| 摘要 |
PURPOSE:To improve heat resistance and adhesion property to a surface recording layer and to reduce water absorption by using hydrocarbon resin with specified softening point for the substrate, treating the surface of the substrate with fluorine-contg. gas and specifying the contact angle of the surface with water after treatment and further specifying the weight increase of the substrate. CONSTITUTION:The optical disk substrate consists of a hydrocarbon resin having >=100 deg.C softening point. The surface of the substrate is treated with fluorine- contg. gas and the contact angle of the surface after treatment with water is specified to <=90 deg.C. Moreover, the surface is treated so that the weight increase is <=1wt.%. As for the resin having >=100 deg.C softening point, polyvinyl cyclohexane resin is used, in which styrene resin is subjected to nuclear hydrogenation. The nuclear hydrogenation is effected under 50 - 250kg/cm<2> pressure at 100 - 200 deg.C with a saturated hydrocarbon solvent such as cyclohexane. As for the fluorine-contg. gas, a mixture gas of F2 gas and O2 gas diluted with inert gas such as N2 and Ar is used. |
