Method for producing optical film, optical film, laminated polarizing plate, and image display

Patent metadata

Field	Value
Publication number	US-9581747-B2
Application number	US-201013376515-A
Country	US
Kind code	B2
Filing date	Jun 18, 2010
Priority date	Jun 19, 2009
Publication date	Feb 28, 2017
Grant date	Feb 28, 2017

Abstract

A method for producing an optical film including a birefringence layer having a refractive index distribution that satisfies nx>nz>ny, by which productivity of an optical film becomes high because there are a few steps, and a contamination is reduced, is provided. The method for producing an optical film including a birefringence layer includes forming an applied film by applying a birefringence layer forming material containing a non-liquid crystalline material with a birefringence (Δnxz) in the thickness direction thereof of 0.0007 or more directly on a shrinkable film, and forming a birefringence layer having a refractive index distribution that satisfies nx>nz>ny by shrinking the applied film through shrinking the shrinkable film.

First claim

The invention claimed is:

1. A method for producing an optical film, the method comprising:
forming an applied film by applying a solution containing a non-liquid crystalline material with a birefringence (Δnxz) in a thickness direction thereof, represented by the following formula, of 0.0007 or more directly on a shrinkable film; and then solidifying the solution to form the applied film; and
wherein the non-liquid crystalline material is at least one material selected from the group consisting of polyarylate, polyvinyl alcohol, polyfumaric acid ester, polyether sulfone, and polysulfone, and
forming a birefringence layer having a refractive index distribution that satisfies nx>nz>ny by shrinking the applied film through shrinking the shrinkable film,
wherein
Δ nxz=nx′−nz′

nx′: in a case where the non-liquid crystalline material is solidified so as to be a solidified layer, a refractive index in a direction (a slow axis direction) in which an in-plane refractive index of the solidified layer reaches its maximum,
nz′: a refractive index in a thickness direction of the solidified layer that is orthogonal to each of an nx′ direction and a direction (a fast axis direction) that is orthogonal to the nx′ direction within a plane of the solidified layer,
nx: a refractive index in a direction (a slow axis direction) in which an in-plane refractive index of the birefringence layer reaches its maximum,
ny: a refractive index in a direction (a fast axis direction) that is orthogonal to an nx direction within a plane of the birefringence layer, and
nz: a refractive index in a thickness direction of the birefringence layer that is orthogonal to each of the nx direction and an ny direction.

2. The method according to claim 1 , wherein the non-liquid crystalline material comprises polyarylate.

3. The method according to claim 2 , wherein the polyarylate includes repeating units represented by the following general formula (I),

where in the formula (I),
A and B each represents a substituent, are each a halogen atom, an alkyl group with a number of carbon atoms from 1 to 6, or a substituted or unsubstituted aryl group, and are identical to or different from each other,
a and b represent the numbers of substituents of A and B, respectively, and are each an integer from 1 to 4,
D is a covalent bond, a CH 2 group, a C(CH 3 ) 2 group, a C(CZ 3 ) 2 group (where Zs are halogen atoms), a CO group, an O atom, a S atom, a SO 2 group, a Si(CH 2 CH 3 ) 2 group, or a N(CH 3 ) group,
R1 is a straight chain or branched alkyl group with a number of carbon atoms from 1 to 10 or a substituted or unsubstituted aryl group,
R2 is a straight chain or branched alkyl group with a number of carbon atoms from 2 to 10 or a substituted or unsubstituted aryl group,
R3, R4, R5, and R6 are each a hydrogen atom or a straight chain or branched alkyl group with a number of carbon atoms from 1 to 4, are identical to or different from each other, and are not all hydrogen atoms,
p1 is an integer from 0 to 3,
p2 is an integer from 1 to 3, and
n is an integer of 2 or more.

4. The method according to claim 1 , wherein in the forming of the birefringence layer, a shrinkage ratio of the applied film is in a range from 0.50 to 0.99.

5. The method according to claim 1 , wherein in the forming of the birefringence layer, the applied film is shrunk through shrinking the shrinkable film, and a laminate of the shrinkable film and the applied film is stretched in a direction that is orthogonal to a shrinking direction.

6. The method according to claim 5 , wherein a stretch ratio of the laminate is in a range from 1.01 to 3.0.

7. The method according to claim 1 , wherein the shrinkable film is a stretchable film formed of at least one forming material selected from the group consisting of polyolefin, polyester, an acrylic resin, polyamide, polycarbonate, a norbornene resin, polystyrene, polyvinyl chloride, polyvinylidene chloride, a cellulose resin, polyether sulfone, polysulfone, polyimide, polyacryl, an acetate resin, polyarylate, polyvinyl alcohol, and a liquid crystal polymer.

8. The method according to claim 1 , wherein in the forming of the birefringence layer, the shrinkable film is shrunk by heating the shrinkable film.

9. The method according to claim 1 , wherein a thickness of the birefringence layer is 20 μm or less.

Assignees

• Iida Toshiyuki
• Kawasaki Motoko
• Murakami Nao
• Yoshimi Hiroyuki
• Nitto Denko Corp

Inventors

• Iida Toshiyuki
• Kawasaki Motoko
• Murakami Nao
• Yoshimi Hiroyuki

Classifications

• G02B5/3083 Primary

  Birefringent or phase retarding elements (G02B5/3008, G02B5/3016 take precedence; systems for polarisation control G02B27/286; manufacturing phase modulating patterns by lithographic processes G03F7/001) · CPC title

• C08L81/06

  Polysulfones; Polyethersulfones · CPC title

• G02F1/1335

  Structural association of cells with optical devices, e.g. polarisers or reflectors · CPC title

• G02B5/30 Primary

  Polarising elements (light-modulating devices with active elements G02F1/00) · CPC title