| 摘要 |
PURPOSE:To obtain an optical disk having small retardation characteristic and superior optical uniformness nd high sensitivity for reading information recorded in the disk by using polysulfone resin having 2,000-200,000 number average mol.wt. and consisting of specified recurrent groups. CONSTITUTION:A polysulfone resin having 2,000-200,000 number average mol.wt. and consisting of recurrent groups expressed by the formula I is used as the base material. In the formula, R1 is H or phenyl group; R2 is H, methyl, phenyl, or biphenyl group. If the number average mol.wt. is <2,000, the optical disk is warped or twisted, etc. easily by the change of heat. If the number average mol.wt. is >200,000, the disk will become hardly moldable. By this constitution, an optical disk causing hardly retardation, having superior optical uniformness and high sensitivity for reading of information recorded in the disk is obtd. |
