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:
Aug. 08, 1989
Filed:
Jun. 02, 1988
Shin-Etsu Chemical Co., Ltd., Tokyo, JP;
Abstract
An organopolysiloxane composed of tetrafuctional siloxane units SiO.sub.2 and monofunctional siloxane units R.sub.3 SiO.sub.0.5 can be prepared by reacting an alkyl orthosilicate, e.g., ethyl silicate, or a partial hydrolysis product thereof and an oligomeric organopolysiloxane containing the monofunctional siloxane units in the presence of a catalytic compound which is, different from conventional hydrogen chloride, selected from the group consisting of sulfonic acid group-containing compounds, e.g., sulfuric acid and p-toluene sulfonic acid, and phosphonitrile chloride. In particular, cation exchange resins of sulfonic acid type and fluorinated polysulfonic acid resins can be used as the catalyst in a continuous process in which the reaction mixture is passed through a bed of the catalyst continuously. The inventive method is advantageous over conventional methods because of the absence of the problems of heavy corrosion of the apparatuses and waste disposal due to the hydrogen chloride.