Patent ID: 7485694
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 an activated carbonate, a dihydroxy compound, an activated carbonate residue, 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 at least one conveying section having a screw element configuration consisting of one or more conveying elements, a plurality of kneading sections wherein each kneading section has a screw element configuration comprising a kneading element, and a plurality of venting sections, wherein: (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, activated carbonate residue is removed through the plurality of venting sections, and polycarbonate is removed through the polycarbonate exit section.