INITIATOR SYSTEM FOR PREPARATION OF A WATER-ABSORBENT POLYMER BY RADICAL POLYMERIZATION

摘要

The invention generally relates to a process for the preparation of water-absorbent polymer particles, comprising the process steps of (i) preparing an aqueous monomer solution comprising at least one partially neutralized, monoethylenically unsaturated monomer bearing carboxylic acid groups (α1) and at least one crosslinker (α3); (ii) optionally adding fine particles of a water-absorbent polymer to the aqueous monomer solution; (iii) adding a polymerization initiator system to the aqueous monomer solution; (iv) optionally decreasing the oxygen content of the aqueous monomer solution; (v) charging the aqueous monomer solution into a polymerization reactor; (vi) polymerizing the monomers; thereby obtaining a polymer gel; (vii) discharging the polymer gel out of the polymerization reactor and optionally comminuting the polymer gel; (viii) drying the optionally comminuted polymer gel; (ix) grinding the dried polymer gel thereby obtaining water-absorbent polymer particles; (x) sizing the grinded water-absorbent polymer particles; and (xi) surface-crosslinking the grinded and sized water-absorbent polymer particles; wherein in process step (iii) the polymerization initiator system comprises the fol-lowing initiator components iiia. a peroxodisulfate; and iiib. an organic initiator molecule comprising at least three oxygen atoms or at least three nitrogen atoms; wherein the polymerization initiator system comprises the peroxodisulfate and the organic initiator molecule in a molar ratio in the range of from 20:1 to 50:1.