Patent ID: 7485695
Filing Date: 2009-02-03
Classification: B29C,B29K,C08G

Abstract:
1. A method for preparing polycarbonate wherein the method comprises the steps of, (i) introducing to an extruder through one or more feed sections, a plurality of reaction components comprising a dihydroxy compound, an activated carbonate, and a transesterification catalyst, wherein the extruder comprises: (a) a first feed section; (b) a polycarbonate exit section; and (c) a reaction section disposed between the first feed section and the polycarbonate exit section, the reaction section comprising one or more devolatilization units, wherein each devolatilization unit comprises an array of vent-conveying sections and conveying sections arranged in a configuration selected from the group consisting of: (ii) extruding the plurality of reaction components at a temperature in a range between 100° C. and 500° C., wherein during the extrusion of the reaction components a volatile residue from the activated carbonate is removed from each devolatilization unit, and polycarbonate is removed through the polycarbonate exit section.