Process for water-soluble synthetic polymer in powder form

Claim 1

A process for preparing a high molecular weight water-soluble synthetic polymer in the form of a readily dissolved powder which process comprises: (1) preparing an aqueous monomer solution comprising water, from about 20 to 50 weight percent of a water-soluble ethylenically unsaturated monomer providing a water-soluble polymer, based on the total weight of water and monomer, and from about 100 to 2,000 parts per million based on the total weight of said monomer solution of a free radical initiator; (2) separately preparing an aqueous redox initiator system; (3) mixing said redox system with said monomer solution while introducing said monomer solution into an advancing polymerization zone; (4) maintaining said monomer solution in said polymerization zone at suitable temperature to provide an aqueous polymer gel; (5) removing said polymer gel from said polymerization zone; (6) granulating said polymer gel; (7) partially drying said polymer gel to provide a cake having about 25 to 45 weight percent water; (8) breaking the partially dried polymer cake to provide granules; (9) further drying the granules to reduce the water content to less than about 15 weight percent; and (10) pulverizing the thus-dried polymer.