Patent ID: 8497337

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 acid groups and optionally is 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 monomers mentioned under a); and e) optionally one or more water-soluble polymers, comprising the steps of 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 aliphatic aldehyde or reaction product thereof with an aliphatic alcohol, an aliphatic amine, ammonia, a hypophosphite, or a phosphite before, during or after one of steps i) to v), wherein the aliphatic aldehyde or reaction product thereof with an aliphatic alcohol, an aliphatic amine, ammonia, a hypophosphite, or a phosphite is selected from the group consisting of formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, glycolaldehyde, glyceraldehyde, a formaldehyde acetal, an acetaldehyde acetal, a propionaldehyde acetal, a butyraldehyde acetal, a glycolaldehyde acetal, a glyceraldehyde acetal, sodium glyoxylate, potassium glyoxylate, 2,5-dihydroxy-1,4-dioxane, 3,6-dihydroxy-2,5-dihydroxymethyl-1,4-dioxane, sodium 2,2-dimethoxyacetate, potassium 2,2-dimethoxyacetate, sodium 2,2-diethoxyacetate, potassium 2,2-diethoxyacetate, hexamethylenetetramine, an azomethine, an enamine, an aminal, 2-hydroxy-2-phosphonoacetic acid, and 2-hydroxy-2-phosphonoacetic acid.