Color-stable superabsorber

摘要

A superabsorbent produced by polymerizing a monomer mixture which comprises at least one ethylenically unsaturated monomer bearing at least one acid group, at least 0.1% by weight and at most 20% by weight, based on the total amount of ethylenically unsaturated monomers bearing at least one acid group (calculated as the free acid), of at least one alkaline earth metal salt (calculated without water of crystallization) selected from the salts of calcium, strontium or barium having been added before or during the polymerization and/or, if the polymerization is followed by a separate drying step, to the polymer before the drying, exhibits improved stability to discoloration in the course of storage under elevated temperatures and/or elevated air humidity.

主权项

1. A superabsorbent produced by polymerizing a monomer mixture comprising (a) at least one ethylenically unsaturated monomer bearing at least one acid group neutralized from 25 to 95 mol % as an alkali metal or ammonium salt and (b) at least 1% by weight and at most 5%, by weight, of at least one alkaline earth metal salt (calculated without water of crystallization) based on the total amount of ethylenically unsaturated monomer bearing at least one acid group (calculated as the free acid), the at least one alkaline earth metal salt selected from the salts of calcium, strontium, and barium, and the at least one alkaline earth metal salt having been added after neutralization of the monomer and during the polymerization and/or, if the polymerization is followed by a separate drying step, to the polymer before the drying.