Provided is a method for producing a water-absorbing resin powder excellent in water absorption speed. The method for producing a water-absorbing resin powder includes a polymerization step of polymerizing an aqueous monomer solution to obtain a crosslinked hydrogel polymer and a gel-crushing step of crushing the crosslinked hydrogel polymer after the polymerization step using a gel-crushing device to obtain a crosslinked particulate hydrogel polymer, in which the gel-crushing device includes an input port, a discharge port, and a main body incorporating a plurality of rotation axes each including a crusher, and in the gel-crushing step, the crosslinked hydrogel polymer is continuously put into the input port and the crosslinked particulate hydrogel polymer is continuously taken out from the discharge port, the crosslinked hydrogel polymer to be put into the input port has a rate of polymerization of 90 mass % or more, a gel-crushing coefficient is 0.020 J/g.Math.sec or more and 3.0 J/g.Math.sec or less, and the crosslinked particulate hydrogel polymer discharged from the discharge port has a mass average particle diameter of 500 m or less as converted to a solid content.

The present invention relates to a process for preparation of superabsorbent polymer with high fluid absorptivity. The present invention also relates to a composition comprising said superabsorbent polymer particles and their use for absorbing aqueous fluids, for example in the agricultural industry.

An apparatus and method of high pressure treatment of bulk material by extraction and/or impregnation may involve treating bulk material in an internal volume of a pressure vessel apparatus at a high pressure level in a range from 40 to 1000 bar under isolation from the environment. The high pressure treatment may be performed charge-wise in a closed system in the pressure vessel apparatus in that the bulk material is supplied charge-wise to the internal volume with the pressure vessel apparatus closed and is positioned in at least one treatment plane. Upon completion of the high pressure treatment, the bulk material is discharged charge-wise from the internal volume with the pressure vessel apparatus closed. This also gives advantages in terms of handling, especially also with regard to material flow, and with regard to operational reliability.

An apparatus and method for high pressure treatment of bulk material by extraction and/or impregnation may involve high pressure treating bulk material in a high pressure treatment volume of a pressure vessel apparatus at a high pressure level, especially high pressure in the range from 40 to 1000 bar. The method comprises at least the three following step sequences that are each controllable individually: pressurization, high pressure treatment, and depressurization. The high pressure treatment is performed in a continuous manner in the high pressure treatment volume. The high pressure treatment volume or the entire pressure vessel apparatus is in a fixed arrangement during the high pressure treatment. The continuity of the high pressure treatment is ensured solely by means of the high pressure treatment volume. This especially enables engineering optimization of high pressure treatment processes, for example extraction.

A method of recycling superabsorbent polymers derived from a used absorbent article, the method including: treating the superabsorbent polymers with ozone water after inactivation; reactivating, with an alkaline aqueous solution, the superabsorbent polymers treated with the ozone water; and adding hydrophilic fine particles to the superabsorbent polymers reactivated with the alkaline aqueous solution and then drying the superabsorbent polymers.

The disclosure provides a very simple and convenient method for producing a porous material of a water-soluble polymer. The herein disclosed method for producing a porous material of a water-soluble polymer includes a step of preparing a solution in which a water-soluble polymer is dissolved in a mixed solvent of water mixed with a solvent having a boiling point higher than that of water, and a step of evaporating and thereby removing the mixed solvent from the solution. The solubility of the water-soluble polymer in the solvent having a boiling point higher than that of water is lower than the solubility of the water-soluble polymer in water. Voids are formed, in the step of evaporating and thereby removing the mixed solvent, by the solvent having a boiling point higher than that of water.

A water-soluble film, comprising a first water-soluble film, wherein the first water soluble film disintegrates in water within less than about 24 hours and dissolves in water within less than about 48 hours as measured by the MSTM-205 at 20° C. The disclosure provides a water-soluble film comprising a first water-soluble film that disintegrates in water within less than 24 hours and dissolves in water within less than 48 hours as measured by MSTM-205 at 20° C. The first water-soluble film optionally may be further characterized in that it does not disintegrate in water for at least about 1 hour and does not dissolve in water for at least about 1 hour as measured by MSTM-205 at 20° C. The disclosure further provides a water-soluble film comprising a first water-soluble film characterized in that the degradation and/or dissolution of the first water-soluble film is adapted to be activated by consumer handling.

Poly(acrylic acid)-based superabsorbent polymer (SAP) in a feed stream is converted with UV irradiation into poly(acrylic acid) (PAA) in a flow system. The UV total energy used to convert SAP into PAA is less than about 50 MJ/kg SAP.

A water-soluble film is provided that is capable of achieving deformation resistance during pouch storage as well as excellent water solubility of the film and excellent reduction in undissolved residues. A water-soluble film includes a polyvinyl alcohol-based resin, wherein a crystal long period Ds obtained from an X-ray profile obtained by small-angle X-ray scattering measurement in a water/methanol mixed solvent (volume ratio: 2/8) is from 10.0 to 30.0 nm and a rate of increase (DS−Da)/Da of the crystal long period Ds to a crystal long period Da obtained by small-angle X-ray scattering measurement before immersion in the solvent is 30% or more and 130% or less.

A water-soluble film, comprising a first water-soluble film, wherein the first water soluble film disintegrates in water within less than about 24 hours and dissolves in water within less than about 48 hours as measured by the MSTM-205 at 20° C. The disclosure provides a water-soluble film comprising a first water-soluble film that disintegrates in water within less than 24 hours and dissolves in water within less than 48 hours as measured by MSTM-205 at 20° C. The first water-soluble film optionally may be further characterized in that it does not disintegrate in water for at least about 1 hour and does not dissolve in water for at least about 1 hour as measured by MSTM-205 at 20° C. The disclosure further provides a water-soluble film comprising a first water-soluble film characterized in that the degradation and/or dissolution of the first water-soluble film is adapted to be activated by consumer handling.