Process for producing polycarbonate

Abstract

The invention relates to a process for producing polycarbonate comprising the steps of a) providing a solution of polycarbonate in an organic solvent wherein the solution comprises 5-40 wt. % of polycarbonate, based on the weight of the solution, b) concentrating and heating the solution of step a) to form a concentrated polycarbonate melt comprising the solvent wherein the concentrated polycarbonate melt comprises at most 5 wt. % and more than 500 ppm of solvent, based on the weight of the concentrated polycarbonate melt and c) further concentrating the concentrated polycarbonate of step b) to a polycarbonate comprising at most 500 ppm of organic solvent, wherein step b) is carried out by subjecting the solution to at least two devolatalization stages in series, wherein each devolatalization stage comprises heating the solution by means of a heat exchanger and subsequently feeding the heated solution to a degassing vessel, wherein at least part of the solvent is separated from the solution by evaporation, and step c) is carried out at least in a degassing extruder.

Dependencies are inferred from the claim text.