METHOD FOR PRODUCING WATER-ABSORBING RESIN

• Main Authors: UEDA, KOJI, ONODA, YUICHI, TAKATORI, JUNICHI, ISOKAWA, SHO
• Format: Patent
• Language: English; French; German
• Published: 23.10.2013
• Subjects: CHEMISTRY; COMPOSITIONS BASED THEREON; MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVINGCARBON-TO-CARBON UNSATURATED BONDS; METALLURGY; ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP

Object The main object of the present invention is to provide a method for producing water-absorbent resin having reduced discoloration resulting from high-temperature treatment, small amounts of fine powder and coarse powder, and a narrow particle size distribution. Means for achieving the object A method for producing water-absorbent resin, comprising: (1) Step 1, in which a water-soluble ethylenically unsaturated monomer is subjected to a reversed-phase suspension polymerization in a petroleum hydrocarbon dispersion medium in which a surfactant is dissolved, thereby forming a slurry in which primary particles are dispersed, and (2) Step 2, in which the slurry obtained in Step 1 is cooled to partially precipitate the surfactant, and then a (water-soluble ethylenically unsaturated monomer is polymerized in the slurry to agglomerate the primary particles, thereby forming water-absorbent resin, wherein the surfactant is a sucrose fatty acid ester in which the monoester content is 25% by mass or less, the tetraester content is 10% by mass or more, and the content of tetra or higher esters is 30% by mass or less.