Silicone-based working fluid for fluid coupling

Claim 1

A silicone-based composition for fluid coupling which comprises: (A) a methyl phenyl polysiloxane having a viscosity of from 100 to 1,000,000 centistokes at 25° C. and represented by the average unit formula (CH.sub.3).sub.a (C.sub.6 H.sub.5).sub.b SiO.sub.(4-a-b)/2' in which the subscripts a and b are each a positive number satisfying the relationships that the sum a+b is in the range from 1.95. to 2.2 and the ratio b/(a+b) is in the range from 0.05 to 0.20; and (B) from 0.01 to 5 parts by weight, per 100 parts by weight of (A), of an amino-modified organopolysiloxane of the formula R.sup.1 O--[--SiR.sup.2.sub.2 --O--].sub.n --R.sup.1, or R.sup.2.sub.3 Si--O--[--SiR.sup.2.sub.2 --O--].sub.p --[--SiR.sup.2 (--O--R.sup.1)--O--].sub.q --SiR.sup.2.sub.3, in which R 1 is: --Pn--NH--Ph; --Pn--NH--Pn--NH--Ph; --Pn--NH--(α--Np) or --Pn--NH--(β--Np), wherein Ph is phenyl, Pn is 1,4-phenylene, (α--Np) is α-naphthyl and (β--Np) is β-naphthyl, R 2 is a monovalent saturated aliphatic hydrocarbon group of up to 20 carbon atoms or phenyl, subscript n is a positive integer not exceeding 50, subscript p is zero or a positive integer not exceeding 47 and subscript q is a positive integer not exceeding 10, with the proviso that p+q does not exceeed 48.