Abstract: An object of the present invention is to provide a water absorbent resin powder for a heat-generating element composition, which suppresses the generation of the aggregates derived from the water absorbent resin and the adhesion of the water absorbent resin in the production of a heat-generating element composition. A present inventive water absorbent resin powder for a heat-generating element composition includes polyacrylic acid (salt)-based water absorbent resin powder which have a bulk specific gravity (specified by JIS K3362) of 0.630 g/cm3 or less, fluid retention capacity without load (CRC) for a 0.9% by weight aqueous solution of sodium chloride (specified by ERT441.01-2) of 32.0 g/g or less, a weight-average particle diameter (specified by sieve classification) of 250 ?m or more, and an amount of a residual glycidyl-based crosslinking agent of 10 ppm or less.

Abstract: An object of the present invention is to provide a water absorbent resin powder for a heat-generating element composition, which suppresses the generation of the aggregates derived from the water absorbent resin and the adhesion of the water absorbent resin in the production of a heat-generating element composition. A present inventive water absorbent resin powder for a heat-generating element composition includes polyacrylic acid (salt)-based water absorbent resin powder which have a bulk specific gravity (specified by JIS K3362) of 0.630 g/cm3 or less, fluid retention capacity without load (CRC) for a 0.9% by weight aqueous solution of sodium chloride (specified by ERT441.01-2) of 32.0 g/g or less, a weight-average particle diameter (specified by sieve classification) of 250 ?m or more, and an amount of a residual glycidyl-based crosslinking agent of 10 ppm or less.

Abstract: The present invention provides a novel acrylic acid crosslinked polymer and the use thereof. The present invention provides the acrylic acid crosslinked polymer in which the content of soluble components is 40 wt. % or higher. The present invention also provides a method for adjusting the viscosity of a fracturing fluid in a hydraulic fracturing method, the viscosity adjustment method including: A) a step of measuring the types and quantities of metal cations which are in water and which are the object of viscosity adjustment; B) a step of selecting the type and quantity of an acrylic acid crosslinked polymer on the basis of the types and quantities of metal cations and the pH so as to achieve a viscosity that is required for fracturing in a hydraulic fracturing method; and C) a step of adjusting the viscosity of the fracturing fluid using the acrylic acid crosslinked polymer of the selected type and quantity.

Abstract: [Object] To provide a method for stably producing a water-absorbent resin in powder form or particle form, which has excellent physical properties such as water absorption performance and the like, without any production trouble. [Solution] A method for producing a water-absorbent resin includes mixing a monomer composition, which contains at least a monomer and a pyrolytic polymerization initiator, with an organic solvent, a temperature of the organic solvent is not lower than 70° C. at time of mixing, and when a mass per unit time of the monomer in the monomer composition to be mixed with the organic solvent is expressed as an amount per unit volume of the organic solvent, a lower limit is 0.01 g/ml/min, and an upper limit is 0.2 g/ml/min.

Abstract: From a view pint of decreasing an out of spec product after surface crosslinking, particularly, when an alkylene carbonate compound is used as a surface crosslinking agent, influence due to an air temperature is great, and it is necessary to reduce ethylene glycol which is produced as a byproduct. There is provided a process for producing a polyacrylic acid (salt)-based water absorbent resin powder, comprising storing a non-polymerized organic compound being a raw material (modified raw material) of a water absorbent resin powder in a heated state, thereafter, mixing the non-polymerized organic compound with other compound at a predetermined ratio and, further, mixing the mixture into a water absorbent resin powder.

Abstract: The present invention provides a novel acrylic acid crosslinked polymer and the use thereof. The present invention provides the acrylic acid crosslinked polymer in which the content of soluble components is 40 wt. % or higher. The present invention also provides a method for adjusting the viscosity of a fracturing fluid in a hydraulic fracturing method, the viscosity adjustment method including: A) a step of measuring the types and quantities of metal cations which are in water and which are the object of viscosity adjustment; B) a step of selecting the type and quantity of an acrylic acid crosslinked polymer on the basis of the types and quantities of metal cations and the pH so as to achieve a viscosity that is required for fracturing in a hydraulic fracturing method; and C) a step of adjusting the viscosity of the fracturing fluid using the acrylic acid crosslinked polymer of the selected type and quantity.

Abstract: A water-absorbing resin composition including 100 parts by weight of water-absorbing resin particles and 0.01 to 1 part by weight of additive particles, wherein a percent by weight of the additive particles, (x [%]), based on 100% by weight of the water-absorbing resin particles in the composition, and weight ratio of free additive particles, (y), relative to the percent by weight, (x [%]), satisfy the following formula: 0.04(x)0.1?y?0.2(x)0.5.

Abstract: A particulate water absorbing agent of the present invention is a water absorbing agent containing a water absorbing resin as a main component, the particulate water absorbing agent containing a polyvalent metal cation and satisfying: (1) the polyvalent metal cation is contained in an amount between 0.001 wt % and 5 wt % relative to the amount of the water absorbing agent; (2) an absorbency without pressure (CRC) is not less than 28 (g/g) and an absorbency against pressure (AAP 4.83 kPa) is not less than 10 (g/g); (3) the absorbency against pressure and the absorbency without pressure satisfy 77 ?AAP (4.83 kPa)+1.8×CRC?100; and (4) a moisture content of the water absorbing agent is between 5 wt % and 20 wt %. This provides a water absorbing agent which has blocking resistance after moisture absorption, is excellent in stability to shock and suppresses Re-Wet when used in a diaper.

Abstract: [Object] To provide a method for stably producing a water-absorbent resin in powder form or particle form, which has excellent physical properties such as water absorption performance and the like, without any production trouble. [Solution] A method for producing a water-absorbent resin includes mixing a monomer composition, which contains at least a monomer and a pyrolytic polymerization initiator, with an organic solvent, a temperature of the organic solvent is not lower than 70° C. at time of mixing, and when a mass per unit time of the monomer in the monomer composition to be mixed with the organic solvent is expressed as an amount per unit volume of the organic solvent, a lower limit is 0.01 g/ml/min, and an upper limit is 0.2 g/ml/min.

Abstract: A method for producing a water absorbent resin, the method including a polymerization step, a drying step, a classification step, and a surface crosslinking step. The classification step carried out before or after the surface crosslinking step requires use of a tapping material and a metal sieve mesh, in which the tapping material being heated at 40° C. to 100° C. is installed below the metal sieve mesh, and the metal sieve mesh has an area of 1 to 10 m2/sheet. The classification step further requires introducing a classification aid particle, which has a specific gravity different from that of the water absorbent resin, to the metal sieve mesh; and monitoring the presence or absence of damage to the metal sieve mesh.

Abstract: The purpose of the present invention is to provide a method for producing a water absorbent resin in which a water absorbent resin having excellent properties can be obtained effectively.

Abstract: From a view point of reduction in an out of spec product after surface crosslinking, particularly, when an alkylene carbonate compound is used as a surface crosslinking agent, influence by an air temperature is great, and it is necessary to reduce ethylene glycol which is produced as a byproduct, and there is provided a process for producing a polyacrylic acid (salt)-based water absorbent resin powder, comprising a step of polymerizing an aqueous acrylic acid (salt)-based monomer solution, a step of drying the resulting polymer, an optional grinding•classifying step, and a surface crosslinking step, wherein in the surface crosslinking step, (1) a surface crosslinking agent containing an alkylene carbonate compound and a polyhydric alcohol compound is mixed into a water absorbent resin powder, the mixture is heat-reacted and, further, simultaneously with, or separately from the mixing, an ion reactive surface crosslinking agent is mixed, and/or (2) mixing treatment of mixing a surface crosslinking agent sol

Abstract: A method for producing a water absorbent resin, the method including a polymerization step, a drying step, a classification step, and a surface crosslinking step. The classification step carried out before or after the surface crosslinking step requires use of a metal sieve mesh having stretch tension from 35 to 100 N/cm, in which an air jet cleaner or an air jet brush cleaner and plural tapping balls or tapping blocks are installed below the metal sieve mesh, a classification aid particle having specific gravity different from that of the water absorbent resin powder is added, and a fine powder of the water absorbent resin and the classification aid particle are removed.

Abstract: A method for producing a polyacrylic water-absorbent resin powder includes the steps of: producing an acrylic monomer solution in which gas is dissolved and/or dispersed; polymerizing the monomer solution in the absence of a surface active agent or in the presence of not more than 300 ppm of a surface active agent; during or after polymerizing, fragmenting the resulting hydrated gel crosslinked polymer; and drying the fragmented hydrated gel crosslinked polymer. The gas is dissolved and/or dispersed in the monomer solution by (a) applying pressure to the acrylic monomer solution and the gas; (b) creating swirling flows of the acrylic monomer solution and the gas; or (c) introducing the gas with the acrylic monomer solution via fine holes. The production method efficiently produces a water-absorbent resin having an excellent water-absorption rate without deteriorating a liquid-absorbent property of a sanitary product or the like.

Abstract: [PROBLEM] Provided is a transportation method for a water-absorbing resin powder substance, which is capable of suppressing property decrease of the water-absorbing resin powder substance while suppressing blocking phenomenon and is suitable for long distance transportation. [SOLUTION] The present invention is a transportation method for a water-absorbing resin powder substance during a production step by pneumatic transportation via a transportation pipeline. In this transportation method, two or more pneumatic transportation apparatuses (A, B, C) are provided in one transportation section, and these pneumatic transportation apparatuses (A, B, C) are connected by the transportation pipelines (P1, P2, P3) in series.

Abstract: Disclosed is a method for producing a water absorbent resin, by which a surface-crosslinked water absorbent resin having excellent physical properties can be efficiently obtained at low cost, while assuring high productivity. When the production scale is increased to a continuous production on a huge scale (for example, 1 t/hr or more), the physical properties are improved and stabilized (for example, standard deviation of the physical properties is reduced) by a surface-crosslinking treatment, and the absorption against pressure (AAP) and liquid permeability (SFC) are further improved.

Abstract: [Problem] To provide a pneumatic conveyance method for a water-absorbing resin powder substance, which is capable of suppressing property decrease of the water-absorbing resin powder substance, while suppressing obstruction phenomenon. [Solution] A conveyance method for a water-absorbing resin powder substance by pneumatic conveyance of the water-absorbing resin powder substance during a production step via a transportation pipeline, wherein a variation of a solid-gas ratio (R1/R2) exceeds 1 and is equal to or smaller than 7, provided that R1 (kg-resin/kg-air) stands for an initial solid-gas ratio at a start point of the transportation pipeline, and R2 (kg-resin/kg-air) stands for a terminal solid-gas ratio at a terminal point of the transportation pipeline is provided.

Abstract: Provided is a production method for the particulate water-absorbing agent, which can collecting the fine powders generated during the producing process efficiently without worsening working environment, and also the particulate water-absorbing agent produced by the production method thereof. This production method includes (1) a polymerization step for obtaining a polymer gel, (2) a drying step for drying said polymer gel to obtain a particulate water-absorbing resin, (3) a classification step for sieving said particulate water-absorbing resin, (4) a surface cross-linking step for cross-linking the neighborhood of the surface of said particulate water-absorbing resin (5) a packaging step for filling a packaging material container with said particulate water-absorbing agent for packaging and (6) a transportation step for transporting the products produced in each of the steps to the other steps.

Abstract: A particulate water absorbing agent of the present invention is a water absorbing agent containing a water absorbing resin as a main component, the particulate water absorbing agent containing a polyvalent metal cation and satisfying: (1) the polyvalent metal cation is contained in an amount between 0.001 wt % and 5 wt % relative to the amount of the water absorbing agent; (2) an absorbency without pressure (CRC) is not less than 28 (g/g) and an absorbency against pressure (AAP 4.83 kPa) is not less than 10 (g/g); (3) the absorbency against pressure and the absorbency without pressure satisfy 77?AAP (4.83 kPa)+1.8×CRC?100; and (4) a moisture content of the water absorbing agent is between 5 wt % and 20 wt %. This provides a water absorbing agent which has blocking resistance after moisture absorption, is excellent in stability to shock and suppresses Re-Wet when used in a diaper.

Abstract: Disclosed is a method for producing a water absorbent resin, by which a surface-crosslinked water absorbent resin having excellent physical properties can be efficiently obtained at low cost, while assuring high productivity. When the production scale is increased to a continuous production on a huge scale (for example, 1 t/hr or more), the physical properties are improved and stabilized (for example, standard deviation of the physical properties is reduced) by a surface-crosslinking treatment, and the absorption against pressure (AAP) and liquid permeability (SFC) are further improved.