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:
Jun. 15, 1999
Filed:
Apr. 03, 1998
Asahi Kasei Kogyo Kabushiki Kaisha, Osaka, JP;
Abstract
A method for producing an aromatic polycarbonate which comprises subjecting to a transesterification polymerization reaction at least one polymerizable material for an aromatic polycarbonate, the transesterification reaction being performed in one or more polymerizers which is or are connected through a pipeline system toward an outlet for a final aromatic polycarbonate product, wherein the pipeline system comprises one or more pipes, through which a molten aromatic polycarbonate having a number average molecular weight increased by the transesterification polymerization reaction is passed while contacting an inner wall of the pipe or pipes, the pipeline system having at least one viscous polycarbonate passage region in which a molten aromatic polycarbonate having a number average molecular weight of 6,000 or more is passed through the pipe, wherein the pipe in the at least one viscous polycarbonate passage region is heated to provide a temperature difference in the range of from -3.degree. C. to 50.degree. C. between the temperature (.degree.C.) of the outer wall of the pipe and the temperature (.degree.C.) of the aromatic polycarbonate in the polymerizer from which the aromatic polycarbonate is passed through the pipe. By the method of the present invention, a high quality aromatic polycarbonate which is not only highly colorless but also has a low foreign matter content can be easily produced.