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:
Aug. 20, 1991
Filed:
Feb. 22, 1990
Shigeki Kuze, Ichihara, JP;
Eiichi Terada, Ichihara, JP;
Idemitsu Petrochemical Co., Ltd., Tokyo, JP;
Abstract
A process for producing a branched polycarbonate by an interfacial polycondensation method comprising condensing a first reaction mixture comprising an inert organic solvent, an alkaline aqueous solution of divalent phenol, a branching agent, and phosgene, the branching agent having a partition coefficient of at least 1, wherein the partition coefficient is defined as the ratio of the concentration in inert organic solvent/concentration in water, to form a second mixture containing a polycarbonate oligomer or a polycarbonate and unreacted branching agent, separating the second mixture into an organic solvent layer and an aqueous layer which contains the unreacted branching agent, extracting the unreacted branching agent from the aqueous layer with inert organic solvent and recycling the inert organic solvent which contains the unreacted branching agent extracted from the aqueous layer to the first reaction mixture. The present invention has the advantages of preventing waste water pollution and at the same time, increasing the efficiency of use of the branching agent, because it permits the efficient extraction recovery of the unreacted branching agent contained in waste water. The branched polycarbonate obtained by the process by the present invention has good melt characteristics, is great in dependency on a rate of shear, and has a small drawn down. Thus, the branched polycarbonate is suitable for extrusion molding.