Patent ID: 8875415

Claim:
A method for drying a particulate water-containing gel-like crosslinked polymer which comprises polymerizing acrylic acid or partially neutralized salt thereof with a crosslinking agent in an aqueous solution to obtain a particulate water-containing gel-like crosslinked polymer of a partially neutralized salt of polyacrylic acid containing acrylic acid or salt thereof as a main component and having a solid content concentration of 35% to 75% by weight, and drying the particulate water-containing gel-like crosslinked polymer with a through-circulation dryer using hot air having a temperature of 130 to 230° C. and a dew point of 50 to 80° C., wherein over 60% or more of a period from a time of introducing the particulate water-containing gel-like crosslinked polymer into a drying zone of the through-circulation dryer to a time of reaching a solid content concentration thereof to 80% by weight, a difference of temperature (ΔT) between a temperature of hot air blown to a particulate hydrogel layer and a temperature measured after the hot air passes through the particulate hydrogel layer is 20 to 70° C., wherein the temperature of the particulate water-containing gel-like crosslinked polymer immediately before being introduced into the drying zone is 40 to 70° C., and the dew point of the hot air used in the through-circulation dryer is varied in multiple stages.