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. 16, 1999
Filed:
Sep. 09, 1996
Toshihiko Nakano, Ibaraki-ken, JP;
Tadashi Amano, Ibaraki-ken, JP;
Shin-Etsu Chemical Co., Ltd., Tokyo, JP;
Abstract
The production process includes starting suspension polymerization of vinyl chloride-based monomer in a polymerization vessel in the presence of a particular combination of suspending agents; and, at the time when a polymerization conversion has reached 5 to 60%, further adding to the reaction mixture a partially saponified polyvinyl alcohol having an average polymerization degree of 1,500 to 4,000 and a saponification degree of 75 to 98 mole %, wherein a carboxylic acid ester of polyhydric alcohol is further added to at least one one selected from a content inside the polymerization vessel prior to the start of the polymerization, a content inside the polymerization vessel during the polymerization, and the resulting polymer. According to the process, there is obtained a vinyl chloride polymer having a large bulk specific gravity and a fast gelation rate, and from the polymer, a formed part small in both the number of fish eyes and the amount of residual monomer can be obtained.