| 摘要 |
PROBLEM TO BE SOLVED: To obtain a composition which effects a curing reaction at a high speed at relatively low temperatures giving a cured product excellent in mechanical strengths by including a specified organopolysiloxane, a specified branched siloxane silalkylene copolymer and an addition reaction catalyst. SOLUTION: This composition comprises an organopolysiloxane (A) having at least two alkenyls in the molecule, an Si-bonded-H-containing branched siloxane/silalkylene copolymer (B) represented by formula I and a catalytic amount of an addition reaction catalyst. The molar ratio of the total alkenyls of component A to the Si-bonded-H atoms of component B is 1:0.05 to 1:50. In formula I, R<1> is a 1-10C alkyl or an aryl; a is 3 or 4; X<1> is a silylalkyl of formula II; R<2> is a 2-10C alkylene; R<3> is a 1-10C alkyl; X<i+1> is H or a silylalkyl of formula II, the terminal of a branch is H; i is 1-10; b<i> is 0-3; and the average total number of b<i> per molecule is 1.5<i>×a or below.
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