Bayer Materialscience Ag

Lydia Simon

Helmut-Werner Heuer

Marc Buts

Melanie Möthrath

Uwe Hucks

Thomas König

Johan Vanden Eynde

Lothar Bunzel

Thomas Pfingst

Peter Snobl

A multi stage process for the production of polycarbonates having low monomer content is disclosed. The process entails, in sequence, (i) transesterifying in the melt at least one dihydroxyaryl compound with at least one diaryl carbonate in the presence of at least one onium catalyst to produce a polycondensate that contains monomers, (ii) introducing into the polycondensate an inhibitor in an hypostoichiometric amount in relation to the catalyst and (iii) reducing in a finishing reactor the content of monomers in said polycondensate. The polycarbonate thus produced is characterized in that it contains less than 350 ppm of diphenyl carbonate, less than 40 ppm of 2,2-bis-(4-hydroxyphenyl)propane and less than 150 ppm of phenol.

Transesterification process for the production of polycarbonates having a low content of volatile compounds

An improvement to the melt transesterification process for the preparation of polycarbonate is disclosed. The improvement entails adding to the process between its medium viscosity reactor and a high viscosity reactor at least one bridged ester of organic sulphur-containing acid.

Inhibition of catalytically active impurities in polycarbonate by the melt transesterification process

Growing community of inventors

Brasschaat, Belgium

Lydia Simon