# US 5,877,097 A · Densified cellulose fiber pads and method of making the same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,877,097 A - Document ID: US5877097A - Status: Granted - Kind: A - Application number: 08/552,593 - Filed: 1995-11-03 - Granted: 1999-03-02 - Earliest claimed: 1994-11-10 - Assignees: Weyerhaeuser Company - Inventors: Hugh West; Colin Elston; Fred B. Howard - Web page: https://patentgrep.com/patent/US5877097A ## CPC - A61F 13/53747: {the layer is facing the topsheet (layer is part of the topsheet A61F13/511)} - A61F 13/15203: {Properties of the article, e.g. stiffness or absorbency (chemical aspects A61L15/00)} - D04H 1/425: Cellulose series - D04H 1/54: by welding together the fibres, e.g. by partially melting or dissolving (in combination with needling D04H1/485) - D04H 1/60: the bonding agent being applied in dry state, e.g. thermo-activatable agents in solid or molten state, and heat being applied subsequently - A61F 2013/15422: {Density} - A61F 2013/530182: {characterized by the connection between the fibres} - A61F 2013/530248: {being thermosetting fibres} - Y10T 442/60: Nonwoven fabric [i.e., nonwoven strand or fiber material] - Y10T 442/659: Including an additional nonwoven fabric - Y10T 442/673: Including particulate material other than fiber - 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) - D04H: MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL (weaving D03; knitting D04B; braiding D04C; net-making D04G; sewing D05B; tufting D05C; finishing non-woven fabrics D06); FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING {; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION}(non-woven fabrics having an intermediate or external layer of a different kind, e.g. of woven fabric, B32B) - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract A densified web of cellulose fibers has a high absorbent capacity and good wet strength. The web is produced by combining cellulose fibers with a bonding agent, activating the bonding agent, allowing it to contact the cellulose fibers, and thereafter deactivating the bonding agent. The web is thereafter compressed in a cooled state to form a densified web. The web exhibits an absorbent capacity superior to that of prior densified and bonded webs. ## Claims ### Claim 1 A fibrous article comprising: a densified web of cellulose fibers, at least some of said fibers being bonded together by an activatable bonding agent comprising a water insoluble thermoplastic or thermosetting material, said densified web having a minimum density at least equal to or greater than 0.1 g/cc, based on the weight of the fiber and bonding material, said web having been densified after the bonding agent has been deactivated and has bound the fibers together, said web having been densified while the bonding agent is deactivated, the densified web having an absorbent capacity for synthetic urine that is greater than the absorbent capacity for synthetic urine exhibited by a comparable web of cellulose fibers bound together by a bonding agent in which the comparable web has been densified to substantially the same degree as said densified web by activating the bonding agent and densifying the comparable web while the bonding agent is active. ### Claim 2 (depends on 1) The article of claim 1, wherein the density of the web ranges from 0.1 g/cc to 0.7 g/cc. ### Claim 3 (depends on 2) The article of claim 2, wherein the density of the web ranges from 0.3 g/cc to 0.7 g/cc. ### Claim 4 (depends on 1) The article of claim 1, wherein the densified web has a wet pad integrity greater than the wet pad integrity of a non-bonded, densified web of cellulose fibers that has been densified to substantially the same degree. ### Claim 5 (depends on 1) The article of claim 1, wherein said article has an absorbent capacity that is at least about equivalent to a non-bonded, densified web of cellulose fibers. ### Claim 6 (depends on 1) The article of claim 1, wherein the article further comprises superabsorbent polymer distributed in said web in an amount effective to increase the absorbency of said web. ### Claim 7 (depends on 6) The article of claim 6, wherein the superabsorbent polymer is present in an amount up to about 70% by weight based on the weight of the fiber and polymer. ### Claim 8 (depends on 1) The article of claim 1, wherein said cellulose fibers are selected from the group consisting of non-cross-linked cellulose fibers, cross-linked cellulose fibers, cellulosic fibers containing a particle binder or a densification/softening agent, and mixtures thereof. ### Claim 9 (depends on 1) The article of claim 1, wherein the bonding agent comprises a thermoplastic or thermosetting material that is activatable by heating to a temperature above room temperature, when heated will contact the cellulose fibers, when deactivated will bond at least some of the cellulosic fibers together. ### Claim 10 (depends on 9) The article of claim 9, wherein the thermosetting material is selected from the group consisting of a phenolic resin, polyvinyl acetate, urea formaldehydes, melamine formaldehydes, and acrylics. ### Claim 11 (depends on 9) The article of claim 9, wherein the thermoplastic material is particles or fibers selected from the group consisting of thermoplastic polymers, cellulosic fibers coated with thermoplastic polymer, and multi-component fibers in which at least one of the components of the fiber comprises a thermoplastic polymer. ### Claim 12 (depends on 11) The article of claim 11, wherein the thermoplastic polymer is selected from the group consisting of polyester, polyethylene and polypropylene. ### Claim 13 A fibrous article comprising: a densified web of cellulose fibers in which at least some of the cellulose fibers are bonded together by a bonding agent comprising a water insoluble, thermoplastic or thermosetting material, said web having been densified after the bonding agent has been deactivated and has bound the fibers together, said web having been densified while the bonding agent is deactivated, the densified web having an absorbent capacity for synthetic urine that is greater than the absorbent capacity for synthetic urine exhibited by a comparable web of cellulose fibers bound together by a bonding agent in which the comparable web has been densified to substantially the same degree as said densified comparable web by activating the bonding agent and densifying the web while the bonding agent is active. ### Claim 14 (depends on 13) The fibrous article of claim 13, wherein the densified web has a wet pad integrity greater than the wet pad integrity of a non-bonded web of cellulose fibers that have been densified to substantially the same degree. ### Claim 15 (depends on 13) The fibrous article of claim 13, wherein said cellulose fibers are selected from the group consisting of cross-linked cellulose fibers, non-cross-linked cellulose fibers, cellalosic fibers containing a particle binder or densification/softening agent, and mixtures thereof. ### Claim 16 (depends on 13) The fibrous article of claim 13, wherein the densified web has an absorbent capacity that is at least about equivalent to the absorbent capacity of a non-bonded, densified web of cellulose fibers. ### Claim 17 (depends on 13) The fibrous article of claim 13, wherein the densified web has a density equal to or greater than 0.1 g/cc. ### Claim 18 (depends on 17) The article of claim 17, wherein the densified web has a density ranging from about 0.1 to about 0.7 g/cc. ### Claim 19 (depends on 18) The article of claim 18, wherein said densified web has a density ranging from about 0.3 to about 0.7 g/cc. ### Claim 20 (depends on 13) The article of claim 13, wherein said densified web further comprises a superabsorbent polymer distributed through said densified web. ### Claim 21 (depends on 20) The article of claim 20, wherein the superabsorbent polymer is present in amounts ranging up to about 70% by weight based on the weight of the fiber and polymer. ### Claim 22 (depends on 13) The article of claim 13, wherein the bonding agent comprises a thermoplastic or thermosetting material that is activatable by heating to a temperature above room temperature, that when heated will contact the cellulose fibers, and when deactivated will bond at least some of the cellulose fibers together. ### Claim 23 (depends on 22) The article of claim 22, wherein the thermoplastic material is selected from the group consisting of particles or fibers comprising a thermoplastic polymer, cellulose fibers coated with a thermoplastic polymer, and multi-component fibers wherein at least one of the fiber components comprises a thermoplastic polymer. ### Claim 24 (depends on 23) The article of claim 23, wherein said thermoplastic polymer is selected from the group consisting of polyester, polypropylene, and polyethylene. ### Claim 25 (depends on 22) The article of claim 22, wherein the thermosetting material is selected from the group consisting of phenolic resin, polyvinyl acetate, urea formaldehydes, melamine formaldehydes, and acrylics. ### Claim 26 An absorbent article for acquiring, distributing, or storing body fluids, the article comprising: an absorbent layer that includes a densified web of cellulose fibers in which at least some of the cellulose fibers are bonded together by a bonding agent comprising a water insoluble, thermoplastic or thermosetting material, said web having been densified after the bonding agent is deactivated and has bound the fibers together, said web having been densified while the bonding agent is deactivated, the densified web having a minimum density equal to or greater than 0.1 g/cc, based on the weight of the cellulose fiber and bonding agent. ### Claim 27 (depends on 26) The fibrous article of claim 26, wherein the densified web has a wet pad integrity greater than the wet pad integrity of a non-bonded web of cellulose fibers that has been densified to substantially the same degree. ### Claim 28 (depends on 26) The fibrous article of claim 26, wherein said cellulose fibers are selected from the group consisting of cross-linked cellulose fibers, non-cross-linked cellulose fibers, cellulosic fibers containing a particle binder or densification/softening agent, and mixtures thereof. ### Claim 29 (depends on 26) The fibrous article of claim 26, wherein the densified web has an absorbent capacity that is at least about equivalent to the absorbent capacity of a non-bonded, densified web of cellulose fibers. ### Claim 30 (depends on 26) The fibrous article of claim 26, wherein the densified web has a density equal to or greater than 0.1 g/cc. ### Claim 31 (depends on 30) The article of claim 30, wherein the densified web has a density ranging from about 0.1 to about 0.7 g/cc. ### Claim 32 (depends on 31) The article of claim 31, wherein said densified web has a density ranging from about 0.3 to about 0.7 g/cc. ### Claim 33 (depends on 26) The article of claim 26, wherein said densified web further comprises a super absorbent polymer distributed through said densified web. ### Claim 34 (depends on 33) The article of claim 33, wherein the superabsorbent polymer is present in amounts ranging up to about 70% by weight based on the weight of the fibers and the bonding agent. ### Claim 35 (depends on 26) The article of claim 26, wherein the bonding agent comprises a thermoplastic or thermosetting material that is activatable by heating to a temperature above room temperature, when heated will contact the cellulose fibers, and when deactivated will bond at least some of the cellulose fibers together. ### Claim 36 (depends on 35) The article of claim 35, wherein the thermoplastic material is selected from the group consisting of particles or fibers comprising a thermoplastic polymer, cellulose fibers coated with a thermoplastic polymer, and multi-component fibers wherein at least one of the fiber components comprises a thermoplastic polymer. ### Claim 37 (depends on 26) The article of claim 26, wherein said thermoplastic polymer is selected from the group consisting of polyester, polypropylene, and polyethylene. ### Claim 38 (depends on 35) The article of claim 35, wherein the thermosetting material is selected from the group consisting of phenolic resin, polyvinyl acetate, urea formaldehydes, melamine formaldehydes, and acrylics. ### Claim 39 An absorbent article for acquiring, distributing, and storing bodily fluids, the article comprising: an upper acquisition/distribution layer for receiving body fluid from a source, the acquisition/distribution layer including a densified web of cellulose fibers in which at least some of the cellulose fibers are bonded together by a bonding agent comprising a water insoluble, thermoplastic or thermosetting material, said web having been densified after the bonding agent is deactivated and has bound the fibers together, said web having been densified while the bonding agent is deactivated, the densified web having a minimum density equal to or greater than 0.1 g/cc based on the average weight of the fibers and the bonding agent; and a storage layer for receiving body fluid from the acquisition/distribution layer, the storage layer including a densified web of cellulose fibers in which at least some of the cellulose fibers are bonded to each other by a bonding agent, said web having been densified after the bonding agent is deactivated and has bound the fibers together. ### Claim 40 (depends on 39) The article of claim 39, wherein the cellulose fibers in the upper acquisition/distribution layers are selected from the group consisting of non-cross-linked cellulose fibers, cross-linked cellulose fibers, and mixtures thereof. ### Claim 41 (depends on 39) The article of claim 39, wherein said acquisition/distribution layer further comprises a superabsorbent polymer for absorbing liquid components of the body fluids. ### Claim 42 (depends on 39) The article of claim 39, wherein said cellulose fibers in said storage layer are selected from the group consisting of non-cross-linked cellulose fibers, cross-linked cellulose fibers, cellulosic fibers containing a particle binder or densifying/softening agent, and mixtures thereof. ### Claim 43 (depends on 39) The article of claim 39, wherein the cellulose fibers in the storage layer comprise a densified web of fibers in which at least some of the cellulose fibers are bonded to each other by a bonding agent, the web having been densified after the bonding agent is deactivated and has bound the fibers together. ### Claim 44 (depends on 39) The article of claim 39, wherein the fibers in the storage layer further comprise a superabsorbent polymer for absorbing liquid components of the body fluids. ### Claim 45 (depends on 39) The absorbent article of claim 39, further comprising a lower distribution layer including a web of cellulose fibers, said cellulose fibers being selected from the group consisting of non-cross-linked fibers, cross-linked fibers, fibers containing a particle binder, and mixtures thereof. ### Claim 46 (depends on 45) The article of claim 45, wherein the lower distribution layer further comprises a superabsorbent polymer for absorbing liquid components of the body fluids. ### Claim 47 (depends on 39) The article of claim 39, wherein the bonding material comprises a thermoplastic or thermosetting material that is activatable by heating to a temperature above room temperature, when heated will contact the cellulose fibers, and when deactivated will bond at least some of the cellulose fibers together. ### Claim 48 (depends on 47) The article of claim 47, wherein the thermoplastic material is selected from the group consisting of particles or fibers comprising a thermoplastic polymer, cellulose fibers coated with a thermoplastic polymer, and multi-component fibers wherein at least one of the fiber components comprises a thermoplastic polymer. ### Claim 49 (depends on 48) The article of claim 48, wherein said thermoplastic material is selected from the group consisting of polyester, polypropylene, and polyethylene. ### Claim 50 (depends on 48) The article of claim 48, wherein said thermosetting material is selected from the group consisting of phenolic resin, urea formaldehydes, melamine formaldehydes, polyvinyl acetate, or acrylics. ### Claim 51 A method for producing a densified web of cellulose fibers comprising: forming a web of cellulose fibers containing a bonding agent comprising a water insoluble, thermoplastic or thermosetting material; activating the bonding agent so that the bonding agent contacts at least some of the cellulose fibers; thereafter deactivating the bonding agent to bind at least some of said cellulose fibers together; and thereafter densifying said web of cellulose fibers to a density of at least 0.1 g/cc, said web being densified while said bonding agent is deactivated. ### Claim 52 (depends on 51) The method of claim 51, wherein said web is densified to a density between 0.1 g/cc and 0.7 g/cc. ### Claim 53 (depends on 52) The method of claim 52, wherein said web is densified to a density ranging from 0.3 g/cc to about 0.7 g/cc. ### Claim 54 (depends on 51) The method of claim 51, wherein the densified web has a wet pad integrity greater than the wet pad integrity of a non-bonded, densified web of cellulose fibers that has been densified to substantially the same degree. ### Claim 55 (depends on 51) The method of claim 51, wherein the densified web formed by the method has an absorbent capacity that is at least about equivalent to a non-bonded, densified web of cellulose fibers. ### Claim 56 (depends on 51) The method of claim 51, further comprising incorporating a superabsorbent polymer into the web of cellulose fibers before activating the bonding agent. ### Claim 57 (depends on 56) The method of claim 56, wherein the superabsorbent polymer is present in an amount up to about 70% by weight based on the weight of the fiber and the bonding agent. ### Claim 58 (depends on 51) The method of claim 51, wherein the fibers are selected from the group consisting of cross-linked cellulose fibers, non-cross-linked cellulose fibers, cellulosic fibers containing a particle binder, and mixtures thereof. ### Claim 59 (depends on 51) The method of claim 51, wherein the bonding material comprises a thermoplastic or thermosetting material that is activatable by heating to a temperature above room temperature, when heated will contact at least a portion of the cellulose fibers and when deactivated will bond at least some of the cellulose fibers together. ### Claim 60 (depends on 59) The method of claim 59, wherein the thermoplastic material is selected from the group consisting of fibers or particles comprising a thermoplastic polymer, cellulose fibers coated with a thermoplastic polymer, and multi-component fibers wherein at least one of said components comprises a thermoplastic polymer. ### Claim 61 (depends on 59) The method of claim 59, wherein the thermoplastic material is selected from the group consisting of polyester, polyethylene, and polypropylene. ### Claim 62 (depends on 61) The method of claim 61, wherein the thermosetting material is selected from the group consisting of phenolic resin, urea formaldehydes, melamine formaldehydes, polyvinyl acetate, and acrylics. ### Claim 63 (depends on 57, 58, 59, 60, 61, 62) The product produced by the method of claim 57, 58, 59, 60, 61 or 62.