WO1999060975A1

WO1999060975A1 - Disposable absorbent articles with bm containment

Info

Publication number: WO1999060975A1
Application number: PCT/US1999/012017
Authority: WO
Inventors: Jeffrey Michael Willis; Richard Swee-Chye Yeo
Original assignee: Kimberly-Clark Worldwide, Inc.
Priority date: 1998-05-29
Filing date: 1999-05-28
Publication date: 1999-12-02
Also published as: AU4102299A

Abstract

There is provided a BM containment system for personal care products comprising beams capable of substantially retaining their original dimensions when subjected to a pressure of about 2 psi, while providing a void volume of at least 60 cc. The BM containment system has a low compressibility material in the BM target area, which maintains a compartment(s) in which BM may be contained. If used in a diaper, this BM containment system will function even during the normal activites of a typical baby. The provision of void volume by the containment system also acts to provide liquid isolation from urine by avoiding the forced migration of BM to other parts of the diaper. Such a BM containment system may be used in personal care products like diapers, training pants, absorbent underpants, adult incontinence products, and the like.

Description

DISPOSABLE ABSORBENT ARTICLES WITH BM CONTAINMENT

FIELD OF THE INVENTION

The present invention relates to the field of incontinence management, specifically BM incontinence, and the associated personal care products such as diapers, training pants, adult incontinence products and the like.

BACKGROUND OF THE INVENTION

Personal care products have evolved considerably in the area of preventing urine leakage, but little has been done to address the concern of BM (feces) leakage which is often a much more inconvenient problem than urine leakage. Both urine and BM leakage have been addressed with features such as leg cuffs which appear to reduce leg BM leakage somewhat. If sufficient void volume does not exist to contain the BM within the product, however, this fluid will escape out the back or front of the product, or even over the side of the leg cuff and out the leg opening. Even the best leg cuff design cannot contain BM where there is insufficient void volume in the product to contain it. Hence, one problem that remains is that of providing the necessary void volume inside a personal care product to contain the BM.

Another need related to the issue of BM containment is the need to keep the personal care product volume very low prior to use. Modern packaging techniques significantly compress the products, e.g. diapers, so that transportation costs, shelf space, storage space required of the consumer, etc., are minimized. A successful BM containment device or system must keep the pre-use volume of personal care products low. Further, it is well known that BM contacting the skin is a major factor influencing diaper rash due to enzymatic irritants in the BM. This detrimental effect is made more severe when these irritants interact with urine. Minimizing contact of BM with the skin, and minimizing intermixing of the BM with urine are two skin-health benefits a BM containment system should address and are objects of this invention.

It is an object of this invention, therefore, to provide a BM (feces) containment system for personal care products which keeps the product pre-use volume low. It is a further object of this invention to provide sufficient void volume within the product in which to contain BM in order to reduce the possibility of BM leakage outside the product. It is a further object of this invention to minimize contact of BM with the skin, as well as minimize intermixing of the BM with the urine.

SUMMARY OF THE INVENTION

The objects of this invention are achieved by a BM containment system for personal care products having a low compressibility material in the BM target area, which maintains one or more compartments in which BM may be contained. If used in a diaper, this BM containment system will function even during the normal activities of a typical baby. The provision of void volume by the containment system also acts to provide liquid isolation from urine by avoiding the forced migration of BM to other parts of the diaper. The low compressibility material is in the shape of beams which are capable of substantially retaining their original dimensions when subjected to a pressure of about 2 psi, while the BM containment system provides a void volume of at least 60 cubic centimeters (cc).

BRIEF DESCRIPTION OF THE DRAWINGS

Note that Figures 1-5 have an "a" and "b" view wherein the "a" view is normal to the system and the "b" view is at an angle to show the sides of the system in more detail

Figure 1 shows the simplest configuration of the BM containment system of this invention whereby beams (1) form a box which provides void volume. Note that the layers of fabric comprising each beam are perpendicular to the layers of fabric forming the beam next to it.

Figure 2 shows the configuration of Figure 1 wherein the fabric layers in all of the beams are parallel. Figure 3 shows another configuration wherein the beams approximate a capital "H" with another vertical member in the center.

Figure 4 shows a BM containment system wherein the outer beams are curved.

Figure 5 shows a BM containment system similar to Figures 1 and 2 but with the addition of two vertical beams within the box. Figure 6 graphically illustrates the change in thickness versus load for a number of beams of different materials and methods of construction. DEFINITIONS

"Hydrophilic" describes fibers or the surfaces of fibers which are wetted by the aqueous liquids in contact with the fibers. The degree of wetting of the materials can, in turn, be described in terms of the contact angles and the surface tensions of the liquids and materials involved. Equipment and techniques suitable for measuring the wettability of particular fiber materials or blends of fiber materials can be provided by a Cahn SFA-222 Surface Force Analyzer System, or a substantially equivalent system. When measured with this system, fibers having contact angles less than 90° are designated "wettable" or "hydrophilic", while fibers having contact angles equal to or greater than 90° are designated "nonwettable" or "hydrophobic".

"Layer" when used in the singular can have the dual meaning of a single element or a plurality of elements.

"Liquid" means a nongaseous, nonparticulate substance and/or material that flows and can assume the interior shape of a container into which it is poured or placed.

As used herein the term "nonwoven fabric or web" means a web having a structure of individual fibers or threads which are interlaid, but not in an identifiable manner as in a knitted fabric. Nonwoven fabrics or webs have been formed from many processes such as for example, meltblowing processes, spunbonding processes, and bonded carded web processes. The basis weight of nonwoven fabrics is usually expressed in ounces of material per square yard (osy) or grams per square meter (gsm) and the fiber diameters useful are usually expressed in microns. (Note that to convert from osy to gsm, multiply osy by 33.91 ).

As used herein the term "microfibers" means small diameter fibers having an average diameter not greater than about 75 microns, for example, having an average diameter of from about 0.5 microns to about 50 microns, or more particularly, microfibers may have an average diameter of from about 2 microns to about 40 microns. Another frequently used expression of fiber diameter is denier, which is defined as grams per 9000 meters of a fiber and may be calculated as fiber diameter in microns squared, multiplied by the density in grams/cc, multiplied by 0.00707. A lower denier indicates a finer fiber and a higher denier indicates a thicker or heavier fiber. For example, the diameter of a polypropylene fiber given as 15 microns may be converted to denier by squaring, multiplying the result by .89 g/cc and multiplying by .00707. Thus, a 15 micron polypropylene fiber has a denier of about 1.42 (15² x 0.89 x .00707 = 1.415). Outside the United States the unit of measurement is more commonly the "tex", which is defined as the grams per kilometer of fiber. Tex may be calculated as denier/9.

"Spunbonded fibers" refers to small diameter fibers which are formed by extruding molten thermoplastic material as filaments from a plurality of fine, usually circular capillaries of a spinneret with the diameter of the extruded filaments then being rapidly reduced as by, for example, in US Patent 4,340,563 to Appel et al., and US Patent 3,692,618 to Dorschner et al., US Patent 3,802,817 to Matsuki et al., US Patents 3,338,992 and 3,341 ,394 to Kinney, US Patent 3,502,763 to Hartman, and US Patent 3,542,615 to Dobo et al. Spunbond fibers are generally not tacky when they are deposited onto a collecting surface. Spunbond fibers are generally continuous and have average diameters (from a sample of at least 10) larger than 7 microns, more particularly, between about 10 and 20 microns. "Meltblown fibers" means fibers formed by extruding a molten thermoplastic material through a plurality of fine, usually circular, die capillaries as molten threads or filaments into converging high velocity, usually hot, gas (e.g. air) streams which attenuate the filaments of molten thermoplastic material to reduce their diameter, which may be to microfiber diameter. Thereafter, the meltblown fibers are carried by the high velocity gas stream and are deposited on a collecting surface to form a web of randomly dispersed meltblown fibers. Such a process is disclosed, for example, in US Patent 3,849,241. Meltblown fibers are microfibers which may be continuous or discontinuous, are generally smaller than 10 microns in average diameter, and are generally tacky when deposited onto a collecting surface. As used herein, the term "coform" means a process in which at least one meltblown diehead is arranged near a chute through which other materials are added to the web while it is forming. Such other materials may be wood pulp, superabsorbent particles, cellulose or staple fibers, for example. Coform processes are shown in commonly assigned US Patents 4,818,464 to Lau and 4,100,324 to Anderson et al. Webs produced by the coform process are generally referred to as coform materials.

"Conjugate fibers" refers to fibers which have been formed from at least two polymer sources extruded from separate extruders but spun together to form one fiber. Conjugate fibers are also sometimes referred to as multicomponent or bicomponent fibers. The polymers are usually different from each other though conjugate fibers may be monocomponent fibers. The polymers are arranged in substantially constantly positioned distinct zones across the cross-section of the conjugate fibers and extend continuously along the length of the conjugate fibers. The configuration of such a conjugate fiber may be, for example, a sheath/core arrangement wherein one polymer is surrounded by another or may be a side by side arrangement, a pie arrangement or an "islands-in-the-sea" arrangement. Conjugate fibers are taught, for example, in US Patent 5,382,400 to Pike et al. For two component fibers, the polymers may be present in ratios of 75/25, 50/50, 25/75 or any other desired ratios. The fibers may also have shapes such as those described in US Patents 5,277,976 to Hogle et al. which describes fibers with unconventional shapes. "Biconstituent fibers" refers to fibers which have been formed from at least two polymers extruded from the same extruder as a blend. The term "blend" is defined below. Biconstituent fibers do not have the various polymer components arranged in relatively constantly positioned distinct zones across the cross-sectional area of the fiber and the various polymers are usually not continuous along the entire length of the fiber, instead usually forming fibrils or protofibrils which start and end at random. Biconstituent fibers are sometimes also referred to as multiconstituent fibers. Fibers of this general type are discussed in, for example, US Patent 5,108,827 to Gessner.

"Bonded carded web" refers to webs that are made from staple fibers which are sent through a combing or carding unit, which breaks apart and aligns the staple fibers in the machine direction to form a generally machine direction-oriented fibrous nonwoven web. Such fibers are usually purchased in bales which are placed in a picker which separates the fibers prior to the carding unit. Once the web is formed, it then is bonded by one or more of several known bonding methods. One such bonding method is powder bonding, wherein a powdered adhesive is distributed through the web and then activated, usually by heating the web and adhesive with hot air. Another suitable bonding method is pattern bonding, wherein heated calender rolls or ultrasonic bonding equipment are used to bond the fibers together, usually in a localized bond pattern, though the web can be bonded across its entire surface if so desired. Another suitable and well-known bonding method, particularly when using bicomponent staple fibers, is through-air bonding.

"Airlaying" is a well known process by which a fibrous nonwoven layer can be formed. In the airlaying process, bundles of small fibers having typical lengths ranging from about 6 to about 19 millimeters (mm) are separated and entrained in an air supply and then deposited onto a forming screen, usually with the assistance of a vacuum supply. The randomly deposited fibers then are bonded to one another using, for example, hot air or a spray adhesive. As used herein "uncreped through-air dried" or "UCTAD" refers to a process of making a material, and to the material made thereby, by forming a furnish, often of cellulosic fibers, depositing the furnish on a traveling foraminous belt, subjecting the fibrous web to non-compressive drying to remove the water from the fibrous web, and removing the dried fibrous web from the traveling foraminous belt without using traditional creping techniques. Such webs are described in US Patents 5,048,589, 5,348,620 and 5,399,412.

As used herein "thermal point bonding" involves passing a fabric or web of fibers to be bonded between a heated calender roll and an anvil roll. The calender roll is usually, though not always, patterned in some way so that the entire fabric is not bonded across its entire surface, and the anvil roll is usually flat. As a result, various patterns for calender rolls have been developed for functional as well as aesthetic reasons. Typically, the percent bonding area varies from around 10% to around 30% of the area of the fabric laminate web. As is well known in the art, the spot bonding holds the laminate layers together as well as imparts integrity to each individual layer by bonding filaments and/or fibers within each layer.

As used herein, "through-air bonding" means a process of bonding a fiber web in which air sufficiently hot to melt the polymers of which the fibers of the web are made is forced through the web. The air velocity is frequently between 100 and 500 feet per minute and the dwell time may be as long as 6 seconds. The melting and resolidification of the polymer provides the bonding.

"Personal care product" means diapers, training pants, absorbent underpants, feminine hygiene products and adult incontinence products. TEST METHODS

Permeability: Permeability (k) may be calculated from the Kozeny-Carman equation. This is a widely used method. References include an article by R.W. Hoyland and R. Field in the journal Paper Technology and Industry. December 1976. p. 291-299 and Porous Media Fluid Transport and Pore Structure by F.A.L. Dullien, 1979, Academic Press, Inc. ISBN 0-12-223650-5.

Calculated

Variable Equation Dimensions

Permeability = k = ε³ 1 Darcys

KS₀ ²(1 - ε)² 9.87 x 10⁹

Kozeny Constant = K 3.5ε³ r dimensionless

1 + 57(1 - ε) d-ε)^{05 L} ']

Surface area per = S_v cm²/g

= Σ ^X' mass of the ' ^r,,eff P, material

Mass weighted = Pavg f ^"' - X. I g/cm³ average ^Σ π ' component density

Surface area per = So ⁼ S_v Pavg cm^"1 solid volume of the material

Porosity = Pweb dimensionless

⁼ ι-∑^χ,

P.

Effective fiber = ■ i.ef _ V, cm radius SA,

Density of web = Pweb BW g/cm³ 10³ -t

for long cylinders

for spheres

where d, = diameter of component i (microns)

P, = density of component i (g/cm³)

x, = mass fraction of component i in web

BW = weight of sample/area (g/m²) t = thickness of sample (mm) under 0.05 psi

(23.9dyne/cm²) or 2.39 Pascal (N/m²) load

Permeability Example Calculation

For a structure which contains 57% southern softwood pulp, 40% superabsorbent and 3% binder fiber, and has a basis weight of 617.58 g/m² and a bulk thickness of 5.97 mm at 0.05 psi the example permeability calculation follows. The component properties are as follows (note shape is approximated):

Component Shape Diameter d, Densitv p. Mass

(microns) (g/cm³) Fraction x,

Southern softwood Cylinder 13.3 1.55 0.57

Superabsorbent Sphere 1125 1.50 0.40

Binder Cylinder 17.5 0.925 0.03

p_web (g/cm³) _ BW ι o³ - t

Pwe (g/cm³) _ 617.58 (5.97) 10³

Pwe_b (g/cm³) = 0.1034 ε _

= ι - Σ P ,

0.1034 0.1034 0.1034

= 1 - 0.57 - 0.40 — - 0.03-

1.55 1.49 0.925 ε = 0.9309 S_v (cm²/g) _{= ∑} x,

' ^r,,eff P,

S_v (cm²/g) =

0.57 0.40 0.03

13.3 ) 1125 17.5

1.55 1.49 x 0.925

4x 10V V6x 10V W x 1(T

S_v (cm²/g) = 1194 Pav_g (g/cm³)

= ∑-^*- P

Pavg (g/cm³) _ ( 0.57 0.40 0.03

1.55 1.49 0.925

Pav_g (g/cm³) = 1.496

So (cm^-1) = S_v p_avg

S₀ (cm^"1) =1194x1.496

So (cm^'1) =1786

K _ 3.5(0.9309)³

[l + 57(1 - 0.9309)³]

(1- 0.9309)⁰⁵

K = 10.94 k ε³

KS₀ ²(l-ε)² 9.87 x 10^"

(0.9309)³

(10.94)(1786)²(1 - 0.9309)² 9.87 x 10^"9 k =491 darcys Material caliper (thickness): The caliper of a material is a measure of thickness and is measured at 0.05 psi with a Starret-type bulk tester, in units of millimeters.

Density: The density of the materials is calculated by dividing the weight per unit area of a sample in grams per square meter (gsm) by the bulk of the sample in millimeters (mm) at 68.9 Pascals and multiplying the result by 0.001 to convert the value to grams per cubic centimeter (g/cc). A total of three samples would be evaluated and averaged for the density values.

Wicking Time and Vertical Liquid Flux of an Absorbent Structure (Capillary Tension): A sample strip of material approximately 2 inches (5 cm) by 15 inches (38 cm) is placed vertically such that when the sample strip is positioned above a liquid reservoir at the beginning of the test, the bottom of the sample strip will just touch the liquid surface. The liquid used was a 8.5 g/l saline solution. The relative humidity should be maintained at about 90 to about 98 percent during the evaluation. The sample strip is placed above the known weight and volume of liquid and a stopwatch started as soon as the bottom edge of the sample strip touches the surface of the solution.

The vertical distance of the liquid front traveling up the sample strip and the liquid weight absorbed by the sample strip at various times is recorded. The time versus liquid front height is plotted to determine the Wicking Time at about 5 centimeters and at about 15 centimeters. The weight of the liquid absorbed by the sample strip from the beginning of the evaluation to about 5 centimeters and to about 15 centimeters height is also determined from the data. The Vertical Liquid Flux value of the sample strip at a particular height was calculated by dividing the grams of liquid absorbed by the sample strip by each of: the basis weight (gsm), of the sample strip; the time, in minutes, needed by the liquid to reach the particular height; and the width, in inches, of the sample strip. Capillary tension in materials not containing superabsorbents (e.g. surge materials) is measured simply by the equilibrium vertical wicking height of a 8.5 g/l saline solution after 30 minutes.

Compression test: The compression test measures the resistance to compression of a material. This relatively simple test uses a Compressometer from the Frazier Precision Instrument Co., Inc., 210 Oakmont Avenue, Gaithersburg, MD 20760 and is performed generally according to the US Department of Commerce, Bureau of Standards Research Paper RP561 published in the Bureau of Standards Journal of Research, Vol. 10, June 1933, p. 705-713. The Compressometer has a foot of three inches (76 mm) in diameter under which the sample is placed. After being properly calibrated and parallelism between the foot and base ensured, force may be applied to the sample vertically by the Compressometer and may be monitored by a dial or other indicator means. After the desired amount of force has been applied to the sample, it is removed from the device and its thickness measured and compared to its starting thickness. The results may be displayed graphically as in Figure 6, for example.

DETAILED DESCRIPTION

The present invention provides a new component in a personal care product like a diaper or similar incontinent product which provides void volume for the holding of BM. This BM compartment resides adjacent to the anal opening and serves to take in BM and contain it. The BM compartment, due to its function of collecting and containing the BM, serves to minimize skin contact with the BM by preventing the spread of BM outside the BM compartment. Leakage is minimized by (1 ) providing void volume to contain the BM inside the diaper or similar product, and (2) containing the BM within the BM compartment's perimeter, which lies inside the product.

Through empirical testing, it has been found that the average baby exerts up to about 2 psi of pressure on a diaper in the normal sitting position. This can, of course, be increased by falling or abruptly sitting from the standing position, but is a useful pressure for developmental purposes. By the same methods, it has been found that 95 percent of BM events for babies are less than 60 cc in volume with an average of about 30 cc. A successful BM containment system, therefore, must provide at least this amount of volume and maintain it under pressures of at least about 2 psi.

Materials which will meet the requirements of the BM containment system include nonwoven fabrics and foams. A suitable material may be made, for example, from nonwoven fabrics by using strips of nonwoven fabric which are about 0.5 to 1 inch (1.25 to 2.5 cm) in width, and bonding the strips to each other lengthwise so that a long, thick "beam" of fabric is produced. In this configuration, the beam is placed such that the ends of the fibers pointing towards and away from the wearer, i.e., the Z-direction. Such an oriented fiber configuration provides greater resistance to collapsing in the Z-direction than the configuration in which the fibers are laying on their sides, i.e., parallel to the skin of the wearer.

The polymer from which the fibers are made also plays a part in increasing the strength of the fibers and the beam. The fibers may be made from nylons, known for their strength, polyesters and polyolefins. Polyolefins, because of their low cost and availability, are common polymers for the production of nonwoven fibers and fabrics. Most common are polypropylene and polyethylene.

The configuration of individual fibers also plays a role in the strength of the beam. It has been found, for example, that conjugate fibers can be designed to deliver greater strength at the same basis weight and fiber size, than homopolymer fibers of the same or similar polymers. Other multiple polymer fibers include biconstituent fibers in which a fiber is made from a polymer blend. A particularly suitable fiber is a side-by-side conjugate fiber of polypropylene and polyethylene which may be crimped. If crimped, however, it is preferable that the crimping is at a low rate; greater crimp resulting in loss of Z-direction compression resistance. Bonding of the laminate for the containment beams of this invention may be accomplished by any satisfactory method known in the art. Such methods include thermal and adhesive bonding.

Various designs for placement of BM containment beams in a personal care product have been developed. The beams may, for example, be placed in a configuration resembling the letters "H" or "N" or may define a rectangle or square into which the BM may be deposited. The beams may, further, be curved. Many configurations for beams in a personal care product are shown in Figures 1-6. The beams may be oriented such that the strips of fabric are all facing in the same direction or they may be oriented such that individual strips are perpendicular to the strips in adjacent beams.

Turning to the drawings, Figure 1 shows the simplest configuration of the BM containment system of this invention whereby beams (1 ) form a box which provides void volume. Note that the layers of fabric comprising each beam are perpendicular to layers of fabric forming the beam next to it. Figure 2 shows the configuration of Figure 1 wherein the fabric layer orientation in all of the beams is parallel.

Figure 3 shows another configuration wherein the beams approximate a capital "H" with another vertical member in the center.

Figure 4 shows a BM containment system wherein the outer beams are curved. Figure 5 shows a BM containment system similar to Figures 1 and 2 but with the addition of two vertical beams within the box.

Figure 6 graphically illustrates the change in thickness versus load for a number of beams of different materials and methods of construction. This Figure 6 is discussed more fully below. Examples

A number of Examples of materials were tested in order to determine the most suitable orientation of fibers for the containment area of this invention. All fibers were side-by-side conjugate fibers of polypropylene and polyethylene made according to the spunbond process. The fibers were spun according to US patent 5,382,400 to Pike et al. Fabrics were produced at 1 osy (33.9 gsm), 2 osy (67.8 gsm), 3 osy (101.7 gsm) and 6 osy (203.4 gsm) with both high and low amounts of crimp as defined by the patent. The fabrics were slit in the cross-machine direction and adhesively bonded together into a laminate about 1/4 inches (6.4 mm) thick and slit again to result in approximately square beams. Each laminate was tested according to the compression test. The graph of Figure 6 shows the percentage of original thickness on the y-axis and the pressure in psi applied to each laminate beam on the x-axis. The numbers on the graph correspond to the laminate numbers as identified as follows: Laminate number 1 is a laminate made with 1 osy fabric of high crimp fiber. Number 2 is a laminate made with 2 osy fabric of high crimp fiber. Number 3 is a laminate made with 3 osy fabric of high crimp fiber. Number 4 is a laminate made with 3 osy fabric of low crimp fiber. Number 5 is a laminate made with 6 osy fabric of low crimp fiber. Number 6 is a laminate made with 6 osy fabric of high crimp fiber. Number 7 is a laminate made with 6 osy fabric of low crimp fiber oriented in the Z direction. Number 8 is a laminate made with 6 osy fabric of high crimp fiber oriented in the Z direction. As can be clearly seen by the graph, laminate number 7 retains a substantial amount of its original thickness, more than 80 percent, under a compressive load of 2 psi.

The BM containment system of this invention may be located next to the backsheet or the retention material. One possible diaper design also has surge material in the urine intake area, the BM containment system below a liner in the BM intake area and retention/storage material at either end of the diaper.

The liner is sometimes referred to as a bodyside liner or topsheet and is adjacent to the surge material. The liner material is the layer against the wearer's skin and so the first layer in contact with liquid or other exudate from the wearer. The liner further serves to isolate the wearer's skin from the liquids held in an absorbent structure and should be compliant, soft feeling and non-irritating.

Various materials can be used in forming the bodyside liner of the present invention, including apertured plastic films, woven fabrics, nonwoven webs, porous foams, reticulated foams and the like. Nonwoven materials have been found particularly suitable for use in forming the bodyside liner, including spunbond or meltblown webs of polyolefin, polyester, polyamide (or other like fiber forming polymer) filaments, or bonded carded webs of natural polymers (for example, rayon or cotton fibers) and/or synthetic polymers (for example, polypropylene or polyester) fibers. For example, the bodyside liner can be a nonwoven spunbond web of synthetic polypropylene filaments. The nonwoven web can have a basis weight ranging from about 10.0 grams per square meter (gsm) to about 68.0 gsm, and more particularly from about 14.0 gsm to about 42.0 gsm, a bulk or thickness ranging from about 0.13 millimeter (mm) to about 1.0 mm, and more particularly from about 0.18 mm to about 0.55 mm, and a density between about 0.025 grams per cubic centimeter (g/cc) and about 0.12 g/cc, and more particularly between about 0.068 g/cc and about 0.083 g/cc. Additionally, the permeability of such nonwoven web can be from about 150 Darcy to about 5000 Darcy. The nonwoven web can be surface treated with a selected amount of surfactant, such as about 0.28% Triton X-102 surfactant, or otherwise processed to impart the desired level of wettability and hydrophilicity. If a surfactant is used, it can be applied to the web by any conventional means, such as spraying, printing, brush coating and the like.

The surge layer is most typically interposed between and in intimate, liquid communicating contact with the bodyside liner and another layer such as a distribution or retention layer. The surge layer is usually subjacent the inner (unexposed) surface of bodyside liner. To further enhance liquid transfer, it can be desirable to attach the upper and/or lower surfaces of the surge layer to the liner and the distribution layer, respectively. Suitable conventional attachment techniques may be utilized, including without limitation, adhesive bonding (using water-based, solvent-based and thermally activated adhesives), thermal bonding, ultrasonic bonding, needling and pin apertuhng, as well as combinations of the foregoing or other appropriate attachment methods. If, for example, the surge layer is adhesively bonded to the bodyside liner, the amount of adhesive add-on should be sufficient to provide the desired level(s) of bonding, without excessively restricting the flow of liquid from the liner into the surge layer. One exemplary surge material may be found in US Patent Application number 08/755,514, assigned to the same assignee as this application and entitled HIGHLY EFFICIENT SURGE MATERIAL FOR ABSORBENT ARTICLES which presents a surge material which is a web of wettable fibers of 30 microns in diameter or less which is substantially uniform and where the web has a permeability of between about 250 and 1500 Darcys and a capillary tension between 1.5 and 5 cm.

Various woven fabrics and nonwoven webs can be used to construct a surge layer. For example, the surge layer may be a nonwoven fabric layer composed of a meltblown or spunbond web of polyolefin filaments. Such nonwoven fabric layers may include conjugate, biconstituent and homopolymer fibers of staple or other lengths and mixtures of such fibers with other types of fibers. The surge layer also can be a bonded carded web or an airlaid web composed of natural and/or synthetic fibers. The bonded carded web may, for example, be a powder bonded carded web, an infrared bonded carded web, or a through-air bonded carded web. The bonded carded webs can optionally include a mixture or blend of different fibers, and the fiber lengths within a selected web may range from about 3 mm to about 60 mm. Exemplary surge layers can have a basis weight of at least about 0.50 ounce per square yard (about 17 grams per square meter), a density of at least about 0.010 gram per cubic centimeter at a pressure of 68.9 Pascals, a bulk of at least about 1.0 mm at a pressure of 68.9 Pascals, a bulk recovery of at least about 75 percent, a permeability of about 500 to about 5000 Darcy, and a surface area per void volume of at least about 20 square centimeters per cubic centimeter. Examples of surge materials may be found in US Patent 5,490,846 to Ellis et al. and in US Patent 5,364,382 to Latimer. The surge layer may be composed of a substantially hydrophobic material, and the hydrophobic material may optionally be treated with a surfactant or otherwise processed to impart a desired level of wettability and hydrophilicity. The surge layer can have a generally uniform thickness and cross- sectional area.

The distribution layer must be capable of moving liquid from the point of initial deposition to where storage is desired. Distribution must take place at an acceptable rate such that the target insult area, generally the crotch area, is ready for the next insult. The time between insults can range from just a few minutes to hours, generally depending on the age of the wearer. In order to achieve this transportation function, a distribution layer must have a high capillary tension value. Capillary tension in distribution and other materials not containing superabsorbents is measured simply by the equilibrium vertical wicking height of a 8.5 g/l saline solution. A successful distribution layer must have a capillary tension greater than the adjacent material from which it receives liquid (on the side toward the wearer) and preferably a capillary tension of at least about 15 cm. Because of the generally inverse relationship between capillary tension and permeability, such a high capillary tension indicates that the distribution layer will usually have a low permeability. Materials from which the distribution layer may be made include woven fabrics and nonwoven webs, foams and filamentious materials. For example, the distribution layer may be a nonwoven fabric layer composed of a meltblown or spunbond web of polyolefin, polyester, polyamide (or other web forming polymer) filaments. Such nonwoven fabric layers may include conjugate, biconstituent and homopolymer fibers of staple or other lengths and mixtures of such fibers with other types of fibers. The distribution layer also can be a bonded carded web, an airlaid web or a wetlaid pulp structure composed of natural and/or synthetic fibers, or a combination thereof. The distribution layer may have a basis weight of from 35 to 300 gsm, or more preferably from 80 to 200 gsm, a density of between about 0.08 and 0.5 g/cc and a permeability between about 50 and 1000 Darcys. The backsheet is sometimes referred to as the outer cover and is located the farthest from the wearer. The outer cover is typically formed of a thin thermoplastic film, such as polyethylene film, which is substantially impermeable to liquid. The outer cover functions to prevent body exudates contained in an absorbent structure from wetting or soiling the wearer's clothing, bedding, or other materials contacting the diaper. The outer cover may be, for example, a polyethylene film having an initial thickness of from about 0.5 mil (0.012 millimeter) to about 5.0 mil (0.12 millimeter). The polymer film outer cover may be embossed and/or matte finished to provide a more aesthetically pleasing appearance. Other alternative constructions for outer cover include woven or nonwoven fibrous webs that have been constructed or treated to impart the desired level of liquid impermeability, or laminates formed of a woven or nonwoven fabric and thermoplastic film. The outer cover may optionally be composed of a vapor or gas permeable, microporous "breathable" material, that is permeable to vapors or gas yet substantially impermeable to liquid. Breathability can be imparted in polymer films by, for example, using fillers in the film polymer formulation, extruding the filler/polymer formulation into a film and then stretching the film sufficiently to create voids around the filler particles, thereby making the film breathable. Generally, the more filler used and the higher the degree of stretching, the greater the degree of breathability.

The BM containment system of this invention is placed on the wearer side of a personal care product like a diaper, adjacent to and between the anal opening and the liner. The system may be adhered with hook and loop type fasteners like Velcro® fasteners, adhesive, ultrasonic bonding, or other known bonding means. It may be placed by a diaper manufacturer or by the caretaker, which may allow for more accurately locating the system adjacent the BM target zone.

As can be seen from the above description, there is herein provided a BM containment compartment which can take in BM and provide void volume for containing the BM. The BM compartment, due to it's function of collecting and isolating the BM, serves to minimize skin contact with the BM by preventing the spread of BM outside the BM compartment. This also serves to reduce the mixing of BM and urine since such mixing exacerbates the effect of enzymatic BM irritants on the skin. Although only a few exemplary embodiments of this invention have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention as defined in the following claims. In the claims, means plus function claims are intended to cover the structures described herein as performing the recited function and not only structural equivalents but also equivalent structures. Thus although a nail and a screw may not be structural equivalents in that a nail employs a cylindrical surface to secure wooden parts together, whereas a screw employs a helical surface, in the environment of fastening wooden parts, a nail and a screw may be equivalent structures.

Claims

What is claimed is:

1. A BM containment system for personal care products comprising beams capable of substantially retaining their original dimensions when subjected to a pressure of about 2 psi, while providing a void volume of at least 60 cc.

2. The system of claim 1 wherein said beams comprise a material selected from the group consisting of nonwoven fabric and foam.

3. The system of claim 2 wherein said material is nonwoven fabric and is made according to a spunbond process.

4. The system of claim 3 wherein said spunbond nonwoven fabric comprises conjugate fibers.

5. The system of claim 4 wherein said fibers are polypropylene/polyethylene side-by-side fibers having a low level of crimp.

6. The system of claim 5 wherein said conjugate fibers are aligned in a Z-direction.

7. A personal care product selected from the group consisting of diapers, training pants, absorbent underpants and adult incontinence products comprising the system of claim 1.

8. The product of claim 7 wherein said personal care product is an adult incontinence product.

9. The product of claim 7 wherein said personal care product is a diaper.