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:
Oct. 21, 1997
Filed:
Nov. 29, 1995
Beth Irene Gutek, Freeland, MI (US);
Loren Dale Lower, Midland, MI (US);
Sherwood Spells, Midland, MI (US);
Dow Corning Corporation, Midland, MI (US);
Abstract
A process of making a polydiorganosiloxane-silica foundation mixture from a free-flowing, powdered, surface-modified, reinforcing silica-polydiorganosiloxane concentrate used to make, for example, RTV silicone sealant compositions which have non-sag properties. The foundation mixtures are made by combining, mixing, and heating a reinforcing silica filler and a diol surface modifying agent to a temperature of 20.degree. C. to <180.degree. C. using 0.05 to 0.5 parts by weight of the diol per one part by weight of the silica. Polydiorganosiloxane is added gradually to the resulting fluidized filler over a time period of less than 10 minutes to obtain the free flowing powdered reinforcing silica-polydiorganosiloxane concentrate. The foundation mixture is obtained by massing the concentrate and adding more polydiorganosiloxane to obtain a mixture which has from 5 to 20 weight percent silica filler. The foundation mixtures have a plateau stress of >700 dynes/cm.sup.2 and a shear-thinned viscosity of no more than 1,000 Pa.s at a shear stress of 50,000 dynes/cm.sup.2. RTV silicone sealant compositions can be obtained in 10 to 15 minutes from the start of making the surface modified silica filler to the complete sealant composition.