Further suitable compounds are diallylammonium compounds as described in DE-AA 142 541, especially those of the formula (5) ##STR10## in which R15 and R25 are identical or different alkyl groups having 1 to 5, preferably 1 or 2, carbon atoms, but in particular are methyl groups, and A- is a stoichiometric equivalent of an anion, preferably a tetraphenylborate anion, and the polymeric ammonium comp