Process for producing surface-postcrosslinked water-absorbent polymer particles
AssigneeBASF SE
InventorsThomas Daniel, Norbert Herfert, Stephan Bauer, Katrin Baumann, Birgit Reinhard, Jürgen Freiberg, Christophe Bauduin, Katarzyna Dobrosielska-Oura, Michael A. Mitchell
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Abstract
The present invention relates to a process for producing surface-postcrosslinked water-absorbent polymer particles by coating of water-absorbent polymer particles having a content of residual monomers in the range from 0.03 to 15% by weight with at least one surface-postcrosslinker and thermal surface-postcrosslinking at temperatures in the range from 100 to 180° C.
Claims17
A process for producing surface-postcrosslinked water-absorbent polymer particles, comprising forming water-absorbent polymer particles by polymerizing a monomer solution, comprising
- a) at least one ethylenically unsaturated monomer which bears an acid group and may be at least partly neutralized,
- b) optionally one or more crosslinker,
- c) at least one 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,
- coating the water-absorbent polymer particles with at least one surface-postcrosslinker, and thermal surface-postcrosslinking the coated water-absorbent polymer particles, wherein a content of residual monomers in the water-absorbent polymer particles prior to the coating with the surface-postcrosslinker is in the range from 0.1 to 15% by weight, and a temperature during the thermal surface-postcrosslinking is in the range from 100 to 180° C. wherein the surface-postcrosslinked water-absorbent polymer particles have a centrifuge retention capacity from 35 to 75 g/g.
Dependencies are inferred from the claim text.