MXPA02005020A

MXPA02005020A - Absorbent cores with y density gradient.

Info

Publication number: MXPA02005020A
Application number: MXPA02005020A
Authority: MX
Inventors: Kalmon Michael
Original assignee: Bki Holding Corp
Priority date: 1999-11-19
Filing date: 2000-11-17
Publication date: 2003-05-23
Also published as: AU1619201A; EP1242017A1; WO2001035886A1; CA2391528A1; WO2001035886A8; CO5200786A1; PE20010655A1; TW567061B; AR026549A1

Abstract

Disclosed are absorbent structures having y directional profile in density and superabsorbent polymer particle content. The structures include zones having higher density and higher superabsorbent polymer particle content and zones having lower density and lower superabsorbent polymer particle content. Also disclosed are methods for preparing absorbent structures having y directional profile in density and superabsorbent polymer content.

Description

ABSORBENT NUCLEI WITH GRADI ENTE DENSI DAD AND Related Requests This application claims the benefit of provisional US patent application no. 60/1 66,489 filed November 1, 1999; the provisional US patent application no. 60/21 1, 090 filed on June 2, 2000 and the provisional US patent application no. 60/21 1, 091 filed on January 2, 2000, all incorporated herein by reference.

FIELD OF THE INVENTION This invention is directed to the field of unitary absorbent structures for use in absorbent articles, in which one or more layers of the absorbent structure are profiled in the y-direction, in one or more of the basis weight properties. , content of functional particles, or density, and processes for the production of the structure.

BACKGROUND OF THE INVENTION Absorbent structures are used in a wide range of disposable absorbent articles, including baby diapers, adult incontinence products, sanitary napkins and the like. These and other absorbent articles are generally provided with an absorbent structure, which is arranged as a core, to receive and retain body fluids. The absorbent core is usually inserted between a liquid-permeable upper sheet, whose function is to allow the passage of fluid to the core and a liquid-impermeable backsheet, whose function is to contain the fluid and prevent it from passing through the absorbent article to the wearer's garment of the absorbent article. An absorbent structure, which is used as a core for adult incontinence pads and pads, often includes fibrous blocks or frames constructed of cellulosic, hydrophilic, fluffed, loose, defibrillated fibers. The core may also include functional particles, such as superabsorbent polymer particles ("SAP"), glands, flakes or fibers (collectively "particles"). In recent years, the demand in the market for an absorbent article has grown increasingly thinner and more comfortable. Such an article can be obtained by decreasing the thickness of the structure used as the diaper core, by increasing the amount of functional particles, and by calendering or pressing the core to reduce the caliper and hence increasing the density. However, higher density items used as cores do not absorb liquid as rapidly as lower density cores, because densification of the nucleus results in a smaller effective pore size. Accordingly, in order to maintain the proper absorption of liquids, it is necessary to provide a low density layer having a larger pore size above the high density absorbent core to increase the rate of uptake of the liquid discharged onto it. absorbent article. The low density sheet is usually referred to as an acquisition layer.

Multi-strand absorbent core designs involve a more complicated manufacturing process. The storage sheet portion of a disposable diaper, for example, is generally formed in its place, during the conversion process, from loose, fluffed cell. Such cellulose material is generally not available in the form of a preformed sheet because it exhibits insufficient weft strength, due to its lack of bonding or entanglement between fibers, to be unwound or directly deflated on and handled in equipment for making absorbent pads. . Some absorbent articles, such as ultra-thin female towels, are generally produced from unwoven material based on rolled products. Such a roll of preformed absorbent core material is unwound directly as a feed into the equipment for converting absorbent articles without the defibrillation step usually required for products based on fluff., such as diapers and incontinence incontinence pads. The nonwoven web is usually bonded or consolidated in a way that gives it enough strength to be handled during the converting process. The absorbent structures made of such nonwoven webs may also contain SAP particles. However, these absorbent structures are often inefficient in cases where a demand is for the acquisition and absorption of large quantities or a surge of bodily fluids. In these cases, a simple sheet absorbent material is often not sufficient to serve as the absorbent core, because the liquid is not distributed in the structure throughout the process. absorbent core length. As a result, regions of the absorbent core remain unused. The frame consolidation mechanism used in the approximation of rolled products to make preformed cores provides strength and dimensional stability to the weft. Such mechanisms include latex binding, joining with thermoplastic or bicomponent fibers or thermoplastic powders, hydroentangling, needle puncturing, carding or the like. However, such bonded materials provide a relatively rigid core, which often does not conform well to the shape of the human body, especially in those situations where there is a demand for the product to adjust to acquire and contain large volumes of body fluids. . The flexibility and softness of the absorbent core are necessary to ensure that the absorbent core can easily conform itself to the shape of the human body or to the shape of a component, eg, another absorbent layer, of the absorbent article adjacent to the absorbent article. he. This avoids, in turn, the formation of openings and channels between the absorbent article and the human body or between various parts of the absorbent article, which could otherwise cause undesirable leaks in the absorbent article. The integrity of the absorbent structure used as a core is necessary to ensure that the absorbent core is not deformed and exhibits discontinuities during use by a consumer. Such deformations and discontinuities can lead to a decrease in absorbency and overall capacity and an increase in an undesirable leak. The previous absorbent structures have been deficient in one or more of flexibility, integrity, profile absorbency and capacity. For example, a conventional core pulp core has good conformability due to its high flexibility and softness, but at the same time it can easily disintegrate during use, due to its poor integrity. As another example, certain bonded cores, such as air suspended cores made of pulp of densely packed cellulose at a density greater than 0.35 g / cc have dry integrity, but have no wet integrity and poor formability. Absorbent structures having improved softness and flexibility have been described in international patent application WO 00/41 882, published on July 20, 2000. However, there is still a need to further intensify the capacity of such structures. structures by incorporating large amounts of SAP particles and, at the same time, maintaining a high fluid acquisition efficiency of such structures. The absorbent structures made of nonwoven webs may contain SAP particles to obtain sufficient absorbent capacity. However, there are practical ways to increase the proportion of SAP particles in a commercially available absorbent structure. If the concentration of SAP particles in an absorbent structure used as a core is too high, a blockage of gel may result and the speed to acquire and redistribute the liquid within the core will become too slow for satisfactory performance of the core. absorbent core. As the adjacent SAP particles swell, they form a free liquid barrier not immediately absorbed by the SAP particles. As a result, access by liquid to SAP particles not exposed can be blocked by the swollen, gelled SAP particles. When the gel block occurs, a liquid deposit, opposite to the absorption, takes place in the nucleus. As a result, large portions of the core remain unused and a failure (leakage) of the absorbent core can occur. Gel blockage caused by high concentrations of SAP particles results in reduced core permeability, or fluid flow, particularly under pressures encountered during the use of the absorbent product. A way to mimic the gel block and maintain core permeability for efficient fluid uptake and redistribution, is limiting the ratio of SAP particles to matrix fibers in the absorbent structure used as the core. In this way, there is sufficient separation between particles, so that even after the particles have been impinged by exposure to the liquid, they do not contact adjacent particles and the free liquid can migrate to non-exposed SAPs. Unfortunately, limiting the concentration of SAP particles in the absorbent core also mimics the thickness at which the core can become thinner and more comfortable. To avoid gel blockage, commercial absorbent cores are currently imitated at concentrations of SAP particles of 20 percent to 50 percent by weight of the core. However, even with this concentration limit of SAP particles, these absorbent cores have poor fluid acquisition rates. Absorbent structures used as cores in absorbent, disposable, commercial, current articles are constructed at Combine several sheets of material in the converter line. Normally, these multi-sheet absorbent cores contain one or more sheets of varying width, wherein at least one sheet in the absorbent core is narrower than the full width of the core. The narrow sheet is present in these commercial absorbent cores to improve performance and reduce raw material costs by focusing absorbent material where it is most needed, and removing material where it is not necessary. The existing technique for the manufacture of absorbent cores, which are profiled in basis weight, involves combining several plies or structures of absorbent material in the converter line to manufacture absorbent cores in layers. Normal airborne forming materials for the manufacture of absorbent structures to be used as cores, contain mechanical equipment on one side of the full width forming wire designed to accept absorbent material suspended in air and uniformly distribute the absorbent material. on the forming wire. Normally, located on the other side of the forming wire, and working in conjunction with the distributor equipment, there is a vacuum system that is present to collect the absorbent material suspended in air on the forming wire.

BRIEF DESCRIPTION OF THE INVENTION It would be highly desirable to provide an absorbent structure to be used as a core, which is capable of supporting an SAP particle concentration of about 1.0 percent to 80 percent in weight, preferably about 30 percent to 80 percent by weight, while maintaining a fast fluid acquisition speed and core stability. It would also be desirable to provide a moisture-stable absorbent core, which exhibits improved storage efficiency and storage for a given concentration of SAP. The present invention provides an increase in conversion efficiencies by using unitary absorbent structures comprising several layers of absorbent material. The applicants have now discovered a method for simplifying the manufacture of absorbent products containing profiled absorbent cores. In a first embodiment, a profiled core can be obtained by using a forming surface, which can be physically blocked with a mask to prevent absorbent material from depositing in specific areas, resulting in the formation of an absorbent structure with profiled strata. In an alternative modality, a profiled structure can be obtained by controlling the vacuum system by using a block for the vacuum system. The block can be placed in the operation of forming unit suspended in air between the vacuum system and the forming wire. An object of the invention is to provide a unitary absorbent core comprising one or more layers of absorbent material, in which one or more of the basis weight properties, containing functional particles, or density of at least one of the strata is profiled in the y-direction.

Another object of the invention is to provide a process for manufacturing absorbent cores comprising one or more layers, in which one or more of the basis weight, functional particle content, or density of at least one of the layers is profiled in the address-y. A further object of the invention is to increase conversion efficiencies by producing absorbent cores via the air suspension process versus producing multi-sheet absorbent cores in the converter line by melting various absorbent materials. Another object of the invention is to introduce density g in the direction-and in unit absorbent cores. A further objective of the invention is to provide greater control over the attributes of absorbent cores an itarios, thus providing product developers with greater flexibility. Additional objects of the invention are to improve the performance of the product by placing absorbent material in unitary absorbent cores where it is most effective, or removing absorbent material in absorbent nuclei where it is not effective. Another object of the invention is to form absorbent cores having improved fluid acquisition and containment, as well as reduced leakage potential. A further object of the invention is to simplify the final product converting processes by reducing the number of sheets in the absorbent structure.

In a first embodiment, the present invention is directed to absorbent structures having a profile and direction, comprising a stratum or a plurality of strata, at least one stratum of which is produced by a continuous series of unit operations, and which contains functional particles and has a y-directional profile. The stratum produced by a continuous series of unitary operations comprises first and second areas located in contact with one another, wherein the first zone has one or more of a greater density, a higher content of functional particles and a greater base weight than the second zone. In a second embodiment, the present invention is directed to absorbent structures comprising functional particles and having a fluid acquisition and storage efficiency (PHASE), as defined herein, of more than about 50. In this modality , the structure has a y-directional profile, and comprises a stratum or a plurality of strata, wherein at least one stratum comprises first and second zones disposed in contact with each other, wherein the first zone has one or more of a higher density a greater content of functional particles and a greater basis weight than the second zone. In further embodiments of the first and second embodiments, the invention is directed to structures that have a first zone that has a higher density and a higher basis weight than the second zone, or structures that have a higher density and content of functional particles than the second zone. In certain modalities, the first zone is disposed at the lateral edge of the absorbent structure. In additional modalities, the structures comprise third and fourth zones, where the third zone has a higher density and higher content of functional particles than the second and fourth zones. In particular modalities of the structures described above, the structure comprises a plurality of layers, wherein at least one layer has a larger surface area, which is less than 80 percent of the surface area of a corresponding larger surface area. another layer. In certain embodiments, the y-directional profile of the structures of the invention may be the result of a single stratum having a y-directional profile, or the y-directional profile may be the result of a plurality of strata having a profile and-directional. In addition, at least one of the strata may be of substantially uniform density or basis weight. In particular modalities, the structure may also have a z-d directional profile. In the embodiments described above, the structures may comprise fibers, both natural and / or synthetic fibers. Suitable fibers include fibers that have a water retention value of at least 80 percent, and fibers that have a curl of at least 25 percent. In the modalities described above, the structures may comprise a binder, including a liquid binder (such as a latex binder), thermoplastic powders, thermoplastic fibers, bicomponent fibers and mixtures of the same. The binder can, for example, to be present in the amount of about 0 1 percent to about 10 percent of the structure The invention also applies to the above embodiments, further comprising an acquisition layer in fluid communication with the first zone, the second zone or both. with the first zone and the second zone The acquisition stratum can comprise fibers of a random matrix with a binder, wherein the matrix fibers can have a length from about 2 to about 15 mm In any of the above embodiments, the basis weight of the first zone is from about 50 gsm to about 1,000 gsm. The basis weight of the second zone can be from about 0 1 gsm to about 800 gsm. In certain aspects of the invention, the density of the first zone can be from about 0 1 5 g / cm 3 to about 0 25 g / cm 3 Additionally, in certain aspects of the invention, the content of functional particles can be about 10 percent up to about 90 percent by weight, and / or the content of functional particles in the second zone can be from about 0 percent to about 70 percent by weight. In particular embodiments of the structures described above, the PHASE value is greater than about 80. The structure can also be have a wet integrity greater than about 4 0 mN / g m, a softness greater than about 8.0 / J, or a flexibility greater than about 70 / N. In particular embodiments of the structures described above, the structure is produced by a continuous series of unitary operations, wherein each stratum is formed in an itary operation from one or more selected materials of fibers, functional particles, binders, tissue carrier and additives. The present invention is also directed to disposable absorbent articles, comprising: (A) an upper liquid-permeable sheet, (B) a liquid-permeable foil back sheet, (C) between the upper sheet and the back sheet, and in fluid unication with the top sheet an absorbent structure as described above, the structure comprising a stratum or plurality of strata, at least one stratum containing functional particles, the absorbent structure having a y-directional profile comprising first and second zones arranged in contact with each other, wherein the first zone has one or more of a greater density, a higher content of functional particles and a greater basis weight than the second zone, and optionally, (D) between (C) and (B) ) and in fluid com- munication with (C), a storage stratum that comprises fibers and functional particles where a surface greater than (C) in fluid communication with a larger surface area of (D) has a surface area, which is less than 80 cent of the surface area of a corresponding larger surface area of (D) In particular embodiments, the absorbent structure (C) may comprise (1) a y-directionally adsorbed stratum; and (2) a y-directionally profiled acquisition and storage stratum that has a higher content of functional particles than that of the acquisition stratum. The items described above may be children's diapers, underpants, incontinence devices for adults or feminine towels. In particular embodiments, the articles of the invention may have a PHASE of 50 or more, preferably 80 or more, more preferably 1000 or more. In certain aspects, the structures of the present invention can be manufactured by suspending absorbent material in a fluid and depositing the material on a porous forming surface or forming wire. The suspension fluid for the absorbent material may be water or air, but preferably it is air. Placing several unit forming operations in series provides the formation of unitary absorbent structures comprising several strata of absorbent material. Normal air suspended training operations contain mechanical equipment on one side of the forming wire designed to accept airborne absorbent material and evenly distribute the absorbent material in the forming wire. Normally located on the other side of the forming wire, working in conjunction with the equipment distributor, there is a vacuum system that is present to collect the absorbent material suspended in air on the forming wire. The present invention provides a reduction of the vacuum in specific areas in the y-direction, so that one or more of the base weight, density or SAP content of the absorbent material collected in the forming wire is profiled. In a preferred embodiment of the invention, the vacuum used to collect absorbent material suspended in air is blocked, essentially reducing the vacuum to zero in specific areas in the CD. When the vacuum is blocked in specific zones, the striped layers of the present invention can be formed. In another preferred embodiment of the invention, the distribution of absorbent material suspended in air is physically blocked in certain areas, in order to cause deposition in the forming wire, which is profiled in the transverse direction of the machine and can forming the striped layers of the present invention. This invention provides a process for the production of an absorbent structure comprising a plurality of layers, at least one stratum of which is produced by a series of unit operations and which contains functional particles and has a y-directional profile comprising first and second zones located in contact with one another, where the first The zone has one or more of a higher density, higher content of functional particles or basis weight greater than the second zone, the process comprising: (1) forming a first stratum A comprising fibers and, optionally, functional particles; (2a) forming a second stratum B comprising fibers and functional particles, such that a larger surface of B is in fluid communication contact with a larger surface area of A and the y-directional length of B is better than the longitude y-directional of A; or (2b) forming a second stratum B comprising fibers and functional particles, so that the first and second zones arranged in contact with each other are formed, wherein the first zone has a higher density and a greater content of functional particles than the second zone. In particular modalities of the process described above, the strata are formed in a wire forming an airborne process of fibers and functional particles distributed from a forming head and the first and second zones of stratum B are formed by partially blocking the distribution. in the second zone but not in the first zone. In an alternative embodiment of the process of the invention, strata are formed in a wire forming a process suspended in air from fi bres and functional particles distributed from a forming head and the first and segmented areas of stratum B are formed by partially blocking the distribution in the second zone but not in the first zone. The invention is also directed to absorbent structures made through the process described above.

Brief description of the djs Figs. 1 shows a unitary absorbent structure in a forming wire and shows the x-direction, the y-direction, and the z-direction in relation to the structure; Fig. 2a shows a unitary absorbent structure; Fig. 2b shows a unitary absorbent structure of the invention; Fig. 2c shows a unitary absorbent structure of the invention; Fig. 3 shows an absorbent structure of the invention having a structural and -directional profile of SAP content and density; Figs. 4a-4i show unitary absorbent structures of the invention with three layers, including striped layers; Figs. 5a-5d show additional embodiments of the absorbent or inventive structures of the invention; Fig. 6 shows an absorbent structure of the invention composed of two layers, wherein the upper layer has a structural and directional profile of density and content of SAP; Fig. 7 shows an absorbent structure of the invention composed of two strata, wherein the lower stratum has a structural and directional profile of density and content of SAP; Fig. 8 shows a process for making an absorbent structure according to the present invention; Fig. 9 shows an approximation of the forming wire of FIG. 8; Fig. 10 is a view along the direction A to B of the forming wire of Fig. 9, Figs. 1 1 A and 1 1 B show a tester used to test absorbency properties of absorbent structures of the present invention, Fig 12 shows a Gurley stiffness tester used to measure the flexibility of the absorbent structures of the invention, Figs. 1 3A and 1 3B show a clamp used to measure the flexibility of the absorbent structures of the invention, Figs. 14A-14C show base weight profiles of samples A to C, Fig. 5 shows directional weight profiles-y for samples A to C, Fig. 1 6 shows d-direction and density profiles. for samples A to C, FIGS. 1A and 7B show schematic drawings for samples D and E, FIGS. 18A and 1B show schematic drawings for samples F and G, and FIG. rewetting properties as a function of base weight and width d e lower layer for samples H and J DETAILED DESCRIPTION OF THE INVENTION All patents and patent applications cited in this specification are incorporated herein by reference in this specification In case of conflict in thermology, the present description has control.

Definitions As used herein, the term "stratum" and in the plural "strata" means the production of a unitary operation designed to place absorbent material on the forming surface, which can employ a carrier tissue, or a wire of a forming process. The process can be of suspension in humidity or suspension in air, but preferably it is of suspension in air. The materials deposited on the forming surface by the unit operation include fibers, powders including additives and functional particles, such as SAPs and binders. The totality of material deposited on the forming surface can be referred to as a "weft", which grows during the forming process as successive unit operations are added to the weft. As used herein, the term "profiled layer" means a stratum, in which one or more of the basis weight, density or content of functional particles (such as, super absorbent polymer particles) of the stratum varies (is profiling) in the y-direction and / or z-direction. As used herein, the term "striped layer" means a special case of a profiled layer in which one or more of the base weight, density or content of functional particles of absorbent material in the stratum fall to very low or zero levels. for a finite length in the y-direction. This finite length of basis weight, density or content of Zero functional particles can be continuous or can be divided into discontinuous segments. The divided segments can be distributed in a pattern in the y-direction or there may not be a uniform pattern. The finite length of very low or zero levels of basis weight, density or content of functional particles can be distributed symmetrically around the longitudinal axis of the structure or distributed asymmetrically around the longitudinal axis of the structure. As used herein, the term "sheet" refers to a fibrous material that can be used as a component in an absorbent article. A nonabsorbent absorbent core is an example of a sheet. Other example sheets include a storage and acquisition layer, a liquid-permeable top sheet and a liquid-impermeable backsheet. A series of sheets can be assembled in an absorbent article in a converting process, in which sheets are attached by glue or other adhesive, by thermal bonding or by pressing or densifying the sheets to produce matting. As used herein, the term "content" means percentage by weight. In this way, the content of functional particles in a given stratum is the percentage by weight of functional particles in that stratum. As used herein, the term "x-direction" refers to the direction along the length of the absorbent article 1, as illustrated in Figure 1. When the weft is formed so that the absorbent article is disposed in a horizontal or planar shaper 2, the x-direction is the machine direction (MD).

As used herein, the term "y-direction" refers to the direction along the width of the absorbent article (see Figure 1).

Referring to Figure 1, when the weft is formed, so that the fibrous material is arranged in a horizontal or planar forming wire 5, the y-direction is the machine's transverse direction (CD). As used herein, the term "z-direction" refers to the direction in the plane of the absorbent article (see Fig. 1). As used herein, the term "width" of a stratum is the distance from one side of the stratum to the other, measured in the direction-and normal to the longitudinal axis of the structure. As used herein, the term "basis weight" is the weight of a frame per unit area. It is usually expressed as grams per square meter (g / m2 or gsm). Base weight is an intensive property of a plot, since it is dependent on the amount of plot that is present. As used herein, the term "density" is expressed in grams per cubic centimeter (g / cc) and is defined according to the following equation: Density (g / cc) = basis weight (g / m2) / [ 1, 000 cm / m2 x thickness (cm)] As used herein, the term "unitary absorbent structure" or "absorbent structure" means a structure or core of the invention that contains one or more layers. When the unitary absorbent core contains a plurality of strata, there is no interphase between the strata, that is, once the strata are arranged with one another they can not be separated. The unitary absorbent structures, the which are formed from more than one stratum, they are formed without glue or other adhesive between the layers. A unitary structure can be formed, for example, in a single line of manufacture, for example, in a line suspended in simple air. Normally, the absorbent cores suspended in air contain a combination of cellulosic fibers, mixed with various functional synthetic fibers, functional or granular particles and additives.

Absorbent Structures The present invention includes an absorbent structure, which can be used as a core, having a base weight profile, density or SAP content in its direction-y, the direction perpendicular to the longitu- dinal axis of a product. finished In particular modalities, the structure can be outlined in both directions y and z. The absorbent cores of the prior art usually comprise strata that run the full width of the core. As shown in Figure 2a, in the existing technique, all strata are of the same width. The present invention can be used to improve the existing technique by providing a method for selectively placing absorbent material, where it can be used more efficiently. For example, as shown in Fig. 2b, the present invention contemplates the placement of absorbent material in a selective manner in the center of the absorbent core an itar, at the point of fluid attack, in place of Evenly move the absorbent material through the full width of the incillo pad. While 2b illustrates the use of strata having different widths, in fact the structure of the invention will appear as Figure 2c, in which the strata having greater width will find in the area where the stratum has smaller width is absent. The resulting structure is profiled in the directions y and z to form a zone containing higher basis weight, density or functional particle content. Analogous to placing absorbent material in a unitary absorbent core where it can be used more efficiently, the present invention contemplates the removal of unitary absorbent core material where it is not being used efficiently. Profile profiling can be used to reduce raw material costs by removing absorbent material from the unitary absorbent core where it is not effective. With reference to Figure 3, where the y-direction and the z-direction are indicated by arrows, the structure of the invention comprises at least one zone A, having one or more of greater basis weight, density or content of particles. functional (such as, SAP), and preferably at least two such areas A, having one or more of greater basis weight, density or content of functional particles (such as SAP), as well as at least one zone B having lower base weight, density or content of functional particles or without functional particles. In one of the preferred embodiments, the zones A have a higher basis weight than the zones B. one, and preferably two, of the zones A, can be located at the edges on the sides of the absorbent structure. For example, a y-directional and / or z-directional profile can be achieved by placing more SAP particles together with natural fibers or Synthetics in narrow fields creating zones A along the absorbent structure. Such zones are then separated by fields of lower density of natural or synthetic fibers with less SAP or without SAP, thus creating zones B. Such controlled placement of SAP particles allows for better containment of the particles within the structure. Absorbent and allows an easier and twisted flow of the fluid along the length of the core (x-direction). The flexibility of such a material can also be improved in this way, in particular through the width of the core. In addition, the structures of the invention may have an unexpectedly high velocity of fluid acquisition, this is an SAP content greater than 30 percent. The absorbent structures known hitherto could not achieve such high acquisition rates at high SAP content due to the drastic loss in permeability of these structures when they were saturated. This effect is associated with the so-called SAP gel block as the SAP particles swell and close the pores in the absorbent core. Without being bound by a theory, it is believed that the high acquisition rates of the structures of the invention, containing a high amount of SAP, are due to the capacity of these structures to maintain their high volume of vacuum and acquire more liquid. in areas B (having one or more of lower basis weight, density or SAP content) still at a high degree of saturation of the absorbent structure. It is also believed that the high hollow volume in zones B can be maintained because the liquid is removed from them by capillary forces to denser areas A, where it is retained by SAP particles in higher concentration. As a consequence of this, the structures of the invention have at the same time, an exceptionally high storage efficiency and fluid acquisition. This in turn allows improved performance of the finished absorbent product, for example, a personal hygiene product, by reducing leakage during its use and for better utilization of the absorbent core. An increased amount of SAP in the absorbent core also allows manufacturers to produce thinner, more absorbent and more comfortable absorbent articles. A measurement used to evaluate the absorptive properties of a structure is the fluid acquisition and storage efficiency ("PHASE"). PHASE is a dimensionless number, which is obtained by multiplying the speed of fluid acquisition and the content of SAP particles in an absorbent structure. The greater the speed of fluid acquisition and the greater the content of SAP particles, the greater the PHASE. However, until now, it has been difficult to achieve both high acquisition speed and high SAP particle content at the same time, because any increase in SAP particle content generally led to more gel blocking, less permeability and, consequently, a lower fluid acquisition speed. Desirably, the absorbent structures of this invention have a PHASE of 50 or more, more desirably 80 or greater, preferably 1 00 or greater and more preferably 1 80 or greater. Referring to Fig. 3, the speed of fluid acquisition can be further enhanced if the structure of the invention The invention relates to a porous upper stratum C without essentially having twisted properties x, y and capable of maintaining a substantial surface seq uence. Such a layer can be made, for example, with a matrix of synthetic fibers a bond with a binder. In some embodiments of the invention, the stratum C is a low density acquisition stratum including from 50 to 99 weight percent synthetic wettable fibers, preferably from 75 to 90 percent synthetic fibers, with the remainder of the stratum binder material. Because of its relatively low density, large pore size, and lower wettability than the other stratum below, stratum C has essentially no water-wicking capacity x, y. The fluid is easily twisted from it down to the more wettable stratum and smaller pore, higher density below. In the preferred case, the stratum C i would include synthetic fibers having a thickness from 2 to 35 dtex, preferably from 6 to 17 dtex. In this mode, the synthetic fibers have a length from 2 to 1 5 μm, preferably from 4 to 12 mm. Optionally, the fibers may curl and may have a variety of cross-sectional shapes. Examples of suitable synthetic matrix fibers include polyethylene, polypropylene, polyester, including polyester terephthalate (PET), polyamide, polyacetates, cellulose acetate and rayon fibers. Certain hydrophobic synthetic fibers, such as polyolefins, should be surface treated with surfactant to improve wettability. Preferred embodiments of the unit absorbent structures of the invention contain at least one striped layer. A striped layer is a stratum in which one or more of the basis weight, density or content of functional particles (such as SAP) falls to very low levels or zero for a finite length in the y-direction. This finite length of very low or zero levels of basis weight, density or content of functional particles can be continuous or can be divided into discontinuous segments. The divided segments can be distributed in a uniform pattern in the y-direction or they may not be in a uniform pattern. The finite length of very low or zero base weight levels can be distributed symmetrically around the longitudinal axis of the structure, or it can be distributed asymmetrically around the longitudinal axis of the structure. Figures 4a-4i show designs of three-layer, representative absorbent structures containing at least one striped layer. Figures 4c, 4e, 4f and 4g show absorbent structures with more than one striped layer. As shown by Figure 4g, the striped layers do not necessarily have the same width. As shown by Figure 4, the invention contemplates absorbent structures with more than one ray per stratum. As shown by Figure 4i, the invention also contemplates striped layers that are not centered with respect to the longitudinal axis of the structure. Figures 4a-i show the absorbent structures in a theoretical manner. In fact, as explained in the discussion of Figures 2b and 2c, strata that have greater width will be found in the area where the stratum or strata that have less width are absent.

Figures 5a-5d show still further embodiments of the absorbent structures of the present invention. Figures 5a-5d show how structures can be constructed stratum-by stratum. In fact, in the structures of Figs. 5a-5d, the strata that have greater width will be found in the area where the stratum or strata that have less width are absent. These additional modalities can be produced by vacuum segmentation, that is, by segmenting the vacuum system under the wire forming the suspension process in air. The vacuum system can be segmented into relatively high vacuum regions and relatively low vacuum regions. According to a method of the invention, the vacuum can be physically blocked in certain areas, in order to reach areas of one or more of higher basis weight, density or content of functional particles (such as SAP). In alternative methods of the invention, a block or mask can be used to protect the vacuum in the desired areas, in order to reach areas of no or more of higher basis weight, density or content of functional particles (such as SAP). In an additional method of the invention, the distribution of absorbent material bound with air is physically blocked in certain areas, in order to avoid deposition in the forming wire. In this way, a flow divider or other block can be disposed between the outlet of the particle forming or applicator head and the forming wire, to block the deposition of particles or fibers. This results in an absorbent structure, which is profiled in the y-direction.

Figure 5a is an example of an absorbent structure having more than one stratum, in which the lower stratum is formed by blocking the deposition of particles or fibers at the edges of the forming wire, or by segmenting the vacuum system in a relatively high vacuum region in the center of the forming wire and relatively low vacuum regions at the edges of the forming wire. In this way, regions of high basis weight are formed by relatively high vacuum and low base weight regions are formed by relatively low vacuum or by blocking the deposition of fibers or particles. Figure 5b shows a modality of the invention containing multiple regimens of relatively high base weight and relatively low in the y-direction. Figure 5c shows a modality of the invention in which the center of mass of the unitary absorbent structure need not correspond to the longitudinal axis. Figures 4 and 5 show examples of how the absorbent structures of the present invention can be constructed, stratum by stratum in a suspended line in normal air modified as described by the present invention. Once the strata have been formed, the present invention provides uniform compaction or densification of the absorbent material. The compaction may also provide unitary absorbent structures to be used as cores, having a density variation in the CD. The absorbent structure can also be used as cores in absorbent articles. In one embodiment of an absorbent article of the invention, shown in Figure 6, the structure of the invention comprises two Separate absorbent structures (or sheets), where structures are in fluid communication with others. The structure includes a shorter, upper structure 3, and a longer, lower absorbent structure 4. In general, the surface area of the lower surface of the upper structure 3 is less than 80 percent of the surface area of the structure. the lower surface of the lower structure 4. This arrangement has an advantage over the structures of a single stratum, by allowing a better containment and use of the absorbent material during the use of the absorbent article by the user. In Figure 6, the upper structure of this modality is an absorbent and shaped structure comprising the zones A and B (where the A zones have and no or more of greater weight basis, density or content of functional particles than the zones B), of the type exemplified in Fig. 3. In another embodiment of an absorbent article, shown in Fig. 7, the lower structure 5 of the two-frame system is a profiled absorbent structure of the invention that comprises zones A and B. The surface area of the lower surface of upper structure 6 is less than 80 percent of the surface area of the upper surface of the lower structure 5. Yet another example of the two-layer mode is a system, in which both the upper layer as the lower layer are y-shaped structures of the invention comprising zones A and B. With reference to Figure 6, the advantage obtained by providing a system of two structures as described above, is that the discharge of fluid from the human body occurs mainly on the frontal region 7 and the central region 8 of the absorbent core. This mode places more of the absorptive capacity in the region where the liquid discharge attacks the nucleus.

Fibers The structures of this invention may include natural fibers, synthetic fibers or mixtures of both natural and synthetic fibers. Examples of the natural fiber yarns, which may be used in the present invention, include fluffed cell fibers prepared from cotton, pulps of softwood and / or hardwood, straw, keaf fibers, cel uloses modified by chemical, mechanical and / or thermal treatments, keratin fibers, such as fibers obtained from feathers, bagasse, hemp and flax, as well as fibers made by man made from natural polymers, such as cellulose , chitin and ueratin. Cellulosic fibers include chemically modified cellulose, such as cellulose fibers that are substantially endued with crosslinking agents, fibers treated with mercerizing agents and cellulose acetate. Examples of suitable synthetic matrix fibers include polyethylene, polypropylene, polyester, including polyester terephthalate (PET), polyamide, polyacetates, cellulose acetate and rayon fibers. Certain hydrophobic synthetic fibers, such as polyolefins, should be surface treated with surfactant to improve wettability. The final purity of the preferred cellulose fiber of the present invention can vary from at least 80 alpha percent to 98 percent of alpha cellulose, although the purity of more than 95 percent is preferred and the purity of 96.5 percent of alpha cellulose is highly preferred. As used herein, the term "purity" is measured by the percentage of alpha cellous present. This is a conventional measurement in the industry to dissolve pulp. Methods for the production of cell fiber or slabs of various purities normally used in the paper and paper industry are known in the art. Preferred fibers used in zones having higher levels of basis weight, density or content of functional particles (such as Zones B in Figure 3) are those that have a lower water retention value (WRV). The water retention value (WRV) of ulic cel fibers is an indication of a capacity of the fiber to hold water under a given amount of pressure. The cellulose fibers that are soaked in water are moderately incubated, and physically retain water in the swollen areas of the fiber. When an aqueous fiber slurry is centrifuged, most of the water is removed from the fibers. However, an amount of water is retained by the fiber even after centrifugation and this amount of water is expressed as a percentage based on the dry weight of the fiber. Fibers having lower WRV value are, in general, more rigid than conventional fleece fibers and thus contribute to an improved structure permeability. The preferred water retention value (WRV) of the cellulosic fibers of the present invention is less than 85 percent, more preferably between 30 percent and 80 percent, most preferably 40 percent. The WRV refers to the amount of water calculated on a dry fiber basis, which remains absorbed by a sample of fibers that has been soaked and then centrifuged to remove water between the fibers. The amount of water that a fiber can absorb is dependent on its ability to swell at saturation. A smaller number indicates that internal cross-linking has taken place. U.S. Patent No. 5, 190, 563 discloses a method for measuring WRV. Preferred fibers used in areas having lower levels of basis weight, density or content of functional particles (such as zones B in Figure 3), are those that have a greater curl. The curl is defined as a fractional shortening of the fiber due to ulo, spin and / or mixtures in the fiber. The percent curl of the cellulose fibers of the present invention is preferably from 25 percent to 80 percent, and is more preferably from 40 percent to 75 percent. For the purpose of this description, the fiber curl can be measured in terms of a bi-dimensional field. The curl is defined as a fractional shortening of the fiber due to the curls, turns and / or blends in the fiber. The curl percentage of the cellulose fibers of the present invention is preferably 25 percent to 80 percent, more preferably 75 percent. For the purpose of the description, the fiber curl can be measured in terms of a two-dimensional field. The curl of the fiber is determined by observing the fiber in a two-dimensional plane, measuring the projected length of the fiber as the longest dimension of a rectangle that encompasses the fiber, L (rectangle), and the actual length of the fiber L (real), and then calculate the fiber curl factor from the following equation: Curl factor = L (real) / L (rectangle) - 1 A method of Fiber curl index image analysis is used to make this measurement and is described in U.S. Pat. 5,190,563. The curl of the fiber can be imparted by mercerized. Methods for the cellulose mercerization normally used in the pulp and paper industry are known in the art. Another source of cellulosic fibers for use in the present invention, especially for use in areas having lower basis weight, density or content of functional particles (zones B), is that of chemically hardened cellulose fibers. As used herein, the term "chemically hardened cellulose fibers" means cell fibers that have been treated to increase the stiffness of the fibers under both wet and dry aqueous conditions. In the most referred hardened fibers, chemical processing includes intrafiber crosslinking with crosslinking agents, while such fibers are in a relatively dehydrated, defibrated (ie, individualized), twisted and crimped condition. It is reported that these fibers have ripple values greater than 70 percent and WRV values less than 60 percent. Fibers hardened by crosslink bonds in an individualized manner are described, for example, in U.S. Pat. 5,217,445 issued June 8, 1993, and US Patent No. 3,224,946 issued December 21, 1965.

Another source of cellulosic fibers for use in the present invention, especially for use in areas having lower basis weight, density or content of functional particles, are fibers obtained from high-yield pulp, which is cellulose pulp containing lignin. Normal examples of such fibers are chemical thermo-mechanical pulp (CTMP) or bleached thermo-mechanical chemical pulp (BCTM). These fibers are stiffer in both dry and wet state, than cellulose fibers with a low content of or without lignin.

Functional Particles The functional particles for use in the absorbent cores of the invention include particles, flakes, powders, granules or similar, which serve as absorbers, odor control agents, for example, zeolites or calcium carbonates, fragrances. , detergents, antimicrobial and similar agents. The particles can include any functional powder or other particle having a particle diameter of up to 3,000 μ (m). In preferred embodiments, the particles are particles of superabsorbent polymers ("SAP"). US Patents Nos. 5, 147, 343; 5, 378, 528; 5, 795,439; 5, 807, 916; and 5, 849, 21 1, which describe various superabsorbent polymers and methods of manufacture, are incorporated herein by reference. Examples of the types of SAP particles that can be used in this invention include superabsorbent polymers in their particulate form, such as irregular granules, spherical particles, strand fibers and other particles. lengthened The term "superabsorbent polymer" or "SAP" refers to a polymer that is normally soluble in water, which has been cross-linked. There are known methods for making water-soluble polymers, such as carboxylic polyelectrolytes to create hydrogel-forming materials, now commonly referred to as superabsorbents or SAPs, and it is well known to use such materials to enhance the absorbency of disposable absorbent articles. There are also known methods of polyelectrolyte crosslinking carboxylates to obtain superabsorbent polymers. SAP particles useful in the practice of this invention are commercially available from a number of manufacturers, including Dow Chemical (Midland, Michigan), Stockhausen (Greensboro, North Carolina) and Chemdal (Arlington Heights, Illinois). A conventional granular superabsorbent polymer is based on polyacrylic acid, which has been cross-linked during the polymerization of any of a variety of multi-funconal co-monomer crosslinking agents, as is well known in the art. Examples of multifunctional crosslinking agents are set forth in US Pat. Nos. 2,929,154; 3,224,986; 3,332,909; and 4,076,673. Other water-soluble polyelectrolyte polymers are known to be useful for the preparation of superabsorbents by cross-linking, these polymers include carboxymethyl starch, carboxymethyl cellulose, chitosan salts, gleatin salts, etc. However, they are not commonly used on a commercial scale to intensify the absorbency of disposable absorbent articles, mainly because of their lower absorbing efficiency or higher cost.

The superabsorbent polymers are well known and commercially available. The superabsorbent particulate polymers are also described in detail in U.S. Patents 4,102,340 and Re 32,649. Suitable SAPs produce high gel volumes and high gel strength as measured by the hydrogel cutting module. Such preferred SAPs contain relatively low levels of polymeric materials that can be extracted by contact with synthetic urine (so-called "extraibles"). SAPs are well known and commercially available from various sources. An example is a starch graft polyacrylate hydrogel marketed under the trade name IM1000 (Hoechst-Celanese; Portsmouth, VA). Other commercially available superabsorbers are marketed under the trademark SANWET (Sanyo Kasei Kogyo, Kabushiki, Japan), SUMIKA GEL (Sumitomo Kagaku Kabushiki, Haishi, Japan), FAVOR (Stockhausen, Garyville, LA) and the ASAP series (Chemdal; Aberdeen, MS). The polyacrylate-based SAPs are very preferred for use with the present invention. As used in the present invention, SAP particles of any size or shape suitable for use in the absorbent core can be employed.

Binders If the use of binders is preferred, examples of binders useful in the absorbent structure of the present invention include polymeric binders in a solid or liquid form. The term "polymeric binder" it refers to any com- ponent capable of creating interfiber fibers between matrixes to increase the integrity of the stratum. At the same time, the binder can optionally join fibers and SAP particles with one another. For example, a dispersion of natural or synthetic elastomeric latex can be used as a binder. The thermoplastic fibers or powders, which are well known in the art, are also commonly used to provide the binding on heating of the absorbent structure to the melting point of the thermoplastic fiber or powder. Other binders, which can be used to stabilize the absorbent structure of the present invention, include binding agents used to bind cellulose fibers. These agents include polymers dispersed in water, which are cured after application to the fibrous web and create bonds between fibers or between fibers and SAP particles. Examples of such agents include various ionic cation starch derivatives and synthetic cationic polymers containing crosslinkable functional groups, such as polyamide-polyamine epichlorohydrin adducts, cationic starch, dialdehyde starch and the like. Any combination of the polymeric binders described above can be used to stabilize the structure of the present invention. Suitable binders for use in the structures of the invention include binders in liquid form or having a liquid carrier, including latex binders. Useful latex binders include copolymers of vinyl acetate and acrylic ester, copolymers of ethylene vinyl acetate, copolymers of styrene butadiene carboxylate, and polyacrylonitriles, and see them, for example, under the trade names of Airbond, Airflex and Vinac of Air Products, I nc. , Hycar and Geon from Goodrich Chemical Co., and Fulatex from H. B. Fuller Company. Alternatively, the binder may be a non-latex binder, such as binding agents applied in aqueous solutions (eg, cymene, dialdehyde starch, qitosan or PVA) or epichlorohydrin and the like. To bond the fibers in a specific manner, and for a structural integrity of the generally unitary absorbent structure, latex binders based on water can be used. Alternatively, or in combination with a latex ligation, thermoplastic bonding material (fibers or powders) can be used. Such thermoplastic bonding material includes thermoplastic fibers, such as bicom thermoplastic fibers ("bico"). Preferred thermoplastic bonding fibers provide enhanced adhesion for a wide range of materials, including synthetic and natural fibers, synthetic and natural carrier particles and sheets. An exemplary thermoplastic bico fiber is Celbond type 255 Bico fiber from Hoechst Celanese. Other suitable thermoplastic fibers include polypropylenes, polyesters, nylons and other olefins, or modi? Cations of the same. A preferred thermoplastic fiber is FiberVisions type AL-Adhesion-C Bicomponent fiber, which contains a polypropylene core and an activated copolyolefin sheath. In certain embodiments, the binder in the invention is a binding fiber, which comprises less than about 10 percent by weight of the SAP particles. In other embodiments of the invention, the Binder fibers comprise less than about 7 weight percent of the absorbent structure.

Manufacture suspended in a structure of the invention An absorbent structure having improved particle containment can be delivered in the form of rolled products, or in other packaging formats, such as scallops, and is particularly useful as an absorbent core. for disposable absorbent articles, such as diapers, incontinence pads for adults, and very short underpants and feminine sanitary napkins. Preferably, the structure of the present invention is prepared as a suspended frame in air. The air suspended pattern is normally prepared by disintegrating or defibrating a leaf or sheets of slab cellophane pulp, usually by means of a hammer mill, to provide individualized fibers. • The individualized fibers are optionally mixed with functional particles, and then are transported with air to one or more forming heads in the air-suspended weft-forming machine. The forming head then deposits a layer in the forming wire. A stratum may contain, for example, Decal slab fibers, SAP and other functional particles, and bicomponent fibers.; In some embodiments, the structures of the invention contain a carrier tissue. The use of a com pacting roller before the introduction of the particle areas im im the need for the tissue.

Through the use of flow dividers or vacuum blocks, each of the forming heads is adapted to provide a stratum having zones of one or more of higher basis weight, density or content of functional particles, for example, SAP. Unit operations involve the use of multiple forming heads, for example, up to four, five, six or seven forming heads can be used to provide additional layers to the screen. Any one or more of the strata may comprise zones of one or more of higher basis weight, density or content of functional particles, for example SAP. According to the method of the invention, the zones can be obtained by physical blocking with a mask, preventing the absorbent material from being deposited in specific areas, by summarizing it in an absorbent product with profiled layers. Alternatively, the zones can be obtained by vacuum segmentation, controlling the vacuum properties, after depositing the stratum of the forming head. Vacuum segmentation can be used to control the width of the stratum. For example, vacuum segmentation can be achieved through the use of a training screen. Several manufacturers make airborne weave forming machines, including M &J Fibretech from Denmark and Dan-Web, also from Denmark. The forming heads include rotating drums, agitators generally in a stroke configuration, which serve to maintain fiber separation until the fibers are pulled by vacuum onto a foaming solid drum or foraminous forming conveyor, or forming wire. For example, in machines manufactured by M &J Fi bretech, the forming head includes a rotary shaker on top of a screen Other fibers, such as a synthetic thermoplastic fiber, can also be introduced to the forming head through a fiber dosing system, which includes an opener of fiber, a unit of dosage and an air tranposrtador The weft suspended in air is transferred from the forming rod to a calender or another stage of densification to densify the weft, increase its strength and control the thickness of the weft The fibers of the The weft can, alternatively or additionally, be joined by application of a binder or foam addition system, followed by drying or curing. As a result, heat is formed between the thermoplastic material and the fibers of the various layers. is rolled then for future use Figure 8 shows a process for making a fibrous web according to the present invention Optionally, a carrier tissue 20 can be unwound from the supply roller 21 The tissue 20 is wound onto the forming wire 1 8 The tissue can alternatively be used as a carrier or as the lower layer of the absorbent structure As contemplated by the present invention, a forming head 24 of the weft-forming machine suspended in air distributes the desired fiber to form the lower layer 23 of the absorbent structure. The layers can comprise additional fibers, such as cellulosic fiber, thermoplastic fibers and functional particles.

As contemplated by the present invention, no or more forming heads of the air-suspended weft forming machine distribute the desired fiber for the various strata of the core or absorbent structure. For example, a first forming head can be used to provide a first fibrous layer, for example, a layer comprising a cell fiber, bicomponent fiber and optionally a carrier tissue. The first stratum can be a twisted stratum. The functional particles can be applied optionally (or additionally) to the lower layer by means of the particle applicator 28. In this way, the SAP particles or other functional particles are thus applied to the stratum 23 deposited by the forming head. 24. The deposition of fibers and particles in each stratum is controlled in order to create zones of one or more of greater base weight, density or content of functional particles. As further described in Fig. 9, the forming wire 40 has flow dividers above or blocks 41, which are disposed on the forming wire and below the outlet of the forming head. For example, the flow dividers 41 can go to a car or other device, which is located above the forming wire. The fibers or particles that are deposited from the forming head are blocked from the forming wire. As a result, the stratum contains zones of one or more of greater basis weight, density or content of functional particles. Areas can be varied by manipulating the location or size of the dividers of flow or by variation of the types and quantities of fibers and functional particles in each stratum. FIG. 10 shows the flow dividers 41 located above the forming wire 40, along the direction A? B of Fig. 9. In preferred embodiments, the flow dividers are tapered, so that the fibers or particles do not accumulate at the top of the divider. Also shown in Figure 1 are vacuum locks 42, which may be located lower than the forming wire in order to block the vacuum. Returning to Figure 8, optionally, the strata are compacted or densified in a pinch formed by a pair of rolls of calender 26. The fibers can be compressed to the desired thickness and density. The lower layer 23 can be compacted at this point in the manufacturing process to close the pores of the weft if the particles are fine, and to prevent spillage on the forming wire. The additional stages 27 and 28 can then be formed in the upper part of the lower layer 23 in the same manner that the first layer is formed, by the use of forming heads 30 and 31, optionally particle applicators 33 and 34, and optionally pinching formed by rolil the calandria at 35 and 36. The web suspended in air is transferred from the forming wire 18 and is compacted or densified, for example, by the use of a calender 37 or to increase its strength and control screen thickness. The preferred densification ranges are from about 0.035 to about 0.50 g / cc, more preferably about 0. 050 to about 0.50 g / cc, even more preferably about 0.20 g / cc. The web is then subjected to additional treatment including pressure, heat and / or the application of a binder. For example, a binder (such as an atomizer or foam binder) can be applied to fatliquoring agents, which can be disposed after the calender 37. A series of furnaces can also be used in processes of the invention. , after the application of the logante, for drying, curing or thermal bonding. The structure suspended in air can be heated to a temperature in the range from 1 25 to 1 80 ° C. An additional global ligand can then be applied to the structure. This binder can be applied by atomization, foam or nybla, and is applied to reduce dusting on the surface of the structure. The structure suspended in air can be heated in additional furnaces at a temperature in the range from 1 25 to 1 80 ° C. The structure suspended in air can be treated at a pressure in the range of 0.7 kPa to 70 kPa, preferably 1 0 kPa. The finished frame is then rolled into the rod 50 for future use. This web of fibrous web can be split or cut to form individual absorbent articles in a cutting unit, which has not been shown in this figure. Optionally, the finished weft can be split or punctured in the sel with heat to produce narrow split core material having a heat seal along both edges. Seals with heat to be split must be of sufficient width to provide two effective seals after the match.

In other embodiments, various other strata containing other types and amounts of fibers may be applied above or below the upper and lower strata of the structure of the present invention. For example, the absorbent article may also contain a fluid-permeable topsheet and a fluid-impermeable backsheet. Exemplary absorbent articles that can be formed from the absorbent cores of the invention include diapers, sanitary napkins and incontinence products for aditus.

Test methods 1. Time and speed of acquisition of fluid The time of acquisition, the time for a given volume of saline to be absorbed by an absorbing structure (until any free liquid disappears from the surface of the absorber), was measured. . The following method was used to measure the time of acquisition: 1. Condition the sample in the laboratory at 21 ° C and 50 percent relative humidity for 2 hours before the test. 2. Prepare standard saline solution (0.9 percent NaCl in deionized water by weight). Add dye if desired. 3. Determine the attack volume and load to be used. Medium-capacity samples (most mid-sized diapers (size # 3)) use 3 x 75 ml of attack and 2.7 kPa of charge. 4. If the sample is formed in the laboratory or in a pi lotus machine (air suspension), cut to 1 0 cm x 35.6 cm for samples made in the first laboratory cushion, 10 cm x 40.6 cm for samples made in the pilot machine. If the sample is a commercial cloth, simply cut the elastic bands of the shoes, so that the diaper is flat. Take weight / thickness measurements of each sample. 5. Prepare samples suspended in air by placing on a plastic backing sheet, Exxon EM B-685 polyethylene film, and add cover material, 1 5 g / m2 of Avgol bonded polypropylene. Ensure that the edges of plastic backsheet material bend toward the top of the sample to protect against leakage while testing. 6. Place the sample in the acquisition unit when placing the sample on the lower plate, position a piece of foam on top of the sample, place an attack ring in the hole in the foam and then position heavy top plates on the piece of foam. 7. Set the counter for 20 minutes and place it on the side of the test device. 8. With the stopwatch in one hand and the graduated cylinder containing the attack volume in another hand, prepare to attack the sample. Empty the fluid in the anchor ring. Ignite the stopwatch at the moment when the fluid hits the sample. Empty the cylinder fluid as quickly as possible. Stop the chronometer when the fluid is absorbed by the sample. 9. Record the time taken by the sample to absorb the fluid. Start the 20 minute counter as soon as the fluid is absorbed by the sample. 1 0. After 20 minutes, repeat steps 7-9. eleven . After another 20 minutes, repeat steps 7-9. Note: if no further tests are to be made after the acquisition test, the 20 minute interval following the third attack can be omitted. However, if another test is to be done following the acquisition test (rewet and retention or distribution), the 20 minute interval should be used and then another test can be started. The following formula is used to calculate the speed of acquisition: Acquisition speed (ml / s) = attack volume (m l) Acquisition time (s) 2. Rehumination and retention The rewet and retention test is designed to be performed immediately after the acquisition test. The procedure of the acquisition test must be followed before starting this test. If acquisition information is not needed, acquisition times do not have to be recorded, however the pattern of 3 attacks separated by 20 minute intervals should be followed. It is imperative that the interval of 20 m before the start of this test has elapsed. The sample / solution preparation is the same as in the fluid acquisition test. 1 . It is now assumed that the le has passed through the acquisition test and is left unchanged during the final 20 minute interval. Set a counter for 5 minutes and place to one side of the test apparatus. 2. Weigh a stack of 1 0 Buckeye S-22 blotters cut to the size as the le. 3. Remove the weight of the le, piece of foam and attack ring. 4. Place the stack of papers on the le. 5. Replace the piece of foam and weights on the le. I initiate the 5 m inutes counter. 6. At the end of 5 minutes, remove the weight and stack of papers. Record weight differences between wet and dry papers.

The rewet is calculated according to the formula: Rewet (g) = weight of wet papers (g) - weight of dry papers (g) The following formula is used to calculate the rewet retention after the third attack: % rehum hold, = vol. of all attacks (ml) - (rewet (q) x 1 ml / g) x 100 Volume of all attacks (ml) 3. Efficiency of storage and acquisition of fluid The efficiency of storage and acquisition of fluid, PHASE, is understood in the present, as a property of a structure absorber that combines its fluid acquisition performance with its fluid storage function, the latter being determined by the content of SAP particles. The storage and fluid acquisition efficiency is defined herein by the following formula: FAS E = (third acquisition speed, ml / s) x (SAP percentage) where the third acquisition speed is the acquisition speed of the third measured attack according to the method described in the section "Measurement of time and speed of acquisition of fluid" and percentage of SAP is the content in weight percent of SAP particles in an absorbent structure or in an acquisition component of a absorbent structure. The fluid acquisition efficiency is presented as a dimensionless number even though it is the product of the multiplication of the acquisition speed expressed in milliliters per second and of the content of SAP expressed in percent by weight. According to this definition, a structure exhibiting a high fluid acquisition velocity but not containing SAP particles will have a fluid acquisition and storage efficiency equal to zero. The structures of this invention have PHASE greater than 80, preferably greater than 120 and most preferably greater than 160. 4. Absorbent capacity This method is used to test diaper and incontinence structures for adustus that usually consist of an absorbent core containing superabsorbent polymer (SAP). All les should be conditioned at 21 ° C and 50 percent relative humidity before testing. This test is used to evaluate an absorbent structure capacity to absorb and retain fluid after being submerged in a saline reservoir. It is carried out under load in order to simulate the actual use of the product. From a performance point of view, it is important that a structure is capable of absorbing as much fluid as possible. Even more importantly, the structure should be able to retain the fluid. Otherwise, the user will have a wet sensation and the product may leak. Absorbency and retention capacity are reported both in units of grams per g branch. The following procedure is used to measure the absorbent capacity: A. For les of finished, commercial products: 1. Remove the folds of the legs, waist bands, etc., before cutting. 2. Measure the length of the nucleus to be evaluated. 3. If the length of the core is < 35.6 cm, for example, all newborn diapers, use the test apparatus of 1 0 cm x 35.6 cm. 4. If the core length is > 35.6 cm, use the test apparatus of 1 0 cm x 40.6 cm. 5. Most of the time, the core can not be cut to measure exactly 35.6 cm or 40.6 in length. When this is the case, it is necessary to "form" the smallest length to ensure that the load desired is applied to the core. Therefore, cut one section out of another core in order to make the total sample length either 35.6 cm or 40.6 cm. (This piece should be 10 cm wide and taken either from the front or back section of the core.) Wrap this section of the diaper in plastic in order to prevent any attack fluid from being twisted or absorbed on it. Some incontinence products for adults are larger than 40.6 cm. If this is the case, do not cut the product, instead, fold to form a 10 cm x 40.6 cm sample. 6. Determine the weight and thickness of the sample only. (Register as "dry weight"). Before weighing the sample, remove the back sheet and cover. It is usually difficult to remove the cover without tearing it to pieces. However, it is important to remove the cover as best as possible. Instead of getting the actual weight of the cover, assume that it weighs 18 grams and subtract this amount from the weight of the sample.

B. For previous samples of cushion or machine (pilot or plant): 1. Using a cutting board, cut samples to the required dimensions: 10 cm x 35.6 cm for samples made in the first cushion or 10 cm x 40.6 cm for samples made in either pilot or plant lines. 2. Determine the weight and thickness of the sample. (Register as "dry weight"). For all samples: 3. Condition the sample in the laboratory at 21 ° C and 50 percent relative humidity for 2 hours before the test. The samples that have already been tested do not need additional conditioning time, since they were already tested in a conditioned laboratory space. 4. Prepare 0.9 percent saline solution. For better visibility, add food grade dye, if desired. 5. Determine what load (via weight plates) will be used for evaluation. Choose the load depending on the type of the finished product, for example, for diapers of small size - 0.7 kPa (low capacity); diapers of medium size - 2.7 kPa (medium capacity); high capacity, adult incontinence products - 2.7 kPa or 6.8 kPa (large capacity). 6. Place the sample on the absorber tester screen (Fig. 1 1 A) Place the foam on top of the sample, followed by the required number of weight plates. For commercial cores, the cover sheet should be in contact with the screen, while the back sheet should face up. The same applies to the first-cushion and machine-made cores: the side of the sample that will be closest to the user should move to the screen while the bottom of the core should face up. 7. Set the counter for 20 minutes. 8. Open the valve to allow the fluid (0.9 percent NaCl solution, by weight, in deionized water) to flow from the zero-head vacuum bottle. This will help keep the fluid level constant. 9. Start the counter as soon as the sample is submerged in the saline container. 1 0. At least 2 minutes before the 20-minute period expires, close the vacuum valve and open the air ejector pump valve in order to allow a vacuum to draw fluid from the base of the screen. Also, open the water tap in order to provide maximum vacuum. All the liquid does not need to be removed; however, there should be no fluid in the display of apparatus B (Fig. 1 1 B). eleven . When the appropriate time has elapsed, close the water tap. 1 2. Remove the basket containing the sample and weight plates from the container and drain on a flat plastic board that has been covered with blotting paper. 1 3. Drain for 5 minutes. 14. Remove the plates of weight, foam and weigh the wet sample. Record the weight as "post-drainage wet weight". 1 5. Place a sheet of blotting paper on a flat surface.

Place the sample on top of the blotter. Add foam and weight plates. 16. Allow the sample to settle for 5 minutes. 1 7. Weigh the sample only. Record the step as "wet weight post blotter". The following formula is used to calculate the absorbent capacity: Absorbent capacity (g) = wet weight post blotter paper (g) - dry weight (g) The apparatus used to measure absorbency and retention is shown in Figures 1 1 A and 1 1 B. The absorbency tester consists of two parts. Part A (Figure 11A) is a container for holding the saline solution. A drain nozzle, which is located at the bottom of the container, should be approximately 2.5 cm long and approximately 1 cm in diameter. A support cylinder with 1 cm of opening is used to support the drain nozzle. Part B (Figure 11 B) has a thin screen (eg 200 mesh screen bed (nominal 0.07 mm screen opening and 0.05 mm internal wire diameter)). The screen is designed to hold a step of up to 11.35 kg. The sample and weight plates are placed at the top of this screen. Part B is placed inside part A. The foam is used during the test to place between the absorbent core and the weight plates. This foam is covered with plastic film (at least 4 mm thick) and sealed in any appropriate way (heat seal, seal tape, etc.), so that a waterproof barrier is created around the foam . 5. Wet Integrity As used herein, "integrity" is a measure of the tensile strength of a fibrous sheet, normalized to the basis weight unit and is expressed in units (milliNewtons, mN) of x-directional force required for break a sample 2.5 cm wide from the leaf by standard basis weight of 1 gsm. In order to measure the wet integrity (wet tensile strength) of an absorbent core or a commercial absorbent product, the following procedure is used: 1 . Samples of 2.5 cm x 1 0 cm are prepared. 2. Remove any back sheet, cover or removable plastic synthetic acquisition material, leaving only the core. 3. Weigh the sample. Apply 0.9 percent saline, in an amount equal to twice the weight of the sample, to the center of the sample using a pipette or spray bottle (Example: the sample weighs 1.00g, apply 2.00 g of saline solution for a total of 3.00 g). 4. Insert the sample into a voltage tester (eg, a universal Thwing-Albert LT-150 material tester, omission commando program settings used for testing) when placing in pressurized clamps. 5. Start the pureba. 6. When the test is completed, record the results displayed. These results include Strength in the peak, Lengthening in the peak, Maximum lengthening, Peak energy and Energy in the maximum. The wet integrity as used herein is defined as the peak force as measured by using the above procedure. The wet integrity of the absorbent structures of the present invention is greater than 4.0 mN / g / m2, and preferably greater than 6.0 mN / g / m2. 6. Softness The softness of the absorbent structure is an important factor that contributes to the overall conformability of the structure. As used herein, "softness" is the inverse of the amount of energy needed to compress a sheet, in this case, the sheet being the absorbent structure. The greater the amount of energy needed to compress a leaf, the less soft it is. To measure the softness of the core, the following procedure is used (a modified compression test): 1. Prepare the samples by cutting three pieces of 10 cm x 20 cm (if the sample is a diaper, cut from the thickest section of the diaper (if the thickness is not uniform)). For samples with obvious machine direction and cross direction, cut a dimension of 20 cm in the machine direction. 2. Allow the back sheet of plastic and cover material to remain in the sample (applies to samples of commercial diapers). If prototype core samples are tested, apply the plastic backing sheet, Exxon EMB-685 polyethylene film, to the bottom of the sample and cover, 15 gsm of Avgol spunbond polypropylene, to the top of the sample ( Same size as the sample, adhered with a small amount of spray adhesive). 3. Program the modified compression primer (for example, a universal material tester Thwing-Albert LT-150): The compression test using the following non-default settings: break detection method =% drop / displacement, value of break = drop% = 50, distance traps = 0.8 cm / 1.3cm / 1.8 cm, units: distance / displacement = cm; force = grams, test speed = 2.5 cm / min. All other settings are left by default. 4. Insert a sample into the tension tester using the customary clamps as shown in Figure 12. The clamp can be made of 0.16 cm thick aluminum and is 2.5 cm wide x 20 cm long. The U-shape simulates the way a diaper will take when placed on a baby. The function of the clamp is double. First, it facilitates the testing of a full-width kernel. Second, it maintains the U shape during the softness test, simulating the force required by the baby to compress the diaper between her legs, thus forming the diaper to her body. The sample is inserted in its edge, so that it will be compressed in the y-direction (10 cm direction), having 2.5 cm of both edges inside the customary clamps, thus leaving an opening of 5 cm. 5. Start the test. 6. When the deviation exceeds 1.8 cm, push down on the upper pressurized clamp to simulate a rupture of the sample and stop the test (it does not affect the results of the test). Record the results displayed. These results include peak force, peak deviation, maximum deviation, peak energy and maximum deviation energy and out of distance traps. The value, which is used to calculate the softness, is energy in maximum deviation, which is expressed in Joules. Maximum deviation energy, Ed max, is calculated according to the following formula: d max Ed max = 5 F dd cf min where Ed max is energy in maximum deviation, F is force in given deviation, d, and d min and d max are the deviations at the beginning of the test and at the end of the test, respectively. The softness, S, is defined here according to the following formula: S = 1 / (Energy in maximum deviation) The result, S, is expressed here in 1 by Joul, 1 / J. In general, the softness of the overall absorbent structure of the present invention should be greater than 8.0 / J, preferably greater than 15.0 / J. 7. Flexibility The flexibility of the absorbent structure is also an important factor that contributes to the overall conformability of the test. As used herein, "flexibility" is the inverse of the amount of force necessary to mix a sheet, in this case the sheet being the absorbent structure of the invention. The greater the force needed to bend the blade, the less felxible the blade is. The flexibility can be measured by the following procedure, using a Gurley tester (model 4171, Gurley Precision Instruments, Trey, NY). A sample Gurley stiffness tester is shown in Figure 12. 1. Cut the sample to 2.5 cm x 8.3 cm as precisely as possible. If there is a defined machine direction and cross direction, cut a sample in each direction and test each one. 2. Adjust the custom clamp as shown in Fig. 1 2, over the original clamp provided with the Gurley tester and tighten the smaller, upper thumbscrews to secure (see Figure 1 2, which illustrates the customary clamp raised sheets of higher basis weight). The customary clamp was designed in such a way that the thickness of the tested material does not change, where the material is inserted into the clamp. If the thickness is changed as a result of the clamps, then the properties of the structure change and the results obtained when using the Gurley tester are affected. In the present method, the clamp of Fig. 1 2 is used to eliminate such undesired effects. 3. The purpose for this customary clamp is to allow the testing of samples that are too thick to be tested using the existing Gurley clamp without being primed. The existing Gurley clamp allows the testing of samples that have a maximum thickness of approximately 0.63 cm. Examples of structures tested using the customary clamp are commercial diapers and prototype and diaper cores, and incontinence structures for adult commercial and prototype. This customary clamp allows the sample to be tested without any z-directional structural compression, such as would be present if the existing clamps were used. Therefore, this removes the densification during the test emission, which can have a significant adverse effect on the results of the test. 4. Open the adjustable clamp plate used when loosening the longer, lower wing screws. Place the sample in the clamp by sliding the sample until the original clamp is contacted. There should be 5 cm of sample contained in the customary clamp. 5. Adjust the height of the customary clamp by loosening the height adjustment screw on the original clamp. Adjust the height so that an opening of 2.5 cm exists between the point where the sample will contact the lever arm. 6. Make sure that the remaining 0.6 cm of the sample extends below the upper arm of the lever. Make sure that the arm of the lever is not moving. Press the motor button to move the sample towards the lever arm. Continue pressing the motor button until the sample releases the lever arm. While this is being done, observe and note the highest number reached on the scale. Repeat this in the opposite direction. 7. Average the two values obtained. In the conversion diagram of the apparatus, find the factor for a sample of 2.5 cm wide x 3.8 cm long, depending on the weight used and the distance the step was placed from the center on the lever arm. A 2.5 cm x 8.3 cm sample tested using the customary clamp corresponds to a 2.5 cm x 8.3 cm sample tested without using the customary clamp. Without the usual clamp, 0.6 cm of the sample is in the original clamp, 0.6 cm extends below the upper arm of the lever arm and 2.5 cm is the opening between them. Using the customary clamp, the same 0.6 cm is used in the customary clamp; the other 4.4 cm in the customary clamp ensure the thickest sample instead. The same 0.6 cm extend below the upper arm of the lever arm and the same 2.5 cm opening is between them. 8. Multiply the average reading on the scale by the appropriate factor of change found in the diagram. The result is the rigidity, which is expressed in m i l igramos force, mg. The flexibility, P, is defined here according to the following formula: P 1 06 / 9.81 * Rigidity. The result, P, is expressed here in 1 per Newton, 1 / N. In general, the flexibility of the complete absorbent structure of the present invention is greater than 60 / N, preferably greater than 80 / N. In the present invention, high levels of softness, flexibility and wetness can be achieved by applying one or a combination of the following characteristics in the preparation of an absorbent structure: by using soft fibers, crimped or curled fibers, applying mild binding systems, such as, for example, fine or curled bonding fibers, elastic latex binders or water binding solvents, by minimizing the amounts of binder, applying relatively low pressure during compaction before curing , and use relatively low pressure during calendering of the sheet after it has been cured. In general, the density of the sheet after compaction and / or calendering in the absorbent structures of the invention should be less than 0.35 g / cc, and preferably less than 0.3 g / cc. 8. Thickness The thickness is measured using a gauge of analogous thickness (B.C.

Ames Co .; Waltham, MA). The gauge has a foot of 4.1 cm in diameter and is equipped with a weight of 150 grams, so that the pressure applied to the sample is 11.4 g / cm2. The thickness is measured in inches and is converted to centimeters as needed for calculations. 9. Acquisition and rewet combination test The equipment involved in this test includes the following materials: Electronic balance (± 0.01 g precision) Fluid capture tester (FIT, Buckeye design "B144-97") S22 grade blotter, 10.16 cm x 24.13 cm Weight, 8408.5 g, 10.16 cm x 24.13 cm Latex foam, 10.16 cm x 24.13 cm x 3.81 cm Synthetic menstrual fluid Top sheet, polypropylene bonded by spinning, 22 g / m2, 25.4 cm x 10.16 cm Latex foam can be obtained from Scott Fabrics; Memphis, TN. Blotting paper can be obtained from Buckeye Technologies; Memphis, TN. The top sheet material can be obtained from Avgol Nonwoven Industries; Holon, Israel. The Buckeye design fluid collection tester (FIT) consists of a top plate and a bottom plate. The top plate is a plate of 29.7 cm x 19.0 cm x 1.3 cm of polycarbonate plastic. The plate has a hole cut off from its center and a cylinder Hollow pickup is mounted in the hole. The internal diameter of the collection cylinder is 2.5 cm and the complete upper plate weighs 872 grams. The bottom plate of the FIT is essentially a monolithic plate of 29.7 cm x 19.0 cm x 1.3 cm of polycarbonate plastic. The synthetic menstrual fluid used in the rewet acquisition combination test contains the following ingredients in the designated amounts: Deionized water 903.3 g Sodium chloride 9.0 g Polyvinylpyrrolidone 122.0 g Biebrich scarlet 4.0 g Total solution volume 1 liter Biebrich scarlet ( red dye) can be obtained from Sigma Chemical Co .; St. Louis, MO. The polyvinylpyrrolidone (PVP, weight average molecular weight of about 55,000) can be obtained from Aldrich; Milwaukee, Wl. Sodium chloride (ACS grade) can be obtained from J.T. Baker; Phillipsburg, NJ. The dry ingredients are mixed in water for at least two hours to ensure complete dissolution. The solution temperature is adjusted to exactly 22 ° C. 26 ml of solution are pipetted into the UL adapter chamber of a Brookfield viscometer model DV-II + (Brookfield Engineering Laboratories, Inc., Stoughton, MA). The UL spindle is placed in the chamber and the viscometer viscosity is adjusted to 30 rpm. The target viscosity is between 9 and 10 centipoise (32 and 36 kg / m hour). The viscosity can be adjusted with additional water or PVP.

The sample is cut to 7 cm x 20 cm with the longest dimension in the direction of the machine. The weight and thickness of the sample are measured and recorded. An "X" is placed in the center of the upper part of the sample with a marker. The sample is centered on the lower plate of FIT. The upper sheet is centered on the sample and the upper FIT plate is lowered at the top of the upper sheet. The upper plate is centered on the sample, so that the collection cylinder is centered on the "X" marked on the sample. An attack of 10 ml of synthetic menstrual fluid is emptied into the collection cylinder and the amount of time taken for the sample to acquire the fluid is measured and recorded. This time, reported in seconds (s), is the acquisition time for the sample. Simultaneous with the end of the acquisition time, a waiting period of 20 minutes begins. At the end of the waiting period, the rewet is measured by removing the upper FIT plate, then placing a pre-weighed stack of eight S22 blotters on the top sheet of the sample. The foam is placed on the paper and the weight is placed on top of the foam (foam and paper constitute a pressure of 3.4 kPa in the sample) for two minutes. Rewetting, reported in grams (g), is calculated by subtracting the initial weight of the stack of papers from the final weight of the stack of papers. This combination test is usually done in triplicate and the results are averaged. The structures of the present invention which have a y-directional profile in basis weight, density and SAP content, can be employed in any disposable absorbent article intended to absorb and contain body exudates, and which are usually placed or retained in proximity to the body of the user. Disposable absorbent articles include infant diapers, adult incontinence products, underpants, sanitary napkins, and other feminine hygiene products.

Exemplary Modes of the Invention The invention is illustrated herein by conducting a series of experiments in which unitary absorbent structures are produced and tested.

Example 1 (Samples A to C) Samples A to C are unitary absorbent cores of three layers, which were manufactured in a pilot air suspension line containing three forming heads. For this group of samples, the second forming head of the pilot line was modified to form the striped layers of the present invention. In samples A to C, the first twisted or lower layer comprised 70 g / m2 of pulp grade ND-416 (Weyerhaeuser Co.; Tacoma WA), 7 gsm bicomponent binder fiber (grade AL-Adhesion-C, 1.7 dtex x 4 mm, FiberVisions; Covington, GA) and carrier tissue (absorbent core wrap, 18 g / m2, Cellu Tissue Corporation; East Hartford, CT). In samples A to C, the third acquisition layer or higher comprised 35 gsm of polyester fiber 817 dtex x 6 mm, grade 376X2, Wellman, Inc., Johnsonville, SC) to which an emulsion binder was applied ( 6 g / m2, Airflex 192, Air Products Polymers, Allentown, PA).

Sample A serves as the control for this group because it was not produced by practicing the present invention. In Sample A, the average storage stratum comprised 50 g / m2 of HPF grade pulp (Buckeye Technologies, Memphis, TN), 50 g / m2 of Favor SXM 70 superabsorbent powder (Stockhausen, Inc., Greensboro, NC) and 7 g / m2 of bicomponent binder fiber grade AL-Adhesion-C (1.7 dtex x 4 mm). The present invention was used to construct the second medium storage layer for samples B and C. The objective was to maintain the weight of the second layer equal to that found in sample A, but to increase the base weight of the second layer by concentrating the material absorbent in an area located in the center of samples B and C. This was done by reducing the width of the second stratum and, concomitantly, fixing the total amount of absorbent material present in the stratum. Reducing the area over which the absorbent material was distributed, increased the base weight of the stratum. The standard product tread for these examples was 70 mm by 200 mm. While the gobal weight of the constant stratum is maintained, the width of the middle layer was reduced from 70 mm (full width, sample A) to 55 mm (sample B) to 40 mm (sample C). For sample A (control), the target basis weight was 243 g / m2 and the objective gauge was 2.85 mm, resulting in a target density of 0.085 g / cc. Samples B and C were also compacted uniformly to a target gauge of 2.85 mm. Figure 14 is a schematic drawing indicating how samples A to C were formed, stratum by stratum. Figure 14 indicates that the weight base and density of sample A should be constant across its width. However, Figure 14 also indicates that, compared to sample A, samples B and C should have regions of higher basis weight and density at their centers and regions of lower base weight and density at their edges. Figure 1 5 shows the base weight profiles of the direction-and they were measured for samples A to C. The basis weight for sample A is uniform. The basis weight of the edges for samples B and C is the same, indicating the absence of a contribution to the overall basis weight of the second storage stratum or medium. As indicated by the schematic drawings of Figure 14, the basis weight is the center of the increased unit absbbric cores from sample A to sample B to sample C. Samples A to C were compacted to the same. thickness in the line pi lotus suspension in air. Figure 1 6 shows the density profiles in the y-direction for samples A to C. Figure 1 4 shows the increase in density at the center as the basis weight was increased in the center to fixed thickness. Figure 1 6 shows the decrease in density at the edges as the basis weight decreased at the edges at a fixed thickness.

Example 2 (samples D to G) Samples D to g show how the present invention can be used to improve product performance over conventional technology.

Samples D and E are unitary absorbent cores of three strata, which were manufactured in a pilot air suspension line containing three forming heads. The first twisted or lower stratum for these samples comprised 101.8 g / m2 of pulp grade ND-416 (Weyerhaeuser Co, Tacoma WA), 8.9 g / m2 of bicomponent binder fiber (grade AL-Adhesion-C, 1.7 dtex x 4 mm, FiberVisions; Covington, GA) and carrier tissue (absorbent core wrap, 18 gsm, Cellu tissue Corporation, East Hartford, CT). The second storage layer or medium comprised 50 g / m2 of HPF grade pulp (Buckeye Technologies, Memphis, TN), 50 g / m2 of Favor SXM 70 superabsorbent powder (Stockhausen, Inc., Greensboro, NC) and 7 g / m2 of bicomponent binder fiber grade AL-Adhesion-C (1.7 dtex x 4 mm). The third tier of acquisition or above comprised 35 gsm of polyester strand fiber (17 dtex x 6 mm, grade 376X2, Wellman, Inc.; Johnsonville, SC) to which an emulsion binder (6 g / m2, Airlfex 192, Air Products Polymers, Allentown, PA) was applied. For sample D, the first forming head of the pilot line was modified to form the striped layer of the present invention. The standard product tread is 70 mm by 200 mm. For sample D, the first stratum was formed into two 22.3-mm lines with an opening of 25.4 mm between the lines. Sample E was constructed in the conventional manner to serve as a control. Note that the base weight and density in the center of sample D were less than the base weight and the density of the sample E. Both samples were compacted to a thickness of 2.97 mm.

Fig. 17A is a schematic drawing indicating how the sample was formed, stratum by stratum, Fig. 17B is a schematic drawing indicating how the sample E was formed, stratum by stratum. In Figures 1 7A and 1 7B, the longitudinal axis of the product is normal to the plane of the drawing. Figures 1 7A and 1 7B do not indicate the final view profiles of the actual finished products after they were compacted to the target thickness. Table 1 shows acquisition and rewet data for samples D and E. Addition was faster and rewet was lower for sample D compared to control, sample E. It is well known to those skilled in the art that the acquisition time can be a strong absorbent core density function. The lower density in the central portion of sample D responds for its shorter acquisition time.

Table 1 . Acquisition and rewet data for samples D and E Samples F and G are unitary absorbent cores of two strata, which were manufactured using a first Buckeye design laboratory pad (Buckeye Technologies, Mem phis, TN). For these samples, the forming screen of the first laboratory cushion modified to form the striped layers of the present invention These cores were formed head-first in the first laboratory pad (the upper layers of the cores were formed first and the lower layers of the cores were formed later) Sample G serves as the control for this pair of samples A top layer was formed in a top sheet material that also functioned as a carrier (a polypropylene ion yarn with a durable hydrophilic finish, 22 g / m2, Avgol Nonwoven I ndustries, Holon , Israel) This stratum comprised 92 g / m2 of fluff pulp (Foley Fluffs, Buckeye Technologies, Memphis, TN) and 1 0 g / m2 of bicomponent lignant fiber (Grade Al-Adhesion-C, 1 7 dtex x 4 mm , FiberVisions, Covington, GA) The present invention was used to construct the upper stratum for the upper stratum F The objective was to maintain the upper stratum weight equal to that found in Sample G, but to increase the base weight of the upper stratum. r by concentrating the absorbent material at the center of F This was done by reducing the width of the upper stratum and, concomitantly, fixing the total amount of absorbent material present in the stratum Reducing the area over which the absorbent material was distributed increased The base weight of the stratum The standard product tread for these samples was 70 mm by 200 mm While the overall weight of the stratum remained constant, the width of the upper stratum was reduced by 70 mm (full width, sample G). ) at 44 mm (sample F) In samples F and G, the bottom layer comprised 59 g / m2 of paper pulp (Foley Fl uffs, Buckeye Technologies, Mem ph is, TN), 7 g / m2 bicomponent binder fiber (AL-Adhesion-C grade, 1 7 dtex x 4 mm, FiberVisions; Covington, GA), 50 g / m2 of Favor SXM 70 superabsorbent powder (Stockhauses, Inc., Greensboro, NC). For sample G (control), the target basis weight was 240 g / m2 and the objective gauge was 2.67 mm, resulting in a target density of 0.090 g / cc. The sample F was also compacted uniformly to a target gauge of 2.67 mm. Figure 18 is a schematic drawing indicating how samples F and G were formed, stratum by stratum. Samples F and G were formed head-first in the previous laboratory, but their profiles are shown right in Figures 18A and 18B, respectively. In Figure 18, the longitudinal axis of the product is normal to the drawing plane. Table 2 shows acquisition and rewet data for samples F and G. Dryness of product, as measured by the rewet test, was better for sample F over control (Sample G). The absorbent material was concentrated in the central portion of the sample F, resulting in improved rewetting on the control. The acquisition was lower in the sample F compared to the control, sample G. It is well known to those skilled in the art that the acquisition time can be a strong function of absorbent core density. The greater density in the central portion of the sample F responds for the longer acquisition time.

Table 2. Acquisition and rewet data for samples F and G Example 3 (samples H and J): The following samples teach how the present invention can be used to maintain performance while reducing raw material costs. Samples H and J are unitary absorbent cores of three strata that were manufactured in a pilot line suspended in air containing three forming heads. The first twisted or lower stratum for these samples comprised specific amounts of pulp grade ND-416 (Weyerhaeuser Co., Tacoma WA). The first stratum for samples H and J contained 60 gsm of pulp ND-416. See Table 4. The first stratum for these examples also contained 7 gsm of bicomponent binder fiber (Grade AL-Adhesion-C, 1.7 dtex x 4 mm, FiberVisions, Covington, GA) and carrier tissue (absorbent core wrap, 18 g / m2, Cellu Tissue Corporation, East Hartford, CT).

Table 3. Product parameters and rewet data for samples H to K The second storage layer or medium comprised 50 g / m2 of HPF grade pulp (Buckeye Technologies, Memphis, TN), 50 g / m2 of Favor SXM 70 superabsorbent powder (Stockhausen, Inc., Grreensboro, NC) and 7 g / m2 of bicomponent binder fiber grade AL-Adhesion-C (1.7 dtex x 4 mm). The third acquisition layer or higher comprised 35 g / m2 of polyester strand fiber (17 dtex pf x 6 mm, grade 376X2, Wellman, Inc., Johnsonville, SC) to which an emulsion binder was applied (6 g / m2, Airflex 192, Air Products Polymers, Allentown, PA). For this group of samples, the first forming head of the pilot line was modified to form the striped layers of the present invention, the standard product tread is 70 mm by 200 mm. For sample H, the first layer was formed in a 55 mm wide strip centered around the longitidinal axis of the product. For sample J, the first stratum was formed in a 40 mm wide strip centered around the longitudinal axis of the product. Table 3 shows the base and width weights for the lower strata for samples H and J.

Samples H and J were uniformly compacted at a target density of 0.085 g / cc. The target basis weight in the central portions of samples H and J was 233 g / m2. Figure 1 9 shows rewet data for samples H and J as a function of base weight and width of the lower twisted layer. Figure 1 9 shows that the rewet is essentially flat with respect to the width of the stratum. Assuming that the performance of rewetting shown here is feasible, examples with the narrowest width would be favored based on raw material costs.

Example 4 Seven commercially available brand diaper products (products 1-7) were tested by containing% SAP in the absorbent core, absorbency, rewet retention and third acquisition time. The results are summarized in Table 4.

Table 4 Comparison of the data in Table 4 with the data in Tables 5 and 6 reveals that the absorbent systems comprising y-shaped profiled absorbent structures have PHASE values considerably higher than any of the commercial absorbent articles tested.

Example 5 The absorbent samples tested in Example 4 were used for reference to compare the performance of systems without profiled structures in a y-direction (Example 4) with systems containing y-shaped profiled structures (Examples 5 and 6). ).

The following raw materials were used as structural components of the samples described in Examples 5 and 6: a) Foley Fluff (FF) - bleached southern softwood kraft fibers (BSSK) from Buckeye Technologies; Memphis, Tennessee; b) ND416 compressible pulp available from Weyerhaeuser Company; Tacoma, Washington; c) chemically crosslinked (CS) fibers, such as those described in U.S. Pat. 5,190,563 when treating southern softwood kraft pulp with citric acid and sodium hypophosphite. The fibers had WRV of approximately 40% and curl factor of approximately 0.5; d) polyethylene terephthalate (PET) fibers which have the name of Fillwell 093MR, Wellman PET 376X2, having a thickness of 16.7 dtex per fiber (dtexpf) and length of 6 mm, available from Wellman International Limited; Mullagh, Kells, County Meath, Ireland; e) superabsorbent polymers: - FAVORMR SXM 3950, obtained from Stockhausen GmbH & CoKG .; Krefeld, Germany. - FAVORmr SXM 9100, obtained from Stockhausen GmbH & CoKG .; Krefeld, Germany - K-SAM R MG-2600, obtained from Kolon Chemical Co., LTD .; Kwacheon-City Kyunggi-Do, Korea; - K-SAMMR MG-3500, obtained from Kolon Chemical Co., LTD .; Kwacheon-City Kyunggi-Do, Korea; f) Licontrol ™ non-woven acquisition stratum having a basis weight of 48 g / m2, reference number 381002-0000 of Jacob Holm Industries; Alsace, France SAS; g) AirFlex ™ latex emulsion available from Air Products Polymers, L.P .; Allentown, Pennsylvania; h) curled binder fiber, bicomponent T255MR having a thickness of 2.3 dtexpf and length of 6 mm available from Kosa; Houston Texas; i) FiberVision bicomponent binder fiber having a thickness of 1.7 dtexpf and length of 6 mm, available from FiberVisions; Varde, Denmark. The absorbent samples used in Example 5 each consisted of an upper layer and a lower layer, both layers having a rectangular shape. Each upper stratum was 10 cm wide and 20 cm long, while each lower stratum was 10 cm wide and 40.6 cm long. To test the acquisition and rewet time of each absorbent sample, the upper layer was placed in the upper part of the lower layer, so that the front edges of both sheets were on the same line. For the absorbent sample "L" and "M", the same lower sheet material X612 was used. Sample "N" consisted of higher (DX119) and lower (DX122) higher basis weight sheets described in this Example. The lower layer material, X612, basis weight of 330 g / m2, and used in Example 6, was produced in a commercial air suspension machine M &J by forming an absorbent in Cellutissue 3024, a carrier tissue of 18 g / m2. The absorbent was formed in four steps. First a homogeneous stratum comprised by 37 g / m2 of pulp fibers ND416, 92. 3 g / m2 of FavorMR S M 3950, and 4.0 g / m2 of bicomponent fiber T-255MR (2.3dtexpf). A second homogeneous layer comprised of 37 g / m2 of pulp fibers ND416, 92.3 g / m2 of FavorMR SXM 3950 and 4.0 gsm of fiber of thread T-255 (2.3dtexpf). A third homogeneous layer comprised of 38.5 g / m2 of pulp fibers ND416 and 6.9 g / m2 of fiber of thread T-255 (2.3dtexpf). The water in an amount of 49.1 g / m2 was atomized in the upper part of the third layer before the drying and curing step. Sample L was made using a top layer material produced in a Danweb air suspension pilot machine in the following manner: 48 g / m2 using the non-woven acquisition layer I type Licontrol ™ as a forming die. The absorbent structure was formed on the spunbond side of the two layers or tissues. The raw materials were mixtures in a homogeneous manner consisting of 144 g / m2 of FF pulp fibers, 150 g / m2 of FavorMR SXM 9100 and 6.0 g / m2 of FiberVision (1.7 dtex). The total base weight was 348 g / m2. Sample M was made using an upper stratum material produced in a Danweb air suspension pilot machine. 48 g / m2 of non-woven acquisition stratum type Licontrol ™ was used as a training sheet. The absorbent structure formed on the united side! by spinning the two strata or tissues. The raw materials were homogenously mixed consisting of 144 g / m2 of CS pulp fibers, 150 g / m2 of Favo | rMR SXM 9100 and 6.0 g / m2 of FiberVision (1.7 dtex). The total basis weight was 348 g / m Sample N consisted of DX119 material as an upper sheet and DX122 material as a lower sheet. The DX119 material was made as follows: A tissue based on cellulose, Cellutissue 3024 18 g / m2, was first applied and used as a transfer medium / carrier for the subsequent material. The next stratum consisted of a uniform mixture of 130 g / m2 of southern softwood pulp fibers (Foley Fluff), 103.5 g / m2 of MG 2600 Kolon superabsorbent and 7.5 g / m2 of self-adhesive bicomponent fiber with a polypropylene core and polyethylene sheath (Fiber Visions 1.7 dtexpf / 4 mm cutting). The next layer consisted of a uniform mixture of 130 g / m2 of Foley Fluff, 103.5 g / m2 of Kolon MG 2600 and 7.5 g / m2 of FiberVision bicomponent fiber, 1.7 dtexpf / 4 mm cutting. The last layer or higher was 42 g / m2 of polyamide terephthalate fibers WellmanMR PET 376 x 2, 16.7 dtexpf and 8 g / m2 of latex binder Air Products AF 124 used at 10 percent solids. The weft was densified at 0.07 g / cc before curing. The total base weight of the material was 547 g / m2. DX122 material was made as follows: A tissue based on cellulose, Cellutissue 3024 18 g / m2, was first applied and used as a transfer medium / carrier for the subsequent material. The next layer consisted of a uniform mixture of 117 g / m2 of highly compressible softened pulp fibers (ND416), 85 g / m2 of high permeable superabsorbent (Kolon MG 2600) and 11 g / m2 of self-adhering bicomponent fiber with a polypropylene core and polyethylene sheath (Fiber Visions 1.7 dtexpf / 4 mm cutting). The next The layer consisted of a uniform mixture of 17 g / m2 of N D41 6, 201 g / m2 of Kolon MG 2600 and 4 g / m2 of FiberVision bicomponent fiber, 1.7 dtexpf / 4 m of cutting. The last layer or higher was 5 g / m2 of binder added in the latex binder Air Products AF 1 24 used to 14 percent solids. The screen was densified at 0. 1 5 g / cc before curing. The total base weight of the material was 550 g / m2.

Table 5. Properties of samples L to N The data in Tables 4, 5, 7 and 1 0 clearly demonstrate the superiority of bipolar systems comprising profiled structures in a directional manner over absorbent systems without such profiled structures.

EXAMPLE 6 The absorbent samples tested in Example 6 consisted each of an upper stratum and a lower stratum, both having strata rectangular shape. Each upper layer has a y-directional profile described in Table 5 and was 10 cm wide and 20 cm long, while each of the lower sheet was 10 cm wide and 40.6 cm long. To test the time of acquisition and rewetting of each sample, the upper sheet was placed on the upper part of the lower sheet, so that the fornitive edges of both sheets were on the same line. The lower stratum material, called X612, was the same as described in Example 5. Sample O was made using an upper stratum material produced in a Danweb air suspension pilot machine in the following manner: the stratum was used of non-woven acquisition Licontrol ™ as a training sheet. The first stratum was formed on the spun-bonded side of the two non-woven strata. The first stratum formed was the region of high density zone A as 5.1 cm, separated by 5.1 cm of dashes running in the MD direction. The stripes were composed of 175 gsm of ND416 pulp fibers, 281 g / m2 of FavorMR SXM 9100 and 14.0 g / m2 of FiberVision bico fibers (1.7 dtexpf). These materials were mixed homogeneously. The second layer filled zone B. It consisted of 62 g / m2 of FF pulp fibers, 66 g / m2 of FavorMR SXM 9100 and 4.0 g / m2 of FiberVision bico fibers (1.7 dtexpf). These materials were mixed homogeneously filling the areas between the high density zone A region. The total basis weight was 348 g / m2. Sample P was made using an upper stratum material produced in a Danweb air suspension pilot machine in the following way: the non-woven acquisition stratum Licontrol ™ was used as a training sheet. The first layer was formed on the joined side with spinning of the two non-woven layers. The first layer formed was the region of high density zone A as 5.1 cm, separated 5.1 cm of dashes running in the MD direction. The stripes were composed of 175 gsm of ND416 pulp fibers, 281 g / m2 of FavorMR SXM 9100 and 14.0 g / m2 of FiberVision bico fibers (1.7 dtexpf). These materials were mixed homogeneously. The second layer filled zone B. consisted of 62 g / m2 of CS pulp fibers, 66 g / m2 of FavorMR SXM 9100 and 4.0 g / m2 of FiberVision bico fibers (1.7 dtexpf). These materials were homogenously mixed filling the areas between the high density zone A region. The total basis weight was 348 g / m2. Sample Q was made using a top layer material produced in a Danweb air suspension pilot machine in the following manner: the Licontrol ™ non-woven acquisition stratum was used as a forming sheet. The first layer was formed on the joined side with spinning of the two non-woven layers. The first layer formed was the region of high density zone A as 5.1 cm, separated 5.1 cm of dashes running in the MD direction. The stripes were composed of 175 gsm of ND416 pulp fibers, 281 g / m2 of FavorMR SXM 9100 and 14.0 g / m2 of FiberVision bico fibers (1.7 dtexpf). These materials were mixed homogeneously. The second layer filled zone B. It consisted of 62 g / m2 of synthetic fibers of 6 mm Fillwell 093MR Wellman PET 376X2 16.7 dtexpf, 66 g / m2 of FavorMR SXM 9100 and 4.0 g / m2 of fibers of bico FiberVision ( 1.7 dtexpf). These materials were meclados homogenously filling the areas between the high density zone A region. The total basis weight was 348 g / m2.

Table 6 Areas A and B, base weights and densities for each zone were calculated values from total weight and volume measurements.

Table 7 Analyzes of the data in Tables 4, 5, 6 and 7 reveal that the absorbent samples comprising directional and directional absorbent structures have PHASE values considerably greater than any of the commercially available and tested absorbent articles, as well as m Absorbent samples without profile and directional. The highest PHASE values were obtained with the y-profiled structures, in which the B areas comprised either cross-linked cellulose fibers (CS) or PET fibers (WellmanM R PET 376X2 1 6.7 dtexpf). The upper-and-profile sheet components of samples P and Q were tested for wet integrity, softness and flexibility. The results are shown in Table 8.

Table 8 Example 7 The absorbent samples tested in Example 7 consisted each of an upper stratum and a lower stratum, both sheets having a rectangular shape. The upper stratum was material U nicore 8902, which is commercially available from Buckeye Technologies I nc. It was 9 cm wide and 20 cm long. The lower sheet was 10 cm wide and 35.6 long. To test the time of acquisition and rewetting of each absorbent system, the upper stratum was placed in the lower stratum, so that the front edges of both strata were in the same line. Sample R contained a lower layer made in a first laboratory cushion in the following manner: 1. A carrier tissue (Cellutissue 3024, a cellulose tisol of 1 8 g / m2) was laid. 2. The first set of material fields was deposited. This was achieved by using a different variant. The variant grid consisted of fields open 1 0 m m and alternating locks. The first set of deposited material fields consisted of Aracruz Eucalyptus fiber in a weight of 86 g / m2 and FiberVisions 1 .7dtexpf / 4 μm bicomponent fiber at a weight of 1 2 g / m2. These weights represent weights of material in the first fields of 1 0 mm width only. The overall average gsm for the pad is, therefore, the average of these g / m2's in the field only. 3. The variant grid was then moved 1 0 mm in the transverse direction, so that the open areas of the grid were then on the empty fields of the pad. The second set of fields of material were then deposited. The deposited material consisted of Weyerhauser N D41 6 fiber at a weight of 86 g / m2, fiber bicomponent FiberVisions 1 .7 dtexpf / 4mm at a weight of 1 2 g / m2, and polymer exceeds Stockhausen SXM70 bsorbent at a weight of 368 g / m2. The overall average g / m2 for the pad is, therefore, half of these g / m2's in field only. 4. The resulting structure was then densified using a laboratory roll press. The resulting density for the first set of material fields was 0.06 g / cc. The resulting density for the second set of material fields was 0.28 g / cc. 5. A latex lifting atom was then applied to the structure above stratum 2. The latex used was Air Products Airflex 1 24. The latex lifting atom was a mixture of 1 0 percent solids. This mixture also contained surfactant Aerosol OT (75 percent) added at a level of 0.1 percent. The atomized mixture resulted in a latex of 2 g / m2 of solids added to the sample. 6. The sample was then dried / cured in an oven (Lindberg / Blue M) for 25 minutes at 150 ° C.

Table 9 Table 10 Sample S contained a lower layer made in a first laboratory pad as follows: 1. A carrier tissue was laid. This material was Cellutissue 3024, a cellulose tissue of 18 g / m2. 2 Stratum 1 was deposited This stratum consisted of a uniform mix of Weyerhauser ND41 6 fiber at a weight of 86 g / m2, FiberVisions 1 55 dpf / 4 mm bicomponent fiber at a weight of 1 2 g / m2, and superabsorbent polymer Stockhausen SXM70 at a weight of 1 84 g / m2 3 The resulting structure was then densified using a laboratory rod press. The reusable density for the structure was then 0 23 g / cc 4. Then a latex atomizer was applied to the structure above stratum 1 The latex used was Air Products Airlfex 1 24 The latex lifting atom was a mixture of 1 0 percent solids This mixture also contained surfactant Aerosol OT (75 percent) added at a level of 0 1 percent The atomized mixture resulted in a latex of 2 g / m2 of solids adhered to sample 5 The sample was dried / cured in an oven (Lmdberg / Blue M) for 25 m inutes at 1 50 ° C As seen from the data in Table 9, the sample R with lower sheet shaped and directional has a significantly higher PHASE value than the "S" control sample Although the invention has been described in detail with specific reference to the preferred embodiments of the same, the invention is capable of other modalities and of different modalities, and their details are capable of modifications in several obvious aspects. As will be readily apparent to those skilled in the art, variations and modifications may be made while remaining within the spirit and scope of the invention. Accordingly , the disclosure, description and foregoing figures are for illustrative purposes only, and in no way limit the invention, which is defined solely by the claims.

Claims

REIVIN DICACIONES 1 . A unitary absorbent structure with a y-directional profile comprising a plurality of layers produced by a continuous series of unitary operations of one or more materials selected from fibers, functional particles, binders, carrier tissue and additives, and wherein the less a stratum contains functional particles, and wherein the structure has a vertical profile and comprises at least first and second zones arranged in contact with each other, wherein the first zone has one or more of a greater density, a content of greater functional particles and a greater basis weight than the second zone. 2. A unitary absorbent structure with a y-directional profile comprising a stratum or a plurality of strata, and containing functional particles and having a y-directional profile comprising first and second zones disposed in contact with each other, wherein the first zone has one or more of a greater density, a greater functional particle content and a higher basis weight than the second zone, the structure having a PHASE greater than about 50. 3. The structure of claims 1 or 2, wherein the first zone has a greater density and a greater basis weight than the second zone. 4. The structure of one of the subdivisions 1 -3, where the first zone has a higher density and a higher content of functional particles than the second zone. 5. The structure of one of claims 1 -4, wherein the first zone is disposed at the lateral edge of the absorbent structure. 6. The structure of one of claims 1-5, further comprising a third zone and a fourth zone, wherein the third zone has a higher density and a higher functional particle content than the second and fourth zones. The structure of one of claims 1-6, wherein at least one stratum has a larger surface area with a surface area, which is less than 80 percent of the surface area of a corresponding larger surface of another stratum. 8. The structure of one of claims 1-7, wherein the y-directional profile of the structure is a result of a stratum only with a y-directional peril. 9. The structure of one of claims 1-8, wherein the y-directional profile of the structure is a result of two or more strata with y-directional profiles. 10. The structure of one of claims 1-9, wherein at least one stratum is of substantially uniform density and basis weight. 11. The structure of one of claims 1-10, wherein the structure has a z-directional profile. 12. The structure of one of the previous claims, further comprising fibers. The structure of claim 12, wherein the fibers have a moisture retention value of at least 80 percent. The structure of one of claims 12 and 13, wherein the fibers have a curl of at least 25 percent. 15. The structure of one of claims 12-14, wherein the fiber comprises both natural and synthetic fibers. 16. The structure of one of the previous claims, further comprising a binder. The structure of claim 16, wherein the binder is selected from the group consisting of liquid binders, including latex binders, thermoplastic powders, thermoplastic fibers, bicomponent fibers and mixtures thereof. 18. The structure of one of claims 16 and 17, wherein the binder is present in an amount that is between about 0.1 percent and about 10 percent by weight of the structure. 19. The structure of one of the previous claims having an acquisition layer in fluid communication with the first zone, the second zone or both with the first zone and the second zone. The structure of claim 19, wherein the acquisition stratum comprises synthetic matrix fibers bonded with a binder, the matrix fibers having a length from about 2 to about 15 mm. The structure of one of the previous claims, wherein the basis weight of the first zone is from 50 g / m2 to approximately 100 g / m2. 22. The structure of one of the previous claims, wherein the density of the first zone is from about 0.15 g / m3 to about 0.25 g / m3. 23. The structure of one of the previous claims, wherein the content of functional particles of the first zone is from about 10 percent to about 90 percent by weight of a superabsorbent material. 24. The structure of one of the previous claims, wherein the basis weight of the second zone is from about 0. 1 g / m2 to about 800 g / m2. 25. The structure of one of the previous claims, wherein the content of functional particles in the second zone is from about 0 percent to about 70 percent. 26. The structure of one of claims 1 and 3-25 having an FAS E greater than about 80. 27. The structure of one of the previous claims having wet integrity greater than about 4.0 m N / g / m2. 28. The structure of one of the previous claims having smoothness greater than about 8.0 / J. 29. The structure of one of the previous claims having a flexibility greater than about 70 / N. 30. The structure of one of the previous claims, wherein the structure has been produced by a continuous series of unit operations, where each stratum is formed in a one-way operation from one or more selected materials of fibers, particles of functional, binding agents, carrier tissue and additives. 31 A disposable absorbent article comprising: (A) a liquid permeable upper sheet, (B) a liquid-impervious backsheet, (C) between the upper sheet and the backsheet and in fluid communication with the upper sheet an absorbent structure of one of claims 1 -29, and, optionally, (D) between (C) and (B) and in fluid communication with (C) a storage stratum comprising fibers and functional particles, where a larger surface area of (C) in fluid communication with a surface greater than ( D) has a surface area, which is less than 80 percent of the surface area of a corresponding larger surface of (D). 32. The article of claim 29, wherein (C) comprises: (1) an acquisition layer profiled in a y-directional manner; and (2) a layer of acquisition and storage profiled in a y-directional manner that has a higher content of functional particles than that of the acquisition stratum. 33. The article of claim 29 or 30, wherein the article is a nappy diaper, a training underpants, an adult incontinence device, or a sanitary napkin. 34. The article of one of claims 29-31 having a PHASE of 50 or greater. 35. The article of claim 32 having a PHASE of 80 or greater. 36. The article of claim 33 having a PHASE of 1 00 or greater. 37. The article of claim 34 having a PHASE of 1 80 or greater. 38. A process for the production of a unitary absorbent structure with a y-directional profile comprising a plurality of strata produced by a continuous series of unit operations and which contains functional particles and has a y-directional profile comprising first and second zones arranged in contact with each other, wherein the first zone has one or more of a greater density, a greater content of functional particles and a greater basis weight than the second zone, the process comprising: (1) forming a first stratum A comprising fibers and, optionally, functional particles, and (2) forming a second stratum B comprising fibers and functional particles, so that a larger surface of B is in contact with a fluidization with a larger surface area of A and the y-directional length of B is less than the y-directional length of A. 39. A process for the production of a unitary absorbent structure with a profi It is a directional system comprising a plurality of layers produced by a continuous series of one-way operations, and which contains functional particles and has a y-directional profile comprising first and second zones disposed in contact with each other, wherein the first The zone has one or more of a greater density, a higher functional particle content and a higher basis weight than the second zone, the process comprising: (1) forming a first stratum A comprising fibers and, optionally, particles functional, and (2) forming a second stratum B comprising fibers and functional particles, so that the first and second zones arranged in contact with each other are formed, wherein the first zone has a higher density and a higher functional particle content than the second zone. 40. The process of one of claims 38 or 39, wherein the strata are formed in a wire forming a suspension process in air and the first and second stratum B areas are formed by manipulating a vacuum under the wire This is so that there is a greater differential pressure under the first zone than under the second zone, with the consequent deposition of a greater amount of fiber and functional particles in the first zone than in the second zone. 41 The process of claim 38 or 39, wherein the strata are formed in a wire forming an air suspension process of fibers and functional particles distributed from a forming head and the first and segmented zones of stratum B are formed by partially blocking the distribution in the second zone but not the first zone. SUMMARY Absorbent structures are described which have a y-directional profile in density and content of superabsorbent polymer particles. The structures include areas having higher density and higher content of superabsorbent polymer particles and areas having lower density and lower content of superabsorbent polymer particles. Also described are methods for preparing absorbent structures having a y-directional profile in density and content of superabsorbent polymer.