| 摘要 |
A heat-curable polyorganosiloxane composition which includes (A) an alkenyl group-containing linear polyorganosiloxane represented by the following formula (I): wherein Ra represents a C2-C6 alkenyl and Rb represents a C1-C6 alkyl or a phenyl; (B1) a linear polyorganohydrogensiloxane represented by the following formula (II): wherein Rc is hydrogen and Rd represents a C1-C6 alkyl or a phenyl; (B2) a cyclic polyorganohydrogensiloxane including an Re2HSiO1/2 unit, wherein Re represents a hydrogen atom or C1-C6 alkyl group, and an SiO4/2 unit, and having three or more hydrogen atoms bonded to a silicon atom in one molecule; (C) a platinum series catalyst; and (D) an adhesion promoter, a ratio of a sum (HB1+HB2) of a number HB1 of the hydrogen atom(s) bonded to a silicon atom of (B1) and a number HB2 of the hydrogen atom(s) bonded to a silicon atom of (B2) based on a number ViA of the alkenyl group(s) of (A) is 0.2 to 1.0, and HB1 is 0.5 to 0.8 based on HB1+HB2.
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