Evonik Degussa Gmbh

Dominik Gartz

Laurent Wattebled

Jorg Harren

Jörg Harren

Christoph Loick

Ingo Loy

Described is the production of water-absorbing polymeric particles by polymerizing a monomer solution or suspension comprising a) at least one ethylenically unsaturated acid-functional monomer which is optionally at least partly present as salt, b) at least one crosslinker and c) at least one initiator, wherein the process further comprises drying the resulting polymer and also optionally grinding the dried polymer and sieving the ground polymer and also optionally surface-postcrosslinking the dried and possibly ground and sieved polymer, and wherein the polymerization is carried out in the presence of aminopolycarboxylic acids and/or salts thereof, in particular in the presence of ethylenediaminedisuccinic acid and/or a salt thereof.

Aminopolycarboxylic acids useful as processing aids in the manufacture of superabsorbents

A process for producing a water-absorbing polymer comprises: (i) mixing (&#x3b1;1) 0.1-99.99% by weight of ethylenically unsaturated monomers containing acid groups or salts thereof, or ethylenically unsaturated monomers including a protonated or quaternized nitrogen, or mixtures thereof, (&#x3b1;2) 0-70% by weight of ethylenically unsaturated monomers copolymerizable with (&#x3b1;1), (&#x3b1;3) 0.001-10% by weight of one or more crosslinkers, (&#x3b1;4) 0-30% by weight of water-soluble polymers, and (&#x3b1;5) 0-20% by weight of one or more assistants, where the sum of the weights (&#x3b1;1) to (&#x3b1;5) is 100%; (ii) free-radical polymerization with crosslinking to form an untreated hydrogel polymer; (iii) coarse comminution of the untreated hydrogel polymer to give pieces having a diameter from 0.1 mm to 5.0 cm; (iv) cooling and grinding the untreated hydrogel polymer; (v) drying the untreated hydrogel polymer after grinding at a temperature from 85&#xb0; C. to 260&#xb0; C.; (vi) postcrosslinking the hydrogel polymer and (vii) drying the water-absorbing polymer.

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Viersen, Germany

Dominik Gartz