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AssigneeNippon Shokubai Co., Ltd.
InventorsShinichi Fujino, Satoshi Matsumoto, Kunihiko Ishizaki
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The physical properties of a water-absorbing resin with low residual monomer content are improved or stabilized, without sacrifices in productivity, production cost, stability, etc. Provided is a water-absorbing resin with low residual monomer content and excellent whiteness, wherein a water-absorbing resin consumed in large quantities in disposable diapers, etc., is preferably a sustainable and renewable water-absorbing resin that does not require excessive purification of the acrylic acid, particularly acrylic acids derived from non-fossil sources, that is the starting material of the water-absorbing resin. Disclosed is a method of manufacturing a hydrophilic polyacrylic acid (salt) resin, which is a method of manufacturing a water-absorbing polyacrylic acid resin that comprises a step in which a monomer is prepared from acrylic acid, a step in which said monomer is polymerized, and a step in which the resulting hydrous gel is dried. The polymerization is performed such that the content of hydroxypropionic acid (salt) in the monomer is 2000 ppm or less and/or the content of saturated organic carboxylic acid in the monomer is 2% by mass or less, and at least a portion of the saturated organic carboxylic acid is volatilized during and after the drying step.
A method of manufacturing a hydrophilic polyacrylic acid (salt) resin selected from the group consisting of a water-absorbent resin and a water-soluble resin, comprising the steps of:
Dependencies are inferred from the claim text.