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:
Jul. 09, 1996
Filed:
Jan. 30, 1995
Dennis P Thompson, Clifton Park, NY (US);
Patricia P Anderson, Williamstown, MA (US);
Donald Slick, Clifton Park, NY (US);
General Electric Company, Waterford, NY (US);
Abstract
Linear triorganosiloxy-terminated polydiorganosiloxanes having a silanol content of less than about 200 ppm are prepared by condensing linear higher molecular weight polydiorganopolysiloxanediols having one Si-bonded hydroxyl group in each terminal unit and a silanol content of preferably greater than about 1000, in two separate stages, one using a fixed bed of a solid form of a conventional equilibration catalyst, and the other using a condensation/disproportionation catalyst, e.g., a phosphonitrilic halide or an oligomer thereof or a reaction product thereof with water, an alcohol, an acid, or a siloxane or silane, until the polydiorganosiloxane has reached the desired low content of silanol groups, e.g., below 200 ppm, by weight. The two stages can be carried out in either order, and a conventional monofunctional chain terminating agent can be present in either or both stages. The process preferably does not increase the cyclic byproduct content.