Process of producing a polarizer, polarizer, polarizing plate, and visual display

• US 6,760,156 B2
• Filed: 09/19/2002
• Issued: 07/06/2004
• Est. Priority Date: 09/20/2001
• Status: Active Grant

• Current Assignee: Nitto Denko Corporation
• Original Assignee: Nitto Denko Corporation
• Inventors: Tsuchimoto, Kazuki, Nishida, Akihiro, Kondo, Seiji
• Primary Examiner(s): Chang, Audrey
• Assistant Examiner(s): Curtis, Craig
• Application Number:
  US10/246,543
• Publication Number:
  US 20030067683A1
• Time in Patent Office: 656 Days
• Field of Search: 359/483, 359/485, 359/492, 359/494, 359/500, 264/131
• US Class Current: 359/487.06
• CPC Class Codes: B29C 55/026 of preformed plates or sheets coated with a solution, a dispersion or a melt of thermoplastic material
• CPC Class Codes: B29D 11/00 Producing optical elements, e.g. lenses or prisms grinding or polishing of optical elements B24B; constructional form of optical elements G02B; optical parts of spectacles G02C7/00
• CPC Class Codes: B29K 2029/04 PVOH, i.e. polyvinyl alcohol B29K2031/04 takes precedence
• CPC Class Codes: B29K 2995/0034 Polarising
• CPC Class Codes: G02B 5/3033 in the form of a thin sheet or foil, e.g. Polaroid

Abstract

A polarizer provide that has a high polarization degree and a high transmittance, which is made of a polyvinyl alcohol film, may be produced by a process of producing, comprising the steps of: subjecting a non-stretched polyvinyl alcohol film to uniaxial dry stretching treatment to give a stretch ratio of 4 times or less, dyeing the film, and then subjecting the film to uniaxial stretching treatment to give a stretch ratio of less than 1.5 times under the condition containing a boron compound.

Claims

1. A process of producing a polarizer, comprising the steps of:

subjecting a non-stretched polyvinyl alcohol film to uniaxial dry stretching treatment to give a stretch ratio of 4 times or less,

dyeing the film,

and then subjecting the film to uniaxial stretching treatment to give a stretch ratio of less than 1.5 times in the course of a treatment with a boron compound.

2. The process according to claim 1, wherein a shape ratio (dimension in a stretching direction/dimension in a direction transverse to the stretching direction) of the film to be subjected to the uniaxial stretching treatment, which is performed in the course of a treatment with the boron compound, is set to 1.2 or more.

3. The process according to claim 1, wherein the transmittance of the polarizer is 43% or more, and the polarization degree thereof is 96% or more.

4. A polarizer obtained by the process according to claim 1.

5. A polarizing plate with an optical transparent protective layer on at least one side of the polarizer according to claim 4.

6. The polarizing plate according to claim 5, comprising a retardation plate.

7. The polarizing plate according to claim 5, comprising a viewing angle compensation film.

8. The polarizing plate according to claim 5, comprising a reflective plate.

9. The polarizing plate according to claim 5, comprising a transflective plate.

10. The polarizing plate according to claim 5, comprising a brightness enhancement film.

11. A visual display using the polarizing plate according to any one of claims 5-6 and 7-10.

12. The process according to claim 1, wherein the stretch ratio in the course of a treatment with a boron compound is 1.45 times or less.

13. The process according to claim 1, wherein a total stretch ratio is from 4.5 to less than 6 times.

14. The process according to claim 1, wherein the stretch ratio in the course of a treatment with a boron compound is 1.4 times or less.