| CPC C08L 83/04 (2013.01) [C08L 2205/025 (2013.01); C08L 2205/035 (2013.01)] | 7 Claims |
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1. An addition-curable liquid silicone rubber composition comprising:
(A) 100 parts by weight of an alkenylated linear organopolysiloxane containing one silicon-bonded alkenyl group only at each of both molecular chain ends, having an average degree of polymerization of up to 1,500, and being liquid at 25° C.,
(B) 1 to 30 parts by weight of an alkenylated linear organopolysiloxane containing two or three silicon-bonded alkenyl groups at each of both molecular chain ends, having an average degree of polymerization of up to 1,500, and being liquid at 25° C.,
(C) an organohydrogenpolysiloxane consisting of
(C-1) an organohydrogenpolysiloxane containing at least three silicon-bonded hydrogen atoms per molecule and
(C-2) a linear organohydrogenpolysiloxane capped with diorganohydrogensiloxy at both molecular chain ends and containing silicon-bonded hydrogen atoms only at both molecular chain ends,
the moles of silicon-bonded hydrogen in component (C-1), designated [Si—H groups (C-1)], to the total moles of silicon-bonded hydrogen atoms in components (C-1) and (C-2), designated [total Si—H groups], is 60 to 95 mol % calculated as [Si—H groups (C-1)]/[total Si—H groups]×100, and a molar ratio of the moles of [total Si—H groups] to the total moles of alkenyl groups in the composition, designated [total alkenyl groups], is from 1.0 to 3.0 calculated as [total Si—H groups]/[total alkenyl groups],
(D) reinforcing silica obtained from hydrophobic treatment of fumed silica having a BET specific surface area of at least 130 m2/g, in an amount of 5 to 60 parts by weight per 100 parts by weight of components (A) and (B) combined, and
(E) an addition reaction catalyst in an amount to give 0.5 to 1,000 ppm of platinum group metal based on the total weight of components (A) and (B).
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