| 主权项 |
1. A process for producing water-absorbent polymer particles by polymerizing droplets of
a) at least one ethylenically unsaturated monomer which bears an acid group and optionally is at least partly neutralized, b) at least one crosslinker, c1) less than 0.3% by weight, based on monomer a), of at least one persulfate, c2) at least 0.05% by weight, based on monomer a), of at least one azo initiator, d) optionally one or more ethylenically unsaturated monomer copolymerizable with the monomer mentioned under a), e) optionally one or more water-soluble polymer, and f) water, in a surrounding heated gas phase in a reaction zone and thermal posttreatment in a fluidized bed, wherein a temperature of a gas leaving the reaction zone is less than 150° C., a temperature of the water-absorbent polymer particles during the thermal posttreatment is less than 100° C., and a residence time of the water-absorbent polymer particles in the fluidized bed is from 60 to 300 minutes. |
