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:
Apr. 30, 1991
Filed:
May. 08, 1989
Tadashi Amano, Ibaraki, JP;
Junichi Watanabe, Ageo, JP;
Shin-Etsu Chemical Co., Ltd., Tokyo, JP;
Abstract
A process for preparing a vinyl chloride containing polymer, comprising: suspension polymerizing vinyl chloride or a vinyl monomer mixture containing vinyl chloride in an aqueous medium; and adding an antioxidant dispersion essentially consisting of an antioxidant having a melting point of not lower than 30.degree. C. and a suspending agent in water to the polymerization system, wherein said antioxidant dispersion has been heated once to a temperature not lower than the melting point of the antioxidant and then cooled, prior to the additon to the polymerization system. This process makes it possible to charge the antioxidant in an accurate amount by a mechanical means, and improve the quality of the manufactured polymer.