Polarizing film and method for producing polarizing film

Patent metadata

Field	Value
Publication number	US-9658366-B2
Application number	US-201314425760-A
Country	US
Kind code	B2
Filing date	Oct 11, 2013
Priority date	Oct 22, 2012
Publication date	May 23, 2017
Grant date	May 23, 2017

Abstract

Provided is a polarizing film that is excellent in external appearance and can contribute to improving the display characteristics of an image display apparatus. A polarizing film of the present invention includes a polyvinyl alcohol-based resin film containing iodine. At least one surface side of the polyvinyl alcohol-based resin film includes a low-iodine layer.

First claim

The invention claimed is:

1. A polarizing film, comprising a polyvinyl alcohol-based resin film dyed substantially with only iodine,
wherein at least one surface side of the polyvinyl alcohol-based resin film comprises a low content iodine layer.

2. The polarizing film according to claim 1 , wherein the polyvinyl alcohol-based resin film has a thickness of 7 μm or less.

3. The polarizing film according to claim 1 , wherein a surface of the polyvinyl alcohol-based resin film on the low content iodine layer side has an anisotropic reflection determined from the following equation (1) at a wavelength of 680 nm of 1.50 or less:
anisotropic reflection= Rc/Rp   (1)

where:
Rp represents a reflectance in the transmission axis direction of the polarizing film, and
Rc represents a reflectance in the absorption axis direction of the polarizing film.

4. A manufacturing method for the polarizing film of claim 1 , the manufacturing method comprising bringing a treatment liquid containing a water-soluble antioxidant into contact with at least a surface of a polyvinyl alcohol-based resin membrane dyed with the iodine.

5. The manufacturing method according to claim 4 , wherein the water-soluble antioxidant contains at least any one kind of ascorbic acid, thiosulfuric acid, and salts thereof.

6. The manufacturing method according to claim 4 , wherein the treatment liquid has an absorbance of light having a wavelength of 350 nm of substantially zero.

7. The manufacturing method according to claim 4 , wherein the polyvinyl alcohol-based resin membrane comprises a polyvinyl alcohol-based resin layer formed on a resin substrate.

8. An image display apparatus, comprising the polarizing film of claim 1 ,
wherein the polarizing film is arranged so that a surface on the low content iodine layer side of the polarizing film is on a viewer side.

9. A manufacturing method for a polarizing film comprising a polyvinyl alcohol-based resin film dyed substantially with only iodine, wherein at least one surface side of the polyvinyl alcohol-based resin film comprises a low content iodine layer, the manufacturing method comprising:
bringing a treatment liquid containing a water-soluble antioxidant into contact with at least a surface of a polyvinyl alcohol-based resin membrane dyed with the iodine;
subjecting the polyvinyl alcohol-based resin membrane to underwater stretching,
wherein the treatment with the water-soluble antioxidant is performed after the underwater stretching.

10. A manufacturing method for a polarizing film comprising a polyvinyl alcohol-based resin film dyed substantially with only iodine, wherein at least one surface side of the polyvinyl alcohol-based resin film comprises a low content iodine layer, the manufacturing method comprising:
bringing a treatment liquid containing a water-soluble antioxidant into contact with at least a surface of a polyvinyl alcohol-based resin membrane dyed with the iodine;
stretching the polyvinyl alcohol-based resin membrane by adopting only an in-air stretching mode,
wherein the treatment liquid has a temperature of 50° C. or more.

Assignees

• Nitto Denko Corp

Inventors

• Goto Shusaku
• Ogomi Daisuke
• Nakano Yuki
• Yasen Muniridin
• Kaneko Osamu

Classifications

• G02B1/08 Primary

  made of polarising materials · CPC title

• G02B5/3033

  in the form of a thin sheet or foil, e.g. Polaroid · CPC title

• G02B1/111 Primary

  using layers comprising organic materials · CPC title

• G02F1/133528

  Polarisers · CPC title