 -C 16 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:

wherein
n averages from 1.1 to 6;
L1 is a C 1 -C 8 alkylene, arylalkylene, or arylene group, optionally substituted with one or more oxygen atoms or an ester group;
L2 is a C 3 -C 8 alkylene, arylalkylene, or arylene group, optionally substituted with one or more oxygen atoms;
Y is

and
Z is an end group comprising a C 2 -C 8 alkyl, ether, ester, alkylene oxide, (meth)acrylate, or combination thereof.

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

Assignees

• 3M Innovative Properties Co

Inventors

• Hunt Bryan V
• Nelson Maureen C
• Nelson Eric W
• Olson David B
• Pokorny Richard J

Classifications

• F21V5/02

  of prismatic shape (F21V5/04 takes precedence) · CPC title

• C08K3/22

  of metals · CPC title

• C08F220/10

  Esters · CPC title

• F21V13/04

  the elements being reflectors and refractors {(for vehicle rear lights F21S43/40)} · CPC title

• G02B6/0053

  Prismatic sheet or layer; Brightness enhancement element, sheet or layer · CPC title