. " radical and Y is a halogen atom, d is 0, 1 or 2, and e is 1, 2 or 3, with the proviso that the sum of d and e is less than or equal to 3, and if appropriate at least one silane of the formula R6 f Si(OR7)4-f (III) and/or a partial hydrolysate thereof, in which R6 is a hydrogen atom or a monovalent organic radical, R7 is a hydrogen atom or a monovalent organic radical and f" . . . .