ABSORBENT MATERIAL, WATER ABSORBENT AND METHOD FOR PRODUCING WATER ABSORBENT

摘要

The present invention provides: a water absorbent which has a good balance between good physical properties and decrease in the coloring rate with time even if the specific surface area is large and the moisture absorption rate is high; and an absorbent material which has a low pulp ratio and is suitable for thin paper diapers, while achieving a good balance between good physical properties and decrease in the coloring rate with time.　An absorbent material which contains a hydrophilic base material and a water absorbent, wherein: the water absorbent contains surface-crosslinked amorphous crushed water absorbent resin particles, an α-hydroxycarboxylic acid (salt) and an aminocarboxylic acid-based chelating agent and/or a phosphorus-based chelating agent; if the amount (x₁ mol%) of the α-hydroxycarboxylic acid (salt) extracted from the water absorbent is plotted on the x-axis and the amount (y₁ mmol%) of the aminocarboxylic acid-based chelating agent and/or the phosphorus-based chelating agent extracted from the water absorbent is plotted on the y-axis, the plotted points are present within the range that satisfies a specific relational expression of x₁ and y₁; and the water absorbent has a moisture absorption rate of 120 mg/g/hr or more at a temperature of 40 ± 1°C at a relative humidity of 75 ± 1% RH.