METHOD FOR PRODUCING WATER-ABSORBENT RESIN PARTICLES AND WATER-ABSORBENT RESIN PARTICLES

• Main Authors: HEGURI ATSUSHI, ONODA YUICHI, TANIMURA KENJI
• Format: Patent
• Language: English; French; German
• Published: 19.08.2015
• Subjects: AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F,C08G; CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOIDCHEMISTRY; CHEMISTRY; COMPOSITIONS BASED THEREON; GENERAL PROCESSES OF COMPOUNDING; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVINGCARBON-TO-CARBON UNSATURATED BONDS; METALLURGY; ORGANIC MACROMOLECULAR COMPOUNDS; PERFORMING OPERATIONS; PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL; TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION; TECHNICAL SUBJECTS COVERED BY FORMER USPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS; THEIR PREPARATION OR CHEMICAL WORKING-UP; THEIR RELEVANT APPARATUS; TRANSPORTING; WORKING-UP

The present invention provides a method for producing water-absorbent resin particles which show an excellent water absorption rate and high equilibrium swelling capacity and which have an appropriate particle size to be excellent in handleability, and water-absorbent resin particles obtained by the method. The present invention is a method for producing water-absorbent resin particles by reversed phase suspension polymerization of a water-soluble ethylenically unsaturated monomer, the method including the steps of: (A) first reversed phase suspension polymerization of a water-soluble ethylenically unsaturated monomer in a petroleum hydrocarbon dispersion medium using a water-soluble radical polymerization initiator, in the absence of an internal crosslinking agent and in the presence of a surfactant having an HLB of 8 to 12; (B) intermediate crosslinking reaction by adding an intermediate crosslinking agent; (C) second reversed phase suspension polymerization of a water-soluble ethylenically unsaturated monomer added to the petroleum hydrocarbon dispersion medium containing the surfactant dissolved therein using a water-soluble radical polymerization initiator in the absence of an internal crosslinking agent, thereby producing a water-absorbent resin precursor; and (D) post crosslinking reaction of the water-absorbent resin precursor preliminary adjusted to have a moisture content of 30 to 100% by mass relative to a water-soluble ethylenically unsaturated monomer component in the water-absorbent resin precursor.