| 摘要 |
A silicone rubber sponge of a high open cell ratio is provided to be produced by hot air vulcanizing without controlling a vulcanizing rate of rubbers and considering a fine balance of a generation rate of blowing gas, and to ensure excellent productivity. A silicone rubber sponge of a high open cell ratio has an open cell ratio of 20% or more and is obtained by expanding and hardening a silicone rubber composition. The silicone rubber composition comprises (A) 100 parts by mass of a base material which is represented by the formula I of R^1_aSiO_(4-a)/2 and obtained by mixing a reinforcing silica with organopolysiloxane having at least two alkenyl groups bonded to a silicon atom in a molecule, and then hardening the mixture, (B) 0.5-50 parts by mass of an organic blowing agent, (C) an effective amount of a hardener, and (D) 0.1-20 parts by mass of a wet silica. In the formula I, R^1 s are the same or different unsubstituted or substituted monovalent hydrocarbon groups, and a is a positive number of 1.95-2.04.
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