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:
Jul. 04, 1989
Filed:
Apr. 20, 1988
Shin-Etsu Chemical Co., Ltd., Tokyo, JP;
Abstract
A process for preparing a vinyl chloride polymer by suspension polymerization with use of (A) a particular partially saponified polyvinyl alcohol having a high polymerization degree and a high saponification degree, (B) a particular hydoxypropyl methyl cellulose and (C) a particular partially saponified polyvinyl alcohol having a low polymerization degree and a low saponification degree as dispersion stabilizers, in a polymerization vessel coated with a scale preventive on its inner wall etc., wherein an (A)Agent/(B)agent ratio is 4/6 to 24/1 in weight ratio; Agent (C) is used in an amount of 0.001 to 0.1% by weight based on the charged monomers; Agent (C) is charged with or after the charging of Agent (A) and (B), and, the particle diameter of Agent (C) in the suspension mixture is controlled to not higher than 100 .mu.m. A vinyl chloride polymer having a high bulk density and high porosity can be produced without formation of polymer scale.