FINE-PARTICLE, CATIONIC POLYMER DISPERSIONS

摘要

The invention relates to fine-particle, cationic polymer dispersions that can be obtained by emulsion polymerisation of ethylenically unsaturated monomers in an aqueous solution of a cationic pre-polymer as a dispersant. First, a cationic pre-polymer is produced by the polymerisation of: a) between 10 and 45 wt. % of at least one (meth)acrylic acid ester comprising an amino group and/or a quarternary ammonium group, and/or a (meth)acrylic amide, carrying an amino group and/or a quaternary ammonium group, b) between 40 and 85 wt. % of at least one optionally substituted styrol, c) between 0 and 20 wt. % of acrylic nitrile or methacrylic nitrile, d) between 1 and 15 wt. % of at least one ethylenically unsaturated carboxylic acid or an ethylenically unsaturated carboxylic acid anhydride, and e) between 0 and 20 wt. % of at least one non-ionic, ethylenically unsaturated monomer different from the monomers (b) and (c), the sum of (a) + (b) + (c) + (d) + (e) amounting to 100 wt. %, in a solution polymerisation in an organic solvent that can be mixed with water. The solution of the pre-polymer produced in this way is diluted with water, and then an emulsion polymerisation of a monomer mixture of: i) between 30 and 80 wt. % of acrylic nitrile and/or methacrylic nitrile, ii) between 5 and 50 wt. % of at least one C₁ to C₄ alkyl acrylate or at least one C₁ to C₄ alkyl methacrylate, iii) between 5 and 50 wt. % of at least one C₆ to C₁₄ alkyl acrylate or at least one C₆ to C₁₄ alkyl methacrylate, and iv) between 0 and 20 wt. % of a non-ionic monomer diferent from the monomers (i), (ii) und (iii), the sum of (i) + (ii) + (iii) + (iv) amounting to 100 wt. %, is carried out in the aqueous solution of the pre-polymer, in the presence of water-soluble polymerisation inhibitors. The invention also relates to the use of the fine-particle cationic polymer dispersions obtained in this way as materials and surface sizing agents for paper, paperboard and cardboard.