| abstract |
A silicone rubber sponge-forming emulsion composition is provided that, even when the quantity of reinforcing silica filler is increased, does not exhibit a decline in the emulsion stability, avoids defects in the cell morphology of the sponge, and avoids a substantial increase in the hardness of the sponge. A method of producing a silicone rubber sponge from this composition is also provided. A silicone rubber sponge-forming emulsion composition comprising (A) 100 weight parts of a liquid diorganopolysiloxane that has at least two silicon-bonded alkenyl groups in each molecule, (B) 1 to 50 weight parts of a reinforcing silica filler comprising (b1) a fumed silica and (b2) a precipitated silica in a (b1)/(b2) weight ratio of 0.01/1 to 30/1, (C) 50 to 250 weight parts of water that contains (c) a smectite clay, (D) 0.1 to 7 weight parts of a sorbitan fatty acid ester, (E) 0 to 10 weight parts of an isononanoic acid ester, (F) 0 to 10 weight parts of a Guerbet alcohol, and (G) a curing agent in a quantity sufficient to crosslink and cure component (A). Also, a method of producing a silicone rubber sponge by heating this composition and curing it while removing the water, or by heating this composition and curing it and then removing the water from the resulting wet silicone rubber-like cured material. |