| 摘要 |
PROBLEM TO BE SOLVED: To obtain the subject material capable of shortening the measuring time in molding and a molding cycle besides mold release properties and producing an optical disc substrate having reduced silver streaks in good productivity, by externally adding a specific mold release agent to polycarbonate pellets. SOLUTION: This molding material is obtained by externally mixing (A) pellets (e.g. the ones having 2.5-3.5 mm average length) of a polycarbonate (e.g. the one having 13,000-20,000 viscosity-average molecular weight) with (B) a 14-30C fatty acid monoglyceride in an amount corresponding to 100-5,000 ppm. The material is injection molded into an optical disc substrate under conditions, for example, of <=340 deg.C of the set temperature of a cylinder of an injection molding machine and 90 deg.C of the set temperature of cooling water of molds, for <=4.0 seconds molding cycle and <=3.0 cooling time of the substrate in the molding cycle. |
