# US 2013/0158495 A1 · Water absorbent resin and method for producing same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2013/0158495 A1 - Document ID: US20130158495A1 - Status: Published application - Kind: A1 - Application number: 13/816,586 - Filed: 2011-09-02 - Published: 2013-06-20 - Earliest claimed: 2010-09-06 - Assignees: Sumitomo Seika Chemicals Co., Ltd. - Inventors: Masayoshi Handa; Yuichi Onoda; Koji Ueda - Web page: https://patentgrep.com/patent/US20130158495A1 ## CPC - B01J 20/28016: {Particle form} - A61F 13/53: characterised by the absorbing medium (A61F13/20 takes precedence) - A61L 15/22: containing macromolecular materials - A61L 15/60: Liquid-swellable gel-forming materials, e.g. super-absorbents - C08F 2/32: Polymerisation in water-in-oil emulsions - C08F 20/06: Acrylic acid; Methacrylic acid; Metal salts or ammonium salts thereof - A61F 2013/530481: {having superabsorbent materials, i.e. highly absorbent polymer gel materials} - Y10T 428/2982: Particulate matter [e.g., sphere, flake, etc.] - B01J: CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS - A61F: FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS (dental prosthetics A61C) - A61L: METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES (preservation of bodies or disinfecting characterised by the agents employed A01N; preserving, e.g. sterilising, food or foodstuffs A23; preparations for medical, dental or toiletry purposes A61K) - C08F: MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract Object The main object of the present invention is to provide a water-absorbent resin having a suitable particle size, strong particle strength, excellent adhesion to fibers, and excellent flowability as powders as well as properties suitable for a water-absorbent material used in a hygienic material, such as excellent general absorption properties as a water-absorbent resin, and to provide a process for producing the same. Another object of the present invention is to provide an absorbent material and an absorbent article using the water-absorbent resin. Means for Achieving the Object A water-absorbent resin having an aspect ratio of 1.0 to 3.0 and a median particle size (D) of 100 to 2,000 μm in which primary particles having an aspect ratio of 1.1 to 200 and a median particle size (d) of 50 to 600 μm are agglomerated. ## Claims ### Claim 1 A water-absorbent resin in the form of a secondary particle in which primary particles having an aspect ratio of 1.1 to 200 and a median particle size (d) of 50 to 600 μm are agglomerated, the secondary particle having an aspect ratio of 1.0 to 3.0 and a median particle size (D) of 100 to 2,000 μm. ### Claim 2 (depends on 1) The water-absorbent resin according to claim 1, wherein the water-absorbent resin has a particle size uniformity of 1.0 to 2.2. ### Claim 3 (depends on 1) The water-absorbent resin according to claim 1, wherein the water-absorbent resin has a flow index of 70 to 200 and an index of adhesion to fibers of 50 to 100. ### Claim 4 (depends on 1) The water-absorbent resin according to claim 1, wherein the primary particles have a form comprising a curved surface. ### Claim 5 (depends on 1) The water-absorbent resin according to claim 1 produced by using a reversed phase suspension polymerization method comprising steps 1 and 2 described below: (1) step 1, in which a water-soluble ethylenically unsaturated monomer is subjected to a polymerization reaction in the presence of a thickener and a dispersion stabilizer to form a slurry in which primary particles are dispersed, and (2) step 2, in which the slurry obtained in step 1 is cooled to precipitate the dispersion stabilizer, and then a water-soluble ethylenically unsaturated monomer is further added to perform a polymerization reaction, thereby agglomerating the primary particles dispersed in the slurry to form the water-absorbent resin in the form of a secondary particle. ### Claim 6 (depends on 1) An absorbent material comprising the water-absorbent resin according to claim 1 and a hydrophilic fiber. ### Claim 7 (depends on 6) An absorbent article including the absorbent material according to claim 6 between a liquid-permeable sheet and a liquid-impermeable sheet. ### Claim 8 A method for producing a water-absorbent resin comprising a secondary particle according to a reversed phase suspension polymerization method including steps 1 and 2 described below: (1) step 1, in which a water-soluble ethylenically unsaturated monomer is subjected to a polymerization reaction in the presence of a thickener and a dispersion stabilizer to form a slurry in which primary particles are dispersed, and (2) step 2, in which the slurry obtained in step 1 is cooled to precipitate the dispersion stabilizer, and then a water-soluble ethylenically unsaturated monomer is further added to perform a polymerization reaction, thereby agglomerating the primary particles dispersed in the slurry to form the water-absorbent resin in the form of the secondary particle.