| 摘要 |
PURPOSE:To obtain an optical information recording medium which satisfies the standard of block error rate specified by the compact disk (CD) standard and has excellent weather resistance by specifying the pencil hardness, coefft. of thermal expansion and shrinkage rate of a protective layer. CONSTITUTION:The optical information recording medium 1 is provided with light-transmitting substrate 2, light-absorbing layer 3 formed on the substrate 2, light-reflecting layer 4 formed on the light-absorbing layer 3, and a protective layer 5 formed on the light-reflecting layer 4. In this case, the protective layer 5 is formed so that it shows 2H or harder pencil hardness, the coefft. of thermal expansion alpha of 1.5 X 10<-5> <= alpha <= 9.0 X 10<-5> (1/ deg.C) at the user environment temp. range of -15 deg.C to 70 deg.C, and <=12% shrinkage when hardened. The protec tive layer 5 and the substrate 2 are joined at the circumference edge to improve the whole strength of the optical information recording medium and to protect inner light-absorbing layer 3 and light-reflecting layer 4. By this method, repro duction signals which satisfy the CD standard can be obtained and the obtd. protective layer satisfies the requirements for an optical information recording medium. |
