Patent ID: 8703876

Claim:
A process for producing water-absorbing polymer particles by polymerizing a monomer solution or suspension comprising a) at least one ethylenically unsaturated monomer which bears an acid group and may be at least partly neutralized, b) at least one crosslinker, c) at least one initiator, d) optionally one or more ethylenically unsaturated monomer copolymerizable with the monomer mentioned under a) and e) optionally one or more water-soluble polymer, comprising polymerizing the monomer solution or suspension to give a polymer gel i), optionally comminuting the resulting polymer gel ii), drying the polymer gel iii), grinding and classifying the dried polymer gel to polymer particles iv), and optionally thermally surface postcrosslinking the classified polymer particles v), which comprises adding, at least one of hypophosphorous acid and phosphorous acid and salt thereof after step i) and before, during, or after one of step ii) to v), and at least one organic 2-hydroxy acid selected from the group consisting of 2-hydroxy-2-sulfonatoacetic acid, a 2-hydroxy-2-phosphonoacetic acid, and hydroxyethylidene-1,1′-diphosphonic acid and a salt thereof before step i), where the at least one of hypophosphorous acid and phosphorous acid and salt thereof is present in a vicinity of the water-absorbing particle surface.