Room temperature curable organosiloxane compositions

摘要

A composition curable to an elastomer at room temperature comprises, by weight, (1) 100 parts of a liquid organopolysiloxane having a viscosity of 100 to 2,000,000 cps. at room temperature, a R/Si of from 1.95:1 to 2:1 and a hydroxyl radical bonded to each terminal Si atom, (2) from 0.1 to 10 parts of a polyvinylalkoxysilane of the formula or an alkoxydisilane of the formula or the partial hydrolysate thereof, or a bis (alkoxysilyl) hydrocarbon of the formula or the partial hydrolysate thereof, wherein R11 is an alkyl radical, R111 is a divalent hydrocarbon radical, X is an alkyl, aryl or alkoxy radical, and n is at least 2, and (3) from 0.5 to 5 parts of a metal carboxylate wherein the metal is Pb, Sn, Zn, Fe, Cd, Ti, Ca or Mn. The siloxane may contain saturated or unsaturated hydrocarbon radicals, and the former may have halogen, cyano or nitro substituents attached to at least the third C atom of the hydrocarbon-chain removed from silicon. The carboxylic acid radical of component (3) preferably contains from 3 to 14 C atoms. Fillers, e.g. TiO2,SiO2 (fume, precipitated and aerogel), CaCO3, diatomaceous earth and C black, may also be added. In a typical example (1) a mixture of a liquid hydroxy-terminated dimethylpolysiloxane, a polyvinyltriethoxysilane and tin octoate, cured within 30 minutes at room temperature to a tough, springy, resilient elastomer. Uses; in sealing, puttying and caulking applications.