Thin polarizing film, optical laminate with thin polarizing film, and production method for thin polarizing film

Patent metadata

Field	Value
Publication number	US-9227222-B2
Application number	US-201113813049-A
Country	US
Kind code	B2
Filing date	Sep 2, 2011
Priority date	Sep 3, 2010
Publication date	Jan 5, 2016
Grant date	Jan 5, 2016

Abstract

The present invention provides a thin polarizing film which has only a small environmental load and has excellent optical characteristics.
The thin polarizing film is produced by forming a polyvinyl alcohol-based resin layer on a thermoplastic resin substrate. The thin polarizing film has a thickness of 10 μm or less, a single axis transmittance of 42.0% or more, a polarization degree of 99.95% or more, and an iodine content of 17.6 grams per 400×700 square millimeters or less, which is measured by an ion chromatography method.

First claim

The invention claimed is:

1. A thin polarizing film, which is produced by forming a polyvinyl alcohol-based resin layer on a thermoplastic resin substrate,
wherein the thin polarizing film has a thickness of 10 μm or less, a single axis transmittance of 42.0% or more, a polarization degree of 99.95% or more, and an iodine content of 17.6 grams per 400×700 square millimeters or less, which is measured by an ion chromatography method.

2. A thin polarizing film according to claim 1 , wherein the thin polarizing film has a boric acid content of 1.5 grams per 400×700 square millimeters or less.

3. A method of producing a thin polarizing film as claimed in claim 1 , comprising:
forming a polyvinyl alcohol-based resin layer on a thermoplastic resin substrate to prepare a laminate;
dyeing the polyvinyl alcohol-based resin layer with iodine; and
subjecting the laminate to underwater stretching in an aqueous solution of boric acid.

4. A method of producing a thin polarizing film according to claim 3 , wherein a maximum stretching ratio of the laminate is 5.0 times or more.

5. A method of producing a thin polarizing film according to claim 3 , further comprising subjecting the laminate to in-air stretching at 95° C. or more before the dyeing and the boric acid underwater stretching.

6. A method of producing a thin polarizing film according to claim 4 , further comprising subjecting the laminate to in-air stretching at 95° C. or more before the dyeing and the boric acid underwater stretching.

Assignees

• Izaki Akinori
• Kitagawa Takeharu
• Goto Shusaku
• Kamijo Takashi
• Mori Tomohiro
• Miyatake Minoru
• Nitto Denko Corp

Inventors

• Izaki Akinori
• Kitagawa Takeharu
• Goto Shusaku
• Kamijo Takashi
• Mori Tomohiro
• Miyatake Minoru

Classifications

• C08J7/0427

  with only one layer of a composition containing a polymer binder (with more layers C08J7/042) · CPC title

• C08J2367/02

  Polyesters derived from dicarboxylic acids and dihydroxy compounds; (C08J2367/06 takes precedence) · CPC title

• G02F1/133528

  Polarisers · CPC title

• C08J2429/04

  Polyvinyl alcohol; Partially hydrolysed homopolymers or copolymers of esters of unsaturated alcohols with saturated carboxylic acids · CPC title

• G02B5/3033 Primary

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