# US 6,720,389 B2 · Water-absorbent resin and production process therefor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 6,720,389 B2 - Document ID: US6720389B2 - Status: Granted - Kind: B2 - Application number: 09/945,812 - Filed: 2001-09-05 - Published: 2002-05-23 - Granted: 2004-04-13 - Earliest claimed: 2000-09-20 - Assignees: Nippon Shokubai Co., Ltd. - Inventors: Takumi Hatsuda; Yoshio Irie; Masatoshi Nakamura; Katsuyuki Wada; Shinichi Fujino; Kazuki Kimura; Kunihiko Ishizaki - Web page: https://patentgrep.com/patent/US6720389B2 ## CPC - C08J 3/122: {Pulverisation by spraying} - A61L 15/60: Liquid-swellable gel-forming materials, e.g. super-absorbents - C08J 3/245: {Differential crosslinking of one polymer with one crosslinking type, e.g. surface crosslinking} - C08J 2300/14: Water soluble or water swellable polymers, e.g. aqueous gels - Y10S 524/916: Hydrogel compositions - Y10T 428/2982: Particulate matter [e.g., sphere, flake, etc.] - C08J: WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H (working, e.g. shaping, of plastics B29) - 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) - Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract In a production process for a water-absorbent resin, comprising the steps of: blending a liquid material and a water-absorbent resin; and heating the resultant mixture in order to produce a modified water-absorbent resin, the present invention is to provide: a method for uniformly and efficiently treating a water-absorbent resin favorably in view of industry, and as a result, a good-balanced water-absorbent resin having various excellent properties, such absorption capacity without a load, absorption capacity under a load, and single-layer absorption capacity under a load in contact with an aqueous liquid. The production process comprises the step of spray-blending a water-absorbent resin (A) and a liquid material (B) with a blending apparatus equipped with a spray nozzle (C), wherein the liquid material (B) is sprayed from the spray nozzle (C) and its spray pattern is a circular and hollow cone shape or a double-convex-lens and elliptic cone shape. In addition, the production process comprises the step of heat-treating a water-absorbent resin under an atmosphere having a dew point of not higher than 60° C. and a temperature of not lower than 90° C., wherein the water-absorbent resin is obtained after a drying step following a pulverization step. ## Claims ### Claim 1 A production process for a water-absorbent resin, comprising the steps of: blending a liquid material and a water-absorbent resin; and heating the resultant mixture to produce a modified water-absorbent resin, with the production process comprising the step of spray-blending a water-absorbent resin (A) and a liquid material (B) with a blending apparatus equipped with a spray nozzle (C), and spraying the liquid material (B) from the spray nozzle (C) in a circular and hollow cone shaped spray pattern. ### Claim 2 A production process for a water-absorbent resin, comprising the steps of: blending a liquid material and a water-absorbent resin; and heating the resultant mixture to produce a modified water-absorbent resin, with the production process comprising the step of spray-blending a water-absorbent resin (A) and a liquid material (B) with a blending apparatus equipped with a spray nozzle (C), and spraying the liquid material (B) from the spray nozzle (C) in a double-convex-lens and elliptical shaped spray pattern, wherein said spray nozzle (C) is attached to said blending apparatus to form a spray angle of not less than 50° onto an area on said water-absorbent resin, when said dispersing area of a spray-dispersing state is projected onto a sectional area perpendicular to a transfer direction of said water absorbent resin. ### Claim 3 A production process for a water-absorbent resin, comprising the steps of: blending a liquid material (B) and a water-absorbent resin (A); and heating the resultant mixture to produce a modified water-absorbent resin, with the production process comprising the step of heat-treating said mixture of water-absorbent resins (A) and liquid material (B) under an atmosphere having a dew point of not higher 60° C. and a temperature of not lower than 90° C., wherein the modified water-absorbent resin is obtained after a drying step following a pulverization step. ### Claim 4 A production process for a water-absorbent resin, comprising the steps of: blending a liquid material and a water-absorbent resin; and heating the resultant mixture to produce a modified water-absorbent resin, with the production process comprising the steps of: spray-blending a water-absorbent resin (A) and a liquid material (B) with a blending apparatus equipped with a spray nozzle (C); and heat-treating, wherein the liquid material (B) is sprayed from the spray nozzle (C) in a circular and hollow cone shaped spray pattern in the spray-blending step, and wherein the heat-treating step is carried out under an atmosphere having a dew point of not higher than 60° C. and a temperature of not lower than 90° C. ### Claim 5 A production process for a water-absorbent resin, comprising the steps of: blending a liquid material and a water-absorbent resin; and heating the resultant mixture in order to produce a modified water-absorbent resin, with the production process comprising the steps of: spray-blending a water-absorbent resin (A) and a liquid material (B) with a blending apparatus equipped with a spray nozzle (C); and heat-treating, wherein the liquid material (B) is sprayed from the spray nozzle (C) in a double-convex-lens and elliptical cone shaped spray pattern in the spray-blending step, and wherein the heat-treating step is carried out under an atmosphere having a dew point of not higher than 60° C. and a temperature of not lower than 90° C., and wherein said spray nozzle (C) is attached to said blending apparatus to form a spray angle of not less than 50° onto an area on said water-absorbent resin, when said dispersing area of a spray-dispersing state is projected onto a sectional area perpendicular to a transfer direction of said water absorbent resin. ### Claim 6 (depends on 1) A production process for a water-absorbent resin according to claim 1, wherein the maximum spray angle of the liquid material (B) from the spray nozzle (C) is not less than 50° C. ### Claim 7 (depends on 1) A production process for a water-absorbent resin according to claim 1, wherein the blending apparatus equipped with the spray nozzle (C) is a continuous blending apparatus comprising an agitation shaft having a plurality of paddles. ### Claim 8 (depends on 7) A production process for a water-absorbent resin according to claim 7, wherein the area of a spray-dispersing state of the liquid material (B) projected onto a sectional area which is perpendicular to the axis direction of the blending apparatus and includes a spraying point of the spray nozzle (C) accounts for not less than 70% of the sectional area perpendicular to the axis direction of the blending apparatus. ### Claim 9 (depends on 1) A production process for a water-absorbent resin according to claim 1, wherein the blending apparatus is equipped with the plurality of spray nozzles (C). ### Claim 10 (depends on 1) A production process for a water-absorbent resin according to claim 1, wherein the liquid material (B) is an aqueous solution of a surface-crosslinking agent which forms a covalent bond by reacting with a functional group of the water-absorbent resin (A), and which further comprises the step of heat-treating the mixture resultant from the blending step at a water-absorbent resin temperature of 80 to 250° C. ### Claim 11 (depends on 10) A production process for a water-absorbent resin according to claim 10, wherein the liquid material (B) is an aqueous solution including at least one material selected from the group consisting of polyhydric alcohols, polyglycidyl compounds, 1,3-dioxolan-2-on, poly(2-oxazolidinone), bis(2-oxazolidinone), and mono(2-oxazolidinone). ### Claim 12 (depends on 11) A production process for a water-absorbent resin according to claim 11, wherein the liquid material (B) is an aqueous surface-crosslinking agent solution including a polyhydric alcohol. ### Claim 13 (depends on 2) A production process for a water-absorbent resin according to claim 2, wherein the blending apparatus equipped with the spray nozzle (C) is a continuous blending apparatus comprising an agitation shaft having a plurality of paddles. ### Claim 14 (depends on 13) A production process for a water-absorbent resin according to claim 13, wherein the area of a spray-dispersing state of the liquid material (B) projected onto a sectional area which is perpendicular to the axis direction of the blending apparatus and includes a spraying point of the spray nozzle (C) accounts for not less than 70% of the sectional area perpendicular to the axis direction of the blending apparatus. ### Claim 15 (depends on 2) A production process for a water-absorbent resin according to claim 2, wherein the blending apparatus is equipped with the plurality of spray nozzles (C). ### Claim 16 (depends on 2) A production process for a water-absorbent resin according to claim 2, wherein the liquid material (B) is an aqueous solution of a surface-crosslinking agent which forms a covalent bond by reacting with a functional group of the water-absorbent resin (A), and which further comprises the step of heat-treating the mixture resultant from the blending step at a water-absorbent resin temperature of 80 to 250° C. ### Claim 17 (depends on 16) A production process for a water-absorbent resin according to claim 16, wherein the liquid material (B) is an aqueous solution including at least one material selected from the group consisting of polyhydric alcohols, polyglycidyl compounds, 1,3-dioxolan-2-on, poly(2-oxazolidinone), bis(2-oxazolidinone), and mono(2-oxazolidinone). ### Claim 18 (depends on 17) A production process for a water-absorbent resin according to claim 17, the liquid material (B) is an aqueous surface-crosslinking agent solution including a polyhydric alcohol. ### Claim 19 (depends on 3) A production process for a water-absorbent resin according to claim 3, wherein the liquid material (B) is spray-blended with a blending apparatus equipped with a spray nozzle (C). ### Claim 20 (depends on 19) A production process for a water-absorbent resin according to claim 19, wherein the maximum spray angle of the liquid material (B) from the spray nozzle (C) is not less than 50°. ### Claim 21 (depends on 19) A production process for a water-absorbent resin according to claim 19, the blending apparatus equipped with the spray nozzle (C) is a continuous blending apparatus comprising an agitation shaft having a plurality of paddles. ### Claim 22 (depends on 21) A production process for a water-absorbent resin according to claim 21, wherein the area of a spray-dispersing state of the liquid material (B) projected onto a sectional area which is perpendicular to the axis direction of the blending apparatus and includes a spraying point of the spray nozzle (C) accounts for not less than 70% of the sectional area perpendicular to the axis direction of the blending apparatus. ### Claim 23 (depends on 19) A production process for a water-absorbent resin according to claim 19, wherein the blending apparatus is equipped with the plurality of spray nozzles (C). ### Claim 24 (depends on 3) A production process for a water-absorbent resin according to claim 3, wherein the liquid material (B) is an aqueous solution of a surface-crosslinking agent which forms a covalent bond by reacting with a functional group of the water-absorbent resin (A), and which further comprises the step of heat-treating the mixture resultant from the blending step at a water-absorbent resin temperature of 80 to 250° C. ### Claim 25 (depends on 24) A production process for a water-absorbent resin according to claim 24, wherein the liquid material (B) is an aqueous solution including at least one material selected from the group consisting of polyhydric alcohols, polyglycidyl compounds, 1,3-dioxolan-2-on, poly(2-oxazolidinone), bis(2-oxazolidinone), and mono(2-oxazolidinone). ### Claim 26 (depends on 25) A production process for a water-absorbent resin according to claim 25, the liquid material (B) is an aqueous surface-crosslinking agent solution including a polyhydric alcohol. ### Claim 27 (depends on 4) A production process for a water-absorbent resin according to claim 4, wherein the maximum spray angle of the liquid material (B) from the spray nozzle (C) is not less than 50°. ### Claim 28 (depends on 4) A production process for a water-absorbent resin according to claim 4, wherein the blending apparatus equipped with the spray nozzle (C) is a continuous blending apparatus comprising an agitation shaft having a plurality of paddles. ### Claim 29 (depends on 28) A production process for a water-absorbent resin according to claim 28, the area of a spray-dispersing state of the liquid material (B) projected onto a sectional area which is perpendicular to the axis direction of the blending apparatus and includes a spraying point of the spray nozzle (C) accounts for not less than 70% of the sectional area perpendicular to the axis direction of the blending apparatus. ### Claim 30 (depends on 4) A production process for a water-absorbent resin according to claim 4, wherein the blending apparatus is equipped with the plurality of spray nozzles (C). ### Claim 31 (depends on 4) A production process for a water-absorbent resin according to claim 4, wherein the liquid material (B) is an aqueous solution of a surface-crosslinking agent which forms a covalent bond by reacting with a functional group of the water-absorbent resin (A), and which further comprises the step of heat-treating the mixture resultant from the blending step at a water-absorbent resin temperature of 80 to 250° C. ### Claim 32 (depends on 21) A production process for a water-absorbent resin according to claim 21, wherein the liquid material (B) is an aqueous solution including at least one material selected from the group consisting of polyhydric alcohols, polyglycidyl compounds, 1,3-dioxolan-2-on, poly(2-oxazolidinone), bis(2-oxazolidinone), and mono(2-oxazolidinone). ### Claim 33 (depends on 32) A production process for a water-absorbent resin according to claim 32, the liquid material (B) is an aqueous surface-crosslinking agent solution including a polyhydric alcohol. ### Claim 34 (depends on 5) A production process for a water-absorbent resin according to claim 5, wherein the blending apparatus equipped with the spray nozzle (C) is a continuous blending apparatus comprising an agitation shaft having a plurality of paddles. ### Claim 35 (depends on 34) A production process for a water-absorbent resin according to claim 34, wherein the area of a spray-dispersing state of the liquid material (B) projected onto a sectional area which is perpendicular to the axis direction of the blending apparatus and includes a spraying point of the spray nozzle (C) accounts for not less than 70% of the sectional area perpendicular to the axis direction of the blending apparatus. ### Claim 36 (depends on 5) A production process for a water-absorbent resin according to claim 5, wherein the blending apparatus is equipped with the plurality of spray nozzles (C). ### Claim 37 (depends on 5) A production process for a water-absorbent resin according to claim 5, wherein the liquid material (B) is an aqueous solution of a surface-crosslinking agent which forms a covalent bond by reacting with a functional group of the water-absorbent resin (A), and which further comprises the step of heat-treating the mixture resultant from the blending step at a water-absorbent resin temperature of 80 to 250° C. ### Claim 38 (depends on 37) A production process for a water-absorbent resin according to claim 37, wherein the liquid material (B) is an aqueous solution including at least one material selected from the group consisting of polyhydric alcohols, polyglycidyl compounds, 1,3-dioxolan-2-on, poly(2-oxazolidinone), bis(2-oxazolidinone), and mono(2-oxazolidinone). ### Claim 39 (depends on 38) A production process for a water-absorbent resin according to claim 38, the liquid material (B) is an aqueous surface-crosslinking agent solution including a polyhydric alcohol.