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:
Nov. 28, 2017
Filed:
May. 26, 2010
Thomas König, Leverkusen, DE;
Jörg Kirchhoff, Köln, DE;
Michael Bierdel, Leverkusen, DE;
Klemens Kohlgrüber, Kürten, DE;
Johann Rechner, Kempen, DE;
Ing. Johan Vaes, Kalmthout, BE;
Johan Vanden Eynde, Zwijnaarde, BE;
Frank Bruynseels, Sint Gillis, BE;
Bert Ruytinx, Halen, BE;
Thomas König, Leverkusen, DE;
Jörg Kirchhoff, Köln, DE;
Michael Bierdel, Leverkusen, DE;
Klemens Kohlgrüber, Kürten, DE;
Johann Rechner, Kempen, DE;
Ing. Johan Vaes, Kalmthout, BE;
Johan Vanden Eynde, Zwijnaarde, BE;
Frank Bruynseels, Sint Gillis, BE;
Bert Ruytinx, Halen, BE;
COVESTRO DEUTSCHLAND AG, Leverkusen, DE;
Abstract
The invention relates to polycarbonates with extremely low residual levels of volatile constituents and thermal degradation products, and also improved optical properties, especially Yellowness Index (YI) and good thermal stability, from solvent-containing polymer melts. The invention further relates to an apparatus and a process for preparing these polycarbonates with the aid of a devolatilizing extruder with at least three devolatilizing zones, and zones for introducing entraining agent into dispersion are present upstream of at least three devolatilizing zones.