"up consisting of maleinimide and a maleic acid derivative selected from the group consisting of ##STR38## and R6 (SiR2 7 O)x (SiR7 R6 O)y SiR2 7 R6, where R1 is a hydroxyl group, R2 is a hydrocarbonoxy radical which is bonded to the carbon atom of the ##STR39## group and is substituted with at least one triorganosilyl group, at least one R6 is a radical of the formula ##STR40## and the other R6 ra" . . . .