US5137537A
Expired / Lapsed
US
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Absorbent structure containing individualized, polycarboxylic acid crosslinked wood pulp cellulose fibers
Assignee: Procter and Gamble Cellulose Co
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Filing: 1990-10-17
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Granted: 1992-08-11
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Expires: 2010-10-17
Abstract
Abstract Disclosed are absorbent structures containing individualized, crosslinked fibers. The individualized, crosslinked fibers preferably have a C2-C9 polycarboxylic acid crosslinking agent reacted with the fibers in the form of intrafiber crosslink bonds. Preferably, the crosslinking agent is citric acid, and between about 0.5 mole % and about 10.0 mole % crosslinking agent react to form the intrafiber crosslink bonds. Also preferably, the absorbent structures have actual dry densities greater than their corresponding equilibrium wet densities, and expand upon wetting. The absorbent structures may also contain hydrogel-forming material.
Inventors
- 👤 Carlisle M. Herron
- 👤 David J. Cooper
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 04:23
CPC Classifications
D; D21; D21C; D21C9/00; D21C9/001; D21C9/002; D21C9/005; A; A61; A61L; A61L15/00; A61L15/16; A61L15/22; A61L15/28; D04; D04H; D04H1/00; D04H1/40; D04H1/58; D04H1/587; D04H1/64; D06; D06M; D06M13/00; D06M13/10; D06M13/184; D06M13/192
Claims Analysis
Total Claims: 28
Claim 1
Independent Claim
163 words
An absorbent structure comprising individualized, crosslinked wood pulp cellulosic fibers having between about 0.5 mole % and about 10.0 mole % of a C 2 -C 9 polycarboxylic acid crosslinking agent, calculated on a cellulose anhydroglucose molar basis, reacted with said fibers in an intrafiber ester crosslink bond form, wherein said crosslinked fibers have a water retention value of from about 25 to about 60, and wherein said C 2 -C 9 polycarboxylic acid crosslinking agent is selected from the group consisting of: (i) aliphatic and alicyclic C 2 -C 9 polycarboxylic acids having at least three carboxyl groups per molecule; and (ii) aliphatic and alicyclic C 2 -C 9 polycarboxylic acids having two carboxyl groups per molecule and having a carbon-carbon double bond located alpha, beta to one or both of the carboxyl groups, wherein one carboxyl group in said C 2 -C 9 polycarboxylic acid crosslinking agent is separated from a second carboxyl group by either two or three carbon atoms.
Claim 2
Dependent Claim
163 words
An absorbent structure comprising individualized, crosslinked wood pulp cellulosic fibers having between about 0.5 mole % and about 10.0 mole % of a C 2 -C 9 polycarboxylic acid crosslinking agent, calculated on a cellulose anhydroglucose molar basis, reacted with said fibers in an intrafiber ester crosslink bond form, wherein said crosslinked fibers have a water retention value of from about 25 to about 60, and wherein said C 2 -C 9 polycarboxylic acid crosslinking agent is selected from the group consisting of: (i) aliphatic and alicyclic C 2 -C 9 polycarboxylic acids having at least three carboxyl groups per molecule; and (ii) aliphatic and alicyclic C 2 -C 9 polycarboxylic acids having two carboxyl groups per molecule and having a carbon-carbon double bond located alpha, beta to one or both of the carboxyl groups, wherein one carboxyl group in said C 2 -C 9 polycarboxylic acid crosslinking agent is separated from a second carboxyl group by either two or three carbon atoms.
Claim 3
Dependent Claim
39 words
The absorbent structure of claim 1 wherein said fibers have between about 1.5 mole % and about 6.0 mole % crosslinking agent, calculated on a cellulose anhydroglucose molar basis, reacted therewith in the form of intrafiber ester crosslink bonds.
Claim 4
Dependent Claim
33 words
The absorbent structure of claim 1 wherein said crosslinking agent is selected from the group consisting of citric acid, 1, 2, 3, 4 butane tetracarboxylic acid, and 1, 2, 3 propane tricarboxylic acid.
Claim 5
Dependent Claim
13 words
The absorbent structure of claim 3 wherein said crosslinking agent is citric acid.
Claim 6
Dependent Claim
28 words
The absorbent structure of claim 2 wherein said crosslinking agent is selected from the group consisting of citric acid, 1,2,3,4 butane tetracarboxylic acid, and 1,2,3 propane tricarboxylic acid.
Claim 7
Dependent Claim
13 words
The absorbent structure of claim 5 wherein said crosslinking agent is citric acid.
Claim 8
Dependent Claim
18 words
The absorbent structure of claim 6 wherein said water retention value is between about 28 and about 50.
Claim 9
Dependent Claim
35 words
The absorbent structure of claim 1 wherein said crosslinking agent is selected from the group consisting of oxydisuccinic acid, tartrate monosuccinic acid having the formula ##STR3## and tartrate disuccinic acid having the formula ##STR4## .
Claim 10
Dependent Claim
13 words
The absorbent structure of claim 8 wherein said crosslinking agent is oxydisuccinic acid.
Claim 11
Dependent Claim
38 words
The absorbent structure of claim 8 wherein said fibers have between about 1.5 mole % and about 6.0 mole % crosslinking agent, calculated on a cellulose anhydroglucose molar basis, reacted therewith in the form of intrafiber crosslink bonds.
Claim 12
Dependent Claim
18 words
The absorbent structure of claim 10 wherein said water retention value is between about 28 and about 50.
Claim 13
Dependent Claim
36 words
The absorbent structure of claim 1, 4, 7, or 8, having a dry density and an equilibrium wet density calculated on a dry fiber weight basis, said dry density being greater than said equilibrium wet density.
Claim 14
Dependent Claim
23 words
The absorbent structure of claim 1, 4 or 8 wherein said absorbent structure has a dry density of less than about 0.60 g/cc.
Claim 15
Dependent Claim
26 words
The absorbent structure of claim 1, 4 or 8 wherein said absorbent structure has a dry density of between about 0.05 g/cc and about 0.15 g/cc.
Claim 16
Dependent Claim
44 words
The absorbent structure of claim 7 wherein said absorbent structure has a dry fiber density of between about 0.12 g/cc and about 0.60 g/cc and an equilibrium wet density, calculated on a dry fiber basis, which is less than said actual dry fiber density.
Claim 17
Dependent Claim
44 words
The absorbent structure of claim 11 wherein said absorbent structure has a dry fiber density of between about 0.12 g/cc and about 0.60 g/cc and an equilibrium wet density, calculated on a dry fiber basis, which is less than said actual dry fiber density.
Claim 18
Dependent Claim
29 words
The absorbent structure of claim 1 wherein said structure comprises between about 70% and about 95% individualized crosslinked fibers, and between about 30% and about 5% uncrosslinked cellulosic fibers.
Claim 19
Dependent Claim
15 words
The absorbent structure of claim 1 further comprising a hydrogel-forming material disposed upon said fibers.
Claim 20
Dependent Claim
16 words
The absorbent structure of claim 1 further comprising a hydrogel-forming material disposed within said absorbent structure.
Claim 21
Dependent Claim
22 words
The absorbent structure of claim 19 wherein said hydrogel-forming material is substantially homogeneously blended throughout at least part of said absorbent structure.
Claim 22
Dependent Claim
22 words
The absorbent structure of claim 19 wherein said hydrogel-form material is disposed upon a sheet, said sheet being placed against said fibers.
Claim 23
Dependent Claim
16 words
The absorbent structure of claim 17 further comprising a hydrogen-forming material disposed within said absorbent structure.
Claim 24
Dependent Claim
35 words
A disposable absorbent article comprising a topsheet, a backsheet connected to said topsheet, and an absorbent structure as recited in claim 1, 15, 16, 18, 19, or 22, disposed between said topsheet and said backsheet.
Claim 25
Dependent Claim
32 words
The absorbent structure of claim 1 wherein said absorbent structure has a basis weight of less than about 800 g/m 2 , and a dry density of less than about 0.60 g/cc.
Claim 26
Dependent Claim
32 words
The absorbent structure of claim 19 having a dry density and an equilibrium wet density, calculated on a dry fiber weight basis, said dry density being greater than said equilibrium wet density.
Claim 27
Dependent Claim
23 words
The absorbent structure of claim 25 wherein said absorbent structure has a dry density of between about 0.12 g/cc and about 0.60 g/cc.
Claim 28
Dependent Claim
51 words
The absorbent structure of claim 26 wherein said fibers have between about 1.5 mole % and about 6.0 mole % crosslinking agent, calculated on a cellulose anhydroglucose molar basis, the water retention value of said fibers is from about 28 to about 50, and wherein said crosslinking agent is citric acid.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1995-08-11 | 1996-02-10 | 1996-08-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-08-11 | 2000-02-10 | 2000-08-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-08-11 | 2004-02-10 | 2004-08-11 | $7700.00 | Window Closed / Lapsed |