Polarizer, polarizing plate, and liquid crystal display using the same

• US 20050260392A1
• Filed: 02/19/2004
• Published: 11/24/2005
• Est. Priority Date: 06/19/2000
• Status: Abandoned Application

• Current Assignee: Nitto Denko Corporation
• Original Assignee: Nitto Denko Corporation
• Inventors: Sugino, Youichirou, Tsuchimoto, Kazuki, Kusumoto, Seiichi, Saiki, Yuuji, Hamamoto, Eiji, Kondou, Senri, Mihara, Hisashi
• Application Number:
  US10/780,668
• Publication Number:
  US 20050260392A1
• Time in Patent Office: Days
• US Class Current: 428/212
• CPC Class Codes: C09K 2323/031 Polarizer or dye
• CPC Class Codes: G02B 5/3033 in the form of a thin sheet or foil, e.g. Polaroid
• CPC Class Codes: G02B 7/008 with means for compensating for changes in temperature or for controlling the temperature; thermal stabilisation
• CPC Class Codes: G02F 1/133528 Polarisers
• CPC Class Codes: G02F 2201/50 Protective arrangements
• CPC Class Codes: G02F 2201/54 Arrangements for reducing warping-twist
• CPC Class Codes: Y10T 428/24942 including components having same physical characteristic in differing degree
• CPC Class Codes: Y10T 428/3188 Next to cellulosic
• CPC Class Codes: Y10T 428/31935 Ester, halide or nitrile of addition polymer

Abstract

The present invention provides a polarizer and a polarizing plate having less dimensional changes to heat stress. The present invention provides also a liquid crystal display that includes the polarizer and the polarizing plate, and is free of color irregularity or decoloration. The polarizer has shrinkage force of not more than 4.0 N/cm in the absorption axis direction after being heated at 80° C. for 30 minutes. A protective film is laminated on at least one surface of the polarizer in order to form a polarizing plate, and the polarizing plate has a following relationship of 0.01≦A/B≦0.16 when A denotes a thickness of the polarizer and B denotes a thickness of the protective film.

Claims

1. A polarizing plate comprising:

a polarizer formed with a hydrophilic polymer film and

a protective film laminated on at least one surface of the polarizer,

wherein the polarizing plate satisfies a relationship of 0.01≦

A/B≦

0.16 where A denotes a thickness of the polarizer and B denotes a thickness of the protective film.

2. The polarizing plate according to claim 1, satisfying a relationship of 0.05≦

A/B≦

0.16 where A denotes a thickness of the polarizer and B denotes, a thickness of the protective film.

3. The polarizing plate according to claim 1, wherein thickness of the protective film is at least 80 μ

m.

4. The polarizing plate according to claim 3, wherein thickness of the protective film ranges 80 μ

m to 200 μ

m.

5. The polarizing plate according to claim 1, wherein the protective film is a triacetylcellulose film.

6. The polarizing plate according to claim 1, wherein the protective film and the polarizer are attached by an adhesive.

7. The polarizing plate according to claim 6, wherein the adhesive is a polyvinyl alcohol-based adhesive.

8. The polarizing plate according to claim 1, wherein an additional adhesive layer is formed on at least one surface of the polarizing plate.

9. The polarizing plate according to claim 1, wherein the polarizing plate has a dimensional change rate of not more than ±

0.7% in a longitudinal direction (MD) after being heated at 70°

C. for 120 hours.

10. The polarizing plate according to claim 1 further comprising, at least one optical layer selected from a reflector, a transreflector, a retardation plate, a lambda plate, a viewing angle compensating film, and a brightness-enhanced film.

11. The polarizing plate according to claim 10, wherein the polarizing plate and the optical layer are laminated through an adhesive layer.

12. The polarizing plate according to claim 10, wherein the optical layer is a reflector.

13. The polarizing plate according to claim 10, wherein the optical layer is a transreflector.

14. The polarizing plate according to claim 10, wherein the optical layer is a retardation plate.

15. The polarizing plate according to claim 10, wherein the optical layer is a lambda plate.

16. The polarizing plate according to claim 10, wherein the optical layer is a viewing angle compensating film.

17. The polarizing plate according to claim 10, wherein the optical layer is a brightness-enhanced film.

18. The polarizing plate according to claim 1, wherein, when the polarizer is heated at 80°

C. for 30 minutes, the shrinkage force in an absorption axis direction is at most 4.0 N/cm.

19. The polarizing plate according to claim 18, wherein, when the polarizer is heated at 80°

C. for 30 minutes, the shrinkage force in an absorption axis direction ranges 1.0 N/cm to 3.7 N/cm.

20. The polarizing plate according to claim 1, wherein the polarizer thickness is at most 25 μ

m.

21. The polarizing plate according to claim 1, wherein the polarizer thickness ranges from 10 μ

m to 18 μ

m.

22. The polarizing plate according to claim 1, wherein the hydrophilic polymer film before being stretched is a polyvinyl alcohol-based film.

23. The polarizing plate according to claim 22, wherein the polyvinyl alcohol-based film thickness is at most 60 μ

m.

24. The polarizing plate according to claim 22, wherein the polyvinyl alcohol has an average polymerization degree ranging from 500 to 10000, and an average saponification degree of at least 75 mol %.

25. The polarizing plate according to claim 1, wherein the polarizer is formed by dyeing, crosslinking, stretching and drying a hydrophilic polymer film.

26. The polarizing plate according to claim 1, wherein the polarizer is formed by a method comprising:

dyeing a hydrophilic polymer film before being stretched,

subjecting the film to a swelling treatment,

subjecting the film to a crosslinking treatment,

stretching the film and

drying the film,

wherein thickness of the hydrophilic polymer film before being stretched is at most 75 μ

m.

27. The polarizing plate according to claim 26, wherein the stretching of the film is conducted in water, and the crosslinking treatment is conducted with a crosslinking agent.

28. The polarizing plate according to claim 26, wherein the stretching of the film is conducted in a traverse direction, and subsequently in a longitudinal direction.

29. The polarizing plate according to claim 26, wherein the stretching of the film comprises stretching the film, relaxing stress of the film after stretching the film, and subsequently stretching the film.

30. A liquid crystal display comprising the polarizing plate according to claim 1 and a liquid crystal cell, wherein the polarizing plate is disposed on at least one surface of the liquid crystal cell.

31. The liquid crystal display according to claim 30, wherein the liquid crystal cell comprises at least one substrate selected from a glass substrate and a plastic substrate.