Evonik Degussa Gmbh

Evonik Stockhausen Gmbh

Evonik Industries Ag

Harald Plochinger

Marc Hager

Herbert A Gartner

Hans-Peter Kohler

Daniel Fricker

Jorg Harren

Sabine Auernig

Elisabeth Lacker

Richard Walther

The present invention relates to a method for heat-treating water-absorbing polymeric particles at a temperature equal to or above 150&#xb0; C. in a fluidized bed dryer at a fast heat-up rate, the use of a fluidized bed dryer for heat-treating water-absorbing polymeric particles in continuous or batch mode as well as to the heat-treated polymeric particles obtained by the method of the present invention.

Heat-treatment of water-absorbing polymeric particles in a fluidized bed at a fast heat-up rate

The invention relates generally to a process for the preparation of water-absorbent polymer particles, including the process steps of preparing particulate water-absorbent polymer and mixing the particulate water-absorbent polymer with an aqueous crosslinker solution and heat-treating the mixture of particulate water-absorbent polymer in a horizontally operated mixing device, wherein the horizontally operated mixing device is hydraulically driven. The invention also relates to water-absorbent polymer particles obtainable by such a process.

Process for the continuous preparation of water-absorbent polymers

The present invention relates to a continuous process for the production of a superabsorbent polymer comprising providing an acidic liquid aqueous monomer mixture containing dissolved oxygen; continuously feeding the aqueous monomer mixture to a reactor; introducing a source of carbonate or hydrogen carbonate into the aqueous monomer mixture prior to entry into the reactor thereby forming a gas phase comprising carbon dioxide and at least a part of the dissolved oxygen, the gas phase being dispersed in the liquid phase; subjecting the gas/liquid mixture to at least partial phase separation immediately prior to or after entry into the reactor and at least partially removing the separated gaseous phase; subjecting the liquid phase in the reactor to free-radical polymerization to obtain the superabsorbent polymer, and continuously removing the superabsorbent polymer from the reactor.

Superabsorbent polymer process

The present invention relates to superabsorbent polymer comprising the comprising the free radical polymerization product of an aqueous monomer mixture containing at least one &#x3b1;,&#x3b2;-ethylenically unsaturated monomer; at least one monomer having at least two &#x3b1;,&#x3b2;-ethylenically unsaturated groups; a crosslinking agent having at least two polymerizable double bonds; iron ions in an amount of from about 0.1 to about 3 wppm based on the total weight of the aqueous monomer mixture; and at least one chelating agent in an amount to provide a molar ratio of chelating agent to iron ion of from about 0.8 to about 4.0.

Process for the production of a superabsorbent polymer

The present invention relates to process for the preparation of a superabsorbent polymer comprising the steps of a) subjecting an aqueous monomer mixture containing at least one &#x3b1;,&#x3b2;-ethylenically unsaturated monomer; at least one monomer bearing at least two &#x3b1;,&#x3b2;-ethylenically unsaturated groups; iron ions in an amount of 0.1 to 3 wppm based on the total weight of the aqueous monomer mixture; and at least one chelating agent in an amount to provide a mol ratio of chelating agent to iron ion of 0.8 to 4.0 to free radical polymerization in an reactor to obtain a super-absorbent polymer; and b) recovering the superabsorbent polymer, whereby if the process is continuous and is run in an agitated reactor the upper limit of the mol ratio of chelating agent to iron ion is 4.0 for a throughput of total reaction mixture through the reactor of at most 1.3 kg/h per liter reactor volume.

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Buhl, Germany

Harald Plochinger