Hard coat film, production method of the same, polarizing plate and display

Abstract

To provide hard coat films having high hardness, and uniform durability against scratching and high flatness even with a small thickness and a large width, and to provide a method producing the same. The hard coat films are provided with an actinic ray curable resin on a cellulose ester film thereof, the cellulose ester film containing a UV absorber and 2 or more plasticizers. One of the plasticizers is a polyalcohol ester type and the other one is a non-phosphate ester type. The cellulose ester film is produced by biaxially stretching of a cellulose ester film with a total acyl substitution degree ranging from 2.6 to 2.9, a number-average molecular weight ranging from 80,000 to 200,000, and a ratio of a weight-average molecular weight to a number-average molecular weight ranging from 1.4 to 3.0.

1 . A hard coat film comprising a cellulose ester film containing a UV absorbing agent and two or more plasticizers, the cellulose ester film having thereon a layer of an actinic ray-cured resin, 
 wherein:    (i) the plasticizers includes a polyalcohol ester and a non-phosphate ester;    (ii) the cellulose ester has a total acyl substitution degree of from 2.6 to 2.9;    (iii) the cellulose ester has a number average molecular weight (Mn) from 80,000 to 200,000;    (iv) the cellulose ester has a Mw/Mn ratio from 1.4 to 3.0, Mw representing a weight average molecular weight;    (v) the cellulose ester film is a stretched film; and    (vi) the actinic ray-cured resin layer is prepared by coating an actinic ray-curable resin on the cellulose ester film followed by hardening the actinic ray-curable resin via irradiation.    
   
   
       2 . The hard coat film of  claim 1 , wherein the amount of a phosphate ester type plasticizer included in the cellulose ester film is less than 1% by weight.  
   
   
       3 . The hard coat film of  claim 2 , wherein the amount of a phosphate ester type plasticizer included in the cellulose ester film is less than 0.1% by weight.  
   
   
       4 . The hard coat film of  claim 1 , wherein the cellulose ester film is biaxially stretched film.  
   
   
       5 . The hard coat film of  claim 1 , wherein the cellulose ester film has a thickness of from 10 to 70 μm.  
   
   
       6 . The hard coat film of  claim 1 , wherein the cellulose ester film has a d/H value of from 4 to 10, d representing a thickness of the cellulose ester film and H representing a thickness of the layer of the actinic ray-cured resin.  
   
   
       7 . The hard coat film of  claim 1 , wherein the hard coat film has a width of from 1.4 to 4.0 μm.  
   
   
       8 . The hard coat film of  claim 1 , wherein the actinic ray-cured resin layer has a thickness of from 0.1 to 10 μm.  
   
   
       9 . The hard coat film of  claim 8 , wherein the actinic ray-cured resin layer has a thickness of from 1.0 to 10 μm.  
   
   
       10 . The hard coat film of  claim 1 , wherein a retardation in plane Ro of the cellulose ester film is from 0 to 70 nm and a retardation in the thickness direction Rt is not more than 400 nm, Ro and Rt being represented by the following formulae,  
         Ro =( nx−ny )× d      Rt =(( nx+ny )/2 −nz )× d    where d is thickness (nm) of the cellulose ester film, nx is a refractive index in a delayed phase axis direction of the cellulose ester film, ny is a refractive index in plane of the cellulose ester film in the direction of normal to the delayed phase axis direction of the cellulose ester film and nx is a refractive index in the thickness direction of the cellulose ester film.    
   
   
       11 . The hard coat film of  claim 1 , wherein a visible-light transmittance of the cellulose ester film is not less than 90%.  
   
   
       12 . The hard coat film of  claim 1 , wherein a haze of the cellulose ester film is less than 1%.  
   
   
       13 . An antireflective film comprising the hard coat film of  claim 1  and an antireflective layer on the actinic ray-cured resin layer.  
   
   
       14 . A polarizing plate comprising: 
 the hard coat film of  claim 1;     an antireflective layer on one surface thereon the actinic ray-cured resin layer are provided;    a polarizing film provided on the other surface of the hard coat film; and    a cellulose ester retardation film on the polarizing film.    
   
   
       15 . The polarizing plate of  claim 14 , wherein a retardation in plane Ro of the cellulose ester retardation film is from 20 to 70 nm and a retardation in the thickness direction Rt is from 100 nm to 400 nm, Ro and Rt being represented by the following formulae,  
         Ro =( nx−ny )× d      Rt =(( nx+ny )/2 −nz )× d    where d is thickness (nm) of the cellulose ester retardation film, nx is a refractive index in a delayed phase axis direction of the cellulose ester film, ny is a refractive index in plane of the cellulose ester retardation film in the direction of normal to the delayed phase axis direction of the cellulose ester retardation film and nx is a refractive index in the thickness direction of the cellulose ester retardation film.    
   
   
       16 . A liquid crystal display comprising a liquid crystal display member including the hard coat film of  claim 1  on a surface of the liquid crystal display member.  
   
   
       17 . A liquid crystal display comprising a liquid crystal display member including the polarizing plate of  claim 16 .  
   
   
       18 . A method of producing a hard coat film comprising the steps of: 
 i) flow-casting a solution containing a cellulose ester, a UV absorbing agent, two or more plasticizers and a solvent on a support so as to form a cellulose ester film, wherein: 
 (a) the plasticizer includes a polyalcohol ester and a non-phosphate ester;  
 (b) the cellulose ester has a total acyl substitution degree from 2.6 to 2.9;  
 (c) the cellulose ester has a number average molecular weight (Mn) from 80,000 to 200,000; and  
 (d) the cellulose ester has a Mw/Mn ratio from 1.4 to 3.0, Mw representing a weight average molecular weight;  
   (ii) drying the cellulose ester film to a state in which the cellulose ester film is capable of being peeled from the support;    (iii) peeling the cellulose ester film from the support;    (iv) stretching the cellulose ester film while the cellulose ester film still contains the solvent;    (v) drying the cellulose ester film;    (vi) coating an actinic ray-curable resin o the cellulose ester film; and    (vii) hardening the actinic ray-curable resin by irradiating with an actinic ray.    
   
   
       19 . The method of  claim 19 , wherein a quantity of light for irradiation in the hardening step is from 5 to 100 mJ/cm 2 .  
   
   
       20 . The method of  claim 19 , wherein the cellulose ester film is biaxially stretched in the stretching step.  
   
   
       21 . The method of  claim 21 , wherein in the stretching step, the cellulose ester film is stretched in a longitudinal direction, and then is stretched in a lateral direction using a tenter, while the film still contains the solvent.  
   
   
       22 . The method of  claim 19 , wherein in the hardening step, the actinic ray-curable resin is hardened while the film is stretched.