Abstract: The invention relates to polysiloxanes containing carboxyl groups that are useful for imparting water-repellency to substrates, a process for their preparation, a water-repellent system containing such polysiloxanes, and a process for the production of hydrophobic substrates.

Abstract: Leather can be pretreated to obtain good body, soft feel, and excellent grain smoothness and solidity with products having a molecular weight of 700 to 30,000 and which are obtainable by reaction ofA. polysuccinimide having a molecular weight, determined as the number-average, of 500 to 10,000, withB. 5 to 90 mol % based on the succinimide units of polysuccinimide A, and/or secondary amine, the nitrogen substituents of which contain 1 to 60 carbon atoms and which can be unsubstituted or substituted, at least 2.5 mol % of the nitrogen substituents of the amine containing at least 12 carbon atoms,C. optionally, (i) derivatives of C.sub.1 -C.sub.18 -monocarboxylic acids, C.sub.2 -C.sub.10 -dicarboxylic acids, and/or (ii) monoisocyanates, diisocyanates epichlorohydrin (for reaction of amino and/or hydroxyl groups on the nitrogen substituents of the reaction product of A and B), andD. 95 to 10 mol % of ring-opening base in the presence of water.