Millable-type silicone rubber composition and silicone rubber cured product

Abstract

A millable-type silicone rubber composition, including: (A) 100 parts by mass of an organopolysiloxane represented by following average composition formula (1), the organopolysiloxane having polymerization degree of 100 or more, wherein a content of a low molecular siloxane contained as an impurity and having a polymerization degree of 10 or less is less than 1,000 ppm; (B) 5 to 100 parts by mass of a treated silica treated with a vinyl group-containing alkoxysilane and/or a vinyl group-containing organosilazane, the treated silica having a hydrophobicity degree of 40 or more; and (C) an effective amount of a curing agent. This provides a millable-type silicone rubber composition that yields a silicone rubber cured product with: a total of low molecular siloxane components having polymerization degree of 10 or less of less than 1,000 ppm; a small change in plasticity degree of the silicone rubber compound; and a small compression set. R1aSiO(4-a)/2  (1)

Dependencies are inferred from the claim text.