WATER ABSORBING RESIN WITH IMPROVED INTERNAL STRUCTURE AND MANUFACTURING METHOD THEREFOR

摘要

According to the present invention, the manufacturing method for the water absorbing resin involves the step of polymerizing a water-soluble unsaturated monomer, 0.06 of 5 mol% of which is composed of an internal crosslinking agent; and the step of drying a water-containing gel which has a thermally decomposing radical initiator content index of 40 to 100 at 100 to 250°C. The water absorbing resin of the present invention contains a water-soluble unsaturated monomer as a repeat unit for a major chain, 90 mol% of the monomer being composed of an acrylic acid and/or salt thereof, the resin having an internal crosslinking structure and exhibiting a weight-average molecular weight Mw of 360, 000 to 1, 000, 000 daltons and an intrinsic viscosity IV of 2.1 to 6.0 dL/g where the weight-average molecular weight Mw and the intrinsic viscosity IV are measured after treatment under set 2 of hydrolysis conditions.