Abstract: A method for producing a water-absorbent resin, characterized in that a precursor of the water-absorbent resin obtained by polymerizing a water-soluble ethylenically unsaturated monomer is subjected to a post-crosslinking reaction in the presence of a compound having plural hydrazide groups. The water-absorbent resin obtained by the method for producing a water-absorbent resin of the present invention is excellent in properties such as water-retention capacity, water-absorption capacity under load, and gel strength, and also gives consideration to safety of the water-absorbent resin by reducing water-soluble substance. Therefore, the water-absorbent resin of the present invention can be suitably used, for example, in hygienic materials such as disposable diaper, incontinence pad and sanitary napkin, in particular, in disposable diaper.

Abstract: The present invention provides a process for producing water-absorbing resin particles which possess a high water retention capacity (absorbing capacity), a high water-absorbing capacity under pressure, and a high gel strength and a small amount of water-soluble substance and is favorably usable in sanitary materials; water-absorbing resin particles obtained by the process; and absorbent materials and absorbent articles made by using the particles. More specifically, the water-absorbing resin particles are produced by a process for producing water-absorbing resin particles, comprising a step of a post-crosslinking reaction by adding a post-crosslinking agent in at least two stages to a water-absorbing resin particle precursor obtained by polymerization of a water-soluble ethylenic unsaturated monomer to carry out the post-crosslinking reaction.

Abstract: A method for producing a water-absorbent resin, characterized in that a precursor of the water-absorbent resin obtained by polymerizing a water-soluble ethylenically unsaturated monomer is subjected to a post-crosslinking reaction in the presence of a compound having plural hydrazide groups. The water-absorbent resin obtained by the method for producing a water-absorbent resin of the present invention is excellent in properties such as water-retention capacity, water-absorption capacity under load, and gel strength, and also gives consideration to safety of the water-absorbent resin by reducing water-soluble substance. Therefore, the water-absorbent resin of the present invention can be suitably used, for example, in hygienic materials such as disposable diaper, incontinence pad and sanitary napkin, in particular, in disposable diaper.

Abstract: The present invention provides a process for producing water-absorbing resin particles which possess a high water retention capacity (absorbing capacity), a high water-absorbing capacity under pressure, and a high gel strength and a small amount of water-soluble substance and is favorably usable in sanitary materials; water-absorbing resin particles obtained by the process; and absorbent materials and absorbent articles made by using the particles. More specifically, the water-absorbing resin particles are produced by a process for producing water-absorbing resin particles, comprising a step of a post-crosslinking reaction by adding a post-crosslinking agent in at least two stages to a water-absorbing resin particle precursor obtained by polymerization of a water-soluble ethylenic unsaturated monomer to carry out the post-crosslinking reaction.