Patent ID: 8198385

Claim:
A continuous or batch process for the preparation of a super-absorbent polymer comprising the steps of: a) subjecting an aqueous monomer mixture containing at least one α,β-ethylenically unsaturated monomer; at least one monomer bearing at least two α,β-ethylenically unsaturated groups; iron ions in an amount of from about 0.1 to about 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 from about 0.8 to about 4.0 to free radical polymerization in an reactor to obtain a superabsorbent 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.