Process for producing a water-soluble polymer dispersion using a thickening agent

摘要

A process for the preparing dispersions of water-soluble polymers is claimed comprising: polymerizing a water-soluble monomer having a double bond in an aqueous salt solution that dissolves the monomer but does not dissolve the formed polymer while stirring in the presence of a dispersant to obtain fine polymer particles dispersed in the aqueous salt solution. At least one thickening inhibitor selected from among: (A) polyvalent carboxylic acids and salts thereof; (B) polyvalent phenols; (C) cyclic hydroxyl carboxylic acids and salts thereof; (D) gluconic acid and salts thereof; (E) products obtained by reacting methoxyhydroquinone and/or a (meth)acrylic cationic monomer with a compound generating free radicals in an oxidizing atmosphere; (F) products obtained by reacting a (meth)acrylic cationic polymer with a compound generating free radicals in an oxidizing atmosphere; (G) products obtained by reacting a (meth)acrylic cationic polymer with an oxidizing agent, and (H) mixtures of two or more of them is added to the reaction mixture during processing. The water-soluble monomer having double bonds are composed of 0-30% mol% of acrylic acid, 0-100% mol% of acrylamide and 0-100% mol% of cationic monomer as defined in the specification. The dispersant comprises a polymer electrolyte soluble in the aqueous salt solution.