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.

Abstract: In a process for continuous mixing of water-absorbing polymeric particles with liquids or other particles while the polymeric particles move in the product stream direction under their own weight, at least a portion of the material undergoing mixing acquires, through the rotational movement of at least one mixing tool secured to a rotating shaft, a momentum opposite the product stream direction.

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: 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: The invention relates to the production of superabsorbent polymers on a continuous belt reactor, comprising at least one rotating knife that cuts the formed polymer gel at the end of the continuous belt reactor, wherein the length of the cutting edge is at least 1 cm and the cutting edge is non-parallel to the rotation axis.

Abstract: A process for producing water-absorbing polymer particles by polymerizing droplets of a monomer solution in a surrounding gas phase, said monomer solution comprising at least one azo compound and at least one persulfate, the resulting polymer particles having a water content of at least 5% by weight, and being aftertreated thermally at a temperature of at least 100° C. for at least 5 minutes.

Abstract: The invention relates to a method for the transportation of a monomer composition in which a composition comprising an aqueous solution of partially or entirely neutralized acrylic acid or overneutralized acrylic acid is placed in a transport means or sent through a pipe. The method according to the invention is characterized in that it has an increased level of safety during the transportation of acrylic acid monomers, an improved quality of the resulting product, and a high degree of efficiency. The method ensures safe transport of the highly reactive acrylic acid. The amount of polymerization inhibitors added to said acrylic acid may be reduced. An additional advantage is the minimization of the formation of dimeric acrylic acid. Tempering of containers, pipes, and pipelines may be omitted.

Abstract: The invention relates to a process for production of superabsorbent polymers on a continuous belt reactor, wherein a continuous polymerization belt rests at least partly upon the upper surface of at least one continuous support belt and the at least one continuous support belt slides at least partly on a fixed surface.

Abstract: The invention relates to the production of superabsorbent polymers comprising conveying a polymer gel having acid groups on an oscillating conveyor belt to a continuous through-circulation belt dryer, wherein the belt speed of the conveyor belt is at least 0.4 m/s.

Abstract: A process for producing water-absorbing polymer particles by polymerizing droplets of a monomer solution in a surrounding gas phase, the resulting polymer particles having a water content of at least 5% by weight, and being aftertreated thermally in the fluidized state in the presence of steam at a temperature of at least 60° C.

Abstract: In a process for producing water-absorbing polymeric particles which comprises generating droplets comprising monomers, polymerizing the monomers in a heated gas phase surrounding the droplets and flowing the gas through the polymerization reactor, the temperature of the gas leaving the polymerization reactor is closed-loop controlled.

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: A process for producing polymer particles by polymerizing liquid droplets in a gas phase surrounding the droplets, said droplets comprising at least one monomer and being coated with particulate solids during the polymerization.