MXPA92006491A - Absorbent article that has insuffled components in state fund - Google Patents

Abstract

The present invention relates to an absorbent article having melt blown components comprising: a liquid pervious top sheet, a back or liquid impervious back sheet bonded to said top sheet, an absorbent core positioned between said top sheet and said back sheet, characterized in the absorbent article comprises a first layer and a second layer, the first layer comprising a web of fibers blown in the melted state, the web of fibers blown in the melted state comprising a plurality of fibers blown in the melted state of microdenier that have pores therebetween, having a first average wet pore radius size without charge, the second layer comprising a material selected from the group consisting of: paper web, a carded nonwoven web, and a non-woven web linked by rotation, and a plurality of particles of superabsorbent matter between said first and second layers a, wherein at least one of said first and second layers has been treated with solvents, and said first and second layers have been held together at least partially by means of said particles of superabsorbent material with heat and pressure bonds; acquisition placed between said upper sheet and said absorbent core, the acquisition layer having pores therein having a second average wet pore radius size without load, wherein said second average wet pore radius size is greater than said first average pore radius size in wet

Description

ABSORBENT ARTICLE OUE HAS COMPONENTS INSUFFLED IN FUSED STATE INVENTORS: JAMES ILLIAM CREE, ROBERT LEE E. MARSHALL, JOHN THOMAS COOPER, BRUCE BROWN, ARIN HELENE COSTEA, JENNIFER LYNN DAVID and JULIAN PLUMLEY, all citizens of the United States, except the last one, of British nationality, domiciled respectively in 1815 Taft Road, Cincinnati, Ohio; 3018 Ramona Avenue, Cincinnati, Ohio; 7333 Tarragon Court, West Chester, Ohio; 3511 Arbor Hill Lane, Maineville, Ohio; 6913 Leedslane, West, Cincinnati, Ohio; 95 Woodfield Court, Racine, Wisconsin, all these in the United States, and Neu iesen eg 1, Satteldorf, Germany.

CAUSAHIENT: THE PROCTER & GAMBLE COMPANY, a partnership of the United States, residing in One Procter & Gamble Plaza, Cincinnati, Ohio, United States.

Summary An absorbent article is provided, such as a diaper, a sanitary napkin, a device for incontinent adults, and the like, having components insufflated in the molten state.

The absorbent articles preferably comprise an upper sheet of thermoplastic film with openings, permeable to liquids, a back sheet or backing impervious to liquids, an absorbent core, and a fibrous web for acquisition of nonwoven fibers linked by rotation. The absorbent core is positioned between the upper sheet and the backsheet, which are joined at least about a portion of the periphery of the absorbent article and the upper sheet is fused to the acquisition pattern at discrete joining points. The acquisition pattern is placed between the upper sheet and the absorbent core. Field of Invention The present invention relates to absorbent articles such as diapers, sanitary napkins, incontinent adult devices and the like, which have components blown in the molten state. BACKGROUND OF THE INVENTION All types and variety of absorbent articles configured for the absorption of bodily fluids such as menstruation, urine and faeces are well known, of course. The absorbent articles typically comprise several layers. These generally include, from top to bottom, a liquid permeable layer, an absorbent layer and a liquid impervious layer. Additional layers can also be interposed between any of these layers. Such additional layers may serve several different purposes. These layers are generally held together around their peripheries by conventional means, such as adhesives, folding, melting and other methods known in the art. Absorbent articles may have, and in many cases preferably have, a liquid impervious bond around their periphery. This will not interfere with the function of the absorbent article. However, it is often also desirable to bond the layers together on their faces. The joining of the faces of these layers presents certain technical problems. This is particularly the case when it is desired to join the upper layers permeable to liquids and the absorbent layers. The same means can not be used to join the layers in their peripheries because they will tend to block the flow of liquids to the absorbent layer. Several attempts have been made to address this problem. These have included using hot melt adhesives, and other non-water based adhesives. Such adhesives will have less tendency to dissolve when they make contact with body fluids. Other attempts have been made to apply adhesives in extremely thin layers or in particular patterns to try to minimize interference with the flow of liquids to underlying layers. U.S. Patent No. 4,573,986, issued to Minetola et al. On March 4, 1986, discloses a preferred way of applying adhesives. Although the application of adhesives in the manner described in the Minetola et al patent works quite well, the search for improved ways of securing the faces of the layers of the absorbent products has continued. The main reason to look for improved ways to secure the faces of such layers is that in many casesadhesives that initially work properly can eventually fail and cause the liquid permeable layer to peel off. This problem is particularly evident during prolonged use of an absorbent article. This problem is often aggravated when the liquid-permeable layer is a plastic film with openings. Although plastic films with openings made in accordance with the patents owned by the ceisonary of the present invention work very well, certain problems can occur when they are separated from their underlying layers. The plastic films are sufficiently thin so that they can move well into the slits of the wearer's body (such as the space between the wearer's hips) when they separate. Due to its plastic composition, in some of these cases the liquid-permeable layer can even stick to the wearer's skin. The adhesives can cause the film to have a sticky surface close to the user's body, which helps cause the liquid-permeable layer to stick to the user's skin.

The separation of the formed film from the absorbent layers often causes the exudates to run to the top of the product along the longitudinal edges. The exudates will not penetrate the film, as there is no longer an underlying absorbent layer in contact with the film so that the exudates are impregnated. This is particularly true in the case of thick pads that have air felt batts for their absorbent cores. The absorbent core of such thick pads tends to collapse and bulge or collect transversely at the center of the product at the first wetting. This recollection, combined with the separation of the formed film, leaves the portion of the pad adjacent to its longitudinal edges without any underlying absorbent material, thereby increasing the possibility of bleeding or leakage at the top of the product along the edges. longitudinal Several patents describe absorbent products having layers held together in alternative forms for several different purposes. Such efforts are described in U.S. Patent Nos. 3,965,906 and 4,184,902, issued to Karami; 4,391,861, assigned to Butterworth et al .; 4,397,644, issued to Matthews and others; 4,475,911, issued to Gellert; 4,726,976, issued to Karami et al .; 4,752,349, issued to Gebel; 4,753,840, issued to Van Gompel; 4,823,783, issued to Willhite, Jr., and others; 4,844,965, granted to Foxman; and 4,908,026, issued to Su iennick and others. Most of these patents, however, do not describe melting a formed film with apertures on a nonwoven material. It is believed that such patents and others are not directed to the use of fusion to create bonding sites that do not interfere with the acquisition of liquids towards the absorbent layer. Thus, there is a need for absorbent articles having a better bond between their layers, particularly between the upper, extreme fluid permeable layers. Therefore, it is an object of the present invention to provide absorbent articles having bond between their layers, particularly the upper, liquid-permeable top layers, which maintain sustained bond even under prolonged use. It is another object of the present invention to provide absorbent articles having liquid permeable layers bonded at bond sites that provide structures that do not interfere with the acquisition of liquids towards the absorbent layer. Yet another object of the present invention is to provide an absorbent article that can be visually observed by the user as having potential to assist in the absorption of liquids. These and other objects of the present invention will be more obvious when considered with reference to the following description and when taken in conjunction with the accompanying drawings. SUMMARY OF THE INVENTION In accordance with the present invention, there is provided an absorbent article, such as a diaper, a sanitary napkin or an incontinent adult device, or the like, having fused layers. The absorbent article preferably comprises a liquid-permeable upper sheet of thermoplastic film with apertures, a back or liquid-impermeable backsheet, bonded to the topsheet, an absorbent core, and an acquisition layer. The absorbent core is placed between the upper sheet and the back or back sheet. The acquisition layer preferably comprises a fibrous web of non-woven fibers linked by rotation. The acquisition layer may be a separate weft positioned between the topsheet and the absorbent core, or may comprise part of the topsheet or part of the core (or other element). The top sheet and the back sheet are joined together along at least a portion of the periphery of the absorbent article. The top sheet and the acquisition layer (or other underlying layer) are placed in face-to-face relationship. The top sheet is secured to such underlying layer (or layers) in bonded areasdiscreet At least some of the linked areas provide structures with drainage passages for the liquids to pass through the absorbent core. The merging of the faces of the upper sheet and the acquisition layer keeps these layers in a bound condition, even under prolonged use. It is believed that the union achieves the aforementioned objectives, among others. It is also believed that the bond creates bonding sites that provide structures that do not interfere with the acquisition of liquids towards the absorbent core. The sustained bond also facilitates the absorption of liquids towards the absorbent core by keeping an underlying absorbent layer in constant contact with the top sheet of film with openings. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a top plan view of a preferred sanitary napkin embodiment of the present invention. Figure 2 is a simplified sectional cross-sectional view taken along line 2-2 of Figure 1. Figure 3 is a cross-sectional view, simplified, similar to that of Figure 2, showing an arrangement alternative of the sanitary towel components. Figures 4-6 are top views in plan and in simplified cross section, along lines 5-5 and 6-6, respectively, of a thick sanitary napkin with a profiled shape. Figures 7 and 7A are simplified schematic views and highly amplified lower floor of a top sheet material comprising a film with openings with interwoven non-woven fibers. Figure 8 is a simplified and highly amplified cross-sectional view of a binding site where the topsheet of the sanitary napkin is fused to an underlying acquisition fibrous layer. Figure 8A is a schematic side view of part of a device that can be used to create a link by fusion. Figures 9 and 10 are highly amplified upper and lower plan views of photographs of the fused layers in the area of typical bonding sites. Figures 11 and 12 are simplified schematic views showing the difference between the arrangement of the top sheet when relatively deep and relatively shallow links are used. Figure 13A is a plan view of a sanitary napkin provided with an alternative link pattern. Figures 13B-13D are top and bottom plan views and a perspective view photograph of a sanitary napkin provided with another alternative link pattern. Fig. 14 is a photograph showing a cross-sectional view of an embodiment in which the underlying fibrous layer has been stretched before melting it with the film with openings. Figure 15 is an exploded view in perspective showing the assembly of a sanitary napkin containing a preferred absorbent core and panty fastening adhesive for use in the present invention. Figure 16 is an edge view of an alternative top sheet comprising a nonwoven material and a formed film. Figure 17 is a perspective view of an alternative link structure. Figure 18 is a simplified schematic view of a process that can be used to make the top sheet shown in Figures 7 and 7A. Figure 19 is a perspective view of the formed film supplied to the process shown in Figure 18. Figure 20 is a graph that outlines a "bi-modal" pore size distribution. Figure 21 is a schematic drawing comparing the small-sized pores present in the melt-blown absorbent core materials described herein with the pore size of a conventional fabric placed in air. Figure 22 is a graph comparing the size of the wet pore radii of an unburned molten core with that of the same core material under a load of 0.25. psi. Figure 23 is an enlarged schematic view of a portion of an absorbent core comprising particles of fiber-filled superabsorbent material encapsulated within blown-in-melt-state plots. Figure 24 is a schematic view of an apparatus and a process for making a combined absorbent structure using particles of superabsorbent material as a primary or secondary binder to join together two or more wefts. Figure 25 is a schematic view of a preferred multilayer combined, made with the process shown in Figure 24. Figure 26 is a melt blown acquisition layer having a bimodal pore size distribution. Figure 27 is a schematic drawing of an apparatus for conducting the liquid extrusion analysis process. Detailed Description of the Preferred Embodiments 1. Introduction The present invention relates to absorbent articles such as diapers, sanitary napkins, incontinent adult devices and the like, which have fused layers. The term "absorbent article," as used herein, refers to articles that absorb and contain body exudates. More specifically, the term refers to articles that are placed against or in proximity to the user's body to absorb and contain various exudates discharged from the body. The term "absorbent article" is intended to include diapers, sanitary napkins, linings for panties and incontinence pads, and the like. The term "disposable" refers to articles that are intended to be discarded after a single use and preferably recycled, composted or otherwise disposed of in an environmentally compatible manner. (That is, they are not intended to be washed or otherwise restored or reused as an absorbent article.) In the preferred embodiment illustrated, the absorbent article is a designated sanitary napkin 20. The term "sanitary napkin", as used herein, refers to an article that is used by women adjacent to the pudendal region, which is intended to absorb and contain the various exudates that are discharged from the body (eg, blood, menstruation and urine). However, the present invention is not limited to the particular types or configurations of absorbent articles shown in the drawings. The sanitary napkin 20 has two surfaces, a surface that makes contact with the body or "body surface" 20a and a garment surface 20b. The sanitary towel 20 is shown in Figure 1 seen from its body surface 20a. The body surface 20a is intended to be used adjacent to the wearer's body. The garment surface 20b of the sanitary napkin 20 (shown in Figure 2) is on the opposite side and is intended to be placed adjacent to the wearer's undergarments when the sanitary napkin 20 is used. The sanitary napkin 20 has two central lines, a longitudinal center line 1 and a transverse center line t. The term "longitudinal", as used herein, refers to a line, axis or direction in the plane of the sanitary napkin 20 that is generally aligned with (eg, approximately parallel to) a vertical plane that bisects a wearer stop in left and right body halves when the sanitary napkin 20 is used. The terms "transverse" or "lateral", as used herein, are interchangeable, and refer to a line, axis or direction that lies within the of the sanitary napkin 20 which is generally perpendicular to the longitudinal direction. Figure 1 shows that the sanitary napkin 20 also has two spaced apart longitudinal or lateral edges 22 and two spaced apart transverse or end edges (or "ends") 24, which together form the periphery 26 of the sanitary napkin 20. The sanitary napkin 20 It can be of any thickness, including relatively thick or relatively thin. The embodiment of the sanitary napkin 20 shown in Figures 1-3 of the drawings is intended to be an example of a relatively thin sanitary napkin. However, it should be understood that upon seeing these figures, the number of layers of material shown makes the sanitary napkin 20 appear to be thicker than it actually is. A sanitary towel 20"thin" preferably has a gauge of less than about 3 mm. The thin sanitary towel 20 shown should also preferably be relatively flexible, so that it is comfortable for the user. Figure 2 shows the individual components of the sanitary napkin. The sanitary napkin 20 of the present invention generally comprises at least three primary components. These include a liquid pervious topsheet 28, a backsheet or liquid impervious backing 30 (or "barrier means"), and an absorbent core 32. The absorbent core 32 is positioned between the topsheet 28 and the backing sheet. backsheet 30. The sanitary napkin 20 also comprises a liquid permeable acquisition layer (or acquisition sheet) 34. The acquisition layer 34 may be a separate element positioned between the topsheet 28 and the absorbent core 32, or may comprising part of the topsheet 28 or part of the core 32. The sanitary napkin 20 preferably also includes side wings or "wings" 36 that are folded around the crotch portion of the wearer's panties. The sanitary napkin 20 shown also has adhesive fastening means 38 for attaching the sanitary napkin 20 to the wearer's undergarments. Removable release lining 40 covers the adhesive attachment means 38 to prevent the adhesive from sticking to a surface other than the crotch portion of the underwear prior to use. 2. Individual Components of the Absorbent Article The individual components of the sanitary napkin 20 will now be seen in greater detail. A. The Top Sheet The top sheet 28 comprises a first liquid permeable component. When the sanitary napkin 20 is in use, the topsheet 28 is in close proximity to the wearer's skin. The topsheet 28 is preferably as deformable, soft to the touch and non-irritating to the wearer's skin as possible. The topsheet 28 must also exhibit good impact and a reduced tendency to rewet, allowing the bodily discharges to penetrate rapidly and flow to the core 32, but not allowing such discharges to flow back through the topsheet 28 to the skin. of the user. The topsheet 28 has two sides (or faces or surfaces), including a side facing the body 28a and a side facing the garment (or side facing the core) 28b. The body facing side 28a of the topsheet 28 generally forms at least a portion of the contacting surface with the body ("body surface") 20a of the sanitary napkin 20. The topsheet 28 has two longitudinal edges 28c and two end edges 28d. (A similar number of systems will be used for the other components of the sanitary napkin, that is, the side of the component that looks at the wearer's body will be designated by the component number and the letter "a". The wearer's undergarments will be designated by the component number and the letter "B." The side and end edges will be designated by the component number and the letters "c" and "d", respectively.) A top sheet Suitable may be manufactured from a wide range of materials, including, but not limited to, woven and non-woven materials, formed thermoplastic films, apertures, apertured plastic films, hydroformed films, porous foams, cross-linked foams, crosslinked thermoplastic films, and meshes thermoplastic Suitable woven and nonwoven materials may comprise natural fibers (e.g., wood or cotton fibers), synthetic fibers (e.g., polymer fibers, such as polyester, polypropylene, polyethylene or polyvinyl alcohol, resins based of starch, polyurethanes, cellulose esters, nylon and rayon fibers) or a combination of natural and synthetic fibers. Films formed with apertures are generally preferred for the topsheet 28 because they are permeable to liquids and, if they have proper apertures, have a reduced tendency to allow liquids to pass back and re-wet the wearer's skin. Figure 1 shows that the upper sheet 28 of formed film is provided with a multiplicity of apertures 29. The openings 29 are shown only in portions of the upper sheet 28 that cover the fins 36 for illustration clarity of the fusion bonds 44. Nevertheless, it will be undeod that the openings 29 will ordinarily be distributed at least over the main body portion (or "central absorbent pad") 21 of the sanitary napkin 20. The topsheet 28 preferably has a gauge of between about 0.001-0.002 in. (0.025-0.05 mm) before any opening formation. The top sheet 28 preferably has a larger gauge (between about 0.02 to 0.03 in) after the formation of openings. This is due to the formation of the tapered capillary structures (shown in Figure 7) created when the top sheet is formed according to several of the processes described herein. Suitable formed films are described in U.S. Patent Nos. 3,929,135, issued to Thompson on December 30, 1975; 4,324,426, issued to Mullane et al. On April 13, 1982; 4,342,314, issued to Radel et al. On August 3, 1982; 4,463,045, issued to Ahr et al. On July 31, 1984; and 5,006,394, issued to Baird on April 9, 1991. Suitable additional, shaped and hydroformed films are described in US Pat. Nos. 4,609,518; 4,629,643; 4,695,422; 4,772,444; 4,778,644; and 4,839,216, from the United States, granted to Curro and others; 4,637,819, granted to Ouellette et al. In another embodiment, the topsheet 28 comprises a nonwoven material 25 and a plastic film 27 shown in Figure 16 and described in greater detail in U.S. Patent Application Serial No. 07 / 794,745, filed by Aziz et al. On November 19, 1991. Still other materials suitable for use as a topsheet are described in U.S. Patent Nos. 4,775,579, Hagy et al., Issued October 4, 1988, 5,023,124, issued to Kobayashi on June 11, 1991, and in the European patent application 0 304 617 A2, published on March 1, 1989, in the name of Suda and others. In a particularly preferred embodiment, the topsheet 28 comprises a film of interlaced fibers. The term "interlaced fiber film" refers to films with apertures having interlaced fibers in and around their apertures. The film with apertures of such a top sheet may comprise any of the films or meshes described above. The film has nonwoven fibers intertwined loosely, mechanically or thermomechanically, with it. The fibers are preferably intertwined along or from the direction of the side facing the core 28b. Figure 7 shows an example of such a top sheet material interlaced with fibers. Figure 7 shows an upper sheet 28 created by joining hydrophilic (or hydrophobic) fibers 42 'to a film with openings. The fibers 42 'used can be of any type of polyolefin. The fibers 42 'can be used in conjunction with the acquisition layer 34, or to replace the acquisition layer 34. The primary objective of interlacing the fibers is to drain any surface fluids from the plastic film. More specifically, the interlaced fibers 42 'are in much closer contact with the lower opening 29b of the openings 29 than is possible by simply placing nonwoven material adjacent to the film. This close contact prevents any free spaces from forming between the nonwoven material and the film in the lower opening 29b. The removal of the clearances allows the fibers 42 'to drain liquids through the film 27 and prevent a meniscus from forming in the lower opening 29b. Otherwise, liquids can get stuck in this place and then re-moisturize the user's skin. The fibers can be mechanically or thermomechanically interlaced with the film by means of any suitable process. For example, the fibers can be blown in the melted state onto the film, twisted on the film, carded on the film, thermomechanically interlaced with the film such as filling or blowing in the melted state on the plastic film while it is still in the state melted, or hydro-entangled with the film. The preferred method for joining the fibers to the film is via a process that uses either air attenuation or mechanical correction combined with placement in air. Figure 18 shows a preferred way of obtaining such a top sheet structure. In this case, a polymeric, thermoplastic, synthetic, hydrophilic material is extruded in the form of a fiber. The fibers are subjected to attenuation by directing a stream of air over the fibers once they exit the die 102. This process is known as a melt-blown process and is described in U.S. Patent No. 3,978,185, assigned to US Pat. Exxon, granted to Buntin and others. Suitable hydrophilic fibers can be formed of intrinsically wettable fibers such as nylon copolymers comprising a nylon component and a hydrophilizing component. Such material is commercially available from Allied Signal Inc., under the name Hydrofil SCFX. The side facing the core 27b of the film 27 should look at the head of the die 102 of blowing in the melted state. The film 27 preferably has a multiplicity of cone-like projections (or "cones") 23 that define tapered capillaries. The process of making this type of film 27 can form cones 23 having external surfaces that form jagged or jagged edges. A film with apertures 27 particularly suitable is described in United States Patent No. 4, 463,045 and rolled with ring as described below to provide a degree of extension capacity. The fibers 42 'are ejected from the die 102 and attached to the side facing the core 27b of the plastic film 27. The melted fibers 42' and the cones 23 of the film 27 tend to melt and melt. This causes the fibers 42 'to be permanently attached to the film, as shown in Figure 7A. It is believed that the bonding occurs mainly between the partially melted fibers 42 'and the partially indented edges formed on the outer surfaces of the cones 23 that form the capillaries of the apertured film 27. In another preferred embodiment, the fibers 42' they are of a thermoplastic, synthetic, but not hydrophobic nature. Hydrophobic fibers such as polyethylene fibers are available from The Dow Chemical Company, under the trade designation Aspun, or as polypropylene fibers from Exxon Corporation under the designation Escorene, series 3,400 and 3,500. Once formed, the entire screen is treated by any known methods (described below in greater detail) to make it hydrophilic. Such a process will allow openings to better handle fluids. It is also possible to roll with the whole frame after these treatment processes. The material of the upper sheet 28 interlaced with fibers provides more intimate contact between the film with openings 27 and the nonwoven fibers 42 '. This can create advantages of improved liquid transport through the film to the fibers 42 'and the underlying layers, such as the absorbent core 32 or the acquisition layer 34. It can also provide improved comfort as the film 27 will have less tendency to separate from the underlying interlaced fibers 42 '. This will prevent the top sheet 28 from moving towards the slits of the wearer's body. In still another preferred embodiment (shown in Figure 15), the sanitary napkin 20 comprises components that are extensible (i.e., capable of stretching, particularly in the longitudinal direction) when the sanitary napkin is used. Preferably, the sanitary napkin 20 is capable of elongating between about 15 and about 40% of its undrawn length. This extension capacity provides better fit in use, attachment to the wearer's undergarments, comfort and reduced staining. In other embodiments, only limited portions of the components of the sanitary napkin 20 need to be capable of stretching. A type of top sheet 28 for use in the embodiment shown in Figure 14 can be made in accordance with US Patent No. 4,463,045 and rolled with a ring to provide it with some longitudinal extension capacity. Suitable processes for ring rolling or "pre-corrugated" are described in U.S. Patent Nos. 4,107,364, issued to Sisson on August 15, 1978; 4,834,741, granted to Sabee on May 30, 1989, and in the pending United States patent applications, assigned to the same assignee as the present one, Nos. Of Series 07 / 662,536, filed by Gerald M. Weber and others, 07 / 662,537, filed by Kenneth B. Buell et al., And 07 / 662,543, filed by Gerald M. Weber and others, all filed on February 28, 1991. The fold lines in the corrugations of the top sheet should run in the transverse direction so that the top sheet is longitudinally extensible. Such topsheet is described in greater detail in the following U.S. patent applications, filed June 23, 1991: U.S. Nos. 07 / 734,404, filed in the name of Thompson et al .; 07 / 734,392, filed in the name of Thompson and others; and 07 / 734,405, presented in the name of Buenger et al. These last three patent applications can be collectively referred to as patent applications of "capillary channel fibers". Further, in the preferred embodiments of the present invention, at least a portion of the topsheet 28 is treated with a surfactant. This can be accomplished by any of the common techniques well known to those skilled in the art. Suitable methods for treating the topsheet with a surfactant are described in various antecedents, including U.S. Patent Nos. 4,950,264 and 5,009,653, issued to Osborn, and in U.S. Patent Application Serial No. 07 / 794,745. , filed by Aziz et al. on November 19, 1991. The last patent application teaches treating the film component with openings of a nonwoven fabric upper sheet / thermoplastic film formed with apertures, with a surfactant. The surfactant is preferably incorporated into the resin used to make the formed thermoplastic film. Treating the top sheet 28 with a surfactant renders the surface of the top sheet 28 more hydrophilic. This results in the liquid penetrating the upper sheet 28 faster than if the surface was not treated. This reduces the possibility of body fluids leaking out of the top sheet 28 instead of being drained through the top sheet 28. B. The Acquisition Layer The acquisition layer (or "acquisition / distribution layer"), or "acquisition sheet") 34 is shown in Figure 2. It is placed between the topsheet 28 and (at least a portion of) the absorbent core 32. In the embodiment shown in Figure 2, the acquisition layer 34 It is a folded sheet of nonwoven material. However, it should be understood that the acquisition layer 34 need not be a folded sheet. The terms "layer" or "weft", as used herein, include, but are not limited to single unfolded sheets, folded sheets, strips of material, loose or bonded fibers, multiple layers or laminates of material, or other combinations of such materials. These two terms, in this way, are not limited to simple layers or unfolded sheets of material. In Figure 2, the acquisition layer 34 is a "double" Z-folded sheet. The sheet 34 is folded more specifically so that when the sanitary napkin is cut along the transverse line, the left half of the folded sheet appears as an inverted "Z" in cross section, and the right half appears as a " Z ". The sheet 34 is preferably folded so that it has an upper portion 54 that appears as a rectangular strip in plan view. The upper portion 54 of the acquisition layer 34 is preferably about 227 mm long, and between about 25 and about 38 mm wide. The upper portion 54 preferably has a caliper of about 0.5 to about 4 mm (the upper end of this range creates thicker products). Such a bent array is described in greater detail in U.S. Patent Application Serial No. 07/605, 583, filed on October 29, 1990, in the name of Visscher and others. Figure 3 is a simplified cross-sectional view similar to Figure 2, showing an alternative arrangement of the components of the sanitary napkin 20. In Figure 3, instead of being a separate layer that is located on the core 32, the acquisition layer 34 is an integral layer (or component) comprising the top layer of a laminated absorbent core structure 32. In still other alternative embodiments, the acquisition layer 34 may be omitted altogether. In embodiments without an acquisition layer 34, the absorbent core 32 must comprise at least some types of fibers (preferably synthetic fibers) to which the upper sheet 28 can melt. A sufficient amount of these fibers is preferably located near of the surface facing the body 32a of the absorbent core 32 to facilitate fusion. It is possible to create a bond with natural fibers, such as cellulose, by melting a top sheet of film around the cellulose fibers. However, better bonds with synthetic fibers are typically formed. The cellulose fibers are rather short. When the fusion bonds are spaced apart, some cellulose fibers may be unbound or only bound in one place. This can result in these fibers being released from the bonded structure. Synthetic fibers can be made longer than cellulose fibers. The topsheet 28 is generally described herein as being fused to the acquisition layer 34. This has been done for simplicity of the description. (It is easier to discuss a preferred embodiment than to describe simultaneously all possible embodiments.) Top sheet 28 may be fused directly (or indirectly) to (one or more of) the other underlying components. In its broadest sense, the top sheet 28 comprises a first component that is fused to a second underlying component. Alternatively, the second component may be part of another component, such as part of the top sheet, part of the core, or part of some other component. Thus, for example, it will be understood that in embodiments where the acquisition layer 34 is an integral layer of the core 32 (such as that shown in Figure 3) or is omitted altogether, the upper sheet 28 may be considered as fused to part of the absorbent core 32. The function of the acquisition layer 34 is generally described with respect to the absorbent core 32. It will be understood that in embodiments in which the acquisition layer 34 comprises part of the core 32, the layer acquisition 34 will work to a large extent in the same way. However, it will work in the same way with respect to the remaining portions of the core 32 (rather than the core itself). The improved impregnation also allows the sanitary napkin 20 of the present invention to be made relatively thin. The acquisition layer 34 is capable of dispersing exudates over a large surface area of the absorbent core 32. The acquisition layer 34 in this manner allows the sanitary napkin 20 to absorb relatively large amounts of exudates. The bulky sanitary napkins of the prior art were based on a high degree of vertical absorption at the point where exudates are initially deposited. Because the absorbent cores of these previous towels were quite thick, they could absorb a large volume of exudates, using only a small degree of absorption capacity of surface or lateral area. The sanitary napkins 20 of the present invention will be able to absorb relatively large amounts of exudates because the impregnation disperses the exudates over a large surface area of the absorbent core 32 where the exudates can be absorbed vertically better and more rapidly towards the absorbent core 32. The acquisition layer 34 may have sufficient open spaces between its fibers to provide a fairly high degree of temporary liquid retention capacity. The temporary holding capacity is useful during the time interval between the moment the exudates are deposited on the topsheet 28 and the moment they are absorbed by the absorbent core 32. This is particularly useful in diapers and incontinent articles. This allows the acquisition layer 34 to temporarily acquire and retain fluid torrents (such as urine) in cases where the core 32 absorbs liquids at a lower velocity than that in which they are deposited on the absorbent article. The acquisition layer 34 may also be used to direct exudates towards the ends of the core 32d. The liquid exudates that are deposited on the core 32 will tend to be distributed radially outward from the place where they are deposited. As the core 32 of the sanitary napkin 20 is relatively narrow compared to its length, the liquid exudates will reach the longitudinal edges 32c of the core 32 much sooner than the ends 32d of the absorbent core. The acquisition layer 34 can be used to longitudinally impregnate and direct the exudates towards the ends 32d of the core 32. This more effectively utilizes the core capacity, and reduces the possibility of leakage caused by exudates that prematurely reach the longitudinal edges 32c of the core. . The impregnation referred to herein (unless otherwise indicated) may encompass the transport of liquids in both the "X-Y" and "Z" directions. These directions are shown in Figures 1 and 2. The acquisition layer 34 preferably carries liquids well in both directions. Ideally, liquids are transported in a pyramidal pattern of distribution (or perhaps more accurately, a conical distribution pattern). The apex of the pyramid (or cone) is the point where the liquid is deposited on the surface facing the body 34a of the acquisition layer 34. The liquids are then distributed downward and outward to the base of the pyramid (or cone). In a preferred embodiment, the liquids are distributed to the core 32 by a cascade action. This type of distribution is described in greater detail in U.S. Patent Applications Nos. 07 / 637,090 and 07/637, 571, m filed by Noel and others and by Feist et al. It can be thought of as analogous to filling a tray of ice with water. The liquids are distributed so that after a section of the core 32 reaches its capacity, the liquids then flow laterally downwardly to fill adjacent sections of the core 32. The combination of the acquisition layer 34 and the topsheet 28 also provides a the sanitary napkin, the improved torrent acquisition and the improved cleaning acquisition described in greater detail in U.S. Patent Nos. 4,950,264 and 5,009,653, issued to Osborn. (In this way, the acquisition layer 34 may be referred to as a "cleaning acquisition sheet"). The characteristics of the acquisition layer 34 are as follows. The acquisition layer 34 must be permeable to liquids. The acquisition layer 34 is also preferably deformable, soft to the touch and non-irritating to the wearer's skin. It can be made of any materials capable of dispersing exudates, as described above. The materials are preferably also capable of having the top sheet 28 fused thereto. The acquisition layer 34 may also be provided with stretching properties. The acquisition layer 34 has a face facing the body (or side) 34a, and a face facing the garment 34b. The acquisition layer 34 must be hydrophilic. The fibers or filaments 42 comprising the acquisition layer 34 may be inherently hydrophilic. Alternatively, they can be treated to make them hydrophilic. Suitable methods for converting the fibers into hydrophilic include treating them with a surfactant. The fibers can be treated by spraying the material comprising the acquisition layer with a surfactant or immersing the material in the surfactant. A more detailed discussion of such treatment and hydrophilicity is contained in U.S. Patent Nos. 4,988,344 and 4,988,345, issued to Reising et al. And Reising, respectively. The hydrophilicity of these fibers allows the acquisition layer 34 to aspirate the liquid exudates through the topsheet 28 from below. The acquisition layer 34 may comprise woven or nonwoven materials. These materials can be synthetic, or partially synthetic and partially natural. Suitable synthetic fibers include polyester, polypropylene, polyethylene, nylon, viscose rayon, or cellulose acetate fibers, with polyester fibers being preferred. Suitable natural fibers include cotton, cellulose or other natural fibers.

The acquisition layer 34 may also at least partially comprise crosslinked cellulose fibers. Suitable cross-linked cellulose fibers are described in U.S. Patent Nos. 4,888,093, issued December 19, 1989 to Cook et al .; 4,822,543, issued April 18, 1989 to Dean and others; 4,889,595, issued December 26, 1989 to Schoggen et al .; 4,898,642, issued February 6, 1990 to Moore et al .; and 4,935,022, issued June 19, 1990 to Lash et al. The amount of such natural or modified fibers, however, should not be so great that the topsheet 28 can not be adequately fused to the remaining synthetic fibers. The acquisition layer 34 may also comprise fibers of capillary channels (i.e., fibers having channels formed therein, preferably on their outer surfaces). Such fibers are described in greater detail in the European patent application 0 391814, published October 10, 1990, and in the patent applications of the capillary channel fibers. The acquisition layer 34 may also comprise combinations of the above materials, such as combinations of fibers similar to those described below for use in the absorbent core, or any equivalent material or combinations of materials. The material comprising the acquisition layer 34 may have melting temperatures in different embodiments that are less than, equal to or greater than that of the upper sheet 28. Polyester fibers are preferred because they have a high melting temperature (between about 375 and about 400 ° F). This quality makes them especially suitable for link processing by rotation. Twist link processing uses a high temperature drying process. The polyester fibers are able to go through the bonding process by twisting without being damaged. The use of polyester fibers also has the advantage that such fibers are particularly suitable for use with the preferred types of top sheet materials. The polyester fibers will not melt at the typical melting temperature of the topsheet 28 when it is melted to the acquisition layer 34. This has the advantage that the fibers 42 will remain in their fibrous form after melting. If the top sheet 28 comprises a film formed of polyethylene, for example, it may have a melting temperature in the range of between about 165 and about 215 ° F. The present invention, in this way, advantageously uses materials with dissimilar melting temperatures (as described below) to create structures that improve acquisition through such layers after they are melted. The fibers or filaments 42 comprising the acquisition layer 34 can be of any length, of quality length to continuous filaments. The length of the fibers 42 is preferably between about 1 and about 3 inches (between about 2.5 and about 7.5 cm), and most preferably is about 1.5 inches (about 3.8 cm). The fibers 42 preferably have one denier per filament of between about 1 and about 3, preferably about 1.5. The fibers 42 of the acquisition layer 34 are preferably oriented mainly in a single direction. Typically, the acquisition layer 34 can be manufactured with its fibers oriented in the machine direction (MD). The acquisition layer 34 can be placed on the product with most of the fibers 42 oriented in the longitudinal direction. (That is, the fibers 42 are generally parallel to the longitudinal centerline 1 of the sanitary napkin 20.) The phrase "generally parallel" to the longitudinal centerline (and similar phrases), as used herein, is intended to include fibers that are angled away from the longitudinal center line. These fibers are considered to be generally parallel insofar as they are oriented more in the longitudinal direction than in the transverse direction. The orientation of the fibers 42 of the acquisition layer 34 causes the liquid exudates deposited in the acquisition layer 34 to be preferentially impregnated and distributed to the ends 32d of the absorbent core 32. The acquisition layer 34 can be of any suitable size . The acquisition layer 34 does not need to extend the entire width of the absorbent core 32. For example, the acquisition layer 34 may be in the form of a strip similarly placed (and of a similar size) to the upper portion 54 of the Z-folded sheet shown in Figures 1 and 2. The acquisition layer 34, if it is non-woven, it can be done by several different processes. These include, but are not limited to the following, in order of preference, from least to most preferred: blown in melted state, link by turn, carding, the latter including, in order of preference, thermally bonded, bound by air transverse, linked with dust, bound with latex, bound with solvents, or with the greater preference link by rotation. The processes of link by turn are the most preferred because it is easier to orient the fibers in a single direction in such processes. Commercially available products for use as acquisition layer 34 include a 70/30% rayon / polyester fabric known as Sontara. The Sontara fabric is described in greater detail in U.S. Patent Nos. 4,950,264 and 5,009,653, issued to Osborn. In a particularly preferred embodiment, the acquisition layer 34 comprises a spin-linked nonwoven web composed of permanently wettable fibers. Preferably, the acquisition layer 34 is a spin-linked nonwoven web of 30 g / yd2 (35 g / m2) of polyethylene terephthalate (or PET). Spunbonded fabrics of this type are manufactured by Veratec Company, of Walpole, Massachusetts, United States. The nonwoven web linked by twist is formed such that most of the fibers are oriented in a single direction. The fibers of this particularly preferred acquisition layer material 34 are made of a PET resin and are coated with a permanently wettable, patented finish known as Celwet. These fibers are available from Hoechst Celanese Corporation, of Charlotte, North Carolina, United States. The term "permanently wettable", as used herein, refers to fibers that will sink in less than or about 7 seconds when tested in accordance with basket sink method ASTM D 1117-74. The Celwet finish is particularly preferred for use in sanitary napkins having an upper sheet 28 having a film or mesh with openings with hydro-interlaced nonwoven fibers because the fibers coated therewith will remain extremely hydrophilic after hydroentanglement processes , and therefore are impregnated with blood very well. (1) Fusion of the Top Sheet to the Acquisition Layer The top sheet 28 is secured in contact with an underlying layer. The underlying layer must have some absorption capacity, or be capable of transporting liquids to a layer with absorbent capacity. In the preferred embodiment shown in Figure 2, this is the acquisition layer 34. This relationship results in the upper sheet 28 being penetrated more quickly. In conventional products, the topsheet 28 is initially maintained in contact with the underlying layer by applying adhesive between the underlying layer and the topsheet 28. In the present invention, the topsheet 28 is preferably bonded in face-to-face relationship with the web. underlying acquisition layer 34 by fusion bonding of the topsheet 28 and the acquisition layer 34. The merging of the faces of the topsheet 28 and the acquisition layer 34 of interest to the present invention is located in those portions of the respective faces that are inward of any liquid impervious seam, such as around the periphery 26 of the sanitary napkin 20. (The term "inward" means toward the intersection of the longitudinal and transverse center lines.) The term " "fusion bond", as used herein, is intended to include, but is not limited to (1) true merger, in which both molten materials s are melted together, as well as (2) joints in which a first material is melted and this causes the first material to join the second material not melted by mechanical union.

The upper sheet 28 and the acquisition layer 34 can be completely secured by means of fusion bonding, or partially by fusion bonding and partially by other types of bonding means. Fusion can be achieved by means of heat and / or pressure bonds, ultrasonic bonds, dynamic mechanical links, and the like. Pressure can be applied in any suitable manner, such as by moving the two components between counter-rotating rollers, placing the materials on an anvil and forcing a platen down onto the materials, applying vacuum pressure, and the like. Suitable means that can be adapted for use in melting the top sheet 28 to the acquisition layer 34 are described in at least some of the following United States patents: Nos. 4,430,148, issued to Schaeffer; 4,515,595, issued to Kievit et al .; 4,531,999, issued to Persson et al .; 4,710,189 and 4,808,252, granted to Lash; 4,823,783, issued to Willhite, Jr. and others; and 4,854,984 and 4,919,756, assigned to Ball and others. The two bonded layers, the topsheet 28 and the underlying acquisition layer 34, preferably should exhibit an average shedding strength of more than or about 50 g / in, more preferably greater than or about 65 g / in. in, measured in a sample of 1 x 6 in (2.5 x 15 cm). These values are obtained by measurements made in accordance with the resistance test of the 180 ° detachment bond, described in section 4 below, entitled "Test Methods". However, it should be recognized that these are preferred values. It can make embodiments in which lower link strengths can be used (eg, if the acquisition layer 34 is also partially mechanically interlaced with the top sheet 28). The fusion link preferably comprises a pattern of individual fusion links 44. The individual links 44 can be in any way in plan view. For example, links 44 may be in the form of straight lines or curves, geometric shapes such as circles, squares, rectangles, diamonds and the like, or irregular shapes. The links 44 can be arranged in many different ways. Figure 1 shows a particularly preferred binding pattern. The fusion links 44 comprise discrete joining points comprising circular links. The links 44 are arranged in a pattern that is preferably distributed over the entire body surface 20a of the sanitary napkin, minus the fins. (This is the portion of the sanitary napkin previously referred to as the "main body portion" 21). The link pattern shown in Figure 1 comprises a plurality of larger links 44a and a plurality of minor links 44b. The large links 44a are positioned in the longitudinal central region 46 of the sanitary napkin. The minor bonds 44b are placed in the longitudinal side regions 48 of the sanitary napkin. In Figures 1 and 2, the large links 44a have a diameter of about 2 mm. The large links 44a preferably form a bonded area of about 4 mm2. The small links 44b have a diameter of about 0.5 mm. The small links 44b preferably form a linked area of about 0.25 mm2. The diameter of the bonds 44 in this bonding pattern can vary from about 0.5 to about 3 mm. The diameter of the bonds 44 preferably ranges from about 0.5 to about 2 mm. The links 44 are typically larger than the openings 29 in the upper sheet 28. The links 44 form linked areas 52 (which are described in greater detail below in conjunction with Figure 8) which preferably have a range of depths between about 0.5 and about 1.5 mm, and most preferably between about 1 and about 1.5 mm. (In this way, in the case of acquisition layer 34 bent in Z, the large links 44a penetrate the upper sheet and only part of the gauge of the upper portion 54 of the folded sheet forming the acquisition layer 34. The links 44 are preferably in the form of a plurality of diagonal spaced lines. The lines of the preferred bond pattern shown run in the same direction in the longitudinal center region 46 and the longitudinal side regions 48. The links 44 are preferably spaced between about 5 and about 16 mm, more preferably between about of 5 and about 8 mm. This spacing is measured in the direction of the shortest distance between the links. The large links 44a are preferably distributed in a density of 18 bonds per square inch. The small links 44b are preferably distributed at a density of 25 bonds per square inch. However, it should be understood that the link pattern shown is a preferred pattern, and that many other patterns are also suitable. The links 44 are typically spaced apart from the openings 29 in the upper sheet 28. In this way, the links 44 will occasionally be formed on one or more openings 29, or portions of the openings 29. There is no need to attempt to align the links 44. and the openings 29, however, because the links 44 do not interfere with the flow of exudates to the underlying layers. The strength of the individual links 44 determines the strength of the bond between the layers. Typically, the strength of the link is related to the area of the link (i.e., the larger area of the individual link 44, the stronger the link). A plurality of weaker links spaced closely together can provide a large total linked area. However, the bonded layers will typically be separated by applying the relatively low release force required to separate each weaker bond. Also, if the links are too close together, the effect of the bond will be closer to the one created when adhesives are used and a stiffer product will result. The present invention has the advantage that larger and generally more resistant bonds can be used without interfering with the acquisition of liquids. It is believed that the present invention overcomes the limitations that prevented effective use of larger links. This aspect of the invention thus avoids the undesirable problems caused by using small links spaced very close. Figure 8 is an approximation of a schematic side view of a link site. The link site shown is a highly amplified schematic view of the link 44a shown to the left of the longitudinal centerline 1 in Figure 3. The fusion of the upper film sheet 28 to the fibers 42 of the acquisition layer 34, as noted before, leaves the fibers 42 intact. Figures 9 and 10 show this characteristic. The binding site comprises a fused area (or linked area) where the topsheet 28 is fused to the fibers 42 of the acquisition layer 34. The regions of the topsheet 28 and the acquisition layer 34 surrounding the site of link define a link opening 52 (an opening formed by the link). The link opening 52, because it is within the range of depths specified above, penetrates the topsheet 28 and a portion of the gauge of the acquisition layer 34.

As illustrated in FIG. 8, when the faces of the upper sheet 28 and the underlying layer are described herein as fused, it will be understood that this refers to the overall relationship between these components. The components can be considered to be held together on their faces even when the links 44, feasibly, can penetrate the face of the underlying layer in the interface between the topsheet 28 and the underlying layer. The link forms a sump or reservoir structure which is bounded on the bottom by the melted area 50. In Figure 8, the sides 56 of the reservoir are formed partly by portions of the upper sheet of film 28 and partly by portions of the layer. acquisition 34. The acquisition layer 34 comprises a plurality of fibers 42 with a plurality of open spaces (or hollow spaces) 58, between the fibers 42. The open spaces and the hydrophilic fibers of the acquisition layer 34, in this way , provide a plurality of drainage passages or drains 60 that move away from the reservoir. The drains 60 described above are located along the inner portion of the sides 56 of the reservoir around the periphery of the melted area 50. In other embodiments, the sides 56 of the reservoir can be formed by different components. The link 44a to the right of the longitudinal center line 1 of Figure 3 shows an example of such a case. This link 44a is formed all the way through the various components of the sanitary napkin 20 (except the backsheet 30). The drains 60 that move away from the reservoir formed by this link can be formed by portions of any of the different components or layers of the sanitary pad 20 through which the link opening 52 passes. It will be understood that the links 44 described in FIG. the present can be formed deep enough to pass part or all of the various components or layers of the sanitary napkin 20 as long as certain requirements are met. Preferably, as in the case of the first link embodiment described above, the melted area 50 is located below the face facing the core 28b of the top sheet 28. This provides a link structure that will not interfere with the drained to the underlying layers. The preferential link should also produce side walls 56 that are open to at least some of the layers below the top sheet 28. The side walls 56 formed by the layers lying below the top sheet 28 do not need to be open, without embargo. For example, alternating layers may have side walls 56 that are sealed. The link should not produce side walls 56 that seal any of the underlying layers that are supposed to remain open for the transport of liquids. This can be achieved if the material or materials comprising these underlying layers have melting temperatures that are higher than that of the material of the topsheet 28 (or other layers to which they melt). The material or materials comprising these layers must also have higher melting temperatures than those created in the melting process. A final requirement is that the link does not create an opening completely through any lower layer, such as backsheet 30, which is intended to be impervious to liquids. It is also possible that drains 60 can be formed by structures other than hollow spaces in adjacent layers. This may cause the drains 60 to be in locations other than those portions of the acquisition layer 34 that are located on the periphery of the melt area 50. For example, as shown in Fig. 8, the drains 60 may also be formed in the melted area 50. The drainages 60 can be formed by cracks 70 in the melted area 50 at the bottom of the reservoir structure. In other embodiments, 50 holes 72 can be intentionally formed in the melted area. For example, a device 74 used to create the fusion links 44 is shown in Figure 8A. The device 74 (part of which is shown) may have a head 76 equipped with one or more piercing elements 78 extending from its link surface 80. When the link 44 is formed, the bonding surface 80 will form the melted area 50. The piercing elements 78 are used to leave the holes 72 in the cast area sufficient to form drains 60. It is even possible that the piercing elements can pierce and / or break some of the fibers 42 of the underlying layer. This embodiment is significant insofar as it provides a link structure that is an exception to the general preference (described below) for deeper links. This structure will allow the transport of liquids to the underlying layers even though the link 44 may be a relatively shallow bond having a melted area 50 in the interface between the bonded layers. In another example, shown in Figure 11 (and described below in greater detail), the openings 29 in the topsheet 28 (or portions of the openings 29) can provide the drains 60 in the underlying layer. As shown in Figure 11, the sides 56 of the reservoir can be formed entirely by portions of the topsheet 28. The absorption of body exudates at the binding sites has been observed as a rather unusual phenomenon. While not wishing to be bound by any particular theory, it is believed that the sanitary napkin 20 functions in the following manner. When the liquids are placed on top sheet 28, some of these liquids will flow into link openings 52. This takes place rather quickly. The liquids can then be held momentarily in the link openings 52. It is believed that this provides the benefit of removing them from contact with the wearer's skin. After the exudates are held for a short period, they are suddenly drained into the acquisition layer 34. In other embodiments, the exudates may not be retained even temporarily. In these latter embodiments, the exudates will flow immediately through the drains 60 and into the acquisition layer 34. In this way, it is believed that the melted areas 50 which are formed where the upper sheet 28 and the layer are bonded of acquisition 34 do not affect the passage of liquids undesirably. In addition, contrary to what one might think, instead of blocking the transfer of liquids to the absorbent core 32, sanitary napkins with top sheets of films with openings that have links with larger surface areas (and thus, larger melted areas) ) seem to perform no less well than those with small links, with the proviso that the total linked area does not become excessive. The larger linked areas 44a, in fact, can also create a visual impression of increased absorbency. The larger links 44a, in this way, may be distributed as in the preferred embodiment shown in Figure 1, to create an increased absorbency impression in the longitudinal central region 46. It has been found that visual printing is important between Consumers because it is often difficult for them to believe that a sanitary napkin will perform properly when it becomes very thin. While not wishing to be bound by any theory, it is also believed that when relatively deep links 44 are used, the structure formed by the link has additional features. Figures 11 and 12 show these characteristics schematically. As shown in Figure 11, it is believed that the use of deep links causes the portions 28 'of the topsheet 28 immediately adjacent to the areas 50 to curve (or move) toward the link opening. This can have several effects. The openings formed by the deep bonds can form a cup-shaped depression. The cup-shaped depression may have a mouth opening 62 that is wider than the bonded area 50 that forms the base of the cup. In other words, the cup structure has tapered side walls 56. It is believed that this is caused by the depth and penetration towards the non-woven acquisition layer 34. This stretches the top sheet material 28 over the portions of the acquisition layer material. non-woven 34 surrounding the links 44. It is believed that this cup structure provides the advantage of a good acquisition. As shown in Figure 11, stretching of the upper sheet material 28 in the area of the deep links 44 can cause the openings 29 in the upper sheet 28 to turn outward, to the sides. The apertures 29 have axis designated by a reference letter "a". These axes define the alignment of the openings 29. The axes are oriented ordinarily in the Z direction. When the openings 29 are turned outward, their axes have a horizontal component (ie, in the X-Y direction). This orientates the apertures 29 toward the adjacent portions of the acquisition layer 34, rather than toward the melted area 50. This may provide the benefit of transferring liquids through the apertures 29 toward the acquisition layer 34. The structure shown in FIG. Figure 12 provides a contrasting example of a shallow link 44. The term "shallow link", as used herein, refers to bonds that penetrate not more deeply than the interface between the faces of the two materials when their faces are placed adjacent to each other. The shallow links, as shown in Figure 12, create flat fused areas 50. These flat fused areas 50 are similar to those previously formed when an impermeable link is created around the periphery of a sanitary napkin. Flat fused areas 50 provide no way for liquids to be transmitted to the underlying layer unless they have holes or cracks, as described above. The linking patterns can be in an infinite number of patterns, such as any of the differently arranged links arranged in the form of rows, geometric shapes, graphic patterns, straight lines or curves, intermittent lines, etc. In addition, the pattern or patterns do not have to be evenly distributed, or even in the same pattern on the sanitary napkin. It is also possible that different link patterns, etc. they can be used between different components of the sanitary napkin 20. For example, the upper sheet 28 and the immediately underlying layer can be linked with a pattern, and the laminate formed by them can be bonded to another layer using a different bonding pattern. Figure 13A shows a link pattern in the form of wavy lines. The linked pattern can even be used to direct liquids from one region of the sanitary napkin to another. For example, liquids deposited in the area of these wavy lines will tend to flow along and within these lines. In yet other alternative embodiments, a padding pattern may be used to provide the sanitary pad with a softer feel. Figures 13B-13D show an example of the use of a linking pattern to at least partially assist the sanitary napkin 20 to assume a particular shape during use. The sanitary towel 20 shown has a bonding pattern in the shape of an oval. This particular bonding pattern is used in conjunction with the flexure-resistant deformation element 82 located on the garment-facing side 20b of the sanitary napkin 20. The flexure-resistant deformation element 82 comprises a sheet that it has ribs 84 and a channel 84 formed therein. The bending-resistant deformation elements are described in greater detail in the European patent applications published under numbers 0 335 252 and 0 335 253, published on October 4, 1989 in the name of Kenneth B. Buell. As shown in Figure 13DWhen the sanitary napkin is subjected to laterally inwardly compressed forces, it forms a structure of the type described in greater detail in the above European patent applications. Another suitable bonding pattern that can help form a particular structure may be a pattern in the form of two inward, opposite, concave lines, oriented longitudinally, arranged on opposite sides of the longitudinal center line 1. Fusion of the top sheet 28 and the acquisition layer 34 may also provide other advantages. For example, it is believed that using melting instead of adhesives can increase the overall flexibility of the product. Although one does not wish to be limited by any theory, it is believed that this can be attributed to several factors. The removal of adhesives removes an additional layer of material. In particular, it removes a relatively stiff material (the adhesive layer). In addition, it is difficult to bond such materials with adhesives. The adhesives are typically applied in layers or lines. These are generally less flexible arrangements than a dot pattern due to their tendency to unduly restrict portions of the materials bonded against sliding over or over one another. The actual flexibility of the sanitary napkin, however, will depend on the particular bonding pattern used. For example, if a plurality of extremely small points, spaced very closely spaced, is used, the flexibility may not be less than in products having adhesive-bonded layers, because closely spaced interlinked areas cause the linked areas to cover the entire total area similar to a layer of adhesives. Flexibility, on the other hand, can be improved if the bond pattern is in the form of a continuous or intermittent line if the line is oriented to create an axis around which the sanitary napkin can be folded. The topsheet 28 and the acquisition layer 34 can also be secured at least partially by any other suitable joining means or combinations of such other means and the above joining means. The topsheet 28 and the acquisition layer 34 can be joined at least partially by any means known in the art, such as adhesives. If adhesives are used, the adhesives can be applied in a continuous, uniform layer, a patterned layer, or an array of lines, spirals or separate points of adhesive. The adhesive bond preferably comprises an open-pattern network of filaments of adhesive, as described in U.S. Patent No. 4,573,986, issued to Minetola et al. On March 4, 1986, or an open-pattern network of filaments. comprising various lines of adhesive filaments in a spiral pattern, as illustrated by the apparatus and method shown in U.S. Patent Nos. 3,911,173, issued to Sprague, Jr. on October 7, 1975; 4,785,996, issued to Zieker et al. On November 22, 1978; and 4,842,666, issued to Werenicz on June 27, 1989. Suitable adhesives are manufactured by Findley Adhesives Incorporated, of Elm Grove, Wisconsin, United States, and sold as H-1077 or H-1137. In yet other embodiments, the topsheet 28 and the acquisition layer 34 can be joined at least partially by mechanical and thermomechanical entanglement. The fibers of the acquisition layer 34 may be interlaced in any of the above specified ways to form the upper sheet of film interlaced with fibers. C- The Absorbent Core The absorbent core 32 is positioned between the topsheet 28 and the backsheet 30. The absorbent core 32 provides the means for absorbing menstrual fluids and other body exudates. The absorbent core 32 is generally compressible, conformable and non-irritating to the wearer's skin. The absorbent core 32 may comprise any material used in the art for that purpose. Examples include natural materials such as cotton, shredded wood pulp, which is generally referred to as air felt, folded cellulose wadding, swamp moss, cross-linked cellulose fibers, absorbent foams, absorbent sponges, synthetic fibers, polymeric fibers, agents polymerizing hydrogel forming gels, or any equivalent material or combinations of materials. In the embodiment shown in Figures 1-3, the absorbent core 32 is a laminate comprising a layer of superabsorbent polymeric material, such as in the particulate form, disposed between two fabrics placed in air, the first tissue layers. and second (or layers of "upper" and "lower" tissue). The first and second fabric layers provide containment of the superabsorbent polymeric material, improve the lateral impregnation of the absorbed exudates throughout the absorbent core 32 and provide some absorbency. A suitable laminate is the Water-Lock L-535 superabsorbent laminate, available from Grain Processing Corporation of Muscatine, Iowa, USA (Water-Lock is a registered trademark of Grain Processing Corporation). Such superabsorbent laminates are described in U.S. Patent Nos. 4,467,102, issued to Pedersen et al., On August 21, 1984, and 4,260,443, issued to Lindsay et al. On April 7, 1981. The polymeric gelation agent which is employed in the absorbent core 32 will generally comprise particles of a polymeric hydrogel-forming material. The term "particles", as used herein, may refer to particles of any form, such as in the form of beads, flakes or fibers. The characteristics of the absorbent core 32 (including, but not limited to, the preferred types of polymeric materials used herein, and the types of methods that can be used to prepare these polymeric particles) are described in greater detail in the United States patents. United • Nos. 4,673,402, issued to Weisman et al., 5,009,653, issued to Osborn, and the patents incorporated by reference in that patent, the descriptions of which are all incorporated by reference herein. In a preferred embodiment of the above embodiment, the absorbent core 32 is a laminate, as described above, that is grooved or partially grooved to have longitudinal extension capability, as shown in Figure 15 of the accompanying drawings. This grooved or partially grooved core is described in greater detail in the patent applications of the capillary channel fibers. In another preferred embodiment of the above embodiments, the absorbent core 32 comprises fibers blown in the melted state. Such an absorbent core can be useful separately in absorbent articles that are not constructed with fused layers. (This also applies to other cores and components described herein.) Fibers blown in the melted state are preferably treated to make them hydrophilic. Any suitable process for making the hydrophilic fibers can be used for this purpose. This type of absorbent core 32 can be used to provide the sanitary napkin 20 with a bi-modal pore size distribution between the acquisition layer 34 (or other overlying layer) and the absorbent core 32. The term "size distribution of bi-modal pore ", as used herein, refers to a pore size distribution such that the overall pore size distribution of the absorbent core material 32 does not include a significant number of pore sizes in the same range as the acquisition layer. 34 (ie, there is no substantial overlap in pore sizes between the two components). Figure 20 is a graph showing an example of the pore size distribution of an acquisition layer (the Fukamura material, as named in the graph) and an absorbent core layer blown in the melted state (designated "MB" in the graph). Figure 20 shows that the total pore size of the absorbent core 32 should be smaller than the overall pore size distribution of the acquisition layer 34. The bi-modal distribution is particularly useful for establishing a capillary gradient between a layer or component superior and a layer or inferior or underlying component.

In another embodiment, the pore sizes may be distributed such that there is a three-dimensional pore size gradient in the absorbent core (or in some other absorbent structure or structures). For example, the absorbent core may be provided with a capillary gradient with larger capillaries in the area where liquids are typically deposited on the absorbent core (ie, in the liquid acquisition zone), and smaller (and even smaller) capillaries in those regions located away from the acquisition zone in the longitudinal direction (or direction of the machine), the transverse direction (or direction transverse to the machine), and / or the Z direction. Such a structure may be made by some suitable variation of the process described below with reference to Figure 18 (i.e., varying the distances of the blow dies in the melted state from the surface on which the fibers are deposited). The embodiment that has the three-dimensional gradient of pore sizes must be able to distribute liquids even better, thereby increasing the utilization of the effective capacity of the core. It is believed that this is particularly important in structures containing superabsorbent material. It is believed that the increased distribution of liquids allows liquids to come in contact with the surface of more superabsorbent material, and increase the effective capacity of the absorbent structure.

The fibers used for the melt-blown core can comprise any type of fibers that are suitable for use in melt-blow processes. Such fibers include, but are not limited to, polyethylene, polypropylene, and nylon fibers. The fibers used in the melt-blown core are preferably hydrophilic polyethylene fibers, similar to those used in the interlaced film with fibers shown in Figure 7. Such fibers have a diameter ranging from about 1 to about 100 microns. , preferably around 1 to about 20 microns. Such fibers are generally known as "micro denier" fibers, since they have a fiber denier of less than 1. Such fibers must have lengths of less than about 1.5 inches, and preferably such fibers have lengths of between about 0.01 and 1 in. . The absorbent core 32 is preferably made of one or more wefts of polyethylene fibers blown in the melted state. Such wefts preferably have a basis weight of between about 60 to 180 g / yd2, and an average wet pore radius size (which may be referred to as "average wet pore size radius", or for simplicity "size "average wet pore", or similar terms used herein) of between about 30 and 40 microns uncharged, and a global pore size distribution such that about 90% of the pores in the raster have pore radii wet between about 10 and 80 microns without load. The wet pore size radius is measured according to the "procedure for liquid extrusion analysis" described in Section 4 of this description. The blown-in construction provides the absorbent core with 32 pores of smaller size than those present in some of the fabric wefts previously used in absorbent cores. These smaller pore sizes are compared with those of conventional air-laid paper core material (marked as Ft. Howard paper) in Figure 21. Fibers blown in the melted state also cause the absorbent core 32 to be resilient. In particular, the melt-blown web is sufficiently resilient so that the pores defined by the fibers blown in the melted state tend to maintain their size when wetted and when placed under pressure. Fig. 22 is a graph comparing the pore size of a core material blown in an uncharged melted state (tests numbers 1 and 2) with the same core material blown in the melted state under a 1/4 psi load (Fig. g / cm2). It is believed that pores of the melt-blown core retain at least about 90% of its pore size when they are under a load of 1/4 psi (18 g / cm2). The smallest pores, combined with the tendency to retain the pore size under load, provide the sanitary napkin 20 with a capillary gradient sustained from the topsheet 28 towards the absorbent core 32 and a capillary distribution network supported within the absorbent core. The capillary distribution network held within the absorbent core blown in the melted state 32 referred to above can be summarized as follows. Typically, the above cellulose absorbent cores had relatively small pore sizes. However, when the liquids were deposited in such nuclei, the moistened cellulose material collapsed. This reduced the pore size of the moistened cellulosic material. However, the surrounding dry cellulosic material retained its pore size. This caused the problem that the moistened cellulose material was surrounded by dry cellulose material having larger pores. This destroyed the capillary distribution network within the cellulosic core to such an extent that it became difficult for liquids to be transported from their point of entry into the core to other portions of the absorbent core. It is believed that the melt-blown cores of the present invention reduce or eliminate this effect. It is believed that the cores insufflated in the melted state provide a sustained distribution network of liquids when wet and when they are under pressure. This allows liquids to be transported to other parts of the absorbent core, and make use of other parts of the core. This, in effect, increases the effective storage capacity of the absorbent core when compared to absorbent cores comprising cellulosic fibers only. Such behavior is especially apparent in the absorbent cores insufflated in the melted state described herein. This is due to the improved resilience and the small capillary size of the core structure blown in the melted state. The absorbent core structures insufflated in the melted state described herein differ from absorbent cores made from other types of resilient materials. Other absorbent cores made of resilient materials were generally made of relatively large, resilient and resilient fibers. These fibers, although useful to create a resilient structure, created large pores in the structure. This had a negative impact on the capillary network of the absorbent core. The use of such fibers blown in the melted state, resilient in the construction of the absorbent article can also provide the absorbent article with other desirable characteristics. These may include better fit, which results from the potential ability to make the absorbent article thinner (in at least some of the embodiments described herein). Fibers blown in the melted state can provide the absorbent article with increased flexibility, too. Increased flexibility, such as thinness, can also result in improved fit and comfort. In addition, the resilience of the melt-blown component provides a structure that will not only have a capillary network that is resistant to collapse, but will tend to make the entire absorbent article more resistant to collapse as well. The resilience of the absorbent article can be used to provide the absorbent article with a greater capacity to cover a given area of the wearer's undergarments because it will have a reduced tendency to collapse (i.e., to bulge) due to the forces exerted on the article. absorbent during use. Such forces include the inwardly oriented compression forces exerted by the interior of the wearer's thighs. The resilience of the absorbent article will tend to cause the absorbent article to return to its original shape when such forces are removed. It is believed that this provides the absorbent article with better sustained fit and better area coverage during the dynamic conditions encountered when the absorbent article is being used. This potential for greater area coverage sustained during use, together with a more aggressive liquid handling capacity due to the bi-modal pore size distribution, can provide the absorbent article with better protection against leakage. The absorbent cores insufflated in the melted state 32 described herein may be in a non-limiting number of different arrangements. In one embodiment, the absorbent core 32 may comprise a single layer or web having the basis weight noted above. The single layer may have particles of superabsorbent material dispersed therein, for example in the form of a homogeneous mixture, etc. In another embodiment, the absorbent core 32 may comprise a laminate of superabsorbent material in the form of particles, fibers or the like, between two webs of blown fibers in the melted state. As in the case of the paper laminate / superabsorbent material, the material blown in the melted state may be in the form of two separate webs, or it may comprise a single web of blown material in the melted state bent in C or bent in E, around the superabsorbent material. The core 32, in such an embodiment, is constructed in a manner similar to the paper laminate and superabsorbent material described above, only with the weft or webs blown in the melted state replacing the paper webs. In another embodiment, the absorbent core 32 may comprise a single layer or web having the aforementioned overall basis weight. However, in this embodiment, the frame is provided with two or more regions having different pore sizes. This embodiment can be made during the process of depositing blown fibers in the melted state to form the weft. For example, a melt-state blowing process such as that shown in Fig. 18 can be used. Fig. 18 shows that the fibers are deposited from a die 102 on a surface. The die 102 is located at a specific distance from the surface. The closer the die 102 is to the surface, the denser the fibers that will be deposited (under a given air flow rate of the fibers). The process used to make the embodiment described herein would typically use one or more dies located along the surface. These dies are located at different distances from the surface. The melt-blown process will produce a single web with denser areas (smaller pores) where the dies are closer to the surface, and less dense areas (larger pores) where the dies are farther from the surface. In another embodiment, shown in Figure 23, the absorbent core 32 may comprise particles of superabsorbent material 88 having filled fibers 90 thereon, such as described in U.S. Patent No. 5,002,814, issued to Knack et al. others on March 26, 1991. The use of such material in the absorbent core 32 allows the inclusion of fibers such as polypropylene, polyethylene, PET, rayon and cellulose fibers in the core with particles of superabsorbent material. Such particles of superabsorbent material filled with fibers are preferably contained within a matrix of blown fibers in the melted state, such as between two layers of fibers blown in the melted state 92 and 94. The fibers blown in the melted state in the layers can be melted to the filled fibers on the particles of superabsorbent material. Alternatively, or additionally, the fibers blown in the melted state in the two layers can be interlocked with or bonded together, and the particles of superabsorbent material filled with fibers therebetween. Figure 23 (although not necessarily drawn to scale) shows that such an embodiment can be used to provide relatively large pores around the particles of superabsorbent material. These large pores provide space for the particles of superabsorbent material to swell when absorbing liquids. It is believed that this reduces incidents of gel blockage in the small pores of the inflated network in the melted state. It is also believed that particles of superabsorbent material filled with fibers retain the particles of superabsorbent material in their place better, particularly when surrounded by an inflated matrix in the melted state. This reduces the undesirable tendency of such particles to come into contact with the wearer's skin. - ßß - In a variation of the embodiment described above, the absorbent core 32 may comprise a structure of two or more layers comprising a layer blown in the melted state and a second layer with particles of superabsorbent material (particles filled with fiber, or particles of superabsorbent material without attached fibers) between them. The second layer can be a paper web or a non-woven web carded or linked by twist. The advantage of such a structure is that the superabsorbent particles or the fiber-filled particles can be used to jointly secure the layers. These layers can be secured together by treating one or both layers which will be arranged adjacent to the particles of superabsorbent material with some suitable solvent, and then securing the wefts using the particles of superabsorbent material filled with fibers or not filled with fibers and a combination of heat and pressure to induce a permanent bond. In this process, the particles of superabsorbent material serve as a primary or secondary binder to hold the layers together. Figure 24 is a schematic diagram of an apparatus and a process for making such a laminate of superabsorbent material. The preferred embodiment of the apparatus 110 comprises a first unwind support 112, a first unwind roller 114 that feeds a weft A to the process, a second unwind roller that feeds a weft B to the process, a pair of applicators of solvent 118, a particle applicator of superabsorbent material 120, a conveyor belt 122, two heat and pressure cut-outs 124 and 126 formed between a pair of rollers 128 and 128 'and 130 and 130', respectively, a highlight cut-out and drying 132 formed between two rollers 134 and 136 and a take-up roller 138. In a preferred embodiment of this process, the solvent used is water. The first layer preferably comprises a double layer composite designated A / A 'in Figure 24. The layer A comprises a web or layer of polyolefin fibers blown in the melted state such as those described above. The layer A 'is a layer that is used to tie the superabsorbent material. The layer A 'is placed adjacent to the superabsorbent material on the opposite side of the superabsorbent material from the second layer, B. Preferably, the layer A' comprises a layer of moisture absorbing fibers such as a weft of nylon fibers known as Hydrofil. , available from Allied Signal, Inc., of Hartford, Connecticut, United States, or rayon fibers such as those available from Courtaulds Fibers, Ltd., of the West Midlands, England. The second layer, B, comprises a weft placed in air or a layer of wet laid paper. The use of such an absorbent core embodiment 32 can further simplify the construction of the sanitary napkin. This embodiment eliminates the need to fold a paper web in two layers to contain the particles of superabsorbent material. It also eliminates the need for hot melt adhesives between these layers and can minimize any resulting stiffness caused by any other adhesives used therein. It can also simplify construction because the absorbent core material can be conveniently formed into a continuous weft that can be fed separately to the process used during construction of the sanitary napkin (ie, the core can be assembled off-line to simplify the conversion to the final product). In a further variation of such a product, the layer B of the combination may serve as a top sheet or as a secondary top sheet (ie, an acquisition layer) of the sanitary napkin. This, in effect, will provide a combined top sheet. This variation will further simplify the construction of the sanitary napkin 20, and also allow the thinnest sanitary napkin to be made, more flexible and at the same time more resilient, for an improved fit. In any of the embodiments that use one or more wefts of fibers blown in the melted state, the weft or frames can be provided with characteristics that improve the distribution of liquids. For example, the web or webs of blown fibers in the melted state can be highlighted with a pattern of spaced lines running in the longitudinal direction of the machine to improve the distribution of liquids in the longitudinal direction. In still another alternative embodiment, a process of blowing in the melted state can also be used for other purposes. For example, a melt state process can be used to seal the perimeter of an absorbent core, particularly one that contains particles of superabsorbent material. The perimeter can be sealed to prevent particles of superabsorbent material from escaping from the core and coming into contact with the wearer's skin. Typically, in the past, this was done by wrapping the absorbent core in a paper, or by bending the edges of the core, or by making the core of a bent laminate, and the like. However, the melt-blown process can be used to blow in the melted state a thin epidermis of fibers on each side of the absorbent core to prevent particles of superabsorbent material from leaving the absorbent core. If the epidermis or layer of fibers blown in the melted state is sufficiently thin, it is believed that it does not adversely affect the fluid handling characteristics of the absorbent core. The process of blowing in the melted state can also be used to blow fibers in the melted state onto "those portions of the core that are arranged around the edges of the core. This will seal the edges. These alternative processes can be carried out on cores made from a variety of materials, including cellulosic materials. They are not limited to nuclei made of fibers blown in the melted state. The absorbent core materials insufflated in the melted state are particularly useful with the secondary top sheet materials carded or twisted linked described in Section 2B of this disclosure. The absorbent cores insufflated in the melted state are particularly suitable for use with an acquisition layer 34 comprising a hydrophilic polypropylene web, twisted or carded, having a basis weight of between about 16 and 32 g / yd2 and a radius of average wet pore size between about 40 and 90 microns, without load, and between about 20 and 80 microns under a load of 1/4 psi, and a global distribution of pore sizes such that about 90% of the pores of the weave have wet pore radii between about 20 and 125 microns without load. Alternatively, the twisted or carded polypropylene web may comprise part of a combined topsheet material. Figures 4-6 show a particularly preferred absorbent core 32, which will be referred to as a "mixed" core. This particular core arrangement is shown in a relatively thick sanitary napkin 20. However, it can also be formed into a thin weft for use in thin products. The mixed absorbent core 32 comprises a fiber batt, preferably in the form of a homogeneous fiber mixture. The mixed core 32 comprises at least two groups (or types) of fibers. These include a first group (or type) of relatively short low denier hydrophilic fibers, and about 5%, preferably at least about 10 or 20% to about 90% longer, higher denier synthetic fibers. , which comprise a second group (or type) of fibers. The mixing ratio of the two fiber groups can be varied to produce the desired properties for different types of absorbent articles. (All percentages stipulated in this description are by weight, unless otherwise stated. The first group of fibers can comprise natural fibers such as cotton fibers, cellulose or other natural fibers. The first group of fibers may alternatively or additionally comprise synthetic fibers, including but not limited to rayon, thermomechanical chemical pulp (or "CTMP" or "TMP"), milled wood, or chemically modified fibers, such as crosslinked cellulose fibers. For one embodiment, the first group of fibers comprises fibers of shredded wood pulp known as air felt. The fibers of the first group of fibers are inherently hydrophilic, or can be rendered hydrophilic by treating them in any of the manners previously described to render them hydrophilic. Performance is improved by selecting a relatively stiff fiber that maintains a substantial portion of its compressive strength when wetted. (That is, the fibers must have a high compression modulus.) Preferably, the selected fibers are both resistant to compression and wet and dry resilient (ie, they tend to resist both compression and spring when compressed) . Crosslinked cellulose fibers are especially preferred for these criteria. (However, it will be understood that crosslinked cellulose fibers are sufficiently modified so that they can no longer be considered as cellulosic, or natural fibers, by themselves.) The second group of fibers must also be of high compression modulus and it must maintain a relatively high module when it is moistened. The second group of fibers should also preferably be wet and dry resilient. Suitable fibers include, but are not limited to, synthetic fibers comprising any of those materials noted above as suitable for use as fibers of the acquisition layer 34. (However, lengths of fiber, denier, etc. are not necessarily equal. preferred lengths of fiber, etc., are described below.) The fibers of the second group of fibers are preferably longer than the fibers of the first group. Preferably, the fibers of the second group are greater than or about 1/4 in (about 0.6 cm) long, and more preferably are greater than or about 1/2 in (about 1.3 cm) long. The denier of the fibers of the second group is preferably greater than the denier of the fibers of the first group. The fibers of the second group preferably have one denier per filament of between about 6 and about 40. More preferably, the denier is between about 15 and about 30, and most preferably between about 15 and about of 25. The fibers of the second group of fibers can be hydrophilic, hydrophobic or partially hydrophilic and partially hydrophobic. The fibers of the second group preferably have at least some hydrophilic component (preferably a cellulosic component). The fibers of the second group of fibers can be provided with a hydrophilic component in various suitable forms. These include, but are not limited to, coating or treating the fibers to make them, or at least their hydrophilic surfaces. A suitable type of synthetic fibers for use in the second group of fibers are folded polyester fibers. Suitable synthetic fibers are available from Eastman Kodak Textile Fibers Division, of Kingsport, Tennessee, United States, under the Kodel 200 and 400 series. One suitable type of synthetic fiber is Kodel 410 fiber. A suitable polyester fiber is fiber Kodel 431. These Kodel fibers are preferably folded * at a fold frequency of between about 5 and 7, preferably about 6, more preferably 6.3 folds per linear inch (i.e., per 2.5 cm). The fibers are preferably folded at a fold angle of between about 70 and about 91 °, preferably around 88 °. Folding provides the fibers with improved resilience, among other desired properties. The fibers have a denier of 15 per filament and a length of about 0.5 in (about 1.3 cm). They can be coated with a hydrophilic or hydrophobic finish by any suitable method known in the art. In an alternative embodiment, it is possible to replace the cellulose fibers of the first group with very short, low denier synthetic fibers (with hydrophilic surfaces). The mixed core 32 in this situation would consist of short, low denier, hydrophilic synthetic fibers of the first group (such as polyester fibers with the Celwet finish) and long, high denier synthetic fibers of the second group of fibers. Such a mixed core may also contain particles of hydrogel-forming polymer gelation agents, to increase the absorption capacity of the core. In a preferred embodiment, the hydrogel-forming polymeric gelation agents comprise "high-speed" absorbent gelation materials. The term "high-speed" absorbent gelling materials, as used herein, means those absorbent gelling materials that are capable of absorbing exudates at a rate such that they reach at least about 40%, preferably at least about 100%. 50%, and most preferably at least about 90% of its capacity in a time less than or equal to about 10 seconds. A suitable method for the percentage rate of capacity is described in U.S. Patent Applications Nos. 07 / 637,571, filed by Noel et al., And 07 / 637,090, filed by Feist et al. In alternative embodiments, it is also possible that the high speed absorbent elation materials are blended with other types of absorbent (or ordinary speed) gelation materials. Preferably, in the embodiment described immtely above, the high-speed absorbent gelation materials are in fibrous form. Such fibers (although not necessarily fibrous, high-speed absorbent gelation materials) are discussed more fully in U.S. Patent No. 4,855,179, issued August 8, 1989 to Bourland et al. The term "fibrous absorbent gelation materials", as used herein, is intended to include absorbent gelation materials in the form of fibers that fully comprise an absorbent gelation material and bicomponent fibers that at least partially comprise other materials which have their surfaces coated with absorbent gelation materials. A suitable high-speed fibrous absorbent gelation material is known as Fibersorb SA7000, formerly manufactured by Arco Chemical Company, of Newton Square, Pennsylvania, United States. It is believed that the effective use of polymeric gelation agents, forming hydrogels, is improved in such a mixed core. The use of higher concentrations of polymeric gelation agents, forming hydrogels, is also possible. The mixed absorbent core 32 is preferably compressed to a density of at least about 1.5 g / in 3 (about 0.09 g / cm 3). The mixed core 32 can be compressed to densities of at least as much as 4.0 g / in 3 (about 0.25 g / cm 3) to improve fluid impregnation while maintaining good smoothness and flexibility. (The density values specified above do not include the weight of any particle of absorbent gelation material.) Densification can be applied to the entire absorbent core 32 or only to selected portions. The densification in a pattern allows to adapt the properties of fluid handling to a specific need. For example, the density can be very low in the white area of fluids to maximize the speed of fluid acquisition, and the density can be very high near the edges of the core to maximize the impregnation of fluids. In a particularly preferred embodiment, the improved absorbent core 32 is an air-laid mixture composed of approximately 15% folded polyester fibers of 15 denier per filament, 0.5 in long, and approximately 85% crosslinked cellulose fibers , compressed to a density of about 1 g / in3 (about 0.06 g / cm3). The mixed absorbent core 32 can be used as the entire core or can be used as one or more layers in a layered construction. The mixed absorbent core 32 can be used with or without the acquisition layer 34. Figures 4-6 show an example of a core 32 in which layers of core material are used to produce a sanitary towel 20"profiled". The sanitary towel 20 profiled is thicker in the center of the sanitary napkin and tapers so as to be thinner towards the edges 22 and 24. Figures 5 and 6 show that such sanitary napkin 20 can be made by stacking layers having relatively large length and width dimensions over those with smaller length and width dimensions (or vice versa). In a layered construction, one or more layers may consist of nothing more than cellulose or mixtures of cellulose / polymeric hydrogel-forming material. The layers may also have different fiber content and / or absorbent gelation material. For example, a greater percentage of absorbent gelation material may be provided in the lower layers to provide additional liquid storage capacity. It is believed that the mixed absorbent core 32 provides improved performance. It is believed that the blended absorbent core provides improved fluid acquisition rate and absorption capacity. It is believed that these improvements also result in reduced leaks. The absorbent core can also be made smaller and thinner to make the item more comfortable and discreet to use. It is believed that the strength of the core is also improved due to the content of synthetic fibers. It is believed that these improved characteristics are due to several factors. The absorbent cores of the present composition have a lower wet density than the nuclei composed entirely of cellulose. The lower wet density results from the presence of synthetic fibers. No water is absorbed by the synthetic fibers, so that the modulus of the fibers does not change when they get wet and do not collapse. The lower wet density provides the blended absorbent core with improved fluid acquisition rate and absorption capacity. The lower wet density allows any polymeric hydrogel forming materials included in the fiber matrix to absorb a larger amount of liquids as there is more room for the polymeric materials to swell. It is believed that the first group of fibers helps reduce leaks. The mixed core provides a number of small capillaries that would not have a core composed of 100% large synthetic fibers. These small capillaries allow the core to pull fluids through the top sheet and away from the wearer's skin. This improves the performance of leaks due to a reduction in the volume of fluid that can leave the product running along the surface of the skin. The first group of fibers of the mixed core also provides an impregnation capacity. This capacity is a result of the small capillaries mentioned above. This capillarity can be improved by core densification. The cellulose allows the core to be maintained at a high density when dry, which generally can not be achieved with only synthetic fibers. The presence of the synthetic fibers allows the portions of the core that are moistened to expand and this reduces the density of these portions. The densified neighboring areas that are still dry have a high density and provide small capillaries. The liquidsAs a result, they will tend to impregnate themselves in these neighboring areas. This maintains the absorption capacity and the acquisition speed. It is believed that the folded synthetic fibers provide the core with improved compression and resilience resistance. Resilience keeps the hollow space in the core even after liquids are absorbed into the core and pressure is applied to it. The hollow space provides additional storage space for absorbed liquids. It also provides additional space in which absorbent gelation materials can be inflated after admitting liquids. The characteristics of other types of absorbent cores are described in greater detail in the patents and documents incorporated herein by reference. Additional features are described in the patents and other documents incorporated by reference in those documents. The disclosure of all this background is incorporated herein. In addition, other suitable absorbent core arrangements are described in U.S. Patent Nos. 4,988,344 and 4,988,345 and European Patent Application, Publication No. 0 198 683, published October 22, 1986 in the name of Duenk and others. . Other possible materials for the core 32 are described in U.S. Patent No. 4,475,911, issued to Gellert on October 9, 1984. The sanitary napkin (or other absorbent article) 20 may also include additional layers or other components such as those described in the patents incorporated by reference. For example, the absorbent article may comprise a crosslinked cellulosic fiber patch or adission layer placed between the topsheet 28 and the absorbent core 32.

D. The Back or Back Sheet The back or back sheet 30 is impervious to liquids. The backsheet 30 serves to prevent menstrual fluids and other body exudates from soiling the wearer's clothes. Any material used in the art for that purpose can be used herein. Suitable materials include highlighted or non-highlighted polyethylene films and laminated paper. A suitable polyethylene film is manufactured by Monsanto Chemical Corporation and sold as film No. 8020. In an alternative embodiment of the sanitary napkin 20 (typically in which the topsheet 28 overlays only the main body portion 21 and is not extends outwardly to form the upper surface of the fins 36), the rear sheet 30 may comprise two layers. In such a case, the backsheet 30 may comprise a first layer of bulky material disposed on the side facing the core 30a of the backsheet. The purpose of the first layer is to provide a non-irritating, comfortable surface against the wearer's body. The bulky layer may comprise any suitable material, such as a nonwoven material. The second layer may be disposed on the garment side 30b of the backsheet 30, and may comprise a fluid impervious film. It has been found that a low density polyethylene material of about 0.01 to about 0.05 mm thick, preferably about 0.02 mm thick, works well as this second layer. A polyethylene film, such as that sold by Ethyl Corporation, Visqueen Division, under model XP-39385, has been found particularly suitable for this second layer. The backsheet 30 can also be made of a soft, fabric-like material that is hydrophobic relative to the topsheet 28. A backsheet of polyester or polyolefin fibers has been found to work well. A particularly preferred, soft, cloth-like backing sheet material 30 is a laminate of a non-woven polyester material and a film such as that described in U.S. Patent No. 4,476,180, issued to Wnuk October 9, 1984. In other embodiments, the backsheet 30 is extendable. An extensible backsheet 30, particularly preferred, is an extended adhesive film, formula No. 198-338, manufactured by Findley Adhesives Company, of Wauwatosa, Wisconsin, United States, which is described in greater detail in the patent applications of the capillary channel fibers. As shown in Figures 1 and 2, the topsheet 28 is preferably secured to the backsheet 30 along a seam 64 around the periphery 26 of the sanitary napkin 20. The seam 64 can be formed by any means commonly used in the art for this purpose, such as gluing, folding or fusing. This is a preferred embodiment for ease of construction. (Other means may be used to join the various elements.) For example, other possible embodiments include one in which the absorbent core 32 is essentially completely wrapped with the topsheet 28 before it is placed on the backsheet 30. The sanitary napkin 20 may also comprise an absorbent core that possesses sufficient integrity to be alone and that is permeable to liquids on one surface while the other surface has been treated to render it impervious to liquids. Figures 1 and 2 also show the fasteners, such as adhesive fastening means 38, which are adapted to secure the sanitary towel 20 to the crotch region of an undergarment. Suitable adhesive fasteners are described in greater detail in U.S. Patent No. 4,917,697. The fasteners used with the present invention are not limited to adhesive bonding means. Any type of fastener used in the material can be used for this purpose. For example, the sanitary napkin 20 can be secured to the wearer's underwear by means of the fastener described in U.S. Patent No. 4,946,527, entitled "Pressu-re-Sensitive Adhesive Fastener and Method of Making the Same", issued to Battrell on August 7, 1990. The adhesive attachment means 38 is covered by removable release liners, designated 40. The pressure sensitive adhesives must be covered with release liners 40 to prevent the adhesives from sticking to foreign surfaces. Before its use. Suitable release liners are described in U.S. Patent No. 4,917,697. A suitable wrapper that serves both as a package for a sanitary napkin as well as an adhesive cover on the sanitary napkin is described in U.S. Patent No. 4,556,146, issued to Swanson et al., December 3, 1985. 3. Alternative Forms of Realization There are also several possible alternative embodiments of those described above. A non-limiting number of these alternative embodiments will be described below. Fig. 14 shows an alternative embodiment in which the acquisition layer 34 is stretched before it is fused to the upper sheet 28. The upper sheet 28 and the acquisition layer 34 form a laminate. When the stretched laminate is relaxed, the laminate has tuft areas 66 formed therein between the bonded areas 44 and the valleys 68 in the bonds. The embodiment »shown in Figure 14 provides a key advantage. It allows (as well as various alternative embodiments thereof) to form a stretchable laminate from materials that ordinarily are not considered as stretchable. The top sheet 28 of plastic film with openings, for example, is not normally considered as extensible. However, the top sheet 28 is provided with a degree of extension capacity when it is secured to a layer such as the acquisition layer 34 after it has been extended and bonded, and subsequently the two component materials are relaxed. The tufted areas 66 in such a laminate can also provide certain benefits. Areas with ßß lock are typically soft. They will also place the absorbent fibers of the acquisition layer 34 closer to the wearer's body than the linked areas without tufts. While not wishing to be bound by any theory, it is believed that this construction can improve absorption (particularly in areas with tufts 66). The absorption of liquids in the Z-direction (ie towards the plane of the sanitary napkin 20) as well as the impregnation of fluids in the X-Y plane (in the plane of the sanitary napkin 20) can be improved. There may be several reasons for this. It is believed that the improved absorption in the Z direction is a result of the stretching of the acquisition layer 34. The stretching of an acquisition layer 34 made of fibers blown in the melted state or linked by rotation in the XY plane causes the spaces between fibers, measured in the XY plane, increase in size. When the forces of. Stretching, the friction between the fibers makes it difficult for these types of fibers to return to their original position. The size of the spaces between the fibers, in this way, is increased permanently, making the acquisition layer 34 more permeable to liquids in the Z direction. It is believed that the impregnation of liquids in the XY plane is due to the provision of valleys 68 formed between areas with tufts. In some embodiments, it may be desirable for valleys 68 to run in the longitudinal direction so that liquids are impregnated toward the ends of sanitary napkin 20. In other embodiments, it may be desirable for valleys 68 to run in transverse direction so that the laminate is longitudinally extensible. In other alternative embodiments, both the upper sheet 28 and the acquisition layer 34 can be stretched before melting them together. In another alternative embodiment, the fusion bond can be used as primary means or as supplementary means to provide openings 29 in the upper sheet of film 28. Prior to bonding, the upper sheet 28 can be a film without apertures, or can have fewer openings than desired in the finished product. The openings 29 can be formed by the device 74 shown in Figure 8A. The melt, in the first case, can form all the desired openings 29 in the upper sheet 28. In the second case, the melt can provide several openings that complement the original number of openings in the upper sheet 28 to provide a total desired number. of openings. In yet another alternative embodiment shown in Figure 17, the merge can create a different type of link structure. Figure 17 shows an embodiment in which a portion of the topsheet 28 is heated to make it soft and deformable. The heated area of the topsheet 28 is subjected to relatively high pressure to create bonded areas 44. The topsheet 28 is not heated sufficiently to melt these bonded areas 44 during the process. In this way, the material of the upper sheet 28 does not flow together to completely close the openings 29 in the linked areas. In this way, the link forms linked areas 44 in which the original openings 29 provide drainage passages. However, the heating causes the three-dimensional film to collapse to a virtually two-dimensional structure in the area of the link 44. The heating may also cause the openings 29 in the film of the upper sheet 28 to assume irregular shapes. The links 44 in Figure 17 are formed when the deformable material of the topsheet 28 is forced into contact with the fibers 42 of the nonwoven material. This makes the The material of the upper sheet 28 is interld around the fibers 42. As shown in Figure 17, this may cause some fibers 42 to extend toward openings 29 or outwardly from an opening 29. A particularly preferred type upper sheet 28 which can be used in the embodiment shown in figure 17 is a heat-sealable film. Thermo-sealable films can be used to create such a bond 44 at lower temperatures and pressures. Heat-sealable films are available with one layer or side that is heat-sealable and one that is not. Such a film is useful as it can be placed with the heat-sealable side adjacent the non-woven layer and then bonded. Suitable heat sealable films are commercially available. The embodiment shown in Figure 17 is another example of a type of structure that will not interfere with the flow of liquids even if it can create a shallow bond having a fused area in the interface between the two bonded layers. In another embodiment, the acquisition layer 34 may comprise a combined two-layer structure. The combined structure of two layers may comprise a structure having a bi-modal pore size distribution within itself. Such a structure may comprise a hydrophilic, carded or twist-linked fabric of polyester, polyethylene, polypropylene or the like, having fibers blown in the melted state (such as those described above for use in the absorbent core blown in the melted state) attached to its lower side. As noted above, carded fabrics can be linked in many different forms, such as thermally bonded, twist-linked, needle-punched or bonded by means of powders. Alternatively, such a structure may comprise an embossed web in the melted state which is attached to the underside of the carded web or linked by rotation by means of highlighting or melting in the melted state. It is also believed that joining hydrophilic micro-denier fibers directly to the underside of the carded or spin-linked fabric and removing adhesives therebetween, improves the transport of liquids towards the absorbent core 32. This is mainly due to the strong traction capillary generated by the small pores of the network of fibers blown in the melted state that become part of the acquisition layer. Preferably, the fibers blown in the melted state in such embodiments are deposited in a thin layer. The fibers blown in the melted state are preferably deposited in a layer not exceeding 30 g / m2. Preferably, the combined acquisition layer is also thin. Preferably, the combined basis weight does not exceed 50 g / m2. This will facilitate the movement of liquids towards the core, and will reduce the possibility that they tend to stay in this combined layer. Melting fibers in the melted state directly onto the carded or bonded cloth can also help during the melting process. The presence of fibers blown in the melted state, particularly if they have the same polymer chemistry as the upper sheet, is very useful since these fibers are compatible in the molten state with the upper sheet. The consequence of such compatibility is a higher bond strength between the top sheet and the acquisition layer. In a preferred alternative of the invention shown in Figure 26, instead of comprising a two-layer combined structure, the acquisition layer 34 may comprise a carded nonwoven web that is made of two or more groups of fibers having deniers. different For example, the acquisition layer may comprise a first group of fibers having a relatively large first denier (e.g., a denier ranging from 2.2 to 6.0 denier per fiber) and a second group of fibers having a second, smaller denier. (for example, 0.1 to 2.2 deniers per fiber). A nonwoven web, carded, can be constructed so that within the carded web, the first group of fibers lies on (as close as possible to the upper web) the second group of fibers. Such a construction has the advantage that a capillary gradient can be built into the acquisition layer 34 instead of having to secure two layers together to create a capillary gradient. This preferred variation comprises a hydrophilic carded or spin-linked fabric preferably comprising polyethylene, polyester, polypropylene, rayon or acrylic acetate fibers. The carded or twist bonded fabric preferably has two different average pore size wet radii. The part of the structure containing the large denier fibers preferably has an average wet pore size of between about 50 and 140 microns, with no load. The part of the structure containing the lesser denier fibers preferably has an average wet pore size of between about 7 and 50 microns, with no load. Any of these combined fabrics can, but does not need, to be linked by fusion to the upper sheet. Although several preferred embodiments of sanitary napkins of the present invention have been described, numerous other types of sanitary napkins are available and described in the literature. These can be provided with the molten layers of the present invention. These sanitary napkins include those described in U.S. Patent Nos. 4,285,343, issued to McNair on August 25, 1981; 4,589,876 and 4,687,478, granted to Van Tilburg on May 20, 1986 and August 18, 1987, respectively; 4,917,697 and 5,007,906, granted to Osborn and others on April 17, 1990 and April 16, 1991, respectively; and 4,950,264 and 5,009,653, granted to Osborn on August 21, 1990 and April 23, 1991, respectively; and in U.S. patent application Serial No. 07 / 605,583, filed October 29, 1990 in the name of Visscher and others. The terms "panty lining" or "panty lining" refer to absorbent articles that are less bulky than sanitary napkins that are usually worn by women between their menstrual periods. Suitable absorbent articles in the form of panty liners that can be described with the fused layers herein are described in U.S. Patent No. 4,738,676, entitled "Pantiliner", issued to Osborn on April 19, 1988. The term "incontinent article" refers to pads, undergarments (pads held in place by means of a suspension system of the same type, such as a belt or the like), inserts for absorbent articles, capacity enhancers for absorbent articles, tricks, pillows for bedding and the like, regardless of whether they are used by adults or other incontinent persons. Suitable incontinent articles that can be provided with the melted layers described herein are described in U.S. Patent Nos. 4,253,461, issued to Strickland et al. On March 3, 1981; 4,597,760 and 4,597,761, awarded to Buell; 4,704,115 mentioned above; 4,909,802, issued to Ahr et al .; 4,964,860, issued to Gipson et al. On October 23, 1990; and in U.S. Patent Applications Nos. 07 / 637,090 and 07 / 637,571, filed respectively by Noel et al. and Feist et al. on January 3, 1991. The term "diaper" refers to a used garment. usually by infants and incontinence that is placed between the legs and fastened around the user's waist. Suitable absorbent articles, at least some of which are in the form of diapers, which can be provided with cast layers are described in U.S. Pat. Nos. Re. 26,152, Duncan et al., Issued January 31, 1967. 3,860,003, granted to Buell on January 14, 1975; 4,610,678 granted to Weisman et al. Dated September 9, 1986 4,673,402, granted to Weisman et al. On June 16, 1987 4,695,278, granted to Lawson on September 22, 1987 4,704,115, granted to Buell on November 3, 1987 4,834,735 , granted to Alemany et al. on May 30, 1989 4,888,231, issued to Angstadt on December 19, 1989; and 4,909,803, issued to Aziz et al. on March 20, 1990. Descriptions of all patents, patent applications (and any patents granted based thereon, as well as any published foreign patent applications) and the publications mentioned. throughout this description they are incorporated herein by reference. However, it is not expressly admitted that any of the documents incorporated herein by reference teach or describe the present invention. It is also not expressly admitted that any of the commercially available materials or products described herein teach or describe the present invention. In this way, the present invention provides absorbent articles having bonds between their layers, particularly their upper, superior liquid permeable layers, which maintain the bond held even under prolonged use. 4. Test Methods 180 ° Breaking Resistance Test The 180 ° bluff test described below is used to ensure that the bond between the fused layers is sufficiently strong. so that the top sheet 28 does not separate from the underlying layer. The 180 ° peel test essentially involves placing the melted layers in a tension tester and applying forces to separate the layers. The test is referred to as a "180o detachment" test because of the direction in which the detachment forces are applied. The sample is partially detached and oriented so that the non-detached portion of the sample and the layers to be peeled form a configuration that resembles two capital letters "L" placed back to back. The detachment forces are then applied in opposite directions on the partially detached components. Principle The voltage tester is a device constructed in such a way that a gradually increasing extension is applied smoothly to a defined sample., separating the layers, until one of the components of the sample fails (breaks) or the components separate. Scope The procedure is applicable to layered materials. Fourth conditioned appliance - controlled at 73 ± 2 ° F, 50 ± 2% relative humidity. Oven - Colé Parmer model N-05015-10. Cole-Parmer International, 7425 North Oak Park Avenue, Chicago, Illinois 60648, United States, or equivalent. Bracket - an aluminum bracket with 1 in. Wide spring clips. Cutter J.D.C. - Double edge cutter, 1 in (25.4 mm) wide, equipped with safety shield. Thwing-Albert Instruments Co., 10960 Dulton Rd., Philadelphia, Pennsylvania 19154, United States, or equivalent. Electronic tension tester - universal rate tension tester, elongation constant, with strip chart recorder, having a total range of 1,000 g, with other ranges available as required. Instron 1122 or 4201, Instron Engineering Corp., of Canton, Massachusetts, United States, or Thwing-Albert Intellect 500 or II, Thwing-Albert Instruments Co., 10960 Dulton Rd., Philadelphia, Pennsylvania 19154, United States, or equivalent. Jaws - light duty, with line contact faces (bar line). They are obtained from the appropriate instrument manufacturer, listed above. Sample Preparation Sample according to the sampling instructions. The samples are conditioned in a conditioned room at 73 ± 2 ° F, 50 ± 2% relative humidity, for a minimum of two hours. Each sample is labeled in a corner for identification. Be sure not to label so that the pen marks are in the area to be tested. For samples to be tested in the machine direction (MD) Using a cutter J.D.C. , four strips of 1 in (25.4 mm) in CD are cut by approximately 6 in (152.4 mm) in MD. For samples to be tested in the cross machine direction (CD) Using a J.D.C. cutter, four 1 in (25.4 mm) strips in MD are cut for approximately 6 in (152.4 mm) on CD. Instrument Preparation The voltage tester is calibrated and zeroed according to the manufacturer's instructions. A load cell is shrunk so that the voltage results for the strip tested are between 25 and 75% of the capacity of the load cell or the load range used. This range is initially set at 500 g of full scale. The length of the meter is set to 1 in. The crosshead of the instrument is set to operate at 22 in. Per minute (± 2 in. Per minute). The graph speed is set to 5 in per minute. The tension tester is fixed so that the crossed head travels a distance of 10.4 in. This will allow the tension tester to monitor the forces generated while the sample is shed a total of 7.3 in. The instrument is set to zero so that the pen rests on the vertical line of zero (distance axis) of the graph. The graph is rotated so that the pen also rests on one of the heavy horizontal lines (load axis) of the graph. Label the graph paper with the sample code, the proven address (MD or CD), the date of the test, the full-scale load value, the speed of the graph, the cross-head speed, the length of the meter, and the name of the test (link strength). Test Procedure By hand, approximately 1.5 in. Of the sample is separated at one end of the sample strip. Approximately 0.5 in. Of a sample layer is placed in the upper jaw of the tension tester. The jaw is closed. The remaining layers are placed on the lower jaw with enough tension to eliminate any slack, but not enough to move the pen from the zero mark. This jaw is closed. The voltage tester and the recorder are started simultaneously, as described in the manufacturer's instructions. After the components of the sample are separated (or one of the components fails (breaks)), the graph stops and the voltage tester is returned to its initial starting position. The sample is removed from the jaws and the graph is placed for the next sample. The procedure is repeated for each of the remaining strips of the sample. Calculations / Reports The most common points of interest in the analysis are loads (force in grams) when separation and failure occur. A. Link Resistance Strength in Separation For those instruments that are not capable of capturing and reporting the average forces of sample separation, a rule is used as a straight edge and the average force of separation in the graph is physically determined. to the nearest gram. For those instruments that are capable of capturing and reporting forces, the average force of separation from the digital screen to the nearest gram is read. B. Failure Link Strength Strength For those instruments that are not capable of capturing and reporting the peak force of the sample failure, the peak fault force in the graph is determined physically, to the nearest gram. For those instruments that are capable of capturing and reporting forces, the peak power of failure of the digital screen is read to the nearest gram. The four readings of the average forces in grams of the samples are averaged and reported, first at the separation and / or second the peak force of failure of the sample to the nearest gram. The bond strength of the separation is used to determine the average release resistance described above. Procedure for Liquid Extrusion Analysis Introduction Liquid extrusion analysis is useful to characterize the distribution of pore sizes in absorbent structures. The procedure for the analysis of liquid extrusion can be conceived as analogous to the situation that occurs when a person squeezes a wet article of clothing to dry it. Water is contained in the article of clothing in pores or pore-like structures of various sizes. To squeeze the article, pressure must be applied to the article.

At the start of the squeezing process, a relatively large amount of water can be extracted from the article of clothing with relatively small amounts of pressure. However, as the process continues, more and more pressure is required to extract water from the article. At the same time, less and less amounts of water will be extracted. This reflects the fact that the water was drained from the large pores at the beginning of the squeezing process. At the end of the process, the water that is being removed from the article is coming out of the smaller pores, and it is more difficult to remove. The liquid extrusion analysis uses a pressure chamber to provide controlled application of pressure on the article in question (rather than a squeeze procedure). The liquid removed from the article (the sample) is extruded through a membrane, and weighed on a scale. The apparatus used in the liquid extrusion analysis is shown schematically in Figure 27. The size of the pore radius drained at a given point in the conduction of the liquid extrusion analysis is determined by employing the Laplace transform of the Washburn equation. : R = 2 cos range (teta) adv (rec). / delta P where range is the surface tension of the fluid used; tit is the contact angle of the fluid and the sample, either advancing or receding; R is the radius of the pore that is being drained; and delta P is the change in pressure. Briefly, the instrument consists of a pressure chamber in which the sample is placed, a hose or pipe connecting the container to a tank, the tank itself, and the scale on which it rests. The pressure chamber should be a pore volume distribution unit (or "PVD" unit or "liquid extrusion" unit), such as that manufactured by TRI Company of Princeton, New Jersey, United States, or its equivalent. The pressure chamber has a series of slots in it. The pressure chamber contains a set of membrane discs. The discs serve as support and filtration medium inside the pressure vessel. A fluid runs through and between both "halves" of the instrument. The liquid extrusion analysis can be used to study pore volume distribution, hysteresis, swelling, compression, receding and advancing contact angles, surface pores, and multiple layers. Initial Placement First, the pressure chamber must be thoroughly cleaned before exposing it to any test fluid. The hose should be fixed at a high enough level so that the fluid does not flow out of the hose and into the tank during preparation. The fluid is initially placed in the tank as well as in the chamber, adding it slowly to avoid the formation of air bubbles. The new discs should be cleaned in toluene for about two or three minutes to remove any residual oil present from its manufacture. A new steel disc should be sprayed with three coats of epoxy coating (paint). The discs previously coated with epoxy are sprayed only twice. The coatings should be relatively light, spraying for approximately two seconds. The first, or two in the case of a new disc, should dry in half an hour. The last coating applied before joining the membrane should dry only for forty-five seconds. If there is a reflective side to the membrane, that should be the side attached to the disk. If a reflective side can not be discerned, either side can be used. After bonding, the disc and membrane are allowed to dry overnight on a soft surface, such as a paper towel, the membrane facing down, with a small weight (2-4 lb) on top. The excess membrane hanging on the side of the disc is removed with a flat blade, such as a screwdriver. The steel discs usually last for about twelve epoxy coatings. The membranes are usually changed due to age or punctures, the normal life of a membrane being two to three months if treated with care. When changing membranes, the old membrane must first be removed from the disc with a razor. Care should be taken that the metal edges do not rise from the disc during the withdrawal movement. Acetone or methylene chloride are used to clean the residual paint on the disc. Before locking into the pressure chamber assembly, the disc and membrane should be immersed in test fluid. A soft foam is placed over the pressure chamber before being treated with test fluid, adding fluid so that the chamber retains a high level of fluid. The metal clamping ring may need to be added to contain a fluid level that is high enough to cover the disk. The disc is fixed on the foam, with the membrane facing down, so that the disc is only semi-submerged in the fluid. After waiting for a few moments for the air to escape from the disc, the arrangement is then completely submerged, adding more test fluid. Again a little is expected for the air to escape, the disc is carefully removed from the pressure chamber and reversed quickly, all movement lasting only a fraction of a second. The foam is then removed and the disc is carefully placed with the right side up in the chamber. Air bubbles that congregate near or on the membrane and the chamber interface should be removed with a dropper. A plastic screen must be accommodated to suspend on, but not touch, the membrane while it is fixed with screws, etc. This will protect the membrane from damage while assembling the camera. It is of fundamental importance that the membrane is never touched. Touching the membrane will cause a micro-puncture in it, which will greatly affect the test results. A camel hair painter's brush should be used to clean the membrane of any residual fibers from the samples. Likewise, the painter's brush can be used to remove the samples from the pressure chamber after a test has been run. Start the system, or gain suction between the pressure chamber and the tank, must be done carefully and without the help of any artificial pressure. The level of the glass pipe is simply lowered until the fluid begins to flow into the opening where the pipe is attached to the tank on the balance. Just after the opening fluid begins to emerge, the glass tubing is placed in the reservoir, below the surface of the fluid. It can then be held. There must be no air trapped between the pipe opening and the tank. Any air bubbles that float in the tank must be removed using a dropper. Any air bubbles trapped in the pipeline must also be removed by raising and lowering the pipe by forcing air bubbles into the pressure chamber and out of the leveling cylinder. Next, the excess fluid that remains submerging the disc must be removed from the pressure chamber. This is done by opening the valve that drains fluid from the most outboard slot of the pressure chamber. After the disc and membrane are in place, with the fluid level in the pressure chamber below that of the membrane, the O-ring and the metal clamping ring are carefully placed on the top of the disc. The upper surface of the metal clamping ring should be cleaned of test fluid. Otherwise, the test fluid may enter the interior of the pressure chamber and affect the test results. The fluid that enters the screw holes of the metal clamping ring while the disc is immersed must be removed with a dropper. Some residual test fluid in the groove around the pressure chamber is beneficial as it prevents condensation inside the pressure chamber. Once everything is ready, the level of the pressure chamber is adjusted so that the level of the meniscus in the leveling cylinder is exactly uniform with its opening, and equilibrium is then expected. When the balance is reached approximately, the screw can be placed in the leveling cylinder. A small plastic disc should be placed between the reservoir and the balance to prevent tilting and provide greater stability. The hose that reaches the balance should be allowed to follow a natural path, avoiding any curves or bends. The path should also be free of any depressions or ridges; this alters the balance of the flow. Once a pipeline path has been set, it should be kept constant as best as possible. It must be stopped with freedom, so that the vibrations do not affect the measurement in the balance. The glass tubing that deposits the fluid in the reservoir, however, must be capable of being securely fastened to prevent vibration by displacement of the reservoir. Use of the Liquid Extrusion Unit Before the test is performed, a blank run must be made with the apparatus. This involves running a test without sample to the possible pressures to which the measurement may be desired. This blank run calibrates the device to take into account the fluid that is inevitably trapped in the upper part of the chamber, especially in the meniscus between the 0-ring and the membrane. Before running the tests, this membrane interface and the 0-ring should be rubbed very gently with a paper towel to remove any large amounts of fluid. The salvas should typically not be greater than two or three tenths of a gram. The air trapped between the membrane and the disk is a source of error, causing variability in the salvo. If, when doing a blank run, the mass of fluid in the balance seems to increase endlessly, never leveling, there is a hole in the membrane. In this case, the membrane must be changed. When you run samples that hold more than a couple of grams of fluid, you may want to pre-saturate the sample and then place it in the pressure chamber. For this purpose, it is useful to have a plastic fastener on which to place the sample while soaking. Also, it is a good idea to slide the sample of the fastener with the brush, as this allows you not to touch the membrane. Any excess fluid should then be wiped with a paper towel, gently. No attempt should be made to remove the final fluid residue; the small excess that can not be removed with a paper towel will soak the disc. Whether the sample is pre-saturated or left to be impregnated with fluid from the reservoir, the apparatus must reach a certain level of equilibrium, ie a stable state, before starting the test. This means that the mass on the scale is only changing by a defined amount, as discussed below. After this, a test can be started. The PVD is an instrument of balance. All tests must be initiated and executed at a predetermined equilibrium level. An "equilibrium constant" must be selected for this particular level of equilibrium. This number refers to the maximum rate at which fluid extrusion is considered trivial. This number depends on the degree of precision required. It is more an empirical rule than a constant. The supplier of the PVD unit suggests a rate of 2 mg / min per 1,000 mm3 of fluid extruded from the sample. For example, the equilibrium rate for a sample that retains one gram of fluid would be 1 g (1 cm3) (103 mm3) (2 mcx / min) (1 min) (1 g) (1 cm3) (1000 mm3) ( 60 sec) since 1 g is the extruded quantity, 1 cm3 / g is the density of the fluid, there is 103 m3 in 1 cm3, the suggested rate is 2 mg / min per 1,000 mm3, and there are 60 seconds in 1 minute. The previous example works at a rate of 0.033 mg / s. Since the scale only reads at the nearest 0.1 mg, an equilibrium rate of 0.1 mg / s would probably be sufficient. For a thick, typical absorbent core that retains 10 to 15 g of fluid, this turns out to be around 0.4 mg / s. Also, it has been suggested that this equilibrium rate be maintained for at least 30 seconds. Practically, what this means is that you simply set the desired pressure, wait for the balance to stop at the determined equilibrium rate, wait for 30 seconds, and finally record the mass on the balance. The pressure must be adjusted gradually and carefully. You should always approach white pressures from the same direction; If the pressure is increasing, it will always approach from a lower pressure, and vice versa. This restriction is due to the fact that the advancing and receding contact angles are different, and the same contact angle must be involved in each step of the test.

Data Analysis There are two main ways to display the data in the form of a graph. The first, volume distribution vs. radio, gives a quick detail of the pore volume distribution of a material. The second, the accumulated graph of total volume vs. radio, provides more information but less quickly. Grade the extruded percentage volume vs. radio gives the graph of volume distribution. Typically, bar graphs are used with the percentage volume on the Y axis and the radio ranges on the X axis. This is the first derivative of the accumulated graph. See Figures 20 and 21. Combining the accumulated graph involves representing the total extruded volume per gram of sample on the Y axis and the radio ranges on the X axis. This graph indicates the total volume or capacity per mass of the sample, although the volume distribution graph does not. Although particular embodiments of the present invention have been illustrated and described, it will be obvious to those skilled in the art that various other changes and modifications may be made without departing from the spirit and scope of the invention.

Claims (10)

1. NOVELTY OF THE INVENTION CLAIMS 1. An absorbent article comprising a liquid-permeable top sheet, a liquid-impermeable back or back sheet bonded to said top sheet; an absorbent core placed between said upper sheet and said backsheet, and an acquisition layer placed between said upper sheet and said absorbent core, said absorbent article characterized in that: said absorbent core comprises at least one resilient web of blown fibers in the melted state, wherein said web of fibers blown in the melted state comprises a plurality of fibers blown in the melted micro-nier state, having pores therebetween having a first average wet pore radius size without charge; and said acquisition layer has pores therein that have a second wet pore average radius size without load, wherein said second pore average radius size in wet is larger than said first wet pore average radius size. The absorbent article of claim 1, wherein: said web of melt-blown fibers comprising said absorbent core has a first average wet-pore radius size of between 20 and 40 microns, preferably between 30 and 40 microns , under a load of 18 g / cm2, a basis weight of between 44 and 162 g / m2, and a total distribution of pore sizes such that 90% of the pores in the weave have wet pore radii of between 7 and 70 microns, preferably between 7 and 50 microns, and said acquisition layer has a second average wet pore radius size between 40 and 140 microns under a load of 18 g / cm2, preferably between 40 and 90 microns without load, and a total distribution of pore sizes such that 90% of the pores in the frame have pore radius in humid between 10 and 150 microns without load. 3. The absorbent article of claim 1, wherein said absorbent core is in the form of one of the following structures: a laminate comprising said web of blown fibers in the melted state and at least one additional layer selected from the group consisting of a layer of paper placed in air, a layer of paper placed in wet, a weft of carded polyolefin, a carded weft of rayon and cotton fibers, a carded weft of PET, a spin-linked polyolefin weft, a weft of bound nylon per spin, and a PET plot linked by spin; a laminate comprising said web of fibers blown in the melted state and a second web of said fibers blown in the melted state with particles of superabsorbent material therebetween; a structure wherein said web of blown fibers in the melted state comprises a fiber matrix and said absorbent core structure further comprises a plurality of particles of superabsorbent material having relatively large first size fibers filled therein to form particles of filled superabsorbent material with fibers, said web of fibers blown in the melted state comprises fibers of a smaller second size, and said particles of superabsorbent material filled with fibers are surrounded by said matrix blown in the melted state of fibers; a laminate comprising a first layer and a second layer, wherein said first layer comprises said inflated web in the melted state of fibers, and said second layer comprises a material selected from the group consisting of a paper web, a non-woven web, carded , and a nonwoven web connected by rotation; and a plurality of particles of superabsorbent material between said first and second layers, wherein at least one of said first and second layers has been treated with solvents, and said first and second layers have been held together at least partially by said particles. of superabsorbent material with heat and pressure bonds. The absorbent article of claim 1, wherein said absorbent core has at least one of the following characteristics: said absorbent core comprises a single web of blown fibers in the melted state having two or more regions with different densities; said absorbent core is provided with a plurality of spaced apart protruding lines which are oriented generally in the longitudinal direction. The absorbent article of claim 1, wherein said acquisition layer has an upper surface and a lower side, and said fibers in said absorbent core have been blown in the melted state on the underside of said acquisition layer. The absorbent article of claims 1 or 5, wherein said acquisition layer comprises a fabric selected from the group consisting of the following: a carded polyester fabric, a carded polyethylene fabric, a carded polypropylene fabric, a fabric of spin-linked polyester, spin-linked polyethylene fabric, and spin-linked polypropylene fabric. The absorbent article of claim 1, wherein said acquisition layer comprises a two-layered composite structure comprising a carded or twist-linked fabric having an upper surface and a lower side, said web carded or twirled comprising a plurality of fibers having pores therebetween, each having a radius, where said pores have a radius of average wet pore size of between 50 and 90 microns without charge, and a global distribution of pore sizes such that 90% of the pores in the unloaded web have wet pore radii of between 10 and 150 microns, and a plurality of fibers blown in the melted state attached to the underside of said web carded or twisted, where said fibers blown in the melted state have pores between they, each having a radius, where said unloaded pores have a radius of average wet pore size of between 10 and 40 microns, and a global distribution of e pore sizes such that 90% of the pores in the unloaded frame have wet pore radii of between 7 and 70 microns. The absorbent article of claim 7, wherein said fibers blown in the melted state have been bonded to the underside of said carded or twisted web in one of the following ways: by blowing in the melted state said blown fibers in the melted state in the lower side of said carded or twisted web, or highlighting said blown fibers in the melted state on the underside of said carded or twisted web. 9. A method of making an absorbent structure for use in an absorbent article, said method comprising the steps of: (a) providing a first layer, said first layer having a pair of opposed faces; (b) providing a plurality of particles of superabsorbent material; (c) providing a second layer for attachment to said first layer, said second layer having a pair of opposed faces; said method characterized in that it comprises the additional steps of (d) applying a liquid solvent to at least one of said first and second layers; (e) placing said first and second layers in face-to-face relationship with said particles of superabsorbent material therebetween to form a laminate; and (f) bonding said first and second layers with said particles of superabsorbent material by applying heat and pressure to said laminate. The absorbent article of claim 1, wherein said absorbent core has a side facing the top sheet, a side facing the back or back sheet, and an underlying portion positioned between said side facing the top sheet and said side facing the backsheet of said absorbent core, and said absorbent core comprises: two layers of liquid permeable material comprising a first layer and a second layer, wherein the first layer is adjacent to the side facing the upper sheet of said core and said second layer is adjacent to the side facing the back sheet of said core; and a plurality of particles of superabsorbent material placed between said first and second layers of liquid permeable materialwherein said web of blown fibers in the melted state comprising said core forms the side facing the top sheet of said absorbent core, said web having pores of a size that allows liquids to pass therethrough to the underlying portions of said web. absorbent core, and another web of fibers blown in the melted state forms said side facing the backsheet of said absorbent core so that said particles of superabsorbent material are at least partially sealed within said absorbent core by said webs of fibers blown into the absorbent core. melted state forming the side facing the top sheet and the side facing the psoterior sheet of said absorbent core. IN WITNESS WHEREOVER, I sign the above, in this city of Mexico, D.F., on November 11, 1992. By THE PROCTER & GAMBLE COMPANY Manuel Gómez -Maqueo A.