METHOD FOR PRODUCING PREPOLYMER

摘要

PROBLEM TO BE SOLVED: To provide a prepolymer easy to handle, having excellent processability and usable as a precursor of a water-absorbing resin in the production of a water-absorbing resin composite material represented by paper diaper and sanitary napkin. SOLUTION: The prepolymer for a water-absorbing resin can be produced by irradiating an aqueous solution of a water-soluble monomer composed mainly of acrylic acid and/or an acrylic acid salt with ultraviolet rays to partly polymerize the water-soluble monomer.