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. 20, 1995
Filed:
Nov. 29, 1993
Motokazu Hirao, Yokohama, JP;
Yoshiyuki Totani, Yokohama, JP;
Tomonori Ito, Yokohama, JP;
Masakatsu Nakatsuka, Yokohama, JP;
Akihiro Yamaguchi, Kamakura, JP;
Mitsui Toatsu Chemicals, Inc., Tokyo, JP;
Abstract
1. A method for preparing an aromatic polycarbonate having less content of a low molecular weight oligomer which comprises the steps of: (A) conducting an interfacial polymerization reaction in a reaction system comprising at least one aromatic dihydroxy compound, a carbonate precursor, an alkali metal or alkaline earth metal base, water and an organic solvent in the absence of an endcapping agent, and (B) conducting an interfacial polymerization reaction with the addition of an endcapping agent after at least one of the following parameters reaches a predetermined value: (1) a weight-average molecular weight of a prepolymer obtained in step A, (2) a residual amount of the aromatic dihydroxy compound which is contained in the reaction mixture obtained in step A, (3) an amount ratio of a bishaloformate compound to a prepolymer wherein the bishaloformate compound is a bishaloformate derivative of a dihydroxy compound and is contained in the reaction mixture obtained in step A.