Low-foam surface sizing agents for paper which contain copolymeric maleic anhydride semi-amides

摘要

Low-foam surface sizing agents for paper in the form of aqueous or aqueous-alcoholic alkali metal, amine or ammonium salt solutions of copolymers containing carboxylic acid semi-amide groups obtainable by reacting copolymers of maleic acid anhydride and diisobutylene and/or terpolymers of maleic acid anhydride, diisobutylene and a vinyl monomer copolymerizing with maleic acid anhydride, with from 5 to 50 mole percent, based on maleic acid anhydride groups, of a primary aliphatic or aromatic monoamine. The solutions may optionally contain urea or derivatives of urea.