Patent ID: 6887970

Claim:
Continuous process for the production of polycarbonates by the transesterification of diaryl carbonates with dihydroxyaryl compounds characterised in that condensation is affected in the presence of quaternary onium compounds as catalysts, wherein the final polycondensation stage is affected without the further addition of catalyst, and in that an oligocarbonate is produced using quaternary onium compounds as catalysts which can be decomposed, substantially without leaving a residue, after preliminary condensation without separation of the monohydroxyaryl compound formed, and in a plurality of subsequent flash/evaporator stages in which the temperature is elevated stepwise and the pressure is decreased stepwise, which oligocarbonate is thereafter condensed to form the finished polycarbonate in one or two successive basket-type reactors, without the addition of further amounts of the catalyst used or of a new, different catalyst, whilst the temperature is further elevated and the pressure is further reduced.