METHOD FOR CRYSTALLIZING LOW MOLECULAR WEIGHT POLYCARBONATE AND METHOD FOR PRODUCING POLYCARBONATE RESIN USING THE SAME

摘要

PROBLEM TO BE SOLVED: To provide a method for efficiently crystallizing a low mol.wt. aromatic polycarbonate, and to provide a method for producing a polycarbonate resin having a desired intrinsic viscosity using the polycarbonate crystallized by the method. SOLUTION: This method for crystallizing a low mol.wt. aromatic polycarbonate is characterized by bringing an un-crystallized low mol.wt. aromatic polycarbonate (preferably produced by a melt-polycondensation method) having an intrinsic viscosity of 0.05 to 0.38 into contact with a nitrile compound. The method for producing a polycarbonate resin having a desired intrinsic viscosity is characterized by heating the crystallized low mol.wt. aromatic polycarbonate at a lower temperature than its melting point under a reduced pressure or in an inactive gas flow to enhance the polymerization degree of the polycarbonate.