| 摘要 |
PURPOSE:To provide a sealing material made of an oil-bleeding fluorosiliocone rubber which has excellent resistance to oils, solvents, weather, heat and cold, by vulcanizing and molding a compound consisting of a specified organopolysiloxane, reinforcing silica and an oily organopolysiloxane. CONSTITUTION:A compound consisting of 100pts.wt. organopolysiloxane (A) having a viscosity of not lower than 100 cps and the average compositional formula I [wherein R is composed of at least 25mol% of a perfluoroalkylalkyl group and 75-50mol% of CH3, C2H5, phenyl and vinyl groups; a is a number of 1.98-2.02; and b is a number of (4-a)/2], 10-50pts.wt. reinforcing silica (B) having a surface area of not smaller than 50m<2>/g, such as fumed silica, 3-10pts. wt. oily organopolysiloxane (C) of formula II (wherein R<2> is composed of 70-25% CH3 and 30-75% pnenyl; and n is a number of 0-5) and optionally not more than 100pts.wt. semi-reinforcing silica powder (D) having an average particle size of not larger than 5mu, such as quartz powder is mixed with a vulcanizing agent (E). The mixture is vulcanized by heating and molded to obtain a sealing material suitable for use in the production of a non-tackly bevel sealing valve of a check valve.
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