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:
May. 18, 1993
Filed:
Feb. 27, 1992
Akihito Tsukuno, Annaka, JP;
Shin-Etsu Chemical Co., Ltd., Tokyo, JP;
Abstract
A process for preparing a high molecular weight organopolysiloxane comprising: a first polymerization step of bringing a low molecular weight organopolysiloxane into reaction in the presence of a quaternary phosphonium hydroxide compound and/or a silanolate thereof as a catalyst under heating; and a second polymerization step for bringing the resulting reaction mixture into reaction in the presence of an alkali metal hydroxide and/or a silanolate thereof as a catalyst under heating. According to the process, a high molecular weight organopolysiloxane can be prepared using a reduced amount of catalyst for polymerization reaction, so that the amount of salts formed from a neutralizing agent is smaller and the subsequent filtration step for purification is less burdensome and easier to carry out. Further, it is possible to obtain high molecular weight organopolysiloxanes of excellent qualities as to transparency, electrical insulation property, arrangement of structural units in the case of preparation of copolymer, and odor.