A PROCESS FOR THE PRODUCTION OF A SUPERABSORBENT POLYMER

The present invention relates to a continuous or batch process for the preparation of a super-absorbent polymer comprising: a) subjecting an aqueous monomer mixture containing - at least one ±,²-ethylenically unsaturated monomer; - at least one monomer bearing at least two ±,²-ethylenically unsaturated groups; - iron ions in an amount of 0.1 to 3 wppm based on the total weight of the aqueous monomer mixture; and - at least one chelating agent in an amount to provide a mol ratio of chelating agent to iron ion of 0.8 to 4.0 to free radical polymerization in an reactor to obtain a super-absorbent polymer; and b) recovering the super-absorbent polymer, whereby if the process is continuous and is run in an agitated reactor the upper limit of the mol ratio of chelating agent to iron ion is - 4.0 for a throughput of total reaction mixture through the reactor of at most 1.3 kg/h per liter reactor volume, - 3.5 for a throughput of total reaction mixture through the reactor of more than 1.3 kg/h per liter reactor volume at most 2.5 kg/h per liter reactor volume, and - 1.5 for a throughput of total reaction mixture through the reactor of more than 2.5 kg/h per liter reactor volume.