As representative examples thereof, there are those represented by the following general formula: R (CH3)2SiO{ (CH3)2SiO}a{ (CH3) R5SiO}bSi (CH3) 2R4 wherein R5 is a group selected from a vinyl group, a phenyl group, an alkyl group having 6 to 20 carbon atoms, an aminoalkyl group having 3 to 15 carbon atoms, a perfluoroalkyl group having 3 to 15 carbon atoms, and a quaternary ammonium base-contain