| abstract |
The hydrogels are based on polymerized monomers or on graft polymers and each have a Pressure Absorbency Index <100 and a vertical absorption of not less than 12 g/g under a pressure of 1922.8 Pa. They are produced by free-radically polymerizing hydrophilic monomers which contain acid groups, or their alkali metal or ammonium salts, with(a) a copolymerization crosslinker which contains at least two ethylenically unsaturated double bonds in the molecule, and(b) a reactive crosslinker A which contains an ethylenically unsaturated double bond and at least one functional group capable of forming covalent bonds with the acid groups of the hydrophilic polymers, a reactive crosslinker B which contains at least two functional groups capable of forming covalent bonds with the acid groups of the hydrophilic polymers, and/or with ions of polyvalent metalsoptionally in the presence of at least one grafting base to form a crosslinked, hydrophilic base polymer, comminuting said base polymer and postcrosslinking the surface of the particles of said base polymer, and are useful as absorbents for water and aqueous fluids. |