Patent ID: 8633285

Claim:
A process for producing water-absorbing polymer particles by polymerizing an aqueous monomer solution or suspension comprising a) at least one ethylenically unsaturated monomer which bears acid groups and may be at least partly neutralized, b) at least one crosslinker, c) optionally one or more ethylenically and/or allylically unsaturated monomer copolymerizable with the monomer mentioned under a), and d) optionally one or more water-soluble polymers, comprising i) solution polymerization in a polymerization reactor to obtain a polymer, gel in the polymerization reactor, ii) addition of at least one solid additive during and/or after the solution polymerization to the polymer gel by means of at least one conveying screw ( 1 ), the solid additive being fed to the conveying screw ( 1 ) by means of an addition channel ( 2 ), and iii) mixing the solid additive into the polymer gel, wherein a gas volume flow is additionally fed via the addition channel ( 2 ) to the conveying screw ( 1 ), such that a gas velocity of the gas volume flow in the addition channel ( 2 ) in a direction of the conveying screw ( 1 ) is at least 0.05 m/s and a dew point of the gas volume flow is at least 20° C. below the lowest inner wall temperature of the conveying screw ( 1 ) and the addition channel ( 2 ), and wherein the conveying screw ( 1 ) and the addition channel ( 2 ) are thermally insulated and/or trace-heated.