| abstract |
As a property that has not been known at all, the “puffing efficiency under pressure (PPUP)” of the particulate water-absorbing agent is controlled, and further, “particle size” and “coloring” are simultaneously controlled. The present invention is a particulate water-absorbing agent that satisfies the following (a) to (c). (A) Liquid passing efficiency under pressure (PPUP) is 50 to 100%. (B) Yellowness (YI) is 0 to 10, and a yellowness change rate (ΔYI) after a color acceleration test for 14 days at 70 ± 1 ° C. and 95 ± 1% relative humidity is 100 to 150%. (C) 0 to 5% by mass of particles less than 150 μm, 200 to 550 μm in mass average particle diameter (D50), and logarithmic standard deviation (σζ) of particle size distribution of 0.20 to 0 as defined by standard sieve classification .40. |