MXPA99008876A - Absorbent article having improved fluid acquisition performance - Google Patents

Abstract

Absorbent article comprising an absorbent core with a crotch region and at least one waist region, whereby said crotch region has a lower ultimate fluid storage capability than said at least one waist region. The article further has an improved fluid handling performance such as an acquisition rate of at least 0.6 ml in the fourth gush.

Description

ABSORBENT ARTICLE THAT HAS IMPROVED ACQUISITION PERFORMANCE OF FLUID Field of the invention The present invention relates to absorbent articles that are primarily designed to receive and retain bodily discharges such as - and primarily - urine. Such articles are disposable sanitary articles such as baby diapers, trainers, incontinence articles for Adults and the like.

Background of the Invention Absorbent articles for receiving and retaining bodily discharges such as urine or excrement, such as disposable diapers, trainers, incontinence articles for adults, are well known in the art, and significant effort has been devoted to improving their performance. Such improvements generally aim at directing the main function of such articles, that is to say the retention. of body fluids, but also in minimizing the drawbacks associated with the use of such articles increasing user comfort. Such improvements can mainly be classified to fall mainly into one of two categories: firstly related to "core technology", for example, "absorbency" in the broad sense of the word, or primarily related to "chassis technology". The first addresses how to collect and retain body waste (generally in some state of fluidity) in an "absorbent structure" (or core) where the waste material is acquired by the article (collection) and then stored (retained) , with a potential additional intermediate step of distribution (in particular of urine). The second category deals -generally- with the so-called "chassis elements", that is, the containment of body waste "within the limits of the article" - separating the absorbent structure (core) and the exterior, for example, the user's garments, etc., using a waterproof "top sheet"; or by preventing body exudates from escaping through the space between the absorbent article and the wearer's body, such as by elastic folds in the waist and leg openings. This also deals with the convenient application of the article to the user - such as by providing closure means such as tapes, and maintaining the article on the user, such as through arrangements such as belts always integrated within the application means. With this terminology, "comfort" for the user is currently being addressed by improving the elements of the chassis, adopting the elements of the diaper chassis to provide good "fit" of the article and to be soft and cushioned. PCT application WO 93/16669 (Alemany) or PCT application WO 93/21877 (Richasrdson) discloses disposable diapers, in which the comfort of the user is increased by introducing elastic characteristics such as allowing the best conformity of the body even if the user It is moving. When considering the impact of the cores on comfort, the general approach is to make it soft for use, non-irritating materials for the upper sheets or to minimize the thickness and / or volume of the dry article, preferably while maintaining the softness of the article. such nuclei. Recently, attempts have been made to also adopt the shape and shape of the absorbent structure to allow good fit.

Because materials called superabsorbents (or hydrogel-forming materials) have found wide application coverage in disposable absorbent articles, a number of products sold - such as PAMPERS sold by Procter & Gamble Co. or HUGGIES sold by Kimberly-Clark Corp. in several countries underwent a remarkable reduction in the thickness of the products. US-A-5,098,423 (Pieniak) discloses disposable diapers, which attempt to direct various "aspects" of comfort by providing structures of "low dry volume", claiming that not only the dry volume of the structure is relevant, but also other dimensions such as: the cross-sectional area of the core in the crotch region; the compressibility of the article in the crotch region and the resulting thickness of the article after bending; the size of "the impact area of the article"; the distance of the elastic members (legs) of the article. Therefore, the core structures described here can be called thin, but wide. Additionally, an "Absorbency Efficiency Index" is described, relating a quantity of fluid, which must be collected by the crotch region, to the volume of the dry core. The objective of this parameter is to allow the design towards the characteristics of high absorbency, capacity, in the crotch region. Therefore, it is still a key objective to also absorb large amounts of urine in the crotch area, which, in any way, inevitably reduces comfort after loading significantly. This issue becomes even more pronounced with the additional improvement of the performance of the absorbent articles producing absorbent articles that provide better performance in the handling of fluids, and consequently an increase in the overall use time and amount of fluid contained in such articles. before being removed. In US-A 4,994,037 (Bernardin) absorbent articles are described, having a "reverse capacity profile". Where, the last storage capacity is placed separately from the crotch region. However, the disclosed designs for the absorbent articles do not consider the adjustment requirements to fit well between the user's legs, nor the fluid handling requirements such as achieving proper skin dryness and fluid acquisition. While these designs arrange capacity away from the loading point, they were not related to how to achieve fluid transport to these storage regions. Because it is an object of the present invention to provide absorbent articles that have an improved fit also when they are loaded, along with good fluid handling performance, especially that they have good acquisition performance. It is further an object of the present invention to achieve this by selectively placing the final storage capacity away from the crotch region. It is a further object of the present invention to provide this feature without detrimentally affecting the fit when dry by providing low volume designs of the article in the crotch region. Furthermore, it is an object of the invention to achieve this by using distribution materials that have high wick-type flow properties. Additionally it is an object of the present invention to achieve this by using superabsorbent polymers. It is further an object of the invention to achieve this by using porous absorbent materials, such as those made by the polymerization of HIPE.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is schematically showing a baby diaper as an example of an absorbent article. Figure 2 is schematically showing a diaper that notches the baby as an example of an absorbent article. Figure 3 is showing the test carried out for the Vertical Wick Effect Test. Figure 4 is showing the test carried out for the Proof of Acquisition. Figure 5 is showing the test carried out by the Post-Acquisition Collagen Rewet Method.

Detailed description.

Absorbent articles - general. As used herein, the term "absorbent articles" refers to devices that absorb and contain exudates from the body, and more specifically, refers to devices that are positioned against or in proximity to the user's body to contain and absorb the variety of Exudates discharged from the body, mainly urine. The term "disposable" herein is used to describe absorbent articles that are not intended to be laundered or otherwise restored or rejected as an absorbent article (for example, they are proposed to be disposed of after use and, preferably, to be recycled, formed in compost or otherwise disposed of in some way compatible with the environment).

An absorbent article generally comprises: an absorbent core or central structure (which may consist of substructures); a top sheet permeable to the fluid; a back sheet impervious to the fluid; optionally additional features such as closing or elasticizing elements. Figure 1 is a plan view of an embodiment of an absorbent article that is a diaper. The friend! 20 is shown in Figure 1 in its uncontracted state, level (eg with contraction of the elastic pulled out induced except the side panels wherein the elastic is maintained in its relaxed condition) with portions of structure being cut away to show more clearly the construction of the diaper 20 and with the portion of the diaper 20 facing from the wearer, the outer surface 52, facing the viewer. As shown in Figure 1, the diaper 20 comprises a containment assembly 22 which preferably comprises a liquid-permeable top sheet 24, a liquid-impermeable back sheet 26 bonded to the top sheet 24, and an absorbent core 28 positioned between the sheet. top sheet 24 and back sheet 26; elasticized side panels 30; folds of elasticized legs 32; a characteristic of elastic waist 34; and a closure system comprising a double tension fastening system generally designated multiple 36. The dual tension fastening system 36 preferably comprises a primary fastening system 38 and a waist closure system 40. The fastening system primary 38 preferably comprises a pair of securing members 42 and a landing member 44. The waist closure system 40 is shown in Figure 1 to preferably comprise a pair of first fastening components 46 and a second fastening component 48. the diaper 20 also preferably comprises a positioning patch 50 located subjacent of each first attachment component 46. the diaper 20 is shown in Fig having an outer surface 52 (facing the viewer in figure 1), an inner surface 54 opposed to the outer surface 52, a first waist region 56, a second waist region 58 opposite the first region ng waist 56, and a periphery 60 which is defined by the outer edges of the diaper 20 in which are designated the longitudinal edges 62 and are designated the end edges 64. The inner surface 54 of the diaper 20 comprises that portion of the diaper 20 it is positioned adjacent the user's body during use (for example the inner surface 54 is generally formed by at least a portion of the topsheet 24 and other components attached to the topsheet 24). The outer surface 52 comprises such a portion of the diaper 20 that is positioned away from the wearer's body (for example, the outer surface 52 is generally formed by at least a portion of the backsheet 26 and other components attached to the backsheet 26). The first waist region 56 and the second waist region 58 extend, respectively, from the end edges 64 of the periphery 60 to the centerline 66 of the diaper 20. Each of the waist regions comprises a central region 68 and a pair of side panels typically comprising the outer side portions of the lines of waist. The side panels placed in the first waist region 56 are designated 70 while the side panels in the second waist region 58 are designated 72. While it is not necessary for the pairs of side panels or each side panel to be identical, they are preferably Specular images one of the other. The side panels 72 placed in the second waist region 58 can be elastically extensible in the lateral direction (eg elasticized side panels 30). (The lateral direction (x or width direction) is defined as the direction parallel to the lateral centerline 66 of the diaper 20; the longitudinal direction (direction y or length) being defined as the direction parallel to the longitudinal center line 67; and the axial direction (z direction or thickness) being defined as the direction extending through the thickness of the diaper 20). Figure 1 shows a diaper specific 20 in which the topsheet 24 and the backsheet 26 extend beyond the edges of the absorbent core 28 to thereby form the periphery 60 of the diaper 20. The periphery 60 defines the outer perimeter or, in other words, the edges of the diaper 20. The periphery 60 comprises the longitudinal edges 62 and the end edges 64. The containment assembly 22 of the diaper 20 is shown in Figure 1 comprising the main body (chassis) of the diaper 20. The containment assembly 22 comprises at least one absorbent core 28 and preferably an outer cover layer comprising the topsheet 24 and the backsheet 26. When the absorbent article comprises a separate fastener and a liner, the containment assembly 22 generally comprises the fastener and the liner (e.g., the containment assembly 22 comprises one or more layers of material to define the fastener while the liner comp renders an absorbent compound such as a topsheet, a backsheet and an absorbent core). For unitary absorbent articles, the containment assembly 22 comprises the main structure of the diaper with other features added to form the structure of the composite diaper. Therefore, the containment assembly 22 for the diaper 20 generally comprises the topsheet 24, the backsheet 26 and the absorbent core 28. While each fold of the elasticized leg 32 may be configured in a manner that is similar to any of The leg bands, side flaps, barrier folds, or elastic folds described above, it is preferable that each fold of the elasticized leg 32 comprises at least one internal barrier fold 84 comprising a barrier flap 85 and an elastic limb of the leg. spacing 86 as described in U.S. Patent No. 4,909,803. In a preferred embodiment, the elasticized leg fold 32 further comprises an elastic packing fold 104 with one or more elastic filaments 105, positioned outside of the barrier fold 84 described in the above-referenced US Patent No. 4,695,278. The diaper 20 can additionally comprise an elastic waist feature 34 that provides improved fit and containment. The elastic waist feature 34 at least extends longitudinally outwardly from at least one of the waist edges 83 of the absorbent core 28 in at least the central region 68 and generally forms at least a portion of the end edge 64 of the diaper 20 Therefore, the elastic waist feature 34 comprises such a portion of the diaper that at least extends from the waist edge 83 of the absorbent core 28 to the end edge 64 of the diaper 20 which is intended to be placed adjacent to the wearer's waist. Disposable diapers are generally constructed in order to have two elastic waist features, one placed in the first waist region and another placed in the second waist region. While a disposable diaper of the present invention may be constructed with a single elastic waist feature surrounding the wearer or having a cushion article at the waist only with back elastics the discussion relates the elastic waist feature will focus on the diapers that have a pair of elastic waist features, at least one, and preferably both, being constructed according to the present invention. Additionally while the elastic waist feature or any of its constituent elements may comprise a separate element attached to the containment assembly 22 of the diaper 20, the elastic waist feature 34 will be described with respect to a preferred embodiment in which the elastic waist feature 34 is constructed as an extension of other diaper elements such as the backsheet 26 or the top sheet 24, preferably both, the backsheet 26 and top sheet 24. The elasticized waistband 35 of the elastic waist feature 34 may comprise a portion of the topsheet 24, a portion of the backsheet 26 that has preferably been mechanically stretched and a material of two. sheets comprising an elastomeric member 76 positioned between the topsheet 24 and the backsheet 26 and the resilient member 77 positioned between the backsheet 26 and the elastomeric member 76. This, as well as other components of the diaper are given in more detail in WO 93/16669 which is incorporated herein by reference. Figure 2 shows a further example of an absorbent article for which the present invention can be applied, ie a disposable notch diaper. The disposable notch diaper 20 comprises a chassis 21, side seams 23, and an absorbent assembly 22. The chassis 21 will have at least a front portion 56, a back portion 58, a crotch portion 57, longitudinal side regions 88, and fins of ear 72 and will comprise an elastic ear fin member 90 operatively associated with each ear flap 72 to form a laminated ear flap that will be elastically activated by a mechanical stretching process which will be described in greater detail here below. The absorbent assembly 22 is secured to the chassis 21. The outer layer 26 is that portion of the chassis 21 that will form the exterior of the disposable diapers 20, for example from the front of the wearer. The outer layer 26 is docile, soft feeling and non-irritating to the wearer's skin. The inner layer 24 is that portion of the chassis 21 that will form the interior of the chassis 21, and will contact at least the user's waist and legs. The inner layer is also docile, soft feeling and non-irritating to the user's skin. The inner layer 24 is preferably placed adjacent to the outer layer 26 and is preferably attached to the previous one by means of fixation (not shown) such as those well known in the art. For example, the inner layer 24 can be secured to the outer layer 26 by a uniform continuous layer of adhesive, a layer of patterned adhesive, or an array of separate lines, spirals or spots of adhesive. According to one embodiment of the invention, the inner layer 24 and the outer layer 26 are indirectly joined together by attaching them directly to the elastic ear flap members 90, elastic waist band members 76, and elastic filaments 105 and are directly joined together in the areas extending beyond the elastic ear flap member 90, elastic waistband members 76 and elastic filaments 45. In a preferred embodiment, at least a portion of the inner frame and outer layers 24, 26 will be fastened to mechanical stretch in order to provide a "class zero" laminate stretch that forms the elastified ear flaps 30. Therefore, the inner and outer layers 24, 26 are preferably elongable, more preferably stretchable, but not necessarily elastomeric, in such a way that the inner and outer layers 24, 26 will be, over mechanical stretching, at least to a permanently elongated degree t to which they will not return completely to their original, undistorted configuration. In preferred embodiments, the inner and outer layers 24, 26 may be subject to mechanical stretching without undue tearing or tearing. Accordingly, it is preferred that the inner and outer layers 24, 26 have a low resistance produced in the direction transverse to the machine (lateral direction). The chassis 21 of disposable diapers notch 20 preferably further comprises folds of elasticized legs 32 to provide improved containment of liquids and other exudates from the body. Each elasticized leg fold 32 may comprise several different embodiments to reduce runoff of the body exudates in the leg regions. As each fold of the elasticized leg 32 can be configured in such a way as to be similar to any of the leg bands, side flaps, barrier folds, or elastic folds described above, it is preferred that each elastic leg fold 32 comprises at least one side flap 104 and one or more elastic strands 105. The chassis 21 of the disposable diapers 20 further comprises preferably an elasticized waistband 34 positioned adjacent the edge 64 of the disposable waist diaper 20 in at least the rear portion 58, and more preferably has an elasticized waistband 34 positioned in both, the front portion 56 and the rear front portion 58. The waistband of the disposable diaper 20 is such a portion that it is proposed to be placed adjacent to the wearer's waist. The elasticated waistband 34 provides a member that maintains a defined area coverage, contacts the wearer's waist, and is elastically extensible in at least the lateral direction such that it dynamically adjusts against the wearer's waist and to dynamically accommodate at the user's waist to provide improved fit. Accordingly, the waistband generally is such a portion of the disposable notch diapers 20 extending from the end edge 64 of the disposable notch diapers 20 to at least the waist edge 83 of the absorbent core 28. While the waistband 34 can comprising an element attached to the chassis 21 of the disposable notch diapers 20, the waist band preferably is an extension of other elements of the disposable notch diapers 20 such as the inner layer 24, the outer layer 26 or any combination thereof elements and an elastomeric material attached to the above. Alternatively, the topsheet and the backsheet of the absorbent assembly 22 can extend beyond the absorbent core edges 28 and have an elastomeric material bonded thereto to form an elastic waistband. Elastic trainers are always constructed to have elastic waistbands; one placed on the front portion 56 and one positioned on the rear portion 58. The disposable napkin diapers 20 have an elastic waistband 34 disposed at least in the central region 68 of the back portion 58. Preferably another elastic waistband is disposed in the back portion. front 56. Preferably both elasticised waistbands 34 are disposed between the elastified ear flaps 30. The elasticized waistband 34 may be constructed in a number of different configurations. According to Figures 2 and 3, the elasticized waistband 34 comprises an elastic waistband member 76 interposed between the inner layer 24 and the outer layer 26 and is operatively associated with one or both of the inner and outer layers 24, 26 together with the front portion 56 and the back portion 58 of the disposable notch diaper 20. In a preferred embodiment, the chassis 21 comprises elasticized ear flaps 30 in the front portion 56 and the back portion 58. The elasticized ear flaps 30 are Unitary elements of the chassis, for example, are not manipulative elements secured separately to the chassis, but instead are formed from and are extensions of the chassis materials. The elasticized ear flaps 30 provide an elastically stretchable article that provides a contour fit and more comfortable initially comfortable fitting of the disposable undergarment to the wearer and holding this fit throughout the last time of use when the garment The disposable interior has been loaded with the exudates because the elasticized ear flaps allow the edges of the underwear to expand or contract. Each ear flap 72 comprises such a portion of the chassis 21 extending laterally outwardly from and along the central region 68 of the chassis 21 to the longitudinal side region 88 of the chassis 21. The ear flap 72 generally extends longitudinally. from the end edge 64 of the chassis 21 to the longitudinal edge portions 62 of the chassis 21 that forms the opening of the leg (this segment of the longitudinal edge 62 being designated as the leg edge 106).

In a preferred embodiment of the present invention, each ear flap is formed by the portions of the inner layer 24 and the outer layer 26 that extends beyond the central region 38 of the chassis 21. In one embodiment of the present invention , the elastic ear flap members 90 are operatively associated with the chassis 21 in the ear flaps 72, preferably between the inner layer 24 and the outer layer 26, such that the elastic flap members 90 allow the the elasticized ear flaps 30 can be extendable elastically in the lateral direction (extendable laterally elastically). As used herein, the term "elastically extensible" means a segment or portion of the chassis that will elongate in at least one direction (preferably the lateral direction for the ear flaps and the waistband) when the tension forces (typically tension forces) laterals for the ear flaps and waistband) are applied, and will return close to their size and configuration when the tension forces are removed. Generally, the elastomeric materials useful in the present invention will contractually return to at least about 75% of the original configuration within about 5 seconds or less of the stretch and immediate release of the former (e.g., "energetic" elastic) .

Absorbent core / central structure The absorbent core 28 must be generally compressible, comfortable, non-irritating to the wearer's skin, and capable of absorbing and retaining liquids such as urine and certain other exudates from the body. As shown in Figure 1, the absorbent core 28 has an undergarment surface (the "lower" or "lower" portion), a body surface, side edges and waist edges. The absorbent core should comprise a wide variety of liquid handling or liquid absorbent materials commonly used in disposable diapers and other absorbent articles such as - but not limited to - pulp of crushed wood which is generally referred to as a filter. air; meltblown extrusion polymers including coform; chemically hardened, modified or crosslinked cellulosic fibers; tissue that includes tissue wrapping or tissue laminates. Examples of absorbent structures are described in U.S. Patent No. 4,610,678 entitled "High Density Absorbent Structures" issued to Weisman et al. On September 9, 1986, U.S. Patent No. 4,673,402 entitled "Absorbent Articles With Double Layer Cores "issued to Weisman et al. On June 16, 1987, US Patent No. 4,888,231 entitled" Absorbent Core Having a Fine Layer of Dust "issued to Angstadt on December 19, 1989; EP-A-0 640 330 to Bewick-Sonntag et al .; US 5 180 622 (Berg et al.); US 5 102 597 (Roe et al.); US 5 387 207 (LaVon). Such structures must be adopted to be compatible with the requirements outlined below to be used as the absorbent core 28. The absorbent core 28 can be a unitary central structure, or it can be a combination of several absorbent structures, which in turn can consist of one or more substructures. Each of the structures or substructures can have an extension essentially of two dimensions (for example a layer) or a figure of three dimensions.

Materials to be used in absorbent cores The absorbent core for the present invention may comprise fibrous materials to form fibrous webs or fibrous matrices.

Fibers useful in the present invention include those that are naturally occurring fibers (modified or unmodified), such as synthetically made fibers. Examples of suitable fibers that occur naturally unmodified / modified include cotton, esparto grass, bagasse, kemp, flax, silk, wool, wood pulp, chemically modified wood pulp, jute, rayon, ethyl cellulose, and cellulose acetate. Convenient synthetic fibers may be polyvinyl chloride, polyvinyl fluoride, polytetrafluoroethylene, polyvinyl diene chloride, polyacrylics such as ORLON®, polyvinyl acetate, polyethyl vinyl acetate, soluble or insoluble polyvinyl alcohol, poliefins such as polyethylene (e.g. PULPEX®) and polypropylene, polyamides such as nylon, polyesters such as DACRON® OR KODEL®, polyurethanes, polyesters, and the like. The fibers used can comprise only naturally occurring fibers, only synthetic fibers or any compatible combination of synthetic fibers or that occur naturally. The fibers used in the present invention may be hydrophilic, or may be a combination of both hydrophilic and hydrophobic fibers. "* For many absorbent cores or core structures according to the present invention, the use of hydrophilic fibers is preferred The hydrophilic fibers suitable 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 by surfactants or treated by silica derived from, for example, polyolefins such as polyethylene or polypropylene, polyacrylics, polyamides, polystyrenes, polyurethanes and the like Conventional wood pulp fibers can be obtained from well-known chemical processes such as Kraft and sulfite processes, it is especially preferred to derive these fibers of wood pulp from forests ti ernos from the south due to its high quality absorbency characteristics. These wood pulp fibers can also be obtained from mechanical processes, such as earth wood, mechanical refinery, thermomechanical, chemomechanical, and chemotherapeutic-mechanical pulp processes. Secondary or recycled wood pulp fibers, as well as pulp fibers from bleached or unbleached wood can be used. Chemically hardened fibers are a desirable source of hydrophilic fibers for use in the present invention, especially for absorbent regions that require both good fluid acquisition and distribution properties. As used herein, the term "chemically hardened cellulose fibers" means cellulosic fibers that have been hardened by chemical means to increase the hardness of the fibers under both dry and aqueous conditions. Such means may include the addition of a thermal curing agent which, for example, covers and / or impregnates the fibers. Such means may also include hardening the fibers alternating the chemical structure, for example by crosslinking the polymer chains. Polymeric curing agents that coat or impregnate cellulose fibers include: cationic modified starches having nitrogen-containing groups (e.g., amino groups) such as those available from National Serch and Chemical Corp., Bridgewater, NJ, USA, latexes, moisture resistant resins such as polyamideepichlorohydrin resin (for example Kymene® 557H, Hercules, Inc. Wilmington, Delawaare, 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 distributed by American Cyanamide Co., Stanford, CT, USA, under the trademark Parez® 631 NC; resins of formaldehyde of urea and formaldehyde of melamine, and resins of polyethyleneimine. A general dissertation on the resins resistant to the humidity used in the technique of the paper, and generally applicable here, can find in the monographic series TAPPI No. 24. "Resistance to the humidity in Paper and Cardboard", Technical Association of the Industry of Paper and Pulp (New York, 1965). These fibers can also harden by chemical reaction. For example, crosslinking agents can be applied to the fibers, which subsequent to the application, are chemically caused by crosslinked bonds between the fibers. These crosslinked bonds can increase the hardness of the fibers. While the use of crosslinked bonds between the fibers is preferred to chemically harden the fiber, it is not intended to exclude other types of reaction for chemical hardening of the fibers. The fibers hardened by crosslinked bonds in an individualized manner (eg, hardened individualized fibers, as well as the process for their preparation) are disclosed, for example, in U.S. Patent No. 3,224,926 (Bernardin) issued December 21, 1965, U.S. Patent No. 3,440,135 ( Chung), issued on 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 the currently preferred hardened fibers, the chemical process includes crosslinking between the fibers with crosslinking agents while such fibers are in a condition relatively dehydrated, defibrated (for example, individualized), twisted, curled. Chemical hardening agents are typically crosslinked agents which include especially C2-C9 polycarboxylic acids such as citric acid.

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 at locations in which 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. Such additional hardened fibers will have an average dry fiber twist count of at least about 2J, preferably about 4.5 twists, knots per millimeter. Additionally, 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 fiber that is routed can be quantified by referring to a fiber curl factor. The curl factor of the fiber, 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 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 the Patent of the United States No. 4,898,642. Preferably, the hardened fibers will have a curl factor of at least about 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 structures 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.

Additionally or alternatively the thermoplastic or synthetic fibers can be comprised in the absorbent structures, being made of any thermoplastic polymer that can be melted at temperatures that extensively damage the fibers. Preferably, the melting point of this thermoplastic material will be less than about 190 ° C and preferably between about 75 ° and about 175 ° C. In any event, the melting point of this thermoplastic material should not be less than the temperature at which thermally bonded absorbent structures, when used in absorbent articles, are likely to be stored. The melting point of the thermoplastic material is typically not less than about 50 ° C. The thermoplastic materials, and in particular the thermoplastic fibers may be made from a variety of thermoplastic polymers, including polyolefins such as polyethylene, (eg, PULPEX®) and polypropylene, polyesters, copolyesters, polyvinyl acetate, polyamides, copolyamides, polystyrenes , polyurethanes, and copolymers of any of the foregoing such as vinyl chloride / vinyl acetate, and the like. Suitable thermoplastic materials include hydrophobic fibers that have been made hydrophilic, such as thermoplastic fibers treated by surfactants or treated with silica derived from, for example, polyolefins such as polyethylene or polypropylene, polyacrylics, polyamides, polystyrenes, polyurethanes, and the like. The surface of the hydrophobic thermoplastic fiber can be converted into hydrophilic by treatment with a surfactant, such as a nonionic or anionic surfactant, for example, by spraying the fiber with a surfactant, bathing the fiber within a surfactant or including the surfactant as part of the molten polymer in the production of the thermoplastic fiber. Upon melting and resolidification, the surfactant will tend to remain on the surface of the thermoplastic fiber. Surfactants may also be used including nonionic surfactants such as Brij® 76 manufactured by ICI Americas, Ine, of Wilmington, Delawer, and various surfactants sold under the tradename Pegosperse® by Glyco Chemical Inc. of Greenwich, Connecticut. . In addition to the nonionic surfactants, anionic surfactants can also be used. These surfactants can be applied to the thermoplastic fibers at the levels of, for example, from about 0.2 to about 1 gram square centimeter of thermoplastic fiber. Convenient thermoplastic fibers may be made of a single polymer, (monocomponent fibers), or they may be made of more than one polymer (for example bicomponent fibers). For example, "bicomponent fibers" can refer to thermoplastic fibers comprising a fiber core made of a polymer that is enclosed within a thermoplastic shell made of a different polymer. The polymer comprising the shell always melts at a different temperature, typically lower, than that of the polymer comprising the core. As a result, these bicomponent fibers provide thermal bonding due to fusion of the shell polymer, while retaining the desirable strength characteristics of the core polymer. Suitable bicomponent fibers for the present invention may include shell / core fibers having the following polymer combinations: polyethylene / polypropylene, polyethyl vinyl / polypropylene acetate, polyethylene / polyester, polypropylene / polyester, copolyester / polyester, and the like. Particularly, the bicomponent thermoplastic fibers suitable for use herein are those having a polypropylene or polyester core, and a lower melting shell of copolyester, polyethyl vinyl acetate or polyethylene (eg, DANACLON® fibers)., CELBOND® or CHISSO®). These bicomponent fibers may be concentric or eccentric. As used herein, the terms "concentric" and "eccentric" refer to whether the shell has a thickness that is flat, or not flat, across the cross-sectional area of the bicomponent fiber. The bicomponent eccentric fibers may be desirable in providing more compressive strength at lower fiber thicknesses. Suitable bicomponent fibers for use therein may be either uncurled (eg curled). The bicomponent fibers may be crimped by typical textile means such as, for example, a Stuffer child method or the method of curling garments to achieve a predominantly two-dimensional or "flat" curl. • In the case of thermoplastic fibers, their length may vary depending on the particular melting point and other properties desired for these fibers. Typically, these thermoplastic fibers have a length of from about 0.3 to about 7.5 cm in length, preferably from about 0.4 to about 3.0 cm in length. The properties, including the melting point, of these thermoplastic fibers can also be adjusted by varying the diameter (gauge) of the fibers. The diameter of these thermoplastic fibers is typically defined in terms of either denier (grams per 900 meters) or decitex (grams per 10,000 meters decitex.) Depending on the specific arrangement within the structure, suitable thermoplastic fibers may have a decitex in the interval from well below 1 decitex, such as 0.4 decitex to about 20 dtex. Said fibrous materials can be used in an individualized way when the absorbent articles are being produced, and a fibrous structure placed by air is formed on the line. Said fibers can also be used as a preformed fibrous web or tissue. Then, the structures are supplied to the production of the article essentially in very long or extreme form (for example in a roll, reel) and then it will be cut into the appropriate size. This can be done in each of such materials individually before they are combined with other materials to form the absorbent core, or when the core itself is cut and said materials are coextensive with the core.

There is a wide variety of making such plies or tissues, and such processes are well known in the art. With respect to the fibers used to produce such wefts, in principle there is no close limitation - thought that certain processes of union and formation of specific wefts should not be completely compatible with certain types of materials or fibers. When individualized fibers are observed as starting materials to make a weft, they can be deposited in a fluid medium - if plague is gaseous (air), such structures are generally referred to as "air-laid" if it is liquid. such structures are generally referred to as "wet laid". "Wet-laid" is widely used to produce paper tissues with a wide range of properties. This term is most commonly used with cellulosic materials, however synthetic materials may also be included. "Dry-laid" is widely used for nonwoven webs and the carding process can always be used to form such webs. Also the commonly known "tissues placed by air" falls into this category. A molten polymer can be extruded into fibers which can then directly form a web (e.g., bypass the process of making individual fibers which are then formed into a web in a separate step of the process). The resulting structures are commonly referred to as non-wovens of the melt-blow-extrusion type or - if the fibers are significantly more extensible - spunbonded fabrics. On the other hand, frames can also be formed by combining one or more of the training technologies.

In order to give certain properties of integrity and resistance to the structures of the frame, they are generally joined together. The most widely used technologies are (a) chemical bonding or (b) thermo bonding, melting a part of such a frame. For the later, the fibers can be compressed, resulting in different points of union, which, for example for the non-woven materials, can cover a significant portion of the total area, are not unes 20% values. Or it can be applied - particularly useful in materials in which low densities are desired - the "through-air" bond, where the polymer arts, for example the shell material of a BiCo fiber, are melted by means of heated air that passes through the frame (always placed by air). After the frames are formed and joined, they can be further processed to modify the specific properties. This can be - as one of several possible examples - additional surfactant to convert the more hydrophilic hydrophobic fibers, or vice versa. Also, post-formation mechanical treatment, as disclosed in European application 96108427.4, can be used to impart particularly useful properties for such materials. Additionally or alternatively to the fibrous webs, the absorbent cores may comprise other waste materials, such as foams. Preferred foams are open cell absorbent polymeric foam materials being derived by polymerizing a High Internal Phase Water Emulsion (hereinafter referred to as EAFI). Such polymeric foams to provide the required storage properties, as well as the distribution properties that are required. The foams derived from the EAFI that provide both the storage and distribution properties required for their use are described herein in the copending United States Patent Application Serial Number 08 / 563,866 (DesMarais et al.), Filed on November 25, 1995 (hereinafter referred to as "application 866"), the disclosure of which is incorporated herein by reference; U.S. Patent Application Serial Number 08 / 542,497, filed October 13, 1995 (Dyer et al.); 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 incorporated herein by reference. The polymeric foams useful in the present invention are those of relatively open cell. This means that the individual cells of the foam are in unobstructed, complete communication with the adjoining cells. The cells in such foam structures of substantially open cells have intracellular openings or "windows" that are long enough to allow easy transfer from one cell to the other within the structure of the sponge structure. These relatively open cell sponge structures will generally have a cross-linked character with the individual cells being defined by a plurality of mutually connected three-dimensional branched frames. The filaments of the polymeric material that make 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 microphotographs 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 the foam structure that are at least 1 micrometer 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 the aqueous fluids in the successive specified amounts. The internal surfaces of the foam structures are converted into hydrophilic by hydrophilizing residual surfactants deposited in the polymer structure after polymerization, or by selected processes of foam treatment after polymerization. Polymeric foams can be prepared in the collapsed form (eg unexpanded), polymeric foams which, upon contact with the aqueous fluids, expand and absorb such fluids. See, for example, U.S. Patent Application Serial Number 08 / 563,8766 and U.S. Patent No. 5,387,207. These collapsed polymeric foams are usually obtained by rapidly transporting the phase of! water from EAF foam! polymerized through compressible forces and / or thermal drying, and / or vacuum draining. After compression and / or thermal drying / vacuum draining, the polymeric foam is in a collapsed or unexpanded state. Non-collapsible sponges, such as those described in co-pending United States Patent Application Serial Number 08 / 542,497 and United States Patent No. 5,260,345 are also useful as distribution material.

Super absorbent polymers or hydro Optionally, and always preferable, the absorbent structures according to the present invention may comprise superabsorbent polymers or hydrogels. The hydrogel-forming absorbent polymers useful in the present invention include a variety of substantially water-insoluble but water-swellable polymers capable of absorbing large quantities of liquids. Such polymeric materials are also commonly referred to as "hydrocolloid" or "superabsorbent" materials. These hydrogel-forming absorbent polymers have a multiplicity of functional groups, anionic, such as sulfonic acid, and more typically carboxyl groups. Examples of suitable polymers for use herein include those which are prepared from the acid-containing, unsaturated, polymerizable monomers. Some non-acidic monomers may also be included there, usually in minor amounts, in the preparation of hydrogel-forming absorbent polymers. Some non-acidic monomers may include, for example, the water-soluble or water-dispersible esters of the acid-containing monomers, as well as the monomers which do not contain sulfonic or carboxylic acid groups at all. Examples of such well-known materials are described, for example, in U.S. Patent No. 4,076,663 (Masuda et al.), Issued February 18, 1978, and U.S. Patent No. 4,062,817 (Westerman), issued at December 13, 1977. Suitable hydrogel-forming absorbent polymers suitable for the present invention contain carboxyl groups. These polymers include acrylonitrile-hydrolyzed starch copolymers, acrylonitrile-partially neutralized starch copolymer copolymers, acrylic acid-starch insert copolymers, partially neutralized acrylic acid-starch copolymer copolymers, acrylic ester-vinyl acetate copolymers saponified, hydrolyzed acrylamide or acrylonitrile copolymers, softly crosslinked network polymers of any of the foregoing copolymers, partially neutralized polyacrylic acid, and cross-linked network copolymers 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 polymeric materials are disclosed in U.S. Patent 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. Pat. of the United States No. 4,734,478. The most preferred polymer materials for use in the manufacture of hydrogel-forming particles are softly cross-linked network polymers of partially neutralized polyacrylic acids and starches derived from the foregoing. More preferably, the hydrogel forming particles comprise from about 50 to about 95%, preferably about 75%, of polyacrylic acid, of gently crosslinked, neutralized network (e.g., poly (acrylic acid-sodium acrylate)). As described above, the hydrogel-forming absorbent polymers are preferably smoothly cross-linked network. Reticularizing the network serves to convert the substantially insoluble polymer into water and, in parts, determine the absorbent capacity and the characteristics of the extractable polymer content of the precursor particles and the resulting macrostructures. The processes for network cross-linking, polymers and typical network crosslinking agents are described in greater detail in the above-referenced U.S. Patent No. 4,076,663, and in DE-A-4020780 (Dahmen). The superabsorbent materials can be used in the form of particles or fibrous form and other elements can also be combined to form preformed structures. While the individual elements have been separately disclosed, and their absorbent structures can be made by combining one or more of those elements. Without pretending a limiting effect, the following describes suitable combinations: Particular Superabsorbent Polymer (PSP) mixed with cellulose fibers or others. By basic principle it is well stabilized and known, however in the attempt to reduce the thinness of the articles, higher and higher proportions of PSP weights to fibers have recently been employed. Within this matter, combinations of the PSP with binders such as hot melt adhesives, (such as those disclosed in EP-A-0,695,541) or with meltable polymeric material (such as PE particles) can be a convenient tool for immobilize the PSP; PSP that form a structure by the cross-links between the particles; Fibrous PSP being mixed with other fibers, or forming a fibrous PSP screen; Foam structure comprising differences in pore size, etc.

Improved absorbent articles After having described the absorbent articles and the suitable materials, structures, components or subcomponents in general terms, the following will describe the specific characteristics according to the present invention. Therefore, attention is focused on describing the urine discharge management of the respective users, and the resulting urine management requirements for the absorbent structures. It should be noted, however, that the same fluid handling mechanism applied to discharges based primarily on water, such as very low viscosity feces, or menstrual fluids.

Regions of absorbent articles Generally, absorbent sanitary articles are proposed to make dresses at the lower end of the body torso. It is an essential feature of the design of these articles to cover the regions of the body where the discharges occur ("unloading regions"), which extend around the respective body openings. The respective zones of the absorbent article covering the discharge regions are correspondingly referred to as "loading zones". Then, during use, the articles are generally arranged on the user in such a way that they extend (for a standing position of the user) from the crotch between the upper part of the legs, on both front and back of the user. "Generally, such articles have a length dimension that extends their width dimension, so the article is used in such a way that the axis of the length dimension is aligned with the user's highest direction when standing, while The direction of the width of the article is aligned with a line that extends from the user's left to right.Due to the anatomy of the human user, the space between the user's legs generally limits the space available for the article in this region. Good fit, an absorbent article should be designed in such a way that it fits well in the crotch region.If the width of the article is too wide relative to the width of the wearer's crotch, the item may be deformed, which would result in a deteriorated performance and reduced user comfort The point, where the item has its smallest width for the best fit between the user's legs onces coincides with the point of the user, where the distance between the legs is the narrowest, and is - by the subject matter of the present invention - referred to as the "crotch point".

If the crotch point of an article is not obvious from its shape, it can be determined by placing the article in a user of the proposed user group (for example a child who is just beginning to walk) preferably in a standing position, and then placing an extendable filament around the legs in a figure-eight configuration. The point in the article corresponding to the point of intersections of the filament is considered to be the point of the crotch of the article and consequently also of the absorbent core being fixed within this article. While this crotch point of the article is always in the middle of the article (in the longitudinal direction) this is not necessarily the case. It can be very good that the part of the article that is proposed for dressing on the front is smaller than the back (or rear) - whether in its length or width dimension or both or surface area. Also the crotch point need not be placed in the middle of the absorbent core, in particular when the absorbent core is not positioned longitudinally centered within the article. This region of the crotch is the area that surrounds the crotch point, in order to cover the openings of the respective body, discharge regions respectively. Unless otherwise mentioned, this region extends over a length of 50% of the total length of the core (which in turn is defined as the distance between the front and rear waist edges of the core, which should be approximated by straight lines perpendicular to the longitudinal center line). If the crotch point is placed in the middle of the article, then the crotch region begins (when it continues from the front edge of the core) at 25% of the total length and extends above 75% of the total length of the crotch. core. Or, the front and rear quarters of the length of the absorbent core that should not touch the crotch region, the rest does.

The length of the crotch region being 50% of the total length of the absorbent core has been derived for baby diapers, where it has been confirmed that this is a convenient means to describe the phenomenon of fluid handling. If the present invention is applied in articles that have drastically different dimensions, it will be necessary to reduce that 50% (as in the case for the articles of Severe Incontinence) or to increase this proportion (as in the case for the articles of Light Incontinence or Ultra Lightweight). More generally, this crotch region of the article should not extend much beyond the user's download region. If the crotch region is placed out of place from the midpoint of the article, the crotch region still covers 50% of the total length of the article (in the longitudinal direction), however not properly distributed between the front and back. the back, but proportionally adjusted to this one out of place. As an example for an article having a total core length of 500 mm, and having a crotch point that is positioned centered, the crotch region will extend from 125 mm. from the front edge above 375 mm. from the front edge or, if the crotch point rests 50 mm. out from the front edge of the core, (for example being 200 mm from the front edge of the core), the crotch region extends from 100 mm. at 350 mm. Generally speaking, for an article having a total length of the core of Lc, a crotch point being placed at a distance Lep from the front edge of the core, and a length of the crotch region of Lcz, the front edge of said core. crotch area will be placed at a distance Lfecz = Lep * (1 - Lcz / Lc). For example, the absorbent article can be a baby diaper, for use by children who are just beginning to walk (for example, the baby's weight of around 12 to 18 kg.) So the size of the item in the trade is generally referred to as MAXI size. The article must then be able to receive and retain both fecal materials and urine, however, in the context of the present invention, the crotch region must be capable of receiving primarily urine loads. The size and total area of the crotch region is - of course - also dependent on the respective width of the absorbent core, for example if the cores are narrower in the crotch region than the outside of the crotch region, the crotch region has a smaller area (surface) than the surplus area of the absorbent core. While it can be contemplated, the joints between the crotch region and the rest of the article can also be curvilinear, are approximated within the present description to be straight lines, perpendicular to the longitudinal axis of the article. The "crotch region" is additionally limited by the width of the core in its respective region, and the "area of the crotch region" by the surface being defined by the length of the crotch region and the respective width. As a complementary element to the crotch region, the absorbent core also comprises at least one but mainly two waist regions, which extend towards the front and / or rear of the absorbent core outside the crotch region.

Design Capacity and Ultimate Storage Capacity In order to be able to compare absorbent articles varying extreme conditions of use, or items with different sizes, the "design capacity" has been found to be a convenient measure.

For example babies that are representing a typical user group, but even within this group the amount of urine load, frequency of load, composition of urine will vary widely from the smallest babies (newborn babies) to children starting to walk, on one side, or also for example between several individual children who start to walk. Another group of users may be older children, who still suffer from some form of incontinence. Also, incontinent adults can use such items, again with a wide range of load conditions, generally referred to as light incontinence ranging up to severe incontinence. While the person skilled in the art will easily be able to transfer the teachings to other sizes for later discussions, attention will be placed on babies the size of children who are just beginning to walk. For such users urine loads above 75 ml. by evacuation, with an average of four evacuations per period of use resulting in a fecal load of 300 ml., and evacuation rates of 15 ml / sec have been found to be sufficiently representative. Therefore, such items being able to get ahead with such requirements must have the ability to collect such amounts of urine, which will be referred to for later discussions as "design capacity". These quantities of fluids have to be absorbed by materials that can ultimately store the body fluids, or at least the aqueous parts of them, in such a way that - if there is one - only little fluid deposited on the surface of the article towards the user's skin. . The term "last" refers in one respect to the situation of the absorbent article in long times of use, in the other respect to absorbent materials that reach their "ultimate" capacity when they are balanced with their environment. This may be in such an absorbent article under actual conditions of use after long periods of use, or this may also be in a test procedure for pure materials or composite materials. Since many of the processes under consideration have an asymptotic kinetic behavior, one skilled in the art will readily consider that the "ultimate" capacities are reached when the current capacity has reached a value sufficiently close to the asymptotic endpoint, for example, relative to the precision of the measuring equipment. As an absorbent article may comprise materials that are primarily designed to store fluids lately, and other materials that are designed primarily to satisfy other functions such as fluid acquisition and / or distribution, but may still have some ultimate storage capacity, convenient for Core materials according to the present invention are described without intending to artificially separate such functions. However, the ultimate storage capacity can be determined by total absorbent core, for the above regions, for the absorbent structures, or even substructures, but also for materials as used in any of the permeable ones. As discussed above to vary the dimensions of the article, one skilled in the art will be able to easily adopt the appropriate design capabilities for other proposed user groups.

Profile An important element of the present invention is a specific arrangement of the total absorbent capacity around several regions of the absorbent article, such that the adjustment of the absorbent article in the wearer's body is still comfortable even when the article is loaded up to or in Your Design Capacity This specific arrangement is essentially aimed at providing only very small final storage capacity in the crotch region. The capacity of a specific region can be determined by: the base weights of the absorbent materials under consideration (expressed in grams of material per unit area); - the absorbent capacities of the materials (expressed in ml capacity per grams of material); - the area of said region, by the present discussion defined by the longitudinal dimension of the region and the respective (not necessarily constant) width throughout this region. The first two factors can be combined with the base capacity (expressed in ml per unit area). If any of these parameters is not constant (call width, or base weights or composition), one skilled in the art will be able to easily calculate the averages or heavy factors, such as totalizing (or integrating) the variation parameter and dividing by the respective parameter has been totalized all. Therefore, one way of expressing the requirements of the small Ultima Storage Capacity in the crotch region is by defining that the crotch region has a lower base capacity than the remaining part of the absorbent structure. Then, the base capacity of the crotch region should not be greater than 0.9 times the average base capacity of the remaining parts of the absorbent core, preferably less than OJ times. However, the most preferred design still has a reduced base capacity in the crotch region, still less than 0.3 times the capacity of the remaining parts of the absorbent core. The crotch region may have a uniform base capacity or comprise subregions with varying base capacities. In a preferred specific design, parts of the crotch region essentially have no ultimate storage base capacity, and such portions may cover 50% or more of the area of the crotch region. Another way of describing these requirements for having low absorbent capacity in the crotch region is by observing the longitudinal sectioned regions of the absorbent core, such as by sectioning the absorbent core in a front, middle or back third, or a crotch region that has 50% of the total length of the nucleus and that comparing this with the remaining sections of the nucleus. This ultimate sectional storage capacity of the crotch region must then be less than 49% of the final storage capacity of the total absorbent core. More preferably for a further improved fit when loaded, still less absorbent capacity is preferred in said crotch region, ie less than 41% of the total absorbency capacity, or even more preferred of less than 23%. The distribution profile of the final storage capacity can be determined by calculating the materials in the respective sections, or also measured for example by cutting an article into sections having a dimension of known length and determining the absorbent capacity per section. If, as always in modern absorbent articles, superabsorbent articles are used as a last storage material, a further way to define the requirements for low absorbent capacity in the crotch region is by limiting superabsorbent capacity in analogy with the just discussed total absorbent capacity, for example, having less than 49% of the superabsorbent capacity, preferably less than 41% and more preferably less than 25% in the crotch region.

Therefore, the "reverse profile" of the last absorbent capacity can be achieved by two non-exclusive, different ways: The first begins from a constant "base capacity" throughout the absorbent article, and the profile is reached by giving it a figure to the article in such a way that the crotch region has a smaller area than the remaining regions. Consequently, the longitudinal "longitudinal capacities" will be higher for the regions external to the crotch region. The second begins with the "base capacity" reduced in the "crotch region", which - even for a rectangular-shaped core - would provide less capacity in the crotch region. Of course, combinations of two options can additionally sharpen the profile. In addition to the relocation of the absorbent capacity away from the crotch region, it may be desirable that the fluid storage capacity is not distributed even between the front and back portions. Instead, it may be preferred to adjust the distribution of capacity to the specific requirements of the user's anatomy, and the use-use situation that almost always occurs. For example, for baby diapers proposed for dressing by active children who are just beginning to walk it is desirable to have less capacity in the frontal region than in the posterior region. Also for people with adult incontinence, which may sometimes be bedridden, a distribution of rear asymmetric end storage capacity (such as that described in EP-A-0692322) may be beneficial. In a preferred embodiment for the baby diapers, less than half the final storage capacity, more preferably less than one third of the ultimate storage capacity that is placed externally of the crotch region placed forward, for example in the region of the front portion of the waist, and more than half of the final storage capacity, preferably at least two thirds are placed in the rear part of the article. However, there is an additional requirement involved by the above designs, that is, to provide good acquisition performance. As described above, the loading zone of the absorbent article generally rests in the crotch region. However, the liquid storage capacity is preferably located outside the crotch region. Consequently, the discharged liquid has to be transported from the loading zone to the storage zone, either at sufficiently high fluid transport rates to exceed the fluid release to the article, or in combination with an intermediate fluid handling ability . The balance of the properties of the material in the crotch region must be such that sufficient intermediate storage capacity is provided, but still allowing rapid and preferably complete transport to the material of last storage. If these conditions are met, the article will provide good fluid acquisition performance, which will preferably be maintained for several load cycles. The absorbent core needs to be able to acquire, distribute, and store discharges initially deposited on the topsheet of the absorbent article. Preferably the design of the absorbent core is such that the core acquires the discharges substantially immediately after they have been deposited on the top sheet of the absorbent article, with the intention that the discharges do not accumulate on or escape from the top sheet , because this could result inefficient fluid containment by the absorbent article which can lead to wetting of external garments and discomfort of the wearer. Preferably, the articles have an acquisition speed of more than 3.5 ml / sec in the acquisition test as described herein, preferably more than 4.0 ml / sec, more preferably more than 4.2 ml / sec for the first jet, or 0.5 ml / sec, preferably more than 0.6 ml / sec, more preferably more than OJ ml / sec in the fourth stream. In order to achieve such storage properties of intermediate fluid and fluid transport, capillary transport is a mechanism always used. Such mechanism depends largely on the formed capillaries. However, such transport not only needs to be able to exceed certain heights, but it also needs to have a sufficiently high fluid transport rate. Therefore, suitable materials should not only be able to quickly reach the required vertical heights, as in vertical wicking tests but also transported should transport sufficient quantities of fluid to such heights. It has been found that certain useful materials actually transport wick at a height of 8.3 cm in less than 13 seconds, or heights in wick effect of 12.4 cm in less than 4.5 seconds. But not only the time to reach certain heights is important, but also the flow at 8.3 cm is preferably greater than 0.32 ml / sec / cm2, or preferably more than 0.16 ml / sec / cm2 at a height of 12.4 cm. These requirements as well as the materials suitable for satisfying such requirements have been disclosed in the European Application 96108427.4, additionally the requirements of the performance of acquisition and dryness of the skin and / or rewetting are also disclosed. However, no consideration was made with respect to the adjustment aspects of a loaded article, therefore the performance requirements have been achieved while using conventional capacity distribution profiles. After the injury, an essential functionality of the absorbent article is to firmly retain the discharged fluids to avoid over-hydration of the wearer's skin. If the absorbent article does not work well in this regard, the liquids that come from the absorbent core return to the skin - also always called "rewet" - can have detrimental effects on the condition of the skin, which for example, can be observed by irritations on the skin. It has been found that when subjected to the collagen rewet test after acquisition, it results in less than 180 mg to provide acceptable performance, but that good performance products provide a performance of less than 80 mg, preferably less than 70 mg or even more preferably less than 50 mg.

Test Procedures General All tests were carried out at around 22 +/- 2 ° C and at 35 +/- 15% relative humidity. The synthetic urine used in the test procedures is commonly known as Jayco SynUrine and is available from Jayco Pharmaceuticals Company of Camp Hill, Pennsylvania. The form of the synthetic urine is: 2.0 g / I of KCl; 2.0 g / l of Na2SO4; 0.85 g / l of (NH4) H2P04; 0.15 g / l of (NH4) H2P04; 0.19 g / l of CaCl2; and 0.23 g / l MgCl2. All these chemicals are reagent grade. The pH of the synthetic urine is within the range of 6.0 to 6.4.

Vertical wicking effect test The vertical wicking effect test is directed to evaluate the time required for a fluid front to reach a certain height in a vertical arrangement, for example against gravity, as well as the amount of fluid collected by the material during this time.

The principle of this test is to place a sample on a sample holder equipped with pin-shaped electrodes, both work to fix the sample in a vertical position and to allow the generation of an electrical signal of time. The container of the fluid is placed on a scale, in such a way that the time dependence of the fluid collected in the sample resulting from the vertical wicking effect can be inspected. While not essential for the sample, the test is run on the basis of commercially available equipment, the EKOTESTER from Ekotec Industrietechnik GmbH, Ratingen, Germany, which also allows electronic processing of the data. The test developed is illustrated schematically in Figures 3 a and b. The equipment is essentially made of perspex, and comprises a water reservoir (310) for holding 929 grams of test fluid at a liquid level height (31 1) of 17 mm and a sample holder (320). This tank is placed on a scale (315) with 0.1 g accuracy, manufactured by Mettler GmbH, type PM3000. Optionally, and indicated through the connection (316), this scale can be connected to an electronic data entry device (342). The sample holder (320) is essentially a perspex plate of a width (330) of 10 cm, a length (331) of 15 cm, and a thickness of about 5 mm (not shown). A fixing means (325) extends beyond these dimensions in the direction (332) which becomes the upward direction during the test to ensure reproducible positioning in the exact vertical direction (eg direction of gravity) to a reproducible immersion depth (333) of the bottom edge (321) of the 12 mm sample holder within the level of the test fluid in the tank (310) during the test. The sample holder (320) is additionally equipped with 9 electrode cathode pins (326), arranged in three rows at distances (334, 335, 336) of 56 mm, 95 mm and 136 mm respectively from the bottom edge ( 321) of the sample holder. There are three electrodes in each of these rows, still spaced at distances (337) of 28 mm apart from each other, and those located on the longitudinal edge (322) being separated at distances (338) of 22 mm separated from these edges. The electrode pins have a length of about 10 mm, a diameter of about 1 mm, and are formed smoothly at their end for simple application of the test. The electrode pins are made of metal. A pin of the anode of the electrode (327) is placed 5 mm next to the pin of the cathode of the middle electrode of the lower row. The anode (327) and the nine cathodes (326) are connected (indicated schematically in Figure 3a) (328) by two cathode pin and anode pin) to a time device (341) that allows to inspect the moment when the electrical circuit between the anode and the individual cathodes is closed, such as by the electrolytic test liquid in a wet sample test that is placed between these electrodes. In contrast to the general procedures outlined above, this equipment is placed and the test is performed in a controlled temperature environment set at 37 ° C and not deviating more than 3 ° C. The test fluid is also prepared at 37 ° C in a temperature controlled water bath for sufficient time to allow constant fluid temperature. With the test fluid the reservoir (310) is filled to have the fluid surface (312) at a level with the required height (311) for example by adding a predetermined amount of fluid, such as 927.3 grams plus / minus 1 gram. The test specimen is equilibrated in laboratory conditions (see above), and placed in the 37 ° C environment just before the test. Also before the test, the caliber of the sample is measured as outlined below.

The test sample is cut to the size of 10 cm by 15 cm by any convenient means that prevents as much as possible the compression effects on the side edges, such as with a sample cutter such as that of JDC Corporation, or sharp cutters like a scalpel or - less preferred - a pair of sharp scissors. The test specimen is carefully placed on the specimen holder in such a way that the edges coincide with the lateral and inferior edges (321 and 322) of the sample holder, for example, as it extends outward from the plate. fastener of the sample. At the same time, the sample must be in an essentially flat arrangement and without efforts, for example, it must not form undulations or be under mechanical stress. Care should be taken that the sample has only directed the contact to the electrode pins and is not contacting the perspex plate of the fastener. This sample holder (320) is then placed in a vertical position within the test fluid reservoir (310), such that the test holder (310) as well as the test spice are immersed exactly within a depth (333) of 12 mm inside the fluid. As a result, the electrodes will now have distances (343, 338 and 339) of 44 mm, 83 mm and 124 mm respectively at the fluid level (312), respectively. Because the immersion of the sample holder does not change the reading of the scale (315), this is caused by a predetermined amount by inserting the sample holder without any sample, for example by 6 grams. It will be known, that the placement of the test fastener (320) and the specimen sample in an untwisted arrangement has to be very precise on one side, but also fast, while the material will begin suction and the wick effect on the first contact with the fluid. Also a part of the EKOTESTER is a frame (350) into which the sample holder can easily be inserted with fastening means (325), but other means can be used to achieve fast and non-tilted fastening. The reading of this scale is inspected as a function of time immediately after sample placement. It has been found advantageous to connect the scale to the computerized equipment (340), such as being part of the EKOTESTER As soon as the fluid reaches the first line and the electrical connection between the anode (327) and the cathodes (326) is closed, these times can be recorded by any means of chronometry, the time unit being a convenient example (341) of the EKOTESTER. While the process of additional data can be done with each of the three time values of a column, the additional data refers to the average of all three electrodes per row, which generally do not deviate more than approximately +/- 5% of the average. Therefore, the data generated are: the amount of fluid dependent on the time that is collected by the sample after immersion, and - the time that the fluid is required to reach certain heights. From this, for each of the heights can read and report two important values: First, the time in seconds until the fluid front reaches the respective heights. Second, to the "cumulative flow" for each of the heights, dividing the amount of fluid collected by the sample in the time in which this height is reached - between this time and between the cross-sectional area defined by the caliber measurement and the width of the sample of 10 cm.

Proof of Acquisition Referring to Figure 4, an absorbent structure (410) is loaded with a 75 ml stream of synthetic urine at a rate of 15 ml / s using a pump (Model 7520-00 supplied by Cole Parmer Instruments., Chicago, USA) , from a height of 5 cm above the surface of the sample. The time to absorb the urine by a chronometer is recorded. The jet is repeated at jet intervals of precisely 5 minutes until the article is sufficiently loaded. The current test data is generated by loading four times. The test samples, which can be a complete absorbent article or an absorbent structure comprising an absorbent core, a topsheet, and a backsheet, is arranged to rest flat on a foam pad 411 within a perspex box (of which only shows the base 412). A perspex plate 413 having an opening diameter of 5 cm in half is placed on top of the sample over the load zone of the structure. Synthetic urine is introduced to the sample through a fitted cylinder 414, and stuck into the opening. The electrodes 415 are located on the lowest surface of the plate, in contact with the surface of the absorbent structure 410. The electrodes are placed on the chronometer. The loads 416 are placed on top of the plate to simulate for example a baby's weight. A pressure of about 50 g cm2 (0J psi) is reached to place the weights 416, for example for the commonly available MAXI size of 20 kg.

While the test fluid is introduced into the cylinder it typically accumulates on top of the absorbent structure whereby an electrical circuit between the electrodes is completed. The test fluid is transported from the pump to the test assembly by means of an 8 mm diameter tube, which is kept full with the test fluid. Then, the fluid begins to leave the tube essentially at the same time the pump starts to operate. At the same time, the stopwatch is also activated, and the stopwatch stops when the absorbent structure has absorbed the urine stream, and the electrical contact between the electrodes breaks. The acquisition speed is defined as the volume of the jet absorbed (ml) per unit of time (s). the acquisition speed is calculated for each jet that is introduced into the sample. The first and the last of the four jets are of particular interest in view of the current invention. This test is primarily designed to evaluate the products that are generally referred to as MAXI size products for a design capacity of around 300 ml, and that have an Ultima Storage Capacity of around 300 ml to around 400 ml . Products with significantly different capacities should be evaluated (such as can be anticipated by adult incontinence products), the particular setting of the fluid volume per jet should be adjusted appropriately to about 20% of the total capacity of the product. design of the article, and the standard protocol deviation from the sample should be recorded.

Post-Acquisition Collagen Rewet Method Before running the test, the collagen film purchased from NATURIN GmbH, Weinhein, Germany, under the designation COFFI and a basis weight of about 28g / m2 is prepared by being cut into 90 mm diameter sheets for example using a device for cutting the sample, and balancing the film in the controlled environment of the test room (see above) for at least 12 hours (tweezers will be used for all manipulations of the collagen film). At least 5 minutes, but no more than 6 minutes after the last jet of the acquisition test above, the cover layer and weights are removed, and the test sample (520) is carefully placed flat on a table top. laboratory work Four sheets of cut and balanced collagen material (510) are weighed to an accuracy of one milligram, and then placed centered on the loading point of the article, and covered by perspex plate (530) 90 mm in diameter, and about 20 mm thick. A weight (540) of 15 kg (also centered) is added carefully. After 30 +/- 2 seconds the weight and the perspex plate are again carefully removed, and the collagen films are reweighed. The result of the Rejuvenation Method of Collagen after Acquisition is the collection of moisture from the collagen film, expressed in mg. Additionally it should be noted, that this test protocol can be easily adjusted according to the specific product types, such as different sizes of baby diapers, or adult incontinence articles, catamenial articles, or by variation in type and amount of fluid loading, the amount and size of the absorbent material, or variations in the applicable pressure. Once these relevant parameters have been defined, such modifications will be obvious to one skilled in the art. When the results of the adjusted test protocol are considered, the products can easily be optimizing these relevant parameters identified as in an experiment designed according to standard static methods with realism in the use of boundary conditions.

Fluid distribution test The fluid distribution test is directed to determine the amount of liquid collected by a certain part of the absorbent article or core structure. This test can be applied to items loaded under controlled laboratory conditions, such as when performing other liquid handling aptitude assessment tests, for example the acquisition test as described above. This test can also be applied to used items such as when the babies wear the diapers, they load them under real conditions of use, after which the article is evaluated under the appropriate hygienic conditions. The waiting time between loading and evaluation should not be too large, thought to have been found - at least for the designs as tested in the examples described above - the waiting time only has very little impact on distribution results. fluid. In order to determine the distribution of fluids in an absorbent structure or article, the loaded article is weighed and then placed flat (optionally after cutting through the elastic legs to facilitate flattening) and marked throughout its length. longitudinal axis in rooms. Afterwards, the article is cut along lines perpendicular to the longitudinal line, so care must be taken not to squeeze the liquid. This can be best achieved by using a JCD paper cutter or a scarf. Each segment is weighed, and the estimated result to the total weight.

For articles that have a strong profile (for example different weights of material in different sections), the total weight as well as the sectional weights can be adjusted by the dry weight of the article. To do this, sectional weights must be determined by "sister diapers" (eg diapers made in the same way, and - if they are made in a large-scale production line - in at least the same time as the diaper tested. So if the total article has different weights, the sectional weights can also adjust according to this portion, now assuming, that the deviations will be proportionally extended through all the sections.The result of the fluid distribution tests is expressed as a percentage of the total amount of fluid that occurs in certain sections, such as the crotch region.

Base weight / gauge / density measurement An example of a defined area such as cutting with a sample cutter is weighed with at least 0.1% accuracy. The gauge is measured under an applied pressure of 550 Pa (0.08 psi) for a 50 mm diameter test area. The basis weight as weight per unit area expressed in g / m2, the caliper expressed in mm @ pressure of 550 Pa and the density expressed in g / cm3 can be easily calculated.

Tea Bag Centrifugal Capacity Test (CCBT test) Although the CCBT test was developed specifically for superabsorbent materials, it can be easily applied to other absorbent materials.

The Centrifugal Capacity test of the Tea Bag measures the values of the Centrifugal Capacity of the Tea Bag, which are a measure of the retention of the liquids in the absorbent materials. The absorbent materials are placed inside a "tea bag", immersed in a solution at 0.9% by weight of sodium chloride for 20 minutes, and then centrifuged for 3 minutes. The ratio of the weight of the liquid retained to the initial weight of the dry material is the absorbent capacity of the absorbent material. Two liters of sodium chloride at 0.9% by weight in distilled water are poured into a tray having dimensions 24 cm X 30 cm X5 cm. The height that fills the liquid should be around 3 cm. The pouch of the tea bag has dimensions of 6.5 cm X 6.5 cm and is available from Teekanne in Dusseldorf, Germany. The pouch is heat sealable with a standard kitchen plastic bag sealing device (for example, VACUPACK2 PLUS from Krups, Germany). The tea bag is opened by carefully cutting it partially, and then weighing it. About 0.200 g of the sample of the absorbent material, weighed to the nearest +/- 0.005 g, is placed inside the tea bag. Then, the tea bag is closed with a heat sealer. This is called the sample tea bag. An empty tea bag is sealed and used as a white. Then, the sample tea bag and the white tea bag are placed on the surface of the saline, and immersed for about five seconds using a spatula to allow complete wetting (the tea bags will float on the surface). of the saline solution but then they will be completely wet). The stopwatch is activated immediately. After the 20-minute soaking time the sample tea bag and the white tea bag are removed from the saline, and placed in a Baunknecht WS130, Bosch 772 NZK096 or equivalent centrifuge (230 mm diameter), of so that each bag adheres to the outer wall of the centrifugal basket. The centrifugal cap closes, the centrifuge is activated, and the speed increases rapidly up to 1, 400 rpm. Once the centrifuge stabilizes at 1, 400 rpm the timer is activated. After three minutes, the centrifuge stops. The sample tea bag and the white tea bag are removed and weighed separately. The Tea Bag Centrifugal Capacity (CCBT) for the sample of the absorbent material is calculated as follows: CCBT = ((weight of the tea bag after centrifuging) - (weight of white tea bag after centrifugation) - ( weight of dry absorbent material)) / (weight of dry absorbent material). As well, the specific parts of the structures or of the total absorbent articles can be measured, such as "sectional" cut, for example to observe in parts of the structure or of the total article, by where the cut is made through the complete width of the article at certain points of the longitudinal axis of the article. In particular, the definition of "crotch region" as described above allows determining the "crotch region capacity". Other cuts can be used to determine a "base capacity" (for example the amount of capacity contained in a unit area of the specific region of the article.) Depending on the size of the area unit (preferably 2 cm by 2 cm) the definitions of how many average is taking place - naturally, the smaller average will occur, the smaller one.

Ultimate Storage Capacity In order to determine or evaluate the Ultimate Storage Design Capacity, a number of methods have been proposed.

In the context of the present invention, it is assumed, that the Ultimate Storage Capacity of an article is the sum of the ultimate absorbent capacities of the individual elements or material. For these individual components, several well-stabilized techniques can be applied as long as they are applied consistently throughout the comparison. For example, the Tea Bag Centrifugal Capacity as developed and well stabilized for superabsorbent polymers (PAS) can be used for such PAS materials, but also for others (see above). Once the capacities for the individual materials are known, the total capacity of the article can be calculated by multiplying these values (in ml / g) with the weight of the material used in the article. For materials that have a dedicated functionality other than the last storage of fluids - such as acquisition layers and the like - the final storage capacity can be neglected, whether such materials actually have very low capacity values compared to the materials of Last storage of dedicated fluids, or such materials are proposed not to be loaded with fluid, and then they must release their fluids to other materials of last storage.

Examples and Evaluation.

Distribution Materials To compare various designs and material properties, two materials have been used to replace a conventional tissue, such as a high moisture resistance tissue of 22.5 g / m2 base weight produced by Strepp, Kreuzau, Germany under reference NCB. The physical liquid transport properties for such tissues are listed in Table 1.

First, a high-flux distribution material (Example 1.1) was evaluated which has been made starting from a chemically placed wet laid frame having a basis weight of 150 gsm and a density of 0.094 g / cm 3, which consists of a fiber mixture of: - 90% by weight (of the fiber mixture) of twisted, chemically hardened cellulose (CS), commercially available under the designation "CMC" from Weyerhaeuser Co., EU; 10% by weight (of the fiber mixture) of eucalyptus type fiber, bound by 2% by weight of fiber blend of a glyoxal-polyacrylamide resin marketed by Cytec Industries, West Patterson, NJ. USA, under the trade name of Parez ™ 631 NC. This has been subjected to a post-formation treatment between two rollers in a depth of overlap of the peaks of 0.2 mm with a width of 1 tooth of 0.6 mm, being 1.0 mm apart, as described in more detail in the European Application 96108427.4. An additional thermally bonded wet laid material (Example 1.2) has been made using 60% of the chemically cured twisted cellulose, 30% of said eucalyptus fibers as used in the chemically bonded distribution material described above, and 10% of fibers BiCo PET core / PE shell that has a permanent hydrophilizer incorporated into the PE resin, produced by HOECHST CELANESE EU, under the designation of Celbond® T255. After conventional wet deposition, this web has been thermally bonded by air binding technology by Ahistrom Inc. EU, at a basis weight of 150 gsm and a density of 0.11 g / cm 3.

When subjected to the Vertical Wick Effect Tests as described below, the materials showed the results as shown in the table 1: Table 1 Example 1.1 Example 1.2 Example 1.3 Time (sec) of the wick effect to reach 8.3 cm 13 sec 45 > 210 12.4 cm 45 sec 165 not reached Flow (ml / sec / cm2) in 8.3 cm 12.4 cm 0.32 0.06 < 0.02 0.16 0.04 not reached Therefore, Example 1.2 provides improved performance over the conventional tissues of Example 1.3 which, however, is still significantly less than those of the particularly preferred material of Example 1.1.

General Product Description While the present invention is applicable to a wide range of products, the particular benefits have been exemplified in the context of baby diapers, and so for diapers proposed for babies in the range of 8 to 18 kg, also called of size "MAXI". For such products, the typical dimensions are those of PAMPERS BABY DRY PLUS MAXI / MAXI PLUS, such marketed by Procter & Gamble through several countries in Europe: Length Width (x direction) (direction y) total diaper 499 mm 430 mm absorbent core 438 mm core loop width 115 mm "crotch" core 102 mm During use, the design of such articles is such that it essentially adjusts symmetrically when comparing the extensions within the waist regions from front to back. The crotch point coincides with the "loading point", placed (both for boys and girls) at 4.9 cm towards the front waist region of the mid-section point of the article and 17 cm from the front edge of the core. Consequently, the crotch region extends - when starting to count from the front end of the waist of the absorbent core (at 0 cm) to the rear end (at 43.8 cm) - from 6.1 cm to 27.8 cm. The products exemplifying the present invention are generally derived from those commercially available products, and then modified as outlined in the specific examples. These products contain in the storage core around 20 g of conventional air filter of northern tender wood, and about 10 g of superabsorbent material such as one commercially available from Stockhausen GmbH, Germany under the trademark FAVOR SXM, type 100. The superabsorbent material has a theoretical capacity of 31 ml / g, which together with 4 ml / g for the air filter provides a design capacity for such articles of around 390 ml. Additionally, the core comprises an "acquisition patch" that overlaps the storage core over a length of 25.4 cm, starting from 28 cm away from the front edge of the core to the rear. This patch is made of chemically hardened air-laid cellulosic material (CS) supplied by Weyerhaeuser Co., USA under the trade designation "CMC" which functions as a distribution / acquisition layer having a basis weight of about 295 g. / m2. In the context of the present exemplification the final storage capacity of these materials is set at zero, while it is assumed that the fluid is removed from this distribution / acquisition layer so that this layer is ready for recharging in repeated jets (see above). The design of the core is such that a mixture of PAS and air filter is overlapping (in the direction towards the user) a thin layer of pure air filter. The shape of the core is almost rectangular with a size of 438 mm by 115 mm, with a width slightly narrower at the point of the crotch that has a width of 102 mm. The mixed layer is profiled in basis weight, such as a longitudinal capacity distribution profile is approximately as follows: 1st quarter (front) 140 ml 2nd quarter 130 mi 3rd quarter 70 ml 4th quarter (rear) 50 ml Adjustment Improvements The first test is aimed at supporting the effect of redistribution only of storage capacity. To do this, an "adjustment study" has been conducted, in which two products have been produced in pilot production facilities. First, a reference product was made that directs the replication of the commercial product as described above, which differs from the latter by not having an acquisition patch. This product was compared with an "inverse profile" design example 2.1 that differs only in that the capacity profile was executed in faces in a different way, so that the capacity profile is as follows: 1st quarter (front) 120 ml 2nd room 70 ml 3rd room 60 ml 4th room (back) 140 ml These have been tested in an "adjustment study". Whereby, the test and the reference products were artificially loaded with synthetic urine, and the adjustment range of the experienced mothers was recorded, each for the dry diaper, and when loaded, first with 150 ml, and then with 300 ml of synthetic urine. For each product, the classification of "global" adjustment and the classification of "adjustment between the legs" of several loads has been questioned. The classification was categorized on a scale from 0 (poor) to 4 (excellent). The products were placed among 17 randomly selected babies. Table 2 Example 2.2 Example 2.1 Mother adjustment range Overall adjustment 2.6 2.0 Adjustment between legs When dry 3.0 2.0 to 150 ml 2.9 1.9 to 300 ml 2.6 1.4 This clearly shows the poorer fit assessment of a conventionally profiled diaper in contrast to a reverse profiled diaper. Impact on the performance of the inverse profile (mixed cores) However, consumers do not want to compromise performance for improvements in the adjustment. To evaluate the impact of various designs on performance, products have been compared in laboratories testing the highly relevant parameter of fluid acquisition and rewet performance.

For this test, products have been produced in a complete line of pilot scale, with a reference product that replicates the designs of current commercial products (example 3.1), except to have the acquisition patch being replaced by a synthetic acquisition layer attached through air made by air-depositing 63% of eccentric BiCoPP / PE fibers (ESEWA ex Danaklon AB, DK code) together with 37% of conventional southern softwood pulp in a weft and attaching through air to a density 0.04 g / cm3, at a base weight of 120 gsm (example 3.3). The following product is a combination of Example 3.3 with the inverse capacity profile as described in Example 2.1. The third product example 3.1 differentiated from the latter which additionally comprises a material deposited in thermally bound moist as described in example 1.2.

Table 3 Ex. 3.1 Ex. 3.2 Ex. 3.3 Reverse side distribution crotch capacity Air-bound (all) acquisition fabric Material placed in wet distribution through conventional tissue for amboe air Fluid distribution (%) crotch 58 55 79 Acquisition test (ml / sec ) 1st jet 2.9 3.6 3.2 4th jet 0.19 0.10 0.16 Kepumeaecirnie nto of collagen (mg) crotch 265 283 262 Back 25 72 12 These data show that - while the inverse profile by itself improves the distribution of fluids by providing less capacity in the crotch area - this benefit is compromised by performance poorer rewetting, particularly with the back of the article. Using an improved fluid distribution material actually improves its drawbacks without detrimentally impacting fluid distribution or acquisition performance.

Impact of conventionally profiled core distribution material The benefit performance of good distribution materials is further exemplified in the reverse profile cores. To underline this effect, a conventional diaper (example 4.2, same design as Example 2.2) has been compared to Example 4.1, wherein the conventional tissue has been replaced by an improved dispensing material (as described in Example 1) . Table 4 Example 4.1 Example 4.2 Fluid distribution (%) Crotch 91 88 Acquisition test (ml / sec) 3.9 4.8 1st jet 0.59 0.82 4th jet Re-wetted collagen (mg) 60 53 Crotch Therefore, the improved fluid distribution material actually improves performance, however it does so by changing the fluid distribution only to a very limited extent.

Layered cores The benefits of the present invention have additionally been demonstrated in a test matrix where the cores have been made in a pilot line without core mixed fluff / superabsorbent, but the change with layered structures. The overall design was the same as in Examples 3, whereby the absorbent core was designed and made differently by replacing the homogenously mixed storage core with a rectangular absorbent structure with 15 g of superabsorbent powder being sandwiched between the layers of one of the conventional tissues of the chemically modified bound distribution material with post-formation treatment. The superabsorbent laminate has a width of 90 mm (centered) using a glue lamination technique sprayed, a method as described in more detail in the above-mentioned EP-A-0.605.541. For two designs (referred to as "flat"), the laminate spread across the entire full length of the article, with a super absorbent basis weight of 355 gsm. For two reverse profile designs, the laminates extended from both edges of the front and rear core at a basis weight of 500 gsm over a length of 167 mm towards the crotch region, then leaving about 130 mm in the middle section of the article free superabsorbent. As the last one is pulled to the front, a part of the crotch region is essentially free superabsorbent. Table 5 5.1 5.2 5.3 5.4 Profile of rev. Flat Rev. Plane capacity High flow material Conv. high flow conv. average distribution average average Proof of acquisition (ml / sec) 1st jet 3.95 2.92 3.91 2.89 4th jet 0.66 0.36 0.73 0.54 Re-wetted collagen (μg) Crotch 59 118 65 106 back Fluid distribution (%) crotch 56 58 70 73 This table also demonstrates the beneficial effect of good distribution materials on the performance of the article: it further demonstrates that - independently of the tissue or high flow material - the distribution of the fluid is positively impacted by the design of the inverse profile. However, clearly, rewetting is mostly compromised for tissue products. The overall conclusion of these experiments can be summarized, that a preferred product has small final storage capacity in the crotch region, a material of good distribution, preferably a material of high fluid flow distribution, such that the product still exhibits good performance in fluid handling as measured by rewet and / or acquisition values.

Claims (26)

Claims

1. Absorbent article comprising an absorbent core comprising a crotch region and one or more waist regions, wherein said crotch region has a lower fluid storage capacity than said one or more waist regions together, characterized in that said article has an Acquisition performance of at least 0.5 ml / sec for the fourth jet.

2. An absorbent article according to claim 1, wherein said article has an Acquisition performance of at least 0.6 ml / sec for the fourth jet.

3. An absorbent article according to any of claims 1 or 2, wherein said article has an Acquisition performance of at least OJ ml / sec for the fourth jet.

4. An absorbent article according to any of claims 1 to 3, wherein the article has an Acquisition performance of at least 3.75 ml / sec for the first jet.

5. An absorbent article according to any of claims 1 to 4, wherein the article has an acquisition performance of at least 4.0 ml / sec for the first jet.

6. An absorbent article according to any of claims 1 to 5, wherein the article has an Acquisition performance of at least 4.2 ml / sec for the first jet.

7. An absorbent article according to any of claims 1 to 6, wherein said crotch region has a last base fluid storage capacity of less than 0.9 times the average base storage capacity of average fluid of the absorbent core.

8. An absorbent article according to any one of claims 1 to 7, wherein said crotch region has a final base storage capacity of fluid of less than OJ times the ultimate base storage capacity of average fluid of the absorbent core.

An absorbent article according to any of claims 1 to 8, wherein said crotch region has a last base fluid storage capacity of less than 0.5 times the last base storage capacity of average fluid of the absorbent core.

An absorbent article according to any of claims 1 to 6, wherein said crotch region has a last base fluid storage capacity of less than 0.3 times the last base storage capacity of average fluid of the absorbent core.

11. An absorbent article according to any of claims 1 to 10, wherein said crotch region has a last sectional fluid storage capacity of less than 49% of the final total fluid storage capacity of the core.

12. An absorbent article according to any one of claims 1 to 10, wherein said crotch region has a sectional ultimate sectional fluid storage capacity of less than 41% of the final total fluid storage capacity of the core.

An absorbent article according to any one of claims 1 to 10, wherein said crotch region has a sectional ultimate sectional fluid storage capacity of less than 23% of the final total fluid storage capacity of the core.

14. An absorbent article according to any of claims 1 to 13, further characterized in that the length of the crotch region is half the length of the total absorbent core.

15. An absorbent article according to any of claims 1 to 14, further characterized in that it comprises a final fluid storage material that provides at least 80% of the total final storage capacity of the absorbent core.

16. An absorbent article according to claim 15, further characterized in that said last fluid storage material provides at least 90% of the total final storage capacity of the absorbent core.

17. An absorbent article according to claim 15 or 16, further characterized in that said last fluid storage material comprises superabsorbent polymers.

18. An absorbent article according to claim 15 or 16, further characterized in that said last fluid storage material comprises non-superabsorbent polymers.

19. An absorbent article according to claim 15 or 16, further characterized in that said last fluid storage material comprises an open cell absorbent foam material.

20. An absorbent article according to claim 19, wherein said absorbent foam materials are derived from a high internal phase water-in-oil emulsion.

21. An absorbent article according to any of the preceding claims, further characterized in that at least 50% of the area of said crotch region essentially does not contain final storage capacity.

22. An absorbent article according to any of the preceding claims, further characterized in that less than 50% of said final storage capacity is placed in advance from the crotch area in the front half of the article, and more than 50% of said last storage capacity is placed in the back half of the article.

23. An absorbent article according to claim 22, wherein less than 33% of said final storage capacity is placed in advance from the crotch / in the front half of the article, and more than 67% of said Last storage capacity is placed in the back half of the article.

24. An absorbent article according to any of the preceding claims, further characterized in that it has in said crotch region a collagen rewet performance subsequent to the acquisition of less than 180 mg.

25. An absorbent article according to any of the preceding claims, wherein said crotch region comprises a material having a flow at 12.4 cm or greater than 0.075 g / cm2 / sec.

26. An absorbent article according to any of the preceding claims wherein said crotch region comprises a material which is obtained by a post-formation treatment of a chemically bonded wet laid web comprising hardened cellulose fibers, fibers of type of eucalyptus and chemical binder resin.