Nippon Shokubai Co., Ltd.

Shin-Ichi Fujino

Kunihiko Ishizaki

Yoshio Irie

Kazushi Torii

Kazuhiko Sakamoto

Kinya Nagasuna

Ryota Wakabayashi

Katsuyuki Wada

Motohiro Imura

Koji Honda

Yoshihiko Masuda

Yoshihiro Shobo

Mai Sato

Tokio Shuto

Shin-ya Katsube

Yorimichi Dairoku

Kenji Kadonaga

Hiroyasu Watabe

Kozo Nogi

Nobuyuki Harada

Satoshi Matsumoto

Kazuki Kimura

Hirotama Fujimaru

Yoshifumi Adachi

Yoshiro Mitsukami

Hideyuki Tahara

Toru Yanase

Hiroko Okochi

Tsuyoshi Yorino

Masafumi Inoue

Tomoyuki Arake

Hiroki Hayashi

Naoki Katakura

Yoshiki Katada

Yoshiniko Masuda

A production method includes a surface-crosslinking step of heating a mixture of a surface-crosslinking agent and a particulate dried polymer obtained with an acid group-containing unsaturated monomer as a main component. A moisture content of the particulate dried polymer is not greater than 15% by mass. A heating device including a rotary container and a plurality of heating tubes that are located within the rotary container, extend in an axial direction of the rotary container, and rotate together with the rotary container, is used in the surface-crosslinking step. The heating device includes a means for introducing and discharging a gas into and from the rotary container.

Method for producing water-absorbent resin particles

The production method includes a drying step of drying a particulate crosslinked hydrogel polymer obtained by polymerizing a monomer, which is a material of a water-absorbent resin, using a heating device to obtain dried particles. The heating device includes: a rotary container that contains the particulate crosslinked hydrogel polymer therein and rotates; and a plurality of heating tubes that are located within the rotary container, extend in an axial direction of the rotary container, and rotate together with the rotary container. A gel temperature of the particulate crosslinked hydrogel polymer to be subjected to the drying step, the gel temperature being measured by a contact thermometer, is not lower than 50&#xb0; C.

Method for producing water-absorbent resin powder, and drying device and drying method for particulate hydrous gel

The production method includes: a gel-crushing step of grinding a crosslinked hydrogel polymer to obtain a particulate crosslinked hydrogel polymer; a heating drying step of obtaining dried particles from the particulate crosslinked hydrogel polymer by using a continuous stirring drying machine; a post-crosslinking step of post-crosslinking the particulate crosslinked hydrogel polymer or the dried particles; and a sizing step of adjusting a particle size of the dried particles or the post-crosslinked dried particles to obtain water-absorbent resin powder. The particulate crosslinked hydrogel polymer contains a gel fluidizer. A gel temperature of the particulate crosslinked hydrogel polymer containing the gel fluidizer, the gel temperature being measured by a contact thermometer, is not lower than 50&#xb0; C. In the production method, the dried particles or the post-crosslinked dried particles is forcedly cooled before the sizing step.

Method for producing water-absorbent resin powder and production apparatus therefor

[Object] To provide a method for producing a water-absorbent resin in powder form or particle form, which has excellent physical properties such as water absorption performance and the like, at high productivity. [Solution] A method for producing a water-absorbent resin includes: a polymerization step of polymerizing a monomer, which is a raw material of the water-absorbent resin, to obtain a hydrous gel crosslinked polymer dispersed in an organic solvent; and a separation step of separating the organic solvent and the hydrous gel crosslinked polymer. The separation step includes transfer, compression, and discharge of the hydrous gel crosslinked polymer.

Method for producing water absorbent resin

[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&#xb0; 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.

Method for producing water-absorbent resin

An object of the present invention is to provide a water absorbing agent having a low amount of residual monomer, small variance of the amount of residual monomer among ranges of particle size distribution and favorable absorption properties, and being sanitary; an absorbing article; and a method for the production of a water absorbing agent. The water absorbing agent of the present invention has the amount of residual monomer of not higher than 500 ppm, and a residual monomer index of not greater than 0.30. The method for the production includes a first step of obtaining a hydrogel polymer by polymerizing an aqueous solution of a monomer including an unsaturated carboxylic acid and/or a salt thereof in the presence of a crosslinking agent; a second step of obtaining a water absorbent resin precursor which is in powder form and includes particles having a particle size of 300 to 850 &#x3bc;m and particles having a particle size of smaller than 300 &#x3bc;m as main components by drying said hydrogel polymer followed by pulverization and classification to adjust the particle size distribution, a third step of obtaining a water absorbent resin by heating a mixture of said water absorbent resin precursor and a surface crosslinking agent, which can form an ester bond around the surface of said water absorbent resin precursor, a fourth step of adding by spraying an aqueous solution that includes a sulfur-containing reducing agent to said water absorbent resin, and a fifth step of subjecting the mixture of the water absorbent resin and said aqueous solution to a heat treatment under an airflow of not lower than 40&#xb0; C. but not higher than 120&#xb0; C.

Particulate water absorbing agent comprising crosslinked absorbent resin and having low residual monomer, water absorbing article and method for production of water absorbing agent

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.

Method for surface crosslinking water-absorbing resin and method for manufacturing water-absorbing resin

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.

Production method for hydrophilic polymer

A hydrogel polymer obtained by polymerizing a monomer component including acrylic acid (salt) is post-neutralized so that each of polymer particles derived from a polymer produced by neutralizing the hydrogel polymer has an allowable neutralization ratio. The polymer as obtained by neutralizing the hydrogel polymer is reacted with a crosslinking agent reactive to a functional group of the polymer. The allowable neutralization ratio, for example, is a neutralization ratio which is not lower, by not less than 20 mole percent, or more than, at least 55 mole percent, than an average neutralization ratio of a mass of the polymer particles, and the post-neutralization is carried out so that a number of polymer particles having a non-allowable neutralization ratio outside the allowable neutralization range is not more than 10 in 200 polymer particles, thus obtaining a water-absorbent agent having high absorbency under no applied pressure and high pressure wherein the amount of water soluble component is lower compared with the conventional water-absorbent agent and a change in pH of a swollen gel is small.

Water-absorbent agent and method for manufacturing the same

An absorbing agent has a diffusing absorbency under pressure of not less than 25 g/g when 60 minutes elapsed after absorption is started, and a water-soluble content is above 0 percent by weight and not more than 7 percent by weight. The absorbing agent is prepared by surface-crosslinking a precursor of the absorbing agent obtained by performing an aqueous solution polymerization of a hydrophilic unsaturated monomer having not less than 50 mole percent neutralized acrylic acid as a main component using a specific crosslinking agent having a main component composed of an ester compound of a specific polyhydroxy alcohol and an unsatuated carboxylic acid, and a high-boiling component having at least two alcohol structures in a molecule as a specific ratio. As a result, an absorbing agent having excellent properties such as the diffusing absorbency under pressure is high, the water soluble content is small, and the amount of wet back of the aqueous liquid after a long period of time is small, water absorbency under pressure can be stably maintained for a long period of time can be achieved.

Process for manufacturing an absorbing agent and absorbent material

Process of manufacturing precursor of an absorbing agent

Absorbing agent, process of manufacturing same, and absorbent product

A method for the surface treatment of an absorbent resin is proposed which notably improves the absorption capacity of the absorbent resin under pressure without impairing safety and hydroscopic flowability. The method comprises adding an organic carboxylic ester of a polyhydric alcohol to the absorbent resin and then heat-treating the resultant mixture.

Method for surface treatment of absorbent resin

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Himeji, Japan

Shin-Ichi Fujino