The organosilane is represented by the formula of R1 Si(OR2)3 in which R1 is an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms or an aryl group having 6 to 10 carbon atoms, and R2 is an alkyl group having 1 to 5 carbon atoms or an acyl group having 1 to 4 carbon atoms.