s a hydrocarbyl group of 1-20 carbons, X is a halogen atom and m is a positive number of 3???m???1.5, and an organosilicon compound of the formula R2 XR3 YSi(OR4)Z wherein R2 and R4 is a hydrocarbyl group, R3 is a hydrocarbyl group or a hydrocarbyl group containing a hetero atom, X, Y and Z have a relationship of 0???X???2, 1???Y???3, 1???Z???3, and X+Y+Z=4, to produce 90 to 50% by weight of a pro