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:
Dec. 27, 1994
Filed:
Sep. 24, 1993
Minoru Shigemitsu, Ibaraki, JP;
Tadashi Amano, Ibaraki, JP;
Shin-Etsu Chemical Co., Ltd., Tokyo, JP;
Abstract
A process for suspension polymerizing vinyl chloride or a monomeric mixture containing the same in an aqueous medium comprising the step of adding a partially saponified polyvinyl alcohol having an average polymerization degree of 600 to 800 and a saponification degree of 65 to 75 mol % to a polymerization system, wherein the partially saponified polyvinyl alcohol is added before start of polymerization, and also after-added continuously or intermittently over the period from the start of polymerization to the time when a polymerization conversion of 10 to 30% is reached. By the suspension polymerization process, it is possible to obtain a vinyl chloride-based polymer having high bulk specific gravity, high gelation rate and a certain level of thermal stability and showing an effectively reduced number of fish eyes when formed into shaped products.