| abstract |
Superabsorbents comprising a compound of the formula (I) n n n n n n n n n n in whichn M is a hydrogen atom, an ammonium ion, a monovalent metal ion or one equivalent of a divalent metal ion of groups 1, 2, 8, 9, 10, 12 or 14 of the periodic table of the elements; R 1 is OH or NR 4 R 5 where R 4 and R 5 are each independently H or C 1 -C 6 -alkyl; R 2 is H or an alkyl, alkenyl, cycloalkyl or aryl group, where this group optionally has 1, 2 or 3 substituents which are each independently selected from C 1 -C 6 -alkyl, OH, O—C 1 -C 6 -alkyl, halogen and CF 3 ; and R 3 is COOM, SO 3 M, COR 4 , CONR 4 R 5 or COOR 4 , where M, R 4 and R 5 are each as defined above or, when R 2 is aryl which is optionally substituted as specified above, are also H,n nsalts thereof or mixtures of such compounds and/or salts thereof,n exhibit improved stability to discoloration in the course of storage under elevated temperatures and/or elevated air humidity. |