Abstract: A process for continuously preparing water-absorbing polymer beads, comprising the drying of a polymer gel on a forced-air belt dryer, the water content of the polymer gel being used to control the forced-air belt dryer during or after the drying.

Abstract: A process for continuously preparing water-absorbing polymer beads by determining at least one particulate delivery material mass flow by means of incident electromagnetic waves.

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 continuously classifying water-absorbing polymer beads by means of at least one screen, at least one screen having at least one guide device on the screen surface.

Abstract: A process for preparing postcrosslinked water-absorbing polymer beads with high absorption by polymerizing droplets of a monomer solution in a gas phase surrounding the droplets, wherein the solids content of the monomer solution is at least 35% by weight and the polymer beads have a mean diameter of at least 150 ?m.

Abstract: A process for preparing water-absorbing polymer beads with high permeability by polymerizing droplets of a monomer solution, comprising monomers bearing acid groups, in a gas phase surrounding the droplets, wherein the monomer solution comprises polyvalent cations and the polymer beads have a mean diameter of at least 150 ?m.

Abstract: 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.

Abstract: A process for preparing water-absorbing polymer beads with high permeability by polymerizing droplets of a monomer solution in a gas phase surrounding the droplets, wherein a water-insoluble inorganic salt is suspended in the monomer solution and the polymer beads have a mean diameter of at least 150 ?m.

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 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: The invention relates to a process for preparing water-absorbing polymers by polymerizing a monomer solution, wherein the oxygen content of the monomer solution has been reduced by addition of at least one reducing agent before the polymerization.

Abstract: The invention relates to processes for preparing water absorbing polymers by polymerization of a monomer solution comprising allyl acrylate and/or allyl alcohol, the solution comprising not more than 0.002% by weight of allyl acrylate and/or allyl alcohol, based on acrylic acid, to aqueous monomer solutions for producing water absorbing polymers, to water absorbing polymers, to processes for producing hygiene articles and also to hygiene articles.

Abstract: Process for classifying a particulate water-absorbing resin using a sieving apparatus at a reduced pressure compared with the ambient pressure and a sieving apparatus for classifying a particulate water-absorbing resin at a reduced pressure compared with the ambient pressure.

Abstract: A process for producing water-absorbing polymeric particles by dropletization polymerization in the gas phase, which comprises drying the polymeric particles after the polymerization in a fluidized bed, the water-absorbing polymeric particles themselves, hygiene articles comprising these water-absorbing polymeric particles and also apparatus for implementing the process.

Abstract: Water-absorbing polymeric particles are produced by spray polymerization of a monomer solution in a process wherein the monomer solution is spray dispensed and at least one crosslinker accumulates in the region of the droplet surface, and are useful in hygiene articles.

Abstract: The invention relates to a cross-linked, water-swellable polymer that contains polymerized into it moieties of a) water-soluble, monoethylenically unsaturated monomers, and b) 0.001 to 5 mole % based on the monomers a) of a cross-linking combination, b1) a frist cross-linking agent with at least two (meth)acrylic ester moieties in the molecule and b2) a second cross-linking agent with at least two (meth)allyloxy moieties in the molecule, the molar ratio of b1) to b2) ranging from 0.7:1 to 10:1. The polymer according to the invention has a balanced property profile as regards absorptivity, gel strength, absorption speed and extractable componenents and can be advantageously produced by a continuous method.

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: Disclosed is a method for the continuous production of crosslinked, particulate, gel-type polymers by copolymerizing a) water-soluble, monoethylenically unsaturated monomers, b) 0.001 to 5 molar percent of monomers containing at least two polymerizable groups, the percentage being relative to the monomers (a), in a mixer. The substances that are added at the beginning of the kneader are conveyed in an axial direction towards the end of the mixer. The inventive method is characterized in that at least one of the following conditions is met: i) the filling level in the kneader mixer is at least 71 percent; ii) the water-soluble, monoethylenically unsaturated monomers contain up to 150 ppm of a semicyclic ether of a hydroquinone; iii) the temperature in the polymerization zone exceeds 65° C.; iv) the kneader has a remixing rate of less than 0.33.

Abstract: The present invention relates to a process for postcrosslinking water-absorbing polymeric particles in the absence of oxidizing gases, to the water-absorbing polymers preparable by the process and to their use in hygiene articles and packaging materials.

Abstract: Hydrogel particles are produced by a drying step followed sequentially by precomminuting, grinding, separating, and further drying of coarse particles.