Sumitomo Seika Chemicals Co., Ltd.

Atsushi Heguri

Nobuhiro Maeda

Hideki Yokoyama

Sachi Kikuno

Masayoshi Handa

Yuichi Onoda

Kenji Tanimura

There is disclosed a method for producing water-absorbent resin particles, comprising a polymerization step that includes mixing an oily liquid comprising a hydrocarbon dispersing medium and a surfactant, and an aqueous liquid comprising an aqueous solvent and a water-soluble ethylenically unsaturated monomer, forming a suspension comprising an oily liquid and an aqueous liquid dispersed in the oily liquid, and polymerizing the water-soluble ethylenically unsaturated monomer in the suspension. The HLB of the surfactant is 6 or greater, and the temperature of the suspension is kept at 35&#xb0; C. or higher during the period from initial mixing of the oily liquid and aqueous liquid until complete mixing of the entire amounts.

Method for producing water absorbent resin particles

The present invention provides a method for producing water-absorbing resin particles having high equilibrium swelling capacity, a high water-absorption rate or high initial swelling capacity, and an appropriate particle size that achieves good handling performance; water-absorbing resin particles obtained by the method; and a water blocking material and an absorbent article which include the water-absorbing resin particles. The present invention is a method for producing water-absorbing resin particles, which comprises: preparing a hydrogel polymer by reversed-phase suspension polymerization of a water-soluble ethylenically unsaturated monomer in a hydrocarbon solvent in the absence of an internal crosslinking agent but in the presence of a surfactant with an HLB of 8 to 12; carrying out a post-crosslinking reaction of the hydrogel polymer whose moisture content is adjusted to 30 to 110 mass % based on a water-soluble ethylenically unsaturated monomer component that composes the hydrogel polymer.

Process for production of water-absorbing resin particles, water-absorbing resin particles, water-stopping material, and absorbent article

Disclosed is a water-absorbent resin particle in which the water-absorption rate of physiological saline is 1 second to 15 seconds, the median particle size is 100 &#x3bc;m to 600 &#x3bc;m, and the residual volatile component content is 1.5% by weight or less.

Water absorbing resin particles, method for manufacturing water absorbing resin particles, absorption body, absorptive article, and water-sealing material

A method for producing a water-absorbent resin comprising at least two stages of reversed-phase suspension polymerization, wherein the first stage of the at least two stages of reversed-phase suspension polymerization comprises the following steps of: (A) performing a primary dispersion by stirring to mix in the absence of surfactants an aqueous solution of a water-soluble ethylenically unsaturated monomer containing a hydrophilic polymeric dispersion agent with a petroleum hydrocarbon dispersion medium in which a hydrophobic polymeric dispersion agent dissolves or disperses; (B) further performing a secondary dispersion by adding a surfactant to the resultant dispersion liquid; and (C) performing a polymerization by using a water-soluble radical polymerization initiator to obtain a water-absorbent resin as particles in a hydrous gel state which disperse in the petroleum hydrocarbon dispersion medium, and a water-absorbent resin obtained by the method.

Method for producing a water-absorbent resin

A method is disclosed for producing a water-absorbent resin by a reversed-phase suspension polymerization method, wherein an odor originating from a raw material component, in particular, a petroleum hydrocarbon dispersion medium, is further reduced as compared with a water-absorbent resin obtained by a conventional method, and a water-absorbent resin obtained by the method. More specifically, a method is disclosed for producing a water-absorbent resin by performing a reversed-phase suspension polymerization of a water-soluble ethylenically unsaturated monomer in a petroleum hydrocarbon dispersion medium, comprising adding and dispersing an aqueous solution of a water-soluble ethylenically unsaturated monomer containing a hydrophilic polymeric dispersion agent to a petroleum hydrocarbon dispersion medium in the presence of a surfactant under stirring, and performing a reversed-phase suspension polymerization using a radical polymerization initiator, and a water-absorbent resin obtained by the method.

The present invention provides a method for producing water-absorbent resin particles which show an excellent water absorption rate and high equilibrium swelling capacity and which have an appropriate particle size to be excellent in handleability, and water-absorbent resin particles obtained by the method. The present invention is a method for producing water-absorbent resin particles by reversed phase suspension polymerization of a water-soluble ethylenically unsaturated monomer, the method including the steps of: (A) first reversed phase suspension polymerization of a water-soluble ethylenically unsaturated monomer in a petroleum hydrocarbon dispersion medium using a water-soluble radical polymerization initiator, in the absence of an internal crosslinking agent and in the presence of a surfactant having an HLB of 8 to 12; (B) intermediate crosslinking reaction by adding an intermediate crosslinking agent; (C) second reversed phase suspension polymerization of a water-soluble ethylenically unsaturated monomer added to the petroleum hydrocarbon dispersion medium containing the surfactant dissolved therein using a water-soluble radical polymerization initiator in the absence of an internal crosslinking agent, thereby producing a water-absorbent resin precursor; and (D) post crosslinking reaction of the water-absorbent resin precursor preliminary adjusted to have a moisture content of 30 to 100% by mass relative to a water-soluble ethylenically unsaturated monomer component in the water-absorbent resin precursor.

Method for producing water-absorbent resin particles and water-absorbent resin particles

A method for producing a water-absorbent resin by performing a reversed-phase suspension polymerization of a water-soluble ethylenically unsaturated monomer in a petroleum hydrocarbon dispersion medium, comprising the following steps of: (A) performing a primary dispersion in the absence of surfactants by adding an aqueous solution of a water-soluble ethylenically unsaturated monomer containing a hydrophilic polymeric dispersion agent to a petroleum hydrocarbon dispersion medium in which a hydrophobic polymeric dispersion agent was heat-dispersed or heat-dissolved, under stirring; (B) further performing a secondary dispersion by adding a surfactant to a dispersion liquid obtained after the primary dispersion; and (C) performing the reversed-phase suspension polymerization by using a radical polymerization initiator; and the water-absorbent resin obtained by the method.

A method for producing a water-absorbent resin having a further reduced odor as compared with a water-absorbent resin obtained by a conventional method as well as a water-absorbent resin produced by the same method, by maintaining the addition rate V from the pouring nozzle for the aqueous solution of the water-soluble ethylenically unsaturated monomer in a polymerization reaction tank not more than 0.30 [min], in the first stage polymerization step which is within the step of the conventional method upon performing multi-stages such as two or more stages of reversed-phase suspension polymerizations in a method for producing a water-absorbent resin, and thereby by being able to reduce the amount of the petroleum hydrocarbon dispersion medium remaining in the above water-absorbent resin.

The present invention provides a method for producing a water-absorbent resin by a reversed-phase suspension polymerization method, wherein an odor originating from a raw material component, in particular, a petroleum hydrocarbon dispersion medium, was reduced, and a water-absorbent resin obtained by the method. More specifically, the present invention provides a method for producing a water-absorbent resin comprising performing a reversed-phase suspension polymerization of a water-soluble ethylenically unsaturated monomer in a petroleum hydrocarbon dispersion medium by using a surfactant, wherein an aqueous solution of the water-soluble ethylenically unsaturated monomer is dispersed in the dispersion medium at a specific pouring rate to reduce an odor, and a water-absorbent resin obtained by the method, are provided.

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Himeji, Japan

Atsushi Heguri