Abstract: [Problem] To provide a particulate water-absorbing agent that can significantly reduce re-wet even when pressure is applied to the particulate water-absorbing agent from the outside when the particulate water-absorbing agent is in a swollen state. [Solution] A particulate water-absorbing agent comprising a surface-crosslinked polyacrylic acid (salt)-based water-absorbing resin as a main component and satisfying the following expression (1). AAP(2.06 kPa)+RCAP(2.06 kPa)?0.58×CRC+55.6??(1), wherein AAP (2.06 kPa) represents absorption capacity (g/g) under a pressure of 2.06 kPa, RCAP (2.06 kPa) represents retention capacity against pressure after swelling (g/g), and CRC represents absorption capacity without pressure (g/g).

Abstract: Provided are a water-absorbing resin having more excellent balance of fluid retention capacity, liquid permeability, and low dustiness and a novel measurement method which enables evaluation of excellent physical properties of the water-absorbing resin. A method for measuring an absorption speed of a particulate water-absorbing agent is a method including the step of applying pressure to a portion of a bottom surface of a measurement container (51) by use of a flat plate (52) in a state in which part or whole of the particulate water-absorbing agent (56) is fixed on the bottom surface of the measurement container (51), the bottom surface being surrounded by a frame, introducing an aqueous solution through a liquid injection inlet (54) with which the flat plate (52) is equipped, and then measuring the amount of time elapsed until an end of absorption of the introduced aqueous solution by the particulate water-absorbing agent (56).

Abstract: Provided is a water-absorbing agent that causes no or little fluctuation of feed rate when fed with use of a feeder. A water-absorbing agent containing a water-absorbing resin as a main component, the water-absorbing agent satisfying the following (a) and (b): (a) K-index is 70 or more; and (b) Moisture absorption blocking ratio, after 30 minutes of standing at a temperature of 25° C. and a relative humidity of 80% RH, is 70 weight % or less, the K-index being defined by the following equation: K-index=100?(?438+3.6×angle of repose+3.5×angle of difference+7.9×compressibility rate+290×bulk density (EDANA method)).

Abstract: [Problem] In an embodiment involving addition of a chelating agent in an upstream process of the process for production, such as the polymerization step, the residual ratio of the chelating agent in the final product, a particulate water-absorbing agent, is improved. [Solution] A particulate water-absorbing agent having a poly(meth)acrylic acid (salt)-based water-absorbing resin as a main component, containing a chelating agent having a nitrogen atom and an inorganic reducing agent having a sulfur atom, wherein the particulate water-absorbing agent has a chelating agent ratio of 0.8 to 1.

Abstract: A water absorbent agent having a high water absorption multiplying factor where stickiness after absorbing liquid can be reduced when used as a hygienic material is produce by a method for manufacturing the water absorbing agent. The method for manufacturing a water absorbent agent having a centrifuge retention capacity (CRC) of 30 g/g or greater, includes subjecting an aqueous solution of a monomer that includes an acrylic acid (salt) to a polymerization step, a drying step, and a surface cross-linking step, and a step for adding ?-hydroxycarboxylic acid (salt) before the drying step. The atomic weight of the soluble portion eluted when the water absorbent agent absorbs liquid and swells can be reduced by the ?-hydroxycarboxylic acid (salt) before the drying step to reduce the stickiness of the water absorbent agent after absorption of liquid, which leads to discomfort during use of disposable diapers and the like.

Abstract: It is an object of the present invention to provide a novel water-absorbing sheet that can meaningfully reduce the return amount even when introduction of a liquid occurs intermittently for several times (particularly, three or more times) under a situation with no load, and the amount of introduction of the liquid becomes large.

Abstract: The present invention provides polyacrylic acid (salt)-based water-absorbing resin powder having an excellent fluid retention capacity under pressure, an excellent water absorption speed, and an excellent liquid permeability and a method for producing the polyacrylic acid (salt)-based water-absorbing resin powder. The earlier-described objects are attained by: a method for producing water-absorbing resin powder which includes adding an inorganic compound to a crosslinked hydrogel polymer obtained in a polymerization step of polymerizing a polyacrylic acid (salt) and performing crushing in specific gel-crushing conditions; and the resultant water-absorbing resin powder.

Abstract: To provide a water-absorbing resin composition having both a high centrifuge retention capacity (CRC) and a sufficient urine resistance and a method for producing such a water-absorbing resin composition, an aspect of the present invention is a water-absorbing resin composition having the following properties: (1) A centrifuge retention capacity (CRC) being not less than 35 g/g; (2) A post-degradation-test one-hour eluted soluble component being not more than 19% by mass; (3) An absorbency against pressure 0.7 psi (AAP0.7) being not less than 10 g/g; and (4) A content of a water-absorbing resin in dust being not more than 300 ppm with respect to a total mass of the water-absorbing resin composition.

Abstract: A method for filling a particulate water absorbing agent includes a filling step of filling a particulate water absorbing agent into a filling container and a vibrating step of vibrating the filling container at the outside of the filling container, the vibrating step being conducted at least one time between the start and the end of the filling step, in which a vibration condition in the vibrating step satisfies the following conditions (a) and (b):(a) vibration by a vibrating body in contact with the filling container has a vertical directional component and a vibrational angle is within 90°±30°; and (b) total amplitude at no load and a vibration frequency at no load of the vibrating body are set so as to satisfy Equation 1-1 and Equation 2 or Equation 1-2 and Equation 2.

Abstract: An embodiment of the present invention provides a water-absorbing sheet which, with respect to urine having a wide range of salt concentrations (mass %) including 0, has a favorable liquid absorption speed and favorable re-wet, and which has good comfortability for users, including infants, whose urine tends to change in salt concentration due to a change in the user's physical condition. In a water-absorbing sheet (10), a first particulate water-absorbing agent (12a) and a second particulate water-absorbing agent (12b) are localized, the first particulate water-absorbing agent (12a) has a gel permeation rate (GPR) which differs by 10 or more from that of the second particulate water-absorbing agent (12b), and the gel permeation rate of the second particulate water-absorbing agent (12b) is 50 or less.

Abstract: Provided is a water-absorbing agent that causes no or little fluctuation of feed rate when fed with use of a feeder. A water-absorbing agent containing a water-absorbing resin as a main component, the water-absorbing agent satisfying the following (a) and (b): (a) K-index is 70 or more; and (b) Moisture absorption blocking ratio, after 30 minutes of standing at a temperature of 25° C. and a relative humidity of 80% RH, is 70 weight % or less, the K-index being defined by the following equation: K-index=100?(?438+3.6×angle of repose+3.5×angle of difference+7.9×compressibility rate+290×bulk density (EDANA method)).

Abstract: Provided are a water-absorbing resin having more excellent balance of fluid retention capacity, liquid permeability, and low dustiness and a novel measurement method which enables evaluation of excellent physical properties of the water-absorbing resin. A method for measuring an absorption speed of a particulate water-absorbing agent is a method including the step of applying pressure to a portion of a bottom surface of a measurement container (51) by use of a flat plate (52) in a state in which part or whole of the particulate water-absorbing agent (56) is fixed on the bottom surface of the measurement container (51), the bottom surface being surrounded by a frame, introducing an aqueous solution through a liquid injection inlet (54) with which the flat plate (52) is equipped, and then measuring the amount of time elapsed until an end of absorption of the introduced aqueous solution by the particulate water-absorbing agent (56).

Abstract: Provided is a water-absorbing agent which is less likely to cause gel blocking and is suitable for a sanitary product and an absorbent article each being thin and containing a large amount of a water-absorbing agent, and which, while maintaining or hardly losing the other physical properties (a fluid retention capacity and a bulk specific gravity) of the water-absorbing agent, simultaneously achieves a high water absorbing speed (e.g., FSR), a high fluid retention capacity under load, high liquid permeability, and salt tolerance. The water-absorbing agent is a polyacrylic acid (salt)-based water-absorbing agent whose surface and its vicinity are crosslinked by an organic surface crosslinking agent, characterized by satisfying the following (A)-(D): (A) Free Swell Rate (FSR) of at least 0.

Abstract: The present invention provides polyacrylic acid (salt)-based water-absorbing resin powder having an excellent fluid retention capacity under pressure, an excellent water absorption speed, and an excellent liquid permeability and a method for producing the polyacrylic acid (salt)-based water-absorbing resin powder. The earlier-described objects are attained by: a method for producing water-absorbing resin powder which includes adding an inorganic compound to a crosslinked hydrogel polymer obtained in a polymerization step of polymerizing a polyacrylic acid (salt) and performing crushing in specific gel-crushing conditions; and the resultant water-absorbing resin powder.

Abstract: Provided is a water absorbent resin that is useful to sanitary materials such as a disposable diaper, a sanitary napkin, and a blood absorbent for medical use each having a higher liquid permeability and a higher water absorbing speed. Further provided is a water absorbent resin powder that is useful to sanitary materials such as a disposable diaper, a sanitary napkin, and a blood absorbent for medical use each having increased in absorbency of a liquid and in heat retaining property. A gel grinding device to be used to produce a water absorbent resin, includes: a screw; a feed opening; an extrusion opening; a porous plate; and a barrel, the barrel including a return preventing member provided on an inner surface thereof, and the return preventing member satisfying at least one of specific parameters.

Abstract: The present invention provides polyacrylic acid (salt)-based water-absorbing resin powder having an excellent fluid retention capacity under pressure, an excellent water absorption speed, and an excellent liquid permeability and a method for producing the polyacrylic acid (salt)-based water-absorbing resin powder. The earlier-described objects are attained by: a method for producing water-absorbing resin powder which includes adding an inorganic compound to a crosslinked hydrogel polymer obtained in a polymerization step of polymerizing a polyacrylic acid (salt) and performing crushing in specific gel-crushing conditions; and the resultant water-absorbing resin powder.

Abstract: An object of the invention is to provide a technique in which a decrease in physical properties is suppressed or consumer complaints are diminished. A method includes a filling step of filling a particulate water absorbing agent into a filling container and a vibrating step of vibrating the filling container at the outside of the filling container, the vibrating step being conducted at least one time between the start and the end of the filling step. A vibration condition in the vibrating step satisfies the following conditions: (a) vibration by a vibrating body in contact with the filling container has a vertical directional component and a vibrational angle is within 90°±30°; and (b) total amplitude at no load and a vibration frequency at no load of the vibrating body are set so as to satisfy Equation 1-1 and Equation 2 or Equation 1-2 and Equation 2.

Abstract: The purpose of the present invention is to provide a particulate water absorbing agent having both a high water absorption multiplying factor and a high water absorption rate and a method for manufacturing the same. The present invention is a particulate water absorbing agent for which CRC is 30 to 50 g/g, wherein the weight average particulate diameter (D50) is 200-600 ?m, and the DRC index given by the following formula is a specific value (for example, 43, 30, or 20) or less: DRC index=(49?DRC5min [g/g])/(D50 [?m]/1000).

Abstract: An object of the invention is to provide a technique in which a decrease in physical properties is suppressed or consumer complaints are diminished. A method for filling a particulate water absorbing agent includes a filling step of filling a particulate water absorbing agent into a filling container and a vibrating step of vibrating the filling container at the outside of the filling container, the vibrating step being conducted at least one time between the start and the end of the filling step, in which a vibration condition in the vibrating step satisfies the following conditions (a) and (b): (a) vibration by a vibrating body in contact with the filling container has a vertical directional component and a vibrational angle is within 90°±30°; and (b) total amplitude at no load and a vibration frequency at no load of the vibrating body are set so as to satisfy Equation 1-1 and Equation 2 or Equation 1-2 and Equation 2.

Abstract: The present invention provides a water-absorbing sheet suitable for a hygienic material such as a disposable diaper. The water-absorbing sheet in accordance with an aspect of the present invention includes: a first base material; a second base material; and a particulate water-absorbing agent sandwiched between the first base material and the second base material, at least one of the first base material and the second base material being a water-permeable base material, and at least part of the particulate water-absorbing agent satisfying the following physical properties (1), (2), and (3): (1) a centrifuge retention capacity (CRC) is 30 g/g to 50 g/g; (2) a mass average particle diameter (D50) is 200 ?m to 600 ?m; and (3) a DRC index defined by the following Formula (a) is 43 or less: DRC index=(49?DRC5 min)/(D50/1000)?? Formula (a).