Polarizing film, pressure-sensitive-adhesive-layer-attached polarizing film, and image display device

• US 10,247,979 B2
• Filed: 09/29/2015
• Issued: 04/02/2019
• Est. Priority Date: 09/30/2014
• Status: Active Grant

• Current Assignee: Nitto Denko Corporation
• Original Assignee: Nitto Denko Corporation
• Inventors: Mita, Satoshi, Ueno, Tomonori, Motegi, Yusuke, Xu, Jingfan, Kishi, Atsushi
• Primary Examiner(s): Allen, Stephone B
• Assistant Examiner(s): Booher, Adam W
• Application Number:
  US15/515,890
• Publication Number:
  US 20170299920A1
• Time in Patent Office: 1,281 Days
• CPC Class Codes: C08K 3/38 Boron-containing compounds
• CPC Class Codes: C08K 5/0025 Crosslinking or vulcanising agents; including accelerators
• CPC Class Codes: C08L 29/04 Polyvinyl alcohol; Partially hydrolysed homopolymers or copolymers of esters of unsaturated alcohols with saturated carboxylic acids
• CPC Class Codes: C09J 129/04 Polyvinyl alcohol; Partially hydrolysed homopolymers or copolymers of esters of unsaturated alcohols with saturated carboxylic acids
• CPC Class Codes: C09J 133/02 Homopolymers or copolymers of acids; Metal or ammonium salts thereof
• CPC Class Codes: C09J 133/06 of esters containing only carbon, hydrogen and oxygen, the oxygen atom being present only as part of the carboxyl radical
• CPC Class Codes: G02B 5/3033 in the form of a thin sheet or foil, e.g. Polaroid
• CPC Class Codes: G02B 5/305 including organic materials, e.g. polymeric layers
• CPC Class Codes: G02F 1/133528 Polarisers
• CPC Class Codes: G02F 1/133632 with refractive index ellipsoid inclined relative to the LC-layer surface

Abstract

The present invention pertains to a polarizing film having a transparent layer on at least one surface of a polarizer, wherein: the polarizer contains a polyvinyl alcohol-based resin and has a thickness of 15 μm or less; the transparent layer-side of the polarizer has a compatible layer thereon having compatibility with the transparent layer; and the thickness A of the polarizer and the thickness B of the compatible layer satisfy the general formula (100×B/A)≥1. This polarizing film has crack resistance and suppresses changes in the dimensions of the polarizer.

Claims

1. A polarizing film comprising:

a polarizer comprising a polyvinyl alcohol-based resin and having a thickness of 15 μ

m or less;

a transparent layer provided on at least one surface of the polarizer and having a material capable of penetrating the polarizer; and

a compatible layer that is compatible with the transparent layer and provided in a transparent layer-side portion of the polarizer, wherein

the polarizer and the compatible layer have a thickness A and a thickness B, respectively, satisfying the general formula;

(100×

B/A)≥

1,

wherein the compatible layer is a portion of the polarizer having the material of the transparent layer penetrated therein.

2. The polarizing film according to claim 1, wherein the compatible layer has a boric acid concentration lower than that of a portion of the polarizer other than the compatible layer.

3. The polarizing film according claim 1, wherein the transparent layer has a thickness of 0.2 μ

m or more.

4. The polarizing film according to claim 1, wherein the transparent layer has a thickness of 6 μ

m or less.

5. The polarizing film according to claim 1, wherein the transparent layer has an orientation index of 0.05 or less.

6. The polarizing film according to claim 1, wherein the transparent layer is a product made from a layer-forming material comprising a polyvinyl alcohol-based resin.

7. The polarizing film according to claim 6, wherein the polyvinyl alcohol-based resin has a saponification degree of 99% by mole or more and an average degree of polymerization of 2,000 or more.

8. The polarizing film according to claim 1, wherein the polarizer is designed to have a single-body transmittance T and a polarization degree P representing optical properties satisfying the condition of the following formula:

P>

−

(10^0.0929T-42.4−

1)×

100 (provided that T<

42.3) or P≥

99.9 (provided that T≥

42.3).

9. The polarizing film according to claim 8, further comprising a protective film.

10. A pressure-sensitive-adhesive-layer-attached polarizing film comprising:

the polarizing film according to claim 1; and

a pressure-sensitive adhesive layer.

11. An image display device comprising the pressure-sensitive-adhesive-layer-attached polarizing film according to claim 10.

12. An image display device comprising the polarizing film according to claim 1.

13. A polarizing film comprising:

a polarizer comprising a polyvinyl alcohol-based resin and having a thickness of 15 μ

m or less;

a transparent layer provided on at least one surface of the polarizer; and

a low-boric-acid-concentration layer that is provided in a transparent layer-side portion of the polarizer and has a boric acid concentration lower than that of any other portion of the polarizer, wherein

the polarizer and the low-boric-acid-concentration layer have a thickness A and a thickness C, respectively, satisfying the general formula;

(100×

C/A)≥

1,

wherein the low-boric-acid-concentration layer is a portion of the polarizer.

14. The polarizing film according to claim 13, wherein the transparent layer has a thickness of 0.2 μ

m or more.

15. The polarizing film according to claim 13, wherein the transparent layer has a thickness of 6 μ

m or less.

16. The polarizing film according to claim 13, wherein the transparent layer has an orientation index of 0.05 or less.

17. The polarizing film according to claim 13, wherein the transparent layer is a product made from a layer-forming material comprising a polyvinyl alcohol-based resin.

18. The polarizing film according to claim 13, wherein the polarizer is designed to have a single-body transmittance T and a polarization degree P representing optical properties satisfying the condition of the following formula:

P>

−

(10^0.929T-42.4−

1)×

100 (provided that T<

42.3) or P≥

99.9 (provided that T≥

42.3).

19. The polarizing film according to claim 13, further comprising a protective film.

20. A pressure-sensitive-adhesive-layer-attached polarizing film comprising:

the polarizing film according to claim 13; and

a pressure-sensitive adhesive layer.

21. An image display device comprising the pressure-sensitive-adhesive-layer-attached polarizing film according to claim 20.

22. An image display device comprising the polarizing film according to claim 13.

23. The polarizing film according to claim 13, wherein a material of the transparent layer is capable of penetrating the polarizer.