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

Patent metadata

Field	Value
Publication number	US-9453953-B2
Application number	US-201514920322-A
Country	US
Kind code	B2
Filing date	Oct 22, 2015
Priority date	Sep 3, 2010
Publication date	Sep 27, 2016
Grant date	Sep 27, 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, comprising a polyvinyl alcohol-based resin film that adsorbs and orients an iodine,
wherein a polyvinyl alcohol-based resin that forms the polyvinyl alcohol-based resin film has a saponification degree of 99.0 mol % or more, and
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 the 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, comprising a polyvinyl alcohol-based resin film that adsorbs and orients an iodine,
Wherein the polyvinyl alcohol-based resin film is subjected to underwater stretching in an aqueous solution of boric acid, and
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 the iodine content of 17.6 grams per 400×700 square millimeters or less, which is measured by an ion chromatography method.

3. 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.

4. 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.

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

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

• 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

• G02B5/3033 Primary

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

• G02F1/133528

  Polarisers · CPC title

• G02F1/1335

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

• B29D11/00644

  polarizing · CPC title