HK1025028A - Disposable absorbent article having improved in-use storage capacity for low and medium low viscosity faeces - Google Patents

Description

Disposable absorbent article having improved ability to store low and medium viscosity fecal material

The present invention relates to disposable absorbent articles such as diapers, adult incontinence products and the like, and more particularly to disposable absorbent articles having the ability to store low and medium low viscosity fecal material so that the skin of the wearer does not come into contact with the fecal material, thereby reducing leakage and allowing easier cleaning of the wearer when the soiled disposable absorbent article is removed.

Disposable absorbent articles such as diapers, adult incontinence products and the like are well known products. Such disposable absorbent articles collect and retain urine and feces excreted by and deposited on the wearer. While there have been numerous attempts and efforts to improve the urine management of disposable absorbent articles, relatively few attempts have been made to improve the feces management of disposable absorbent articles, particularly low or medium viscosity feces management.

The amount, frequency and consistency of feces excreted by the wearer vary widely depending on the age (newborn or adult) or the condition of the wearer (nutrition, illness, etc.). That is, depending on physiological conditions, daily excretions can average 100 grams to over 1000 grams, while individual daily excretions are less than 40 grams. The frequency of defecation in infants is generally high (more than 5 times per day in newborns), and this frequency decreases with age to about once per day in adults. The composition of the feces also varies widely, but within the scope of the present invention, the amount of water is of most interest, which accounts for about 70% to about 90% of the total output. Accordingly, the consistency of such excreta (often referred to as "feces", abbreviated as ". BM") ranges from "dry and hard", "pasty" to "thin and soft". Within the scope of the present invention, this consistency is closely related to the professional metering of the viscosity.

It is clear that the disposal of such substances requires the use of a structure that is totally different from the structure used to "store" or absorb fluids such as urine. For the latter, the pore size should be smaller (it is even as small as a molecular scale, such as that provided by "superabsorbent materials", although this may have other effects). Whereas for storing faeces a sufficiently open/large aperture is required in order to be able to receive faeces. Feces have a higher viscosity than urine. This is required for both the topsheet (body facing side) material of the absorbent article and the material of the corresponding substance which is designed to be stored.

Prior attempts to improve the handling of feces have included providing a first topsheet that is in close proximity to the wearer and has an aperture. The hole will be aligned with the anus so that faeces pass through the hole into the void space. The first topsheet may have a plurality of elastic panels so as to be conformable to the wearer's skin and/or may have linear elastic bands. Improvements have also been made in this area of technology, such as selecting the most suitable material properties of the primary topsheet. This optimization makes the first topsheet more comfortable for the wearer and allows a single disposable absorbent article to fit a wide range of wearers. Examples of such processes are given in EP-A-0359410, EP-A-0386816, EP-A-0644747.

Improvements of this type in the field of disposable absorbent articles have also included the addition of liners. A liner may be positioned between the first topsheet and the absorbent core to ensure that there is a void space for receiving feces. Examples of such processes are given in US-A-4,778,459, FR-2495899, WO90/14063, WO 93/12748.

Other attempts to improve upon such prior art articles have included providing a barrier for limiting the movement of feces to specific portions of the disposable absorbent article. Such barriers are capable of limiting the contact of feces with the wearer's skin to a lesser extent than disposable absorbent articles without barriers. Such A process is disclosed in U.S. Pat. No. 5,514,121, EP-A-0486006.

However, attempts at fecal management do not address this particular situation when very thin and soft feces are present, which is common for smaller children, particularly nursing infants. Mothers refer to this very low viscosity stool as "thin soft stool (or BM)" and the higher consistency stool as "pasty BM" (which is still less viscous than "dry hard BM"). Such lower viscosity feces can readily migrate within the disposable absorbent article under the influence of gravity and the movements and pressures generated by the wearer.

The migration of feces often causes them to migrate across the surface of the absorbent article toward the boundaries of the disposable absorbent article, thereby increasing the likelihood of leakage. The migration of feces can also make it more difficult to clean by spreading it on the wearer's skin. To clean the wearer, the caregiver must scrub the entire area of the skin to which the feces are attached, and the area that is generally contaminated is large.

A series of prior attempts to address low viscosity fecal management can be seen in U.S. patent 5,342,338. This application describes a disposable absorbent article having a first topsheet with high topsheet permeability and a second topsheet with lower topsheet permeability underlying the first topsheet.

PCT US94/08958 also discloses a disposable absorbent article which reduces the likelihood of leakage of low viscosity fecal material from the disposable absorbent article, the purpose of the absorbent article being to combine a high topsheet permeability topsheet with a fecal storage material to minimize low viscosity fecal material clinging to the wearer's skin when the disposable absorbent article is removed.

However, the above-mentioned prior art relies on the movement during use to create storage space, such as to detach the topsheet as far as possible from the underlying fluid storage structure reinforced with elastics. It is therefore an object of the invention to provide such a storage space at the beginning of use and also to maintain it during use.

Thus, it is an object of the present invention to provide a structure which improves the handling properties of feces, particularly of feces of medium viscosity, i.e., a structure which improves the feces handling capacity.

It is a further object of the invention to allow selection of suitable materials for such improved structures with respect to the number of materials used and the size of the materials by determining the storage capacity of the materials for medium viscosity faeces.

Disposable absorbent articles such as diapers include medium viscosity fecal storage materials that have improved fecal storage capacity, particularly of medium and low viscosity. Such a storage material is characterized in that it has a storage capacity for faeces of at least 20 g/g, preferably more than 35 g/g, when tested according to the described test for a medium viscosity faeces storage capacity.

While the specification and claims herein have been set forth with particularity and detail in connection with what is presently deemed to be the most practical and preferred embodiment of the invention, it is believed that the invention will be better understood from the following description taken in conjunction with the accompanying drawings, in which like reference numerals are used to designate substantially identical components;

FIGS. 1A and 1B are top plan views of a disposable absorbent article of the present invention (with portions broken away) showing two different arrangements of the absorbent core and storage material;

FIGS. 2A and 2B are vertical sectional views taken along section line 2-2 in FIGS. 1A and 1B, illustrating the relationship between the first topsheet, the fecal storage material and the absorbent core;

FIGS. 3A and 3B are vertical sectional views taken along section line 3-3 in FIGS. 1A and 1B, illustrating the relationship between the first topsheet, the fecal storage material and the absorbent core;

figure 4 is a schematic side view of an apparatus that may be used to measure the performance of a disposable absorbent article.

As used herein, the term "absorbent article" refers to devices which are used to absorb and store bodily waste, and more specifically, refers to devices which are placed against or in proximity to the body of the wearer to absorb and store the various exudates discharged from the body. The term "disposable" is used herein to describe absorbent articles which are not intended to be laundered or otherwise restored or reused as absorbent articles (i.e., they are intended to be discarded after a single use and, preferably, to be recycled, blended or otherwise disposed of in an environmentally compatible manner). A preferred embodiment of the absorbent article of the present invention is a disposable absorbent article-the diaper 20 shown in figure 1. The term "diaper" as used herein refers to an absorbent article generally worn by infants or incontinent adults about the lower portion of their torso.

Figure 1 is a plan view of a diaper 20 of the present invention in its flat-out, uncontracted state (i.e., with the elastic induced contraction pulled away) with portions of the structure being cut away to more clearly show the construction of the diaper 20 and with the portion of the diaper 20 that faces or is positioned against the wearer, i.e., the interior surface of the diaper, facing the viewer. As shown in figure 1, the diaper 20 preferably comprises a first liquid pervious topsheet 24, a liquid impervious backsheet 26 joined to the first topsheet 24, a liquid pervious fecal storage material 25 positioned between the first topsheet 24 and the backsheet 26 and, optionally, an absorbent core 28 positioned between the fecal storage material 25 and the backsheet 26. The absorbent core 28 is generally designed to absorb urine and, of course, may also absorb some amount of moisture from feces, such as feces. Thus, the fecal storage material 25 can be separate from the absorbent core 28, or integral with the absorbent core 28, or mixed with the absorbent core. The diaper 20 may also have elastic side panels (not shown), elastic leg cuffs (not shown), elastic waist features (not shown), and a fastening assembly, generally indicated at 36, comprising a plurality of belt-like tabs.

The diaper 20 shown in figure 1 also has a first waist region 27, which is juxtaposed with the front of the wearer during wear of the diaper 20, a second waist region 29, opposite the first waist region 27, which is juxtaposed with the back of the wearer during wear of the diaper 20, a crotch region 31, which is located between the first waist region 27 and the second waist region 29, and a periphery defined by the outer edges of the diaper 20, wherein the longitudinal edges of the diaper are designated 33 and the end edges are designated 35. The inner surface of the diaper 20 is the portion of the diaper that is adjacent to the body of the wearer during use (i.e., the inner surface is generally formed by at least a portion of the first topsheet 24 and other components that are joined to the first topsheet 24). The outer surface of the diaper 20 is that portion of the diaper which, in use, faces away from the wearer's body (i.e., the outer surface is generally formed by at least a portion of the backsheet 26 and the other components associated with the backsheet 26).

In the embodiment of the diaper 20 shown in figure 2, the first topsheet 24 and the backsheet 26 have length and width dimensions generally greater than the length and width dimensions of the absorbent core 28. The first topsheet 24 and the backsheet 26 extend beyond the boundaries of the absorbent core 28 to form the periphery of the diaper 20. Alternatively, the fecal storage material 25 can (but is not required to) extend beyond the boundaries of the absorbent core 28 and be joined to the backsheet 26 to form the periphery of the diaper 20, while the first topsheet 24 is smaller than or coextensive with the absorbent core 28. While the first topsheet 24, the fecal storage material 25, the backsheet 26 and the absorbent core 28 can be assembled in a variety of known configurations, the following patent disclosures are preferred: U.S. Pat. No. 3,860,003 to Kenneth B.Buell, 1/14 of 1975 entitled "controllable Side ports for DisposableDiaper"; and U.S. Pat. No. 5,151,092 to Kenneth B. Buell et al, 9/29 of 1992, entitled "Absorbent Article With Dynamic Elastic Water heating A Presponded reactive Flexible Hinge".

The absorbent core 28 may be any absorbent device which is generally compressible, compliant, non-irritating to the wearer's skin, and capable of absorbing and storing liquids such as urine. As shown in figure 1, the absorbent core 28 has a garment facing surface, a body facing surface, side edges and waist edges. The absorbent core 28 may be manufactured in a variety of sizes and shapes (e.g., rectangular, funnel, "T" shaped, asymmetric, etc.) and from a variety of liquid-absorbent materials commonly used in disposable diapers and other absorbent articles, such as comminuted wood pulp, which is generally referred to as "airfelt". Examples of other suitable hygroscopic materials include: a creped cellulose filler; comprises a coformed meltblown polymer; chemically stiffened, modified or cross-linked cellulosic fibers; tissue paper comprising tissue wraps, tissue stacks; a moisture absorbing foam; a moisture-absorbing sponge; a superabsorbent polymer; absorbent gelling materials or other equivalent materials, or combinations of materials.

The shape and configuration of the absorbent core 28 may also be varied (e.g., the absorbent core 28 may have regions of varying caliper, a hydrophilicity gradient, a superabsorbent gradient, or low average density and low average basis weight acquisition regions; or may comprise one or more plies or structures). However, the total absorbent capacity of the absorbent assembly should be compatible with the designed load bearing capacity and use of the diaper 20. And the size and absorbent capacity of the absorbent core 28 may correspond to the wearer's variation from an infant to an adult.

Examples of absorbent structures useful as the absorbent core 28 are described in the following patent documents: U.S. Pat. No. 4,610,678 to Weisman et al, entitled "High-DensityAbsorbent Structures", on 9.9.1986; U.S. Pat. No. 4,673,402 to Weisman et al, entitled "Absorbent articules With Dual-Layered Cores", 16.6.1987; U.S. Pat. No. 4,888,231 to Angstadt, 12/19/1989, entitled "Absorbent Corehing adapting Layer"; and U.S. Pat. No. 4,834,735 to Alemany et al, 3/30, 1989, entitled "High Density Absorbent Members Having Low Tower Density and Low Basis Weight Acquisition Zones".

The backsheet 26 is adjacent the garment-facing surface of the absorbent core 28 and is preferably joined thereto by attachment means (not shown) well known in the art. As used herein, the term "joined" encompasses configurations whereby one element is directly secured to another element by direct attachment to the other element, and configurations whereby one element is indirectly secured to another element by attachment to intermediate elements that are in turn attached to the other element.

For example, the backsheet 26 may be secured to the absorbent core 28 by a uniform continuous layer of adhesive, a patterned layer of adhesive, or an array of discrete lines, spirals, or spots of adhesive. A satisfactory adhesive has been found to be manufactured by h.b. fuller Company of st.paul, Minnesota under product designation HL-1258. One preferred attachment means is an open graphic web of adhesive filaments as described in U.S. Pat. No. 4,573,986 entitled "Disposable Waster-Containment Gargent" issued to Minetola et al, 3/4 1986. More preferred attachment means include strands of adhesive fibers wound in a helical pattern, as described in U.S. patent 3,911,173 to Sprague, jr, 10/7 1975; us patent 4,785,996 to Ziecker et al, 11/22/1978; and as shown in the description of the apparatus and method in U.S. patent 4,842,666 issued to Werenicz at 27.6.1989. Additionally, the attachment means may include thermal, pressure, ultrasonic, dynamic mechanical, or other suitable attachment means, or combinations thereof, in a known manner.

The backsheet 26 is impervious to fluids such as urine and feces and is preferably formed of a thin plastic film, although other flexible liquid impervious materials may be used. As used herein, the term "flexible" means that films and other suitable backsheet materials are compliant and will readily conform to the shape and contours of the human body.

The backsheet 26 prevents the exudates absorbed and contained by the absorbent core 28 from wetting articles which contact the diaper 20, such as bedsheets and undergarments. Thus, the backsheet 26 may be a woven or nonwoven material, a polymeric film such as a thermoplastic film of polyethylene or polypropylene, or a composite of a filmed nonwoven material. The backsheet is preferably a thermoplastic film having a thickness of about 0.012 millimeters (0.5 mil) to about 0.051 millimeters (2.0 mils). Particularly preferred materials for use as the backsheet include, for example, RR8220 blown films and RR5475 injection molded films manufactured by Tredegar Industries, Inc. of TerreHaute, Indiana. The backsheet 26 is preferably embossed and/or matte finished to provide a garment-like appearance. Further, the backsheet 26 is desirably impervious to exudates while permitting vapors to escape from within the diaper 20 (i.e., the backsheet is breathable).

The diaper 20 further comprises elastic leg cuffs (not shown) which may enhance the storage of the diaper to liquids and other human waste. Each elastic leg cuff may have different embodiments to reduce leakage of body exudates in the leg region. (leg cuffs may also sometimes be referred to as leg cuffs, side flaps, barrier cuffs, or elastic cuffs). U.S. patent No. 3,860,003 describes a disposable diaper having a contractible leg opening having a side flap and one or more elastic members, thereby obtaining an elastic leg cuff (liner). U.S. Pat. No. 4,909,803, to Azizz et al, 3/20/1990, entitled "dispersible Absorbent Article Having elastic Flaps", Having "standing" elastic Flaps, and commonly assigned to the assignee of the present application, discloses a Disposable diaper Having "standing" elastic Flaps (cuffs) to improve storage in the leg regions. U.S. patent No. 4,695,278 to Lawson, 22/9/1987, entitled "Absorbent Article Having Dual Cuffs", Having common assignee herewith, describes a disposable diaper Having a Dual cuff comprising a liner cuff and a barrier cuff.

The diaper 20 preferably further includes an elastic waist feature (not shown) to enhance fit and retention characteristics. The elastic waist features are portions or zones of the diaper 20 that are capable of being elastically extended and retracted to dynamically fit the waist of the wearer. The elastic waist feature extends longitudinally outward from at least one waist edge of the absorbent core and generally forms at least a portion of an end edge of the diaper 20. While a diaper may be constructed with only one waist feature, disposable diapers are generally constructed with two elastic waist features, one in the first waist region 27 and one in the second waist region 29. Further, while the elastic waist feature or any of its constituent elements may be a separate component secured to the diaper 20, the elastic waist feature is preferably configured as an extension of other components of the diaper 20, such as the backsheet 26, or the topsheet 24, or preferably both the backsheet 26 and the topsheet 24. The elastic waistband 34 can be constructed in a variety of different configurations, including U.S. Pat. No. 4,515,595 to Kievit et al, 5/7/1985 and U.S. patent application Ser. No. 07/715,152, referenced above.

The diaper 20 further includes a fastening component 36 that forms a lateral closure to maintain the first waist region 27 and the second waist region 29 in an overlapping configuration, which provides a lateral tensile force about the periphery of the diaper 20 to hold the diaper 20 on the wearer. Examples of fastening assemblies are disclosed in the following patents: U.S. Pat. No. 4,846,815 to Scripps at 11/7/1989, entitled "Disposable cutter bathing improved Fastening Device"; U.S. patent 4,890,060 entitled "dispersible dictionary With Improved Hook fasteneration" issued on 16.1990.1.1990; U.S. Pat. No. 4,946,527 entitled "Pressure-Sensitive Adhesive Fastener And Method of Making Same", issued to Battrell on 7.8.1990; U.S. Pat. No. 3,848,594 to Buell on 11/19/1974 entitled "Tape fastening System for Disposable adapter"; U.S. patent 4,662,875 entitled "adsorbent Article" issued to Hirotsu et al, 5.5.1987; and U.S. patent application 07/715,152, previously incorporated by reference.

The diaper 20 is preferably worn on the wearer in the following manner; one of the waist regions, preferably the second waist region 29, is placed under the back of the wearer and the remainder of the diaper 20 is pulled out from between the legs of the wearer. Such that the other waist region, preferably the first waist region 27, is disposed in front of the wearer. The tape tab 36 of the fastening assembly is then torn away from the anti-adhesive portion. The person wearing the diaper then wraps the side panels 30 around the body of the wearer while still grasping the next section. The fastening assembly is fastened to the outer surface of the diaper 20 so as to form two side closures.

Each of the first topsheet 24 and the fecal storage material 25 has two major surfaces. The first topsheet 24 has a first major surface facing the wearer and an opposite second major surface facing the storage material 25. The fecal storage material 25 has a first major surface oriented toward the first topsheet 24 and a second major surface oriented toward the absorbent core 28 (if the absorbent core is separate from the fecal storage material 25).

The first topsheet 24 is juxtaposed with (but not necessarily adjacent to) the body-facing surface of the fecal storage material 25 and is preferably joined to either the backsheet 26 or the fecal storage material 25 by means well known in the art. Suitable attachment means are mentioned above in connection with the attachment of the backsheet 26 to the absorbent core 28. In a preferred embodiment of the present invention, the first topsheet 24 is joined directly to the backsheet 26 at the periphery of the diaper.

The first topsheet 24 is preferably compliant, soft feeling, and non-irritating to the wearer's skin. Moreover, the first topsheet 24 is preferably liquid pervious, permitting liquids (e.g., urine) to readily penetrate through its entire thickness. A wide range of materials are suitable for making the first topsheet 24, such as porous foams, reticulated foams, apertured plastic films, or woven or nonwoven webs of natural fibers (e.g., wood or cotton fibers), synthetic fibers (e.g., polyester or polypropylene fibers), or a mixture of natural and synthetic fibers. A variety of techniques may be employed to make the first topsheet 24. For example, the first topsheet 24 may be a nonwoven web of fibers spunbonded, carded, wet-laid, meltblown, hydroentangled, or a combination thereof. Further options for the first topsheet 24 include carded/carded composites, fibrous webs formed by hydroentanglement on a forming wire using means well known to those skilled in the art, through-air bonding, and the like. A particularly preferred material is a perforated formed film having a central layer of perforated film covered on both sides with a nonwoven material, and the nonwoven material also having perforations which coincide with the perforations of the film.

U.S. Pat. No. 5,342,338 has taught the importance of "topsheet permeability to low viscosity fecal material (e.g., feces)" as described herein. Thus, assuming a diaper having a surface area of at least 192 square centimeters (20 square inches), the diaper 20 should have a topsheet through capacity of at least about 0.20 grams per square inch. A preferred example is a combination of an apertured film/nonwoven laminate (PANTEX18125X) as the backsheet and an apertured film (TEREDEGAR X5790).

However, these topsheets do not have sufficient permeability to optimize fecal management performance, especially when the feces are highly viscous or thick. In these cases, permeability is not only related to ease of penetration through the component, but also to the self-storage capacity of the storage material. Thus, the top through test has been modified to screen out particularly suitable materials.

The "medium viscosity fecal storage capacity test" was performed on a flat sample specimen (at 23 grade Celsius standard test conditions and 50% relative humidity) having dimensions of 10 cm by 10 cm.

A plexiglass plate of the same size (10 cm x 10 cm) and thickness of 5 mm was covered over the material. In the centre of the disc there is a hole of 3 cm diameter, on which a circular plexiglas tube is fitted, also of 3 cm internal diameter. The height of the tube was 20 cm and a cylinder was placed inside the tube so that it could slide smoothly inside the tube. (the tube is mounted so firmly that the test fluid described below cannot be squeezed out under the application of pressure.) Another part of the set-up is a weight that loads the cylinder so that the pressure applied to the lower region of the apparatus is 5171 Pa (0.75psi) and the pressure applied to the sample by a weight of 305 grams placed on a plexiglas plate is 427 Pa (0.0608 psi).

In order to be able to determine the material handling properties of low-viscosity substances and of medium-viscosity substances, it was possible not only to use the test fluid CARBOPOLETD 2050 in aqueous solution in this particular test, commercially available from BF Goodrich Chemical (Deutschland) GmbH, Neuss, Germany, for example. A particularly suitable solution contains 0.5% polymer and, after careful compounding according to standard procedures required by the supplier, has a viscosity of about 16000cps as measured by a Brookfield viscometer, again according to the procedures given by the supplier.

For this test, a pre-weighed fecal storage test specimen is cut to the desired size and placed between two similarly pre-weighed pieces of (i) ordinary PE film (e.g., backsheet material for a diaper) and (ii) a standardized topsheet of the same dimensions. For high viscosity materials, a hole is required. The tested apertured film/nonwoven laminate was provided by panax.

These laminated composites consist of two conventional spunbonded webs of PP fiber mesh (about 14 grams per square meter) and a layer of PE film of about 20 mm sandwiched in between. The mesh is substantially hydrophobic PP. The apertures are essentially rectangular apertures having a size of 0.5 square millimeters and are formed by punching all three plies with a heated embossing pattern roll. About 40 holes per square centimeter, the area of the holes occupying about 20% of the total area. During the hole formation, bonding occurs and some of the fibers melt around the hole. Such materials are described in detail in EP 0207904.

These plies are carefully placed centrally under the plexiglas plate. Then 20 grams of test fluid was placed into the tube, a cylinder was carefully mounted into the tube, and a weight was placed on the plexiglas plate and cylinder.

After 10 minutes, the plexiglass disk was carefully removed so that no more test fluid flowed into or was retained by the laminate after 10 minutes of absorption. The three-ply sheets were carefully weighed and then again carefully separated without allowing the test fluid to flow from one sheet to the other.

After weighing the test specimen, the area of contamination of the specimen by the fluid is determined by conventional means, the diameter of the circle is measured if the area of contamination substantially approximates a circle, or conventional computer image processing techniques may be employed, which may include the step of manually converting the contaminated portion into a clear portion.

The final direct reading of the test is the amount of material absorbed by the sample and the area of contamination during the test under the applied pressure. To better compare materials and designs, the basic storage capacity of a material and the storage capacity of a material can be calculated.

First, the basic storage capacity (grams per square centimeter) of a material is calculated by: the total amount of material absorbed by the sample (grams) is divided by the area contaminated (centimeters). This parameter can be used to design the dimensions of the faecal storage material.

The storage capacity of a material (grams per gram) is the basis storage capacity of the material divided by the basis weight (grams per square centimeter), which gives the amount of fluid absorbed per unit amount of material used. This parameter is important for the material selection of the faecal storage material.

Without being bound by theory, it is believed that the absorption properties of medium viscosity stools are primarily characterized by capillary transport properties, which readily create available storage space. Thus, porosity and dependence on applied pressure are very important. However, a balancing problem is now encountered in that it is difficult to compromise between softness and absorption capacity of the material. To compare these properties of the materials, the materials were subjected to a rebound test.

The samples were tested using conventional compression/pressure analysis equipment, such as an INSTRON tester. The constant crosshead speed of the tester was 10 mm per minute and the position of the crosshead could be read at a certain pressure. More generally, a compression curve is plotted and the thickness of the sample is determined in the graph at pressures of 1379 pa, 2578 pa, 2448 pa, 5516 pa and 6895 pa (0.2, 0.4, 0.5, 0.8 and 1.0psi), respectively. After the maximum compression was reached, the pressure was reduced to 552 pa (0.08psi) over 5 seconds and the thickness was measured again. This procedure was repeated three times and the readings taken at each time were averaged. This allows the thickness readings to be used to calculate different thickness reductions of the material after a given pressure or operating process.

Materials suitable for use in the present invention are open fiber structures, while particularly suitable materials are air-laid (airlad), through air bonded (air through) nonwoven webs obtained by permanently incorporating eccentric PE sheath/PP core BiCo fibers into PE resin. Such a mesh has an open type elastic fiber structure without sacrificing the softness of the material.

Examples of the invention

To illustrate the present invention, applicants have made airlaid, through-air bonded nonwoven fabrics on an airlaid and through-air bonding line. The starting material used was an eccentric, PE sheath/PP core BiCo fiber permanently incorporated in PE resin, produced by DANAKLON Demark, product code ESEWA, thickness 6.7 dTeX. The mesh is described in detail in WO 94/28838 in the name of Palumbo, and the fibres are used in EP0340763 in the name of Hansen.

A comparative example is A porous formed film such as that provided by TREDAGAR, product code X5790, as mentioned in the above-mentioned patent U.S. Pat. No. 5,342,338.

TABLE 1

Comparative examples of test materials

Basis weight [ gsm ] 60.062.2

Thickness (@552 Pa) [ mm ] 2.661.69

Density (@552 Pa) [ g/cm ] 0.0230.037

Reduction of thickness

Maximum pressure [% ] 52.235.9

After cyclic operation [% ] 19.418.4

Total test fluid absorption [ g ] 10.06.0

Area of pollution [ cm²] 44.4 54.7

Material absorption capacity [ g/g ] 37.517.6

Basic absorption capacity of material [ g/cm ]²] 0.23 0.11

As can be clearly seen, the medium viscosity absorbent capacity of the test material is significantly increased, and its basic absorbent capacity is also greatly increased.

Absorbent article

Without being bound by theory, it is believed that when feces are immobilized in the storage material, it no longer contaminates or irritates the skin of the wearer. Further, low viscosity feces wick away moisture through the capillary action of the fluid handling component.

While such high absorbency is a preferred characteristic of the materials used, the choice of materials with high basis storage capacities is more flexible in designing absorbent articles with better fit (e.g., smaller absorbent articles) or where fecal storage problems may be encountered in improving urine handling capacity.

Thus, according to the present invention, an absorbent article having a fecal storage material can be designed to simply insert the fecal storage material between the absorbent core 28 and the topsheet 24. In this way, the amount (basis weight) and size of the fecal storage material can be easily adjusted to the needs of different populations of wearers. Thus, for example, to design an absorbent article to store 100 grams of feces, a sheet of material 3 grams, or about 500 square centimeters, or about 33 centimeters long by 15 centimeters wide by way of example, is required. This piece of material may for example cover substantially the entire absorbent core of a typical size MAXI diaper. Such a design is shown in fig. 1A to 3A, respectively.

Also preferred designs are shown in panels B, respectively, where the required material size is significantly reduced due to the increased basis weight of the faeces storage material. In this way the fecal storage material can preferably be placed in the rear portion of the absorbent article so that it is directed towards the anus and even further extending towards the back side of the absorbent article.

In the case where the final thickness of the overall structure exceeds an acceptable value, the absorbent core 28 may be designed to be thinner in the region of the fecal storage material, or to be free of absorbent core in that region.

In the special case of this design, it is advantageous to further develop the capillary action and to further optimize this action. A particular aspect of the invention is the formation of channels in the faeces storage material. These channels may be created by removing material by conventional means, such as by cutting or mitering (scarf). In this example, the channels are defined by adjacent materials of different thicknesses or basis weights. Alternatively, these channels are created by compacting (embossing) certain areas of the faeces storage material. Thus, the channels are defined by adjacent regions of different density. In addition, the channels may have different thicknesses, basis weights, and densities at the same time.

More preferably, these channels can be generated using the methods described in detail in European patent application 96108394.6 filed on 28.5.1996. This patent application describes a suitable material and preferred procedure for making such material by post-forming a porous web by manipulating two grooved rolls within a high range of precision such that the pores of the web are permanently deformed to some extent, thereby enhancing fluid transport properties.

This configuration allows for the discharged faeces to be distributed, or at least partly, towards the rear of the absorbent article.

Claims (10)

1. A disposable hygiene article comprising:

a liquid pervious first topsheet;

a liquid impervious backsheet joined to said first topsheet at least partially peripherally; and

a fecal storage material positioned between said first topsheet and said backsheet for absorbing low to medium viscosity fecal material characterized by

The material has a fecal storage capacity of at least 20 grams per gram when tested as described for the ability to store medium viscosity fecal material.

2. The disposable article of claim 1 wherein said fecal storage material has a fecal storage capacity of at least 35 grams per gram.

3. The disposable article of claim 1 or 2 wherein said fecal storage material comprises a fibrous structure.

4. The disposable article of claim 3 wherein the fibrous structure has a caliper reduction of no more than 55% when subjected to the rebound test described.

5. The disposable article of claim 3 wherein the fibrous structure comprises channels formed by regions of different thickness or density.

6. The disposable article of any of claims 1 to 4 wherein the fecal storage material is treated by the steps of: placing a mesh having fluid distribution properties between a pair of opposing pressure applicators, wherein the pressure applicators have three-dimensional surfaces that are complementary to each other; placing a portion of the mesh between the opposing pressure applicators, and then engaging the opposing three-dimensional surfaces of the pressure applicators with one another to cause the mesh to progressively elongate in a cross-machine direction such that the mesh is at least partially permanently deformed.

7. A disposable absorbent article according to any of claims 1 to 6, characterized in that said first topsheet and said fecal storage material are joined together over substantially their entire opposing surfaces.

8. A disposable absorbent article according to any of claims 1 to 7, characterized in that the fecal storage material is located only in the rear portion of said absorbent article.

9. A disposable absorbent article according to any one of the preceding claims, further comprising an absorbent core positioned between said fecal storage material and said backsheet.

10. The use of a faecal storage material in a disposable item.