CATIONIC SIZING AGENTS FOR PAPER

Cationic sizing agents for paper A b s t r a c t Cationic sizing agents for paper, obtainable by a process in which a water-soluble cationic terpolymer compound, built up in a chemically uniform manner, of a) 7 to 40% by weight of N,N-dimethylaminoethyl acrylate and/or methacrylate, b) 40 to 80% by weight of styrene and c) 4 to 50% by weight of acrylonitrile, the sum of components a) to c) always being 100% by weight and at least 10% of the dimethylamino groups of the terpolymer being quaternized with monoepoxides, with the exception of epihalogenohydrins, and the remainder being protonated, is dissolved in an aqueous medium and, in the presence of 10 to 70% by weight - based on the following monomer mixture of this emulsifier, d) 5 to 95% by weight of acrylonitrile, meth-acrylonitrile or styrene or mixtures thereof and e) 5 to 95% by weight of acrylic acid ester and/or methacrylic acid ester with 1 to 12 C atoms in the alcohol radical -the sum of components d) and e) always being 100% by weight are emulsified and the emulsion thus obtained is subjected to emulsion polymerization, initiated by free radicals, at temperatures of 20 to 150.degree.C.