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. 08, 1994
Filed:
Sep. 28, 1992
Hajime Kitamura, Ichihara, JP;
Ichiro Kaneko, Hazaki, JP;
Shin-Etsu Chemical Co., Ltd., Tokyo, JP;
Abstract
A process for preparation of a vinyl chloride polymer comprising the steps of subjecting an aqueous medium containing vinyl chloride monomer or a mixture of vinyl chloride monomer with other vinyl monomer, a polymerization initiator and a dispersant to high-speed shear agitation at a shear rate of 10.sup.4 sec.sup.-1 or above to prepare a suspended dispersion containing fine particles of the monomer(s) dispersed therein, then subjecting the suspended dispersion to low-speed shear agitation at a shear rate of from 10 to 100 sec.sup.-1, and thereafter starting suspension polymerization. Even with a decreased amount of dispersant, the process inhibits the coarsening of the polymer particles, to yield the polymer with a narrow particle diameter distribution. Deposition of scale and formation of fish-eyes are also prevented effectively.