Abstract: The subject invention provides a hydrophilic polymer (water-absorbing resin) which is superior in performance and productivity. According to the production method of the present invention, a hydrophilichigh-molecular-weight compound is dispersed in an aqueous solution containing a hydrophilic monomer. The dispersed hydrophilic high-molecular-weight compound is dissolved by heat of neutralization (heat of hydration) and/or heat of polymerization generated in the process of producing a hydrophilic polymer.

Abstract: A method for surface crosslinking water-absorbing resin of the present invention includes a step (1) of obtaining a wet mixture, a step (2) of obtaining a dried particulate composition, and a step (3) of carrying out a surface crosslinking reaction. With this, since a processing time of each step becomes short, it is possible to mass produce the water-absorbing resin having excellent physical properties. Moreover, a method for manufacturing the water-absorbing resin of the present invention includes a modifying step and a cooling step. The modifying step and/or the cooling step are/is carried out by using stirring means including a rotation axis having a plurality of stirring boards, and the stirring means includes the stirring board having a specific thickness and/or a scraping blade having a specific shape. With this, it is possible to suppress the generation of the fine powder in the modifying step and/or the cooling step.

Abstract: An object of the present invention is to provide a water absorbent having excellent gel properties and showing excellent properties when used in a water-absorbing material of a sanitary/hygienic material such as paper diaper. Moreover, another object of the present invention is to provide a water absorbent which is safe and excellent in liquid permeability, and in which an amount of liquid permeability improver for improving the liquid permeability is reduced. The water absorbent is made from a water-absorbing resin prepared by a specific polymerization method and having a high degree of cross-linking, a high liquid holding property and a high gel strength (its swelling pressure of gel layer of is 35 kdyne/cm2 or more). This water absorbent is further processed to have a particular particle size distribution (95 wt % or more of its particles are less than 850ƒÊm but not less than 106ƒÊm, and logarithmic standard deviation (ƒĐƒÄ) is in a range of 0.25 to 0.

Abstract: A particulate water retaining material for cultivating plant comprising (A) a carboxyl group-containing water-insoluble water absorbent resin and (B) a polyvalent metal compound, by having the compound (B) deposited on the the rerin (A), it is made possible to possess an outstanding water absorbing property without impairing the growth of a plant.

Abstract: The subject invention produces a water-absorbent resin by carrying out stationary polymerization of an ethylenically-unsaturated monomer containing acrylic acid and/or acrylate; cutting the resulting hydrous gelatinous polymer; and drying the hydrous gelatinous polymer which mainly contains angular particles having 6 smooth planes. The resulting water-absorbent resin particles are not aggregate, and can be efficiently dried. By coating at least a part of the surface of each of the particles with an adhesion block agent before, after, and/or at the time of cutting process, the adhesion preventing effect further increases.

Abstract: The invention provides: a water-absorbent resin granule-containing composition with resolution of various problems, as caused by water-absorbent resin fine powders, and with high granulation strength, and with no physical property deterioration due to granulation, and, if anything, with improvement of the absorption capacity under a load by granulation; and a process for producing the above granule. A water-absorbent resin primary particle and a water-absorbent resin granule are separately surface-crosslinked and then mixed, or mixed and then surface-crosslinked. The granulation is carried out by mixing a preheated aqueous liquid and a water-absorbent resin powder at a high speed or by supplying a water-absorbent resin powder downstream of an aqueous liquid with a continuous extrusion mixer.

Abstract: The present invention provides a production process by which a water-absorbent resin of excellent quality can be obtained at a low cost by reasonable steps in aqueous solution polymerization. The process for producing a water-absorbent resin comprises the step of polymerizing an aqueous solution of water-absorbent resin-forming monomers including acrylic acid and/or its sodium salt as major components, wherein: (1) the aqueous solution has a monomer component concentration of not less than 45 weight %; (2) the polymerization is carried out while water is evaporated so that the ratio (concentration ratio) between a solid component concentration in a hydropolymer as formed by the polymerization and a solid component concentration in the aqueous monomer solution will not be less than 1.10; and (3) the solid component concentration in the hydropolymer as formed by the polymerization is not more than 80 weight %.

Abstract: According to the present invention, a balance between lowering of the fine powder generated during the production, and lowering of the amount of residual monomer in the resulting water absorbent resin can be achieved. More particularly, according to the present invention, a water absorbent resin which includes a small amount of residual monomer and has a favorable physical property can be obtained while effectively reutilizing the fine powder generated in the production step of the water absorbent resin, without increasing using amount of an additive (at least one selected from the group consisting of thermal initiators, oxidizing agents and reducing agents) for reducing the residual monomer. In other words, the method for production of a water absorbent resin of the present invention is a method in which the residual monomer can be efficiently reduced, and in addition, an effect in terms of the production cost, i.e.

Abstract: The present invention provides a production process by which a water-absorbent resin of excellent quality can be obtained at a low cost by reasonable steps in aqueous solution polymerization. The process for producing a water-absorbent resin comprises the step of polymerizing an aqueous solution of water-absorbent resin-forming monomers including acrylic acid and/or its sodium salt as major components, wherein: (1) the aqueous solution has a monomer component concentration of not less than 45 weight %; (2) the polymerization is carried out while water is evaporated so that the ratio (concentration ratio) between a solid component concentration in a hydropolymer as formed by the polymerization and a solid component concentration in the aqueous monomer solution will not be less than 1.10; and (3) the solid component concentration in the hydropolymer as formed by the polymerization is not more than 80 weight %.

Abstract: A production method of a water-absorbent resin includes the steps of: obtaining a hydrogel by supplying monomer liquid to a reaction device so that the monomer liquid is polymerized; and detaching the hydrogel from the reaction device, wherein the reaction device's surface in contact with the monomer liquid at a position where polymerization occurs is made of a fluororesin having a melt viscosity of less than 1×108 poise at 380° C. On this account, it is possible to obtain a water-absorbent resin having less amounts of an extractable content with high productivity and it is possible to carry out continuous production for an extended period of time.

Abstract: A method for the production of a water-absorbent agent comprises mixing an absorbent resin containing a carboxyl group with an additive soluble in the aqueous solution of at least one member selected from the group consisting of inorganic acids, organic acids, and polyamino acids and a cross-linking agent capable of reacting with the carboxyl group. A water-absorbent agent obtained by adding from 0.005 to 8 parts by weight of an epoxy compound to 100 parts by weight of a water-absorbent resin, exhibiting an absorption capacity without load of at least 45 (g/g), an absorption capacity under load of 20 g/cm2 of not less than 30 (ml/g) and having a residue amount of an epoxy compound of not more than 2 ppm. A water-absorbent composition comprises a polyamino acid (salt) and a water-absorbent resin containing a carboxyl group.

Abstract: A method for the production of a water-absorbent agent comprises mixing an absorbent resin containing a carboxyl group with an additive soluble in the aqueous solution of at least one member selected from the group consisting of inorganic acids, organic acids, and polyamino acids and a cross-linking agent capable of reacting with the carboxyl group. A water-absorbent agent obtained by adding from 0.005 to 8 parts by weight of an epoxy compound to 100 parts by weight of a water-absorbent resin, exhibiting an absorption capacity without load of at least 45 (g/g), an absorption capacity under load of 20 g/cm2 of not less than 30 (ml/g) and having a residue amount of an epoxy compound of not more than 2 ppm. A water-absorbent composition comprises a polyamino acid (salt) and a water-absorbent resin containing a carboxyl group.

Abstract: The present invention relates to a method for continuous production of a water-absorbent resin by use of an continuous polymerization device having a charge part of a monomer aqueous solution; an endless belt on which the monomer and a hydropolymer formed are conveyed; and a discharge part of the hydropolymer, wherein the continuous polymerization device has side walls and a ceiling, and the space ratio in the device represented by the equation, “space ratio in the device=B/A”, is in the range of 1.2 to 20. In the equation, A is a maximum cross-sectional area (cm2) of the hydropolymer during the polymerization in the width direction of the endless belt, and B is a maximum cross-sectional area (cm2) of the space between the endless belt of the continuous polymerization device and the ceiling of the continuous polymerization device in the width direction of the endless belt.

Abstract: A particulate water absorbing agent of the present invention includes a water absorbent resin, having a cross-linking structure, whose surface has been cross-linked by adding a surface treatment agent, wherein: (i) a mass average particle diameter (D50) ranges from 200 to 600 ?m and 95 to 100 wt % of a particulate water absorbing agent whose particle diameter ranges from less than 850 ?m to not less than 150 ?m is contained with respect to 100 wt % of whole the particulate water absorbing agent, and (ii) a logarithmic standard deviation (??) of particle size distribution ranges from 0.25 to 0.45, and (iii) a compressibility rate defined by a following equation ranges from 0 to 18%, and (iv) a surface tension of a supernatant liquid obtained in 4 minutes after dispersing 0.5 g of the particulate water absorbing agent in 50 ml of physiological saline whose temperature is 20° C.

Abstract: The present invention provides a production process by which a water-absorbent resin of excellent quality can be obtained at a low cost by reasonable steps in aqueous solution polymerization. The process for producing a water-absorbent resin comprises the step of polymerizing an aqueous solution of water-absorbent resin-forming monomers including acrylic acid and/or its sodium salt as major components, wherein: (1) the aqueous solution has a monomer component concentration of not less than 45 weight %; (2) the polymerization is carried out while water is evaporated so that the ratio (concentration ratio) between a solid component concentration in a hydropolymer as formed by the polymerization and a solid component concentration in the aqueous monomer solution will not be less than 1.10; and (3) the solid component concentration in the hydropolymer as formed by the polymerization is not more than 80 weight %.

Abstract: The present invention provides: a production process for a particulate water-absorbent resin with high productivity, which production process is carried out in such a manner that the particulate water-absorbent resin will contain particles with particle diameters of 150 to 850 ?m (but excluding 850 ?m) in an amount of not smaller than 75 weight % of the particulate water-absorbent resin after the pulverization step or after the pulverization step and the drying step even if the adjustment of the particle diameters is not carried out by the sieving classification procedure; a novel particulate water-absorbent resin having high properties; and a sanitary material comprising this particulate water-absorbent resin.

Abstract: The present invention provides such a production process that a low-cost water-absorbent resin having excellent quality can be obtained by reasonable steps in aqueous solution polymerization. The production process for a water-absorbent resin comprises a polymerization setup that includes the steps of: supplying an aqueous solution of a water-soluble unsaturated monomer component including a major proportion of acrylic acid and/or its salt into a polymerization vessel causing shearing action; and then carrying out polymerization, involving crosslinking, of the water-soluble unsaturated monomer and at the same time carrying out fine division of the resultant hydrogel; with the production process being characterized in that the aqueous solution of the water-soluble unsaturated monomer component as supplied into the polymerization vessel has a temperature of not lower than 40° C.

Abstract: The present invention provides a production process by which a water-absorbent resin of excellent quality can be obtained at a low cost by reasonable steps in aqueous solution polymerization. The process for producing a water-absorbent resin comprises the step of polymerizing an aqueous solution of water-absorbent resin-forming monomers including acrylic acid and/or its sodium salt as major components, wherein: (1) the aqueous solution has a monomer component concentration of not less than 45 weight %; (2) the polymerization is carried out while water is evaporated so that the ratio (concentration ratio) between a solid component concentration in a hydropolymer as formed by the polymerization and a solid component concentration in the aqueous monomer solution will not be less than 1.10; and (3) the solid component concentration in the hydropolymer as formed by the polymerization is not more than 80 weight %.

Abstract: An object of the present invention is to provide a particulate water-absorbent resin composition which is so excellent that: the absorption ability in an initial short time is secured in some degree, and further, the absorption capacity lastingly increases over a long period, and also the liquid permeability and the liquid diffusibility can be secured. As a means of achieving this object, a particulate water-absorbent resin composition according to the present invention is a particulate water-absorbent resin composition comprising a carboxyl-group-containing water-absorbent resin in an amount of not smaller than 80 mass %, with the composition being characterized by being: not less than 20 g/g in specific-particle-diameter absorption capacity under load (0.29 psi (2.00 kPa), 1 hour); and not less than 3 g/g in specific-particle-diameter absorption index increment in 20 hours.

Abstract: An object of the present invention is to make it possible, in order to form the fine powder of the water-absorbent resin into a water-absorbing material having particle diameters favorable for practical use, that a water-absorbing material which has high agglomeration strength and is excellent in the quality performances is obtained at a low cost with good efficiency without causing the problems of the adhesion to such as treatment apparatus.