Polarizing plate

• US 6,726,995 B2
• Filed: 10/23/2002
• Issued: 04/27/2004
• Est. Priority Date: 12/28/1999
• Status: Expired due to Term

• Current Assignee: Gunze Limited, Poratechno Company Limited
• Original Assignee: Gunze Limited, Poratechno Company Limited
• Inventors: Uesugi, Takao, Yamamoto, Takeshi, Watanabe, Koichi, Ishii, Yoshinori
• Primary Examiner(s): Nakarani, D. S.
• Application Number:
  US10/149,447
• Publication Number:
  US 20030091792A1
• Time in Patent Office: 552 Days
• Field of Search: 428/424.2, 428/424.4, 428/424.8, 428/520, 428/521, 359/483
• US Class Current: 428/424.4
• CPC Class Codes: G02B 1/105 Protective coatings
• CPC Class Codes: G02B 1/14 Protective coatings, e.g. hard coatings
• CPC Class Codes: G02B 5/3033 in the form of a thin sheet or foil, e.g. Polaroid
• CPC Class Codes: Y10T 428/24364 with transparent or protective coating
• CPC Class Codes: Y10T 428/31573 Next to addition polymer of ethylenically unsaturated monomer
• CPC Class Codes: Y10T 428/31576 Ester monomer type [polyvinylacetate, etc.]
• CPC Class Codes: Y10T 428/31587 Hydrocarbon polymer [polyethylene, polybutadiene, etc.]
• CPC Class Codes: Y10T 428/31855 Of addition polymer from unsaturated monomers
• CPC Class Codes: Y10T 428/31928 Ester, halide or nitrile of addition polymer
• CPC Class Codes: Y10T 428/31931 Polyene monomer-containing

Abstract

A polarizing plate with which a drop in polarization efficiency, hue shift, and light leakage do not substantially arise, under a high humidity/high temperature environment is provided. The polarizing plate of the present invention comprises a polyvinyl-alcohol-based polarizing film, a protective film having thereon two anchor coat agent layers, mainly composed of a cyclic-olefin-based resin, laminated on at least one side of the polarizing film, with an adhesive. The amount of change in optical in-plane retardation of the protective film is 5 nm or less after 24 hours in an atmosphere of 80° C., and the wetting tension of the anchor coated surface of the protective film is 500 μN/cm (23° C.) or more. The anchor coat agent layers include a first layer made of polyisocyanate and polyester polyol and/or polyether polyol, and a second layer made of polyvinyl alcohol. The adhesive is made of polyvinyl alcohol.

Claims

1. A polarizing plate comprising a polarizing film made of polyvinyl-alcohol or a derivative thereof, a protective film mainly composed of a resin made of cyclic-olefin or a derivative thereof, the protective film having coated thereon two anchor coat agent layers, and the protective film being laminated on at least one side of the polarizing film with an adhesive:

wherein the amount of change in optical in-plane retardation of the protective film is 5 nm or less after 24 hours in an atmosphere of 80°

C., and the wetting tension of the surface to be anchor-coated of the protective film is 500 μ

N/cm (23°

C.) or more;

wherein the anchor coat agent layers include a first layer made of polyisocyanate and polyester polyol and/or polyether polyol, and a second layer made of polyvinyl alcohol; and

wherein the adhesive is made of polyvinyl alcohol.

2. The polarizing plate of claim 1, wherein the first layer is made of polyester polyol.

3. The polarizing plate of claim 1, wherein the first layer is made of polyether polyol.