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:
Sep. 12, 1995
Filed:
Sep. 24, 1993
Tadashi Amano, Ibaraki, JP;
Shuji Ohnishi, Ibaraki, JP;
Shin-Etsu Chemical Co., Ltd., Tokyo, JP;
Abstract
An improvement is proposed in the method for the preparation of a polyvinyl chloride resin by the suspension polymerization of the monomer in a polymerization reactor system comprising a reactor and an external heat exchanger connected to the reactor by a pipe line through a pumping means in order to supplement the deficiency in the cooling capacity of the jacket of the reactor and/or reflux condenser installed thereto when the capacity of the reactor is greatly increased. While such an external circulating circuit using a conventional pump suffers from a serious problem of polymer scale deposition on the inner walls of the circuit and downgrading of the quality of the resin product, these drawbacks can be dissolved by using a specific pump having an impellor in the form of a single spiral screw blade around a hub having a conical configuration to circulate the polymerization mixture through the heat exchanger for the removal of the heat of polymerization, which is started at or after the moment when the temperature of the polymerization mixture in the reactor reaches the predetermined polymerization temperature but before the conversion of the monomer to polymer exceeds 10%.