The polyisocyanate polyaddition products comprise hydrophobic compounds plus at least one further compound selected from the group consisting of: (i) organic, cyclic compounds having a molecular weight of from 200 to 3000 g/mol, (ii) salts of metals of transition groups I, II and/or VIII, (iii) organic and/or inorganic acid anhydrides, (iv) cyclic sulfonic esters and/or sulfones, (v) lactones, lactams and/or cyclic esters and/or (vi) null,null-unsaturated carboxylic acids, null,null-unsaturated carboxylic acid derivatives, null,null-unsaturated ketones and/or null,null-unsaturated aldehydes.