POLYCARBONATE MOLDING MATERIAL FOR OPTICAL DISC

摘要

PURPOSE:To obtain an arom. polycarbonate resin having its free chlorine content adjusted to less than a specified amt., so that an optical disc made thereof is excellent in long-term reliability regardless of the material used for recording film. CONSTITUTION:An arom. polycarbonate resin obtd. by the reaction of bisphenol with phosgene has its free chlorine content decreased to 0.2ppm or lower. The decrease of the free chlorine is attained by separating a purified polycarbonate resin soln. from washing water by means of centrifugal separation and filtration in combination.