Abstract: A process for removing metallic impurities from a product mass flow comprising water-absorbing polymer particles, wherein the product mass flow has a temperature of 35 to 90° C.

Abstract: A process for producing water-absorbing polymer particles, wherein the water-absorbing polymer particles are surface postcrosslinked with unsaturated fatty acids or derivatives thereof.

Abstract: 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.

Abstract: 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 m3/h per m3 of reactor volume.

Abstract: A process for producing water-absorbing polymer particles, wherein heated water-absorbing polymer particles are remoisturized and cooled in a high-speed mixer.

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, comprising polymerization of a monomer solution or suspension, drying the resulting polymer gel, and grinding and classifying the dried polymer gel, wherein the grinding is performed by means of a multistage roll mill, the first milling gap has a width of 500 to 5000 ?m, the product mass flow passing through the first milling gap is conducted through a magnetic separator to the second milling gap, and the second milling gap has a smaller gap width than the first milling gap.

Abstract: A process for producing water-absorbing polymer particles by polymerizing droplets of a monomer solution in a gas phase surrounding the droplets, wherein the particle surface is coated at least partly with at least one polymer and/or wax.

Abstract: A process for producing water-absorbing polymer particles, comprising polymerization, drying, comminution, classification and recycling of the undersize obtained in the classification, wherein the recycled undersize is coated with a reducing agent and/or inorganic particles.

Abstract: 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.

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: The invention relates to the production of superabsorbent polymers comprising polymerizing a monomer solution on a continuous belt reactor, wherein the consistency of the formed polymer gel at the end of the continuous belt reactor is controlled by adjusting the intensity of energy-rich radiation.

Abstract: A process for producing water-absorbing polymer particles, wherein an aqueous polymer gel is dried in a forced-air belt drier on a circulating conveyor belt and the surface of the conveyor belt has a roughness of at least 0.9 ?m.

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 polymer gel is removed from a polymerization reactor, stored intermediately as a particulate polymer gel in a delay vessel, removed by means of a first conveying device at the lower end of the delay vessel and dried, the intermediately stored particulate polymer gel being conveyed within the delay vessel by means of at least one second conveying device above the first conveying device in the direction of the first conveying device.

Abstract: A process for continuously producing water-absorbing polymer particles by polymerizing a monomer solution comprising acrylic acid and/or salts thereof, wherein the acrylic acid supplied has a dimeric acrylic acid content of at least 0.02% by weight and the dimeric acrylic acid content is kept essentially constant.

Abstract: A process for continuously producing water-absorbing polymer particles, wherein the acrylic acid used to produce the polymer particles has a low purity.

Abstract: 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.

Abstract: A process for producing water-absorbing polymer particles, comprising polymerization of a monomer solution or suspension, drying the resulting polymer gel, and grinding and classifying the dried polymer gel, wherein the grinding is performed by means of a multistage roll mill, the first milling gap has a width of 500 to 5000 ?m, the product mass flow passing through the first milling gap is conducted through a magnetic separator to the second milling gap, and the second milling gap has a smaller gap width than the first milling gap.

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.