POLARIZING PLATE WITH AN OPTICAL COMPENSATION LAYER AND IMAGE DISPLAY APPARATUS USING THE SAME

• US 20090122236A1
• Filed: 10/11/2006
• Published: 05/14/2009
• Est. Priority Date: 10/21/2005
• Status: Abandoned Application

• Current Assignee: Nitto Denko Corporation
• Original Assignee: Nitto Denko Corporation
• Inventors: Kozonoi, Nobuyuki, Takahashi, Naoki, Osuka, Tatsuya, Toyama, Yusuke, Shutou, Shunsuke
• Application Number:
  US12/090,770
• Publication Number:
  US 20090122236A1
• Time in Patent Office: Days
• US Class Current: 349/96
• CPC Class Codes: G02B 5/305 including organic materials, e.g. polymeric layers
• CPC Class Codes: G02F 1/13363 Birefringent elements, e.g. for optical compensation
• CPC Class Codes: G02F 1/133634 the refractive index Nz perpendicular to the element surface being different from in-plane refractive indices Nx and Ny, e.g. biaxial or with normal optical axis
• CPC Class Codes: G02F 1/1393 the birefringence of the liquid crystal being electrically controlled, e.g. ECB-, DAP-, HAN-, PI-LC cells G02F1/1396, G02F1/141 take precedence
• CPC Class Codes: G02F 2202/28 Adhesive materials or arrangements
• CPC Class Codes: G02F 2413/03 Number of plates being 3
• CPC Class Codes: G02F 2413/07 All plates on one side of the LC cell
• CPC Class Codes: G02F 2413/08 with a particular optical axis orientation
• CPC Class Codes: G02F 2413/13 Positive birefingence

Abstract

There are provided a polarizing plate with an optical compensation layer capable of suppressing the degradation in optical properties due to the use under a high-temperature environment, and an image display apparatus using the polarizing plate with an optical compensation layer.

The polarizing plate with an optical compensation layer includes a polarizer, a pressure-sensitive adhesive layer and at least one optical compensation layer, in the stated order. The pressure-sensitive adhesive layer has a dynamic storage shear modulus (G′) at 100° C. of 1.0×10⁴ to 6.0×10⁴ Pa.

Claims

1. A polarizing plate with an optical compensation layer, comprising:

a polarizer;

a pressure-sensitive adhesive layer; and

at least one optical compensation layer, in the stated order,

wherein the pressure-sensitive adhesive layer has a dynamic storage shear modulus (G′

) at 100°

C. of 1.0×

10⁴ to 6.0×

10⁴ Pa.

2. A polarizing plate with an optical compensation layer according to claim 1, wherein:

the at least one optical compensation layer includes a first optical compensation layer, a second optical compensation layer, and a third optical compensation layer in the stated order;

the first optical compensation layer contains a resin having an absolute value of a photoelastic coefficient of 2×

10<sup>−

11</sup> m/N or less, a relationship of nx>

ny=nz, and an in-plane retardation Re₁ of 200 to 300 nm;

the second optical compensation layer contains a resin having an absolute value of a photoelastic coefficient of 2×

10<sup>−

11</sup> m²/N or less, a relationship of nx>

ny=nz, and an in-plane retardation Re₂ of 90 to 160 nm;

the third optical compensation layer has a relationship of nx=ny>

nz, an in-plane retardation Re₃ of 0 to 20 mm, and a thickness direction retardation Rth₃ of 30 to 300 nm; and

an angle formed by an absorption axis of the polarizer and a slow axis of the first optical compensation layer is 10 to 30°

, and an angle formed by the absorption axis of the polarizer and a slow axis of the second optical compensation layer is 70 to 90°

.

3. A polarizing plate with an optical compensation layer according to claim 2, wherein the pressure-sensitive adhesive layer is provided between the polarizer and the first optical compensation layer.

4. A polarizing plate with an optical compensation layer according to claim 2, wherein the third optical compensation layer has a thickness of 1 to 50 μ

m.

5. A polarizing plate with an optical compensation layer according to claim 2, wherein the third optical compensation layer is formed of a cholesteric alignment fixed layer having a selective reflection wavelength region of 350 nm or less.

6. A polarizing plate with an optical compensation layer according to claim 2, wherein the third optical compensation layer includes a layer formed of a film having a relationship of nx=ny>

nz and containing a resin having an absolute value of a photoelastic coefficient of 2×

10<sup>−

11</sup> m²/N or less, and a cholesteric alignment fixed layer having a selective reflection wavelength region of 350 nm or less.

7. A polarizing plate with an optical compensation layer according to claim 1, wherein the pressure-sensitive adhesive layer is formed of an acrylic pressure-sensitive adhesive.

8. A polarizing plate with an optical compensation layer according to claim 7, wherein:

the acrylic pressure-sensitive adhesive contains a (meth)acrylic polymer (A) obtained by copolymerizing 0.01 to 5 parts by weight of a hydroxyl group-containing (meth)acrylic monomer (a2) with respect to 100 parts by weight of alkyl(meth)acrylate (a1), a peroxide (B), and an isocyanate-based compound (C);

the peroxide (B) is blended in an amount of 0.02 to 2 parts by weight with respect to 100 parts by weight of the (meth)acrylic polymer (A); and

the isocyanate-based compound (C) is blended in an amount of 0.001 to 2 parts by weight with respect to 100 parts by weight of the (meth)acrylic polymer (A).

9. A liquid crystal panel, comprising:

the polarizing plate with an optical compensation layer according to claim 1; and

a liquid crystal cell.

10. A liquid crystal panel according to claim 9, wherein the liquid crystal cell is a reflection-type or a semi-transmission-type liquid crystal cell of a VA mode.

11. A liquid crystal display apparatus, comprising the liquid crystal panel according to claim 9.

12. An image display apparatus, comprising the polarizing plate with an optical compensation layer according to claim 1.