| 摘要 |
PURPOSE:To enhance heat resistance, reduce optical distorsion and prolong useful life, by forming a substrate of an optical disk from a resin comprising a specified polysulfone resin. CONSTITUTION:The substrate of an optical disk is formed from a resin comprising a polysulfone resin shown by formula I or II, wherein each of U and V is H or a 1-6C aliphatic hydrocarbon group, the group -X-Y-Z- is a shown by formula III or IV, and the group -X'-Y'-Z'- is the group -X-Y-Z- or a group shown by formula V. The resin comprising the polysulfone resin is preferably injection molded at a cylinder temperature of at least 370 deg.C and a mold temperature of at least 120 deg.C. When the optical disk is produced by injection molding using the polysulfone resin, stress relaxation occurs during a cooling process because of a low photoelasticity constant of the resin, notwithstanding the high viscosity of the molten resin, resulting in that the optical distorsion, i.e., birefringence property of the disk substrate obtained is low. |
