Addition-curable silicone rubber composition and cured product
Provided is an addition-curable silicone rubber composition containing (A) an alkenyl group-containing organopolysiloxane having alkenyl groups bonded to at least two silicon atoms per molecule, (B) an organohydrogenpolysiloxane containing hydrogen atoms bonded to at least two silicon atoms per molecule, (C) a platinum catalyst, and (D) a benzotriazole derivative represented by general formula (I) (in the formula, R 1 is a hydrogen atom or monovalent hydrocarbon group, R 2 is a monovalent organic group) that makes it possible to provide silicone rubber that can lower the compression set without harming the curing rate and suppress discoloration after a heat resistance test.
1. An addition-curable silicone rubber composition comprising:
(A) 100 parts by weight of an alkenyl-containing organopolysiloxane having at least two silicon-bonded alkenyl groups per molecule,
(B) an organohydrogenpolysiloxane having at least two silicon-bonded hydrogen atoms per molecule, in an amount of 0.2 to 20 parts by weight per 100 parts by weight of component (A),
(C) a catalytic amount of a platinum catalyst, and
(D) a benzotriazole derivative having the general formula (I):
wherein R 1 is hydrogen or a C 1 -C 10 monovalent hydrocarbon group and R 2 is a monovalent organic group, in an amount of 2 to 1,000 moles per mole of platinum atom in component (C).
2. The silicone rubber composition of claim 1 wherein in formula (I), R 2 is a C 1 -C 10 monovalent hydrocarbon group or a group having the following formula:
wherein R 5 is a C 1 -C 15 monovalent hydrocarbon group or —(CH 2 ) p —Si(OR 6 ) 3 wherein R 6 is a C 1 -C 4 alkyl group or SiR 7 3 group (wherein R 7 is C 1 -C 4 alkyl) and p is an integer of 1 to 6, and * designates a bonding site.
3. The silicone rubber composition of claim 1 or 2 , further comprising (E) 1 to 100 parts by weight per 100 parts by weight of component (A) of a reinforcing filler.
4. The silicone rubber composition of claim 3 wherein component (E) is fumed silica having a specific surface area of at least 50 m 2 /g as measured by the BET method.
5. The silicone rubber composition of claim 1 wherein provided that T10 is a 10% cure time and T90 is a 90% cure time during measurement at 130° C. for 2 minutes, a value of T90-T10 is up to 40 seconds.
6. A cured silicone rubber which is formed by curing the silicone rubber composition of claim 1 and has a compression set of up to 30% after compressed 25% at 150° C. for 22 hours.