OPTICAL DISK SUBSTRATE

摘要

PROBLEM TO BE SOLVED: To obtain a transparent substrate for an optical disk excellent in transfer properties. SOLUTION: The glass transition temp. of a polycarbonate resin subjected to injection molding in order to form a transparent substrate is 120-142 deg.C and the transparent substrate is produced under such a condition that the difference between the glass transition temp. and the set temp. of the mold on a stamper mounted side is 0-7 deg.C. Further, this substrate is obtained by a molding method applying mold clamping pressure of 20T or more to the substrate during cooling at a time of the injection molding of the substrate.