MXPA99008875A - Absorbent articles comprising a material having high flux capabilities - Google Patents

Abstract

Disclosed are absorbent cores for inclusion in articles such as diapers, incontinent briefs, training pants, diaper holders and liners, feminine hygiene garments, and the like, designed to provide improved fit and comfort for the wearer while adequately containing body exudates. The absorbent cores are designed so as to retain low levels of fluid in the crotch region, relative to the other core regions, even when the core absorbs significant amount of fluid during use. To achieve this, the absorbent core is designed such that fluid is moved substantially from the crotch region to the front and/or rear ends of the article. In particular, the absorbent core comprises in its crotch region a distribution material having high fluid flux capabilities even after long periods of time. The material's flux properties reflect its ability to move significant amounts of fluid from the crotch of the core,even after long periods of time (e.g., 10 and 30 minutes).

Description

ABSORBENT ARTICLES THAT COMPRISE A MATERIAL THAT HAVE ELEVATED FLOW CAPACITIES FIELD OF THE INVENTION The present invention relates to absorbent articles such as diapers, incontinence briefs, training pants, diaper bras and liners, sanitary ware garments, and the like, and more particularly, to absorbent articles that provide improved fit when wetted with Bodily fluids. The improved fit is achieved by using an absorbent core material that has high flow capabilities.

BACKGROUND OF THE INVENTION Babies and other incontinent individuals wear absorbent articles such as diapers to absorb and retain urine and other exudates from the body. The absorbent articles work both to contain the discharged materials, and to isolate these materials from the body of the user and the garments and bedding of the users. Disposable absorbent articles having many different basic designs are known in the art. For example, United States Patent Re. 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 No. 3,860,003 entitled "shrinkable side portions for disposable diaper", issued to Buell on January 14, 1975, discloses an elastic fold for the disposable diaper leg which has achieved wide acceptance and commercial success. Many of the diaper designs are relatively broad and bulky, when dry and particularly when wet, in the region of the article that fits between the user's legs. This results in a certain level of discomfort for the user, since these diapers tend to bulge when worn. In an effort to "engage in user discomfort," U.S. Patent No. 4,610,678 (Weismann et al.) Discloses diapers that comprise densified densities that are narrower in this region than were previous designs. even these articles store significant levels of absorbed fluids in the discharge region of the article.This discharge region is placed within the portion of the item that they adjusted in the crotch region of the wearer when it is used.As the previous absorbent articles do not distribute Effectively fluid, these items are typically designed to store significant amounts of fluid within the crotch region of the diaper.Thus, in each load, this region of the article becomes increasingly bulky and therefore tends to to be more uncomfortable by the user See, for example, United States Patent No. 5,098,423 of Pien iak and others, which was formed on the Weismann patent disclosure, and describes a low volume dry disposable diaper. The approach of the patent 5,098,423 is an article having a relatively low cross-sectional area, when dry, particularly in the "impact zone" (defining the patent as the second and third fifths of the length of the article). In fact, an important aspect of the articles described is the ability of the absorbent material in the impact zone to absorb the fluid. The patent specifically states that at least 60% of the total fluid absorbed is retained within the impact zone of the diaper. Therefore, although the patent discusses the desire for improved fit when dry, it fails to address the problem of providing improved fit and comfort throughout the period of use. Moreover, the main consideration for improving the fit is on the thin and wide structures which bend and bulge during use, instead of optimizing the narrowness and the dry and wet volume of the absorbent material in the crotch region. ThereforeArticles described in patent 5,098,423 have an area total low cross section when dry, accomplished by providing a relatively wide relatively thin core (ie, in the Z dimension of the article), (ie, in the X dimension of the article), with 60% of the absorbent capacity in the crotch region. This results in reduced comfort when wetting the item with body fluid. It would therefore be advantageous to provide an absorbent article that provides better fit and comfort to the wearer, even after the article is wetted with body fluids. It would further be advantageous to provide an absorbent article having reduced volume in the crotch region in both dry and wet states. Therefore, it is an object of the present invention to provide an absorbent article providing increased comfort to the user by including in the crotch region of the article a materiai having the ability to move significant amounts of fluid out of the region of Crotch for relatively long periods of time. The inclusion of this material allows the movement of fluid out of the crotch region of the core, thus providing articles that have reduced volume in the crotch region, even when the article is wetted with significant fluid levels. It is a further object of the present invention to provide an absorbent article having improved fit on the wearer during use, by reducing the amount of relative fluid retained in the crotch region of the article. These and other objects of the present invention will be more readily apparent when considered with reference to the following description and when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE INVENTION The present invention provides absorbent articles such as diapers, incontinence briefs, training pants, diaper liners and liners, feminine hygiene garments, and the like, designed to provide improved fit and comfort for the wearer while adequately containing the exudates of the body. This absorbent article has a containment assembly (chassis) comprising an outer cover layer typically comprising a liquid pervious top sheet and a liquid impervious backsheet, and an absorbent core associated with the outer cover layer. The absorbent core is designed to retain low levels of fluid in the crotch region, with relationships to the other regions of the core, even when the core absorbs significant amounts of fluid during use. To achieve this, the absorbent core is designed such that fluid is moved substantially from the crotch region to the front and / or rear regions of the article. In particular, the core comprises a material that is capable of moving relatively large amounts of fluid, even after relatively long periods of time. This ability is reflected in the incremental flow value of the material, which is a measurement of the amount of fluid (synthetic urine) moved from the crotch region (in units of grams) per cm2 (ie, the section area). dry transversal of the material) per minute, in 10 and 30 minute times. The incremental flow is described in detail below, and a method to determine the incremental flow is described in the Test Methods section.

In one aspect, the present invention relates to an absorbent article comprising an absorbent core having a crotch region, wherein (i) the crotch region has an absorbent capacity not greater than about 40% of the total absorbent capacity of the crotch region. absorbent core and (ii) the crotch region comprises a material having an Incremental Flow value in 10 minutes (hereinafter referred to as "IF10 value") of at least about 0.5 g / cm2 / minute. In another aspect of the present invention relates to an absorbent article comprising an absorbent core having a crotch region, wherein (i) the crotch region has an absorbent capacity not greater than about 40% of the total absorbent capacity of the crotch region. absorbent core and (i) the crotch region comprises a material having an Incremental Flow value in 30 minutes (hereinafter referred to as "IF30 value") of at least about 0.3 g / cm2 / minute. In yet another aspect, the invention relates to an absorbent article comprising an absorbent core having a crotch region, wherein (i) the crotch region has an absorbent capacity not greater than about 40% of the total absorbent capacity of the crotch region. absorbent core and (ii) the crotch region comprises a material having an IF10 value of at least about 0.5 g / cm2 / minute and an IF30 value of at least about 0.3 g / cm2 / minute.

BRIEF DESCRIPTION OF THE DRAWINGS Although the description concludes with the claims pointing out in a particular way and claiming differently the exposed matter that is considered as formant of the present invention, it is believed that the invention will be better understood from the following description which is taken in combination with the accompanying drawings, in which they use similar designations to designate substantially identical elements, and in which: Figure 1 is a top plan view of an absorbent article according to the present invention wherein the top sheet is transparent to show more clearly the absorbent core; Figure 2 is a plan view of an absorbent core of the present invention; Figure 3 is a plan view of another absorbent core of the present invention; Figure 4 illustrates how the crotch point of a wearer, an absorbent article and corresponding absorbent core is determined; Figure 5 is an exploded perspective view of a multi-piece absorbent core useful in the present invention; and Figure 6 is a schematic view of the apparatus used to load articles for characterization according to other methods discussed in the Test Methods section.

DETAILED DESCRIPTION OF THE INVENTION As used herein, the term "absorbent article" refers to devices that absorb and contain exudates from the body, and, more specifically, to devices that are placed against or close to the user's body to absorb and contain the various exudates. discharged from the body. Absorbent articles include devices designed to absorb urine, which are used by incontinent people. These incontinence items include but are not limited to diapers, adult incontinence briefs, training pants, bras and diaper liners. Other absorbent articles include those designed to absorb blood-based fluids such as menses. These sanitary ware articles include tampons, catamenial pads, and the like. The term "disposable" is used herein to describe absorbent articles that are not intended to be washed or otherwise restored or reused as an absorbent article (i.e., 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 the absorbent articles which are formed of separate parts joined together to form a coordinated entity such that they do not require separate manipulated parts such as a separate fastener and liner. As used herein, the term "absorbent core" refers to the parts (e.g., layers) of an absorbent article whose function is to acquire, distribute, transfer, store and / or redistribute the fluid. The acquisition materials include the materials whose main function is to acquire, after being stripped of the fluid. These materials include acquisition layers, top sheet materials, transfer layers, flow control modules, tissue or protected wrapping sheets designed to prevent migration of the hydrogel-forming polymers, and so on. As used herein, the term "distribution material" refers to a material an absorbent core materials whose primary function is to absorb and distribute / redistribute the fluid to points away from the point of initial charge of the fluid. As used herein, the term "storage material" refers to the absorbent core material that retains a majority of the retentate fluid, on a weight basis. It should be understood that the terms "distribution material" and "storage material" are not mutually exclusive. In certain embodiments, a simple material may function to provide both fluid distribution and fluid storage.

As used herein, the term "front" refers to the part of an absorbent article or core that is intended to be placed near the front of a user. The term "after" refers to the part of an article an absorbent core that is intended to be placed near the back of the wearer. As such, the use of the relative term "in front of" means a position within the article today core more towards the front of the article or the core, while the term "behind" means a position in the article a more towards the back 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 generally corresponds 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 dimensions X and Y generally correspond to the width and length, respectively, of the member, core or article. The "crotch point" of an article and The absorbent core of the article is determined by placing the article in a user in a standing position and then placing a filament around the legs in a configuration in figure 8. (See Figure 4.) The point in the article and the absorbent core which correspond to the point of intersection of the filament is considered to be the crotch point of the article and of the absorbent core. It should be understood that the crotch point is determined by placing the absorbent article on a user in the manner intended and determining where the cross filament has contact with the article / core. As referred to in this, the "crotch region" of an absorbent core corresponds to 50% of the total length of the absorbent core (ie, in the dimension y), 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 a distance of 25% of the total core length forward or backward. As used herein, the term "crotch width" refers to the width in the crotch region of the absorbent core layer that retains most of the fluid when the article is loaded at 70% of the total capacity of the articles through of the Fluid Acquisition method described below. When these layer consists of a plurality of discrete layers, the layer having the smaller width is the width of that layer, and therefore is the width of the crotch of the absorbent core. If a layer is profiled in the transverse dimension (x), the width of the layer is determined by the width of the region of the highest base weight of the profile. A method for determining the crotch width is described in the Test Methods section below. As used herein, the term "crotch cross-sectional area" refers to the dry cross-sectional area of the crotch region of the absorbent core layer that retains most of the fluid when the article is loaded into the crotch. 70% total absorbent capacity by means of the Fluid Acquisition method described below. When this layer consists of a plurality of discrete layers, the width and gauge of each of the layers is measured and the sum of their individual cross-sectional areas is the cross-sectional area of the crotch region. A method for determining the width of the crotch is described in the Test Methods section below. As used herein, the term "layers" refers to the identifiable components of the absorbent structure, and any structure referred to as a "layers" may actually comprise a laminate or combination of several sheets other than the type of materials required as it is described here later. As used herein, the term "layer" includes the terms "layers" and "in layers." For purposes of the present invention, it is to be understood that the term "upper" refers to the layer of the absorbent core that is closest to and faces the top sheet of the article.; conversely, the term "lower" refers to the absorbent core layer which is closest to and facing the backsheet of the article. It should be noted that the various members, layers, and structures of the absorbent articles according to the present invention may or may not be generally planar in nature, and may be formed or profiled in any desired configuration. One embodiment of an absorbent article in the form of a diaper 20 having an absorbent core according to the present invention is shown in Figure 1. Figure 1 is a top plan view of the diaper 20 in a flattened state, not contracted (i.e., with any contraction induced by the removed elastic) having a top sheet 22, a back sheet 24, and an absorbent core indicated generally as 28 that is positioned between the top sheet 22 and the back sheet 24. The sheet Upper 22 is shown as being transparent to better illustrate absorbent core 28. As also shown in Figure 1, diaper 20 has a front waistband region 32, a waistband region 34, a central region 36 and a periphery 38 that is defined by the outer edge of the backsheet 24 and which has designated longitudinal edges 40 and end edges designated as 42. The longitudinal axis of the diaper 20 runs essentially over parallel to the longitudinal edges 40 and is represented as the longitudinal center line 67 (and corresponds to the Y direction or length), while the transverse axis runs essentially parallel to the end edges 42 and is represented as the transverse centerline 66 (and corresponds to the X or width direction). The waistband regions 32 and 34 comprise those upper portions of the diaper 20, which when worn, surround the wearer's waist. The central region 36 is that part of the diaper 20 between the waistband regions 32 and 34, and comprises that part of the diaper 20 which when worn, is placed between the user's legs and covers the lower torso of the wearer. In this manner, the central region 36 defines the typical liquid deposition area for a diaper 20 or other disposable absorbent article. The top sheet 22 and the back sheet 24 can be mutually associated in any suitable manner. As used herein, the term "associated" encompasses the configurations where the top sheet 22 is attached directly to the back sheet 24 by fixing the top sheet directly to the back sheet, and the configurations where the top sheet is indirectly bonded to the back sheet to fix the upper sheet to intermediate members which in turn are fixed to the back sheet. Preferably, the topsheet 22 and the backsheet 24 are fixed directly together by attachment means (not shown) such as an adhesive and any other bonding means as is known in the art. For example, a uniform, continuous adhesive layer, a patterned adhesive layer, or an array of separate lines or spots of adhesive may be used to secure the top sheet 22 to the back sheet 24. As shown in Figure 1, the top sheet 22 has a slightly smaller size configuration than the back sheet 24. However, the top sheet 22 the sheet being 24 can both have the same size configuration (i.e., be coextensive) such that they join together at the periphery 38 of the diaper 20. The size of the backsheet 24 is dictated in part by the size of the absorbent core 28 and the exact design of the selected diaper. In the embodiment shown in FIG. 1, the backsheet 24 has a configuration in the form of an hourglass. However, other configurations such as rectangular, I-shaped and the like are also suitable. Although not shown, the diaper 20 may have elastic members that exert a contraction force on the diaper in such a way that it configures it more closely and more comfortably to the wearer. These elastic members can be assembled in a variety of well-known configurations, such as those generally described in U.S. Patent No. 3,860,003 (Buell), issued January 14, 1975, whose patents incorporated by reference. The elastic members may be disposed adjacent the periphery 38 of the diaper 20, preferably along each longitudinal edge 40, such that the elastic members will tend to stretch and hold the diaper 20 against the wearer's legs. Alternatively, the elastic members may be disposed adjacent either or both of the end edges 42 of the diaper 20 to provide a waistband as well as instead of the leg cuffs. See, for example, U.S. Patent No. 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 elastically contractible condition such that in a normally unrestricted configuration, these elastic members contract or pick up the diaper 20. The elastic members can be secured in an elastically contractible condition by at least two. ways For example, the elastic members can be pulled and secured while the diaper 20 is in an uncontracted condition. Alternatively, the diaper 20 may be contracted, for example, by pleating, and the elastic members secured and connected to the diaper 20 while in its unrelaxed conditions the unstretched or unstretched ones. The elastic members can extend essentially the total length of the diaper 20 in the central region 36, or alternatively they can extend the total length of the diaper 20, or any other suitable length to provide an elastically contractible elastic line. The length of these elastic members is typically dictated by the design of the diaper. Referring to Figure 1, the absorbent core 28 is represented in an "I" configuration. As indicated above, the absorbent core will comprise front and rear regions, as well as a crotch region. These regions are defined by determining the crotch point of the core 28 according to the description herein. As discussed above, the crotch point is determined with reference to the user's anatomy. For purposes of illustration only, the crotch point of the core 28 is represented as the article 27 in Figure 1. The crotch point 27 is represented as being located on the longitudinal centerline 67 of the diaper 20 and the absorbent core 28. This it will generally be case, without considering the diaper and absorbent core configuration. However, as indicated, the crotch point 27 is not located on the transverse center line 66 in this particular embodiment, although it may be in other diaper / core designs. As discussed above, once the crotch point of the absorbent core 28 is determined, the crotch region is determined by forward measurement of the crotch point at a distance of 25% of the total length of the core (represented as the transverse line 61) and backward from the crotch point at a distance of 25% of the total length of the core (represented as the transverse line 63). In this illustration, the crotch region is the region of the core located between the cross lines 61 and 63. As shown in Figure 1, the absorbent core 28 is shown to have a front region 52, a back region 54, and a crotch region 56. Again, crotch region 56 of core 28 is dictated by the location of the crotch point in the core. The topsheet 22 is docile, soft in feel, and non-irritating to the wearer's skin. In addition, the top sheet is permeable to liquid allowing liquids (eg, urine) to easily penetrate through its thickness. A suitable top sheet can be manufactured from a wide range of materials, such as porous foams; cross-linked foams; plastic films with openings; or woven or non-woven webs of natural fibers (e.g., wood or cotton fibers), synthetic fibers (e.g., polyester or polypropylene fibers), a combination of textile and synthetic fibers. Preferably, the topsheet is made of a hydrophobic material to sweat the skin of the wearer of the liquids contained in the absorbent core which is treated on at least one side with a surfactant to allow liquids to easily penetrate through their thickness. In a preferred embodiment of the present invention, at least a portion of the topsheet is subjected to mechanical stretching in order to provide a stretch laminate with "zero deformation" that forms the side elastic panels. In this way, the upper sheet is preferably stretchable, very preferably stretchable, but not necessarily elastomeric, such that the upper sheet will be, at the time of mechanical stretching, at least permanently elongated to a degree such that it will not fully return to its initial configuration. In preferred embodiments, the topsheet can be subjected to mechanical stretching without undue breaking or tearing of the topsheet. Therefore, it is preferred that the upper sheet have an elastic resistance in the transverse direction (lateral direction) of the low machine. There are a number of manufacturing techniques that can be used to manufacture the top sheet. For example, the top sheet may be a non-woven web of fibers. When the top sheet comprises a non-woven web, the web may be punched, carded, wet-laid, melt-blown, hydroentangled, combinations of the above, or the like. A preferred top sheet is carded and thermally bonded by means well known to those skilled in the art of fabrics. A preferred top sheet comprises polypropylene fibers of cut length having a denier of about 2.2. As used herein, the term "cut length fibers" refers to those fibers having a length of at least about 15.9 millimeters. Preferably, the top sheet has a basis weight of about 18 to about 25 grams / m2. A suitable top sheet is manufactured by Veratec, Inc., a 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 the preferred embodiments, an acquisition material is placed between the absorbent core 28 and the top sheet 22. The topsheet 22 can preferably be attached thereto and the backsheet 24 by attachment (not shown) such as those well known in the art. The suitable joining means is described below with respect to the attachment of the backsheet 24 to the absorbent core 28. As used herein, the term "attached" encompasses the configurations by which one element is directly secured to the other element by fixing the element directly to the other element, and the configurations by means of which the element indirectly assures the other element by fixing the element to a member or intermediate members which in turn are fixed to the other element. In a preferred embodiment of the present invention, the topsheet and backsheet are directly bonded together at the periphery of the diaper and can be indirectly joined together by attaching them directly to the absorbent core by means of the attachment means (not shown). In an alternate embodiment, the absorbent core (or the preferred acquisition material) need not be attached to either the top sheet or the back sheet so that the absorbent core is allowed to "float" between them. The backsheet 24 is impermeable to liquids (eg, urine) and is preferably manufactured from a thin plastic film, although other flexible materials impervious to liquid can also be used. As used herein, the term "flexible" refers to materials that are docile and will readily conform to the contour and general shape of the human body. The backsheet prevents the exudates absorbed and contained in the absorbent core from wetting the articles that are in contact with the diaper as sheets and undergarments. The backsheet may thus comprise a woven or non-woven material, polymeric films such as polyethylene or polypropylene thermoplastic films, a composite material such as a film-coated nonwoven material. Preferably, the backsheet is a thermoplastic film having a thickness of about 0.012 millimeters to about 0.051 millimeters. In a preferred embodiment of the present invention, at least a portion of the backsheet is subjected to mechanical stretching for the purpose of providing both a stretch laminate with "null deformation" which forms the elastic side panels and, if desired , preforming the part of the back sheet that matches the elastic waist feature or any other elastic feature. In this way, the backsheet is preferably stretchable, very preferably stretchable, but not necessarily elastomeric, such that the backsheet will be, at the time of mechanical stretching, at least permanently elongated to a degree such that it will not return completely to its original, undistorted configuration. In preferred embodiments, the backsheet can be subjected to mechanical stretching without undue rupture or tearing. In this way, it is preferred that the backsheet has an elongation before final breaking of at least about 400% to about 700% in the transverse direction of the machine as measured using the method consisting of ASTM D-638. Therefore, preferred polymeric films for use as the backsheet have a high content of linear low density polyethylene. Particularly preferred materials for the backsheet include blends composed of about 45 to 90% linear low density polyethylene and about 10 to 55% polypropylene. Exemplary films to be used as the backsheet of the present invention are manufactured by Tredegar Industries, Inc. of Terre Haute, Indiana, under the designations X-8323, RR8220 mixture of certain blown films, and RR5475 mixture for certain voided films.

The backsheet 24 is typically embossed which (typically, to a caliper of approximately 0.127 mm) and / or finished dull to provide a more fabric-like appearance. In addition, the backsheet can allow vapors to escape from the absorbent core (ie, breathable) while still preventing the passage of exudates through the backsheet. The backsheet 24 is positioned adjacent the bottom surface of the absorbent core 28 and may be attached thereto by attachment means (not shown) such as those well known in the art. Alternatively, an additional material (eg, acquisition material) can be placed between the backsheet 24 and the absorbent core 28. for example, the backsheet 24 can be secured to the absorbent core 28 or any intermediate material by a layer uniform, continuous adhesive, a patterned adhesive layer, or an array of separate lines, spirals, or spots of adhesive. The adhesives that have been found to be satisfactory are manufactured by Century Adhesives, Inc. of Columbus, Ohio, and are marketed as Century 5227; and by H. B. Fuller Company of St. Paul, Minnesota, and are marketed as HL-1258. The attachment means preferably comprises an open pattern web of adhesive filaments as disclosed in United States Patent No. 4,573,986 entitled "Disposable Garbage Containment Garment" which was issued to Minetola and Tucker on March 4, 1986. An exemplary joining means of an open filament pattern network comprising several lines of adhesive filaments twisted in a spiral pattern as illustrated by the apparatus and methods shown in U.S. Patent No. 3,911,173 issued to Sprague, Jr. on October 7, 1975; U.S. Patent No. 4,785,996 issued to Ziecker et al. on November 22, 1978; and in U.S. Patent No. 4,842,666 issued to Werenicz on June 27, 1989. Alternatively, the joining means may comprise heat joints, pressure joints, ultrasonic joints, mechanical dynamic joints, or any other means of bonding. suitable binding or combinations of these joining means as are known in the art. The absorbent core 28 will comprise any absorbent material which is capable of absorbing and retaining liquids such as urine or other certain exudates from the body, and which is capable of providing the distribution / storage properties of the fluid that is defined in the present invention. Although the absorbent core 28 is shown in Figure 1 in an "I" configuration, any shape can be used. For example, an absorbent core 128 in an "hourglass" configuration is shown in FIG. 12, wherein the core has arcuate cutouts at its longitudinal edges, indicated generally as 142. For purposes of illustration, the point between legs is identified by detail 127. (As discussed above, the crotch point of the absorbent core is extrapolated from the user.) As shown, the crotch point 127 is generally located on the longitudinal center line 127 and on the line transversal 168 (although not the transversal center line in this modality). The inter-leg region is determined by the forward measurement of the crotch point at a distance of 25% of the total length of the core (represented as the transverse line 161) and back from the inter-leg point at a distance of 25% of the total length of the core (represented as the transverse line 163). The crotch region 156, is the region of the core between the transverse lines 161 and 163. In addition to the crotch region 156, the core 128 has a front region 152 and a back region 154. Figure 3 illustrating another diaper and the corresponding core configuration. In particular, diaper 220 is configured to fit within the user's low movement zone. (A disclosure of the articles under movement and the corresponding cores is described in detail in U.S. Pat. No. 5, LaVon 358,500 and others, the disclosure of which is incorporated herein by reference.) The absorbent core, generally represented as 228, is also configured to fit within the user's low movement zone. Figure 4 illustrates the means for determining the crotch point of an article and its absorbent core. Referring to Figure 4, the legs of a standing user are depicted in cross-sectional manner as 301 and 302. A continuous material 303 (eg, a cord or rubber band) is twisted once and is placed or around of the legs of the wearer at a point sufficiently close to the torso of the wearer so that the intersection 304 of the material 303 can be extrapolated onto the article being worn. The crotch point of the core of the article is determined thus, and the crotch region of the core is determined by the above description. The width of the crotch of the absorbent core, when dry and when wet, is also important in providing the improved fit to the wearer. It is preferred that the width of the crotch be small, even when sheeting with the fluid, such that the absorbent core suffers minimal bulge when the user's legs. In this regard, the absorbent cores useful in the present invention will have a crotch width when they are dry and when they are wet no greater than about seven centimeters. In such low volume configurations, the width of the crotch when it is dry and when wet is preferably not more than about six centimeters, even more preferably not more than about five centimeters. The means to measure the width of the crotch is described in the section on Test Methods, infra. It is preferred that at the crotch point of the absorbent core, the core has a relatively small cross-sectional area (dimension X per dimension Z). In this regard, absorbent cores useful in the present invention will preferably have a cross-sectional area, when dry, no greater than about 2.6 cm 2. Preferably, the cross-sectional area of the crotch, when dry, will not be greater than about 1.8 cm2, more preferably not greater than about 1 cm2, even more preferably not greater than about 0.6 cm2, most preferably not greater than about 0.4 cm2 . The means for measuring the cross-sectional area are described in the Test Methods section, infra. It turns out that a reduction in the cross-sectional area and / or crotch width of an absorbent core with a uniform capacity per unit area surface necessarily reduces the amount of material and the capacity in the liquid deposition zone. Previous attempts to improve the fit by reducing the width in the crotch region were made in such a way by increasing the capacity per unit surface area to maintain the necessary capacity in the crotch region. These previous attempts used additional fiber in the leg region for liquid absorption and in some examples additional hydrogel-forming polymers for liquid storage. These approaches therefore result in a negative impact on both dry and wet volume. The direct contrast, the present invention is intended to move fluid deposited 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, in the crotch region of the absorbent core will comprise a material or materials that function to distribute the fluids away from the crotch region. (Although the distribution of the fluid is an important function of the core crotch region material, it is within the scope of the invention to include materials in the leg region whose primary function is the storage of fluids, as long as the required properties of the present invention are achieved.) In particular, the absorbent core of the articles of present will comprise a material exhibiting an ability to move significant amounts of fluid out of the crotch region of the article, even after relatively long periods of time. This ability for capillary absorption or vertical wicking effect, ie the capillary absorption of fluid in an opposite direction of gravity, is an important performance attribute since the absorbent cores are used in absorbent articles in such a way that the fluid that is absorbed must be translated into the article from a relatively lower position to a relatively higher position within the core of the article. This ability to move the fluid against the force of gravity is of particular importance to the present invention, giving these relatively small levels of fluid to be stored in the crotch region of the core. In this regard, the absorbent cores will comprise a material having a F10 value of at least about 0.5 g / cm2 / minute. The material will preferably have a value of F10 of at least about 0.6 g / cm2 / minute, more preferably at least about 0.8 g / cm2 / minute, more preferably at least 1 g / cm2 / minute, more preferably at least about 2 g / cm2 / minute, more preferably at least about 3 g / cm2 / minute and most preferably at least about 5 g / cm2 / minute. Alternatively or in addition, the absorbent cores of the present invention will comprise a material having a F30 value of at least about 0.3 g / cm2 / minute. In this regard, the material will preferably have a value of F30 of at least about 0.4 g / cm2 / minute, more preferably at least about 0.5 g / cm2 / minute, more preferably at least about 1 g / cm2 / minute, yet more preferably at least about 1.5 g / cm2 / minute, and most preferably at least about 3 g / cm2 / minute. In a particularly preferred embodiment, the absorbent core will comprise a material having an IF10 value of at least about 0.5 g / cm2 / minute and a F30 value of at least about 0.3 g / cm2 / minute. The absorbent articles of the present invention will also comprise an absorbent core which in equilibrium retains less than about 40% of the total absorbent capacity of the core in the crotch region of the core. Of course, the storage of smaller amounts of fluid within the crotch region of the core, relative to the front / back regions of the core, is a reflection of the ability of the core materials to move fluid out of the region of the core. crotch during use, and in this way improve the fit and comfort to the user. In this regard, the absorbent cores useful in the present invention will preferably retain less than about 25%, more preferably less than about 15%, even more preferably from 0% to about 10%, of the total core capacity in equilibrium in the region crotch of the nucleus. As discussed above, the absorbent core will comprise a material that functions to distribute the fluid outside the region of between the core leg. In one embodiment, the absorbent core will comprise the same material in the front and back of the core as it is contained in its crotch region. That is to say. The distribution material will also be suitable for fluid storage. Alternatively, the core may contain a storage material other than capillary suction superior in the frontal and posterior regions of the nucleus. This storage material will then desorb the relatively lower capillary suction distribution materials. A preferred absorbent material for providing the required distribution properties is an open cell absorbent polymeric foam material which is derived by the polymerization of a high internal phase water-in-oil emulsion (hereinafter referred to as an EAFI). These polymeric foams can be formed to provide the required storage properties, as well as the distribution properties required. Where different storage materials are included in the front and back sections of the core, the polymeric distribution foams will preferably exhibit desorption properties that allow them to other core components (which have absorption pressures greater than the desorption pressure of the core). distribution foam) to move the fluid away. It is desirable that this component keeps the user's skin dry, even in situations of. "jet" and even when subjected to a compression load; it is soft, flexible and comfortable for the user of the absorbent article; and has a relatively high capacity for the fluid to provide diapers and other absorbent articles that efficiently utilize the core components. Foams derived from the EAFI that provide both required distribution and storage properties for use herein are disclosed in copending US patent application Serial No. 08 / 563,866 (DesMarais et al.), Filed November 25, 1995 (hereinafter referred to as the 866 application); U.S. Patent No. 5,387,207 (Dyer et al.), issued February 7, 1995; and U.S. Patent No. 5, 260,345 (DesMarais et al.), issued November 9, 1993; the disclosure of each of which is hereby incorporated by reference. The polymeric foams useful in the present invention are those that are relatively open cell. This means that a significant proportion of the individual cells of the foam is in communication with adjacent cells. The cells in these substantially open cell foam structures have intercellular openings or "windows" that are large enough to allow easy transfer of fluid from one cell into the other within the foam structure. These substantially open-cell foam structures will generally have a cross-linked character with the individual cells that are defined by a plurality of three-dimensionally branched, mutually connected frames. The branches of the polymer material forming these branched webs can be referred to as "struts". Open cell foams having a typical strut type structure are shown by way of example in the micro photographs of Figures 1 and 2 in application 866. As used herein, a foam material is "open cell" "if at least 80% of the cells in foam structure that are at least 1 μm in size are in fluid communication with at least one adjacent cell. In addition to being open cell, these polymeric foams are sufficiently hydrophilic to allow the foam to absorb aqueous fluids in the amounts specified below. The internal surfaces of the foam structures are made hydrophilic by residual hydrophilizing surfactants left inside the foam structure after the polymerization, or by selected foam treatment processes after polymerization. Polymeric foams can be prepared in the form of collapsed polymer foams (ie, without expander) which, upon contact with aqueous fluids, expands and absorbs these fluids. See, for example, the co-pending patent application United States No. 08 / 563,866 and United States patent No. 5,387,207. These collapsed polymeric foams are normally obtained by squeezing the water phase of the polymerized EAFI foam through compression forces, and / or by thermal drying and / or vacuum drying. After compression, and / or thermal drying / vacuum drying, the polymeric foam is in a collapsed or unexpanded state. Non-collapsible foams, such as those described in the copending patent application Serial No. 08 / 542,497 and U.S. Pat. No. 5,260,345 are also useful as in distribution material. An important parameter of these foams is their glass transition temperature. A Tg represents the midpoint of the transition between the vitreous and rubber consistency states of the polymer. Foams that have a Tg higher than the temperature of use can be very resistant but will also be very rigid and potentially prone to fracture. When these foams are collapsible, they typically also take a long time to recover to the expanded state when they are wetted with colder aqueous fluids than the Tg of the polymer after being stored in the collapsed state for prolonged periods. The desired combination of mechanical properties, specifically resistance and resilience, typically need a range of monomer types and fairly selective levels to achieve these desired properties. It has been found that the specific surface area per volume of foam of the polymeric foam is particularly useful for empirically defining the foam structures that will remain in a collapsed state. Furthermore, this property is important for the ability of the foam to provide the capillary absorption or wicking flow values discussed herein. See United States Patent No. 5,387,207, where it was discussed in detail in the specific surface area by volume of foam. "Specific surface area by foam volume" refers to the specific surface area of capillary suction of the foam structure by its foam density in the expanded state. Polymeric foams having specific surface area values per foam volume of at least about 0.025 m2 / cm3, more preferably at least about 0.05 m2 / cm3, most preferably at least about 0.07 m2 / cm3, were found to be empirically they remain in a collapsed state, and are therefore preferred here. Another important property of absorbent polymer foams useful herein is their free absorbent capacity. The "absorbent free capacity" is the total amount of test fluid (synthetic urine) that a given sample of foam will absorb into its cellular structure per unit mass of the solid material in the sample. To be especially useful in the absorbent articles of the present invention, the absorbent foams should have a free absorbent capacity of about 100 ml, preferably about 55 to about 75 ml of synthetic urine, per gram of the dry foam material. The process for terminating the free absorbent capacity of the foam is described in the TEST METHODS section of the application 866. Upon exposure to aqueous fluids, the collapsible foams useful herein expand and absorb fluids. When these foams are dewatered by compression to a thickness of approximately 1/6 (17%) or less of their fully expanded thickness, they remain in a very thin state, with a concomitant increase in storage efficiency and flexibility. This is attributable to the low density of expanded foams. The "expansion factor" for these foams is at least 4X, that is, the thickness of the foam in its expanded state is at least four times the thickness of the foam in its collapsed state. The collapsed foams preferably have an expansion factor on the scale of about 4X to about 10X. By comparison, the above higher density foams typically have an expansion factor of only 4X to 5X. For the purposes of the present invention, the relationship between expanded and collapsed thickness for collapsible foams dewatered by compression can be empirically approximated from the following equation: Thickness (expanded) = thickness (collapsed) x 0.133 x W: O ratio where the "thickness (expanded)" is the foam thickness in its expanded state; "thickness (collapsed)" is the thickness of foam in its collapsed state; and the "W: O ratio" is the water to oil ratio of the high internal phase emulsion from which the foam is made. In this manner, a typical foam made from an emulsion having a water to oil ratio of 60: 1 would have a predicted expansion factor of 8.0, that is, eight times the expanded thickness of the collapsed thickness of the foam. The method for measuring the expansion factor is described in the Test Methods section of the application 866. An important mechanical feature of the absorbent polymeric foams useful in the present invention is its strength in its expanded state, as determined by its strength to compression deflection (RTCD). The RTCD exhibited by the foams is a function of the polymer module, as well as the density and structure of the foam network. The polymer module is, in turn, determined by: a) the composition of the polymer; b) the conditions under which the foam is polymerized will be identical to, for example, the integrity of the obtained polymerization, specifically with respect to crosslinking); and c) the limit at which the polymer is plasticized by the waste material, for example, emulsifiers, left in the foam structure after processing. To be useful as absorbers in absorbent articles such as diapers, the foams of the present invention must be adequately resistant to deformation or compression by the forces encountered during use when these absorbent materials are responsible for absorption and retention of the fluid. Foams that do not possess sufficient foam resistance in terms of RTCD may be able to acquire and store acceptable amounts of body fluid under conditions of no charge but will very easily lose their fluid under the compression forces caused by movement and activity of the user. of the absorbent articles that contain the foam. The RTCD exhibited by the polymeric foams useful in the present invention can be quantified by determining the amount of stress produced in the saturated foam sample held under a certain confining pressure for a specific temperature and period of time. The method for performing this type of particular test is described in the TEST METHODS section of the application 866. The foams useful as absorbers are those that exhibit an RTCD such that a confining pressure of 5.1 kPa produces a stress or strain of typically about 40% or less of compression of the foam structure when it has been saturated to its free absorbent capacity with synthetic urine, which has a surface tension of 65 + -5 dynes / cm. Preferably, the stress produced under conditions will be in the range of about 2 to about 25%, more preferably about 2 about 15%, most preferably about two about 10%. Foam cells, and especially cells which are formed by polymerizing an oil phase containing monomer surrounding drops of the relatively monomer-free water phase, will often be substantially spherical in shape. The size or "diameter" of these spherical cells is a parameter commonly used to characterize foams in general. Since the cells in a given sample of polymeric foam will not necessarily be of approximately the same size, an average cell size, for example, diameter is average cell, will often be specified. A number of techniques are available to determine the average cell size of the foams. The most useful technique, however, for determining cell size and foams involves a simple measurement based on the electronic scanning micro-photography of a foam sample. The cell size measurements given herein that are based on the average cell size in number of the foam in its expanded state. The foams useful as absorbers for the aqueous fluids according to the present invention will preferably have a number average cell size of about 50 μm or less, and typically from about five about 35 μm. The "foam density" (ie, in grams of foam per cubic centimeter of the volume of foam in air) is specified here on a dry basis. The amount of the water-soluble waste materials absorbed, for example, the residual salts and liquid left in the foam, for example, after the polymerization of the EAFI, washing and / or hydrophilization, is discarded when calculating and expressing the density of the waste. foam. However, the foam density includes other water insoluble waste materials such as the emulsifiers present in the polymerized foam. These residual materials can, in fact, contribute significant mass to the material (foam.) Any suitable gravimetric procedure that will provide a mass determination of the solid foam material per unit volume of foam structure can be used to measure the density of the foam. For example, an ASTM gravimetric process described more fully in the Test Methods section of U.S. Patent No. 5,387,207 is a method that can be employed for density determination.In its crushed state, foams Polymers of the present invention useful as absorbers have dry basis density values in the range from about 0.1 to about 0.2 g / cm3, preferably from about 0.11 to about 0.15 g / cm3, and most preferably from 0.12 to 0.14 g / cm3 In its expanded state, the polymeric foams of the present invention useful as Absorbents have density values on a dry basis in the range from about 0.010 to about 0.018 g / cm3, preferably from about 0.013 to about 0.018 g / cm3. Suitable absorbent foams in general will exhibit especially desirable and useful aqueous fluid handling and absorbency characteristics. In particular, when the foam is used as a main distribution material in an absorbent core of the present invention, the ability to move the fluid from the crotch region of the core to the front and / or back regions of the core is important. core. The characteristics of fluid handling and absorbency that are very relevant for the fluid distribution foams are: A) the coefficient of capillary absorption or vertical wicking effect of the fluid through the structure of the foam; and B) the amount of fluid, per dry cross-sectional area of the material, which is removed from the core crotch region over relatively long periods of time (eg, 10 and 30 minutes). Another important property of the foams is the ability to drain (distribute) the fluid from the concurrent absorbent structures with which the foam may be in contact. The vertical capillary absorption or vertical wicking effect, ie the capillary absorption of the fluid in an opposite direction of gravity, is an especially desirable performance attribute for the absorbent foams herein. These foams will often be used in absorbent articles in a manner such that the fluid that is absorbed must be translated into the article from a relatively lower position to a relatively higher position within the core of the article. Accordingly, the ability of these foams to move the fluid against the force of gravity is of particular importance for their operation as the absorbent materials in the absorbent articles present. The vertical capillary absorption flow test measures the amount of test fluid per dry cross-sectional area of the absorbent foam that is removed from a fluid reservoir per minute, evaluated at 10 and 30 minute times. This determination is made after the sample has been allowed to vertically absorb the test fluid for the desired period of time. The vertical capillary absorption flow test is described in more detail in the TEST METHODS section below. Another important property of the absorbent foams useful in accordance with the present invention is its capillary absorption pressure. The capillary absorption pressure refers to the ability of the foam to wick the fluid vertically. [See, P. K. Chatterjee and H. V. Nguyen in "Absorbency," Textile Science and Technology Vol. 7; P. K. Chatterjee, Ed .; Elsevier: Amsterdam, 1985; Episode 2]. For the purposes of the present invention, the capillary absorption pressure of interest is the hydrostatic head, at which the vertically driven fluid load by wicking effect is 50% of the absorbent capacity under equilibrium conditions at 31 ° C. The hydrostatic head is represented by a column of fluid (eg, synthetic urine) of height h. To be especially useful in absorbent articles for absorbing aqueous fluids, the absorbent foams useful herein will generally have capillary absorption pressures of at least about 24 cm. (The foams of the present invention typically have absorption pressures of about 30 to about 40 cm). In those embodiments where the distribution material is not particularly suitable for storing the absorbed fluids, the absorbent core will also comprise a material, or combinations of materials, whose main function is the storage of one of the absorbed fluids. The material a material is fluid storage act to store the body exudates away from the user's body to leave the user with a feeling of dryness. The storage materials are maintained in fluid contact with the distribution material or materials in such a manner that the urine or other aqueous body fluids absorbed by the distribution material can be desorbed by the fluid storage material. When placing the storage materials in the front and / or back regions of the absorbent core, the core provides adjustment benefits by storing a majority of the absorbed fluids away from the crotch region of the article. Any material capable of desorbing the distribution material can be used as the storage material. For example, the storage material may comprise hydrogel-forming polymers that are insoluble in water, but capable of swelling in water and are capable of absorbing large quantities of fluids. These polymers are commonly referred to as "hydrocolloids" or "superabsorbent" materials, and may include polysaccharides such as carboxymethyl starch, carboxymethyl cellulose, and hydroxypropyl cellulose; nonionic types such as polyvinyl alcohol, and polyvinyl ethers; cationic types tai such as polyvinyl pyridine, polyvinyl morpholinone, and N, N-dimethylaminoethyl or N, N-diethylaminopropy acrylates and methacrylates, and the respective quaternary salts thereof. Typically, hydrogel-forming absorbent polymers, useful herein have a multitude of functional anionic groups, such as sulfonic acid, and more typically carboxy groups. Examples of polymers suitable for use herein include those which are prepared from acid-containing, polymerizable, unsaturated monomers. In this way, said monomers include the olefinically unsaturated acids and anhydrides, which contain at least one olefinic carbon-to-carbon double bond. More specifically, these monomers can be selected from carboxylic acids and olefinically unsaturated acid anhydrides, olefinically unsaturated sulfonic acids, and mixtures thereof. Some monomers without acid, usually in minor amounts, may also be included to prepare the hydrogel-forming absorbent polymers. Such monomers without acid may include, for example, water-soluble or water-dispersible esters of the acid-containing monomers, as well as monomers that do not contain any carboxylic acid or sulfonic acid group. Thus, optional acid-free monomers containing the following types of functional groups may be included: carboxylic acid or sulfonic acid esters, hydroxyl groups, amide groups, amino groups, nitrile groups and quaternary ammonium salt groups, aryl groups (for example, phenyl groups, such as those derived from the styrene monomer). These acid-free monomers are well known materials and are described in greater detail, for example, in U.S. Patent No. 4,076,663 (Masuda et al.), Issued February 28, 1978, and the United States patent of America No. 4,062,817 (Westerman), issued December 13, 1977, both incorporated herein by reference. The carboxylic acid and olefinically unsaturated carboxylic acid anhydride monomers include the acrylic acids illustrated by the same acrylic acid, methacrylic acid, ethacrylic acid, α-chloroacrylic acid, α-cyanoacrylic acid, β-methacrylic acid (crotonic acid), a-phenylacrylic acid, β-acryloxypropionic acid, sorbic acid, a-chlorosorbic acid, angelic acid, cinnamic acid, p-chloro cinnamic acid, β-sterilacrylic acid, itaconic acid, citroconic acid, mesaconic acid, glutaconic acid, aconitic acid, maleic acid, fumaric acid, tricarboxyethylene and maleic acid anhydride. Olefinically unsaturated sulfonic acid monomers include aliphatic or aromatic vinylsulfonic acids such as vinylsulfonic acid, allylsulfonic acid, vinyltoluenesulfonic acid and styrenic acid; acrylic and methacrylic acid, such as sulfoethyl acrylate, sulphoethyl methacrylate, sulfopropyl acrylate, sulfopropyl methacrylate, 2-hydroxy-3-methacryloxypropylsulfonic acid and 2-acrylamide-2-methylpropanesulfonic acid. Preferred hydrogel-forming absorbent polymers for use in the present invention contain carboxy groups. These polymers include starch-acrylonitrile hydrolyzed graft copolymers, partially neutralized starch-acrylonitrile graft copolymers, starch-acrylic acid graft copolymers, partially neutralized graft copolymers of starch-acrylic acid, saponified copolymers of vinyl acetate-ester acrylic, hydrolyzed acrylonitrile or acrylamide copolymers, polymers slightly entangled in the network structure of any of the above copolymers, partially neutralized polyacrylic acid, and polymers slightly entangled in the network structure of partially neutralized polyacrylic acid. These polymers can be used either alone or in the form of a mixture of two or more different polymers. Examples of these polymer materials are described in U.S. Pat. No. 3, 661,875, U.S. Patent No. 4,076,663, U.S. Patent No. 4,093,776, U.S. Patent No. 4,666,983 and U.S. Patent No. 4,734,478. The most preferred polymer materials for use herein are polymers slightly entangled in the network structure of partially neutralized polyacrylic acids and their starch derivatives. Most preferably, the precursor particles comprise from about 50 to about 95%, preferably about 75% neutralized, polyacrylic acid, lightly entangled in the network structure, (ie, poly (sodium acrylate / acrylic acid)). The interlacing of the network structure makes the polymer substantially insoluble in water and, in part, determines the absorptive capacity and the extractable polymer content characteristics of the hydrogel-forming absorbent polymers. The procedures for network structure interleaving of polymers, and typical network structure entanglement agents, are described in more detail in the aforementioned US Pat. No. 4,076,663. The hydrogel-forming polymers may optionally be combined with fibrous materials to form the storage material. The fibrous materials facilitate, inter alia, the uptake of the fluid by the hydrogel-forming polymer. However, it may be preferred to use relatively high concentrations of hydrogel-forming polymer, while at the same time avoiding the phenomenon of the gel block exhibited by many of the hydrogel-forming polymers. The use of high concentrations of hydrogel-forming polymers is described in detail in U.S. Patent No. 5,599,335 (Goldman et al.) And U.S. Patent No. 5,562,646 (Goldman et al.), Both of which are incorporated herein by reference. by reference here. The storage materials comprising hydrogei-forming polymers can also comprise fibrous materials to form the fibrous web or fibrous matrices. The fibers useful in the present invention include those which are naturally occurring fibers (modified or unmodified), as well as synthetically produced fibers. Examples of naturally occurring unmodified or modified, suitable fibers include cotton, esparto grass, bagasse, kemp, flax, silk, wool, wood pulp, chemically modified wood pulp, jute, rayon, ethyl cellulose and cellulose acetate. Suitable synthetic fibers can be made of polyvinyl chloride, polyvinyl fluoride, polytetrafluoroethylene, polyvididene chloride, polyacrylics, such as orlon, polyvinyl acetate, polyethyl vinyl acetate, soluble or insoluble polyvinyl alcohol, polyolefins such as polyethylene (e.g. PULPEX®) and polypropylene, polyamides such as nylon, polyesters such as DACRON® or DOLE®, polyurethanes, polystyrenes and the like. The fibers used may comprise only naturally occurring fibers, synthetic fibers only or any compatible combination of naturally occurring and synthetic fibers. The fibers used can be hydrophilic, hydrophilized, or can be a combination of both hydrophilic and hydrophobic fibers. As used herein, the term "hydrophilic" describes fibers, or surfaces of fibers that are wettable by aqueous fluids, (eg, aqueous body fluids), deposited on these fibers. The hydrophilic capacity and wettability of individual fibers is typically defined in terms of the contact angle and surface tension of the fluids and solids involved. This is discussed in detail in the American Chemical Society's publication Angle of Contact, Moisture and Adhesion, edited by Robert F. Gould (Copyright 1964). A fiber, or the surface of a fiber, is said to be moistened by a fluid (ie, hydrophilic), when either the contact angle between the fluid and the fiber, or its surface is less than 90 °, or when the fluid tends to spontaneously disperse through of the surface of the fiber, both conditions coexisting normally. Conversely, a fiber or surface that is hydrophobic is considered if the contact angle is greater than 90 ° and the fluid is not spontaneously spreading through the surface of the fiber. For the storage materials useful herein, the use of hydrophilic fibers is preferred. Hydrophilic fibers for use in the present invention include cellulosic fibers, modified cellulosic fibers, rayon, polyester fibers such as polyethylene terephthalate (for example DACRON®), hydrophilic nylon (HYDROFIL®), and the like. Suitable hydrophilic fibers can also be obtained by hydrophilizing the hydrophobic fibers, such as the thermoplastic fibers treated with surfactant or treated with silica, derived from, for example, polyolefin such as polyethylene or polypropylene, polyacrylics, polyamides, polystyrenes, polyurethanes and the like. For reasons of availability and cost, cellulosic fibers, in particular wood pulp fibers, are preferred for use in the present invention. Suitable wood pulp fibers can be obtained from well-known chemical processes such as Kraft and sulfite processes. It is especially preferred that these derive from softwood pulp fibers from the south, due to their excellent absorbency characteristics. These wood pulp fibers can also be obtained from mechanical processes such as wood processes at ground level, processes of refined mechanical pulp, thermomechanical-chemical mechanical and chemical-thermomechanical. Recycled or secondary wood pulp fibers as well as bleached and unbleached wood pulp fibers can be used. A desirable source of hydrophilic fibers for use in the present invention is the chemically hardened cellulosic fibers. As used herein the term "chemically hardened cellulosic fibers" means the cellulosic fibers that have been hardened by chemical means to increase inflexibility under both dry and aqueous conditions. This medium can include the addition of a chemical curing agent, for example, coated and / or impregnated in the fibers. These means may also include hardening the fibers by altering the chemical structure, for example, by crosslinking the polymer chains. Polymeric curing agents that can coat or impregnate cellulosic fibers include: modified cationic starches having nitrogen-containing groups (e.g., amino groups) such as those available from National Starch and Chemical Corp., Bridewater, NJ. USA; latex; wet strength resins such as polyamide-epichlorohydrin resin (eg, Kymene 557H, Hercules, Inc., Wilmington, Delaware, USA), polyacrylamide resins described, for example, in U.S. Patent No. 3,556,932 ( Coscia et al.), Issued on January 19, 1971; commercially available polyacrylamides sold by American Cyanamid Co., Stamford, CT, USA, under the trade name Parez 631 NC; urea formaldehyde and melamine formaldehyde resins, and polyethylene imine resins. A general dissertation on wet strength resins used in the paper technique, and the application generally here, can be found in the TAPPI monograph series No. 29. "Wet Streng in Paper and Paperboard", technical association of the industry of pulp and paper (New York, 1965). These fibers can also be hardened by chemical reaction. For example, the crosslinking agents can be applied to the fibers which, after application, are chemically formed to form intrafiber lattice bonds. These lattice bonds can increase the inflexibility of the fibers. Although the use of intrafiber lattice bonds to chemically harden fiber is preferred, it is not meant to exclude other types of reactions for chemical hardening of fibers. The fibers hardened by the lattice bonds in an individualized manner (i.e., individualized hardened fibers take that as well as the processes for their preparation) are disclosed, for example, in U.S. Patent No. 3,224,926 (Bernardin) issued on December 21, 1965, U.S. Patent No. 3,440,135 (Chung), issued April 22, 1969; U.S. Patent No. 3,932,209 (Chatterjee), issued January 13, 1976; and U.S. Patent No. 4,035,147 (Sangenis et al.), issued December 19, 1989; U.S. Patent No. 4,898, 642d (Moore et al.) issued February 6, 1990; and U.S. Patent No. 5,137,537 (Herron et al.), issued August 11, 1992.

In presently preferred hardened fibers, the chemical process includes crosslinking between the fibers with crosslinking agents while such fibers are in a relatively dehydrated, defibrated (eg, individualized), twisted, crimped condition. Chemical hardening agents are typically monomeric crosslinking agents including, but not limited to, C2-C8 dialdehyde, C2-C8 monoaldehydes having an acidic functionality, and especially C2-C9 polycarboxylic acids. These compounds are capable of reacting with at least two hydroxyl groups in an individual cellulose chain or close to the cellulose chains located in a single fiber. The specific examples of these agents of -IX) crosslinking include, but are not limited to, glutaraldehyde, glyoxal, formaldehyde, glyoxylic acid, oxydisuccinic acid, and citric acid. The effect of crosslinking under these conditions is to form fibers that are hardened and tend to retract their twisted, crimped configuration, during use in thermally bonded absorbent structures herein. These fibers, and the processes for making them, are described in the patents before incorporated. Such hardened fibers that are twisted and crimped can be quantified by referencing both a "twist count" of fiber and a "curl factor" of the fiber. As used herein, the term "twist count" refers to the number of torsion nodes present in a certain length of fiber. The torsion count is used as a means to measure the degree to which the fiber is rotated around its longitudinal axis. The term "twist knot" refers substantially to an axial rotation of 180 ° around the longitudinal axis of the fiber, wherein a portion of the fiber (eg, the "knot") appears relatively dark to the rest of the fiber when It is observed under the microscope with transmitted light. The twist knot appears dark in locations in which the The transmitted light passes through an additional fiber wall due to the aforementioned rotation. The distance between the knots corresponds to an axial rotation of 180 °. The number of torsion nodes in a certain length of fiber (for example the torsion count) is directly indicative of the degree of torsion of the fiber, which is a physical parameter of the fiber. The procedures for determining the torsional knots and the total torque count are described in U.S. Patent No. 4,898,642. The preferred hardened fibers will have an average dry fiber twist count of at least about 2.7, preferably about 4.5 twists, knots per millimeter. In addition, the average wet fiber twist count of these fibers is preferably at least about 1.8, preferably at least about 3.0, and preferably should also be at least about 0.5 knots per millimeter less than the bill. of average dry fiber twist. Even more preferably, the average dry fiber twist count should be at least about 5.5 knots per millimeter, and the average wet fiber torsion count should be at least 4.0 knots per millimeter and it must also be at least 1.0 knots of torque per millimeter less than your average dry fiber twist count. More preferably, the average dry fiber twist count should be at least about 6.5 knots per millimeter, and the average wet fiber torsion count should be at least about 5.0 knots per millimeter and it must also be at least 1.0 knots of torque per millimeter less than the average dry fiber twist count. In addition to being twisted, these preferred hardened fibers are also crimped. The curl of the fiber can be described as the fractional shortening of the fiber due to the curls, twists and / or curvature in the fiber. For the purposes of the present invention, the fiber curl is measured in terms of a two-dimensional plane. The extent of the curling fiber can be quantified by reference to a fiber curl factor. The fiber curl factor, a measure of two dimensions of the curl, is determined by observing the fiber in a two-dimensional plane. To determine the curl factor, both of the projected length of the fiber are measured as the longest dimension of a two-dimensional rectangle surrounding the fiber, LR, and the current length of the fiber, LA. Then, the fiber curl factor can be calculated by the following equation: Curl factor = (LA / LR) - 1.

An image analysis method that can be used to measure LR and LA is described in U.S. Patent No. 4,898,642. Preferably, the hardened fibers will have a curl factor of a! less around 0.30 and more preferably will have a curl factor of at least about 0.50. These chemically hardened cellulosic fibers have certain properties that make them particularly useful in certain absorbent members according to the present invention, relative to uncured cellulosic fibers. In addition to being hydrophilic, these hardened fibers have unique combinations of hardness and resilience. This allows the thermally bonded absorbent structures made with these fibers to maintain high levels of absorbency, and exhibit high levels of resilience and a response to expansion upon wetting. In particular, the resilience of these hardened fibers allows the absorbent member to better maintain its capillary structure in the presence of both fluid and compression forces normally encountered during use and is thus more resistant to collapse. A preferred storage material for practicing the present invention comprises a polyurethane foam material derived from the EAFIs. These materials will preferably have sufficient absorption pressures to desorb the distribution material, thus providing reduced fluid storage in the crotch region of the article. However, as indicated, a simple material can function as both the distribution material and the storage material in the present articles. The foams described above with reference to the distribution component of the absorbent articles present are also useful as the storage component of the articles. Particularly preferred are collapsible polymeric foam materials which, upon contact with aqueous fluids (in particular aqueous body fluids such as urine), can expand and absorb these fluids. These absorbent polymeric foam storage materials comprise a non-ionic, flexible, hydrophilic polymeric foam structure of interconnected open cells as described in, for example, U.S. Patent No. 5,387,207 (Dyer et al.) Issued on 7 February 1995, and the co-pending United States patent application Serial No. 08 / 563,866 (DesMarais et al.) filed on November 25, 1995, the disclosure of each of which is hereby incorporated by reference . The foam storage material useful in the present invention provides very low density absorbent foams. For a given expanded thickness, these lower density foams more efficiently utilize the capacity of the polymeric material. As a result, low density absorbent foams provide an economically attractive means to achieve thinner absorbent cores for absorbent articles such as diapers, pads or adult incontinence pads, sanitary napkins, and the like. This is achieved while the absorbency and desired mechanical properties are provided. The materials used in the absorbent core of the present articles may be arranged in a variety of ways, while the required distribution material is included in the crotch region. As discussed above, it is preferred to have relatively little fluid storage in the crotch region. In this way, while storage materials that do not function to distribute the fluid may be present in the crotch region of the absorbent core, the main material of the crotch region will be the distribution or redistribution / storage material. The absorbent cores useful herein may comprise separate components for use in the crotch portions, front and back, of the absorbent core. Figure 5 shows an exploded perspective view showing the elements of an absorbent core 428. As shown in Figure 5, the absorbent core 428 comprises a front panel 420 and a back panel 430, both made of absorbent material, preferably the Suitable material for fluid storage. Figure 5 further shows a central section 451 of the absorbent material covering the front and rear panels 420 and 430. The material of this central section 451 comprises a fluid distribution material having vertical flow characteristics as discussed above, or a material that has the distribution and storage properties required. The central section 451 may comprise multiple strips of absorbent material, each having individual characteristics of shape, width, length and thickness. For example, in a preferred embodiment, a resilient, flexible, relatively thin, polymeric foam strip 451 is preferably made from the same fluid distribution / storage material as the front and rear panels 420 and 430. Also depicted in FIG. Figure 5 is an acquisition material 452.

TEST METHODS A. TOTAL ABSORBENT CAPACITY OF THE ARTICLE AND% CAPACITY OF THE REGION OF THE ENTREPIERNA The following protocol is intended to provide the Total Absorbent Capacity (TAC) as well as the Capacity of the Crotch Region (CRC) of the article. The protocol uses the data obtained from the test in use of the articles by juries.

Selection of the Jury The jury must be recruited by weight, within the range of size tried of the articles that are tested. Concurrently, the product sizes and the weight of the babies for the Pampers, Luvs and Huggies marketed are as follows (as of March 1997): A group of 100 juries should be recruited uniformly through the appropriate weight range relative to the size of article being tested and the user group attempted. Note: the above sizes are for concurrently marketed items and may change as the designs and / or sizes of the item are modified. Following the recruitment stage, 30 juries will be selected from the group at random.

Arrangement of the Articles The test articles are weighed to provide a dry weight of the article. The jury removes the article from the child he is carrying when the test begins, that is, the jury's own article, and the jury applies the test article, in the normal manner of jury. Once the test article is applied, the jury places the user in the standing position and the crotch point is determined as described above in the present application. The crotch point is then marked out of the test article in a permanent manner. The loading area is then determined by measuring from the crotch point forward to the appropriate genital point in relation to the sex and size of the user. The forward distance of the crotch point for women in the medium size is 1.25 inches. The forward distance from the crotch point for men in the median size range is 2.5 inches. It is apparent to an expert in the art that these distances may increase or decrease with the size of the user. Therefore, for the other sizes, the distance can be determined by placing the user in a standing position and determining the crotch point as previously specified, and then measuring from the crotch point to the urethra or base of the penis. Once the loading area is determined, the distance from the front waist to the loading area is measured; this distance is used to establish the length of the loading tube to be inserted into the article during the loading of synthetic urine.

Synthetic urine The test fluid used for the test is synthetic urine (syn-urine). This aqueous composition comprises the following components dissolved in distilled water: The temperature in the urine-syn bath will be maintained at 37 ° C. A suitable heating bath is the Lauda M20-B available from VWR Scientific Products. Supply pumps will be used to pump urine-syn from the hot bath to the item. The volume and delivery regime will be from 75 ml to 15 ml / second. Suitable pumps include the Masterflex 7550-60 or 7524-00 models available from the Colé Parmer Instrument Company. The internal diameter of the loading tube is 0.125 inches.

Protocol Once the items are applied and marked as described above, loose-fitting blue cotton pants are weighed to provide heavy dry pants and then the pants are applied over the test article in such a way that they are identified and measured easily leaks. The test items are then loaded by inserting the loading tube at the predetermined distance, as measured from the waist, and applying the specified load to the specified rate.

Between charges, the user returns to normal activity. The items are loaded with the specified load and rate every 10 minutes, that is, 10 minute intervals between charges. These charges are continued until approximately 1 gram of fluid leaks from the article onto the cotton pants. This can be determined by removing the pants and weighing them. Once at least 1 gram of fluid has leaked onto the pants, the test article is removed and is immediately weighed.

Total Capacity and Capacity of the Crotch Region The total capacity for a given test item is determined by subtracting the weight of the dry item from a given item from the weight of the wet item of that same item. The total capacity for the group is the average of the total capacities of the individual items. The capacity of the crotch region is determined by placing the loaded item flat and trimming the crotch region of the article. (The crotch region is determined in relation to the crotch point, which was previously identified for the article.) This region is then weighed. This procedure must be conducted within 15 minutes of the removal of the user's item. A corresponding crotch region is cut from a dry article to provide a dry weight of the crotch region. The crotch capacity is determined by subtracting weight from the dry crotch region from the weight of the wet crotch region. This provides the crotch capacity for a given item.

The capacity of the crotch for the group of articles is considered to be the average of the individual capacities of the crotch region. The capacity of the crotch region as a percentage of the total is determined by dividing the average capacity of the crotch region by the total average capacity for a given group of items. A similar procedure is used to determine the percentage of the absorbent capacity of the absorbent core behind the crotch point.

B. ACQUISITION OF FLUID The fluid acquisition method provides a means for introducing fluid into an absorbent article that simulates conditions of use. The item will be loaded with 70% total absorbent capacity. Certain of the other Test Methods described below will use a wet article according to this method for characterization according to the present invention.

Principle This test simulates the introduction of urine into an article under the following conditions: 1) A pressure of 0.4 psi (approximately 28 g / cm2) is applied to an article sample. 2) Synthetic urine is introduced into the article in increments of 50 ml / load at a rate of 10 ml / sec, with a time period of 15 minutes (equilibrium time) between each load. The number of charges will be dictated by the total absorbent capacity of the article.

Environment Conditioned Apparatus: Controlled temperature and humidity within the following limits: Temperature 88 +/- 2 ° F Relative Humidity: 50 +/- 2% Acquisition Tester: Obtained from Concord - Renn Co., 6315 Warick St., Cincinnati, Oh, 45227 Test Base Part (PLEXIGLÁS) Foam Base - 6"x 10" x "foam covered with polyethylene backsheet material - type of foam: Density 1.0 Ibit / ft3 IDL 24 Psi Nozzle Cover Plate Graduated Cylinders: VWR Scientific , (100 ml) Catalog number: (100 ml) (1,000 ml) 24711-310 (1, 000 ml); Catalog number: 24711 - 364 or equivalent Erlenmeyer flask: VWR Scientific Catalog number: 29135-307 or ( 6,000 ml) Equivalent Digital Pump: Cole-Parmer Instrument Co .; Tei No. (800) 323- 4340 Catalog Number: G-07523-20 Easy Charge Pumping Head: Cole-Parmer Instrument Co .; Catalog: G-07518-02 Distilled Water: Convenient Source Synthetic Urine: Urine-Syn as prepared in Section A of the Test Methods.

Assembly of the Test Apparatus The test apparatus must be assembled as shown in Figure 6. The test apparatus is designated by the reference number 520. The test apparatus 520 is placed on a suitable table or on the upper part of the test apparatus. a bank. The test apparatus 520 comprises a synthetic urine dispenser 524, a pump 528, a pair of electrical connectors (or probes) 536, and a sample holder 546. The pump 528 is a volumetric pump that is equipped with a pump head 530 and a digital timer 532. The electrical probes 536 are connected to the pump 528 via the cables 538. The Tygon® tube 540 runs from the synthetic urine supply tube 524 to the pump 528 and from the pump 528 to the fastener Sample 546. The Tygon® tube 540 running from the pump 528 to the sample holder 546 is preferably held on the sample holder 546 by a ring holder (not shown). The end of the Tygon® tube 540 running from the sample holder 546 to the sample holder 546 also contains a nozzle 542 for directing the synthetic urine on the test sample. The sample holder 546 comprises a PLEXIGLÁS test layer, a foam base 550 and a cover plate 552. The test layer 548 is shown schematically in Figure 6 as comprising a PLEXIGLÁS base plate for simplicity. Test layer 548 must also have four PLEXIGLAS walls that are vertical from the base and surround diaper sample 510. This prevents synthetic urine from leaking out of test layer 548 during the test. The 550 base foam is placed on top of the PLEXIGLÁS 548 base plate in such a way that the pressure on the sample will be equalized during the test. A diaper sample is placed on the foam base with its top sheet facing up. The cover plate 552 is then placed on top of the diaper sample in such a way that the cylindrical column directing the liquid 556 and the opening 558 in the cover plate are in the transverse center of the diaper sample. Then weights 560 are placed on the cover plate 562 in such a way that a pressure of 0.4 psi is applied to the diaper sample. The electric probes are then arranged in such a way that they barely touch the upper sheet of the diaper sample in the region where the synthetic urine is deposited. The electric probes are located on the outside, and on opposite sides of the cylindrical column directing the liquid 556. The electrical probes 536 detect the presence of synthetic urine on the upper sheet of the diaper sample. When all the synthetic urine has been acquired by the diaper sample, it interrupts the electrical connection between the electrical probes 536.

Procedure 1) Trim any elastic from the test diaper in such a way that the diaper lies flat. Place the diaper over the top of the foam piece on the base of the acquisition tester. The diaper should be placed with the top sheet of the diaper facing up, such that the synthetic urine will be applied to the top sheet. The diaper should be placed in such a way that the urine supply nozzle is approximately 3 inches from the front edge of the diaper. 2) Place the assembly on the cover plate on the diaper. 3) of gently placing the appropriate weights on the cover plate in such a way that a pressure of 0.4 psi is applied on the diaper. 4) move the ring support to the position so that the nozzle is directly above the center of the cylindrical column that directs the liquid. Lower the ring until the nozzle extends 2 inches (approximately 5 centimeters) above the diaper surface. Place the nozzle that is perpendicular to the top of the bench in such a way. 5) start pumping 6) the pump will begin to supply the specified volume of synthetic urine, and the timer will be running until the volume has been absorbed by the diaper. 7) After the fluid has been absorbed, the confining pressure is removed, leaving the cover plate in place, for a period of five minutes. The confining pressure is then reapplied for the remaining 10 minutes of the equilibrium time. 8) After the equilibrium time of 15 minutes has elapsed, the test cycle will be automatically repeated. The test cycle will run the number of times desired in such a way that a specific volume of synthetic urine is applied to the diaper sample. 9) After completing all the tests, distilled water is run through the tube. The surface of the small test contacts located inside the base of the upper plate tube is cleaned with a small brush on a daily basis. If the acquisition tester is being used around the clock and it is not possible to rinse the synthetic urine from the tube, replace the tube monthly. Replace the foam base every three months to maintain the firmness of the support.

C. WATCH WIDTH WHEN WET AND DRY TRANSVERSAL SECTION AREA The width of the crotch of an absorbent core of an absorbent article is measured by first determining the crotch point of the absorbent article. The article is then wet to 70% of its total capacity according to the fluid acquisition method. The item removed from the appliance and allowed to reach equilibrium for one hour. When equilibrium occurs, the article is cut transversely across its thickness to provide a 2-inch long section, where the crotch point is at the cross-sectional and longitudinal center of the section. Each of the wet layers of the sectioned sample is then weighed. The width of the layer that contains most of the absorbed fluid corresponds to the width of the crotch of the absorbent core. Once the above determination of the absorbent core layer retaining most of the fluid has been made, a dry article is cut transversely by the preceding paragraph. The previously determined layer that retains most of the fluid is separated from the other components of the absorbent core and the dry gauge and width are determined (the gauge is measured under a confining pressure of 0.2 psi.) When this layer consists of a plurality of discrete layers, the width and the gauge of each of the layers is measured and the sum of their individual cross-sectional areas corresponds to the cross-sectional area of the crotch region of the absorbent core.

D. PROOF OF FLOW OF CAPILLARY ABSORPTION OR EFFECT OF DATE VERTICAL Apparatus Synthetic urine container (prepared as described in section A of the Test Method) with sufficient volume such that the fluid collected does not cause more than a 1 cm drop in fluid height.

Electronic balance to monitor the loss of fluid from the container during the experiment. Environmental chamber or other means to raise the relative humidity to reduce the evaporation of the fluid during the experiment.

Protocol Cut the test strip to 5 cm in width and 30 cm in length using a medium (for example, razor knife) that does not densify or shatter the cut edges. The length of the strip must be long enough so that the front part of the fluid does not reach the end of the strip after 60 minutes of! driving time by wicking effect. Measure the gauge (thickness) of the test strip at a minimum of three places along the length of the strip. The average gauge of the strip is the average of 3 (or more) gauges measured, in units of cm. Place the fluid reservoir on the electronic balance and tare the balance. Suspend the test strip above the fluid so that it hangs vertically. (for materials that lack sufficient integrity to withstand the test protocol, a hydrophobic screen that does not impact the performance of capillary absorption can be used to hold the material.) Lower the strip in the fluid so that 2 cm of the strip is immersed in the fluid. Monitor the weight loss of the fluid reservoir against time for a total of 60 minutes. Determine the admission or uptake of fluid by dry cross-sectional area by dividing the weight loss of the receptacle between the dry cross-sectional area of the test strip (i.e., 5 cm x the average gauge).

Graph the fluid uptake by dry cross-sectional area (units of g / cm2) against time (minutes). Calculate the curve of the curvature in 10 minutes and in 30 minutes. These numbers correlate to the incremental flow value at 10 minutes (IF10) and the incremental flow value at 30 minutes (IF30), respectively.

Claims (11)

1. An absorbent core having a crotch region, characterized in that (i) the crotch region has an absorbent capacity not greater than 40% of the total absorbent capacity of the absorbent core and (ii) the crotch region comprises a material that it has an IF10 value of at least 0.5 g / cm2 / minute. .

2. The absorbent core according to claim 1, characterized in that (i) the crotch region of the absorbent core has an absorbent capacity not greater than 25% of the total absorbent capacity of the absorbent core, preferably not greater than 15% of the capacity total absorber of the absorbent core, preferably from 0 to 10% of the total absorbent capacity of the absorbent core, and (ii) the material has an IF10 value of at least 0.8 g / cm2 / minute, preferably at least 1 g / cm2 / minute, preferably at least 2 g / cm2 / minute.

3. An absorbent core having a crotch region, characterized in that (i) the crotch region has an absorbent capacity not greater than 40% of the total absorbent capacity of the absorbent core and (ii) and the crotch region comprises a material having an IF30 value of at least 0.3 g / cm2 / min. -

4. The absorbent core according to claim 3, characterized in that (i) the crotch region of the absorbent core has an absorbent capacity not greater than 25% of the total absorbent capacity of the absorbent core, preferably not greater than 15% of the capacity total absorbent of the absorbent core, preferably from 0 to 10% of the total absorbent capacity of the absorbent core, and (ii) the material has an IF30 value of at least 0.4 g / cm2 / minute, preferably at least 1 g / cm2 / minute, preferably at least 1.5 g / cm2 / minute.

5. An absorbent core having a crotch region, characterized in that (i) the crotch region has an absorbent capacity not greater than 40% of the total absorbent capacity of the absorbent core and (ii) the crotch region comprises a material having an IF value of at least 0.5 g / cm2 / minute and an IF30 value of at least 0.3 g / cm2 / minute. The absorbent core according to claim 5, characterized in that (i) the crotch region of the absorbent core has an absorbent capacity not greater than 25% of the total absorbent capacity of the absorbent core, preferably not greater than 15% of the absorbent core. the total absorbent capacity of the absorbent core, preferably from 0 to 10% of the total absorbent capacity of the absorbent core. An absorbent core according to any of claims 1 to 6, characterized in that the crotch region comprises an open cell absorbent polymer foam material having a specific surface area value per foam volume of at least 0.025 m2 / cm3. The absorbent core according to claim 7, characterized in that the absorbent polymer foam material has a specific surface area value per foam volume of at least 0.05 m2 / cm3, preferably at least 0.07 m2 / cm3. The absorbent core according to claim 7, characterized in that the open cell absorbent polymeric foam material has a resistance to compression deflection of 40% or less when measured under a confining pressure of 0.74 psi, preferably from 2% to 25% when measured under a confining pressure of 0.74 psi., preferably from 2% to 15% when measured under a confining pressure of 0.74 psi. The absorbent core according to claim 7, characterized in that the open cell absorbent polymeric foam material has a capillary absorption pressure of at least 24 cm, preferably at least 30 cm. 11. An absorbent article comprising the absorbent core of any of claims 1 to 10.