the other z radicals a hydrogen atom or an anionic, nonionic or cationic aliphatic, alicyclic, aromatic, araliphatic or aralicyclic acyl radical of 1 to 60 carbon atoms or a group of the formula --SO3 M, where M is a cation, each R' is independently of the other R' radicals an amine or amide nitrogen atom or an aliphatic, alicyclic or aromatic radical or a combination of two or more such hydrocar