# US 5,180,622 A · Absorbent members containing interparticle crosslinked aggregates > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,180,622 A - Document ID: US5180622A - Status: Granted - Kind: A - Application number: 07/503,500 - Filed: 1990-04-02 - Granted: 1993-01-19 - Earliest claimed: 1990-04-02 - Assignees: The Procter & Gamble Company - Inventors: Charles J. Berg; Donald C. Roe; Frank H. Lahrman - Web page: https://patentgrep.com/patent/US5180622A ## CPC - A61F 13/535: inhomogeneous in the plane of the pad, e.g. core absorbent layers being of different sizes ({A61F13/5323,} A61F13/537 take precedence) - A61F 13/53717: {the layer having a promotional function on liquid propagation in the horizontal direction} - A61F 13/53747: {the layer is facing the topsheet (layer is part of the topsheet A61F13/511)} - A61F 13/53752: {the layer is embedded in the absorbent core} - A61L 15/60: Liquid-swellable gel-forming materials, e.g. super-absorbents - A61F 13/49: specially adapted to be worn around the waist, e.g. diapers or nappies - A61F 13/51: characterised by the outer layers of the pads (A61F13/20 takes precedence) - A61F 13/533: having discontinuous areas of compression - A61F 2013/15284: {characterized by quantifiable properties} - A61F 2013/15365: {Dimensions} - A61F 2013/15821: {characterized by the apparatus for manufacturing} - A61F 2013/49031: {being elastic in longitudinal direction} - A61F 2013/49033: {being elastic in transversal direction} - A61F 2013/5103: {being hydrophobic} - A61F 2013/51409: {being a film} - A61F 2013/51411: {being impervious to fluids but not for air or vapours} - A61F 2013/5149: {being embossed} - A61F 2013/530007: {being made from pulp} - A61F 2013/530496: {being fixed to fibres} - A61F 2013/53051: {being only in particular parts or specially arranged} - A61F 2013/530518: {the maximum being at the crotch} - A61F 2013/530532: {the maximum being at certain depth in the thickness} - A61F 2013/53054: {the maximum being along the side edges} - A61F 2013/530547: {positioned in a separate layer or layers} - A61F 2013/530569: {characterized by the particle size} - A61F 2013/530598: {in aggregates} - A61F 2013/5307: {characterized by the quantity or ratio of superabsorbent material} - A61F 2013/530766: {by the cross-link factor} - A61F 2013/53445: {from several sheets} - A61F 2013/53795: {being a surge management layer} - A61F 2013/8488: {including testing apparatus} - A61F 2013/8491: {including test methods} - Y10S 428/913: Material designed to be responsive to temperature, light, moisture - Y10T 428/24777: Edge feature - Y10T 428/24992: Density or compression of components - Y10T 428/253: Cellulosic [e.g., wood, paper, cork, rayon, etc.] - Y10T 428/254: Polymeric or resinous material - Y10T 442/699: Including particulate material other than strand or fiber material - 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) - Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract Absorbent members incorporating particulate, absorbent, polymeric compositions comprising interparticle crosslinked aggregates. The interparticle crosslinked aggregates comprise precursor particles of substantially water-insoluble, absorbent, hydrogen-forming, polymer material; and an interparticle crosslinking agent reacted with the polymer material of the precursor particles to form crosslink bonds between the precursor particles. The absorbent members of the present invention can comprise a combination of fiber material and discrete particles of the polymeric composition or laminates (layered absorbent members) containing such polymeric compositions. The performance of absorbent members is enhanced by the use of such polymeric compositions due to the high rate of fluid uptake and minimal gel blocking properties of the interparticle crosslinked aggregates. ## Claims ### Claim 1 An absorbent member comprising a mixture of fiber material and a particulate, absorbent, polymeric composition, said polymeric composition comprising interparticle crosslinked aggregates, said interparticle crosslinked aggregates comprising (i) precursor particles of substantially water-insoluble, absorbent, hydrogel-forming, polymer material, and (ii) an interparticle crosslinking agent reacted with said polymer material of said precursor particles to form covalent crosslink bonds between said precursor particles, said interparticle crosslinked aggregates being present in said polymeric composition in an amount such that said polymeric composition has a mass average particle size at least about 25% greater than the mass average particle size of said precursor particles. ### Claim 2 (depends on 1) The absorbent member of claim 1 wherein said fiber material comprises hydrophilic fiber material. ### Claim 3 (depends on 2) The absorbent member of claim 2 wherein said hydrophilic fiber material comprises wood pulp fibers. ### Claim 4 (depends on 1) The absorbent member of claim 1 wherein said polymeric composition is uniformly distributed throughout the absorbent member. ### Claim 5 (depends on 4) The absorbent member of claim 4 having a density of from about 0.06 g/cm.sup.3 to about 0.3 g/cm.sup.3. ### Claim 6 (depends on 1) The absorbent member of claim 1 wherein said polymeric composition has a mass average particle size at least about 30% greater than the mass average particles size of said precursor particles. ### Claim 7 (depends on 1) The absorbent member of claim 1 wherein said polymeric composition has a mass average particle size at least about 50% greater than the mass average particle size of said precursor particles. ### Claim 8 (depends on 1, 6) The absorbent member of claim 1, 6, or 7 wherein the mass average particle size of said precursor particles is less than about 600 microns. ### Claim 9 (depends on 1) The absorbent member of claim 1 having a fiber/polymeric composition weight ratio of from about 95:5 to about 25:75. ### Claim 10 (depends on 1) The absorbent member of claim 1 wherein at least about 50% by weight of said polymeric composition comprises interparticle crosslinked aggregates. ### Claim 11 An absorbent member comprising a mixture of fiber material and a particulate, absorbent, polymeric composition, said polymeric composition comprising interparticle crosslinked aggregates, said interparticle crosslinked aggregates comprising (i) substantially dry precursor particles of substantially water-insoluble, absorbent, hydrogel-forming, polymer material; said polymer material of said precursor particles being selected from the group consisting of hydrolyzed starch-acrylonitrile graft copolymer, partially neutralized starch-acrylonitrile graft copolymer, starch-acrylic acid graft copolymer, partially neutralized starch-acrylic acid graft copolymer, saponified vinyl acetate-acrylic ester copolymers, hydrolyzed acrylonitrile or acrylamide copolymers, slightly network crosslinked products of any of the foregoing copolymers, partially neutralized polyacrylic acid, and slightly network crosslinked products of partially neutralized polyacrylic acid; and (ii) an interparticle crosslinking agent reacted with said polymer material of said precursor particles to form covalent crosslink bonds between said precursor particles; said interparticle crosslinking agent being selected from the group consisting of polyhydric alcohol compounds, polyglycidyl ether compounds, polyfunctional aziridine compounds, polyfunctional amine compounds, and polyfunctional isocyanate compounds; said interparticle crosslinked aggregates being present in said polymeric composition in an amount such that said polymeric composition has a mass average particle size at least about 30% greater than the mass average particle size of said precursor particles. ### Claim 12 (depends on 11) The absorbent member of claim 11 said mixture of fiber material and particulate, absorbent, polymeric composition being distributed in zones of different densities, such that the absorbent member comprises an acquisition zone and a storage zone at least partially laterally surrounding the perimeter of said acquisition zone so as to be in liquid communication with at least a portion of the lateral area of said acquisition zone, said acquisition zone having a lower average density and a lower average basis weight per unit area than said storage zone. ### Claim 13 (depends on 12) The absorbent member of claim 12 wherein said acquisition zone extends from the top surface of the absorbent member through at least a fraction of the total thickness of the absorbent member, the top surface of said acquisition zone comprising less than about 50% of the top surface area of the absorbent member. ### Claim 14 (depends on 11) The absorbent member of claim 11 additionally comprising an absorbent acquisition layer juxtaposed on the absorbent member. ### Claim 15 (depends on 14) The absorbent member of claim 14 wherein said absorbent member has a top surface area that is from about 0.25 to about 1.0 times that of said absorbent acquisition layer. ### Claim 16 (depends on 15) The absorbent member of claim 15 wherein said absorbent acquisition layer consists essentially of hydrophilic fiber material. ### Claim 17 (depends on 14) The absorbent member of claim 14 wherein said absorbent acquisition layer has a top surface area that is from about 0.25 to about 1.0 times that of the absorbent member. ### Claim 18 (depends on 17) The absorbent member of claim 17 wherein said absorbent acquisition layer comprises chemically stiffened cellulosic fibers. ### Claim 19 (depends on 11) The absorbent member of claim 11 additionally comprising a dusting layer consisting essentially of hydrophilic fiber material positioned subjacent the absorbent member. ### Claim 20 (depends on 19) The absorbent member of claim 19 wherein said dusting layer is relatively thinner in thickness than the absorbent member. ### Claim 21 (depends on 11) The absorbent member of claim 11 wherein said polymeric composition is uniformly distributed throughout the absorbent member. ### Claim 22 (depends on 11) The absorbent member of claim 11 wherein said polymeric composition is distributed in a positive gradient through at least a portion of the thickness of the absorbent member. ### Claim 23 (depends on 11, 12, 15, 18, 20) The absorbent member of claims 11, 12, 15, 18 or 20 wherein said polymeric composition has a mass average particle size at least about 50% greater than the mass average particle size of said precursor particles. ### Claim 24 An absorbent member having a back section and a front section contiguous with said back section, said front section having an end region and a deposition region contiguous with said end region and said back section so that said deposition region is positioned between said end region and said back section, the absorbent member comprising: a mixture of hydrophilic fiber material and a particulate, absorbent, polymeric composition, said polymeric composition comprising interparticle crosslinked aggregates, said interparticle crosslinked aggregates comprising (i) substantially dry precursor particles of substantially water-insoluble, absorbent, hydrogel-forming, polymer material, said polymer material consisting essentially of slightly network crosslinked products of partially neutralized polyacrylic acid; and (ii) an interparticle crosslinking agent reacted with said polymer material of said precursor particles to form covalent crosslink bonds between said precursor particles; said interparticle crosslinking agent being selected from the group consisting of glycerol, trimethylol propane, ethylene glycol, 1,2-propanediol, or 1,3-propanediol; said interparticle crosslinked aggregates being present in said polymeric composition in an amount such that said polymeric composition has a mass average particle size at least about 30% greater than the mass average particle size of said precursor particles, the mass average particle size of said precursor particles being less than about 500 microns; and said mixture of fiber material and particulate, absorbent polymeric composition being distributed in zones of different densities, such that the absorbent member comprises: a storage zone positioned in at least said deposition region of said absorbent member; and an acquisition zone positioned, in at least said deposition region of the absorbent member, said acquisition zone having a lower average density and a lower average basis weight per unit area than said storage zone, said storage zone at least partially laterally surrounding the perimeter of said acquisition zone as to be in liquid communication with at least a portion of the lateral area of said acquisition zone. ### Claim 25 A layered absorbent member comprising: a) n webs of fibrous materials, n being an integer of two or more, said webs being layered such that there is an uppermost web, a lowermost web, n-2 intermediate webs, and n-1 interfaces of two opposed adjacent contacting surfaces of adjacent webs; and b) a particulate, absorbent, polymeric composition forming a layer at one or more of said interfaces, said polymeric composition comprising interparticle crosslinked aggregates, said interparticle crosslinked aggregates comprising (i) substantially dry precursor particles of substantially water-insoluble, absorbent, hydrogel-forming, polymer material, and (ii) an interparticle crosslinking agent reacted with said polymer material of said precursor particles to form covalent crosslink bonds between said precursor particles, said interparticle crosslinked aggregates being present in said polymeric composition in an amount such that said polymeric composition has a mass average particle size at least about 30% greater than the mass average particle size of said precursor particles. ### Claim 26 (depends on 25) The layered absorbent member of claim 25 wherein said polymeric composition is bonded to one or more of said webs. ### Claim 27 (depends on 26) The layered absorbent member of claim 26 wherein said webs comprise absorbent tissue. ### Claim 28 (depends on 27) The layered absorbent member of claim 27 wherein n is between 2 and 12. ### Claim 29 (depends on 28) The layered absorbent member of claim 28 wherein the particles of said polymeric composition are discretely spaced from each other. ### Claim 30 (depends on 25) The layered absorbent member of claim 25 wherein n equals 2 and the edges of said webs are joined together around the periphery of the layered absorbent member. ### Claim 31 (depends on 25, 27, 28) The layered absorbent member of claim 25, 27, 28, or 30 wherein said polymer material of said precursor particles is selected from the group consisting of hydrolyzed starch-acrylonitrile graft copolymer, partially neutralized starch-acrylonitrile graft copolymer, starch-acrylic acid graft copolymer, partially neutralized starch-acrylic acid graft copolymer, saponified vinyl acetate-acrylic ester copolymers, hydrolyzed acrylonitrile or acrylamide copolymers, slightly network crosslinked products of any of the foregoing copolymers, partially neutralized polyacrylic acid, and slightly network crosslinked products of partially neutralized polyacrylic acid; and said interparticle crosslinking agent is selected from the group consisting of polyhydric alcohol compounds, polyglycidyl ether compounds, polyfunctional aziridine compounds, polyfunctional amine compounds, and polyfunctional isocyanate compounds. ### Claim 32 (depends on 31) The layered absorbent member of claim 31 wherein said polymeric composition has a mass average particle size at least about 50% greater than the mass average particle size of said precursor particles.