# US 6,296,929 B1 · Absorbent member exhibiting exceptional expansion properties when wetted

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- Number: US 6,296,929 B1
- Document ID: US6296929B1
- Status: Granted
- Kind: B1
- Application number: 09/290,323
- Filed: 1999-04-12
- Granted: 2001-10-02
- Earliest claimed: 1999-04-12
- Assignees: Kimberly-Clark Worldwide, Inc.
- Inventors: Victor Michael Gentile; James Jay Tanner
- Web page: https://patentgrep.com/patent/US6296929B1

## CPC

- A61F 13/47263: {with activating means, e.g. elastic, heat or chemical activatable means}
- A61F 13/531: having a homogeneous composition through the thickness of the pad (A61F13/538, A61F13/539 take precedence)
- A61F 2013/1539: {being expandable}
- Y10T 428/24992: Density or compression of components
- Y10T 442/30: Woven fabric [i.e., woven strand or strip material]
- Y10T 442/60: Nonwoven fabric [i.e., nonwoven strand or fiber material]
- Y10T 442/627: Strand or fiber material is specified as non-linear [e.g., crimped, coiled, etc.]
- 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)
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

An absorbent member is disclosed which has a high absorbent capacity and which exhibits exceptional expansion properties when wetted by an aqueous fluid. The absorbent member includes a multitude of randomly oriented cellulosic fibers having an average length of from between about 1 mm to about 5 mm and containing at least about 20% lignin within each fiber. The absorbent member also has a moisture content of from between about 1% to about 20% water by weight of fiber and has a density in the range of from between about 0.1 g/cc to about 1 g/cc. The fibers are stressed and bonded by hydrogen bonds and are retained in an elastically stressed condition.

## Claims

### Claim 1

An absorbent member exhibiting exceptional expansion properties when wetted, said absorbent member consisting of a multitude of randomly oriented chemi-thermo-mechanical cellulosic fibers having an average length from about 1 mm to 5 mm and containing at least about 20% lignin within said cellulosic fibers, said absorbent member having a moisture content of from between about 1% to about 20% water by weight of fiber, said fibers being compacted and bonded by hydrogen bonds and being retained in a stressed condition, said hydrogen bonds being breakable upon contact with an aqueous fluid thereby allowing rapid expansion of said absorbent member, and said absorbent member having a density of from between about 0.5 g/cc to about 1 g/cc.

### Claim 2 (depends on 1)

The absorbent member of claim 1 wherein said cellulosic fibers have been stressed from a non-stressed condition wherein said cellulosic fibers had a bulk density of from between about 0.01 g/cc to about 0.1 g/cc.

### Claim 3 (depends on 2)

The absorbent member of claim 2 wherein said cellulosic fibers in a stressed condition have a density of from between about 0.5 g/cc to about 0.8 g/cc.

### Claim 4

An absorbent member having a high absorbent capacity and exhibiting exceptional expansion properties when wetted by an aqueous fluid, said absorbent member consisting of a multitude of randomly oriented chemi-thermo-mechanical cellulosic fibers having an average length of from between about 1 mm to 5 mm, said fibers formed from softwood and containing at least about 20% lignin within said fibers, said absorbent member having a moisture content of from between about 1% to about 20% water by weight of fiber and having a density of from between about 0.5 g/cc to about 1 g/cc, and said fibers being compacted and bonded by hydrogen bonds and retained in an elastically stressed condition, said hydrogen bonds being breakable upon contact with an aqueous fluid thereby allowing rapid expansion of said absorbent member.

### Claim 5 (depends on 4)

The absorbent member of claim 4 wherein said moisture content ranges from between about 5% to about 15% water by weight of fiber.

### Claim 6 (depends on 4)

The absorbent member of claim 4 wherein said cellulosic fibers have an average length of from between about 1 to about 3 millimeters.

### Claim 7 (depends on 4)

The absorbent member of claim 4 wherein said cellulosic fibers have an average diameter of from between about 10 to about 40 microns.

### Claim 8 (depends on 4)

The absorbent member of claim 4 wherein said cellulosic fibers have been stressed from a non-stressed condition wherein said cellulosic fibers had a bulk density of from between about 0.01 g/cc to about 0.1 g/cc.

### Claim 9

An absorbent member having a high absorbent capacity and exhibiting exceptional expansion properties when wetted by an aqueous fluid, said absorbent member consisting of a multitude of randomly oriented stiff chemi-thermo-mechanical cellulosic fibers having an average length of from between about 1 mm to about 5 mm, said fibers formed from softwood and containing at least about 20% lignin within said fibers, said absorbent member having a moisture content of from between about 2% to about 15% water by weight of fiber and having a density of from between about 0.5 g/cc to about 0.8 g/cc, and said fibers being compacted and bonded by hydrogen bonds and retained in an elastically stressed condition, said hydrogen bonds being breakable upon contact with an aqueous fluid thereby allowing rapid expansion of said absorbent member.

### Claim 10 (depends on 9)

The absorbent member of claim 9 wherein said chemi-thermo-mechanical fibers are bleached.

### Claim 11 (depends on 9)

The absorbent member of claim 9 wherein at least a portion of said cellulosic fibers have a non-linear configuration.

### Claim 12 (depends on 9)

The absorbent member of claim 9 wherein said fibers, when retained in an elastically stressed condition, exhibit recoverable bending, compression and shear forces.

### Claim 13

An absorbent member having a high absorbent capacity and exhibiting exceptional expansion properties when wetted by an aqueous fluid, said absorbent member consisting of a multitude of randomly oriented chemi-thermo-mechanical cellulosic fibers having an average length of from between about 1 mm to about 5 mm and containing at least about 20% lignin within said cellulosic fibers, said absorbent member having a moisture content of from between about 5% to about 15% water by weight of fiber and having a density of from between about 0.5 g/cc to about 0.8 g/cc, and said fibers being compacted and bonded by hydrogen bonds and retained in an elastically stressed condition, said hydrogen bonds being breakable upon contact with an aqueous fluid thereby allowing rapid expansion of said absorbent member.

### Claim 14 (depends on 13)

The absorbent member of claim 13 wherein said cellulosic fibers have been stressed from a non-stressed condition wherein said cellulosic fibers had a bulk density of from between about 0.01 g/cc to about 0.1 g/cc.

### Claim 15 (depends on 13)

The absorbent member of claim 13 wherein said absorbent member contains a potential energy that can be recovered according to the formula E=−a/b where: “E” is the potential energy that can be recovered from the absorbent member: “a” is the maximum pressure exerted by the triggered absorbent member upon its contact with an aqueous fluid: and “b” is a constant value ranging between −0.015 and −0.045 which is a function of the maximum pressure and maximum volume change of the absorbent member.

### Claim 16 (depends on 13)

The absorbent member of claim 13 wherein said cellulosic fibers have an average length of from between about 1 to about 3 millimeters.

### Claim 17 (depends on 13)

The absorbent member of claim 13 wherein said chemi-thermo-mechanical fibers are softwood fibers.

### Claim 18 (depends on 17)

The absorbent member of claim 17 wherein said softwood fibers are bleached.