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

US7279544B2 · kind B2 · utility

Assignee

• Bayer MaterialScience AG · DE

Inventors

• Uwe Hucks · Alpen, DE
• Melanie Mothrath · Mülheim an der Ruhr, DE
• Helmut-Werner Heuer · Krefeld, DE
• Thomas König · Nuremberg, DE
• Lydia Simon · Shanghai, CN
• Marc Buts · Duffel, BE
• Johan Vanden Eynde · Zwijnaarde, BE

Key dates

• Filing date: Dec 2, 2004
• Grant date: Oct 9, 2007
• Expiry date: Dec 2, 2024

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C08G64/307
• WIPO field: Macromolecular chemistry, polymers
• WIPO sector: Chemistry

Abstract

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.