Patent ID: 6117968
Filing Date: 2000-09-12
Classification: C08G

Abstract:
A method for preparing a copolyestercarbonate which comprises:passing phosgene, under reactive conditions including a pH in the range of about 4.5-9.5, into a mixture comprising at least one dihydroxyaromatic compound, at least one dicarboxylic acid, water and a water-immiscible organic solvent, in the presence of both at least one phase transfer catalyst and at least one aliphatic or alicyclic tertiary amine, the proportion of said phase transfer catalyst being in the range of about 6.5-10.5 mole percent based on total dihydroxyaromatic compound and dicarboxylic acid and the proportion of phosgene being at least about 50% by weight of stoichiometric; andraising the pH to at least about 10 and continuing phosgene passage until a stoichiometric excess of at least 5% phosgene by weight has been introduced.