Optical recording medium and production method therefor

Abstract

An optical recording medium capable of suppressing warps arising during a long time use and a method of producing the same, which has the configuration of comprising a substrate 13, an optical recording layer 14 formed on the substrate 13 and a light transmitting protective film 17 formed on the optical recording layer 14, wherein the protective film 17 includes a polymer film 16 having a thermal shrinkage coefficient of 0.02% or less and an adhesive layer 15 for adhering the polymer film 16 to the optical recording layer 14. As the polymer film 16, those produced by a melt cast method, subjected to annealing processing in advance or having a residual solvent of 0.3% by weight or less in the film may be preferably used.

1 . An optical recording medium, comprising: 
 a substrate;    an optical recording medium formed on said substrate; and    a light transmitting protective film formed on said optical recording layer;    wherein 
 said protective film comprises a polymer film having a thermal shrinkage coefficient of 0.02% or less and an adhesive layer for adhering said polymer film to said optical recording layer.  
   
     
     
         2 . An optical recording medium as set forth in  claim 1 , wherein said polymer film is a polymer film produced by a melt cast method.  
     
     
         3 . An optical recording medium as set forth in  claim 1 , wherein said polymer film is a polymer film subjected to annealing processing after being produced as a film and before being adhered to said optical recording layer in advance.  
     
     
         4 . An optical recording medium as set forth in  claim 1 , wherein a residual solvent in said polymer film is 0.3% by weight or less.  
     
     
         5 . A method of producing an optical recording medium, including the steps of: 
 forming an optical recording layer on a substrate; and    forming a light transmitting protective film on said optical recording layer;    wherein 
 the step of forming said protective film includes a step of adhering a polymer film having a thermal shrinkage coefficient of 0.02% or less to said optical recording layer via an adhesive layer.  
   
     
     
         6 . A method of producing an optical recording medium as set forth in  claim 5 , wherein a polymer film produced by a melt cast method is used as said polymer film.  
     
     
         7 . A method of producing an optical recording medium as set forth in  claim 5 , wherein annealing processing is performed on said polymer film after the step of producing the polymer film as a film and before the step of adhering to said optical recording layer in advance.  
     
     
         8 . A method of producing an optical recording medium as set forth in  claim 5 , wherein a polymer film wherein a residual solvent in the polymer film is 0.3% by weight or less is used as said polymer film.