Basf Se Corporation

Roland Krauss

Volker Klock

Monica Haag

Stephan Deuerlein

Thomas Gieger

Holger Barthel

Matthias Weismantel

Markus Braun

Markus Albert Braun

Monika Haag

A single-screw extruder for changing a morphology of superabsorbent polymer gel. The single-screw extruder has an input aperture, a channel, a screw and an output aperture. The screw in the invention has a first pitch value of a pitch of the screw flights along the conveying zone of the channel and, following in conveying direction, has a second pitch value of the pitch of the screw flights along the conveying zone of the channel, where the second pitch value is smaller than the first pitch value.

Single-shaft extruder and use of a single-shaft extruder, and method for altering morphology of a superabsorbent polymer, specifically an SAP polymer gel, using a single-shaft extruder

A single-screw extruder for changing a morphology of a superabsorbent polymer, specifically a polymer gel. The single-screw extruder has an input aperture, a channel, a screw and an output aperture. The screw has a pitch value of a pitch of the screw flights along the conveying zone of the channel, where the channel has a mixing-element arrangement with at least one mixing element which protrudes into the channel of the single-screw extruder and which is configured for the mixing of the SAP polymer gel.

Single-shaft extruder and use of a single-shaft extruder, and method for altering morphology of a superabsorbent polymer gel using a single-shaft extruder

A process for producing water-absorbing polymer particles is provided, comprising a) a polymerization step in which an aqueous monomer solution comprising at least one ethylenically unsaturated monomer M which bears acid groups and may have been at least partly neutralized and at least one crosslinker is polymerized to obtain an aqueous polymer gel; b) a pelletization step in which the aqueous polymer gel having a solids content of 35 to 70% by weight and a temperature of 75 to 125&#xb0; C. is forced from a high-pressure zone through a die plate into a low-pressure zone and pellets are obtained, the pressure differential between the high-pressure zone and the low-pressure zone being 4 to less than 14 bar and the orifice ratio of the die plate being 30 to 80%; c) a drying step in which the pellets are dried to a moisture content of less than 10% by weight; d) a grinding step and a classifying step to obtain water-absorbing polymer particles; and e) surface crosslinking of the water-absorbing polymer particles. The water-absorbing polymer particles have a high swell rate and a high retention capacity combined with a favorable ratio of permeability of the swollen gel bed SFC to centrifuge retention capacity CRC.

Method for producing water-absorbing polymer particles

A process for producing water-absorbing polymer particles having high free swell rate and high centrifuge retention capacity with simultaneously high permeability of the swollen gel bed by polymerization of an aqueous monomer solution in a polymerization reactor having at least two shafts (kneaders) which rotate in an axially parallel manner, subsequent extrusion at high temperatures and thermal surface postcrosslinking.

Method for producing water-absorbing polymer particles with high swelling rate and high centrifuge retention capacity with simultaneously high permeability of the swollen gel bed

A process for producing water-absorbing polymer particles, comprising polymerization of a monomer solution or suspension, classification and drying of the resulting moist polymer gel, and comminution of the coarse fraction removed in the classification of the moist polymer gel, wherein the classification of the moist polymer gel is performed by means of a plurality of bar decks arranged in a cascade in a vibrating frame.

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Neustadt, Germany

Roland Krauss