Liquid-crystal display device

Abstract

Disclosed is a liquid-crystal display device comprising a polarizing plate comprising a polarizing element and a thermoplastic-resin film which comprises a lactone ring-having polymer and satisfies the following formulas (I) and (II): 0≦| Re (630)|≦10, and | Rth (630)|≦25  (I) | Re (400)− Re (700)|≦10, and | Rth (400)− Rth (700)|≦35  (II) wherein Re(λ) means retardation (nm) in plane at a wavelength λ nm; and Re(λ) means retardation (nm) along the thickness direction at a wavelength λ nm.

1 . A liquid-crystal display device comprising:
 a liquid-crystal cell which comprises:
 a pair of substrates disposed to face each other having an electrode on at least one of them, the electrode capable of forming an electric field containing a component running in parallel to the substrate, and 
 a liquid-crystal layer, of which alignment is controlled, disposed between the pair of substrates; and 
   a pair of polarizing plates disposed to sandwich the liquid-crystal cell therebetween,   wherein the thickness of the liquid-crystal layer is controlled by any of polymer beads, glass beads fibers and resinous columnar spacers, and the product of the thickness d (μm) of the liquid-crystal layer and the refractive anisotropy Δn thereof, Δn·d is from 0.2 to 1.2 μm,   wherein at least one of the pair of polarizing plates comprises a polarizing element and a thermoplastic-resin film which comprises a lactone ring-having polymer as a major ingredient and satisfies the following formulas (I) and (II),   
       wherein the lactone ring-having polymer has a repetitive structure unit to be constructed by polymerization of at least one selected from (meth)acrylates, hydroxyl group-containing monomers, unsaturated carboxylic acids and monomers of the following formula (2):
   −3 ≦Re (630)≦4, and −12 ≦Rth (630)≦6  (I)
 
   | Re (400)− Re (700)|≦10, and | Rth (400)− Rth (700)|≦35  (II)
 
 wherein Re(λ) means retardation (nm) in plane at a wavelength λ nm; and Rth(λ) means retardation (nm) along the thickness direction at a wavelength λ nm: 
 
       
         
           
           
               
               
           
         
       
       wherein R 4  represents a hydrogen atom or a methyl group; X represents a hydrogen atom, an alkyl group having from 1 to 20 carbon atoms, an aryl group, an acetate group, a cyano group, a group —CO—R 5  or a group —CO—O—R 6 , wherein R 5  and R 6  each represents a hydrogen atom or an organic residue having from 1 to 20 carbon atoms. 
     
     
         2 . The liquid-crystal display device of  claim 1 , wherein a polarizing plate disposed at the backlight side, at least, is said polarizing plate comprising the thermoplastic-resin film. 
     
     
         3 . The liquid-crystal display device of  claim 1 , wherein a polarizing plate disposed at the displaying plane side, at least, is said polarizing plate comprising the thermoplastic-resin film. 
     
     
         4 . The liquid-crystal display device of  claim 1 , wherein both of polarizing plates disposed at the backlight side and the displaying plane side are said polarizing plates comprising the thermoplastic-resin film. 
     
     
         5 . The liquid-crystal display device of  claim 1 , wherein Re{T} and Rth{T} (T means the temperature (° C.) at which the data is measured) of the thermoplastic-resin film at a wavelength of 550 nm satisfy the following formulas (III) and (IV):
   | Re{ 50 }−Re{ 25}|<5 nm,  (III)
 
   | Rth{ 50 }−Rth{ 25}|<10 nm.  (IV)
 
 
     
     
         6 . The liquid-crystal display device of  claim 5 , wherein Re{T} and Rth{T} (T means the temperature (° C.) at which the data is measured) of the thermoplastic-resin film at a wavelength of 550 nm satisfy the following formulas (III) and (IV):
   | Re{ 50 }−Re{ 25}|<5 nm,  (III)
 
   | Rth{ 50 }−Rth{ 25}|<10 nm.  (IV)
 
 
     
     
         7 . The liquid-crystal display device of  claim 1 , wherein Re[H] and Rth[H] (H means the relative humidity (%) at which the data is measured) of the thermoplastic-resin film at a wavelength of 550 nm satisfy the following formulas (V) and (VI):
   | Re[ 80 ]−Re[ 10]|<5 nm,  (V)
     | Rth[ 80 ]−Rth[ 10]|<10 nm.  (VI)
   
     
     
         8 . The liquid-crystal display device of  claim 7 , wherein Re[H] and Rth[H] (H means the relative humidity (%) at which the data is measured) of the thermoplastic-resin film at a wavelength of 550 nm satisfy. −3 nm≦Re[80]−Re[10]≦4 nm and −7 nm≦Re[80]−Re[10]≦9 nm. 
     
     
         9 . The liquid-crystal display device of  claim 1 , wherein the lactone ring-having polymer in the thermoplastic-resin film is from 50 to 100% by mass. 
     
     
         10 . The liquid-crystal display device of  claim 2 , wherein the lactone ring-having polymer in the thermoplastic-resin film is from 50 to 100 by mass. 
     
     
         11 . The liquid-crystal display device of  claim 3 , wherein the lactone ring-having polymer in the thermoplastic-resin film is from 50 to 100% by mass. 
     
     
         12 . The liquid-crystal display device of  claim 1 , wherein the lactone ring-having polymer has a weight-average molecular weight of from 1,000 to 2,000,000. 
     
     
         13 . The liquid-crystal display device of  claim 2 , wherein the lactone ring-having polymer has a weight-average molecular weight of from 1,000 to 2,000,000. 
     
     
         14 . The liquid-crystal display device of  claim 3 , wherein the lactone ring-having polymer has a weight-average molecular weight of from 1,000 to 2,000,000. 
     
     
         15 . The liquid-crystal display device of  claim 1 , wherein the lactone ring-having polymer has a lactone ring structure of the following formula (1): 
       
         
           
           
               
               
           
         
       
       wherein R 1 , R 2  and R 3  each independently represent a hydrogen atom, or an organic residue having from 1 to 20 carbon atoms, and the organic residue may contain an oxygen atom. 
     
     
         16 . The liquid-crystal display device of  claim 2 , wherein the lactone ring-having polymer has a lactone ring structure of the following formula (1): 
       
         
           
           
               
               
           
         
       
       wherein R 1 , R 2  and R 3  each independently represent a hydrogen atom, or an organic residue having from 1 to 20 carbon atoms, and the organic residue may contain an oxygen atom. 
     
     
         17 . The liquid-crystal display device of  claim 3 , wherein the lactone ring-having polymer has a lactone ring structure of the following formula (1): 
       
         
           
           
               
               
           
         
       
       wherein R 1 , R 2  and R 3  each independently represent a hydrogen atom, or an organic residue having from 1 to 20 carbon atoms, and the organic residue may contain an oxygen atom. 
     
     
         18 . The liquid-crystal display device of  claim 4 , wherein the lactone ring-having polymer has a lactone ring structure of the following formula (1): 
       
         
           
           
               
               
           
         
       
       wherein R 1 , R 2  and R 3  each independently represent a hydrogen atom, or an organic residue having from 1 to 20 carbon atoms, and the organic residue may contain an oxygen atom. 
     
     
         19 . The liquid-crystal display device of  claim 9 , wherein the lactone ring-having polymer has a lactone ring structure of the following formula (1): 
       
         
           
           
               
               
           
         
       
       wherein R 1 , R 2  and R 3  each independently represent a hydrogen atom, or an organic residue having from 1 to 20 carbon atoms, and the organic residue may contain an oxygen atom. 
     
     
         20 . The liquid-crystal display device of  claim 12 , wherein the lactone ring-having polymer has a lactone ring structure of the following formula (1): 
       
         
           
           
               
               
           
         
       
       wherein R 1 , R 2  and R 3  each independently represent a hydrogen atom, or an organic residue having from 1 to 20 carbon atoms, and the organic residue may contain an oxygen atom.