Basf Se Corporation

Karl J Possemiers

Matthias Weismantel

Ronny De Kaey

Rüdiger Funk

Dominicus Van Esbroeck

Michael De Marco

Uwe Stueven

Filip Mees

Leo Van Miert

Thomas Daniel

Andreas Daiss

Oskar Stephan

Monte Alan Peterson

Annemarie Hillebrecht

Claus Hechler

Thomas Pfeiffer

Wilfried Heide

Ruediger Funk

Ann Becker

Patrick Neal Hamilton

Marc Gerardus Nicolas Grimmon

Louis Claessens

Steven Lippens

Michael Marco

The invention relates to a classification process for superabsorbent polymer particles, comprising classifying the water-absorbent polymer particles in a screen machine under reduced pressure wherein the pressure above the uppermost sieve is from 0 to 4.0 mbar per sieve higher than below the undermost sieve.

Classification process for superabsorbent polymer particles

The invention relates to a process for operating a mixing kneader, comprising one or more shafts on whose surfaces are disposed kneading bars and which are surrounded by a casing, comprising the following steps:

Process for operating a mixing kneader

A process for continuously producing water-absorbing polymer particles, wherein the monomer stems from at least two different sources and the monomer from one source differs from the monomer from at least one other source in the content of at least one secondary component.

Method for the production of water-absorbing polymer particles

The invention relates to a neutralization process in which at least one ethylenically unsaturated carboxylic acid is preneutralized at least partly with a base, wherein the preneutralized solution is divided into at least two part-solutions and at least one part-solution is aftertreated so as to form part-solutions with different degree of neutralization and/or solids content, and also to an apparatus for carrying out the process.

Neutralization process

The invention relates to a continuous neutralization process in which at least one ethylenically unsaturated carboxylic acid is neutralized at least partly with a base and the temperature of the neutralized solution is less than 70&#xb0; C., and also to an apparatus for carrying out the process.

A process for continuously producing water-absorbing polymer particles, in a continuous polymerization reactor, wherein the amount of initiator used and/or the intensity of the UV radiation optionally used to initiate the polymerization is reduced after the startup of the polymerization reactor.

Process for continuously producing water-absorbing polymer particles

A process for producing water-absorbing polymer particles with a low centrifuge retention capacity by polymerizing in a continuous kneading reactor under an inert gas volume flow of at most 10 m/h per mof reactor volume.

Method for manufacturing water-absorbing polymer particles with a low centrifuge retention capacity

The invention relates to a neutralization process in which at least one ethylenically unsaturated carboxylic acid is neutralized at least partly with a base and at least one stream of the neutralization is determined continuously, and also to an apparatus for carrying out the process.

A process for continuous thermal postcrosslinking of water-absorbing polymer particles, wherein the postcrosslinker is applied to the water-absorbing polymer particles by means of suitable nozzles and the nozzles are exchanged or cleaned via the interior of a glovebox adjoining the plant section comprising the nozzle.

Method for the continuous thermal secondary surface cross-linking of water-absorbing polymer particles

The invention relates to a process for producing a water-absorbing resin by polymerization of a reaction mixture comprising at least one hydrophilic monomer and, if appropriate, at least one crosslinker in a reactor, which comprises admixing the reaction mixture with at least one first portion of a particulate additive before the reaction mixture has reached a residence time of 40% of the overall residence time in the reactor and with at least one second portion of a particulate additive when the reaction mixture has reached a residence time of 45% or more of the overall residence time in the reactor, the additive being selected from water-absorbing resin powders, fillers and mixtures thereof, the total solids content of monomer and additive being in the range from 30% to 60% by weight, the amount of additive being in the range from 5% to 50% by weight, based on the monomers, and the weight ratio of the first portion to the second portion of the additive being in the range from 10:1 to 1:5. The resin powder is recycled fine-sized material for example. Not only the residual monomer content, specifically the residual crosslinker content, but also the level of extractables in the water-absorbing resin are reduced by the method of addition described. A high fraction of additives can be incorporated without the properties of the water-absorbing resin obtained being adversely affected. The additives enter a sufficiently firm bond with the resin, so that no excessive dusting occurs on exposure to mechanical stress.

Production of a water-absorbing resin to which a particulate additive is admixed

A process for classifying water-absorbing polymer beads, wherein screens having different mesh sizes are used before and after the postcrosslinking to remove the oversize.

Method for grading water-absorbent polymer particles

The invention relates to a process for continuously preparing water-absorbing polymer particles by mixing a monomer solution with a redox initiator consisting of at least one oxidizing agent and at least one reducing agent and polymerizing it, wherein the monomer solution is mixed with at least one oxidizing agent upstream of the polymerization reactor and the at least one reducing agent is metered into the polymerization reactor, and also to an apparatus for performing the process.

Polymerization process

The present invention relates to a process for continuously preparing water-absorbing polymers by mixing a monomer solution with at least one crosslinker and polymerizing the resulting mixture, wherein the residence time of the mixture between the addition of the at least one crosslinker and the entry into the polymerization reactor is less than 180 seconds, and also to an apparatus for performing the process.

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Gravenwezel, Belgium

Karl J Possemiers