Polarizing plate and liquid crystal display comprising the same

Patent metadata

Field	Value
Publication number	US-2016062012-A1
Application number	US-201514842727-A
Country	US
Kind code	A1
Filing date	Sep 1, 2015
Priority date	Sep 3, 2014
Publication date	Mar 3, 2016
Grant date	—

Abstract

A polarizing plate includes a polarizer, and a polyester film formed on one or both surfaces of the polarizer. The polyester film has a tensile strength ratio of about 3 or greater, as calculated by Equation 4, and an orientation displacement (°) of about −5° to about +5° with respect to a transverse direction (slow axis) of the polyester film at a wavelength of 550 nm. A liquid crystal display apparatus includes the polarizing plate.
Tensile strength ratio=TD tensile strength/MD tensile strength.  Equation 4

First claim

What is claimed is:

1 . A polarizing plate, comprising:
a polarizer; and a polyester film on a surface of the polarizer, wherein the polyester film has a tensile strength ratio of about 3 or greater, as calculated by Equation 4, and an orientation displacement (°) of about −5° to about +5° with respect to a transverse direction of the polyester film at a wavelength of 550 nm:
Tensile strength ratio=TD tensile strength/MD tensile strength.  Equation 4

2 . The polarizing plate according to claim 1 , wherein the polyester film has a TD tensile strength of about 200 MPa to about 400 MPa, and an MD tensile strength of about 60 MPa to about 120 MPa.

3 . The polarizing plate according to claim 1 , wherein the polarizing plate has an angle (θr−p) between an absorption axis (θp) of the polarizer and an optical axis (θr) of the polyester film of about −0.3° to about +0.3°.

4 . The polarizing plate according to claim 1 , wherein the polyester film has a front retardation (Ro) at a wavelength of 550 nm of about 5,000 nm to about 15,000 nm.

5 . The polarizing plate according to claim 1 , wherein the polyester film has a degree of biaxiality (NZ) at a wavelength of 550 nm of about 1.8 or lower, as calculated by Equation 1.
NZ =( nx−nz )/( nx−ny ),  Equation 1
wherein nx, ny and nz are indices of refraction at a wavelength of 550 nm in x-, y- and z-axis directions of the polyester film, respectively.

6 . The polarizing plate according to claim 1 , wherein the polyester film comprises at least one of polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, and/or polybutylene naphthalate.

7 . The polarizing plate according to claim 1 , further comprising:
at least one of an optical film, a coating layer and/or an adhesive layer formed on an other surface of the polarizer.

8 . The polarizing plate according to claim 7 , wherein the optical film has a front retardation (Ro) at a wavelength of 550 nm of about 40 to about 60 nm.

9 . The polarizing plate according to claim 7 , wherein the optical film comprises at least one of a cellulose resin, a polyester resin, a cyclic polyolefin resin, a polycarbonate resin, a polyethersulfone resin, a polysulfone resin, a polyamide resin, a polyimide resin, a polyolefin resin, a polyarylate resin, a polyvinyl alcohol resin, a polyvinyl chloride resin, and/or a polyvinylidene chloride resin.

10 . The polarizing plate according to claim 1 , wherein the polarizing plate has a variation rate of a polarization degree of about 0.00 to about 0.05%, as calculated by Equation 3:
Variation rate of polarization degree=| P 2− P 1|/ P 1×100  Equation 3
wherein P1 is an initial degree of polarization of the polarizing plate, and P2 is a degree of polarization of the polarizing plate after being left at about 85° C. for about 500 hours.

11 . A liquid crystal display comprising the polarizing plate according to claim 1 .

12 . The liquid crystal display according to claim 11 , wherein the polyester film has a TD tensile strength of about 200 MPa to about 400 MPa, and an MD tensile strength of about 60 MPa to about 120 MPa.

13 . The liquid crystal display according to claim 11 , wherein the polarizing plate has an angle (θr−p) between an absorption axis (θp) of the polarizer and an optical axis (θr) of the polyester film of about −0.3° to about +0.3°.

14 . The liquid crystal display according to claim 11 , wherein the polyester film has a front retardation (Ro) at a wavelength of 550 nm of about 5,000 nm to about 15,000 nm.

15 . The liquid crystal display according to claim 11 , wherein the polyester film has a degree of biaxiality (NZ) at a wavelength of 550 nm of about 1.8 or lower, as calculated by Equation 1.
NZ =( nx−nz )/( nx−ny ),  Equation 1
wherein nx, ny and nz are indices of refraction at a wavelength of 550 nm in x-, y- and z-axis directions of the polyester film, respectively.

16 . The liquid crystal display according to claim 11 , wherein the polyester film comprises at least one of polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, and/or polybutylene naphthalate.

17 . The liquid crystal display according to claim 11 , wherein the polarizing plate further comprises:
at least one of an optical film, a coating layer and/or an adhesive layer formed on an other surface of the polarizer.

18 . The liquid crystal display according to claim 17 , wherein the optical film has a front retardation (Ro) at a wavelength of 550 nm of about 40 to about 60 nm.

19 . The liquid crystal display according to claim 17 , wherein the optical film comprises at least one of a cellulose resin, a polyester resin, a cyclic polyolefin resin, a polycarbonate resin, a polyethersulfone resin, a polysulfone resin, a polyamide resin, a polyimide resin, a polyolefin resin, a polyarylate resin, a polyvinyl alcohol resin, a polyvinyl chloride resin, and/or a polyvinylidene chloride resin.

20 . The liquid crystal display according to claim 11 , wherein the polarizing plate has a variation rate of a polarization degree of about 0.00 to about 0.05%, as calculated by Equation 3:
Variation rate of polarization degree=| P 2− P 1|/ P 1×100  Equation 3
wherein P1 is an initial degree of polarization of the polarizing plate, and P2 is a degree of polarization of the polarizing plate after being left at about 85° C. for about 500 hours.

Assignees

• Samsung Sdi Co Ltd

Inventors

• Shin Kwang Ho
• Park Eun Su
• Shin Dong Yoon
• Chung Hae Ryong

Classifications

• G02F1/133528

  Polarisers · CPC title

• G02B5/305 Primary

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

• G02B1/14

  Protective coatings, e.g. hard coatings · CPC title

• G02B5/3083

  Birefringent or phase retarding elements (G02B5/3008, G02B5/3016 take precedence; systems for polarisation control G02B27/286; manufacturing phase modulating patterns by lithographic processes G03F7/001) · CPC title

• G02F1/133634

  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 title