Process for preparing water-absorbing resin

A process for preparing a cross-linked or partially cross-linked water-absorbing resin which comprises the steps of mixing powder of an inorganic inactive substance with a water-absorbing resin being the polymerization product of carboxylate-containing monomer units, and adding water in an amount of about 5 to about 100% by weight based on the solid weight of the starting water-absorbing resin and a cross-linking agent in an amount of at least 0.1 part by weight per 100 parts by weight of the starting water-absorbing resin to the mixture to perform cross-linking reaction and evaporation of the water, the water-absorbing resin containing a functional group reactive with the cross-linking agent and the cross-linking agent containing at least two functional groups reactive with the functional group of the water-absorbing resin and being at least one species selected from:

• (1) a copolymer comprising about 3 to about 40 mole % of glycidyl acrylate or glycidyl methacrylate (component A), about 3 to about 50 mole % of dialkylaminoalkyl acrylate or dialkylaminoalkyl methacrylate and/or dialkylaminoalkyl acrylamide or dialkylaminoalkyl methacrylamide (component B), about 20 to about 90 mole % of an unsaturated hydrophilic monomer copolymerizable with the components A and B and not containing any carboxyl group (component C), and 0 to about 60 mole % of an unsaturated hydrophilic monomer copolymerizable with the components A, B and C and
• (2) a mixture of a copolymer comprising about 3 to about 40 mole % of the component A, about 10 to about 97 mole % of the component C and 0 to about 50 mole % of the component D with a copolymer comprising about 3 to about 50 mole % of the component B, about 10 to about 97 mole % of the component C and 0 to about 50 mole % of the component D.