Besides the carbon atoms and hydrogen atoms, the aliphatic groups can contain linking groups or other groups, for example hydroxyl groups, or other amino groups. [0018] Examples of suitable cationic surfactants are alkyldimethylbenzylammonium chlorides or bromides, the alkyltrimethylammonium salts, for example cetyltrimethylammonium chloride or bromide, tetradecyltrimethylammonium chloride or brom