Anti-Reflection Film, Manufacturing Method Thereof, Polarizing Plate and Transmission Type LCD

Abstract

The present invention provides an anti-reflection film which has excellent optical properties at a low production cost. The anti-reflection film of the present invention has a low refractive index hard coat layer having low refractive index particles and a binder matrix which is formed by curing an ionizing radiation curable material on a transparent substrate. It is a feature of the anti-reflection film of the present invention that the low refractive index hard coat layer has two optically distinguishable layers from the transparent substrate side, namely, an intermediate layer and a localized layer wherein the low refractive index particles are localized, and the refractive index and optical thickness of the localized layer are in the range of 1.29-1.43 and in the range of 100-200 nm, respectively.

1 . An anti-reflection film comprising:
 a transparent substrate; and   a low refractive index hard coat layer, said low refractive index hard coat layer comprising low refractive index particles and a binder matrix which is formed by curing an ionizing radiation curable material, said low refractive index hard coat layer comprising a mixed layer in which said binder matrix and a component of said transparent substrate blend together with a gradient and a localized layer which comprises said low refractive index particles and said binder matrix, said mixed layer being optically indistinguishable, and said localized layer being optically distinguishable and having a refractive index in the range of 1.29-1.43 and an optical thickness in the range of 100-200 nm.   
     
     
         2 . The anti-reflection film according to  claim 1 , wherein said localized layer has an optical thickness in the range of 110-140 nm. 
     
     
         3 . The anti-reflection film according to  claim 1 , wherein a content ratio of said low refractive index particles in said low refractive index hard coat layer is in the range of 0.5-5 wt %, and a content amount of said low refractive index particles per unit area of said low refractive index hard coat layer is in the range of 0.05-0.5 g/m 2 . 
     
     
         4 . The anti-reflection film according to  claim 1 , further comprising:
 an intermediate layer which is optically indistinguishable and arranged between said mixed layer and said localized layer, and comprises said binder matrix and said component of said transparent substrate.   
     
     
         5 . The anti-reflection film according to  claim 4 , wherein said intermediate layer includes 95 wt % or more of said binder matrix. 
     
     
         6 . The anti-reflection film according to  claim 1 , wherein said mixed layer has a thickness of 0.5 μm or more. 
     
     
         7 . The anti-reflection film according to  claim 1 , wherein an average luminous reflectance on said localized layer side surface of said anti-reflection film is in the range of 0.5-2.0%, and a reflection hue in the L*a*b* chromaticity coordinate system on said localized layer side surface of said anti-reflection film satisfies 0.00≦a*≦3.00 and −3.00≦b*≦3.00. 
     
     
         8 . The anti-reflection film according to  claim 1 , wherein said low refractive index hard coat layer further comprises an electron conducting polymer. 
     
     
         9 . The anti-reflection film according to  claim 1 , wherein said transparent substrate comprises triacetyl cellulose film. 
     
     
         10 . A polarizing plate comprising:
 said anti-reflection film according to  claim 1 ;   a polarizing layer; and   a second transparent substrate, said polarizing layer and said second transparent substrate being arranged on the opposite surface of said anti-reflection film from a side on which said low refractive index hard coat layer is formed.   
     
     
         11 . A transmission type LCD comprising:
 said polarizing plate according to  claim 10 ;   a liquid crystal cell;   a second polarizing plate; and   a backlight unit.   
     
     
         12 . A method for manufacturing an anti-reflection film which has a low refractive index hard coat layer on a transparent substrate comprising:
 preparing a coating liquid for forming said low refractive index hard coat layer comprising low refractive index particles, a binder matrix which includes an ionizing radiation curable material, and solvents;   coating said coating liquid for forming said low refractive index hard coat layer to form a coated layer on said transparent substrate;   drying said coated layer; and   irradiating ionizing radiation to said coated layer to form said low refractive index hard coat layer, said solvents in said coating liquid for forming said low refractive index hard coat layer including a solvent which dissolves said transparent substrate or causes said transparent substrate to swell by a ratio in the range of 30-90 wt %, said low refractive index hard coat layer including a mixed layer in which said binder matrix and a component of said transparent substrate blend together with a gradient and a localized layer which comprises said low refractive index particles and said binder matrix, said mixed layer being optically indistinguishable, and said localized layer being optically distinguishable and having a refractive index in the range of 1.29-1.43 and an optical thickness in the range of 100-200 nm.   
     
     
         13 . The method according to  claim 12 , wherein it takes a period of time in the range of 2-60 seconds for said solvents contained in said coated layer to evaporate off to a level of 10 wt % or lower after said coated layer is formed. 
     
     
         14 . The method according to  claim 12 , wherein said coating liquid for forming said low refractive index hard coat layer contains said solvents by a ratio in the range of 55-85 wt %. 
     
     
         15 . The method according to  claim 12 , wherein the process of drying said coated layer is performed under an atmosphere condition of a solvent concentration in the range of 0.2-10 vol %. 
     
     
         16 . The method according to  claim 12 , wherein said process of drying said coated layer includes a primary drying process which is preformed at a temperature in the range of 20-30° C. just after said coated layer is formed and a secondary drying process which is performed at a temperature in the range of 50-150° C. after said primary drying. 
     
     
         17 . The method according to  claim 16 , wherein it takes a period of time in the range of 2-60 seconds to perform said primary drying process. 
     
     
         18 . The method according to  claim 12 , wherein said transparent substrate comprises triacetyl cellulose and said solvents in said coating liquid for forming said low refractive index hard coat layer includes N-methylpyrrolidone.