Patent ID: 8729191

Claim:
A process for producing a polyacrylic acid (salt) water-absorbent resin by polymerizing an acrylic acid composition including acrylic acid and/or its salt as a main component, the process comprising (a) a step of neutralizing the acrylic acid included in the acrylic acid composition with a basic composition; and then polymerizing a resultant product, thereby forming a hydrogel crosslinked polymer, wherein the acrylic acid included in the acrylic acid composition comprises: (i) a methoxyphenol content of 10 to 200 ppm by weight relative to the weight of the acrylic acid; (ii) at least one compound content of which is 0 to 10 ppm by weight relative to the weight of the acrylic acid, the compound being selected from the group consisting of protoanemonin and furfural; and (iii) β-hydroxypropionic acid and/or acrylic acid dimer in an amount of 1 to 1000 ppm by weight relative to the weight of the acrylic acid; the basic composition including a basic compound and iron, the basic composition having an iron content of 0.14 to 3.5 ppm by weight, and the water-absorbent resin having a liquid permeability under pressure (PPUP) in a range of 50 to 100%.