Patent ID: 6740730
Filing Date: 2004-05-25
Classification: C08G

Abstract:
A solvent-free low-branching, thermoplastic, aromatic polycarbonate having a weight-average molecular weight (Mw) of from 2000 to 150,000, and being prepared by melt transesterification of a composition comprising,(i) diphenols, (ii) chain terminators of formula (I) wherein R, Râ€² and Râ€³ each independently of the others represent H, optionally branched C1-C34-alkyl/cycloalkyl, C7C34-alkaryl or C6-C34-aryl, and,(iii) optionally branching agents, wherein the transesterification process is performed in the presence of a catalyst represented by the following formula for which R1, R2, R3 and R4 are each independently selected from the group consisting of C1-C18-aryl, C6-C14-aryl, C7-C12-aralkyl and C5-C6cycloalkyl, and Xâˆ’ is an anion selected from the group consisting of sulfate, hydrogen sulfate, hydrogen carbonate, carbonate, acetate, boranate, hydrogen phosphate, halide, and an alcoholate of the formula OR5 wherein R5 is selected from C6-C14-aryl and C7-C12-aralkyl, andfurther wherein after total saponification the aromatic polycarbonate contains less than 300 ppm, determined by HPLC, of elements conforming to formula (II) HOâ€”Z(COOH)â€”OHâ€ƒâ€ƒ(II) wherein Z is an aromatic radical having 6 to 30 carbon atoms and where the acid group is in the ortho position relative to a hydroxy group.