CA2399797A1 - Absorbent articles exhibiting improved buckling and bending softness - Google Patents

Abstract

An absorbent article, in particular a diaper, having a composite comprising a topsheet, a backsheet, and an absorbent structure in between, which upon application of a deformation force first buckles with a certain buckling resistance corresponding to a buckling force, whereby upon further deformati on the buckling deformation mechanism changes to a bending deformation mechanis m with a corresponding lower deformation force.

Description

Absorbent articles exhibiting improved buckling and bending softness FIELD OF THE INVENTION
The present invention relates to absorbent articles, such as baby diapers, training pants, adult incontinence articles, feminine protection articles and the like. Iri particular, the present invention relates to such articles, which are comfortable to the wearer by being designed to exhibit a particular softness, and even more so to such articles exhibiting a high liquid handling capability.
BACKGROUND
2o Infants and other incontinent individuals wear absorbent articles such as diapers to absorb and retain urine and other body exudates. Absorbent articles function both to contain the discharged materials and to isolate these materials from the body of the wearer and from the wearer's garments and bed clothing. Disposable absorbent articles having many different basic designs are known in the art. For example, U.S.
Patent Re.
2s 26,152, entitled "Disposable Diaper" issued to Duncan and Baker on January 31, 1967, describes a disposable diaper which has achieved wide acceptance and commercial success. U.S. Patent 3,860,003, entitled "Contractable Side Portions For Disposable Diaper", issued ,to Buell on January 14, 1975, describes an elastic leg cuff disposable diaper which has achieved wide acceptance and commercial success.
so In addition to the containment and isolation requirement, it has been widely recognized, that comfort for the wearer is an important aspect for designing such articles. Whilst many approaches ark known for articles like pantiliner or catamenial pads, such as disclosed in US-A-4.950.264 (Osborne et al.), designs for articles requiring higher liquid handling performance such as diapers for babies or incontinent adults had been typically relatively wide and bulky, when dry and particularly when wet, in the region of the article that fits between the legs of the wearer. An attempt to improve on the comfort of the wearer in these cases has been described in U.S. Patent 4,610,678 (Weisman et al.). In s U.S. Patent No. 5,098,423 to Pieniak et al., a low dry bulk disposable diaper is described, focusing on a relatively low cross sectional area, when dry, particularly in the "impact zone" (defined in the patent as the second and third fifths of the article's length, i.e.
generally in the crotch region of the wearer). The primary approach is to distribute the absorbent material in this impact zone over a wider area, which during use can bunch by ~o being pressed between the legs of the wearer.
Yet further art focuses on providing high performing absorbent articles, with a narrow crotch, low thickness and high liquid handling performance, see for example PCT
publication WO 98/43580. The strict liquid handling performance requirements for such articles may result in structures that are made of potentially stiffer materials, or 1s composites comprising relatively soft materials, which in turn lose a lot of the softness by being combined so as to form laminates or laminate type structures. Such elements, however, often exhibit a significantly increased stiffness - such as well known e.g. from so-called "sandwich" structures used as reinforcement elements or from cardboard corrugating.
2o Thus, whilst several attempts have been made to improve the softness of high liquid handling performance absorbent articles, there is still the need to improve the comfort of the wearer without compromising the exudate handling performance of the article.
SUMMARY OF THE INVENTION
2s The present invention is a disposable absorbent article having a crotch region for being positioned between the legs of the wearer during its intended use, and at least an end region, which comprises a composite made of a topsheet, a backsheet bonded to the topsheet, and an absorbent structure therebetween, which extends at least in to parts of said crotch and end regions. In particular, this composite exhibits for the crotch and 3o end regions a bulk softness force {BS) versus displacement {s} relationship for a displacement, which can be expressed as a mathematical curve, for which a derivative can be determined (d(BS)/ds)=(BS'), which for these composites has at least in one of the regions a displacement value (so) for which the derivative of the curve has a value of zero. Then, for this displacement value (so) the composite exhibits a bulk softness force value (BS{s°}) of less than 10 N, preferably of less than 7.5 new and even more preferably of less tyhan 5 N.
Preferably, the bulk softness in the crotch region is lower than in an end region, and is there preferably less than 5 N, or more preferably less than 3 N.
s In preferred embodiments of the absorbent structure, this includes a wicking layer, which has a Bulk softness value of less than 3 N, preferably less than 1 N. This wicking layer can be a fibrous web, which is treated by a post-formation activation treatment, preferably by a double pass treatment. The absorbent structure can also have an acquisition layer, which has a Bulk softness value of less than 3 N, preferably less than 1 ~o N.
The absorbent structure can comprise a furthere layered absorbent composite, such as with a support layer, and particles which are capable of absorbing liquids, such as superabsorbent gelling polymers, polymeric foam materials, and combinations thereof, which can be joined to said support layer.
~s This layered absorbent composite can be discontinuous, having at least two regions, which are spaced apart longitudinally, preferably such that at least one of these regions extends into an end region, preferably the rear region, of said article.
The support layer for the layered absorbent composite can comprise tissue, non-woven, woven or foam structures, to which the particles can be joined by a joining means, such 2o as melt blown hot melt adhesive. The layered absorbent composite comprises immobilized particles, preferably the particles are immobilized to an extent of at least about 80% on a dry weight basis. preferably of at least about 95%.
The particle basis weight can be greater than about 100 g/m2, preferably greater than about 300 g/m2, more preferably greater than about 500 g/m2. The absorbent structure 25 can be designed to provide an absorbent capacity, such that said crotch region has an ultimate absorbent capacity, which less than about 55% of the total ultimate absorbent capacity of said absorbent structure. The absorbent structure can also be designed to provide an ultimate absorbent capacity of said absorbent structure, which is positioned rearwardly of the crotch point is greater than about 60% of the total article's ultimate so storage capacity.
In a particular aspect of the present invention, an absorbent article with an absorbent structure, which has a front and a rear waist end edge having a front and rear waist end edge width; can have two central regions aligned on either side of the longitudinal centerline of the article, and two lateral side regions positioned laterally outwardly of said respective center regions of said absorbent structure, each of the lateral side regions extending at a width of to 25% of the widest portion of the absorbent structure, outwardly s from the center regions. This absorbent structure further has at least two layers of absorbent material which are in a contacting relationship, thus defining a common contacting surface area, whereby these two layers are bonded to each other by a bonding means, such as a hot melt adhesive, covering a bonding means area, which is less than the common contacting surface area, such that at least 75% of the bonding ~o means area is located within the center core region.
DESCRIPTION OF THE DRAWINGS
Fig. 1 - Absorbent article.
Fig 2 - Schematic description of crotch point definition.
Fig. 3 to 5 - Absorbent cores useful for the present invention.
Fig. 6 - Bulk softness method/clamps drawings.
Fig.7 - Typical curve resulting from Bulk Softness test.
DETAILED DESCRIPTION OF THE INVENTION
2o General definitions As used herein, the term "absorbent article" refers to devices which absorb and contain body exudates, and, more specifically, refers to devices which are placed against or in proximity to the body of the wearer to absorb and contain the various exudates discharged from the body. Absorbent articles include devices designed to absorb urine, 25 which are used by incontinent persons. Such incontinent articles include but are not limited to articles designed for receiving large amounts of liquid at relatively high gush rates, such as diapers, adult incontinent briefs, training pants, diaper holders and liners.
The term "disposable" is used herein to describe absorbent articles which are not intended to be laundered or otherwise restored or reused as an absorbent article (i.e., so they are intended to be discarded after a single use and, preferably, to be recycled, composted or otherwise disposed of in an environmentally compatible manner). A
"unitary" absorbent article refers to absorbent article which is formed of separate parts united together to form a coordinated entity so that they do not require separate manipulative parts like a separate holder and liner.

As used herein, the term "absorbent core" refers to the portions (e.g., layers) of an absorbent article whose function are to acquire, distribute, transfer, store and/or redistribute fluid. Acquisition materials include materials whose primary function is to acquire and then relinquish fluids. Such materials include acquisition layers, topsheet 5 materials, transfer layers, flow control modules, wrap tissues or nonwoven sheets designed to prevent migration of hydrogel forming polymers, etc. As used herein, the term "distribution material" refers to the absorbent core materials) whose primary function is to absorb and distribute/redistribute fluid to points away from the point of initial fluid loading. As used herein, the term "storage material" refers to the absorbent core ~o material that retains the majority of the fluid absorbed by the article. It should be understood that the terms "distribution material" and "storage material" are not mutually exclusive. In certain embodiments, a single material may function to provide both fluid distribution and fluid storage.
As used herein, the term "front" refers to the portion of an article or absorbent core that is intended to be positioned proximate the front of a wearer. The term "rear"
refers to the portion of an article or absorbent core that is intended to be positioned proximate the back of the wearer. As such, use of the relative term "in front of means a position in the article or core more toward the front of the article or core, while the term "behind" means 2o a position in the article or core more toward the rear of the article or core.
As used herein, the term "z-dimension" refers to the dimension orthogonal to the length and width of the member, core or article. The z-dimension corresponds generally to the thickness of the member, core or article.
As used herein, the term "x-y dimension" refers to the plane orthogonal to the thickness of the member, core or article. The x- and y-dimensions correspond generally to the width and length, respectively, of the member, core or article.
so The "crotch point" of an article and the article's absorbent core is determined by placing the article on a wearer then placing the wearer in a standing position and then placing an extensible filament around the legs in a figure eight configuration. (See Figure 2.) The point in the article and the absorbent core corresponding to the point of intersection of the filament is deemed to be the crotch point of the article and the absorbent core. It is understood that the crotch point is determined by placing the absorbent article on a wearer in the intended manner and determining where the crossed filament would contact the article and the absorbent core.
a As referred to herein, the "crotch region" of an absorbent core corresponds to 50% of the absorbent core's total length (i.e., in the y-dimension), where the crotch point is located in the longitudinal center of the crotch region. That is, the crotch region is determined by first locating the crotch point of the absorbent core, and then measuring forward and backward a distance of 25% of the core's total length.
~o As used herein, the term "crotch width" refers to the width in the crotch region of the absorbent core that is the narrowest when measured at the crotch point. When this layer consists of a plurality of discrete layers, the layer having the smallest width is the width of that layer, and therefore is the crotch width of the absorbent core. If a layer is profiled in ~5 the cross (x-) dimension, the width of the layer is determined by the width of the highest basis weight region of the profile.
As used herein, the term "layers" refers to identifiable components of the absorbent structure, and any structure referred to as a "layer" may actually comprise a laminate or zo combination of several sheets or webs of the requisite type of materials as hereinafter described. As used herein, the term "layer" includes the terms "layers" and "layered."
For purposes of this invention, it should also be understood that the term "upper" refers to the layer of the absorbent core which is nearest to and faces the article topsheet;
conversely, the term "lower" refers to the layer of the absorbent core which is nearest to 2s and faces the article backsheet. It should be noted that the various members, layers, and structures of absorbent articles according to the present invention may or may not be generally planar in nature, and may be shaped or profiled in any desired configuration.
Whilst the above describes a segmentation of various regions of the article along the longitudinal center line of the article, a further separation can be done along the lateral so center line. Thereby, the region next to the longitudinal centerline is referred to as the "center region", whilst the region outboard of this region (i.e. towards the lateral edges of the article) are referred to as "lateral side regions".

An exemplary embodiment of an absorbent article according to the present invention is in the form of a diaper 20 having an absorbent core according is shown in Figure 1. Figure 1 is a top plan view of diaper 20 in a flat-out, uncontracted state (i.e., with any elastic-induced contraction removed) having a topsheet 22, a backsheet 24, and an absorbent s core indicated generally as 28 that is positioned between topsheet 22 and backsheet 24.
Topsheet 22 is shown as being transparent so as to better illustrate the absorbent core 28.
As is also shown in Figure 1, diaper 20 has a front waistband region 32, a back ~o waistband region 34, a crotch region 36 and a periphery 38 that is defined by the outer edge of backsheet 24 and which has longitudinal edges designated 40 and end edges designated as 42. The longitudinal axis of diaper 20 runs essentially parallel to longitudinal edges 40 and is depicted as longitudinal centerline 67 (and corresponds to the y-direction or length), while the transverse axis runs essentially parallel to end edges ~5 42 and is depicted as transverse centerline 66 (and corresponds to the x-direction or width). The waistband regions 32 and 34 comprise those upper portions of the diaper 20, which when worn, encircle the waist of the wearer. The article crotch region 36 is that portion of the diaper 20 between waistband regions 32 and 34, and comprises that portion of the diaper 20 which when worn, is positioned between the legs of the wearer 2o and covers the lower torso of the wearer. Thus, the crotch region 36 defines the area of typical liquid deposition for a diaper 20 or other disposable absorbent article.
Topsheet 22 and backsheet 24 can be associated together preferably in the periphery only. As used herein, the term "associated" encompasses configurations where topsheet 2s 22 is directly joined to backsheet 24 by affixing the topsheet directly to the backsheet, and configurations where the topsheet is indirectly joined to the backsheet by affixing the topsheet to intermediate members which in turn are affixed to the backsheet.
Preferably, the topsheet 22 and backsheet 24 are affixed directly to each other by attachment means (not shown) such as an adhesive or any other attachment means as known in the art. As so shown in Figure 1, topsheet 22 has a slightly smaller size configuration than backsheet 24. However, topsheet 22 and backsheet 24 can both have the same size configuration (i.e., are coextensive) to be joined together at periphery 38 of diaper 20.
The size of the backsheet 24 is dictated in part by the size of the absorbent core 28 and the exact diaper design selected. In the embodiment shown in Figure 1, the backsheet 24 has an hourglass-shaped configuration. However, other configuration such as rectangular, I-shaped and the like are also suitable.
Although not shown, diaper 20 can have elastic members that exert a contracting force s on the diaper so that it configures more closely and more comfortably to the wearer.
These elastic members can be assembled in a variety of well known configurations, such as those described generally in U.S. Patent 3,860,003 (Buell), issued January 14, 1975, which patent is incorporated by reference. The elastic members can be disposed adjacent the periphery 38 of the diaper 20, preferably along each longitudinal edge 40, ~o so that the elastic members tend to draw and hold the diaper 20 against the legs of the wearer. Alternatively, the elastic members can be disposed adjacent either or both of the end edges 42 of diaper 20 to provide a waistband as well as or rather than leg cuffs.
See, for example, U.S. Patent 4,515,595 (Kievit et al.), issued May 7, 1985, which is incorporated by reference. The elastic members are secured to the diaper 20 in an ~5 elastically contractible condition so that in a normally unrestrained configuration, these elastic members effectively contract or gather the diaper 20. The elastic members can be secured in an elastically contractible condition in at least two ways. For example, the elastic members can be stretched and secured while the diaper 20 is in an uncontracted condition. Alternatively, the diaper 20 can be contracted, for example, by pleating, and 2o the elastic members secured and connected to the diaper 20 while they are in their unrelaxed or unstretched condition. The elastic members can extend essentially the entire length of the diaper 20 in the crotch region 36, or alternatively can extend the entire length of the diaper 20, or any other length suitable to provide an elastically contractible line. The length of these elastic members is typically dictated by the diaper's 2s design.
Referring to Figure 1, absorbent core 28 is depicted in an "I" configuration.
As is indicated above, the absorbent core 28 will comprise front and rear regions (52, 54), as well as a core crotch region (56). These regions are defined by determining the crotch so point of core 28 in accordance with the description herein. As discussed above, the crotch point is determined by reference to the wearer's anatomy. For purposes of illustration only, the crotch point of core 28 is depicted as item 27 in Figure 1. Crotch point 27 is depicted as being located on the longitudinal centerline 67 of diaper 20 and absorbent core 28. This will generally be the case, regardless of the configuration of the diaper and absorbent core.
However, as indicated, crotch point 27 is not located on transverse centerline 66 in this particular embodiment, though it may be in other diaper/core designs. As is discussed above, once the crotch point 27 of absorbent core 28 is determined, the crotch region 56 is determined by measuring forward from the crotch point a distance of 25% of the core's total length (depicted as transverse line 61 ) and backward from the crotch point a distance of 25% of the core's total length (depicted as transverse line 63).
In this 1o illustration, the crotch region is the region of the core located between transverse lines 61 and 63. As depicted in Figure 1, absorbent core 28 is shown to have a front region 52, a back region 54, and a crotch region 56. Again, the crotch region 56 of core 28 is dictated by the location of the crotch point in the core. The crotch region of the core can be used to define the corresponding crotch region of the article.
The topsheet 22 is preferably compliant, soft feeling, and non-irritating to the wearer's skin. Further, the topsheet is liquid pervious permitting liquids (e.g., urine) to readily penetrate through its thickness. A suitable topsheet may be manufactured from a wide range of materials, such as porous foams; reticulated foams; apertured plastic films; or 2o woven or nonwoven webs of natural fibers (e.g., wood or cotton fibers), synthetic fibers (e.g., polyester or polypropylene fibers), or a combination of natural and synthetic fibers.
The topsheet can be made of a hydrophobic material to isolate the wearer's skin from liquids contained in the absorbent core that is treated on at least one side with a surfactant to allow liquids to readily penetrate through its thickness.
At least a portion of the topsheet can be subjected to mechanical stretching in order to provide a "zero strain" stretch laminate that forms the elastic side panels.
To achieve this, the topsheet is preferably elongatable, most preferably drawable, but not necessarily elastomeric, so that the topsheet will, upon mechanical stretching, be at least to a degree so permanently elongated such that it will not fully return to its original configuration. The topsheet can be subjected to mechanical stretching without undue rupturing or tearing of the topsheet, for which it is preferred that the topsheet have a low cross-machine direction (lateral direction) yield strength.

There are a number of manufacturing techniques which may be used to manufacture the topsheet. For example, the topsheet may be a nonwoven web of fibers. When the topsheet comprises a nonwoven web, the web may be spunbonded, carded, wet laid, meltblown, hydroentangled, combinations of the above, or the like. A preferred topsheet 5 is carded and thermally bonded by means well known to those skilled in the fabrics art. A
preferred topsheet comprises staple length polypropylene fibers having a denier of about 2.2. As used herein, the term "staple length fibers" refers to those fibers having a length of at least about 15.9 mm (0.625 in). Preferably, the topsheet has a basis weight from about 18 to about 25 g/mz. A suitable topsheet is manufactured by Veratec, Inc., a ~o division of International Paper Company, of Walpole, Massachusetts, under the designation P-8.
The topsheet 22 is positioned above the body surface of the absorbent core 28.
In preferred embodiments, an acquisition material is positioned between absorbent core 28 ~5 and topsheet 22. Topsheet 22 can be joined to the absorbent core 28 and/or backsheet 24 by attachment means (not shown) discussed herein. Suitable attachment means are described below with respect to joining the topsheet 22 and/or backsheet 24 to the absorbent core 28. As used herein, the term "joined" encompasses configurations whereby an element is directly secured to the other element by affixing the element 2o directly to the other element, and configurations whereby the element is indirectly secured to the other element by affixing the element to intermediate members) which in turn are affixed to the other element. -In a preferred embodiment of the present invention, the topsheet and the backsheet are joined directly to each other in the diaper periphery and can be indirectly joined together according to the teachings as discussed herein.
The topsheet can comprise a structured carrier material as disclosed in PCT
Publication WO 99/25288 (Roe), the disclosure of which is incorporated herein by reference. The structured carrier is compliant, soft feeling, and non-irritating to the wearer's skin.
Further, the structured carrier is liquid pervious, permitting liquids (e.g., urine) to readily so penetrate through its thickness. A suitable structured carrier may be manufactured from a wide range of materials, 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 combination of natural and synthetic fibers. Preferably, the structured carrier is made of a hydrophobic material to isolate the wearer's skin from liquids contained in the absorbent core. Alternatively, the structured carrier may be surfactant treated to make it hydrophilic.
The structured carrier preferably has a plurality of apertures with an effective aperture size of at least 0.2 square millimeters, more preferably, the plurality of apertures have an effective aperture size of at least 0.5 square millimeters, even more preferably, the plurality of apertures have an effective aperture size of at least 1.0 square millimeters, and most preferably, the plurality of apertures have an effective aperture size of at least 2.0 square millimeters. Effective apertures are those which have a gray level of 18 or ~o less on a standard gray level scale of 0-255, under the image acquisition parameters described in the referred PCT publication WO 99/25288.
The structured carrier preferably has an effective open area of at least 15 percent, more preferably the structured carrier has an effective open area of at least 20 percent, even more preferably, the structured carrier has an effective open area of at least 25 percent, and most preferably the structured carrier has an effective open area of at least 30 percent. Carriers thusly constructed are particularly effective in receiving fecal matter, and provide a trans-topsheet capacity of at least 0.2g/in2 (1.3 g/cm2) when submitted to the Trans Topsheet Capacity test as described in EP-A-0,706,546, which is incorporated 2o herein by reference.
The backsheet 24 is substantially impervious to liquids (e.g., urine) and is preferably manufactured from a thin plastic film, although other flexible liquid impervious materials may also be used. As used herein, the term "flexible" refers to materials which are Zs compliant and will readily conform to the general shape and contours of the wearer. The backsheet is intended to prevent the exudates absorbed and contained in the absorbent core from wetting articles which contact the diaper such as bed sheets and undergarments. The backsheet may thus comprise a woven or nonwoven material, polymeric films such as thermoplastic films of polyethylene or polypropylene, or 3o composite materials such as a film-coated nonwoven material. Preferably, the backsheet is a thermoplastic film having a thickness of from about 0.012 mm (0.5 mils) to about 0.051 mm (2.0 mils).

In a particular embodiment of the present invention, at least a portion of the backsheet is subjected to mechanical stretching in order to provide both a "zero strain"
stretch laminate that forms the elastic side panels and, if desired, to prestrain the portion of the backsheet coinciding with the elastic waist feature or any other elastic feature. For this, the backsheet is preferably elongatable, most preferably drawable, but not necessarily elastomeric, so that the backsheet will, upon mechanical stretching, be at least to a degree permanently elongated such that it will not fully return to its original undistorted configuration. In preferred embodiments, the backsheet can be subjected to mechanical stretching without undue rupturing or tearing. Therefore, it is preferred that the ~o backsheet have an ultimate elongation to break of at least about 400% to about 700% in the cross-machine direction as measured using a method consistent with ASTM D-638.
Thus, preferred polymeric films for use as such a backsheet contain a high content of linear low density polyethylene. Particularly preferred materials for the backsheet include blends comprised of about 45-90% linear low density polyethylene and about 10-55%
~s polypropylene. Exemplary films for use as the backsheet of the present invention are manufactured by Tredegar Industries, Inc. of Terre Haute, Indiana under the designations X-8323, RR8220 blend for certain blown films, and RR5475 blend for certain cast films.
2o The backsheet 24 can be embossed (typically, to a caliper of about 0.127 mm (5.5 mils)) and/or matte finished to provide a more clothlike appearance. Further, the backsheet may permit vapors to escape from the absorbent core (i.e., breathable) while still preventing exudates from passing through the backsheet. Examples of vapor permeable backsheet materials include microporous films, such as available from Exxon Chemical, 2s Texas, US, under the designation EXXAIRE ~ or laminates, monolithic films, such as available from Elf AtoChem under the designation PEEBAX ~, or from DuPont under the designation HYTREL ~, or from BF Goodrich under the designation ESTANE ~, or laminates and nonwoven laminate structures.
so The backsheet 24 is positioned adjacent the lower surface of the absorbent core 28.
Alternatively, an additional material (e.g., an additional acquisition material) may be placed between the backsheet 24 and the absorbent core 28. The backsheet 24 may be secured to the absorbent core 28 or any intervening material by adhesive, preferably in a pattern as described hereinafter. Alternatively, the attachment means may comprise heat bonds, pressure bonds, ultrasonic bonds, dynamic mechanical bonds, or any other suitable attachment means or combinations of these attachment means as are known in the art.
s The absorbent core 28 can comprise any absorbent material which is capable of acquiring, distributing and/or retaining liquids such as urine and other certain body exudates, and which is capable of providing good liquid handling capability, generally expressed in terms of good acquisition, distribution and storage, in particular for urine, under conditions such as delivery rate, or volume as typical for babies or adults.
~o Such a performance can be assessed by methods well known in the art, such as the curved acquisition test and/or the rewet test as described in PCT application attorney docket number CM-2060), which is expressly incorporated herein by reference.
According to this disclosure, and to the test methods as described therein, preferred absorbent articles exhibit an absorbent capacity as determined by the Whole Article 15 Vertical Wicking test, wherein capacities are determined for segments of the article positioned in vertical distance away from the folding line of the article, and wherein the absorbent capacity for a segment at 13.5 cm is at least 0.5 times the capacity for the segment at 0 cm, preferably at least 0.75 times, more preferably 1.25, and most preferably at least two times.
zo Suitable absorbent articles can also be described by respective calipers at the crotch, namely by the Saturated Crotch Caliper (SCC), and the Actual Wet Crotch Caliper (AWCC), which are determined following the Curved Acquisition test method, whereby the Actual Wet Crotch Caliper is less than the Saturated Crotch Caliper, The article preferably provides a good rewet performance by exhibiting a Post 2s Curved Acquisition Rewet Value of less than about 180 mg, preferably of less than 150 mg, more preferably of less than 90 mg.
A suitable absorbent article can also be described by comprising an absorbent core, whereby the Actual Wet Crotch Caliper as determined following the Curved Acquisition test method at the crotch point, is less than the Actual Wet Waist Caliper, as so determined following the Curved Acquisition test method at a waist point, and the article provides for a good rewet performance by exhibiting a Post Curved Acquisition Rewet Value of less than about 180 mg.
As in a preferred design the liquid storage region is located remote from the liquid loading zone, the absorbent articles, or components thereof, exhibit a good liquid distribution s functionality such as described in detail in PCT publication 98/43580, which is expressly incorporated herein. According to the teaching, an absorbent article comprises an absorbent core with a crotch region and at least one waist region, whereby said crotch region has a lower ultimate fluid storage capability than said at least one waist region, whereby the crotch region further comprises a high flux liquid distribution material having ~o a flux at 12.4 cm of more than 0.075 g/cm2/sec, according to the Vertical Wicking Test as described in detail therein.
While absorbent core 28 is depicted in Figure 1 in an "I" configuration, any shape may be utilized. For example, an absorbent core 128 is shown in Figure 3 in an "hour glass"
configuration, wherein the core has arcuate cutouts in its longitudinal edges, indicated generally as 142. For illustration purposes, the crotch point is identified by item 127. (As discussed above, the crotch point of the absorbent core is extrapolated from the wearer.) As shown, the crotch point 127 generally lies on longitudinal center line 167 and on transverse line (though not the center transverse line in this embodiment) 168. The Zo crotch region is determined by measuring forward from the crotch point a distance of 25% of the core's total length (depicted as transverse line 161 ) and backward from the crotch point a distance of 25% of the core's total length (depicted as transverse line 163).
The crotch region 156, is the region of the core between transverse lines 161 and 163.
is In addition to crotch region 156, core 128 has a front region 152 and a rear region 154.
The crotch width of the absorbent core at the crotch point, when dry and when wet, is important in providing improved fit on the wearer. It is preferred that the crotch width be small, even when wetted with fluid, so that the absorbent core undergoes minimal bunching when the wearer's legs are closed. In this regard, the absorbent cores useful in ao the present invention will have a crotch width when dry and optionally when wet of not more than about 9 cm. Preferably, the crotch width when dry and preferably also when wet will be not more than about 7 cm, still more preferably not more than about 5 cm, and yet more preferably less than 3 cm. Wet crotch width can be measured following the Curved Acquisition test described hereinafter. As it pertains to the issue of bunching during wear, crotch width may be more relevant than cross sectional area at the core's crotch point. Also in this context, the narrowest dimension in the transverse dimension is considered to be the crotch width layer.

It follows that a reduction in the crotch width of an absorbent core with a uniform capacity per unit surface area necessarily reduces the amount of material and capacity in the liquid deposition zone. Prior attempts to improve fit by reducing width in the crotch region did so by increasing capacity per unit surface area so as to maintain the necessary ~o capacity in the crotch region. Such prior attempts utilized additional fiber in the crotch region for liquid absorption and in some instances additional hydrogel-forming polymers for liquid storage. These approaches therefore result in thicker absorbent cores, particularly in the crotch region, which in turn have a negative impact on bulk both dry and wet. In direct contrast, the present invention is intended to move the fluid deposited ~5 in the crotch region away from that region. This is reflected in the reduced level of fluid storage in the crotch region of the absorbent core. As such, in a preferred embodiment of the present invention, the crotch region of the absorbent core will comprise materials) that function to distribute fluids away from the crotch region. While fluid distribution is an important function of the core's crotch region material, it is within the scope of the 2o invention to include materials in the crotch region whose primary function is the storage of fluids, so long as the requisite level of storage in the crotch region is not exceeded.

One particular aspect of the design of hygienic articles are the contradicting requirements for functionality and comfort. Hence, low capacity articles - such as so-called "panty liner"
- can be designed much easier with a desired level of softness than articles exhibiting s high absorbent capacity, such as baby diapers, or adult incontinence articles. Similarly, articles wherein materials are used, which exhibit particularly good liquid transport and liquid retention properties even under in-use conditions such as increased pressures, often achieve this via increased inherent stiffness.
The concept of "softness" is a well known desideratum for hygiene applications, and ~o there are various approaches to assess the subjective softness of given materials and resultant comfort of a wearer, by physical characteristics. Most of these are linked to particular deformation characteristics of specific individual materials rather than the whole article itself.
Thus, for a number of applications, softness of an article can be assessed for and ~s achieved by a low caliper of the article and/or the liquid handling components used therein, but not for articles having an increased caliper such as for more stringent liquid handling requirements.
Consequently, a major focus of previous developments has been to ensure that such 2o materials exhibit a good softness, and it has been well established in the art, that there are various mechanical mechanisms which impact on the softness impression.
The objective evaluation of the fabric quality was conducted/measured on the Kawabata Evaluation System for Fabrics (KESF). There is available commercially an integrated system for the measurement of fabric mechanical and surface properties. This equipment 2s is designed to measure low stress tensile, bending, shear and lateral compression properties of fabrics, as well as fabric surface friction and surface topography (Reference: S. Kawabata, "The Standardization and Analysis of Hand Evaluation, 2nd Edition." The Textile Machinery Society of Japan, 1980). A series of expressions are developed which relate the components of fabric handle called the "Primary Hand Values 30 (PHV)" (stiffness, crispness, anti-drape, smoothness, and fullness) and fabric mechanical and surface properties. Expressions are also developed for the overall fabric handle rating called the "Total Hand Value" (THV) from the Primary Hand Values. The KESF
data is used for analysis of fabrics.

Whether these tests are fully reflective of all aspects of softness is open to debate. The Kawabata series does, however, have limitations of material thickness which can prevent measurements of many types of articles related to the present invention. In view of such complexity, namely these 17 parameters, many researchers focus~n a few of these parameters, either according to the protocol described therein or by a different protocol addressing the same of a similar property. Thus, one important property that has been identified is the bending resistance, such as measured in TABER stiffness (see TAPPI
test method, T489 om-92, revised 1992), or GURLEY stiffness tests (see TAPPI
test method 543), both of which test methods are originally designed for paper sheets, which ~o were then re-applied for thin and flexible materials, such as fabrics, and hence have significant undesired limitations with respect to sample thickness.
Whilst such tests can be useful to varying degrees for assessing various individual materials, they are significantly limited in the maximum thickness of a material or consequently of articles that comprise thicker materials.
~s In order to better describe materials or composites for being used in absorbent articles, which may have thicker caliper, but still provide comfortable softness during use, the "buckling/bending" test has been found to be particularly useful. This test combines the most relevant parameters and properties of complete article sections thereby allowing an assessment of the article or composite softness versus softness of the individual 2o materials. This approach takes into account all aspects of the articles structure and is therefore particularly suitable for high liquid handling performance articles.
The key elements of this test are "buckling resistance" and the (subsequent) bending deformation.
Accordingly, a comfortable article should exhibit a certain resistance to a lateral 2s compression deformation of resistance to buckling in order to avoid excessive bunching of the article.
Bunching is generally referred to as the mechanism of deformation, where the article is deformed during use in an uncontrolled fashion, thereby forming a rope-like structure, with arbitrary shape, excessive caliper or thickness and deteriorated performance. In so contrast, the desired mechanism is to deform the article towards an upwardly (i.e.
towards the wearer) concavely shaped curve.
Once the article has resisted the bunching deformation to a certain extent via controlled buckling, it can then further deform in a controlled manner by further bending the arcuately deformed buckle. During this bending phase, the material deformation defines the shape of the curve which initially exhibits a reduction in forces. Thus, for subsequent deformation, the force required to deform the article after the initial shaping of the buckle will be less than for the initial buckle shaping. Hence, the article can withstand the lateral forces without undue bunching, and it will also reduce the propensity for undesired pressure marks exerted on the body of the wearer..
When applying the "Buckling/bending" test method as described hereinafter in more detail, the result of this test will be a diagram, plotting the deformation /
deflection versus the corresponding force for the given deformation / deflection. This curve will - at least initially have an "upward" trend, i.e. for an increase in deformation the force will increase, ~o too. This can be a "monotonically" increasing curve, i.e., in mathematical terms, an increase in deformation will have a corresponding increase in force. This behavior includes the regular "elastic" region, where upon relief of the force, for example, the deformation will return to the starting point, but also for "plastic deformation, where upon relief of the extending force the original shape will not be resumed.
~s Such a monotonically increasing curve can be observed for conventional articles, in particular when these comprise webs or layers, which are unbonded in themselves (e.g.
fluff pulp), but which are bonded to each other in a layered configuration by conventional gluing techniques.
However, for articles according to the present invention, the curve generated in the zo bending/buckling test exhibits a maximum, i.e. within a certain range of deformation/deflection, an increase in deflection will not result in an increase in required force but rather will result in a reduction of force. In mathematical terms, this maximum can be expressed by the curve having a first derivative of zero for this range - and for deflection force values less than this maximum point, the derivative will be above zero, 25 and for deflection values greater than the maximum point, the derivative will have values less than zero.
In particular, it has been found, that these deformation properties are relevant for the crotch region where the fluid handling mechanisms have to be maintained, as well as for the front or back region, to establish and sustain a good fit.
It should be noted, that even if the individual components of a structure are soft and flexible, and have the described buckling/bending behavior, the combination of these components can result in a significant increase in rigidity, such as most easily can be understood when considering for example corrugated card-board. Therein, the gluing of.

several flexible layers of paper result in a marked increase in stiffness.
Articles according to the present invention should be made of materials or material combinations, which are not excessively "stiff'. This has to be satisfied without compromising on the fluid handling properties.
s Thus, if the article is made out of several materials, each of these materials must individually satisfy the buckling/bending requirements. Thereby such materials can exhibit other desirable properties, such as compression softness (e.g. for certain foams).
Once suitable materials are selected, these have to be arranged so as to not negatively impact softness. This is particularly relevant for the crotch region of the article wherein ~o the need for effective liquid transport together with the desire to deliver low volume of the structure is desired. In addition, this area is highly influenced by movements of the legs and compression forces experienced when the legs are brought together. Given these movements it is preferred that this area exhibit the lowest force from the Buckling /
Bending test relative to at least one of the front or rear article regions.
~s For example, a high flux material may be arranged next to a storage material, provided the other requirements are fulfilled. Further, materials should not be combined in such a way that the combination exhibits unacceptable structural softness.
In particular, it has been found, that the adhesive bonding of various layers (as discussed 2o in more detail hereinafter) can have a major impact on the softness, and may degrade it from initially very soft to very stiff. For the present invention, this relates to the bonding between two or more layers. "Bonding" in the context of the present invention relates to permanent or temporary bonds (i.e./e.g. between manufacturing and first in-use wetting).
A simple way to achieve bonding is to compress two materials to each other, over a large 2s surface, or over parts thereof, such as the form of a pattern. Also, the bonding can be achieved by application of adhesives or glues, also over a large surface area, or over parts thereof.
In one particular aspect of the present invention, the bonding between two layers is designed so as to balance the requirement of good liquid communication between two 3o adjacent surfaces, without creating excessive stiffness, such as by allowing these two surfaces to move relative to each other without excess friction. Hence, this aspect of the present invention relates to particular bonding patterns, as well as to surface properties for areas outside these patterns.

Permanent bonding is commonly achieved by using glues, or adhesives. Also commonly known are application methods for such adhesives, which will result in particular bonding patterns, with the general classification being slot coating, glue bead application as straight beads or as spiral beads, glue spraying resulting in a in a dot like or fiber like 5 appearance.
For all applications, there can be a full coverage of a given surface, or the adhesive can be applied in a patterned fashion.
Within the context of the present description, the term pattern refers to at least two sub regions of this given surface, which can be differentiated by different adhesive ~o application, such as glue coating or not, glue spraying or not, glue bead applications or not, or - instead of having "no glue" - having a distinctively different amount or application type of glue.
Within a sub-region, to which glue has been applied, there can be further sub-region without glue - which can be best exemplified by considering a dot-spray-glue application ~s to a distinct pattern - between adjacent glue dots, there will be a glue free (sub-region), however such a region will be readily discernible from the region without any spray-glue application.
Similarly, parallel, straight glue beads will have a certain glue free stripe between them, however, if two or more beads are arranged close to each other, and in a spaced 2o relationship to a further group of two or more beads, the beads grouped to each other will form one region, and the space between two groups will form the other region.
If glue beads are not executed in a straight application pattern, but - as e.g. will be the case for the well-known "spiral-glue-application" - in a curved, or cycloid pattern (e.g.
generated by rotating nozzle over a moving substrate), the width of this pattern will be defined by the diameter of this rotating movement. In case of two spiral beads arranged next to each other, these can be in an overlapping configuration - thereby defining either one continuous zone with glue, or two glue zones with differing glue levels (where the spiral overlap, and where not) - or the spirals can be spaced apart, with one glue applied region, and one glue free region.
so Adhesives which have been found to be satisfactory ire manufactured by Century Adhesives, Inc. of Columbus, Ohio and marketed as Century 5227; and by H.B.
Fuller Company of St. Paul, Minnesota and marketed as HL-1258.
Then, this particular aspect of the present invention relates to the specific arrangement of such bonding patterns, so as to maintain the softness of a composite as high as possible without compromising on the functional integrity of the article required for fluid handling.
Whilst conventional articles generally shifted the balance towards the integrity and liquid performance, the present invention provides in this particular aspect an article, which is not bonded over the full width, but primarily in the center region, whilst the lateral side s regions are left substantially free of glue, and thus can allow easy relative movement of the two layers, and thus will allow for low bending resistance.
The center region of the absorbent structure or article can be defined by measuring in both directions laterally from the longitudinal center line an amount that is equal to 25%
of the widest portion of the absorbent structure. The remainder of the absorbent structure ~o or article comprises the lateral side portions.
When comprising particulate materials, these should be sufficiently fixed within the structure to prevent dislocation thereof, or losses. Thus, preferably at least 80 %, more preferably more than 95 % of the particles, on a dry weight basis, are retained in a such ~s a structure upon shaking the structure. This can be done manually, such as by shaking it 60 times within 30 seconds, or this can be done by placing a sample of known dimensions, such as 10 cm by 10 cm, and known particle content on a conventional sieve machine, such as Retsch Vibro VS1000, with a vibration height of about 2 mm on a relatively large mesh, such as a 14 mesh with about 1.4 mm openings. The shaken out 2o particles are caught in a suitable pan or plate, and the percentage of retained particles is determined.
A further approach to come to structures or components useful for the present invention is described in PCT publication WO 99/42067 (McFall et al.), describing a method of 2s making a slitted or particulate absorbent material for an absorbent article such as sanitary napkins, diapers, incontinence devices, and the like. This method can be carried out in situ on another component of the absorbent article in a manufacturing process without cutting the other component. In one embodiment, the absorbent material is placed between two carrier webs, and a strain is applied to the composite of the 3o absorbent material and the carrier webs. The strain and resultant force breaks the absorbent material, but only deforms the carrier webs to provide a self-contained web of particulate material between two carrier webs. Absorbent structures formed by this method are also disclosed. In one embodiment, the absorbent structure comprises a composite web of discrete elements of absorbent material. The composite web comprises at least one carrier web and a plurality of discrete elements of absorbent material arranged in an orderly array on the carrier web. In one embodiment, the discrete elements of absorbent material are positioned adjacent to each other without any intervening material between the discrete elements of absorbent material.
s Example 1 This is an absorbent article comprising an absorbent core, schematically depicted in Fig.4, showing a garment side view of such an absorbent core, and Fig. 5 showing a cross sectional view of such an absorbent core. The acquisition layer 701 of example 1 comprises a layer of chemically stiffened cellulosic. The acquisition layer 701 ~o of example 1 has a longitudinal dimension of 260 mm and a transverse dimension of 60 mm. The basis weight of the acquisition layer 701 is 340 gsm resulting in a total weight of approximately 5.3 grams. The acquisition layer 701 is the layer located closest to the wearer oriented surface.
Example 1 further comprises a front storage member 704 located in the front ~s waist region 706 and a rear storage member 708 located in the rear waist region 707. In example 1, the storage members 704 and 708 are located on the backsheet oriented surface of the absorbent core and comprise the same type of material. The storage members 704 and 708 comprise a HIPE based open celled polymeric foam designed for storage of fluid. The front storage member 704 is substantially rectangular in shape, with 2o the exception of the shaped inner edge 710, having a width, transverse dimension, of 130 mm and a length, longitudinal dimension, of 110 mm. The basis weight of the storage member 704 is 160 gsm resulting in an approximate total weight of 2.1 grams.
The rear storage member 708 is substantially rectangular in shape, excepting for the shaped inner edge 710, having a width, transverse dimension, of 130 mm and a length, 25 longitudinal dimension, of 188 mm. The basis weight of the rear storage member 708 is 160 gsm resulting in an approximate total weight of 3.8 grams.
Example 1 further comprises a distribution member 703, which is located on the wearer oriented surface of the front and rear storage members 704 and 708, and on the backsheet oriented surface of the storage/rewet barrier members 705 and 709 .
The so distribution member 703 comprises a post formation treated chemically bonded fibrous web, according to the teaching of examples of EP-A-0.810.078, except that the mechanical post formation treatment was applied twice to said web. The distribution member 703 extends from the front waist region 706 through the crotch region 702 and into the rear waist region 707. The distribution member 703 is slightly shaped having a transverse dimension of 80 mm in the front and rear waist regions 706 and 707 and a s transverse dimension of 60 mm in the crotch region 702. The longitudinal dimension of the distribution member 703 is 438 mm. The basis weight of the distribution member 703 is 120 gsm resulting in an approximate total weight of 3.9 grams.
The distribution member is bonded to the acquisition/distribution layer by conventional adhesives, such as applied by spiral glue applicators in the longitudinal ~o center region only, i.e. without being bonded laterally outside this center region.
Example 1 further comprises storage/rewet barrier members 705 and 709 located on the wearer oriented surface of the distribution member 703 and the front and rear storage members 704 and 708 and on the backsheet oriented surface of the acquisition member 701. The storage/ rewet barrier members 705 and 709 comprise ~s superabsorbent material adhesively bonded to the remaining core structure.
The shape of the storage/rewet barrier members approximate the shape of the storage members 704 and 708. The storage/rewet barrier members 705 and 709 have a basis weight of nominally 300 gsm. This basis weight results in a total weight of 11 grams.
Example 2 2o Example 2 is an absorbent article comprising an absorbent core of the present invention, which is also schematically depicted in Fig.7, showing a garment side view of such an absorbent core, and Fig. 8 showing a cross sectional view of such an absorbent core. The acquisition layer 701 of example 2 comprises a layer of chemically stiffened cellulosic fibers combined with a bicomponent fiber in a ratio of 87% to 13%, respectively.
25 The acquisition layer 701 of example 2 has a longitudinal dimension of 260 mm and a transverse dimension of 60 mm. The basis weight of the acquisition layer 701 is 340 gsm resulting in a total weight of approximately 5.3 grams. The acquisition layer 701 is the layer located closest to the wearer oriented surface.
Example 2 further comprises a front storage member 704 located in the front so waist region 706 and a rear storage member 708 located in the rear waist region 707. In example 2, the storage members 704 and 708 are located on the backsheet oriented surface of the absorbent core and comprise the same type of material. The storage members 704 and 708 comprise a HIPE based open celled polymeric foam designed for storage of fluid. The front storage member 704 is substantially rectangular in shape, with the exception of the shaped inner edge 710 having a width, transverse dimension, of 130 mm and a length, longitudinal dimension, of 110 mm. The basis weight of the storage member 704 is 160 gsm resulting in an approximate total weight of 2.1 grams.
The rear storage member 708 is substantially rectangular in shape, excepting for the shaped inner edge 710 having a width, transverse dimension, of 130 mm and a length, longitudinal ~o dimension, of 188 mm. The basis weight of the rear storage member 708 is 160 gsm resulting in an approximate total weight of 3.8 grams.
Example 2 further comprises a distribution member 703 which is located on the wearer oriented surface of the front and rear storage members 704 and 708 and on the backsheet oriented surface of the storage/rewet barrier members 705 and 709 .
The ~5 distribution member 703 comprises a fibrous structure comprising chemically stiffened, twisted, and curled bulking fibers, high surface area fibers, and chemical binder additive.
The distribution member 703 extends from the front waist region 706 through the crotch region 702 and into the rear waist region 707. The distribution member 703 is slightly shaped having a transverse dimension of 80 mm in the front and rear waist regions 706 2o and 707 and a transverse dimension of 60 mm in the crotch region 702. The longitudinal dimension of the distribution member 703 is 438 mm. The basis weight of the distribution member 703 is 120 gsm resulting in an approximate total weight of 3.9 grams.
The distribution member is bonded to the storage members and barrier members by conventional adhesives, such as applied by spiral glue applicators in the longitudinally Zs center region only, i.e. without being bonded outside this center region.
Example 2 further comprises storage/rewet barrier members 705 and 709 located on the wearer oriented surface of the distribution member 703 and the front and rear storage members 704 and 708 and on the backsheet oriented surface of the acquisition member 701. The storage/ rewet barrier members 705 and 709 comprise 3o superabsorbent material adhesively bonded to the remaining core structure.
The shape of the storage/rewet barrier members approximate the shape of the storage members 704 and 708. The storage/rewet barrier members 705 and 709 have a basis weight of nominally 300 gsm. This basis weight results in a total weight of 11 grams.

Bulk softness method This method is intended to measure individual materials as well as structures comprising these materials. Accordingly, this method can be used to assess regions of an article, such as front, back, or crotch region thereof. The method provides a correlation, such as ~o can be graphically represented as a curve, between a bulk softness (BS) value in units of force [N] (y-axis) vs. displacement in units of length [mm] (s) (x-axis).
Suitable structures or articles according to the present invention will exhibit a smooth, continuous curve over the range of useful extensions, thus allowing determination of the first derivative of that curve (d{BS}/ds), often abbreviated as (BS') (see Fig. 7).
15 The method uses a tensile tester in compressive mode and a sample holder (Figures 6a and 6b) to measure the buckling force for a sample.
Apparatus Tensile Tester: A suitable tensile tester is available from Zwick Company of Ulm, Germany as a Zwick Material Tester type 144560.
2o Sample Holder: The sample holder for this test is shown in Figures 6a and 6b. As can be seen therein the sample is held between two curvilinear (the curvature of the outer element of the holder has a radius of 59 mm~1 mm with an arc length of 150 mm and the inner element has a radius of 54 mm~1 mm with an arc length of 140 mm) plates that have tabs 25 30 mm wide that extend upward 20 mm (front element) and 55 mm (rear element) so as to enable insertion of the sample holder into the jaws of the tensile tester. The equipment is designed to test various material thickness from 1 mm up to 10 mm. As will be recognized, sample holders of this type are necessary for both the upper and lower 3o jaws of the tensile tester.

Sample Preparation Prior to testing a sample is conditioned under controlled conditions (50% RH, 25°C) for at least two hours.
The sample is cut to 60 mm X 150 mm (~2 mm per dimension). The sample dimensions, short side vs. long side, should be consistent with the material orientation when used in a finished product (i.e. if the material in use has a short dimension and a long dimension then the sample should be cut such that the short side of the sample is the same relative side as in the overall material).
~o The crotch region sample should taken from the article along the longitudinal centerline oriented such that 75mm of the length of the sample is toward the front relative to the crotch point and 75mm of the sample is toward the rear. The front and/or rear region samples should be obtained also along the longitudinal centerline with the 150 mm length of the sample being measured along the longitudinal center line from either the front absorbent structure end or the rear absorbent structure end, respectively. The front and rear samples may extend partially into the crotch region of the absorbent structure.
Apparatus Setup 1. Calibrate the tensile tester (in compressive mode) according to the 2o manufacturer's instructions.
2. Set the compression rate to 200 mm/minute. Set the crosshead stop point to mm.
3. Insert a sample into the sample holder to a depth of 7 mm ~1 mm for each clamp set.
2s 4. Set the tensile tester jaw separation so that the unconstrained portion of the sample is smooth and unbuckled. This corresponds to a spacing between the upper and lower portions of the sample holder of 46 mm.
Operation and Data Collection 1. Insert the sample/sample holder assembly into the jaws of the tensile tester.
so 2. Operate the tensile tester in compressive mode to record a force/compression curve for each sample.
3. Record the buckling force for each sample. Buckling force is the force required to cause the sample to initially begin to buckle. It is the initial peak force that is seen on the force compression curve before a relatively constant force plateau that is a measure of the bending resistance of the sample (bending force).
4. Repeat steps 1-3 for at least 5 samples for each structure tested and report the average and standard deviation of the buckling force.
Determination of curve and derivatives Referring to Fig. 7, a typical result for structures and components is shown, wherein, in the region depicted as "A" the buckling mechanism takes place, which changes to a bending mechanism in the region depicted "B" with a reduction if force after the maximum at the transition point from "A" to "B". This transition point 1o also corresponds to the point where the first derivative of the curve is zero.
Crotch point determination Figure 2 illustrates the means for determining the crotch point of an article and its absorbent core. Referring to Figure 2, the legs of a standing wearer are depicted cross ~5 sectionally as 301 and 302. A continuous material 303 (e.g., a string or rubberband) is twisted once and is placed around the wearer's legs at a point sufficiently close the wearer's torso such that the intersection 304 of material 303 can be extrapolated onto the article being worn. The crotch point of the core of the article is thereby determined, and the crotch region of the core is determined per the above description.
2o Further Test Particular reference is made to PCT application IB 99/00741 (internal docket reference CM-2060) in particular with regard to the following methods as described in detail in the test method section thereof:
Synthetic Urine Formulation 2s Curved acquisition Method Post curved acquisition Collagen Rewet Method Absorbent core capacity and absorbent core crotch capacity by Teabag Centrifuge Capacity Test (TCC Test) Caliper Measurement method Capillary Sorption Test Whole Article Vertical Wicking Test Distribution Materials Vertical Wicking Test

Claims (23)

29

1. A disposable absorbent article said article comprising a crotch region for being positioned between the legs of the wearer during its intended use, and at least an end region, said article comprising a first composite comprising a topsheet, a backsheet, and an absorbent structure therebetween, at least in parts of said crotch and end regions, whereby at least said topsheet and said backsheet are bonded to each other, characterized in that said first composite exhibits for said crotch and end regions a bulk softness force {BS} versus displacement {s}, which can be expressed as a mathematical curve, for which a derivative can be determined (d(BS)/ds)=(BS'), whereby for said first composite at least in one of said regions said derivative has at least for one displacement value (s0) a value of zero, and in that for said displacement value (so) the composite exhibits a bulk softness force value (BS{s0}) of less than 10 N, preferably of less than 7.5 new and even more preferably of less tyhan 5 N.

2. An absorbent article according to claim 1, wherein said bulk softness value of said first composite for the displacement values where the derivative of the bulk softness curve equals zero (BS{s0}), is lower in the crotch region than in an end region.

3. An absorbent article according to any of claims 1 or 2, wherein said firstcomposite has a bulk softness value in an end region of less than about 5 N, preferably of less than 3N.

4. An absorbent article according to any of claims 1 to 3, wherein said absorbent structure comprises a wicking layer.

5. An absorbent article according to claim 4, whereby said wicking layer has a Bulk softness value of less than 3N, preferably of less than 1 N.

6. An absorbent article according to claim 4 or 5, wherein said wicking layer is a fibrous web treated by a post-formation activation treatment.

7. An absorbent article according to claim 6, whereby said post-formation activation treatment is a double pass activation.

8. An absorbent article according to any of the preceding claimswherein said absorbent structure comprises an acquisition region.

9. An absorbent article according to claim 8, whereby said acquisition region comprises a material exhibiting a bulk softness value of less than 3 N, preferably of less than 1 N.

10. An absorbent article according to any of the preceding claims, wherein said absorbent structure comprises a second layered absorbent composite, comprising at least one support layer, comprising particles capable of absorbing liquids, joined to said support layer.

11. An absorbent article according to claim 10, wherein said particles are selected from the group of materials consisting of superabsorbent gelling polymers, polymeric foam materials, and combinations thereof.

12. An Absorbent article according to claim 10 or 11, wherein said second layered absorbent composite comprising said particles is discontinuous, having at least two composite regions spaced longitudinally apart.

13. An absorbent article according to any of claims 10 to 12, wherein said second layered absorbent composite comprising said particles is positioned at least one of the end regions of said article.

14. An absorbent article according to any of claims 10 to 13, wherein said second layered absorbent composite comprising said particles is positioned in the rear article region.

15. An absorbent article according to any of claims 10 to 14, wherein said support layer is selected form the group of materials consisting of tissue, non-woven, woven or foam structures.

16. An absorbent article according to any of claims 10 to 15,wherein said particles are joined to said support layer by a joining means.

17. An absorbent article according to claim 16, wherein said joining means is a melt blown hot melt adhesive.

18. An absorbent article according to any of claims 10 to 17, whereby said particles are immobilized to greater than about 80% and dry weight basis, preferably to greater than about 95%..

19. An absorbent article according to any of claims 10 to 18, wherein the particulate basis weight is more than 100 g/m2, preferably more than 300 g/m2, more preferably more than 500 g/m2.

20. Absorbent article according to any of the preceding claims, whereby said absorbent structure provides an absorbent capacity, such that said crotch region has an ultimate absorbent capacity, which less than 55% of the total ultimate absorbent capacity of said absorbent structure,

21. An absorbent article according to any of the preceding claims, whereby said article has a crotch point in said crotch region, and whereby the ultimate absorbent capacity of said absorbent structure positioned rearwardly of said crotch point is greater than about 60% of the article's total ultimate storage capacity.

22. An absorbent article according any of the preceding claims, wherein said absorbent structure has two central regions aligned on either side of the longitudinal centerline of said article, and two lateral side regions positioned laterally outwardly of said respective center regions, each of said lateral side regions extending at a width to 25% of the widest portion of the absorbent structure outwardly from said center regions;
said absorbent structure comprising at least two layers of absorbent material which are in a contacting relationship, thus defining a common contacting surface area;
whereby said two layers are bonded to each other by a bonding means covering a bonding means area, which is less said common contacting surface area, such that at least 75% of said bonding means area is located within the center core region.

23. An absorbent article according to claim 22, wherebysaid bonding means is a hot melt adhesive.