Sumitomo Seika Chemicals Co., Ltd.

Junichi Takatori

Shinya Fukudome

Jun Sakata

Masayoshi Handa

Tetsuhiro Hinayama

Kimihiko Kondo

Yasuhiro Nawata

Nobuhiro Maeda

Masahiro Murakami

Ayaka Watanabe

Hideki Matsushita

Haruka Inaba

Noriko Honda

Kenya Matsuda

Naoaki Hara

Kana Kudo

Junichi Maruo

One purpose of the present invention is to provide a water-absorbent resin having excellent water absorption characteristics and being capable of improving the shape-retaining characteristics of a water-absorbent material when used in the water-absorbent material. A water-absorbent resin obtained by performing reversed phase suspension polymerization of a water-soluble ethylenically unsaturated monomer in a hydrocarbon dispersion medium, using a radical polymerization initiator, said resin being capable of having both excellent absorption performance and shape retention in a water-absorbent material using the water-absorbent resin, as a result of fulfilling the conditions of: (1) having a water-retention capacity of physiological saline of at least 38 g/g; (2) having a water-absorption capacity of physiological saline under a load of 4.14 kPa of at least 15 ml/g; and (3) having a tan &#x3b4; of a 50-fold swollen gel of at least 2.10&#xd7;10.

Water-absorbent resin, water-absorbent material, and water-absorbent article

A polymerization reactor of the present invention includes a container bodyand a jacketcovering the outer surface of the container bodyand defining a passage for passing a cooling/heating medium between itself and the outer surface of the container body. The container bodyis made of a clad metal plate including a support metal layerhaving an inner surface at an inner side of the container body and an outer surface at an outer side of the container body, and an inner corrosion-resistant metal skin layerbonded to the inner surface of the support metal layer and being smaller in thickness than the support metal layer.

Polymerization reactor and method for producing water absorbent resin

The present invention provides a process for producing a water-absorbent resin, characterized in that a reverse-phase suspension polymerization of a water-soluble ethylenically unsaturated monomer is carried out in a hydrocarbon dispersion medium comprising a dispersion stabilizer while an azo-based compound and a peroxide are combined in the presence of an internal-crosslinking agent, in that the following formulae are satisfied,0.10&#x2264;/()&#x2003;&#x2003;(1), and0.055&#x2264;+9&#xd7;&#x2264;0.120&#x2003;&#x2003;(2),

Process for producing water-absorbent resin

The present invention may provide a process for producing a water-absorbent resin by employing a reversed suspension polymerization method, by which a water-absorbent resin having a small particle size and a narrow particle size distribution can be produced. The process for producing a water-absorbent resin may include subjecting a water-soluble ethylenically unsaturated monomer to a reversed phase suspension polymerization in a petroleum hydrocarbon dispersion medium containing a surfactant and a polymeric dispersion agent, wherein the polymeric dispersion agent is a polymeric protective colloid having a weight average molecular weight (Mw) of 2,000 to 15,000 and a molecular weight distribution (Mw/number average molecular weight (Mn)) of 3 to 50.

Method for producing water-absorbent resin

A water-absorbent sheet structure comprising a structure in which an absorbent layer containing a water-absorbent resin is sandwiched with a hydrophilic nonwoven fabric from an upper side and a lower side of the absorbent layer, characterized in that at least one side of the upper side and the lower side of the water-absorbent sheet structure is subjected to embossing, wherein a central region Wof a water-absorbent sheet structurealong a longitudinal direction of the structureis subjected to: wavy embossingcomprising one wavy embossing extending along the longitudinal direction, wherein the embossing comprises one or more discontinued segments of the embossing, and linear embossingin a direction from each of tipsof wavy forms formed by the wavy embossingtowards an edge portion contouring along the longitudinal direction of the water-absorbent sheet structure, and wherein a branched structure of embossing formed by the wavy embossingand the linear embossinghas an approximate Y-shape-form, and wherein the edge portion contouring along the longitudinal direction of the water-absorbent sheet structurecomprises non-embossing regions W, W' not subjected to embossing, extending along the longitudinal direction, and further wherein an area of the embossing provided on the water-absorbent sheet structureis from 2 to 25% of an entire area of the water-absorbent sheet structure; and an absorbent article comprising the water-absorbent sheet structure, sandwiched between a liquid-permeable sheet and a liquid-impermeable sheet. According to the present invention, some effects are exhibited that a water-absorbent sheet structure which has a fast permeation rate of a liquid and is less likely to cause liquid leakage can be provided by subjecting at least an upper side or a lower side of the water-absorbent sheet structure to a specified emboss shape even when the water-absorbent sheet structure contains very little amount of pulps.

Water-absorbent sheet structure

A method for producing a water-absorbent resin including the step of subjecting a water-soluble ethylenically unsaturated monomer to a reversed phase suspension polymerization in a petroleum hydrocarbon dispersion medium in the presence of a radical polymerization initiator and a dispersion stabilizer, wherein the method is characterized by the use of an ether-ester type nonionic surfactant as the dispersion stabilizer, and a water-absorbent resin obtained by the method, wherein the water-absorbent resin has a water-retention capacity of saline solution of 25 g/g or more, a water-absorption rate of saline solution of 50 seconds or less, and a flow index under moisture absorption of 70% or more. According to the method of the present invention, a water-absorbent resin having high water-retention capacity, excellent water-absorption rate, and further having excellent flowability under moisture absorption can be produced. The water-absorbent resin having the specified physical properties as described above can enhance properties of hygienic materials, and the resin can be suitably used in the production of the hygienic materials.

Method for producing water-absorbent resin, and water-absorbent resin obtained by same

The invention provides a novel method for producing a water-absorbent resin comprising: subjecting at least one water-soluble ethylenic unsaturated monomer to reversed-phase suspension polymerization in a petroleum hydrocarbon dispersion medium, the reversed-phase suspension polymerization being conducted using a 0.00005 to 0.00016 mole of water-soluble azo initiator for radical polymerization per mole of the water-soluble ethylenic unsaturated monomer in the presence of 0.000015 to 0.00015 mole of hypophosphorous compound per mole of the water-soluble ethylenic unsaturated monomer. According to the method, the environmental impact can be lessened by reducing the amount of petroleum hydrocarbon dispersion medium released to the outside of the system, and the method makes it possible to obtain a water-absorbent resin having a high water-retention capacity and water-absorption capacity under a load, and a small content of water soluble component at the same time.

Method for producing water-absorbing resin

Absorbent strip for incorporation into diaper or sanitary napkin

Process for preparing a water-absorbent resin comprising carrying out a reversed-phase suspension polymerization in multi-steps of two or more steps. The water-absorbent resin is prepared by subjecting a water-soluble ethylenically unsaturated monomer to the reversed phase suspension polymerization. This process for preparing a water-absorbent resin involves adding an aminocarboxylic acid compound to at least one step in the second and subsequent steps to carry out the polymerization reaction. The resulting water-absorbent resin can be suitably used in a hygienic material. The water-absorbent resin has a high degree of water-retention, including a high degree of water absorption under pressure. It also has a high water absorption rate, and contains only a small amount of water-soluble substances.

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Himeji, Japan

Junichi Takatori