Patent ID: 8859701

Claim:
A process for producing a water-absorbing polymer comprising: (i) mixing (α1) 0.1 to 99.99% by weight ethylenically unsaturated monomers containing acid groups or salts thereof, or ethylenically unsaturated monomers including a protonated or quaternized nitrogen, or mixtures thereof, (α2) 0 to 70% by weight ethylenically unsaturated monomers copolymerizable with (α1), (α3) 0.001 to 10% by weight of one or more crosslinkers, (α4) 0 to 30% by weight of water-soluble polymers, and (α5) 0 to 20% by weight of one or more assistants, where the sum of the weights (α1) to (α5) is 100% by weight; (ii) free-radical polymerization with crosslinking to form a water-insoluble aqueous untreated hydrogel polymer; (iii) coarse comminution of the untreated hydrogel polymer to give pieces having a diameter in the range from 0.1 mm to 5.0 cm; (iv) cooling the coarsely comminuted untreated hydrogel polymer and grinding the cooled untreated hydrogen polymer; (v) drying the comminuted untreated hydrogel polymer after grinding at a temperature in the range from 85° C. to 260° C., and sieving the dried pieces in the range from 150 μm to 850 μm; (vi) postcrosslinking the hydrogel polymer and (vii) drying and finishing the water-absorbing polymer, wherein the cooling is carried out at a temperature of −30° C. to −200° C.