Abstract: A process for producing water-absorbing polymer particles by polymerizing droplets of a monomer solution in a gas phase surrounding the droplets and postcrosslinking the polymer particles, wherein the postcrosslinked polymer particles are at least partly coated.

Abstract: The present invention relates to fluid-absorbent articles, comprising an upper liquid-pervious layer, a lower liquid-impervious layer, a fluid-absorbent core, wherein the fluid-absorbent core comprises a fibrous material and 10 to 95% by weight of spherical fluid-absorbent polymer particles, and an acquisition distribution layer, wherein the acquisition distribution layer comprises a fibrous material and 0 to 20% by weight of spherical fluid-absorbent polymer particles.

Abstract: 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.

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: A process for producing water-absorbing polymer particles by polymerizing droplets of a monomer solution in a surrounding gas phase in a reaction chamber, wherein the monomer solution is metered into the reaction chamber via at least one bore, and the diameter is from 210 to 290 ?m per bore and the metering rate is from 0.9 to 5 kg/h per bore.

Abstract: A process for thermally surface postcrosslinking water-absorbing polymer particles in a fluidized bed generated by means of a carrier gas, wherein the surface postcrosslinker is supplied to the fluidized bed in gaseous form.

Abstract: A process for producing water-absorbing polymer particles by polymerizing droplets of a monomer solution in a surrounding gas phase, wherein the monomer solution comprises at least 0.0002% by weight of oxygen and the oxygen content of the gas phase is at least 0.5% by volume.

Abstract: 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.

Abstract: A process for producing water-absorbing polymer particles with improved blood absorbence by polymerizing droplets of a monomer solution in a surrounding gas phase, wherein the monomer solution comprises a surfactant.

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

Abstract: The present invention relates to an apparatus for producing water-absorbing polymer particles by polymerizing monomers on a continuous conveyor belt, wherein joins of the conveyor belt and/or damage on the conveyor belt surface have been sealed with a sealing composition.

Abstract: The present invention relates to a method for producing water-absorbent polymer particles by radiation-induced polymerization on a continuously revolving belt, electromagnetic radiation having a wavelength of greater than 400 nm being shielded.

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: What is described is a process for producing water-absorbing resins, in which a) acrylic acid is prepared at an acrylic acid production site, b) the acrylic acid prepared is dissolved in water at the acrylic acid production site to obtain an aqueous acrylic acid solution, c) the aqueous acrylic acid solution is fed into a pipeline at the acrylic acid production site and passed through the pipeline to an acrylic acid processing site and d) the aqueous acrylic acid solution is subjected to a free-radical polymerization at the acrylic acid processing site. The process ensures safe transport of the highly reactive acrylic acid. Endangerment as a result of premature polymerization, as in the case of glacial acrylic acid, is ruled out, since the acrylic acid is “diluted” by the aqueous solvent and the specific heat capacity and the evaporation enthalpy of the water limit the maximum temperature rise.

Abstract: Aqueous dispersions of crosslinked emulsion polymers comprising tertiary ester groups, comprising (a) at least 50% by weight of an ester derived from a tertiary alcohol and an ethylenically unsaturated C3 to C5 carboxylic acid, (b) 0.001% to 5.0% by weight of at least one compound having at least two ethylenically unsaturated double bonds, and (c) 0% to 49.999% by weight of at least one other monoethylenically unsaturated compound in interpolymerized form and having an average particle size of not more than 1000 nm, and water-absorbing materials obtainable by coating a backing material with the aqueous dispersion described of crosslinked emulsion polymers comprising tertiary ester groups, drying and heating the thus treated backing material to a temperature of at least 140° C. to form carboxyl groups from the tertiary ester groups of the emulsion polymer and at least partly neutralizing the carboxyl groups, and also the use of the water-absorbing materials as an absorbent for water and aqueous fluids.