Particulate water-absorbing agent and method for producing the same

Abstract

[Problem] In an embodiment involving addition of a chelating agent in an upstream process of the process for production, such as the polymerization step, the residual ratio of the chelating agent in the final product, a particulate water-absorbing agent, is improved. [Solution] A particulate water-absorbing agent having a poly(meth)acrylic acid (salt)-based water-absorbing resin as a main component, containing a chelating agent having a nitrogen atom and an inorganic reducing agent having a sulfur atom, wherein the particulate water-absorbing agent has a chelating agent ratio of 0.8 to 1.8, as calculated by the following procedures (a) to (c): (a) subjecting the particulate water-absorbing agent to a predetermined impact test; (b) sieving the particulate water-absorbing agent subjected to the impact test into a particle group 1 with a particle size of less than 300 μm and a particle group 2 with a particle size of 300 μm or more and less than 850 μm using a JIS standard sieve; and (c) quantifying a content C1 of the chelating agent present in the particle group 1 and a content C2 of the chelating agent present in the particle group 2, and then dividing the C1 by the C2.