Pulverulent, cross-linked polymers capable of absorbing aqueous liquids

Pulverulent polymer which absorbs water, aqueous or serous liquids as well as blood, which is post-cross-linked on the surface and is synthesized from

• a) from 55 to 99.9 wt. % polymerized, ethylenically unsaturated, acid group-containing monomers which are at least 25 mol % neutralised,
• b) from 0 to 40 wt. % polymerised, ethylenically unsaturated monomers which are copolymerisable with a),
• c) from 0.1 to 5.0 wt. % of one or more polymerized cross-linking agents,
• d) from 0 to 30 wt. % of a water-soluble polymer,
• wherein the sum of the quantities by weight a) to d) is 100 wt. %, wherein the polymer is coated and post-cross-linked, with heating, with
• e) from 0.01 to 5 wt. %, in relation to the polymer, of an organic surface post-cross-linking agent, with the exception of polyols, in the form of an aqueous solution and with
• f) from 0.001 to 1.0 wt. %, in relation to the polymer, of a cation in the form of a salt dissolved in an aqueous solution,
• wherein the total quantity of water of the coating solution is from 0.5 to 10 wt. %, in relation to the polymer, and the ratio by weight of the salt to the post-cross-linking agent is within the range 1:0.8 to 1:4, and wherein
• cross-linked polyacrylic acids which are up to 70 mol % present as Na salts and which have been surface post-cross-linked with an aqueous solution containing Al2(SO4)3.18 H2O and 1,3-dioxolan-2-one in a ratio by weight of from 1:2 or with Al2(SO4)3.14 H2O and 1,3-dioxolan-2-one in a ratio by weight of 1:2 or with Al2(SO4)3.18 H2O and ethylene glycol diglycidyl ether in a ratio by weight of 1:1 or with aluminium chloride.6 H2O and 1,3-dioxolan-2-one in a ratio by weight of 1:1.43 or with iron(III) chloride.6 H2O and 1,3-dioxolan-2-one in a ratio by weight of 1:1.43 or Ca acetate.hydrate or Mg acetate.hydrate and 1,3-dioxolan-2-one in a ratio by weight of 1:10,
• or cross-linked polyacrylic acid which is 70 mol % present as Na salt and which is grafted on native waxy maize starch or polyvinyl alcohol and has been coated and surface post-cross-linked with an aqueous solution containing Al2(SO4)3.14 H2O and 1,3-dioxolan-2-one in a ratio by weight of 1:2, are excepted.