Sumitomo Seika Chemicals Co., Ltd.

Shinya Fukudome

Junichi Takatori

Jun Sakata

Masayoshi Handa

Yasuhiro Nawata

Tetsuhiro Hinayama

Nobuhiro Maeda

Koji Ueda

Kiyoshi Yamaguchi

Noriko Honda

Kenya Matsuda

Junichi Maruo

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

A water-absorbent sheet composition containing a structure in which an absorbent layer containing a water-absorbent resin and an adhesive is sandwiched with two or more sheets of hydrophilic nonwoven fabrics, wherein the water-absorbent sheet composition has a structure in which the absorbent layer is separated in divided parts of a primary absorbent layer and a secondary absorbent layer with a water-permeable substrate having a water permeability index of from 20 to 90, and wherein the water-absorbent resin is contained in the absorbent layer in an amount of from 100 to 1000 g/m. The water-absorbent sheet composition of the present invention exhibits some excellent effects that the water-absorbent sheet composition is capable of accomplishing thinning and avoidance of gel blocking phenomenon and liquid leakage, while obtaining basic properties as a water-absorbent sheet composition at a high level, even for a water-absorbent sheet composition containing a very small amount of pulps.

Water-absorbent sheet composition

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.

Process for production of water-absorbing resin

Growing community of inventors

Himeji, Japan

Shinya Fukudome