KONTINUIERLICHES VERFAHREN ZUR HERSTELLUNG VON POLYCARBONAT

In a continuous flow reactor one or more bisphenols is converted by the action of phosgene and aqueous base into a mixture of mono- and bisphenol chloroformates which are then treated with a catalyst, additional aqueous caustic and a monophenol to afford endcapped polycarbonates. At relatively high levels of added monophenol endcapped polycarbonate oligomers are obtained. The method is especially suited for the continuous preparation of endcapped oligomers of tetrabromobisphenol A polycarbonate. The method is characterized by efficient use of phosgene, and conversion of chloroformate groups to carbonate linkages aided by trialkylamine catalysts bearing at least one methyl group on nitrogen, such as N,N-dimethylbutylamine (DMBA).