Reflective polarizing film, and optical member for liquid crystal display device, and liquid crystal display device formed from same

Patent metadata

Field	Value
Publication number	US-9405048-B2
Application number	US-201214122799-A
Country	US
Kind code	B2
Filing date	Jun 14, 2012
Priority date	Jun 17, 2011
Publication date	Aug 2, 2016
Grant date	Aug 2, 2016

Abstract

A multilayered reflective polarizing film is provided that has high polarization performance comparable to that of an absorption-type polarizing plate, and is preferred as a polarizing plate attached to a liquid crystal cell. An optical member for liquid crystal display devices, and a liquid crystal display device formed from such a multilayered reflective polarizing film are also provided. Specifically, the reflective polarizing film includes a uniaxially stretched multilayered film in which a specific aromatic polyester containing (alkylenedioxy)di-2-naphthoic acid as a part of dicarboxylic acid components is used as a first layer, and an optically isotropic polyester having an average refractive index of 1.50 to 1.60 is used as a second layer, and that has a predetermined refractive index difference between the layers. The reflective polarizing film has an angle of orientation of 2 degrees or less.

First claim

The invention claimed is:

1. A reflective polarizing film that comprises a uniaxially stretched multilayered film as a laminate of at least 251 alternately laminated first layers and second layers, wherein:
1) the first layers of the uniaxially stretched multilayered film are formed of a polyester containing dicarboxylic acid components and a diol component,
(i) the dicarboxylic acid components containing 5 mol % to 50 mol % of a component represented by the following formula (A), and 50 mol % to 95 mol % of a component represented by the following formula (B),

wherein R A represents an alkylene group of 2 to 4 carbon atoms,

wherein R B represents a naphthalenediyl group,
(ii) the diol component containing 90 mol % to 100 mol % of a component represented by the following formula (C),
H—O—R C —O—H  Formula C

wherein R C represents an alkylene group of 2 to 4 carbon atoms,
2) the second layers of the uniaxially stretched multilayered film are formed of an optically isotropic polyester having an average refractive index of 1.50 to 1.60,
3) the refractive index difference between the first layers and the second layers is 0.10 to 0.45 in a uniaxial stretch direction (X direction) within a film plane, and is 0.05 or less in a direction (Y direction) orthogonal to the uniaxial stretch direction, and in a film thickness direction (Z direction), and
4) the reflective polarizing film has an angle of orientation of 2 degrees or less, wherein said angle of orientation represents the tilt of the in-plane principal orientation axis with respect to the width direction of the film.

2. The reflective polarizing film according to claim 1 , comprising an outermost layer on at least one of the surfaces of the uniaxially stretched multilayered film,
wherein the retardation (Re) of the outermost layer as represented by the following formula (1) is 0 nm or more and less than 20 nm,
retardation( Re )=| nTD−nMD|× 1000 ×d   Formula 1

wherein nMD and nTD represent the refractive indices of the outermost layer in a machine direction and a width direction, respectively, and d represents the thickness (μm) of the outermost layer, and
wherein the outermost layer has a thickness of 2 μm to 10 μm.

3. The reflective polarizing film according to claim 2 , wherein the retardation (Rth) of the outermost layer in the thickness direction as represented by the following formula (2) is 0 nm or more and less than 50 nm,
retardation( Rth )=(( nMD+nTD )/2 −nZ )×1000 ×d   Formula 2

wherein nMD, nTD, and nZ represent the refractive indices of the outermost layer in the machine direction, the width direction, and the thickness direction, respectively, and d represents the thickness (μm) of the outermost layer.

4. A reflective polarizing plate for IPS mode liquid crystal displays, wherein the reflective polarizing plate is formed from the reflective polarizing film of claim 2 .

5. The reflective polarizing film according to claim 1 , comprising an outermost layer on at least one of the surfaces of the uniaxially stretched multilayered film,
wherein the retardation (Re) of the outermost layer as represented by the following formula (1) is 0 nm to 30 nm, and the retardation (Rth) of the outermost layer in the thickness direction as represented by the following formula (2) is 50 nm to 350 nm,
retardation( Re )=| nTD−nMD|× 1000 ×d   (1)

wherein nMD and nTD represent the refractive indices of the outermost layer in a machine direction and a width direction, respectively, and d represents the thickness (μm) of the outermost layer,
retardation( Rth )=(( nMD+nTD )/2 −nZ )×1000 ×d   (2)

(wherein nMD, nTD, and nZ represent the refractive indices of the outermost layer in the machine direction, the width direction, and the thickness direction, respectively, and d represents the thickness (μm) of the outermost layer), and
wherein the outermost layer has a thickness of 5 μm to 50 μm.

6. A reflective polarizing film for VA mode liquid crystal displays, wherein the reflective polarizing film is formed from the reflective polarizing film of claim 5 .

7. A reflective polarizing plate for VA mode liquid crystal displays, wherein the reflective polarizing plate is formed from the reflective polarizing film of claim 5 .

8. The reflective polarizing film according to claim 1 , wherein the average reflectance at 400 to 800 nm wavelengths for polarized light incident at 0 degree angle and reflected at the film surface of reflective polarizing film is 95% or more with regard to a polarized component parallel to an incident plane that includes the uniaxial stretch direction (X direction), and wherein the average reflectance at 400 to 800 nm wavelengths for the polarized light incident at 0 degree angle and reflected at the film surface of reflective polarizing film is 12% or less with regard to a polarized component perpendicular to the incident plane that includes the X direction.

9. The reflective polarizing film according to claim 1 , wherein the polyester forming the second layers is a polyester that contains copolymerized polyethylene terephthalate as a main component.

10. The reflective polarizing film according to claim 2 , wherein the outermost layer is formed of amorphous thermoplastic resin.

11. The reflective polarizing film according to claim 1 , wherein the polyester forming the second layers is a copolymerized polyester having a glass transition point of 80° C. or more.

12. The reflective polarizing film according to claim 11 , wherein the reflective polarizing film has a rate of thermal shrinkage of 1.5% or less under 85° C., 30 minute conditions.

13. The reflective polarizing film according to claim 11 , wherein the copolymerized polyester forming the second layer is a copolymerized polyethylene terephthalate that contains alicyclic diol as a copolymer component.

14. The reflective polarizing film according to claim 13 , wherein the copolymer component forming the copolymerized polyethylene terephthalate is at least one selected from the group consisting of spiroglycol, tricyclodecane dimethanol, and cyclohexane dimethanol.

15. The reflective polarizing film according to claim 11 , wherein the copolymerized polyester forming the second layers is a copolymerized polyethylene naphthalate that contains at least one of alicyclic dicarboxylic acid and alicyclic diol as a copolymer component.

16. The reflective polarizing film according to claim 15 , wherein the copolymer component forming the copolymerized polyethylene naphthalate is at least one selected from the group consisting of cyclohexane dicarboxylic acid, decahydronaphthalene dicarboxylic acid, spiroglycol, tricyclodecane dimethanol, and cyclohexane dimethanol.

17. An optical member for liquid crystal display devices, the optical member comprising a first polarizing plate formed from the reflective polarizing film of claim 1 , a liquid crystal cell, and a second polarizing plate, wherein the first polarizing plate, the liquid crystal cell, and the second polarizing plate are laminated in this order.

18. The optical member for liquid crystal display devices according to claim 17 , wherein the second polarizing plate is formed from a reflective polarizing film that comprises a uniaxially stretched multilayered film as a laminate of at least 251 alternately laminated first layers and secon

Assignees

• Oya Taro
• Ono Mitsumasa
• Yoshida Tetsuo
• Teijin Ltd

Inventors

• Oya Taro
• Ono Mitsumasa
• Yoshida Tetsuo

Classifications

• G02B5/3025 Primary

  Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state (G02B5/3008, G02B5/3016 take precedence) · CPC title

• Y10T428/10

  Cross-Sectional Technologies · mapped topic

• G02B5/305

  including organic materials, e.g. polymeric layers · CPC title

• G02F2001/133545

  Physics · mapped topic

• Y10T428/1036

  Cross-Sectional Technologies · mapped topic