Process for producing high-swellability polymer composites

A process for producing polymer composites suitable for absorbing and storing aqueous liquids, comprising:

• a free-radical polymerization of a monomer composition M which comprises
• a) 50 to 100% by weight, based on the total amount of monomers A and B, of at least one monomer A having one ethylenic double bond and at least one neutralizable acid group,
• b) 0 to 50% by weight of optionally one or more comonomers B which are different than the monomers A and have one ethylenic double bond, and
• c) 0 to 10% by weight, based on the total amount of monomers A and B, of at least one crosslinker C,
• in an aqueous suspension of a water-insoluble particulate substance S comprising cellulose or lignocellulose, the weight ratio of the monomer composition M to the substance S being in the range from 9:1 to 1:9;
• wherein the monomers A used for polymerization are present in the aqueous suspension in anionic form to an extent of at least 10 mol %;
• and
• wherein the aqueous suspension contains urea during the polymerization.