Patent ID: RE40697

Claim:
A method for the preparation of polycarbonate, said method comprising extruding in the presence of a transesterification catalyst at one or more temperatures in a temperature range between about 100° C. and about 400° C. a solution comprising a solvent and an oligomeric polycarbonate, said extruding being carried out on an extruder equipped with at least one vent adapted for solvent removal, said oligomeric polycarbonate comprising polycarbonate repeat units derived from at least one dihydroxy aromatic compound, said oligomeric polycarbonate comprising ester substituted phenoxy terminal groups having structure I wherein R 1 is a C 1 -C 20 alkyl group, C 4 -C 20 cycloalkyl group, or C 4 -C 20 aryl group; R 2 is independently each occurrence a halogen atom, cyano group, nitro group, C 1 -C 20 alkyl group, C 4 -C 20 cycloalkyl group, C 4 -C 20 aryl group, C 1 -C 20 alkoxy group, C 4 -C 20 cycloalkoxy group, C 4 -C 20 aryloxy group, C 1 -C 20 alkylthio group, C 4 -C 20 cycloalkylthio group, C 4 -C 20 arylthio group, C 1 -C 20 alkylsulfinyl group, C 4 -C 20 cycloalkylsulfinyl group, C 4 -C 20 arylsulfinyl group, C 1 -C 20 alkylsulfonyl group, C 4 -C 20 cycloalkylsulfonyl group, C 4 -C 20 arylsulfonyl group, C 1 -C 20 alkoxycarbonyl group, C 4 -C 20 cycloalkoxycarbonyl group, C 4 -C 20 aryloxycarbonyl group, C 2 -C 60 alkylamino group, C 6 -C 60 cycloalkylamino group, C 5 -C 60 arylamino group, C 1 -C 40 alkylaminocarbonyl group, C 4 -C 40 cycloalkylaminocarbonyl group, C 4 -C 40 arylaminocarbonyl group, or C 1 -C 20 acylamino group; and b is an integer 0-4.