Nippon Shokubai Co., Ltd.

Nippon Shokubai Kagaku Kogyo Co., Ltd.

Katsuhiro Kajikawa

Kunihiko Ishizaki

Takumi Hatsuda

Yoshio Irie

Kinya Nagasuna

Teruaki Fujiwara

Yorimichi Dairoku

Kazuhisa Hitomi

Hitoshi Takahashi

Soichi Yamada

Koji Miyake

Tadao Shimomura

Hirotama Fujimaru

Masatoshi Nakamura

Yoshihiko Masuda

Sumio Okuda

Kazumasa Konishi

Toru Nishioka

Jyunichi Saga

Hideyuki Tahara

Akito Yano

Kazutaka Yano

Takanori Murakami

Takashi Nishigaki

Sachio Fujita

A method according to the present invention for producing water absorbent resin powder is a method for producing water absorbent resin having a surface cross-linked structure, and includes: a polymerization step in which an unsaturated monomer aqueous solution is polymerized; a drying step in which a hydrogel cross-linked polymer obtained in the polymerization step is dried; a surface treatment step in which the hydrogel cross-linked polymer or a dried hydrogel cross-linked polymer is subjected to a surface treatment; and a sorting step, carried out after the drying step, in which a foreign matter included in a water absorbent resin is color-sorted from the water absorbent resin entirely or partially. As a result, it is possible to obtain a water absorbent resin which has high properties and is less likely to be colored. In this way, there is provided the water absorbent resin powder production method in which the color sorting technique is used to remove foreign matters from the water absorbent resin.

Package of water absorbent resin powder

Production method of water absorbent resin powder and package of water absorbent resin powder

There is disclosed a process for continuous production of a water-absorbent resin product by which the water-absorbent resin product having high properties can continuously be produced easily and inexpensively with stable constant quality. In addition, there is disclosed a water-absorbent resin product having high properties and being stable in quality. The process comprises the following steps of: (A) measuring a water-absorbent resin by its predetermined property and/or its predetermined component content, wherein the water-absorbent resin comes being continuously produced via a classification step and/or a surface-modifying step; (B) separating a predetermined amount of water-absorbent resin (a) from the water-absorbent resin that comes being continuously produced, wherein the water-absorbent resin (a) is a water-absorbent resin which displays not less than a definite value and/or a water-absorbent resin which displays not more than a definite value as to the predetermined property and/or the predetermined component content in accordance with results of the aforementioned measurement; and (C) mixing at least a portion of the aforementioned separated predetermined amount of water-absorbent resin (a) into a water-absorbent resin that comes being continuously produced via a classification step and/or a surface-modifying step on the same or another production line.

Process for continuous production of water-absorbent resin product

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.

Water-absorbent resin granule-containing composition and production process for water-absorbent resin granule

In the production of an acrylate polymer by the steps of preparing a water-soluble unsaturated monomer having a ratio of neutralization in the range of 30 to 100 mol % and containing 50 to 100 mol % of an acrylate and then polymerizing the monomer, a method for the production of a hydrophilic resin which comprises using a water-soluble unsaturated monomer having a &#x3b2;-hydroxy propionic acid (salt) content of not more than 1,000 ppm. The hydrophilic resin obtained by this method exhibits excellent physical properties and has only a small residual monomer content. Further, a residual monomer content neither occurs nor increases in any using conditions.

Method for production of hydrophilic resin

A surface-modified water-absorbent resin powder is produced continuously with high productivity in a state where the particle diameter distribution is narrow and where the properties are high by a process comprising a polymerizing step, a drying step, a pulverizing step, a classifying step, and a surface-modifying step, and further, conveying steps of connecting them, wherein the conveying steps include at least two hoppers for storing the water-absorbent resin powder. A powder surface detector used favorably for this process includes a float hung down by a hanging line.

Continuous production process for water-absorbent resin powder and powder surface detector used therefor

The present invention provides: a water-absorbent resin powder, which includes no fine metallic foreign substance, and in which the deterioration is suppressed; its production process; and uses. The present invention production process for a water-absorbent resin powder comprises the steps of: polymerizing an unsaturated monomer; and drying the resultant crosslinked hydrogel polymer, wherein the water-absorbent resin powder has a crosslinked structure and a mass-average particle diameter of 300 to 600 &mgr;m wherein the ratio of fine particles having particle diameters of not larger than 150 &mgr;m is less than 10 mass % of the water-absorbent resin powder, with the production process being characterized by further comprising a magnetic-flux irradiation step of passing a magnetic field having a magnetic flux density of not less than 0.05 Wb/m through the water-absorbent resin powder after the drying step in the production process.

Water-absorbent resin powder and its production process and uses

Continuous manufacturing method of water-absorbent polymer

In the production of an acrylate polymer by the steps of preparing a water-soluble unsaturated monomer having a ratio of neutralization in the range of 30 to 100 mol % and containing 50 to 100 mol % of an acrylate and then polymerizing the monomer, a method for the production of a hydrophilic resin which comprises using a water-soluble unsaturated monomer having a &bgr;-hydroxy propionic acid (salt) content of not more than 1,000 ppm. The hydrophilic resin obtained by this method exhibits excellent physical properties and has only a small residual monomer content. Further, a residual monomer content neither occurs nor increases in any using conditions.

A method for the continuous production of a shaped hydrogel of absorbent resin is disclosed. This invention accomplishes the continuous production by continuously supplying in the form of a layer a monomer mixture capable of forming an absorbent resin by polymerization and polymerizing the layer of the monomer mixture. This method is characterized by retaining the rate of change of the thickness in the direction of width of the layer of hydrogel of absorbent resin at the time of formation of gel at a level of not more than 20%. The method is advantageously carried out by the use of an apparatus for the production of a shaped hydrogel of absorbent resin which comprises a movable endless revolving support belt, a monomer mixture supplying device, and a device for discharging the shaped hydrogel of absorbent resin, the apparatus preferably being provided near each of the opposite lateral parts of the movable endless revolving support belt with a lateral weir adapted to move in concert with the belt or being provided near each of the opposite lateral parts of the movable endless revolving support belt with a lateral weir fixed in such a manner as to contact the belt in a sliding state. The method of this invention permits production of a shaped hydrogel of absorbent resin intended to afford an absorbent resin which exhibits high absorption capacity, little water-soluble content and little residual monomer only in small amounts, and enjoys a high productivity rate.

Method for production of shaped hydrogel of absorbent resin

Absorbent resin composition and method for production thereof

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Himeji, Japan

Katsuhiro Kajikawa