Optical Compensating Resin Film for Polarizing Plate, Method for Manufacturing Optical Compensating Resin Film, Polarizing Plate and Liquid Crystal Display Device

Abstract

Provided are an optical compensating resin film having improved contrast, a polarizing plate, which uses the optical compensating resin film and has excellent smoothness without color nonuniformity, and a liquid crystal display device. The optical compensating resin film is characterized in that the crystallinity degree is 0.15 or less.

1 - 9 . (canceled) 
     
     
         10 . An optical compensating resin film for a polarizing plate, comprising a resin,
 wherein the optical compensating resin film satisfies the following requirements:   Ro, defined by the following formula, is 20-300 nm at 23° C. and 55% relative humidity, or Rt, defined by the following formula, is 70-400 nm at 23° C. and 55 relative humidity,   the resin has a crystallinity degree of 0.15 or less,
     Ro =( nx−ny )× d    
     Rt =(( nx+ny )/2 −nz )× d,    
   wherein nx, ny, and nz each respectively represents a refractive index in a major axis x, y, and z direction of a refractive index ellipsoid, nx and ny each represents a refractive index in a in-plane direction of the resin film, nz represents a refractive index in a thickness direction, and d represents a film thickness (nm).   
     
     
         11 . The optical compensating resin film of  claim 10 , wherein the resin employed in the optical compensating resin film is a cellulose ester. 
     
     
         12 . The optical compensating resin film of  claim 11 , wherein the resin comprises the cellulose ester having an acyl group of 2-4 carbon atoms and the optical compensating resin film satisfies the following Formulas (I) and (II):
   2.1 <−X+Y<− 2.6  (I)     1.0 <X<− 2.6,  (II)   wherein X represents a substitution degree of an acetyl group, and Y represents a substitution degree of a propionyl group or a butyryl group.   
     
     
         13 . The optical compensating resin film of  claim 12 , wherein the resin comprises cellulose acetate propionate. 
     
     
         14 . The optical compensating resin film of  claim 13 , wherein cellulose acetate propionate satisfies the following Formulas (III) and (IV):
   1.0 X<− 2.0  (III)     0.5 Y<− 1.3  (IV)   wherein X and Y each respectively represents the same as designated for X and Y in Formulas (I) and (II).   
     
     
         15 . The optical compensating resin film of  claim 11 , further comprising at least one of plasticizers,
 wherein at least one of the plasticizers is an ester plasticizer having an aromatic group at a terminal of the molecule and represented by the following Formula (1):
   B-(G-A) n -G-B,  Formula (1) 
   wherein B represents a benzene monocarboxylic acid residual group; G represents an alkylene glycol residual group having 2-12 carbon atoms, an aryl glycol residual group having 6-12 carbon atoms, or an oxyalkylene glycol residual group having 4-12 carbon atoms; A represents an alkylene dicarboxylic acid residual group having 4-12 carbon atoms or an aryl dicarboxylic acid residual group having 6-12 carbon atoms; and n represents an integer of 1 or more.   
     
     
         16 . A method for manufacturing the optical compensating resin film of  claim 10 , comprising the steps of:
 applying a dope comprising a resin which exhibits a glass transition temperature of 170-185° C. determined via DSC by a solution casting to make a film;   peeling the film;   conveying the peeled film for at least 90 seconds in an ambience of at 55° C. or less; and   stretching the transferred film.   
     
     
         17 . A polarizing plate comprising the optical compensating resin film of  claim 10  at least on one side of the polarizing plate. 
     
     
         18 . A liquid crystal display device comprising a liquid crystal cell and the polarizing plate of  claim 17  at least on one side of the liquid crystal cell.