Abstract: Carboxyl group-containing polymer particles giving a neutralized viscous liquid being excellent in gel appearance and transparency. Carboxyl group-containing polymer particles comprising 55 to 94% by volume of water-swelled gel particles having a particle diameter of less than 50 ?m when the carboxyl group-containing polymer particles are dispersed and swelled in water in a concentration of 0.5% by weight, and 6 to 45% by volume of water-swelled gel particles having a particle diameter of at least 50 ?m when carboxyl group-containing polymer gel particles are dispersed and swelled in water in a concentration of 0.5% by weight.

Abstract: A process for preparing a water-soluble carboxyl group-containing polymer comprising reacting an ?,?-unsaturated carboxylic acid with a compound having at least two ethylenically unsaturated groups in an inert solvent in the presence of a radical polymerization initiator, the process for preparing a water-soluble carboxyl group-containing polymer being characterized in that the ?,?-unsaturated carboxylic acid is further added to a reaction mixture in which 20 to 70% by mol of an unreacted ?,?-unsaturated carboxylic acid remains, and the ?,?-unsaturated carboxylic acid is reacted with the compound having at least two ethylenically unsaturated groups; and a water-soluble carboxyl group-containing polymer obtainable by the above-mentioned process, wherein the reducing ratio of viscosity of a 0.2% by weight neutralized viscous liquid is less than 25%, and the equilibrium viscosity of the neutralized viscous liquid is 20000 to 50000 mPa.s.

Abstract: A carboxyl group-containing polymer composition comprising 100 parts by weight of a carboxyl group-containing polymer (A) prepared by copolymerizing an ?,?-unsaturated carboxylic acid (a) with a compound (b) having at least two ethylenic unsaturated groups; and 0.01 to 20 parts by weight of at least one compound (B) selected from an ester (c) obtained from a polyhydric alcohol and a fatty acid, and an alkylene oxide adduct of an ester (d) obtained from a polyhydric alcohol and a fatty acid. Since the carboxyl group-containing polymer composition is excellent in the solubility in water and gives the aqueous solution excellent thickening property, the polymer composition can be suitably used as a thickener for various aqueous solutions.

Abstract: Carboxyl group-containing polymer particles giving a neutralized viscous liquid being excellent in gel appearance and transparency. Carboxyl group-containing polymer particles comprising 55 to 94% by volume of water-swelled gel particles having a particle diameter of less than 50 &mgr;m when the carboxyl group-containing polymer particles are dispersed and swelled in water in a concentration of 0.5% by weight, and 6 to 45% by volume of water-swelled gel particles having a particle diameter of at least 50 &mgr;m when carboxyl group-containing polymer gel particles are dispersed and swelled in water in a concentration of 0.5% by weight.