n+p)???0.05, and m, n and p are selected so that a viscosity of the organopolysiloxane (I) ranges from 5 to 100 mPa???s at 25 degrees C. In the formula (1), R1 is an alkenyl group, preferably having 2 to 8 carbon atoms, such as a vinyl, an allyl, a butenyl, a pentenyl and a hexenyl group.