MXPA98007930A - Absorbent article comprising topsheet, backsheet, and absorbent core with liquid-transferring layer near backsheet - Google Patents

Abstract

In an absorbent article (10) including an absorbent structure (32) positioned between the top sheet (12) and the back sheet (14), the absorbent structure (32) includes an upper layer (28), a lower layer (30), and an elongate, absorbent core (40), which is formed from cellulosic fibers and from distributed particles of a super-absorbent polymer (SAP), and which has an elongate, central portion (40) with an absorbency under load (AUL) not less than about 12 grams/gram. Having a basis weight not more than about 150 grams per square meter and an absorbency under load (AUL) not more than about 6 grams/gram, the lower layer (30) has a minimal absorbency but is capable of transferring to a lower surface of the absorbent core (32) a liquid permeating the lower layer (30) from the absorbent core (32).

Description

ABSORBENT ARTICLE COMPRISING A TOP SHEET, ONE BACKING SHEET AND AN ABSORBENT CENTER WITH A LAYER OF TRANSFER OF LIQUID NEAR THE BACKING SHEET FIELD OF THE INVENTION This invention pertains to an absorbent article, such as a disposable diaper, comprising a top sheet and an absorbent core having a liquid transfer layer near the back sheet, to provide improved efficiency of the absorbent center.

BACKGROUND OF THE INVENTION Commonly, the absorbent article, such as a disposable diaper or an adult incontinence article, consists of a liquid-permeable top sheet, a liquid-impermeable backing sheet and an absorbent core formed of cellulose fibers, which are typically pooled fibers of soft wood pulp and particles distributed from a superabsorbent polymer (SAP) (Superabsorbent polymer) and having an absorbent center placed between the top sheet and the backing sheet. It is known how to provide an absorbent article with one or more layers formed of cellulose fibers and other materials to perform various liquid absorbent, liquid distribution and cushioning functions.

P1631 / 98MX In this way, it is known how to place a top layer formed of cellulose fibers between the top sheet and a top surface of the absorbent center. The upper layer absorbs some of the liquid that permeates the upper layer from the upper sheet. Also the upper layer transfers the rest of the liquid to the upper surface of the absorbent center, mainly by means of a cotton packing action. The upper layer placed between the upper sheet and the absorbent center is also known as a cotton packing layer, transfer layer or acquisition layer. Also, it is known to wrap the absorbent center of the absorbent article with one or more layers formed of cellulose fibers, such as one or more layers of tissue. Generally, each wrapping layer is capable of absorbing a quantity of the liquid permeating the wrapping layer. This invention has resulted from the constant efforts to improve an article with a liquid-permeable top sheet, a liquid-impermeable backing sheet and an absorbent center as described above, to improve the liquid storage efficiency of the absorbent center .

SUMMARY OF THE INVENTION The invention is the result of the realization of P1631 / 98MX an absorbent article having a permeable topsheet, a liquid-impermeable backsheet and an absorbent center, as described above, that can be efficiently upgraded used to store a liquid, such as urine, if the The absorbent structure is provided with a lower layer having a limited capacity to absorb the liquid permeating the lower layer from the absorbent center, but having an improved ability to transfer the liquid permeating the lower layer from the absorbent center to a lower surface of the absorbent center. This invention provides an absorbent article consisting of a liquid pervious topsheet, a liquid impervious backsheet, and an absorbent structure that is positioned between the topsheet and the backsheet including the absorbent center. The absorbent structure further includes a bottom layer having minimal absorbency but providing means for transferring the liquid permeating the lower layer from the absorbent center to the lower surface of the absorbent center. Specifically, the invention contemplates that the lower layer has a basis weight of not more than about 150 grams per square meter and an absorbency under load (AUL) not greater than about 6 grams / gram.

P1631 / 98MX In addition, the absorbent structure may include a top layer, as is known in the above absorbent articles. If it is included, the upper layer provides means to absorb some of the liquid permeating the upper layer from the upper sheet and to transfer it to the upper surface of the absorbent center, the remainder of the liquid permeates the upper layer from the upper sheet. This invention is operative even if the top layer is included or not. For the absorbent center to have sufficient absorbency to take advantage of this invention, the invention contemplates that the absorbent center is formed of cellulose fibers and of distributed particles of a superabsorbent polymer to have an elongated central portion with an absorbency under load (AUL) not less than about 12 grams / gram. In a preferred embodiment, the absorbent center has a front end, a rear end and two fins projecting from the elongated central portion, near the front end. In a preferred embodiment, the superabsorbent polymer (SAP) is present on the upper surface in essentially no concentration and in each of the fins in a concentration of about one-half the concentration of the superabsorbent polymer (SAP) throughout the portion central P1631 / 98MX elongated. If the lower layer is formed of cellulose fibers, the base weight of the lower layer must be suitably selected so that the lower layer has a limited capacity to absorb the liquid permeating the lower layer from the absorbent center, but for the The lower layer has an improved ability to transfer the liquid that permeates the lower layer from the absorbent center to a lower surface of the absorbent center. Desirably, the absorbent center has a higher density, which is within the limits of about 0.12 grams per cubic centimeter to about 0.22 grams per cubic centimeter. Desirably, the lower layer when formed of cellulose fibers has a comparatively lower density that is within the range of about 0.06 grams per cubic centimeter to about 0.12 grams per cubic centimeter. Preferably, the lower layer is a layer of air-laid pulp having a basis weight of approximately 105 grams per square meter or a layer layer of air-laid, triple, folded pulp, each layer having a basis weight of approximately 35 grams per square meter. Alternatively, the lower layer is one, P1631 / 98MX tissue layer, triple, folded, either coated or uncoated, each layer has a basis weight of approximately 37 grams per square meter. In an alternative configuration contemplated by this invention, each of the lower and upper layers is a layer of tissue having a basis weight of approximately 16 grams per square meter. In another alternative, the lower layer is a nonwoven web made of cellulose, synthetic polymer or synthetic conjugate fibers or mixtures of these fibers or of an open cell synthetic polymer foam. Preferably, to stabilize the absorbent center, the bottom layer has a wet strength no less than about 0.04 kilonewtons per meter (kN / M) in the machine or machine direction, and the lower or upper layers they extend beyond their ends and are joined together at one or both ends.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a fragmentary, perspective view of a disposable diaper exemplifying an absorbent article according to this invention, in an assembled condition. Figure 2 is a perspective view, P1631 / 98MX fragmented of the disposable diaper of Figure 1 in a flat condition. Figure 3 is a fragmentary sectional view taken along line 3-3 of Figure 2, in the direction indicated by the arrows. Figure 4 is a fragmentary, analogous sectional view taken through the absorbent article according to prior technology.

DETAILED DESCRIPTION OF THE PREFERRED MODALITY As shown in Figures 1, 2 and 3, a disposable diaper constitutes the preferred embodiment of this invention. According to this invention, the disposable diaper can store a liquid such as urine, with improved efficiency. The disposable diaper may have the dimensions suitable for use in infants or for use in adults. If you have dimensions for adult use, the disposable diaper can also be called an incontinence article. It can be noted that this invention can also be wound in the form of a bandage or in another absorbent article different from the disposable diaper. Broadly, the disposable diaper consists of a liquid-permeable upper sheet 12 of the known kind, a back-sheet 14 impermeable to the P1631 / 98MX liquids of the known kind, and an absorbent structure 16 placed between the upper sheet 12 and the backing sheet 14. The disposable diaper 10 has tape fasteners 18 of the known kind, elastic band for the waist 20 of the known kind, and other known characteristics outside the scope of the invention. The upper sheet 12 and the backing sheet 14 are attached with adhesives around their outer edges 22 of the disposable diaper 10, in a known manner, for, in this way, encapsulating the absorbent structure 16. The upper sheet 12, which can also be called a leaflet, can be made of a non-woven web of cellulose fibers, synthetic polymer fibers or Cellulose blends and synthetic polymer fibers and can be opened. The backing sheet 14 may be made of a synthetic polymer film, such as a polyethylene film. The details of the upper sheet 12 and the backing sheet 14 are outside the scope of this invention. Except for the illustration and as described herein, the disposable diaper 10 may be substantially similar to the disposable diaper disclosed in U.S. Pat. for Huffman et. No. 5,403,301, the disclosure of which is incorporated herein by reference. In the preferred embodiment, the absorbent structure 16 includes an upper layer 28 near the sheet 12 P1S31 / 98MX upper, and a lower layer 30 near the backing sheet 14, and an absorbent center 32 positioned between the upper layer 18 and the lower layer 30. As shown in Figure 3, the absorbent center 32 has an upper surface 34 near the upper layer 18 and a lower surface 36 near the lower layer 30. As shown in Figure 2, the absorbent center 32 has a central portion 40, elongated with a front end 42 and a rear end 44, together with two fins 46 near the forward end 44. In an alternative embodiment (not shown) the upper layer 28 is omitted. The upper layer 28 provides means for absorbing some liquid such as urine, which permeates the upper layer 28 from the upper sheet 12 and for transferring it to the upper surface 34 of the center 32 absorbent, the rest of the liquid permeates the upper layer 28 from the upper sheet 12. Preferably, the upper layer 28 is made of a non-woven web, either carded or bonded with air, as is made of polyester (polyethylene terephthalate) fibers, polyolefin or synthetic conjugate fibers or mixtures of these fibers, with a base weight of approximately 40 grams per square meter, and with a width of approximately 76 millimeters. Alternatively, the upper layer 28 is a layer of tissue formed from cellulose fibers with a basis weight P1631 / 98MX of approximately 16 grams per square meter, with a width of approximately 90 millimeters, and with a sufficient length to cover the absorbent center 32 over its entire length. In an alternative embodiment (not shown) wherein the top layer is a nonwoven web, as noted above, the top layer 28 has a length sufficient to cover a part, but not the entire length of the absorbent center. The absorbent center 32 is formed in a known manner, by a cellulose fiber package formation process, such as wood pulp and distributed particles of a superabsorbent polymer (SAP) of a known class. The superabsorbent polymer (SAP) preferred is a Celanese IM-4510 cross-surface superabsorbent polyacrylate, which is commercially available from Hoechst-Celenese of Portsmouth, Virginia. In the preferred embodiment, about 10 grams of soft wood pulp and about 7 grams of superabsorbent polymer (SAP) are used to form the absorbent center 32 to have a surface layer of soft wood pulp with a basis weight of about 40. grams per square meter on the upper surface 34, so that it has a density within the limit of approximately 0.12 grams per centimeter P1631 / 98MX cubic at about 0.22 grams per cubic centimeter, preferably a density of about 0.17 grams per cubic centimeter, to have a basis weight of about 800 grams per square meter along the central, elongated portion 40, and to have an absorbency under load (AUL) not less than about 12 grams / gram along the central portion 40, elongated. In general, due to the manufacturing variants, the absorbency under load (AUL) of the absorbent center can be controlled with an accuracy of approximately + -3 grams / gram. In a preferred embodiment, the absorbent center 32 is formed so that the superabsorbent polymer (SAP) is present in, essentially, a concentration in the surface layer on the upper surface 34, at a concentration sufficient to reach the absorbency under load (AUL ) indicated above along the central, elongated portion, and in each of the fins 46 at a concentration that is half the concentration of the superabsorbent polymer (SAP) along the elongated central portion 40. In accordance with this invention, the lower layer 30 has a minimum capacity for storing the liquid, but provides means for transferring the liquid, such as urine, which permeates the lower layer 30.

P1631 / 98MX from the absorbent center 32 towards the lower surface 36 of the absorbent center 32. Specifically, this invention contemplates that the lower layer 30 has an absorbency under load (AUL) not greater than about 6 grams / gram. In general, due to manufacturing variants, the absorbency under load (AUL) of the lower layer can be controlled with an accuracy of approximately H-1 grams / gram. Although the lower layer 30 may have a cotton packing action, the cotton packing action is not necessary. It is desirable that if the lower layer 30 is formed of cellulose fibers, the lower layer 30 has a density within the range of about 0.06 grams per cubic centimeter to about 0.12 grams per cubic centimeter. Compared to the previously described, comparatively higher density of the absorbent center 32, the lower layer 30 has a comparatively lower density. For the purposes of this invention, the absorbency under load (AUL) of an absorbent product refers to the amount of synthetic urine absorbed by several pilot samples of the absorbent product, if each pilot sample in a sample holder is immersed in synthetic urine, while each pilot sample submits P1631 / 98MX at a pressure of approximately 0.51 psi (713.2 grams per square meter), for a foaming time of approximately 10 minutes, and if each pilot sample and its sample holder are drained for approximately 60 seconds. Several pilot samples are used for each absorbent product, each pilot sample is cut from the absorbent product by a two inch diameter die. For each absorbent product, the average absorbency under load (AUL) for the pilot samples cut from the absorbent product is taken as the absorbency under load (AUL) for the absorbent product. For purposes of this invention, synthetic urine is prepared by following the instructions included in Synthetic Urine Concentrate, Catalog No. 8362, which is commercially available from Ricca Chemical Co. of Portsmouth, Virginia. Alternatively, a one percent weight aqueous solution of sodium chloride can be used as the synthetic urine. Several sample holders are used, one for each pilot sample, each sample holder having a known weight within the accuracy of approximately H-0.03 grams. Different weights are used, one for each pilot sample, each weight is designed to apply a pressure of 713.2 grams (+ -0.03 grams) per square meter. A balance with a P1631 / 98MX precision of + - 0.01 grams. For each pilot sample, the absorbance under load (AUL) is calculated by subtracting the dry weight of the pilot sample and its sample holder from the wet weight thereof, after the pilot sample and its fastener have been immersed in synthetic urine , while the pilot sample was subjected to a pressure of approximately 0.5 psi (713.2 grams per square meter) for a pumping time of approximately 10 minutes, and then drained for approximately 60 seconds. A first configuration contemplated by this invention for the lower layer 30 is an air-laid, triple, folded layer of wood pulp with each layer having a basis weight of approximately 35 grams per square meter, each layer with a density of approximately 0.08. grams per cubic centimeter, with a total weight of approximately 4 grams. With the bent layer having a bent width of approximately 90 millimeters and a length sufficient to cover the total length of the absorbent center 32, and with an absorbency under load (AUL) of about 6 grams / gram. A second configuration contemplated by this invention for the lower layer 30, is a triple, folded, tissue layer formed of cellulose fibers either coated or uncoated, each layer having a basis weight of P1631 / 98MX approximately 37 grams per square meter, each layer has a density of approximately 0.08 grams per cubic centimeter, with a total weight of approximately 4 grams, with a folded layer having a folded width of approximately 90 millimeters and a sufficient length for cover the total length of the absorbent center 32, and with an absorbency under load (AUL) of approximately 6 grams / gram. A third configuration contemplated by this invention for the lower layer 30 is a single layer formed of air-laid cellulose fibers, with a basis weight of approximately 105 grams per square meter, with a density of approximately 0.08 grams per cubic centimeter, with a width of approximately 90 millimeters, with a total length greater than the total length of the absorbent center 32. When any of the three configurations described above is used, for the lower layer 30, the lower layer 30 has a wet strength of not less than about 0.04 kilonewtons (kN / m) per meter in the transverse direction to the machine or in the direction of the machine. For the purposes of this invention, the wet strength of the lower layer 30 is measured by TAPPI Test Method T 494, "Tensile breaking properties of paper and paperboard (using constant rate of P1631 / 98MX elongation apparatus) "(Properties of paper and cardboard at breaking stress (using a constant speed of an elongation apparatus), and by Test Method TAPPI T 456," Wet tensile breaking strength of paper and paperboard " (Wet strength to paper and cardboard breaking stress.) A fourth configuration contemplated by this invention for the lower layer 30 is a single layer of tissue formed from cellulose fibers with a basis weight of approximately 16 grams per square meter, with a width of about 90 millimeters, and with a total length greater than the total length of the absorbent center 32. Alternatively, a non-woven web of cellulose, synthetic polymer or conjugated synthetic fibers or fibers may be used for the lower layer 30. mixtures of these or an open cell synthetic polymer foam sheet, as long as its absorbency under load (AUL) does not exceed approximately 6 grams / gram The upper layer 28 is applied to the absorbent center 32 but is not attached to the absorbent center 32. The lower layer 30 is adhesively bonded to the absorbent center 32 by a hot melt adhesive, which is preferably applied with two spiral spray nozzles over the total length of the absorbent center 32, with an adhesive addition of about P1631 / 98MX 0.05 milligram per centimeter of the length of the absorbent center 32. The upper layer 28 is bonded with adhesives to the lower layer 30, at the outer edges 48 surrounding the absorbent center 32, preferably with a hot melt adhesive applied in a continuous line. The lower layer 30 is adhesively bonded to the backing sheet 14, along the disposable diaper 10, preferably with a hot melt adhesive applied in solid lines. In Figure 3, the broken lines DI, D2 and D3, respectively represent the regions of the absorbent center 32 that are moistened with the liquid, such as urine, which is transferred through the upper layer 28 to the upper surface 34 of the absorbent center 32. . As suggested by the curved arrows in Figure 3, any liquid permeating the absorbent center 32 is directed through the lower layer 30 towards the lower surface 36 of the absorbent center 32, which is thus wetted again with the liquid transported by the lower layer 30. Since the invention allows the absorbent center 32 to store a liquid, such as urine, with improved efficiency, the absorbent center 32 can have a total length of about 40% to about 80% less than the total length of the lower layer 32, P1631 / 98 X to extend along a front portion of the lower layer 32 and to end at the rear edge 44a indicated by the broken line of Figure 1, without significant reduction in its effective capacity to store a liquid but with reductions concomitant not only in the cost of the diaper but also in the volume of the disposable diaper. In Figure 4, where the reference numbers with supra-indexes are used to indicate the elements that can be similar to the elements with the same reference numbers without supra-indices of Figures 1, 2 and 3, as disposable diaper 10 'in accordance with the previous technology, are illustrated. The disposable diaper 10 'has a top sheet 12' similar to the top sheet 12, a backing sheet 14 'similar to the back sheet 14, and an absorbent structure including a top layer 28' similar to the top layer 28, which includes an absorbent center 32 'similar to the center 32 absorbent, but which does not include the lower layer similar to the lower layer 30. In Figure 4, the broken lines D4, D5 and D6, respectively, represent the regions of the absorbent center 32 'which is moistened with a liquid, such as urine, which is transferred through the upper layer 28 to the upper surface 34' of the center 32 'absorbent. He P1631 / 98MX disposable diaper has no means to conduct the liquid that permeates the absorbent center 32 'to the lower surface 36' of the center 32 'to re-wet the absorbent center 32'. If the disposable diaper 10 'were provided with the lower surface 36' of the absorbent center 32 ', with a lower layer (not shown) with an absorbency under load (AUL) that was substantially more than about 6 grams / gram, the lower layer it would be less effective to re-wet the lower surface 36 'of the absorbent center 32', when compared to the effectiveness of the lower layer 30 of the absorbent center 32 to re-wet the lower surface 36 of the absorbent center 32 in the preferred embodiment. Some modifications can be made in the preferred embodiment without departing from the scope and spirit of the invention.

P1631 / 98MX

Claims (20)

1. NOVELTY OF THE INVENTION Having described the present invention, it is considered as a novelty and, therefore, the content of the following CLAIMS is claimed as property: 1. An absorbent article consisting of a liquid-permeable upper sheet, a sheet of liquid impervious backing and an absorbent structure placed between the upper sheet and the backing sheet, the absorbent structure includes an upper layer near the upper sheet, a lower layer near the back sheet and an absorbent center placed between the sheets. upper and lower layers, the absorbent center has a front end and a rear end, the absorbent center is formed of cellulose fibers and distributed particles of a superabsorbent polymer (SAP) and has a density within the limits of about 0.12 grams per square centimeter to approximately 0.22 grams per square centimeter, the absorbent center has an elongated central portion with an absorbency under load (AUL) not less than about 12 grams / gram, the absorbent center has a top surface facing the top sheet and a bottom surface facing the back sheet, the top layer being formed of selected fibers of P1631 / 98MX polyester, polyolefins, cellulose and conjugated synthetic fibers and mixtures of the same fibers and provides means to absorb some of the liquid permeating the upper layer of the upper sheet and to transfer it towards the upper surface of the absorbent center, the rest of the liquid permeates the upper layer of the upper sheet, the lower layer provides means for transferring the liquid permeating the lower layer from the absorbent center towards the lower surface of the absorbent center, the lower layer having a wet strength not less than approximately 0.04 kilonewtons (kN / m) in the direction transverse to the machine or in the machine direction, the upper and lower layers extend beyond and are joined together to one or both of the front and rear ends of the absorbent center, In order to stabilize the absorbent center, the lower layer has a basis weight no greater than approximately 150 grams per square meter and ne an absorbency under load (AUL) not greater than about 6 grams / gram, the lower layer has a total length and the absorbent center extends along the front portion of the lower layer and has a total length that is approximately 40% to about 80% less than the total length of the lower layer, wherein the absorbent center functions as the main liquid storage layer of the article P1631 / 98MX absorbent. The absorbent article of claim 1, wherein the upper and lower layers of the absorbent structure are joined together at both the front and rear ends of the absorbent center. 3. The absorbent article of claim 1, wherein the absorbent center has a leading end, a trailing end and two fins projecting from the central, elongated portion near the leading end, the superabsorbent polymer (SAP) is present in the upper surface in essentially no concentration and in each of the fins at a concentration of about half the concentration of the superabsorbent polymer (SAP) along the elongated central portion. The absorbent article of claim 1, wherein the bottom layer is formed of cellulose fibers and has a density within the range of about 0.06 grams per cubic centimeter to about 0.12 grams per cubic centimeter. The absorbent article of claim 4, wherein the bottom layer of the absorbent structure is a layer of air-laid pulp having a basis weight of approximately 150 grams per square meter. 6. The absorbent article of the claim P1631 / 98 X 4, wherein the bottom layer of the absorbent structure is a layer of air-laid, triple, folded pulp, each layer having a basis weight of approximately 35 grams per square meter. 7. The absorbent article of the claim 4, wherein the bottom layer of the absorbent structure is a triple, folded, coated tissue layer, each layer having a basis weight of approximately 37 grams per square meter. 8. The absorbent article of the claim 4, wherein the absorbent layer of the absorbent structure is an uncoated, multilayer, pleated layer of tissue, each layer having a basis weight of approximately 37 grams per square meter. 9. The absorbent article of the claim 1, wherein each of the upper and lower layers of the absorbent structure is a layer of tissue having a basis weight of approximately 16 grams per square meter. The absorbent article of claim 1, wherein the bottom layer of the absorbent structure is a nonwoven web made of cellulose fibers, synthetic polymer or synthetic conjugated fibers or mixtures of these fibers. The absorbent article of claim 1, wherein the bottom layer of the absorbent structure P1631 / 98MX is made of an open cell synthetic polymer foam. 12. An absorbent article consisting of a liquid-permeable top sheet, a liquid-impermeable backing sheet and an absorbent structure placed between the top sheet and the backsheet, the absorbent structure includes a top layer near the sheet upper, a lower layer near the backing sheet and an absorbent center positioned between the upper and lower layers, the absorbent center has a front end and a rear end, the absorbent center is formed of cellulose fibers and particles distributed from a superabsorbent polymer (SAP) and has a central portion, elongated, with an absorbency under load (AUL) not less than about 12 grams / gram, the absorbent center has a top surface facing the top sheet and a bottom surface facing the sheet of backing, the upper layer provides means to absorb some of the liquid permeating the upper layer of the upper sheet and for transferring it towards the upper surface of the absorbent center, the rest of the liquid permeates the upper layer of the upper sheet, the lower layer provides means for transferring the liquid permeating the lower layer from the absorbent center towards the lower surface of the absorbent center. P1631 / 98MX absorbent center, the bottom layer has a basis weight no greater than about 150 grams per square meter and has an absorbency under load (AUL) not greater than about 6 grams / gram. 13. The absorbent article of the claim 12, wherein the lower layer has a total length and wherein the absorbent center extends along a front portion of the lower layer and has a total length that is from about 40% to about 80% less than the total length of the lower layer. The absorbent article of claim 12, wherein the bottom layer is formed of cellulose fibers, wherein the absorbent center has a density within the range of about 0.12 grams per cubic centimeter to about 0.22 grams per cubic centimeter, and wherein the lower layer has a density of about 0.06 grams per cubic centimeter to about 0.12 grams per cubic centimeter. 15. The absorbent article of claim 14, wherein to stabilize the absorbent center, the bottom layer has a wet strength of not less than about 0.04 kilonewtons (kN / m) per meter in width in the transverse direction to the machine or in the direction of the machine, and the upper and lower layers extend beyond and are joined together at one or both ends P1631 / 98MX front and rear of the absorbent center. 16. The absorbent article of claim 15, wherein the upper and lower layers of the absorbent structure are bonded together at both the front and rear ends of the absorbent center. 17. The absorbent article of claim 12, wherein the upper and lower layers of the absorbent structure is a layer of tissue having a basis weight of approximately 16 grams per square meter. 18. An absorbent article consisting of a liquid-permeable top sheet, a liquid-impermeable backsheet and an absorbent structure placed between the top sheet and the backsheet, the absorbent structure includes a top layer near the sheet upper, a lower layer near the backing sheet and an absorbent center placed between the upper and lower layers, the absorbent center has a front end and a rear end, the absorbent center is formed of cellulose fibers and particles distributed from a superabsorbent polymer (SAP) and has a central portion, elongated, with an absorbency under load (AUL) not less than about 12 grams / gram, the absorbent center has a top surface facing the top sheet and a bottom surface facing the sheet backup, the layer P1631 / 98MX upper provides means to absorb some of the liquid that permeates the upper layer of the upper sheet and to transfer it towards the upper surface of the absorbent center, the rest of the liquid permeates the upper layer of the upper sheet, the lower layer provides media to transfer the liquid permeating the lower layer from the absorbent center to the lower surface of the absorbent center, the lower layer has a basis weight no greater than approximately 150 grams per square meter and has an absorbency under load (AUL) not greater than approximately 6 grams / gram. 19. The absorbent article of claim 12, wherein the bottom layer has a total length and wherein the absorbent center extends along a front portion of the bottom layer and has a total length that is approximately 40% a approximately 80% smaller than the total length of the lower layer. The absorbent article of claim 12, wherein the bottom layer is formed of cellulose fibers, wherein the absorbent center has a density within the range of about 0.12 grams per cubic centimeter to about 0.22 grams per cubic centimeter, and wherein the lower layer has a density of about 0.06 grams per cubic centimeter to about 0.12 grams per cubic centimeter. P1631 / 98MX