Hydrophilic resin, absorbent article, and acrylic acid for polymerization

Abstract

The invention provides a hydrophilic resin and an absorbent article, both of which display still less coloring and discoloring when preserved for a long time. The hydrophilic resin is any one of: 1) a hydrophilic resin, obtained by a process including the step of polymerizing a monomer component including a major proportion of either one or both of acrylic acid and its salt which merely have a content of at most 0.20 ppm in total of hydroquinone and benzoquinone; 2) a hydrophilic resin, comprising a major proportion of an acrylic polymer and a minor proportion of either one or both of hydroquinone and benzoquinone, with the hydrophilic resin further comprising a quinhydronation inhibitor of 10˜1,000,000 times the total weight of hydroquinone and benzoquinone; 3) a hydrophilic resin, comprising a major proportion of an acrylic polymer and merely having a coloring degree (YI) of at most 20 after being left under conditions of the open system, 70° C., 65% RH for 1 week; and 4) a hydrophilic resin, which is a water-absorbent resin and is surface-crosslinked or surface-impregnated with a polyhydric alcohol and displays pH of 5.5 or less in a physiological salt solution and has an absorption capacity of 20 g/g or more for a physiological salt solution under a load of 50 g/cm . In addition, the absorbent article comprises the above hydrophilic resin.