Abstract: A particulate water-absorbent agent containing a polyacrylate salt-type water-absorbent resin. The agent has an absorption capacity without load of 28 g/g or higher and has a diffusion absorption index of 1.40 to 10.0 g/g min. The amount of water-soluble components in the agent, with stirring, is 15-60% by mass. The difference between this amount and the amount of water-soluble components, without stirring, is 15-50% by mass. Also disclosed is a method of making the above-identified agent.

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 present invention provides a surface treatment method for a water-absorbing resin comprising three steps of: 1) a humidifying and mixing step for mixing a base polymer and a surface cross-linking agent solution to obtain a “humidified substance”; 2) a pretreatment step for raising temperature of said humidified substance to obtain a “pretreated substance”; and 3) a surface cross-linking reaction step for cross-linking said pretreated substance to obtain a surface cross-linked “water-absorbing resin”; wherein dew point in the pretreatment step of the above 2) is from 50° C. to 95° C., and temperature of said humidified substance is raised from temperature below the dew point up to a temperature of 10° C. higher than the dew point.

Abstract: The present invention provides a surface treatment method for a water-absorbing resin comprising three steps of: 1) a humidifying and mixing step for mixing a base polymer and a surface cross-linking agent solution to obtain a “humidified substance”; 2) a pretreatment step for raising temperature of said humidified substance to obtain a “pretreated substance”; and 3) a surface cross-linking reaction step for cross-linking said pretreated substance to obtain a surface cross-linked “water-absorbing resin”; wherein dew point in the pretreatment step of the above 2) is from 50° C. to 95° C., and temperature of said humidified substance is raised from temperature below the dew point up to a temperature of 10° C. higher than the dew point.

Abstract: A particulate water-absorbent agent containing a polyacrylate salt-type water-absorbent resin. The agent has an absorption capacity without load of 28 g/g or higher and has a diffusion absorption index of 1.40 to 10.0 g/g min. The amount of water-soluble components in the agent, with stirring, is 15-60% by mass. The difference between this amount and the amount of water-soluble components, without stirring, is 15-50% by mass. Also disclosed is a method of making the above-identified agent.

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: An object of the present invention is to provide an excellent process for production of a surface-treated particulate water-absorbent resin wherein the process adopts a surface-treatment process that can enhance the properties (which the water-absorbent resin is desired to have) to extremely high levels, and also can solve the prior problems in such as safety, and further can sufficiently carry out the treatment even at a reaction temperature near room temperature. As a means of achieving this object, the process according to the present invention for production of a surface-treated particulate water-absorbent resin is characterized by comprising the steps of: adding a treating liquid to a particulate water-absorbent resin as a base polymer, wherein the treating liquid contains a radically polymerizable compound; and then irradiating the particulate water-absorbent resin with active energy rays while fluidizing the particulate water-absorbent resin, thereby surface-treating it.

Abstract: An object of the present invention is to provide an excellent process for production of a surface-treated particulate water-absorbent resin wherein the process adopts a surface-treatment process that can enhance the properties (which the water-absorbent resin is desired to have) to extremely high levels, and also can solve the prior problems in such as safety, and further can sufficiently carry out the treatment even at a reaction temperature near room temperature. As a means of achieving this object, the process according to the present invention for production of a surface-treated particulate water-absorbent resin is characterized by comprising the steps of: adding a treating liquid to a particulate water-absorbent resin as a base polymer, wherein the treating liquid contains a radically polymerizable compound; and then irradiating the particulate water-absorbent resin with active energy rays while fluidizing the particulate water-absorbent resin, thereby surface-treating it.

Abstract: A method of manufacturing an inner lined pipe in which a lining layer is formed to the inner circumferential surface of a pipe using a centrifugal molding method, wherein a resin mortar material and a hardening agent for lining are mixed at the top end of an arm member of a supply device and discharged, thereby enabling to select a lining material of a short pot life to attain efficient production, as well as eliminate wasteful consumption of the lining material.

Abstract: A centrifugal molding method which can smooth the inner surface of the resin concrete layer of a resin concrete pipe or of a composite pipe having a resin concrete layer even without using any special sand conditioning mechanism and which is high in productivity includes producing a composite pipe having a resin concrete layer or producing a resin concrete pipe by moving an arm member of a pipe material feeding device forward and backward axially through a pipe forming outer mold rotating about an axis thereof and by feeding pipe materials from a discharge port formed in a front end of the arm member. The resin concrete layer is formed by feeding resin and aggregate to a mixing portion provided at the front end of the arm member through separate feed routes, mixing the two in the mixing portion and discharging the resulting mixed resin concrete material from the discharge port.