Abstract: Provided herein are fluid-absorbent articles, fluid absorbent cores, and fluid-absorbent mixtures with improved properties, especially rewet performance and liquid acquisition. The fluid-absorbent article includes (A) an upper liquid-pervious sheet, (B) a lower liquid-impervious sheet, (C) a fluid-absorbent core including from 60 to 20% by weight fibrous material and from 40 to 80% by weight of at least a first type of water-absorbent polymer particles, (G) and at least a second type of water-absorbent polymer particles (H) based on the sum of water-absorbent polymer particles and fibrous material, (D) an optional acquisition-distribution layer (D) between (A) and (C), (F) other optional components, wherein the first type of water absorbent polymer particles (G) of the fluid-absorbent core (C) have a SFC of at least 20×10?7 cm3·s/g, and wherein the at least second type of water-absorbent polymer particles (H) of the fluid-absorbent core have a sphericity of at least 0.80.

Abstract: In a method of measuring parameters of superabsorbents, the absorption capacity of superabsorbents is determined under pressure, by reducing the pressure applied to a sample of the superabsorbent stepwise and determining the absorption capacity at each pressure. In addition, the rise in absorption capacity after a reduction in pressure is measured as a function of time and this is used to calculate the swelling constant k or the characteristic swelling time ?. Swelling constant or characteristic swelling time or the magnitude of the difference in absorption capacity at two different pressures are used to determine further parameters of the superabsorbent.

Abstract: Superabsorbent mixtures M comprising at least 70% by weight of superabsorbent A having a liquid absorption of 20 g/g (T20) of less than 300 s and/or a volumetric liquid absorption under pressure 0.3 psi (2.07 kPa) (VAUL) with a ? value of less than 400 s, and at least 5% by weight of superabsorbent B having a centrifuge retention capacity (CRC) of at least 30 g/g.

Abstract: In a method of measuring parameters of superabsorbents, the absorption capacity of superabsorbents is determined under pressure, by reducing the pressure applied to a sample of the superabsorbent stepwise and determining the absorption capacity at each pressure. In addition, the rise in absorption capacity after a reduction in pressure is measured as a function of time and this is used to calculate the swelling constant k or the characteristic swelling time ?. Swelling constant or characteristic swelling time or the magnitude of the difference in absorption capacity at two different pressures are used to determine further parameters of the superabsorbent.

Abstract: A highly permeable superabsorbent is prepared by a process comprising polymerizing an aqueous monomer solution comprising a) at least one ethylenically unsaturated monomer which bears acid groups and is optionally at least partly in salt form, b) at least one crosslinker, c) at least one initiator, d) optionally one or more ethylenically unsaturated monomers copolymerizable with the monomers mentioned under a), and e) optionally one or more water-soluble polymers; drying the resulting polymer, optionally grinding the dried polymer and sieving the ground polymer, optionally surface postcrosslinking the dried and optionally ground and sieved polymer, adding x-ray-amorphous aluminum hydroxide powder after drying, grinding or sieving, and, if surface postcrosslinking is conducted, during or after this surface postcrosslinking, adding 0.

Abstract: An apparatus for production of pulverulent polymers having a reactor for droplet polymerization with an apparatus for dropletization of a monomer solution for the preparation of the polymer. The apparatus for dropletization has holes through which the monomer solution is introduced, an addition point for a gas above the apparatus for dropletization, at least one gas withdrawal point at the periphery of the reactor and a fluidized bed, wherein at least one of the following is fulfilled: an apparatus for increasing turbulence in the gas flow is disposed in the region of the apparatus for dropletization of the monomer solution, an apparatus for increasing turbulence in the gas flow is disposed in the region of the addition point for the gas, the addition point for gas is configured such that elevated turbulence is generated. A process for producing pulverulent polymers, in which an increase in flow turbulence in the gas flow in the region of the apparatus for dropletization also is disclosed.

Abstract: Superabsorbent mixtures M comprising at least 70% by weight of superabsorbent A having a liquid absorption of 20 g/g (T20) of less than 300 s and/or a volumetric liquid absorption under pressure 0.3 psi (2.07 kPa) (VAUL) with a ? value of less than 400 s, and at least 5% by weight of superabsorbent B having a centrifuge retention capacity (CRC) of at least 30 g/g.

Abstract: The invention relates to a process for producing long-term color stable superabsorbent polymer particles, comprising polymerization of a monomer solution, drying the resulting polymer gel, optionally grinding and classifying the resulting dried polymer gel and thermally surface post-crosslinking and cooling the resulting polymer particles, wherein a thermal surface post-cross-linker and hydrogen peroxide are added to the polymer particles prior to the thermal surface post-crosslinking.

Abstract: The present invention relates to a process for producing surface-postcrosslinked water-absorbent polymer particles by coating of water-absorbent polymer particles having a content of residual monomers in the range from 0.03 to 15% by weight with at least one surface-postcrosslinker and thermal surface-postcrosslinking at temperatures in the range from 100 to 180° C.

Abstract: A method of measuring indices in superabsorbents, by initially charging excess aqueous solution or dispersion, swelling the superabsorbent in the initially charged aqueous solution or dispersion while stirring, dissolving or dispersing a component A in the aqueous solution or dispersion, measuring the enrichment of component A in the aqueous solution or dispersion during the swelling of the superabsorbent, using the enrichment of component A in the aqueous solution or dispersion to measure the time-dependent swelling characteristics and using these to determine the swelling constant k or the characteristic swell time T, the index being dependent on the permeability of the superabsorbent, and ascertaining the index by means of a correlation measured beforehand between swelling constant k and index or characteristic swell time T and index.

Abstract: A highly permeable superabsorbent is prepared by a process comprising polymerizing an aqueous monomer solution comprising a) at least one ethylenically unsaturated monomer which bears acid groups and is optionally at least partly in salt form, b) at least one crosslinker, c) at least one initiator, d) optionally one or more ethylenically unsaturated monomers copolymerizable with the monomers mentioned under a), and e) optionally one or more water-soluble polymers; drying the resulting polymer, optionally grinding the dried polymer and sieving the ground polymer, optionally surface postcrosslinking the dried and optionally ground and sieved polymer, wherein, after drying, grinding or sieving, and, if surface postcrosslinking is conducted, during or after this surface postcrosslinking, x-ray-amorphous aluminum hydroxide powder is added.

Abstract: An apparatus for production of pulverulent polymers having a reactor for droplet polymerization with an apparatus for dropletization of a monomer solution for the preparation of the polymer. The apparatus for dropletization has holes through which the monomer solution is introduced, an addition point for a gas above the apparatus for dropletization, at least one gas withdrawal point at the periphery of the reactor and a fluidized bed, wherein at least one of the following is fulfilled: an apparatus for increasing turbulence in the gas flow is disposed in the region of the apparatus for dropletization of the monomer solution, an apparatus for increasing turbulence in the gas flow is disposed in the region of the addition point for the gas, the addition point for gas is configured such that elevated turbulence is generated. A process for producing pulverulent polymers, in which an increase in flow turbulence in the gas flow in the region of the apparatus for dropletization also is disclosed.

Abstract: Provided herein are fluid-absorbent articles, fluid absorbent cores, and fluid-absorbent mixtures with improved properties, especially rewet performance and liquid acquisition. The fluid-absorbent article includes (A) an upper liquid-pervious sheet, (B) a lower liquid-impervious sheet, (C) a fluid-absorbent core including from 60 to 20% by weight fibrous material and from 40 to 80% by weight of at least a first type of water-absorbent polymer particles, (G) and at least a second type of water-absorbent polymer particles (H) based on the sum of water-absorbent polymer particles and fibrous material, (D) an optional acquisition-distribution layer (D) between (A) and (C), (F) other optional components, wherein the first type of water absorbent polymer particles (G) of the fluid-absorbent core (C) have a SFC of at least 20×10?7 cm3·s/g, and wherein the at least second type of water-absorbent polymer particles (H) of the fluid-absorbent core have a sphericity of at least 0.80.

Abstract: A fluid-absorbent article includes an upper liquid-pervious layer (A), a lower liquid-impervious layer (B), a fluid-absorbent core (C) between (A) and (B) including at least 60% by weight of non-surface postcrosslinked fluid-absorbent polymer particles and not more than 40% by weight of fibrous material, based on the sum of non-surface postcrosslinked fluid-absorbent polymer particles and fibrous material. An acquisition-distribution layer (D) between (A) and (C) includes at least 90% by weight of synthetic fibers and not more than 10% by weight of cellulose based fibers, based on the sum of synthetic fibers and cellulose based fibers. The basis weight of the acquisition-distribution layer (D) is at least 70 gsm. The fluid-absorbent polymer particles have a saline flow conductivity (SFC) of less than 5×10?7 cm3s/g and an AUHL of less than 15 g/g. Preferably the acquisition-distribution layer (D) is a non-woven web including a three dimensional network of fibers.

Abstract: A device for protecting against the scouring of granular fillings submerged in gravity structures in which a filling with granular materials must be deposited once the structures are submerged, so that the structures reach a weight sufficient to en sure the stability thereof against the actions to which they are subjected. The device consists of one or more porous covers that sit and/or are secured as an upper closure of the structure to protect the inner filling, each of the covers having a plurality of openings that are distributed on the surface thereof and have a size suitable to allow the passage of the filling material, which filling material is transferred to the inside of the structure simply by pouring until a height close to the cover is reached, leaving a margin or chamber between the two that is suitable for generating an internal turbulence that dissipates wave energy and incident currents, thereby making it difficult for the filling material to escape from the inside through the openings.

Abstract: The present invention relates to a process for producing surface-postcrosslinked water-absorbent polymer particles by coating of water-absorbent polymer particles having a content of residual monomers in the range from 0.03 to 15% by weight with at least one surface-postcrosslinker and thermal surface-postcrosslinking at temperatures in the range from 100 to 180° C.

Abstract: A device for protecting against the scouring of granular fillings submerged in gravity structures in which a filling with granular materials must be deposited once the structures are submerged, so that the structures reach a weight sufficient to en sure the stability thereof against the actions to which they are subjected. The device consists of one or more porous covers that sit and/or are secured as an upper closure of the structure to protect the inner filling, each of the covers having a plurality of openings that are distributed on the surface thereof and have a size suitable to allow the passage of the filling material, which filling material is transferred to the inside of the structure simply by pouring until a height close to the cover is reached, leaving a margin or chamber between the two that is suitable for generating an internal turbulence that dissipates wave energy and incident currents, thereby making it difficult for the filling material to escape from the inside through the openings.

Abstract: The present invention relates to a process for producing surface-postcrosslinked water-absorbent polymer particles by coating of water-absorbent polymer particles having a content of residual monomers in the range from 0.03 to 15% by weight with at least one surface-postcrosslinker and thermal surface-postcrosslinking at temperatures in the range from 100 to 180° C.

Abstract: The present invention relates to a process for producing surface-postcrosslinked water-absorbent polymer particles comprising polymerizing droplets of a monomer solution, wherein water-absorbent polymer particles having an average particle diameter from 420 to 700 ?m, an amount of water-absorbent polymer particles having a particle size of less than 300 ?m of less than 5% by weight and an amount of water-absorbent polymer particles having a particle size of more than 800 ?m of less than 5% by weight are coated with at least one surface-postcrosslinker and thermal surface-postcrosslinked.

Abstract: The present invention relates to a process for producing surface-postcrosslinked water-absorbent polymer particles comprising polymerizing droplets of a monomer solution, wherein water-absorbent polymer particles having an average particle diameter from 150 to 400 ???, an amount of water-absorbent polymer particles having a particle size of less than 100 ??? of less than 5% by weight and an amount of water-absorbent polymer particles having a particle size of more than 500 ??? of less than 5% by weight are coated with at least one surface-postcrosslinker and thermal surface-postcrosslinked.