| 摘要 |
PROBLEM TO BE SOLVED: To obtain an optical disk which is strong to a rapid environmental change without increasing the manufacturing cost. SOLUTION: A protective layer 4 is so constituted that the numerical value obtd. by multiplying its Young's modulus, film thickness, water absorptivity and water vapor permeation rate attains >=15kg/m<3> .24h (where the numerical value obtd. by multiplying the Young's modulus and the film thickness is <=3.0kg/mm) and that the curing shrinkage rate thereof attains <=12% in the case where a polycarbonate resin having 1.2mm thickness is used as a light- transmissible substrate 2. The change rate in the warpage angle of the optical disk is made small by constituting the optical disk in such a manner and, therefore, the optical disk suitable for a high density is obtd. |
