SURFACE TREATMENT METHOD OF WATER-ABSORBING RESIN AND PRODUCTION METHOD OF WATER-ABSORBING RESIN

摘要

Provided is a method for producing a superior surface-crosslinked water-absorbing resin with stable properties based on the discovery of appropriate conditions for pre-treatment in the surface treatment of a water-absorbing resin. The surface treatment of a water-absorbing resin includes the following three processes: 1) a wet mixing process wherein a base polymer and a surface crosslinking agent solution are mixed together to form a 'wet mixture'; 2) a pre-treatment process wherein the temperature of said wet mixture is raised and 'pre-treated material' is obtained; and 3) a surface crosslinking reaction surface-crosslinked process wherein said pre-treated material is subjected to a crosslinking reaction and a 'water-absorbing resin' is obtained. The dew point of the atmosphere in the pre-treatment process 2) is from 50 to 95°C and the temperature of said wet material is raised from a temperature below said dew point to the dew point + 10°C.