to 6 carbon atoms, with an organopolysiloxane of average compositional formula (2): (R1)a(R2)bSiO(4???a???b)/2???(2) wherein R1 is a monovalent organic group containing an amino, epoxy, hydroxyl or carboxyl group, hydrogen, hydroxyl, alkoxy or alkenyloxy group, R2 is a substituted or unsubstituted monovalent hydrocarbon group, letters a and b are positive numbers in the range: 0.001???a???1, 1???