| 摘要 |
PROBLEM TO BE SOLVED: To suppress white dots produced in a substrate to the min. by preparing the substrate from a polycarbonate resin having a specified or smaller number of substances of a specified or larger size per kg which emit light by irradiation of light at a specified wavelength and having a specified range of viscosity average mol.wt. SOLUTION: This polycarbonate resin has <=100 particles/kg, preferably <=80 particles/kg content of substances having >=30 μm size which emit light by irradiation of light at 380 nm wavelength. The mol.wt. of the polycarbonate resin prepared by the reaction of divalent phenols and a carbonate precursor in a melt-polymn. condensation method is 10000 to 22000. In the process to produce the polycarbonate resin in pellets, foreign matters are removed by passing the resin through a sintered metal filter or the like. The cylinder temp. during injection molding is 300 to 400 deg.C, and the die temp. is preferably 50 to 140 deg.C. The number of white dots having >=20 μm size produced in an accelerated deterioration test is <=2 per disk type substrate having 120 mm diameter. |
