Patent ID: 8349946

Claim:
A process for producing a water-absorbing resin by polymerization of a reaction mixture comprising at least one hydrophilic monomer and, optionally, at least one crosslinker in a reactor, which comprises admixing the reaction mixture with at least one first portion of a particulate additive before a reaction mixture has reached a residence time of 40% of the overall residence time in the reactor and with at least one second portion of a particulate additive when the reaction mixture has reached a residence time of 45% or more of the overall residence time in the reactor, the additive being selected from the group consisting of water-absorbing resin powders, fillers, and mixtures thereof, a total solids content of monomer and additive being in the range from 30% to 60% by weight, an amount of additive being in the range from 5% to 50% by weight, based on the monomers, and a weight ratio of the first portion to the second portion of the additive being in the range from 10:1 to 1:5.