Abstract: A water-absorbing resin that exhibits excellent absorption performance and a high permeation rate with respect to liquids to be absorbed, and that effectively reduces liquid leakages, even in an absorbent body using a large amount of the water-absorbing resin. The water-absorbing resin is formed from a polymer of a water-soluble ethylenically unsaturated monomer, and when a cross-sectional image of the water-absorbing resin obtained by X-ray computer tomography is observed, the percent area of cavity portions in the cross-sectional image is 2-10%. The liquid flow rate index when a physiological saline liquid column flow rate test is performed on the water-absorbent resin having a particle diameter of 250 to 500 ?m at 37° C. is 5-20.

Abstract: Provided is a water-absorbent resin that quickly absorbs water, even in sandbag in which a large amount of the water-absorbent resin has been used, that does not easily form unswollen lump, and that has a high gel swelling volume when water is used to swell the water-absorbent resin. This water-absorbent resin is configured from a polymer of water-soluble ethylenic unsaturated monomers. The physiological-saline absorption capacity of the water-absorbent resin is 40-60 g/g. When a cross-sectional image of the water-absorbent resin is observed by x-ray computed tomography, the fraction of the area of the cross-sectional image that is hollow portions (the hollow area ratio of the cross-sectional image), as calculated on the basis of formula (I), is no more than 10%.

Abstract: Provided is a non-destructive method for evaluating the structure of a water-absorbing resin which can be advantageously used for controlling various properties of the water-absorbing resin. This non-destructive method for evaluating the structure of a water-absorbing resin involves non-destructively evaluating the structure of a water-absorbing resin through an X-ray computer tomographic technique, wherein the method comprises a step 1 for installing the water-absorbing resin to be evaluated on a test piece stage of an X-ray computer tomography device, a step 2 for performing X-ray computer tomography on the water-absorbing resin using the X-ray computer tomography device and acquiring tomographic image data of the water-absorbing resin, and a step 3 for analyzing the tomographic image data using image analysis software and obtaining a tomographic image of the water-absorbing resin.

Abstract: A water-absorbent resin that exhibits a high liquid-retention capacity under a load and a small amount of re-wet, even when it is used in an absorbent material having a low proportion of hydrophilic fibers. The water-absorbent resin includes a polymer of a water-soluble ethylenically unsaturated monomer, wherein when a cross-sectional image of the water-absorbent resin is observed using X-ray computed tomography, the water-absorbent resin has cavity area percentage in the cross-sectional image of 10% or less.

Abstract: The purpose of the present invention is to provide a water-absorbent resin having excellent absorption properties in a localized absorption area. Provided is a water-absorbent resin composed of a polymer of water-soluble ethylenically unsaturated monomers, wherein the physiological saline absorption rate is 5-30 seconds, and the diffusion absorption rate under load expressed as a physiological saline absorption capacity under a load of 1.96 kPa in a local area of 78.5 mm2 is at least 10 g/g. This water-absorbent resin has excellent absorption properties in a localized absorption area.

Abstract: Provided is a non-destructive method for evaluating the structure of a water-absorbing resin which can be advantageously used for controlling various properties of the water-absorbing resin. This non-destructive method for evaluating the structure of a water-absorbing resin involves non-destructively evaluating the structure of a water-absorbing resin through an X-ray computer tomographic technique, wherein the method comprises a step 1 for installing the water-absorbing resin to be evaluated on a test piece stage of an X-ray computer tomography device, a step 2 for performing X-ray computer tomography on the water-absorbing resin using the X-ray computer tomography device and acquiring tomographic image data of the water-absorbing resin, and a step 3 for analyzing the tomographic image data using image analysis software and obtaining a tomographic image of the water-absorbing resin.

Abstract: There is provided a water-absorbent resin that exhibits both high water absorbency and high water-discharge capacity. The water-absorbent resin of the present invention is a water-absorbent resin comprising a polymer of a water-soluble ethylenically unsaturated monomer, wherein when a cross-sectional image of the water-absorbent resin is observed using X-ray computed tomography, the water-absorbent resin has a ratio of the area of cavity portions (cavity area ratio) in the cross-sectional image of 5% or more, as calculated according to Equation (I): cavity area ratio [%]={total cross-sectional area of cavity portions (B) in the water-absorbent resin/(total cross-sectional area of resin portions (A) in the water-absorbent resin+total cross-sectional area of cavity portions (B) in the water-absorbent resin)}×100??(I).

Abstract: Provided is a water-absorbing resin that exhibits excellent absorption performance and a high permeation rate with respect to liquids to be absorbed, and that effectively reduces liquid leakages, even in an absorbent body using a large amount of the water-absorbing resin. The water-absorbing resin is formed from a polymer of a water-soluble ethylenically unsaturated monomer, and when a cross-sectional image of the water-absorbing resin obtained by X-ray computer tomography is observed, the ratio (cavity area ratio) as calculated by formula (I) of the area of cavity portions in the cross-sectional image is 2-10%. The liquid flow rate index as calculated by formula (II) when a physiological saline liquid column flow rate test is performed on the water-absorbent resin having a particle diameter of 250 to 500 ?m at 37° C. is 5-20.

Abstract: There is provided a water-absorbent resin that exhibits a high liquid-retention capacity under a load and a small amount of re-wet even when it is used in an absorbent material having a low proportion of hydrophilic fibers. A water-absorbent resin comprising a polymer of a water-soluble ethylenically unsaturated monomer, wherein when a cross-sectional image of the water-absorbent resin is observed using X-ray computed tomography, the water-absorbent resin has a ratio of the area of cavity portions (cavity area ratio) in the cross-sectional image of 10% or less, as calculated according to Equation (I): cavity area ratio [%]={total cross-sectional area of cavity portions (B) in the water-absorbent resin/(total cross-sectional area of resin portions (A) in the water-absorbent resin+total cross-sectional area of cavity portions (B) in the water-absorbent resin)}×100??(I).

Abstract: Provided is a water-absorbent resin that quickly absorbs water, even in sandbag in which a large amount of the water-absorbent resin has been used, that does not easily form unswollen lump, and that has a high gel swelling volume when water is used to swell the water-absorbent resin. This water-absorbent resin is configured from a polymer of water-soluble ethylenic unsaturated monomers. The physiological-saline absorption capacity of the water-absorbent resin is 40-60 g/g. When a cross-sectional image of the water-absorbent resin is observed by x-ray computed tomography, the fraction of the area of the cross-sectional image that is hollow portions (the hollow area ratio of the cross-sectional image), as calculated on the basis of formula (I), is no more than 10%.

Abstract: There is disclosed a method for producing water-absorbent resin particles, comprising a polymerization step that includes mixing an oily liquid comprising a hydrocarbon dispersing medium and a surfactant, and an aqueous liquid comprising an aqueous solvent and a water-soluble ethylenically unsaturated monomer, forming a suspension comprising an oily liquid and an aqueous liquid dispersed in the oily liquid, and polymerizing the water-soluble ethylenically unsaturated monomer in the suspension. The HLB of the surfactant is 6 or greater, and the temperature of the suspension is kept at 35° C. or higher during the period from initial mixing of the oily liquid and aqueous liquid until complete mixing of the entire amounts.

Abstract: Disclosed is a water-absorbent resin particle in which the water-absorption rate of physiological saline is 1 second to 15 seconds, the median particle size is 100 ?m to 600 ?m, and the residual volatile component content is 1.5% by weight or less.

Abstract: There is disclosed a method for producing water-absorbent resin particles comprising a step that includes reversed-phase suspension polymerization of a water-soluble ethylenically unsaturated monomer in a suspension containing a surfactant that comprises a surfactant that comprises a fatty acid ester of sorbitan or sorbitol, or derivative thereof, and a hydrocarbon dispersion medium. The fatty acid ester includes a lauric acid ester and at least one kind of other ester selected from the group consisting of palmitic acid esters, stearic acid esters and behenic acid esters. The proportion of the peak area for lauric acid ester is 30-60%, based on the total peak area for fatty acid esters in the GPC chromatogram obtained from the fatty acid esters, and the proportion of the total peak area for other ester is 10-50%.

Abstract: An ECU calculates the thermal margins of the in-wheel motors, on the basis of the thermal capacities of the in-wheel motors, the allowable limit temperatures, and the motor temperatures. Next, the ECU distributes the total requested torque between the requested torques for each wheel using the percentages of the thermal margins. The ECU controls the operation of an inverter such that the in-wheel motors generate the requested torques for the wheels. Thus, the four in-wheel motors generate uniform amounts of heat.

Abstract: There is disclosed a method for producing water-absorbent resin particles comprising a step that includes reversed-phase suspension polymerization of a water-soluble ethylenically unsaturated monomer in a suspension containing a surfactant that comprises a surfactant that comprises a fatty acid ester of sorbitan or sorbitol, or derivative thereof, and a hydrocarbon dispersion medium. The fatty acid ester includes a lauric acid ester and at least one kind of other ester selected from the group consisting of palmitic acid esters, stearic acid esters and behenic acid esters. The proportion of the peak area for lauric acid ester is 30-60%, based on the total peak area for fatty acid esters in the GPC chromatogram obtained from the fatty acid esters, and the proportion of the total peak area for other ester is 10-50%.

Abstract: The present invention provides a method for producing water-absorbent resin particles which show an excellent water absorption rate and high equilibrium swelling capacity and which have an appropriate particle size to be excellent in handleability, and water-absorbent resin particles obtained by the method.

Abstract: The present invention provides a method for producing water-absorbent resin particles which show an excellent water absorption rate and high equilibrium swelling capacity and which have an appropriate particle size to be excellent in handleability, and water-absorbent resin particles obtained by the method.

Abstract: An ECU calculates the thermal margins of the in-wheel motors, on the basis of the thermal capacities of the in-wheel motors, the allowable limit temperatures, and the motor temperatures. Next, the ECU distributes the total requested torque between the requested torques for each wheel using the percentages of the thermal margins. The ECU controls the operation of an inverter such that the in-wheel motors generate the requested torques for the wheels. Thus, the four in-wheel motors generate uniform amounts of heat.

Abstract: There is disclosed a method for producing water-absorbent resin particles, comprising a polymerization step that includes mixing an oily liquid comprising a hydrocarbon dispersing medium and a surfactant, and an aqueous liquid comprising an aqueous solvent and a water-soluble ethylenically unsaturated monomer, forming a suspension comprising an oily liquid and an aqueous liquid dispersed in the oily liquid, and polymerizing the water-soluble ethylenically unsaturated monomer in the suspension. The HLB of the surfactant is 6 or greater, and the temperature of the suspension is kept at 35° C. or higher during the period from initial mixing of the oily liquid and aqueous liquid until complete mixing of the entire amounts.

Abstract: Disclosed is a water-absorbent resin particle in which the water-absorption rate of physiological saline is 1 second to 15 seconds, the median particle size is 100 ?m to 600 ?m, and the residual volatile component content is 1.5% by weight or less.