Patent ID: 6251990
Filing Date: 2001-06-26
Classification: C08G,C08K,C08L

Abstract:
A silicone rubber composition for use as a high-voltage electrical insulator, comprising(A) 100 parts by weight of an organopolysiloxane represented by the following average compositional formula (1):R.sup.1.sub.a SiO.sub.(4-a)/2 (1)wherein R.sup.1 is a substituted or unsubstituted monovalent hydrocarbon group, 0.01 to 10 mol % of R.sup.1 is alkenyl, at least 90 mol % of R.sup.1 is methyl, and a is a positive number of 1.9 to 2.4, said organopolysiloxane having on the average at least two alkenyl groups in a molecule and a degree of polymerization of up to 1,200,(B) 0.1 to 50 parts by weight of an organohydrogenpolysiloxane having at least two hydrogen atoms each attached to a silicon atom of the following average compositional formula (2):R.sup.2.sub.b H.sub.c SiO.sub.(4-b-c)/2 (2)wherein R.sup.2 is a substituted or unsubstituted monovalent hydrocarbon group having 1 to 10 carbon atoms, b is a positive number of 0.7 to 2.1, c is a positive number of 0.001 to 1.0, and the sum of b+c is from 0.8 to 3.0, said organohydrogenpolysiloxane being liquid at room temperature,(C) 40 to 400 parts by weight of aluminum hydroxide,(D) a catalytic amount of an addition reaction catalyst,(E) 0.1 to 50 parts by weight of a thixotropic agent, and(F) 0 to 30 parts by weight of a tackifier, said composition exhibiting a thixotropy corresponding to a sag of up to 1 inch after 1 minute as measured by the Boeing flow jig test.