Abstract: A process for producing water-absorbing polymer particles by polymerizing an aqueous monomer solution in a polymerization reactor with at least two axially parallel rotating shafts, wherein the polymerization is performed in the presence of an inert gas and under positive pressure.

Abstract: An apparatus for producing a water-absorbing polymer by polymerizing a monomer solution and drying the resulting hydrogel by means of a heated gas stream through effecting the drying in two or more temperature zones. A gas stream is flowed against the hydrogel upwardly in the upstream sector of the belt dryer and downwardly in the downstream sector of the belt dryer, the direction of flow being reversed at a water content of 15% to 45% by weight for the hydrogel. The hydrogel layer is flowed against in a belt dryer upwardly to some extent at least, the gas velocity being 5% to 30% of the gas velocity required to lift the hydrogel off the belt, to produce hygiene articles.

Abstract: The invention relates to a process for producing water-absorbing polymer particles, comprising thermal postcrosslinking in a contact dryer having external heated outer surfaces.

Abstract: A process for classifying water-absorbing polymer beads, wherein the polymer beads are separated into n particle size fractions by means of at least n screens and n is an integer greater than 1.

Abstract: A process for producing water-absorbing polymer particles, wherein an aqueous polymer gel is applied by means of a swivel belt to the conveyor belt of a forced-air belt drier, and the swivel belt, proceeding from one end position, is accelerated through a first pivot angle to an angular speed v1, decelerated through a second pivot angle to an angular speed v2 and decelerated through a third pivot angle to the other end position.

Abstract: The invention relates to the use of an apparatus for adding at least one solid or viscous liquid additive, or an additive dispersed in solvent, to a reactor interior of a reactor for preparing crosslinked, finely divided polymers by copolymerizing (a) water-soluble, monoethylenically unsaturated monomers and (b) from 0.001 to 5 mol %, based on the monomers (a), of monomers comprising at least two polymerizable groups, (c) from 0 to 20 mol %, based on the monomers (a), of water-insoluble monoethylenically unsaturated monomers, where the apparatus comprises at least one screw for conveying the at least one additive and the at least one screw ends in an addition orifice substantially flush with the inner wall of the reactor interior.

Abstract: The invention relates to a process for producing water-absorbing polymer particles, comprising handling water-absorbing polymer particles in intermediate silos, storage silos and/or big bag filing stations that are connected with vent lines having a mitered joint.

Abstract: A process for producing water-absorbing polymer particles, comprising the addition of a solid additive to a polymer gel by means of a conveying screw (1), wherein the solid additive and a gas volume flow are fed to the conveying screw (1) by means of an addition channel (2).

Abstract: The invention relates to a process for producing water-absorbing polymer particles, comprising thermal postcrosslinking in a contact dryer having external heated outer surfaces.

Abstract: A process for producing a water-absorbing polymer by polymerizing a monomer solution and drying the resulting hydrogel by means of a heated gas stream comprises effecting the drying in two or more temperature zones, and/or the gas stream is flowed against the hydrogel upwardly in the upstream sector of the belt dryer and downwardly in the downstream sector of the belt dryer, the direction of flow being reversed at a water content of 15% to 45% by weight for the hydrogel, and/or the hydrogel layer is flowed against in a belt dryer upwardly to some extent at least, the gas velocity being 5% to 30% of the gas velocity required to lift the hydrogel off the belt, also apparatus for carrying out the process and use of the water-absorbing polymers produced by the process to produce hygiene articles.

Abstract: A process for producing water-absorbing polymer particles, comprising the addition of a solid additive to a polymer gel by means of a conveying screw (1), wherein the solid additive and a gas volume flow are fed to the conveying screw (1) by means of an addition channel (2).

Abstract: A process for producing water-absorbing polymer particles by polymerizing an aqueous monomer solution in a polymerization reactor with at least two axially parallel rotating shafts, wherein the polymerization is performed in the presence of an inert gas and under positive pressure.

Abstract: A process for producing a water-absorbing polymer by polymerizing a monomer solution and drying the resulting hydrogel by means of a heated gas stream comprises effecting the drying in two or more temperature zones, and/or the gas stream is flowed against the hydrogel upwardly in the upstream sector of the belt dryer and downwardly in the downstream sector of the belt dryer, the direction of flow being reversed at a water content of 15% to 45% by weight for the hydrogel, and/or the hydrogel layer is flowed against in a belt dryer upwardly to some extent at least, the gas velocity being 5% to 30% of the gas velocity required to lift the hydrogel off the belt, also apparatus for carrying out the process and use of the water-absorbing polymers produced by the process to produce hygiene articles.

Abstract: 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° C., and also to an apparatus for carrying out the process.

Abstract: 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.

Abstract: A process for producing water-absorbing polymer particles, wherein a product stream comprising water-absorbing polymer particles is tested for nonferritic metallic impurities by means of an eddy current detector.

Abstract: The invention relates to the use of an apparatus for adding at least one solid or viscous liquid additive, or an additive dispersed in solvent, to a reactor interior of a reactor for preparing crosslinked, finely divided polymers by copolymerizing (a) water-soluble, monoethylenically unsaturated monomers and (b) from 0.001 to 5 mol %, based on the monomers (a), of monomers comprising at least two polymerizable groups, (c) from 0 to 20 mol %, based on the monomers (a), of water-insoluble monoethylenically unsaturated monomers, where the apparatus comprises at least one screw for conveying the at least one additive and the at least one screw ends in an addition orifice substantially flush with the inner wall of the reactor interior.

Abstract: The invention relates to the use of an apparatus for adding at least one solid or viscous liquid additive, or an additive dispersed in solvent, to a reactor interior of a reactor for preparing crosslinked, finely divided polymers by copolymerizing (a) water-soluble, monoethylenically unsaturated monomers and (b) from 0.001 to 5 mol %, based on the monomers (a), of monomers comprising at least two polymerizable groups, (c) from 0 to 20 mol %, based on the monomers (a), of water-insoluble monoethylenically unsaturated monomers, where the apparatus comprises at least one screw for conveying the at least one additive and the at least one screw ends in an addition orifice substantially flush with the inner wall of the reactor interior.

Abstract: The invention relates to a mixing kneader comprising at least two shafts (2,3) configured as hollow shafts, on whose surfaces kneading bars (4) are disposed on elements (5). The construction of the shafts is selected in such a way that the resonant frequencies of the shafts have a separation of at least 5% from the excitation frequencies. At least one of the shafts is preferably flowed through by a temperature-control medium, the inlet being disposed on one side and the outlet on the other side of the shaft. The mixing kneader preferably comprises at least one orifice above the shafts which is configured as a dome, the dome being closed by a displacer (22). In addition, at least one orifice for product withdrawal is provided, whose orifice cross section is adjustable during operation.

Abstract: The invention relates to a mixing kneader comprising at least two shafts (2,3) configured as hollow shafts, on whose surfaces kneading bars (4) are disposed on elements (5). The construction of the shafts is selected in such a way that the resonant frequencies of the shafts have a separation of at least 5% from the excitation frequencies. At least one of the shafts is preferably flowed through by a temperature-control medium, the inlet being disposed on one side and the outlet on the other side of the shaft. The mixing kneader preferably comprises at least one orifice above the shafts which is configured as a dome, the dome being closed by a displacer (22). In addition, at least one orifice for product withdrawal is provided, whose orifice cross section is adjustable during operation.