METHOD FOR PRODUCING WATER ABSORBENT RESIN POWDER

摘要

Disclosed is a method for producing a water absorbent resin on a large scale, by which physical properties of the water absorbent resin such as damage resistance and water absorption rate are improved and stabilized by simple procedures without requiring change in the starting materials or large equipment investment. Specifically, in a pulverization step preceding a surface crosslinking step, the water absorbent resin is circulated in a predetermined amount or more. In other words, before the surface crosslinking step, at least some of classified polymers are re-fed to the same or another pulverization step, and the circulation-pulverization ratio (that is defined by the formula below) is set at 1.10-1.50 at this time. (circulation-pulverization ratio) = (total amount of water absorbent resin supplied to pulverization step)/(total amount of water absorbent resin discharged from drying step) (In this connection, (total amount of water absorbent resin supplied to pulverization step) = (total amount of water absorbent resin discharged from drying step) + (amount of classified polymers re-fed to the same or another pulverization step))