# US 8,772,400 B2 · Polyvinyl alcohol-based film for optical use, polarizing film, and polarizing plate

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- Number: US 8,772,400 B2
- Document ID: US8772400B2
- Status: Granted
- Kind: B2
- Application number: 12/309,657
- Filed: 2006-07-27
- Published: 2009-12-24
- Granted: 2014-07-08
- Earliest claimed: 2006-07-27
- Assignees: The Nippon Synthetic Chemical Industry Co., Ltd.
- Applicants: Shuichi Kitamura; Katsuhiko Katsuma; Mitsuo Shibutani; Toshihiro Shimizu
- Inventors: Shuichi Kitamura; Katsuhiko Katsuma; Mitsuo Shibutani; Toshihiro Shimizu
- Web page: https://patentgrep.com/patent/US8772400B2

## CPC

- G02B 5/3033: {in the form of a thin sheet or foil, e.g. Polaroid}
- C08J 5/18: Manufacture of films or sheets
- C08L 29/04: Polyvinyl alcohol; Partially hydrolysed homopolymers or copolymers of esters of unsaturated alcohols with saturated carboxylic acids
- C08J 2329/04: Polyvinyl alcohol; Partially hydrolysed homopolymers or copolymers of esters of unsaturated alcohols with saturated carboxylic acids
- C08L 2205/02: containing two or more polymers of the same C08L -group
- Y10T 428/26: Web or sheet containing structurally defined element or component, the element or component having a specified physical dimension
- Y10T 428/261: In terms of molecular thickness or light wave length
- Y10T 428/2967: Synthetic resin or polymer
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- C08J: WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H (working, e.g. shaping, of plastics B29)
- C08L: COMPOSITIONS OF MACROMOLECULAR COMPOUNDS (compositions based on polymerisable monomers C08F, C08G; artificial filaments or fibres D01F; textile treating compositions D06)
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

The present invention provides a polyvinyl alcohol-based film for optical uses, which is excellent in stretching property and is used for producing a polarizing film excellent in polarization performance throughout the visible light wavelength range, particularly in the vicinity of the wavelength of 460 nm. The invention relates to a polyvinyl alcohol-based film for optical uses comprising a polyvinyl alcohol-based resin, wherein the polyvinyl alcohol-based resin is composed of only a polyvinyl alcohol-based resin (A) containing a 1,2-glycol bond at a side chain and the amount of the 1,2-glycol bond at a side chain is from 0.01 to 6% by mol, or a polyvinyl alcohol-based film for optical uses comprising a polyvinyl alcohol-based resin, wherein the polyvinyl alcohol-based resin includes a polyvinyl alcohol-based resin (A) containing a 1,2-glycol bond at a side chain and a polyvinyl alcohol-based resin (B) other than the polyvinyl alcohol-based resin (A) and satisfies the following expression (1): 0.01≦A×G/(A+B)≦6 (1) wherein A represents a content ratio (weight ratio) of the polyvinyl alcohol-based resin (A) based on a total amount of the polyvinyl alcohol-based resin (A) and the polyvinyl alcohol-based resin (B), B represents a content ratio (weight ratio) of the polyvinyl alcohol-based resin (B) based on the above total amount, and G represents an amount (% by mol) of the 1,2-glycol bond at a side chain.

## Claims

### Claim 1

A polyvinyl alcohol-based film comprising a polyvinyl alcohol-based resin,
the polyvinyl alcohol-based resin comprising:
a polyvinyl alcohol-based resin (A) containing a 1,2-glycol bond at a side chain; and
a polyvinyl alcohol-based resin (B) other than the polyvinyl alcohol-based resin (A), having a degree of saponification of 98% by mol or more,
wherein a difference in a degree of saponification between the polyvinyl alcohol-based resin (A) and the polyvinyl alcohol-based resin (B) is in a range of 3% by mol or less,
a content of the polyvinyl alcohol-based resin (A) is 5 to 30% by weight relative to a total amount of the polyvinyl alcohol-based resin (A) and the polyvinyl alcohol-based resin (B), and
the polyvinyl alcohol-based resin satisfies the following expression (1):
0.01≦A×G/(A+B)≦6 (1),
wherein A represents the content (weight %) of the polyvinyl alcohol-based resin (A) relative to the total amount of the polyvinyl alcohol-based resin (A) and the polyvinyl alcohol-based resin (B), B represents a content (weight %) of the polyvinyl alcohol-based resin (B) relative to the total amount of the polyvinyl alcohol-based resin (A) and the polyvinyl alcohol-based resin (B), and G represents an amount (mol %) of the 1,2-glycol bond at a side chain.

### Claim 2 (depends on 1)

The polyvinyl alcohol-based film according to claim 1, wherein a viscosity of the polyvinyl alcohol-based resin (A) is from 8 to 400 mPa·s as a viscosity of a 4% by weight aqueous solution.

### Claim 3 (depends on 1)

The polyvinyl alcohol-based film according to claim 1, wherein a viscosity of the polyvinyl alcohol-based resin (B) is from 8 to 500 mPa·s as a viscosity of a 4% by weight aqueous solution.

### Claim 4 (depends on 1)

The polyvinyl alcohol-based film according to claim 1, which further contains a plasticizer (C).

### Claim 5 (depends on 1)

The polyvinyl alcohol-based film according to claim 1, which further contains a surfactant (D).

### Claim 6 (depends on 1)

The polyvinyl alcohol-based film according to claim 1, wherein a width of the film is 2 m or more.

### Claim 7 (depends on 1)

The polyvinyl alcohol-based film according to claim 1, wherein a thickness of the film is from 30 to 70 μm.

### Claim 8 (depends on 1)

A polarizing film comprising the polyvinyl alcohol-based film according to claim 1.

### Claim 9 (depends on 8)

A polarizing plate comprising the polarizing film according to claim 8 and a protective film provided on at least one surface of the polarizing film.