| 摘要 |
PURPOSE: To obtain an optical disk substrate having a high density recording capacity in which pits are accurately transferred without defects such as projections or recesses except for pits on the surface and less warpage is caused by moisture absorption. CONSTITUTION: This substrate is substantially consists of a polycarbonate resin in which at least 20mol% of the whole aromatic dihydroxy component is 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane. The polycarbonate resin shows such properties that the specific viscosity is 0.2-0.5 when 0.7g of the resin is dissolved in a 100ml methylene chloride and measured at 20 deg.C. The substrate is produced by injection-molding of the polycarbonate resin under conditions of 10-75 ton clamping force on the die, at 290-360 deg.C resin temp. and at 100-140 deg.C mold temp. |
