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:
Mar. 11, 2003
Filed:
Dec. 19, 2001
Andreas Chrisochoou, Köln, DE;
Steffen Kühling, Meerbusch, DE;
Johan Vanden Eynde, Zwijnaarde, BE;
Bayer Aktiengesellschaft, Leverkusen, DE;
Abstract
A two stage interfacial polycondensation process for the production of carbonic acid diaryl ester is disclosed. The invention concerns an improvement to the process that entails forming in a first stage a reaction mixture that contains an inert solvent, at least one monophenol, phosgene, and aqueous alkali hydroxide solution, passing said reaction mixture to a second stage through at least one constriction at a velocity of 3 to 15 m/s under conditions designed to expose the mixture to a pressure drop of 0.1 to 2.5 bar, and in said second stage passing said mixture through at least one dispersing element at a velocity of 2 to 10 m/s under conditions designed to expose the mixture to a pressure drop of 0.1 to 0.5 bar. The resulting product is characterized by its purity and suitability for the manufacture of polycarbonates in the melt transesterification process.