Abstract: Provided are a manufacturing method of water absorbing resin particle agglomerates capable of producing water absorbing resin particles having a sufficiently high water retention property and a large particle size without using a special material, which process has steps of (1) a polymerization step for producing primary particles of a water absorbing resin comprising suspending an aqueous monomer solution containing an unsaturated carboxylate in an organic solvent containing a nonionic surfactant therein, and subjecting the resulting suspension to reverse-phase suspension polymerization; and (2) an agglomeration step of agglomerating the primary particles by using a water soluble solvent.

Abstract: A water-absorbing resin has a polymer molecular chain in which 50 mol % or more of repeating units in the chain are carboxy group-containing units, wherein the carboxy group neutralization ratio in the central part of the resin is 60 mol % or more and the carboxy group neutralization ratio on the external surface of the resin is 50 mol % or less. A method for producing the water-absorbing resin comprises polymerizing a monomer solution to form a polymer, drying the resulting polymer, and heat-treating the dried polymer, wherein the monomer solution contains a mixture comprising an alkali metal salt of an unsaturated carboxylic acid and an ammonium salt thereof, the percentage of the ammonium salt being more than 50 mol % of the mixture, and further contains a condensation crosslinking agent.

Abstract: Provided are a manufacturing method of water absorbing resin particle agglomerates capable of producing water absorbing resin particles having a sufficiently high water retention property and a large particle size without using a special material, which process has steps of (1) a polymerization step for producing primary particles of a water absorbing resin comprising suspending an aqueous monomer solution containing an unsaturated carboxylate in an organic solvent containing a nonionic surfactant therein, and subjecting the resulting suspension to reverse-phase suspension polymerization, and (2) an agglomeration step of agglomerating the primary particles by using a water soluble solvent; and water absorbing resin particle agglomerates stably showing a high water retention property and satisfying the following requirements: (a) 50 mol % or greater of repeating units of the polymer molecular chain of the water absorbing resin constituting the primary particles are carboxyl group-containing units and at least

Abstract: A water-absorbing resin has a polymer molecular chain in which 50 mol % or more of repeating units in the chain are carboxy group-containing units, wherein the carboxy group neutralization ratio in the central part of the resin is 60 mol % or more and the carboxy group neutralization ratio on the external surface of the resin is 50 mol % or less. A method for producing the water-absorbing resin comprises polymerizing a monomer solution to form a polymer, drying the resulting polymer, and heat-treating the dried polymer, wherein the monomer solution contains a mixture comprising an alkali metal salt of an unsaturated carboxylic acid and an ammonium salt thereof, the percentage of the ammonium salt being more than 50 mol % of the mixture, and further contains a condensation crosslinking agent.