Patent ID: 9737874
Date: 2017-08-22
CPC Classifications: A61L,B01J,C08F,C08J

Claim:
1. A process for producing a water-absorbing polymer composition, comprising the process steps of (i) forming an aqueous monomer solution by mixing (ii) free-radical polymerization with crosslinking to form a water-insoluble aqueous untreated hydrogel polymer, (iii) drying the hydrogel polymer, (iv) grinding and sieving the water-absorbing polymer, (v) surface postcrosslinking the ground hydrogel polymer of step (iv), and (vi) drying and finishing the water-absorbing polymer, wherein the process in steps i) and ii) is done in a kneading reactor having at least one shaft and not through a reactor employing a poly belt, and wherein granulated blowing agents consisting of soda carbonate particles having a particle size of 100 μm to 900 μm are added to the aqueous monomer solution of part (i) prior to the addition of an initiator and the start of the free-radical polymerization, and wherein the water-absorbing polymer composition has a FSR is in the range from 0.4 to 0.55.