| 摘要 |
PURPOSE: To obtain an expandable silicon rubber composition, consisting essentially of an organopolysiloxane, a reinforcing silica, a specific azo-based foaming agent and a curing agent, having low toxicity of the decomposed foaming agent and high safety and capable of providing a silicone rubber sponge having fine bubbles (cells). CONSTITUTION: This composition consists essentially of (A) 100 pts. wt. organopolysiloxane of the average compositional formula Rm SiO(4-n)/2 [R is a (substituted) monovalent hydrocarbon; (n) is 1.98-2.02], (B) 10-100 pts.wt., preferably 30-80 pts.wt. reinforcing silica having >=50m<2> /g, preferably 100-400m<2> /g specific surface area, (C) 0.5-30 pts.wt., preferably 1-20 pts.wt. azo-based foaming agent of the formula [R<1> to R<6> are each an alkyl, a nitrile or NH2 -CO] (except azobisisobutyronitrile) [preferably 2,2'-azobis(2-methylbutyronitrile] and (D) a curing agent (e.g. a combination of an organohydrogenpolysiloxane with a platinum group metallic catalyst) in an amount effective in curing. |
