PRODUCTION OF POLYCARBONATE

摘要

PROBLEM TO BE SOLVED: To obtain a polycarbonate improved in hue and heat stability by adding an aqueous solution of an acidic compound to a molten polycarbonate resin obtained by a transesterification process to neutralize the basics catalyst and kneading the mixture. SOLUTION: In continuously degasifying a polycarbonate (e.g. one having a viscosity-average molecular weight of 10,000-100,000) obtained by polycondesing a carbonic diester (e.g. diphenyl carbonate) with a dihydroxyaryl compound (e.g. bisphenol A) in the presence of a basic tansesterification catalyst (e.g. cesium carbonate) with a vented extruder, a solution obtained by dissolving an acidic compound (methyl benzenesulfonate) in an amount to give a concentration of 7×10<-8> to 7×10<-5> mol/g in a solvent (e.g. water) is added to the system. The amount of the solvent used is 0.05-4 pts.wt. per 100 pts.wt. polycarbonate. The extruder needs to be one provided with vents and is particularly desirably a mesh type twin-screw extruder. It is usually a multi-vent one provided with 2-10 vents.