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.
Claims12
Surface-postcrosslinked water-absorbent polymer particles having a centrifuge retention capacity from 40 to 55 g/g, an absorption under high load from 25 to 35 g/g, a level of extractable constituents of less than 10% by weight, and a porosity from 20 to 40%.
Surface-postcrosslinked water-absorbent polymer particles having a total liquid uptake of
- Y>−485×ln(X)+1865
- wherein Y (g) is the total liquid uptake and X (g/g) is the centrifuge retention capacity, wherein the centrifuge retention capacity is at least 25 g/g and the liquid uptake is at least 30 g.
Surface-postcrosslinked water-absorbent polymer particles having a change of characteristic swelling time of less than 0.6 and a centrifuge retention capacity of at least 35 g/g, wherein the change of characteristic swelling time is
- Z=(τ0.5−τ0.1)/τ0.5
- wherein Z is the change of characteristic swelling time, τ0.1 is the characteristic swelling time under a pressure of 0.1 psi (6.9 g/cm2) and τ0.5 is the characteristic swelling time under a pressure of 0.5 psi (35.0 g/cm2).
Dependencies are inferred from the claim text.