MXPA99008878A - Absorbent articles providing improved fit when wet - Google Patents

Abstract

Disclosed are absorbent cores for inclusion in absorbent 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 to be relatively narrow in the crotch region of the article, 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. The invention particularly relates to an absorbent article comprising an absorbent core wherein the absorbent core has a crotch width when dry and when wet of not more than about 7 cm, and wherein the crotch region of the absorbent core has a capacity of not more than about 40%of the absorbent core's total absorbent capacity.

Description

ARTICLES TO SORBENTS THAT PROVIDE IMPROVED ADJUSTMENT WHEN MOJAN FIELD OF THE INVENTION The present invention relates to absorbent structures useful in absorbent articles! such as diapers, incontinence briefs, training pants, diapers and diaper liners, sanitary ware, and the like. More particularly, the invention relates to absorbent structures that provide articles that have improved fit when wetted with body fluids.

BACKGROUND OF THE INVENTION The > ebés and other incontinent individuals wear in 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, as well as to isolate these materials from the user's body and from the garments and bedding of the users. Disposable absorbent articles having many different basic designs were known in the art. For example, United States Patent Re. 26,152, entitled "Disposable Bag" issued to Duncan and Baker on January 31, 1967, describes a tessechable diaper that has achieved wide acceptance and commercial success. U.S. Patent No. 3,860,003 entitled "Shrinkable Side Portions for Understanding These Absorbent Gstructures." 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 combination with the invention. with the drawings that accompany it.

BRIEF DESCRIPTION OF THE INVENTION The present invention provides absorbent structures for intrusion into absorbent articles such as diapers, incontinence briefs, training shoes, diaper pads and liners, feminine hygiene garments, and the like, designed to provide improved fit and comfort. for the patient while adequately containing body exudates. This absorbent article has a containment assembly (chassis) typically comprising a liquid-permeable upper sheet and a liquid impervious back sheet, and an absorbent core associated with the outer cover layer. The absorbent core is designed to be made relatively narrow and the crotch region of the diaper, even when the core absorbs significant amounts of fl uid during use. To achieve this, the absorbent core is designed so that the fluid is moved substantially from the crotch region toward the front and / or rear regions of the article. The disclosure is particularly related to an absorbent article comprising an absorbent core, wherein the absorbent core has a crotch width when dry and when it is wet no more than about seven centimeters, where the crotch region of Absorbent core has a capacity not may > r of approximately 40% of the total absorbent capacity of the absorbent core «• BRIEF DESCRIPTION OF THE DRAWINGS While the description concludes with the claims pointing out in a particular manner and claiming in a different manner the subject matter that is considered as subject 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 drawings that correspond to it, in which they use similar designations to designate substantially identical elements, and in which: The fi. lura 1 is a top plan view of an absorbent article according to the present invention wherein the top sheet is transparent to more clearly show the absorbent fiber; Fluid 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. Relia 5 is an exploded perspective view of a multi-piece absorbent core useful in the present invention; and The fineness 6 is a schematic view of the apparatus used to load items 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 those that should be noted that the members, layers, and structures of the absorbent articles according to the pre > The invention may or may not be generally planar in nature, and may be formed or profiled in any desired configuration. A length of an absorbent article in the form of a diaper 20 having an absent core in accordance with the present invention is Figure 1 is a top plan view of the diaper 20 in a flattened, non-contracted state (i.e. with any contraction induced by the removed elastic) having a supersheet 22, a back sheet 24 , and an indicated absorbent core generally eats 28 which is positioned between the upper sheet 22 and the back sheet 24. The upper sheet 22 is shown as being transparent to better illustrate a! absorbent core 28 Com is also shown in Figure 1, diaper 20 has a front waistband region 32, a posterior waistband region 34, a central region 36 and a periphery 38 that is defined by the outer edge of the back sheet 24 and which has longitudinal edges designated 40 and end edges designated 42. The longitudinal axis of the diaper 20 with 3 essentially parallel to the longitudinal edges 40 and is represented as the longitudinal centerline 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 center line 66 (and corresponds to the X or anch direction)." The waistband regions 32 and 34 comprise those upper portions of the pan >20, which when worn, surround the user's waist, the central region 36 and that part of the diaper 20 between the waistband regions 32 and 34, and comprises the part of the diaper 20 which when worn, is placed between the legs of the wearer and covers < the lower torso of the user. In this manner, the central region 36 defines the typical liquid deposition area for a diaper 20 or other disposable absorbent article.

The superior a 22 and the back sheet 24 can be mutually associated in any suitable J-way. As used herein, the term "associated" encompasses the configurations where the top sheet 22 is attached directly to the back sheet 24 by attaching the top sheet directly to the back sheet, and the dor shapes of the top sheet are attached indirectly to the posterior sheet by fixing the upper sheet to intermediate members which the sucres are fixed to the posterior sheet. Preferably, the upper web 22 and the rear web 24 are fixed directly to each other by joining means (not shown) such as an adhesive and any other attachment means as is known in the art. For example, a uniform, continuous adhesive layer, a patterned adhesive layer, or a line array or separate adhesive spots can be used: to attach the topsheet 22 to the backsheet 24. As shown in Figure 1 , the upper sheet 22 has a slightly smaller size configuration than the rear sheet 24.}. However, the topsheet 22 and the sheet 24 can both have the same size 5nn (ie, be coextensive) so that they mutually join at the rim 38 of the diaper 20. The size of the backsheet 24 it is dictated in part by the size of the absorbent core 28 and the exact design of the selected diaper. In I; modality shown in Figure 1, the back sheet 24 has a configuration in hourglass setting. However, other configurations such as rectangular, I-shaped and the like are also suitable. When not shown, the diaper 20 may have elastic members that exert a contraction force on the diaper in such a way that it more closely fits and comforts the wearer. These elastic members can be assembled in a variety of well-known configurations, such as those generally described in United States Patent No. 3,860,003 (Buell), issued on 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 and itros), issued May 7, 1985, which is incorporated by reference. The elastic members are secured to the diaper 20 in an elastically contiguous condition such that in a normally unrestricted configuration, these elastic members contract or pick up the diaper 20. The elastic members may be secured in an elastically collapsible condition at At least two manens. For example, the elastic members can be pulled and secured as long as the diaper 20 is in a non-contracted condition. Alternatively, the diaper 2j may be contracted, for example, by pleating, and the elastic members secured and connected to the diaper 20 while in its unstressed condition the süh stretch. The elastic members can essentially extend the total length of the sheet 20 in the central region 36, or alternatively they can extend the total length of the sheet 20, or any other suitable length to provide a stretchable elastic 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 shown in an "I" configuration. As indicated above, the absorbent core will comprise frontal and posterior regiojhes, as well as a crotch region. These regions are deflated by determining the crotch point of the core 28 according to the description here. As discussed above, the crotch point is determined by reference to the user's anatomy. For purposes of illustration only, the crotch puncture of the core 28 is represented as the article 27 thickness from about 0.012 millimeters to about 0.051 millimeters. In one preferred embodiment of the present invention, at least a portion of the back sheet is subjected to mechanical stretching for the purpose of providing both a stretch laminate with "zero deformation" which forms the side panels and, if it is desired to predefine the part of the back sheet that coincides with the elastic waist feature or any other elastic feature. In this way, the backsheet is preferably stretchable, very preferably estSable, but not necessarily elastomeric, such that the backsheet will be, at or; urrir the mechanical stretching, for less elongated to a degree of permanent way] in such a way that it will not return totally to its original configuration not distorted. In preferred embodiments, the backsheet can be subjected to mechanical stretching without undue rupture or tearing. In this way, it is preferred that the poster sheet has an elongation before final rupture of at least about < 00% to about 700% in the machine's transverse direction as they use the method consisting of ASTM D-638. Therefore, the polymeric films preferred for use as the backsheet have a high linear polyethylene content of low density. Particularly preferred materials for the poster sheet include mixtures 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 Trecjegar Industries, Inc. of Terre Haute, Indiana, under the designations X-8323, RR8220 p / ez of certain blown films, and RR5475 mixture for certain cast films . The backsheet 24 is typically embossed which (typically, still caliper of approximately 0.127 mm) and / or Herminio to dull to provide a m-like appearance. In addition, the back sheet can allow that article and its absorbent core. Referring to Figure 4, the legs of a standing user are i represented in cross-sectional manner as 301 and 302. A continuous material 303 (eg, a rubber band or band) is twisted once and is placed or airing the user's legs at a point sufficiently close to the user's torso 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 as such, and the crotch region of the core is determined by the above description. The width of the crotch of the absorbent core at the crotch point, when it is dry and when it is wet, is important when providing improved adjustment in the user. It is preferred that the width of the crotch be small, even when sheeting with the fluid, such that the absorbent core suffers minimal swelling or 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 wet they are no more than about seven centimeters. Preferably, the [width of the crotch when you are dry and when it is wet will not be greater than about six centimeters, even more preferably not more than about neo centimeters. The means for measuring the width of the crotch is described in the section on Test Methods, infra. As it pertains to the problem of bulging during use, the width of the crotch may be more relevant than the cross sectional area e < n the core crotch point. It is found that a reduction in the width of the crotch of an absorbent core with a uniform capacity per unit of surface area necessarily reduces the amount of material and 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 as to increase the capacity per unit area i r equilibrium in the core crotch re ion. In certain embodiments, the absorbent core will be cemented such that most of the fluid absorbed (ie, more than 50%) will eventually be stored behind the crotch point of the core. Preferably, p > At least 67% of the total absorbent capacity of the absorbent core will be behind the point between the core leg. A method for determining the total absorptive capacity of the core and the percent of the capacity of the crotch region of the numeral 30 is described in the Test Methods section below. Com > discussed above, the absorbent core will comprise a material that functions to distribute the fluid out of the region of between the core leg. The capillary absorption vd rtical, that is, the capillary absorption of the fluid in an opposite direction of the force of gravity, is an attribute of operation especially desirable for the material of distri > ution. The dispensing material will be used frequently in absorbent articles in such a way that the fluid that is absorbed must be transferred into the article from a relatively lower position to a relatively higher position within the core of the article. Accordingly, the ability of these materials to capillary absorb the fluid against the forces of gravity is particularly relevant to their operation as the absorbent materials in the articles herein. The characteristics of capillary absorption or wicking that are particularly important for the distribution of fluid are: A) the coefficient of capillary v-rtical absorption of the fluid through the distribution material; and B) the absorbent capacity of the distribution ma- terial at specific heights of capillary absorption. Another important feature of the distribution material is the ability to drain (distribute) the fluid from the concurrent absorbent structures (eg, the acquisition materials) with which the material may be in contact. The insufficient cd of capillary absorption. vertical 3 determined by the measurement of the time taken for a test colored liquid (eg, synthetic urine) inside a tank to absorb c-pillarly a vertical distance of five centimeters through a test strip of material of specific size . The vertical capillary b sorption process is described in greater detail in the TEST METHODS section of U.S. Patent No. 5,387,207, but is performed at 31 gr, two centigrade instead of 37 degrees centigrade. To be especially useful in absorbent articles for absorbing urine, the distribution material will absorb capillary synthetic urine (65 + - 5 dynes / cm) at a height of five centimeters in no more than about 30 minutes. More preferably, the dispensing material will capillary the synthetic urine at a height of five centimeters in no more than about 15 minutes, even more preferably in no more than about c neo minutes. In another preferred embodiment, the distribution material will absorb the synthetic urine at a height of two centimeters in no more than about > s minutes The pipet of the absorbent capacity by vertical capillary absorption measures the amount of the fluid per sample of the distribution material that is maintained within each vertical section of 2.54 centimeters of the same sample of standard size used in the capillary absorption test. vertical. This determination is generally made after the sample has been allowed to vertically absorb the test fluid at equilibrium (eg, after about 18 hours). The vertical capillary absorption absorbent cape test is described in more detail in the TEST METHODS section of U.S. Patent No. 5,387,207. In a preferred embodiment, the absorbent core useful in the articles of the present invention will comprise a fluid distribution material having a capacity of abscission. vertical capillary action of at least approximately 15 g / g, L vitrea transition. Ui i Tg represents the midpoint of the transition between the vitreous and rubber 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 prog. You see the fracture. When these foams are collapsible, these also typically take a long time to recover to the expanded state when they get wet Q D? Aqueous fluids colder than the Tg of the polymer after being stored in the collapsed state for prolonged periods. The desired combination of mechanical properties, specifically strength and resilience, typically requires 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. In addition, this trend is important for the ability of the foam to provide the vertical capillary ablation capabilities discussed here. See United States Patent No. 5,387,237, where it was discussed in detail in the specific surface area by volume of foam. "Specific surface area per volume of foam" 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 which are empirically permeable in a collapsed state, and are therefore preferred here. Another important property of the absorbent polymer foams useful herein is S-free absorbent capacity. The "absorbent free capacity" is the total amount of the test liquid (synthetic urine) that a sample of foam given saturated foam 1 maintained under a certain confining pressure for a specific temperature and period of time. The method for performing this particular type of test is disclosed in the TEST METHODS section of application 866. Useful nonabsorbent foams are those exhibiting an RTCD such that a confining pressure of 5.1 kPa produces an effort or tension of typically about 0% or less of compression of the foam structure when it has been saturated. This is its free absorbent capacity with synthetic urine, having 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 10%. Foam dies, and especially cells which are formed by polymerizing a fasj 3 of oil 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 foam sample 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, in determining the cell size of the foams involves a simple measurement based on the micro-scanned photograph of a foam sample. The cell size measurements given in a present 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 one complementary to the other. In a preferred execution, the untreated web is directed by the idler rolls to pass between the ridges and grooves of the surface of a higher corrugated roll, and the respective internal gear slots and grooves of the surface of a corrugated strip below . Although the exact configuration, spacing and depth:] of the complementary ridges and grooves on the upper and lower corrugated rollers J / will vary, depending on factors such as the amount of tensioning desired in the work and the properties of the frame itself, such as basis weight and resilience, a specific preferred embodiment has an essentially rectangular profile, whereby (such as by the treatment of a web having a basis weight of about 150 grams per square meter and a starting gauge of about .5 mm) the slots have a width of 1 mm, the projections have a width 36 of 0.6 mi, a distance from the bottom of the slots to the peaks of the resa als of approximately 8 mm, and a radio flattened from -about 0] 1 millimeters For frames that have different properties, these dimensions must be appropriately adopted, which is found to be advantageous to have an of the rests to be between 30% and 90% of the width of the slots ", preferably in 50% 70%. The widths of the grooves must be related to the size of the treated fabric, and not be outside the range of 40% to 100% of the size, preferably from 60% to 80%. The gr; The overlapping of the opposite peaks in the corrugated rollers can, of course, be adjusted, as desired, to produce more or less robust mechanical treatment in the triad. The maximum speed is dictated by the limitations of operation, such as the operation of the equipment effectively, and by the properties of the material, which could result in the perforation or cutting of the weft in a very severe treatment. . It is found that this overlap should not exceed 80% of the gauge of the weft, preferably not greater than 33% of the gauge of the weft, and even more preferably not greater than 25% of the gauge. defined by the limitation that the plot is actually treated mechanically. This requires that the distance of the corrugated rollers, which are c Isposed in such a way that they can mesh internally if the distance would be narrower, is smaller than the caliber of the weft. Then, the "overlap" as used herein is less than 0, and the lower limit of overlap that is useful for the present invention is about -100%. Preferably, however, the overlap must be greater than -15% and more preferably greater than + 5%. A particularly desirable value for an overlap to treat a plot of 150 grams per square meter and a caliber of 1.5 millimeters has been found to be + 13%. The materials of the corrugated rolls can be any suitable material to allow the proper formation and to resist the pressure exerted by the rollers on the material such as metal such as aluminum or steel alloys. In the case of very low friction or high nuy between the weft and the rollers, the surface of the roller can be roughened or smoothed or otherwise treated to prevent the weft from sliding between the corrugations or it will prevent it from penetrating in a Sufficient in the corrugations, It is also recognized that while the preferred embodiment comprises a pair of rollers c < When the corrugations have their corrugations substantially aligned with one another, the process can also employ corrugated roll walls, where the corrugations are not all oriented parallel to each other. In addition, the corrugation on these pairs of corrugated rolls need not be necessarily aligned parallel to any of the machine. For example, if a curvilinear fluid distribution path is deflected, the gear teeth on the corners of the corrugated rollers used for stretching and others), issued on February 28, 1978, and the United States Patent. United States No. 4,062,817 (Wej terman), issued December 13, 1977, both incorporated herein by reference. The olefinically unsaturated carboxylic acid and carboxylic acid anionic acid ions include acrylic acids illustrated by the same acrylic acid, methylmeric acid, ethacrylic acid, α-chloroacrylic acid, α-cyanoacrylic acid, β-methacrylic acid, crotonic acid ), α-phenylacrylic acid, β-acryloxypropionic acid, sorbic acid, cc-cl acid > rosorbic, angelic acid, cinnamic acid, p-chloro cinnamic acid, β-esterylacrylic acid, itaconic acid, citroconic acid, mesaconic acid, glutaconic acid, iconic acid, maleic acid, fumaric acid, tricarboxyethylene and maleic acid anhydride. The olefinically unsaturated sulfonic acid ionomers include vinylsulfonic acids > s aliphatic or aromatic such as vinyl sulphonic acid, allyl sulfonic acid, inyl toluenesulphonic acid and styrene-suleyonic acid; acrylic and methacrylic acid, such as sulfoethyl acrylate, sulphoethyl methacrylate, sulfopropyl acrylate, sulfopropyl methacrylate, 2-hydroxy-3-methacryloxypropylsulfonic acid and 2-acrylamide-4-methylpropan-suphonic acid. Preferred hydrogel-forming absorbent Dolimers for use in the above invention contain carboxy groups. These polymers include starch-acrylonitrile hydrolyzed copolymers, partially starch-acrylonitrile graft copolymers, starch-acrylic acid graft copolymers, partially neutralized graft copolymers of starch-acrylic acid, saponified copolymers of vinyl acetate-acrylic ester, hydrolyzed acrylonitrile or acrylated copolymers ] lida, polymers slightly intertwined in the network structure of any of the c >previous polymers, partially neutralized polyacrylic acid, and Adhesion, edited by Robert F. Gould (Copyright 1964). A fiber, or the surface of a fiber, is said to be wetted by a fluid (ie, hydrophilic), when either the angle of contact between the fluid and the fiber, or its surface is less than 90 °, or when The fluid will spontaneously disperse through the surface of the fiber, both with co-existing coexisting normally. Conversely, a fiber or surface is considered to be hydrophobic if the contact angle is greater than 90 ° and the fluid is not spontaneously spreading across the surface of the fiber, for useful storage materials Here, 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 hydrophobic fibers, such as thermoplastic fibers treated with surfactant or treated with silica, are derived from, for example, polyolefin such as polyethylene or polypropylene, polyacrylics, polyalides, 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 wood pulp fibers from soft southern woods, due to their excellent absorbency characteristics. These wood pulp fibers can also be obtained from mechanical processes such as soil level processes, refined mechanical pulp processes, thermomechanical-chemical mechanical and chemical-thermomechanical processes. Recycled or secondary wood pulp fibers as well as bleached and unbleached wood pulp fibers can be used.

I presented. These fibers, and the processes to elaborate them, are described in the previously incorporated patents. Tale hardened fibers that are twisted and curled can be quantified by referencing ambüs, a "twist count" of fiber and a "curl factor" of the fiber. As used herein, the term "torsional count" refers to the number of torsional nodes present at a long fiber length. The torsion count is used as a means to measure the rate at which the fiber is rotated around its longitudinal axis. The term "torsion 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 darkly relative to the rest of the fiber. fiber when viewed under the microscope with transmitted light The torsional knot appears dark at locations in which transmitted light passes through an additional fiber wall due to the aforementioned rotation. The disjunction between the knots corresponds to an axial rotation of 180 °. The number of knots and torsion in a certain length of fiber (for example the torsion count) is a direct indication 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 torque count tq: a are described in U.S. Patent No. 4,898,642. The preferred hardened fibers will have an average dry fiber twist count of less than about 2.7, preferably about 4.5 twists, knots per millimeter, > . In addition, the average wet fiber twist count of these preferable fibers is at least about 1.8, preferably at least about 3.0, and should preferably also be at least about 0.5 knots per millimeter less than the average dry fiber torque count. Even more preferably, the average dry fiber torque count should be at least about 5.5 ni. two torsion per millimeter, and the average wet fiber torsion count must be at least 4.0 knots per millimeter and must also be at least 1.6 knots per millimeter less than your dry fiber torsion count average] More preferably, the average dry fiber twist count should be at least about 6.5 knots per millimeter, and the average hydrodynamic fiber torsion count should be at least about 5.0 knots per twist. millimeter or and must also be at least 1.0 knots per millimeter less than the average dry fiber twist count. In addition to being twisted, these preferred hardened fibers are also crimped. The fiber curl can be described as the fractional shortening of the fiber due to curls, orsions and / or curvature in the fiber. For the purposes of the present invention, the curl of the fiber is measured in terms of a two-dimensional plane. The extension of the curling fiber can be quantified by referring to a fiber curl factor. The fiber curl factor, a two-dimensional measure 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 given as the longest dimension of a two-dimensional rectangle surrounding the fiber, LR, and the current length of the fiber, A. Then , the fiber curl factor can be calculated by the following equation Curl factor = (LA / LR) - 1.

An image analysis tool 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 at least about 0.30 and more preferably dye a curl factor of at least about 0.50. This chemically hardened cellulosic fibers have certain properties that make them particularly useful in certain absorbent members according to the present invention., relative to non-hardened cellulosic fibers. In addition to being hydrophilic, these hardened fibers have unique combinations of hardness and resilience. This allows that the thermally bonded absorbent structures made with these fibers do not have high absorbency levels, and exhibit a high expansion resilience response to wet expansion. In particular, the resilience of these fibers in ureides 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 storage material. preferred to practice the present invention comprises a polyurethane foam material derived from the EAFIs. These preferable materials will have sufficient absorption pressures to desorb the distribution material, thus providing reduced fluid storage in the region of the article's interior. However, as indicated, a simple material can workAs both the distribution material and the storage material in the present articles. The emulsions described above with reference to the distribution component of the present sorbent articles are also useful as the storage component of the articles. Particularly preferred are Dolapsable polymeric foam materials which, upon contact with aqueous fluids (in particular fluids to body fluids such as urine), can expand and absorb these fluids. This absorbent polymeric foam storage materials comprise an e. Non-ionic, flexible, hydrophilic, open-celled polymeric foam with interconnects as described in, for example, the US Patent U.S. No. 5,387.2) 7 (Dyer et al.) Issued on February 7, 1995, and the copending 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. As discussed above, foam materials useful for providing the required fluid distribution outside the crotch region may also function to retain the fluid absorbed. However, as indicated, a simple material can function as both distribution and storage material in the present articles. The foam storage material useful in the present invention provides very low density absorbent spills. For a given expanded thickness, these lower density spills use the capacity of the polymeric material more efficiently. As a result, the low density absorbent foams provide an economically attractive method for achieving thinner absorbent cores for absorbent articles such as diapers, pads or 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 width of the crotch required (when dry or when wet) and the fluid retention values of the regiment. Do not overdo the crotch. As discussed above, to achieve both properties, it is preferred to have relatively little fluid storage in the trephine region. The absorbent lumens useful herein may comprise separate components for us < Rise in the crotch portions, front and back, of the absorbent core. Fig. 5 shows an exploded perspective view depicting the elements of an absorbent nip 428. As shown in Fig. 5, the absorbent core 428 corjgroups a front panel 420 and a back panel 430, both made of absorbent material. , preferably the material suitable for the storage of fluid. Figure 5 also shows a central section 451 of the absorbent material of Small Size Small / Medium Large Extra Size of the Large Medium Diaper Pampers Up to 10 8 - 14 lbs 12 - 18 lbs 16 - 28 lbs Above Ibs 22 lbs 27 lbs Luvs Na 8 to 14 Ibs 12 - 18 Ibs 16 - 28 lbs 21 - 37 Ibs Above 30 lbs Huggies Up to 10 8 - 14 lbs 12 - 18 lbs 16 - 28 lbs 22 - 37 Ibs Above lbs 30 Ibs.

A group of 100 juries should be recruited uniformly through the appropriate interval in relation to the size of the item being tested and the intended user group. Note: the above sizes are for concurrently commercialized items and may change as the designs and / or sizes of the item are modified. Depending on the recruitment stage, 30 juries will be selected from the group at: a: ar.

Arre lio of Articles Se | j roast the test items to provide a dry weight of the item. The judge 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 item, in the normal manner sworn. 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 PpHPtoto is then marked out of the test article in a permanent manner.

* The load zi &na is then determined by measuring from the crotch point towards the right genital point in relation to the sex and size of the user. The distance to the front of the crotch point for women in the medium size is 1.2 inches. The forward distance from the crotch point for men eg the median size range is 2.5 inches. It is for a person skilled in the art that these distances may increase or decrease with the size of the user. Thus, for the other sizes, the distance can be determined by placing the user in a standing position and determining the point of the intercourse as previously specified, and then measuring from the crotch point to the urethra or base of the penis. A rez that determines the loading area, 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.

Orín 1 Synthetic The test fluid that is used for the test is synthetic urine (syn-uriñe). 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. It is v; n to use supply pumps to pump urine-syn from the hot bath to the item. The volume and delivery regime will be 75 ml at 15 ml / second. Suitable bofnbas 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 A rez that items are applied and marked as described above, weigh loose blue cotton trousers to provide heavy dry trousers and then tighten the trousers over the test article in such a way that they identify and look at each other. 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 the loads, the user returns to his normal activity, Los; items are loaded with the specified load and rate every 10 minutes, ie, go] 10-minute intervals between charges. These loads are continued until approximately 1 gram of fluid leaks from the article onto the cotton pants. This can be determined by removing the bread and weighing it. A fez that at least 1 gram of fluid has leaked over the pants, the test item has been 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 item loaded flat and trimming the crotch region of the article. (The region of the intercourse 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 up dry weight of the crotch region. The crotch capacity is determined by subtracting weight from the sec crotch region of the weight of the wet crotch region. This provides the ability of the manager for a given article. The capacity of the crotch for the group of articles is considered to be e | average of the individual capacities of the crotch region, the capacity of the crotch region as a percentage of the total is determined by cfvidir the average capacity of the crotch region by the total average capacity for a given group of articles. . A similar procedure is used to determine the percentage of absorbent capacity of the absorbent core behind the crotch point.

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 o. {6,000 ml) equivalent Digital Pump: Cole-Parmer Instrument Co .; Tel No. (800) 323- 4340 Catalog Number: G-07523-20 Easy Load Pump Head: Cole-Parmer Instrument Co .; Catalog Number: 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 top of a bench. 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. i. synthetic The electrical 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 urine and intine 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 cells 536.

Procedure 1) Trim off any elastic from the test diaper in such a way that the diaper lies flat. Place the F añal on top of the piece of foam on the base of the acquisition tester. The diaper should be placed with the top sheet of the diaper facing upward, such that the synthetic urine will be applied to the top sheet. The diaper should be placed in such a manner that the urine supplying nozzle is approximately inches from the front edge of the diaper. 2) Place the erjlsamble on the cover plate on the diaper. 3) of placing the appropriate weights on the cover plate javemente in such a way that a pressure of 0.4 psi is applied on the diaper. 4) move ei s > Carry the ring 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 Doquilla extends 2 inches (approximately 5 centimeters) above the surface of the diaper. Position the nozzle that is perpendicular to the top of the barrel in such a way. 5) start pumping 6) the pump will start supplying the specified synthetic urine volume, and the stopwatch will be < n march 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 D. COEFFICIENCY OF VERTICAL CAPILLARY ABSORPTION AND CAPACITY ABSORBENT OF VERTICAL CAPILLARY ABSORPTION.

A vertical material absorption deficit of 5 centimeters and the ability to absorb vertical capillary absorption of the material for a given height are measured using the vertical capillary absorption coefficient test and the vertical capillary absorption capacity described in TEST METHODS section of the United States of America Pat. No. 5,387, 207 (Dyer et al.), which is incorporated > or reference, except at 31 centigrade instead of 37 degrees centigrade. For materials that lack sufficient integrity to withstand the prudential protocol, a hydrophobic screen can be used that does not impact the performance of capillary ibsorption to support the material. Finally, the step of washing and re-drying n the patent 207 is not carried out.

Claims (1)

1. rtical capillary absorption or wicking effect of at least 15 g / g at a height of centimeters; I preferred demented at least 25 g / g to a height of two centimeters; more preferably with less 40 g / g at a height of two centimeters. 7. The absorbent core according to claim 4 or claim 6, c < characterized in that the distribution material has a vertical capillary absortion absorbing capacity of at least 10 g / g at a height of 20 centimeters; more preferably at least 20 g / g at a height of 20 centimeters; more preferably at least 30 g / g at a height of 20 cm. The absorbent core according to any of claims 4, 3 or 7, characterized in that in the distribution material it has a vertical capillary absorption absorbing capacity of at least 5 g / g at a height of 25 centimeters; preferably at least 20 g / g at a height of 25 centimeters; more preferably at least 30 g / g at a height of 25 centimeters. The absorbent core according to any of claims 4, 7 or 8, characterized in that in the distribution material it has an absorbing capacity of vertical capillary absorption of at least 0.5 g / g at a height of 30 centimeters; Dreferred at least 10 g / g at a height of 30 centimeters; more preferably with less 20 g / g at a height of 30 centimeters. An absorbent core having a crotch width when it is dry and which is wet no more than seven centimeters, characterized in that the interpipe region of the absorbent core has an absorbent capacity not greater than 40% of the total absorbent capacity of the absorbent core. absorbent core; and characterized in that the absorbent core Domes a material selected from the group consisting of an open cell absorbent polymeric spherrf material; and a fibrous material comprising (i) coarse twisted and crimped, chemically hardened fibers, (ii) fibers of surface area chosen, and (iii) a chemical binder additive.