Nippon Shokubai Co., Ltd.

Kazuhisa Hitomi

Kunihiko Ishizaki

Nobuyuki Harada

Yorimichi Dairoku

Takumi Hatsuda

Shigeru Sakamoto

Katsuhiro Kajikawa

Soichi Yamada

Toshimasa Kitayama

Kazushi Torii

Katsuyuki Wada

Hiroyuki Ikeuchi

Shinichi Fujino

Tadao Shimomura

Yasuhiro Fujita

Yoshifumi Adachi

Yasuhisa Nakashima

Makoto Nagasawa

Teruyuki Kanto

Koichi Yonemura

Akiko Mitsuhashi

Takaya Hayashi

Shigenori Kirimura

Yuji Yamamoto

There is provided: a production process for a water-absorbing agent having stable properties in a short time; and a water-absorbing agent. The production process comprises the step of blending an acid-group-containing water-absorbent resin powder with a noncrosslinkable water-soluble inorganic base and/or an irreducible alkaline-metal-salt pH buffer and further with a dehydratable crosslinking agent reactable with the acid group, thereby subjecting the resin powder to crosslinking treatment, or comprises the step of blending an acid-group-containing water-absorbent resin powder with the above base and/or pH buffer and further with a crosslinking agent reactable with the acid group, thereby subjecting the resin powder to crosslinking treatment, wherein the resin powder has a weight-average particle diameter of 300 to 600 &#x3bc;m wherein the ratio of fine powders having particle diameters of not larger than 150 &#x3bc;m in the resin powder is not more than 10 weight %.

Water-absorbing agent and production process therefor, and sanitary material

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

The present invention provides: a production process for a basic water-absorbent resin to be a main component of a water-absorbing agent which exhibits an excellent water absorption capacity under a load with high productivity; a production process for a water-absorbing agent; and use thereof. The production process for an irregular shape basic water-absorbent resin comprises the step of reacting a basic resin and a crosslinking agent in order to obtain the basic water-absorbent resin, with the process forwarding a crosslinking reaction and pulverizing the resultant product at the same time. The first production process for a water-absorbing agent comprises the step of blending an acidic water-absorbent resin with the basic water-absorbent resin obtained by the above-mentioned process. The second production process for a water-absorbing agent comprises the step of obtaining a mixture of an acidic water-absorbent resin and the basic water-absorbent resin by coexisting with the acidic water-absorbent resin when carrying out the crosslinking reaction and the pulverization in the above-mentioned process.

Production processes for basic water-absorbent resin and water-absorbing agent, and use thereof

The present invention has an object to provide a process for producing a water-absorbing agent which is excellent in the absorption capacities under no load and under a load with good balance and can display excellent absorption properties even if the weight percentage of a water-absorbent resin (resin concentration) is high when the water-absorbent resin is used for materials such as sanitary materials. The above object can be achieved by adding a vinyl compound or both the vinyl compound and a polyhydric alcohol to a water-absorbent resin and heating the resultant mixture.

Water-absorbing composition and production process for water-absorbing agent

The present invention provides a surface-crosslinking process of a water-absorbent resin to obtain a water-absorbing agent which has high absorption speed and excellent absorption capacity under a load (a water-absorbent resin which has specific or larger values of properties). In a process comprising the step of adding a crosslinking agent to a dry water-absorbent resin powder to thereby crosslink the neighborhood of its surface, the surface-crosslinking is carried out while the resin powder having a weight-average particle diameter of 200 to 1,000 &mgr;m is pulverized.

Surface-crosslinking process for water-absorbent resin

Water-absorbent resins which are prepared by mixing polysaccharides with amino acids (amino acids and/or polymers of amino acids) and heating the mixture so as to cause a crosslinking reaction therein. Each of the water-absorbent resins has a water-absorbing ratio of not less than 10 g/g with respect to physiologic saline as well as having a rate of biodegradability of not less than 10%. Moreover, its water-absorbing ratio under pressure is not less than 10 ml/g with respect to physiologic saline. The water-absorbing ratio under pressure is measured by using a measuring device that is constituted of a weighing machine, a container, an air-intake pipe, a conduit, a glass filter, and a measuring section. The water-absorbent resins are superior in both water-absorbing capacity and biodegradability, and are capable of maintain their water-absorbing capacity even under pressure.

Water-absorbent resins and manufacturing methods thereof

A process for producing a water-absorbing resin, which comprises polymerizing (D) an aqueous solution comprising (A) at least one monomer component selected from the group consisting of an unsaturated carboxylic acid and salts thereof; (B) a compound having two or more unsaturated groups in a molecule; and (C) a compound having two or more functional groups which are capable of reacting with carboxyl groups in a molecule, the polymerization being conducted in such a manner that the following conditions (a) to (c) are simultaneously satisfied: (a) the molar ratio (B)/(C) being in the range of from 2.times.10.sup.-3 to 300, (b) the polymerization being initiated by a redox polymerization initiator, and (c) the maximum reaction temperature being in the range of from 60.degree. to 100.degree. C, and a water-absorbing resin having a degree of reduction in absorption magnification of from 1 to 16, and n absorption magnification under pressure of from 20 to 40.

Water-absorbing resin and process for producing same

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Himeji, Japan

Kazuhisa Hitomi