Abstract: There are disclosed a water-absorbent resin composition and its production process, wherein the water-absorbent resin composition causes little gel-blocking and is excellent in the liquid permeability and liquid diffusibility and is high also in the absorption performances and further is strong also against the physical damage; and there are further disclosed a water-absorbent resin composition and its production process, wherein the water-absorbent resin composition has the following further advantages, in addition to the above, of involving little segregation of the metal compound and further having a dust prevention effect.

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.

Abstract: [PROBLEM] It is an object of the present invention to efficiently obtain efficiently a water-absorbent resin having excellent property. [SOLUTION] A production method for a water-absorbent resin, comprising: a polymerization step for obtaining hydrogel by subjecting a monomer aqueous solution to a polymerization reaction; and a drying step for drying the hydrogel; wherein drying in the drying step is performed using a continuous through-flow belt-type drying machine; solid content of the hydrogel supplied to the drying step is 35% by weight or more, and thickness variation rate (1) represented by the following EXPRESSION 1 of the hydrogel loaded onto through-flow belt in the continuous through-flow belt, is 1.05 to 5: [MATH. 1] Thickness variation rate (1)=(Maximum thickness of hydrogel in a width direction of the through-flow belt)/(Average thickness of hydrogel in a width direction of the through-flow belt).

Abstract: [PROBLEM] It is an object of the present invention to efficiently obtain efficiently a water-absorbent resin having excellent property. [SOLUTION] A production method for a water-absorbent resin, comprising: a polymerization step for obtaining hydrogel by subjecting a monomer aqueous solution to a polymerization reaction; and a drying step for drying the hydrogel; wherein drying in the drying step is performed using a continuous through-flow belt-type drying machine; pore opening rate of the through-flow belt in the continuous through-flow belt-type drying machine is 20 to 50%; solid content of the hydrogel supplied to the drying step is 35% by weight or more; and area occupancy rate of the hydrogel is 85 to 100% relative to the through-flow belt.

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 at 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: A process for producing a water absorbent resin is provided with which it is possible to efficiently and inexpensively obtain a surface-crosslinked water-absorbing resin having excellent material properties, while ensuring high productivity. In continuous production scaled up to a large scale (in particular, 1 t/hr or more), the physical properties are improved and stabilized (for example, a reduction in standard deviation of the physical properties) by a surface crosslinking treatment to further improve absorption against pressure (AAP) and saline flow conductivity (SFC).

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: In obtaining a water-absorbing resin with high property in high productivity, produced a production method for a water-absorbing resin in high property and stably. Provided is a production method for a water-absorbing resin, comprising: a step for polymerizing an acrylic acid aqueous solution; a step for drying the resultant water-containing gel; a step for pulverizing and classifying the dried substance; and a step for surface cross-linking after classification, wherein a hopper having an inclination angle of a cone part of equal to or larger than 45 degree, and a drawing rate of 30 to 80% is used.

Abstract: A production method of the present invention is a polyacrylic water-absorbent resin powder production method including the steps of: producing an acrylic monomer solution in which gas is dissolved and/or dispersed; polymerizing the acrylic 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 the step of polymerizing, fragmenting a hydrated gel crosslinked polymer obtained by polymerizing the acrylic monomer solution; and drying by heat the hydrated gel crosslinked polymer thus fragmented, the gas being dissolved and/or dispersed in the acrylic monomer solution by at least one of the methods (a) to (c): (a) applying pressure to the acrylic monomer solution and the gas; (b) creating swirling flows of the acrylic monomer solution and the gas; and (c) introducing the gas with the acrylic monomer solution via fine holes.

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: [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 method of transporting an absorbent resin powder, said method being suitable for long-distance transport, and being able to inhibit the deterioration of the properties of the absorbent resin powder while also inhibiting obstructions. During the manufacturing process, the absorbent resin powder is transported pneumatically via transport pipes. This transport method involves two or more air transport devices (A, B, C) within one transport section, and the air transport devices (A, B, C) are connected in series by transport pipes (P1, P2, P3).

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: 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: In obtaining a water-absorbing resin with high property in high productivity, produced a production method for a water-absorbing resin in high property and stably. Provided is a production method for a water-absorbing resin, comprising: a step for polymerizing an acrylic acid aqueous solution; a step for drying the resultant water-containing gel; a step for pulverizing and classifying the dried substance; and a step for surface cross-linking after classification, wherein a hopper having an inclination angle of a cone part of equal to or larger than 45 degree, and a drawing rate of 30 to 80% is used.

Abstract: A water-absorbing agent according to the present invention includes water-absorbent resin particles having an internal cross-linked structure, wherein a vicinity of a surface of the water-absorbent resin particle is cross-linked with a surface cross-linking agent, and the water-absorbent resin particle has therein a sea-island structure having (i) part containing a first water-soluble multivalent metal salt such as aluminum sulfate and (ii) part not containing the first water-soluble multivalent metal salt. With this arrangement, it is possible to provide a water-absorbing agent having less water-soluble component content, more excellent liquid permeability, and more excellent water retention under pressure than the conventional water-absorbing agent.

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: An object of the present invention is to make it possible that: a high-concentration hydrogel sheet, which is suitable for production of high-performance water-absorbent resin particles, is cut efficiently without involving the adhesion to such as cutting-blades; and the subsequent disintegration operation is also successfully carried out; and hydrogel particles excellent in the quality and performances are efficiently produced.

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.