Abstract: An embodiment of the present invention allows for production, with a high productivity, of a water-absorbent resin including an improved relationship between absorption capacity and water-soluble polymer which are conflicting properties of the water-absorbent resin, being easily controlled for polymerization reaction, being of no odor, being less colored, and being of high absorption properties. In one embodiment of the present invention, acrylic acid composition is neutralized with a basic composition including an iron content of 0.2 to 5 ppm by weight (relative to a basic compound exclusive of a solvent); and then polymerizing a resultant neutralized product, the acrylic acid composition including: (i) a methoxyphenol content of 10 to 200 ppm by weight relative to the weight of acrylic acid; and (ii) at least one compound content of which is 0 to 10 ppm by weight relative to the weight of acrylic acid, the compound being selected from the group consisting of protoanemonin and furfural.

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: To improve the heat retention by diapers and other absorbents, a heat retention indicator 1 of a water-absorbing resin which is defined in the present invention needs be 3.0° C./min or less and also that particular requirements need be met to satisfy this condition. If the requirements are met, a water-absorbing resin, absorbent, and absorbent article can be provided which has a heat retention indicator 1 of 0 to 3.0° C./min or less and which exhibits excellent heat retention and absorption.

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 purpose of the present invention is to improve the water absorption of a water-absorbent resin without sacrificing the productivity, production cost, safety, and so on. Provided is a sustainable and renewable water-absorbent resin with excellent whiteness, which is suitable for mass consumption as disposal diapers or the like, and which can dispense with excessive purification of raw material acrylic acid. Also provided is a process for the production of a water-absorbent resin, which comprises: a step of preparing acrylic monomers; a step of polymerizing the monomers; and a step of drying the obtained aqueous gel, wherein the monomers at the time of polymerization contain at least 400 ppm of propionic acid.

Abstract: From a viewpoint 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 solu

Abstract: A method includes the steps of: adding an organic surface cross-linking agent to a water absorbent resin having a cross-linked structure; adding a liquid permeability improving agent to the water absorbent resin concurrently with or after the addition of the organic surface cross-linking agent; and then adding a lubrication improving agent to the water absorbent resin. This provides a particulate water absorbing agent and a method for producing it, the particulate water absorbing agent being suitable for pneumatic transportation, suffering no decrease in the effect of the liquid permeability improving agent, and excelling in properties such as fluidity and damage resistance after the pneumatic transportation.

Abstract: Provided is a method for producing a polyacrylic acid (salt)-based water absorbent resin, which is a convenient production method for a water absorbent resin for an absorbent suitable for practical use, the water absorbent resin having a reduced amount of residual monomers.

Abstract: A method of producing a water-absorbent resin of the present invention reduces amounts of a residual cross-linking agent and a residual surfactant, achieves high productivity, and improves physical properties of the resultant water-absorbent, such as absorption capacity, extractable polymer content, powder friction, and gel crushability. The method includes the steps of: polymerizing an aqueous monomer solution containing as a major component an acrylic acid monomer in the presence of a cross-linking agent; and drying the resultant polymer by heating, in which the cross-linking agent is a multifunctional (meth)acrylate cross-linking agent having polyethylene glycol structural units including a total of 6 to 200 ethylene oxide repeating units, and the aqueous monomer solution includes a mono(meth)acrylate compound having polyethylene glycol structural units in an amount of 0.1 to 30% by weight relative to an amount of the multifunctional (meth)acrylate cross-linking agent.

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 method for producing a water-absorbing resin powder. The method includes a polymerization step, a drying step, a pulverization step, a classification step, and a surface cross-linking step. It further includes an additional step, performed before the surface cross-linking step, in which at least part of the classified polymer is supplied again to the same or a different pulverization step. The circulation pulverization ratio in the pulverization step is higher than 1.50.

Abstract: Objects of the present invention are: to provide a water-absorbent resin which exhibits excellent balances between water absorption performances; and further to provide a process by which a water-absorbent resin having excellent absorption properties can be produced even if no hydrophilic organic solvent is used, or even if its amount is extremely reduced, when carrying out the surface-crosslinking treatment; and further to provide a water-absorbent resin optimum to absorbent articles such as diapers.

Abstract: As a characteristic that had not been known conventionally at all, “permeability potential under pressure (PPUP)” of a particulate water absorbing agent is regulated, and further, “range of particle size distribution” and “coloring” are concomitantly regulated. The present invention is directed to a particulate water absorbing agent having the following (a) to (c): (a) permeability potential under pressure (PPUP) being 50 to 100%; (b) yellowness index (YI) being 0 to 10, and rate of change of yellowness index (?YI) being 100 to 150% following a coloring acceleration test for 14 days at 70±1° C. and the relative humidity of 95±1%; and (c) particles of smaller than 150 ?m specified by standard sieve classification accounting for 0 to 5% by weight, weight average particle diameter (D50) being 200 to 550 ?m, and logarithmic standard deviation (??) of particle size distribution being 0.20 to 0.40.

Abstract: Provided is a method which does not require alteration of the raw materials or high capital investment, and improves and stabilizes the physical property (for example, liquid permeability) of a water absorbent resin by means of a simple technique. A method for producing a water absorbent resin is disclosed, which method includes a polymerization step of polymerizing an aqueous solution of acrylic acid (salt) to obtain a water-containing gel-like crosslinked polymer; a drying step of drying the water-containing gel-like crosslinked polymer to obtain a water absorbent resin powder; a classification step of classifying the water absorbent resin powder; and a surface crosslinking step of surface crosslinking the water absorbent resin powder, wherein in the classification steps that are carried before the surface crosslinking step and/or after the surface crosslinking step, the stretch tension (tension) of the metal sieve mesh used in the classification step is from 35 [N/cm] to 100 [N/cm].

Abstract: A method for the production of a water-absorbing resin is to be provided which permits enhancement and stabilization of property, for example, liquid permeability, of a water-absorbing resin by a simple and convenient method without requiring change of raw materials or expensive facility investment. The method comprises a polymerization step for polymerizing an aqueous solution of acrylic acid (or salt thereof) to obtain a hydrogel cross-linked polymer; a drying step for drying the hydrogel cross-linked polymer to obtain a water-absorbing resin powder; a classification step for classifying the water-absorbing resin powder; and a surface cross-linking step for surface cross-linking the water-absorbing resin powder before or after the classification step, wherein electricity is eliminated in the classification step.

Abstract: A water absorbent resin having less fine powder or powdery dust and a controlled particle size is provided, and the water absorption rate of the water absorbent resin is increased by a simple method at low cost, while maintaining or improving other physical properties such as liquid permeability.

Abstract: [PROBLEM] To obtain a particulate water absorbent having excellent and stabilized physical properties.

Abstract: There is provided a production method for a water-absorbing resin for stably and continuously producing the water-absorbing resin with industrially high property, in particular, the water-absorbing resin with high liquid permeation. A method of the present invention relates to a production method for a water-absorbing resin including: a polymerization step of an aqueous solution of an unsaturated monomer; a drying step of the resultant hydrogel polymer; and a surface cross-linking step after drying; characterized by including a pneumatic transportation step for pneumatic transporting the water-absorbing resin powder substance in a pipeline with a surface roughness (Rz) of the inner surface of equal to or smaller than 800 nm, by using gas with a dew point of ?5° C. to ?100° C.

Abstract: A method of enhancing and stabilizing the physical property (for example, liquid permeability) of a water absorbent resin by means of a simple technique without requiring any alteration of the raw materials or high capital investment, is provided. Disclosed is a method for producing a water absorbent resin, which includes a polymerization step of polymerizing an aqueous solution of acrylic acid (salt) to obtain a water-containing gel-like crosslinked polymer; a drying step of drying the water-containing gel-like crosslinked polymer, to obtain a water absorbent resin powder; a classification step of classifying the water absorbent resin powder; and a surface crosslinking step of surface crosslinking the water absorbent resin powder, wherein in the classification step that is carried out before the surface crosslinking step and/or after the surface crosslinking step, a tapping material is installed below the metal sieve mesh used in the classification step, and thereby classification is carried out.

Abstract: A polyacrylic acid (salt), or a polyacrylic acid (salt)-based water-absorbing resin, contains a tracer for detecting various troubles in the water-absorbing resin during the period from the production of the water-absorbing resin to the use and discard thereof by a consumer. The polyacrylic acid (salt)-based water-absorbing resin has a stable carbon isotope ratio, as determined by accelerator mass spectrometry, of less than ?20% and a radioactive carbon content of 1.0×10?14 or mole. The polyacrylic acid (salt)-based water-absorbing resin has: a CRC of 10 [g/g] or mole; an AAP of 20 [g/g] or mole; an Ext of 35 wt. % or less; a content of residual monomers of 1,000 ppm or less; a PSD in which the proportion of particles having a particle diameter of 150 ?m or larger but less than 850 ?m is 90 wt. % or more; and an FSR of 0.15 [g/g/s] or more.