NZ198895A

NZ198895A - Sanitary napkin with reservoir formed by compression of the fibrous batt

Info

Publication number: NZ198895A
Application number: NZ198895A
Authority: NZ
Inventors: D C Holtman
Original assignee: Johnson & Johnson Baby Prod
Priority date: 1980-11-17
Filing date: 1981-11-06
Publication date: 1984-02-03
Also published as: ES269737U; GR68172B; ES267714U; GB2087730A; ES267714Y; BR8107160A; ES267716U; PT73994A; ES267715U; AR242710A1; ES269737Y; DE3145398A1; MY8600143A; ES267716Y; ES267715Y; AU7750781A; GB2087730B; AU549282B2; CA1185051A; ZA817932B

Description

198895 Priority DEt■>{&): JX\ U.'$Q .

Comp!ot3 Specification FUed: Publication Date: ... .T • iitiiiii P.O. Jc-jrnc!, fJo: Patents Form No. 5 Number PATENTS ACT 1953 Dated COMPLETE SPECIFICATION ABSORBENT STRUCTURE WITH RESERVOIR X/We JOHNSON & JOHNSON BABY PRODUCTS COMPANY of 501 George Street, New Brunswick, New Jersey, United States of America, a corporation organised under the laws of the state of New Jersey, United States of America do hereby declare the invention for which $£we pray that a Patent may be granted to jne/us, and the method by which it is to be performed, to be particularly described in and by the following statement: - 1 - (followed by page la) J 98895 -la- JBP 191 Background of the Invention Disposable absorbent structures such as disposable diapers, sanitary napkins and incontinence pads have met with 5 increased commercial acceptance in recent years primarily because of their convenience. Many different constructions have been proposed and used and some have met with widespread commercial success in spite of certain inadequacies in functional properties.

One of the most serious prior art problems has been the inability to provide a suitable construction that can accept a large void of body fluids. This is particularly true of the adult incontinent whether the incontinent be 15 active and working or ill and bedridden. Various attempts have been made to provide special structures to absorb a large body fluid void. These include U. S. Patent 3,441,024 to H. J. Ralph, U. S. Patent 3,747,602 to H. J. Ralph, U. S. Patent 3,968,798 to K. C. Hokanson, 20 and U. S. Patent 4,067,366 to R. L. Johnson. While these various constructions were designed to assist the adult incontinent, the problem of providing an overall absorbent structure which will handle a full volume discharge of urine without leakage still remains.

Whether the incontinent be an adult or an infant, disposable structures generally have not accepted and held a full volume discharge of urine without leakage onto clothing. Similarly, the sanitary napkins known in the art will not 30 necessarily hold a full volume discharge of menstrual fluid. The present invention provides an absorbent structure which may be used as an infant diaper, an adult 198895 -2- JBP 191 incontinence device, a sanitary napkin, an incontinence pad, or the like.

Summary of the Invention The present invention provides an absorbent structure to receive and contain body fluids comprising a loosely-compacted, cellulosic fibrous batt having a moisture-impermeable backing sheet on one side and a fabric cover 10 which covers at least the side of the absorbent batt opposite the backing sheet on the other side. The absorbent batt is provided with a reservoir which has a capacity sufficient to hold at least 75% of the body fluid discharged in one second. The reservoir is situated in 15 the void zone and is formed by compression of the cellulosic fibers in that zone.

The absorbent structure may be incorporated in a disposable diaper such as for an infant or in an adult diaper with a 20 larger liquid holding capacity. Furthermore, the absorbent structure may be incorporated in a sanitary napkin as well as in an incontinence pad. In each instance the opening of the reservoir is placed in the void zone allowing immediate acceptance by the reservoir of the body fluid 25 discharge. Generally, the discharge capacity of the reservoir will be at least 10 cc.

The reservoir is created by compression of the loosely-compacted, cellulosic fibers in the reservoir area. The 30 compaction may be carried out by application of pressure in the shape desired for the reservoir. This may be done by a stamping-type operation or by an embossing roll or the like. 198895 -3- JBP 191 Brief Description of the Drawings FIG. 1 is a perspective view of one embodiment of the present invention; FIG. 2 is a cross-sectional view taken along line 2--2 of the embodiment of FIG. 1; FIG. 3 is a top view of another embodiment of the present 10 invention; FIG. 4 is a top view of still another embodiment of the present invention; FIG. 5 is a perspective view of a disposable diaper utilizing the absorbent structure of the present invention; FIG. 6 is a perspective view of a sanitary napkin incorporating the absorbent structure of the present invention; and FIG. 7; is a cross-sectional view taken along line 7--7 of FIG. 6.

Detailed Description of the Invention While this invention is susceptible of embodiment in many different forms, there is shown in the drawings, and herein will be described in detail, preferred embodiments of the invention and modifications thereof. It is understood that 30 the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the embodiments illustrated. The scope of the invention will be pointed out in the appended claims. 198895 -4- JBP 191 Referring to the drawings and particularly to FIG. 1, an absorbent structure 10 is provided with a reservoir 12 lying below the cover 13. The cover is a moisture-permeable non-woven fabric. FIG. 2 shows the absorbent 5 structure of FIG. 1 in cross-sectional view along line 2--2» The moisture-permeable exterior cover 18 completely wraps the absorbent structure. A moisture barrier 16 which is a moisture-impermeable backing sheet, covers the bottom area as well as both sides of the structure. Immediately 10 adjacent the cellulosic batt 22 is a wrap of tissue 14. It may not be necessary to have a tissue wrapping the cellulosic batt but if the cellulosic batt is quite thick, such as an inch or more, it may be desirable to provide a tissue wrap to assist with maintenance of the desired 15 shape of the absorbent structure. The cellulosic fibrous batt 22 is provided with a reservoir 20 and a densified fibrous region 24. the surface of the fibrous batt containing the opening of the reservoir 20 is placed toward the wearer with the opening in the void zone. A 20 release liner 26 is removed to expose adhesive so as to secure the structure to the underwear of the wearer.

FIGS. 3 and 4 are top views of typical cellulosic batts used in the absorbent structure of the invention. The 25 cellulosic batt 30 contains a reservoir 32 having the shape of a rectangle. The reservoir may be located nearer one end of the cellulosic batt 30, e.g., one-third of the way, or between the center and end, to assist in location in the void zone of the wearer. In FIG. 4 a cellulosic 30 batt 40 is provided with a reservoir 42 having an oval shape. Any desired shape and size may be used so long as the reservoir covers at least one square inch of surface and contains at least 10 cc in volume. 198895 -5- JBP 191 Referring now to FIG. 5, a disposable diaper 50 is shown having a moisture-impermeable backing sheet 52. Superimposed upon the backing sheet 52 is a loosely-compacted, cellulosic fibrous batt 54. The fibrous batt contains a 5 reservoir 56 created by compression or compaction of the fibers in that region. The cellulosic batt 54 is covered by a moisture-permeable facing 58 of non-woven fabric.

The facing and the backing are adhered in the margin regions. In addition, glue lines 57 are used to secure 10 the fibrous batt to the backing. Tape tabs 59 are provided to secure the diaper about the wearer.

Referring now to FIGS. 6 and 7, a sanitary napkin 60 is depicted. The cover 62 shown in FIG. 6 is a moisture-15 permeable non-woven fabric. FIG. 7 is a cross-sectional view taken along line 7--7 of FIG. 6. A cellulosic fibrous batt 64 is partially surrounded by a moisture barrier 70. The entire structure is wrapped in the moisture-permeable cover 72. The cellulosic batt 64 20 contains a reservoir 66. At the bottom of the reservoir is a dense fibrous area 68. The dense fibrous area 68 is created when the reservoir 66 is formed.

The loosely-compacted, cellulosic fibrous batt used in 25 the absorbent structure of the present invention is formed from wood pulp fibers, rayon fibers, or cotton linters, or mixtures thereof. The batt is primarily held together by interfiber bonds requiring no added adhesive. In some instances, the batt may contain synthetic fusible fibers, 30 such as polyethylene, polypropylene and the like. The batt is a low bulk density coherent web of loosely-compacted cellulosic fibers preferably comminuted wood pulp fibers in the form of so-called "fluff." 198895 -6- JBP 191 The reservoir in the cellulosic batt is created by compressing the portion of the batt which it is desired become a reservoir. The compression should be sufficient to create a reservoir of sufficient depth to hold at 5 least 10 cc. The base of the reservoir is a densified fibrous region wherein the fibers are compacted. The densified region quickly absorbs the body fluid and commences distribution of the fluid to other parts of the cellulosic batt. In addition, it may be desirable 10 to provide a paper-like densified layer on the side of the batt opposite the reservoir. The paper-like densified layer is formed by a slight moistening of the surface of the batt followed by light compaction using the application of pressure. U. S. Patent 3,017,304, 15 Burgeni, provides such a densified layer in a loosely-compacted, cellulosic fibrous batt.

The cover provided on the absorbent structure of the present invention is a non-woven fabric having a high 20 degree of moisture permeability. For example, the fabric may be polyester, polyethylene, polypropylene, nylon, rayon, or the like. Preferably, the fabric used for the cover is a lightweight fabric in the range of 0.3 to 5.0 oz. per square yard and with a density less than 25 0.2 gms/cc. The most suitable fabrics have unusually high elongation, loft, softness and drape characteristics. Though the cover is moisture-permeable, it is preferably of the type which after permeation of the moisture, prevents strike-back of the body fluid when the absorbent 30 structure is approaching saturation. 198895 -7- JBP 191 The body of the cellulosic fibrous batt is substantially more wettable than the cover and tends to draw liquid away from the facing layer. Thus the void occurs and the cover is permeated and the liquid deposited in the reservoir. The individual fibers of the batt are extremely wettable and thus draw the liquid into the fibrous batt. The base of the reservoir is a densified fibrous region wherein the capillary radius is quite, small. Thus the capillary pressure is increased and the liquid is rapidly distributed to portions of the cellulosic batt. The densified fibrous region at the base of the reservoir provides the maximum capillary pressure because it combines the very low contact angle of the fibers of the batt with the high density of the densified fibers.

The individual fibers of the batt are extremely wettable, generally having liquid-fiber contact angles below about 15° and approaching zero in the optimum embodiment. The wickability or preferential absorptivity of the body of the batt for water is limited, however, by its low density which results in large effective capillary radius for the capillaries between adjacent fibers.

The pressure causing a liquid to enter a cylindrical capillary is.expressed by the equation 2 v cos 9 p = - wherein P is the capillary pressure, V is the surface tension of the liquid, 9 is the liquid-fiber contact angle, and r is the capillary radius. 198895 -8- JBP 191 With a given liquid, the pressure (capillary force) increases with the cosine of the liquid-fiber contact angle (reaching a maximum where the angle is zero) and increases with narrower capillary radii so that narrower capillaries will draw liquid from wider ones.

The relative wickability between the cover layer and the body of the fibrous batt is affected by both the relative densities of the layers and the relative wettability of the individual fibers in each layer. The individual fibers of the batt have substantially smaller liquid-fiber contact angles than those of the cover layer overcoming the density difference and providing a substantial overall increase in capillary pressure to absorb liquid into the body of the batt.

A densified fiber layer such as that at the base of the reservoir provides the maximum capillary pressure because it combines the very low contact angle of the fibers of the batt with the high density (small capillary radius) of the densified fibers.

Thus when urine is voided into an area in the cover layer, it partially t^ets a small portion of the cover layer and is passed through the cover layer, almost instantaneously, to the reservoir. It then comes into contact with the body of the batt surrounding the reservoir and is preferentially absorbed into the body of the batt because of the enhanced wettability of the reservoir and particularly the base of the reservoir. The same is true when the body fluid is a menstrual fluid or other liquid exudate. 198895 -9- JBP 191 It will be understood by those skilled in the art that variations and modifications of the specific embodiments described above may be employed without departing from the spirit and scope of the invention as defined in the 5 appended claims. 'i o q o o r I / O U /

Claims

WHAT WE CLAIM IS: ~xv~ oor xsx

1. An absorbent structure suitable for absorption of body fluids comprising a moisture-impermeable backing sheet; an absorbent, loosely-compacted, cellulosic fibrous batt, 5 superimposed on said backing sheet; and a moisture- permeable fabric cover, covering at least the side of said absorbent batt opposite said backing sheet, said absorbent batt being provided with a reservoir having a capacity sufficient to hold at least 75% of the body fluid 10 discharged in one second, said reservoir being situated nearer one end of the batt than the other and being formed by compression of the cellulosic- fibrous' batt.

2. The absorbent structure of Claim 1 wherein the 15 reservoir is created by a depression in the fibrous batt and has a capacity of at least 10 cc.

3. The absorbent structure of Claim 1 wherein the base / of the reservoir is a densified region of the fibers of 20 the fibrous batt.

4. The absorbent structure of Claim 1 wherein the reservoir is located between the center and one transverse end of the absorbent structure. 25

5. The absorbent structure of Claim 1 wherein the capacity of the reservoir is sufficient to hold at least 90% of the body fluid discharged in one second. >■1 v i ■ # •J- . ; L. -11- i Opp Q r,

6. An adult incontinence device substantially rectangular in shape comprising a moisture-impermeable backing sheet; an absorbent, loosely-compacted cellulosic fibrous batt superimposed on said backing sheet; and a moisture-permeable fabric cover, covering at least the side of said absorbent batt opposite said backing sheet, said absorbent batt being provided with a reservoir covering at least one square inch of the surface of the batt and having a capacity of at least 10 cc and sufficient to hold at least 75% of the body fluid discharged in one second, said reservoir being situated nearer one end of the bath than the other and being formed by compression of the cellulosic fibrous batt.

7. The adult incontinence device of Claim 6 wherein said backing sheet is provided with an adhesive strip for securement of the device when worn.

8. A disposable diaper comprising a moisture-impermeable backing sheet; an absorbent, loosely-compacted, cellulosic fibrous batt, superimposed on said backing sheet; and a moisture-permeable facing superimposed on the side of the fibrous batt opposite said backing sheet, said absorbent batt being provided with a reservoir having a capacity sufficient to hold at least 75% of the body fluid discharged in one second, said reservoir being situated nearer one end of the batt than the other and being formed by compression of the cellulosic fibrous batt.

9. The disposable diaper of Claim 8 wherein the reservoir has as its base a densified fibrous region and has a capacity of at least 10 cc. v^: \ -12-

10. A sanitary napkin comprising a moisture-permeable outer layer containing a moisture-impermeable backing sheet, an absorbent loosely-compacted cellulosic fibrous batt, said absorbent batt being provided with a reservoir having a capacity sufficient to hold at least 75% of the body fluid discharged in one second, said reservoir being situated nearer one end of the batt than the other and being formed by compression of the cellulosic fibrous batt.

11. The sanitary napkin of Claim 10 wherein the base of the reservoir is a densified region of the fibers of the fibrous batt. WEST-WALKER, McCABE per: ATTORNEYS FOR THE APPLICANT