Process for preparing water-soluble polymer gel particles

A process for preparing dry, spherical, polymer gel, powder particles from an aqueous polymer gel in a wet state obtained by subjecting an aqueous solution of a water-soluble vinyl monomer to polymerization which comprises feeding said polymer gel in a wet state into a roller cutter including a pair of cutter rollers wherein the rollers bite into said polymer gel with a plurality of annular projections or grooves at predetermined intervals on surfaces of the rollers, said rollers rotating in the opposite directions to each other to engage with each other, thereby cutting the polymer gel into strips;

• thereafter cutting said strips in a wet state into pieces by a combination of a fixed cutting blade with a rotary cutter, said fixed cutting blade extending in the axial direction of said roller cutter over at least the full length of said roller cutter and said rotary cutter including a rotatable cylindrical body provided on its periphery with at least one cutting blade extending in the axial direction;
• pulverizing the obtained pieces of polymer gel in a wet state into fine, round particles with a vertical type cutter comprising a casing, at least one vertically fixed cutting blade arranged in said casing in a vertical direction, at least one rotary cutting blade arranged rotatably and vertically in said casing and positioned to minimize the clearance between an edge of the rotary cutting blade and an edge of the fixed cutting blade, said vertical type cutter having a residence space wherein the polymer gel pieces to be pulverized are located, and the residence time of the polymer gel pieces in said residence space being at least 3 minutes;
• and drying said fine, round particles.