The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 09, 2007
Filed:
Dec. 02, 2004
Uwe Hucks, Alpen, DE;
Melanie Möthrath, Düsseldorf, DE;
Helmut-werner Heuer, Krefeld, DE;
Thomas König, Leverkusen, DE;
Lydia Simon, Brasschaat, BE;
Marc Buts, Duffel, BE;
Johan Vanden Eynde, Zwijnaarde, BE;
Uwe Hucks, Alpen, DE;
Melanie Möthrath, Düsseldorf, DE;
Helmut-Werner Heuer, Krefeld, DE;
Thomas König, Leverkusen, DE;
Lydia Simon, Brasschaat, BE;
Marc Buts, Duffel, BE;
Johan Vanden Eynde, Zwijnaarde, BE;
Bayer MaterialScience AG, Leverkusen, DE;
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.