Nippon Shokubai Co., Ltd.

Seiji Kato

Makoto Matsumoto

Kenji Kadonaga

Shinichi Fujino

Masazumi Sasabe

Satoshi Matsumoto

Motohiro Imura

Kenji Tada

Hidenori Wada

Yoshio Irie

Katsuyuki Wada

Yorimichi Dairoku

Yoshihiko Masuda

Kazumasa Konishi

Toshihiro Takaai

Takaaki Kawano

Atsushi Tachibana

Atsushi Motoyama

Shigeru Oka

Makoto Eto

Noboru Nabara

Ryuichi Otani

Yasuhiro Kawaguchi

Narimasa Okugawa

Kentaro Ichikawa

As a method for producing a polyacrylic acid (salt)-based water absorbent resin particle which less generates fine powder and has an excellent impact resistance and a high moisture content even in a case where the polyacrylic acid (salt)-based water absorbent resin particle is produced on a large scale, employed is a production method including the steps of: (a) adding a surface crosslinking agent solution to water absorbent resin powder to obtain a mixture; (b) reacting the mixture; and, thereafter (c) adding an aqueous liquid to at least one selected from the group consisting of (i) the water absorbent resin powder during the step (b) and (ii) the water absorbent resin powder after the step (b), an atmospheric dew point being not lower than 20&#xb0; C. in the step (c), and a temperature of the water absorbent resin powder being higher than the atmospheric dew point in the step (c).

Method for producing polyacrylic acid (salt)-based water absorbent resin

A method is disclosed for inexpensively and stably producing, with high productivity, water absorbent resin having excellent damage resistance. A method for producing a polyacrylic acid (salt)-based water absorbent resin, the method comprising a surface-crosslinking step, the surface-crosslinking step including a reaction step, the reaction step involving using a reactor having (i) an inner wall surface having a temperature within a range of 100&#xb0; C. to 250&#xb0; C. and (ii) an inside atmosphere having a dew point within a range of 60&#xb0; C. to 100&#xb0; C., the reaction step including heat-treating a water absorbent resin mixture so as to produce water absorbent resin powder having a temperature within a range of 90&#xb0; C. to 130&#xb0; C.

Method for producing polyacrylic acid (salt)-based water-absorbent resin

The present invention is a method for producing a water absorbent resin which method is a method for producing surface cross-linked water absorbent resin particles, the method including the successive steps of: (a) adding a surface cross-linking agent and water to a particulate water absorbent resin in a mixer; and (b) reacting the resulting water absorbent resin mixture taken out from the mixer with the surface cross-linking agent in a reactor by heating or active energy ray irradiation, water vapor being used as part or all of the water added in the mixer. This makes it possible to provide a method for producing a water absorbent resin in which method a surface cross-linked water absorbent resin that has excellent properties can be obtained efficiently at low cost with high productivity.

Method for producing water absorbent resin

Provided is a method for producing a polyacrylic acid (salt)-based water absorbent resin in which the physical properties (especially liquid permeability) are improved and maintained even in large scale production. The method for producing a polyacrylic acid (salt)-based water absorbent resin, which sequentially includes a polymerization step, in which a monomer aqueous solution having acrylic acid (salt) as a main component is polymerized, a drying step, in which a water-containing gel-like crosslinked polymer obtained in the polymerization step is dried, and a classification step, in which a polymer obtained in the drying step is classified, wherein a rocking-type sieve classification apparatus is used in the classification step, and the rocking-type sieve classification apparatus has a sieve net having a trajectory and a rotation speed in the following ranges; radial gradient R: from 5 to 40 mm, tangential gradient T: from 0.1 to 25 mm, eccentric gradient E: from 40 to 80 mm, and rotation speed F: from 60 to 600 rpm.

Process for producing polyacrylic acid (salt)-based water absorbent resin

An object of the present invention is to provide a simple method for improving and stabilizing the physical properties (for example, liquid permeability) of a water absorbent resin, without requiring investment in expensive facilities or modification of raw materials. In particular, the object is to provide a method which is useful in the large-scale production of a water absorbent resin. The method for producing polyacrylic acid (salt)-based water absorbent resin of the present invention includes, in order, a step in which an acrylic acid (salt)-based monomer aqueous solution is polymerized, a step in which the water-containing gel-like crosslinked polymer obtained in the polymerization step is dried, a step in which the dried polymer obtained in the drying step is pulverized, and a classification step which takes place after the drying step or after the pulverizing step, wherein, at the time of providing the dried polymer to the roll mill used in the pulverizing step, the dried polymer is provided in a dispersed state in the axial direction of the roll of the roll mill.

An object of the present invention is to provide a waste solution solidifying agent which can solidify a waste solution, particularly, a waste solution containing blood or body fluid at a low cost, uniformly, and in a short time; in particular, to provide a waste solution solidifying agent which can solidify a waste solution uniformly and in a short time in a vertically oriented waste solution equipment. As a means of achieving this object, a waste solution solidifying agent of the present invention is a particulate treating agent used in a method of treating a waste solution which solidifies a waste solution into a gel by placing a treating agent in a waste solution, and is characterized in that said agent contains, as an essential component, a water-absorbent resin having a crosslinked structure obtained by polymerizing a water-soluble ethylenic unsaturated monomer and, when flowing-placed at once into a 0.90 mass % aqueous sodium chloride solution, 20 to 95 mass % of the agent is floated, and 80 to 5 mass % is settled. And a process for preparing a waste solution solidifying agent of the present invention is a process for preparing a particulate waste solution solidifying agent containing, as an essential component, a water-absorbent resin having a crosslinked structure obtained by polymerizing a water-soluble ethylenic unsaturated monomer, and comprises a step of mixing a hydrophobic substance having a methanol index of 20 or more after polymerization.

Waste solution solidifying agent, process for preparing the same and use of the same

The present invention provides a surface treatment method for a water-absorbing resin comprising three steps of:

Surface treatment method for water-absorbing resin and production method for water-absorbing resin

A water absorbent resin is dried in a continuous fluidized bed having a heat transfer tube and at least two drying rooms. Pulverization is performed between a first drying room at not less than 80&#xb0; C. to not more than 200&#xb0; C. and a second or subsequent room at not less than 100&#xb0; C. to not more than 220&#xb0; C. A method for producing a water absorbent resin includes: (1) polymerizing a monomer aqueous solution; (2) drying a hydrogel polymer of step (1); (3) performing particle size control of the dry polymer of the step (2); (5) surface crosslinking the water absorbent resin powder of step (3), and step (4) of performing a second heat drying on the water absorbent resin powder of step (3), preceding step (5). The water absorbent resin has a moisture content of 0 wt % to 3 wt % before the step (5).

Process for producing water-absorbing resin

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Himeji, Japan

Seiji Kato