Nippon Shokubai Co., Ltd.

Syuji Kanzaki

Kunihiko Ishizaki

Kozo Nogi

Satoshi Matsumoto

Sumio Okuda

Shinichi Fujino

Yorimichi Dairoku

Yoshiro Mitsukami

Koji Matsumoto

Kazumasa Konishi

The disclosed process for continuously producing a water-absorbing resin comprising a plurality of joined continuous steps; a polymerization step of polymerizing an aqueous unsaturated monomer solution, a drying step of drying a particulated water-containing gel-like crosslinked polymer obtained in a finely crushing step during the polymerization or after the polymerization, a pulverizing step after the drying, a classification step after the drying, and a surface treatment step for the water-absorbing resin powder after the classification step. In the process, with some of the above steps kept running, the other steps are interrupted, and subsequently all the steps are restarted.

Process for producing water-absorbing resin

A method for producing a water absorbent resin, the method including a polymerization step, a drying step, a classification step, and a surface crosslinking step. The classification step carried out before or after the surface crosslinking step requires use of a tapping material and a metal sieve mesh, in which the tapping material being heated at 40&#xb0; C. to 100&#xb0; C. is installed below the metal sieve mesh, and the metal sieve mesh has an area of 1 to 10 m/sheet. The classification step further requires introducing a classification aid particle, which has a specific gravity different from that of the water absorbent resin, to the metal sieve mesh; and monitoring the presence or absence of damage to the metal sieve mesh.

Method of producing water absorbent resin

The purpose of the present invention is to provide a method for producing a water absorbent resin in which a water absorbent resin having excellent properties can be obtained effectively. The present invention relates to a method for producing a polyacrylic acid (salt)-based water absorbent resin, which includes a polymerization step of polymerizing an aqueous monomer solution containing a polymerization inhibitor, acrylic acid (salt) and an internal cross-linking agent to produce a water-containing gel-like cross-linked polymer, a gel-crushing step of performing the gel-crushing of the water-containing gel-like cross-linked polymer simultaneously with or subsequent to the polymerization to produce a particulate water-containing gel-like cross-linked polymer, and a drying step of supplying the particulate water-containing gel-like cross-linked polymer to a continuous through-flow belt-type dryer by a traverse conveyor to dry the particulate water-containing gel-like cross-linked polymer, in which the belt temperature of the traverse conveyor is 40 to 120&#xb0; C. and/or the water soluble component in the particulate water-containing gel-like cross-linked polymer on the traverse conveyor is 10% by weight or less and the water soluble component is increased after the drying step.

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

A method for producing a water absorbent resin, the method including a polymerization step, a drying step, a classification step, and a surface crosslinking step. The classification step carried out before or after the surface crosslinking step requires use of a metal sieve mesh having stretch tension from 35 to 100 N/cm, in which an air jet cleaner or an air jet brush cleaner and plural tapping balls or tapping blocks are installed below the metal sieve mesh, a classification aid particle having specific gravity different from that of the water absorbent resin powder is added, and a fine powder of the water absorbent resin and the classification aid particle are removed.

The disclosed process for producing a water-absorbing resin comprising: a polymerization step of polymerizing an aqueous unsaturated monomer; and a drying step of drying a particulated water-containing gel-liked crosslinked polymer, obtained in a finely crushing step during the polymerization or after the polymerization. In the process, the drying step is interrupted with a dryer kept in a heated state and thereafter the drying step is restarted.

The disclosed process for producing a water-absorbing resin comprising: a polymerization step of polymerizing an aqueous unsaturated monomer; a drying step of drying a particulated water-containing gel-liked crosslinked polymer, obtained in a finely crushing step during the polymerization or after the polymerization; a pulverizing step after the drying, a classification step after the drying, and a surface treatment step after the classification. In the process is, the surface-treatment step is interrupted with a heating treatment apparatus kept in a heated state and thereafter the surface treatment step is restarted.

Disclosed is a method for producing a water absorbent resin, by which a surface-crosslinked water absorbent resin having excellent physical properties can be efficiently obtained at low cost, while assuring high productivity. When the production scale is increased to a continuous production on a huge scale (for example, 1 t/hr or more), the physical properties are improved and stabilized (for example, standard deviation of the physical properties is reduced) by a surface-crosslinking treatment, and the absorption against pressure (AAP) and liquid permeability (SFC) are further improved. Specifically disclosed is a method for producing a polyacrylic acid (salt)-type water absorbent resin, which comprises: a step of preparing an aqueous monomer solution using an acrylic acid (salt); a step of continuously polymerizing the aqueous monomer solution; shedding step of a hydrous gel-like crosslinked polymer during or after the polymerization; a step of drying the thus-obtained particulate hydrous gel-like crosslinked polymer; and a surface treatment step in which a surface-crosslinking agent is added to and reacted with the dried water absorbent resin powder. In the surface treatment step, the continuous mixing apparatus for the surface treatment agent and the continuous heating device are connected and periodic shielding is performed between the mixing apparatus and the heating device.

Polyacrylic acid (salt)-type water absorbent resin and method for producing of same

A method for reducing colored foreign substances in a water absorbent resin by a convenient and simple technique in the production of a water absorbent resin, without requiring any modification of raw materials or high capital investment, is provided. The method for producing a particulate water absorbent resin includes a step of polymerizing an aqueous solution of an unsaturated monomer; and a step of drying a particulate water-containing gel-like cross-linked polymer having a solids concentration of 30% by weight or greater that is obtainable in a gel grain refining step during polymerization or after polymerization, with one or more apparatuses for aerating a water absorbent resin with a high temperature gas stream being installed in the drying step and/or in at least one of the subsequent steps, while in the aerating apparatus, the high temperature gas stream is passed through a filter and then is reused in the same step as the step where the aerating apparatus is installed, or in a different step.

Method for producing particulate water absorbent resin

A method for the production of a water-absorbing resin is to be provided which permits enhancement and stabilization of property, for example, liquid permeability, of a water-absorbing resin by a simple and convenient method without requiring change of raw materials or expensive facility investment. The method comprises a polymerization step for polymerizing an aqueous solution of acrylic acid (or salt thereof) to obtain a hydrogel cross-linked polymer; a drying step for drying the hydrogel cross-linked polymer to obtain a water-absorbing resin powder; a classification step for classifying the water-absorbing resin powder; and a surface cross-linking step for surface cross-linking the water-absorbing resin powder before or after the classification step, wherein electricity is eliminated in the classification step.

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Hyogo, Japan

Syuji Kanzaki