MXPA99008881A - Shaped absorbent cores comprising multiple pieces and method for making same - Google Patents

Abstract

Disclosed is a shaped absorbent core suitable for absorbing and retaining aqueous body fluids. The absorbent cores comprise a front panel and a back panel. The front and back panels are made from fluid absorbent material, and each has an inner end, an outer end, and two sides. The inner and outer ends of each front and back panel have a length, with the inner end of each being shorter than the outer length of each. The front and back panels may comprise multiple layers of absorbent material. The absorbent cores also comprise a center section made from fluid absorbent material having first and second ends. The first end of the center section is in fluid communication with the front panel by overlapping the front panel intermediate the front inner and outer ends, and the second end is in fluid communication with the back panel by overlapping the back panel intermdiate the back inner and outer ends. A method of preparing a shaped absorbent core comprises the steps of providing at least one continuous rectilinear web of first absorbent material having a longitudinal axis and a pair of lateral edges defining a first width. A continuous rectilinear web of second absorbent material having a longitudinal axis and a pair of lateral edges defining a second width wider than the first width of the first absorbent material is formed with opposing generally arcuate notched areas in the lateral edges at spaced intervals along the web of second absorbent material. The web of second absorbent material is severed transversely along a line intersecting the opposed generally arcuate notched areas at spaced intervals to form sections having opposed notched ends. The sections are then positioned such that the notched ends are spaced apart and overlap the continuous rectilinear web of first absorbent material, forming layers of absorbent material. Then the layers of absorbent material are severed transversely at a point intermediate the notched ends.

Description

ABSORBENT FORMULATED NUCLEI COMPRISING MULTIPLE PIECES AND METHOD OF DEVELOPING THEMSELVES FIELD OF THE INVENTION The present invention relates to formed absorbent cores that are useful in absorbent articles, such as disposable diapers. This application is further related to a method for making these absorbent cores formed from multiple pieces of absorbent members.

BACKGROUND OF THE INVENTION Absorbent articles such as disposable diapers, incontinence pads, training pants, and catamenial towels generally include an absorbent core for receiving and maintaining body exudates. The absorbent core typically includes a fibrous web, which may be a non-woven web, placed with air, of natural or synthetic fibers, or combinations thereof. The fibrous webs used in these absorbent articles often also include certain gelling absorbent materials commonly referred to as "hydrogels," "super absorbent," or "hydrocolloid" materials for storing large amounts of the discharged body fluids. These materials absorb through capillary or osmotic forces, or a combination of both. Alternate absorbent materials capable of providing capillary transport of the fluid are open cell polymeric foams. If done properly, open cell polymeric foams provide capillary acquisition, transport and storage characteristics of the fluid required for use in high performance absorbent cores for absorbent articles such as diapers. Absorbent articles containing these foams may also possess desired wet integrity, providing adequate fit throughout the entire period that the article is worn, and can prevent shape changes during use. In addition, absorbent articles containing these absorbent foam structures may be easier to manufacture on a commercial scale. For example, the absorbent foam cores of the diaper can be simply stamped out of the continuous sheets of foam and can be designed to have considerably greater integrity and uniformity than air-laid fibrous absorbent cores that contain particulate gelling absorbent materials. In addition to absorbency and ease of manufacture, another desirable property of open cell polymer foams is the ability to make formed or contoured absorbent cores having various shape configurations, fluid absorbency properties, and usage characteristics. For example, formed or contoured absorbent cores made from open cell foam materials having the characteristics of particularly desirable fluid transport are disclosed in U.S. Patent No. 5,147,345 issued to Young et al. On September 15, 1992 and hereby incorporated and by reference. The absorbent core of the patent 5,147,345 to Young et al., Comprises a fluid acquisition / distribution component can be fibrous or foam based, as well as a fluid storage / redistribution component comprising an open cell polymer foam, flexible, hydrophilic The formation of the formed or contoured absorbent cores from foam materials, including those disclosed in Young Patent 5,147,345 and others, is advantageous in that the material is easily formed into webs that can be processed as a roll material. For example, the hourglass-shaped foam layer shown in Figures 2 and 9 of Young's patent 5,147,345 and others is typically made from a weft material processed from the roll material by trimming, cutting, separating and formed otherwise to form the hourglass-shaped piece. Nevertheless, because each hourglass-shaped layer is cut from a single piece of material, it has substantially uniform material properties, and the absorption characteristics of the layer are also substantially uniform. Therefore, the fluid is absorbed from one layer to the next, from an acquisition layer to a storage layer, for example, if the capillary absorption pressure of the absorbent layer exceeds the desorption pressure of the donor layer. However, the use of an hourglass-shaped layer limits the overall efficiency of the absorbent core by placing the material in areas where it can not be needed. For example, the acquisition layer may include material in the waist area where it is not typically needed, and the storage layer may include material in the crotch area where it can not be desired. Also, during the formation of the hourglass shapes, a significant amount of foam waste can be created that can no longer be used. Other absorbent materials, such as nonwoven materials suitable for processing from a roll material, are also typically substantially uniform in nature. Therefore, although most readily processable materials from a roll material can be formed into formed absorbent cores, the resulting absorbent cores have uniform characteristics of the material such as thickness and chemistry, resulting in uniform absorbent characteristics. Accordingly, it would be desirable to be able to independently vary the characteristics of the material of an absorbent core in previously determined regions of the absorbent article, thereby varying the absorption characteristics of the predetermined regions, but still be able to efficiently elaborate the core from suitable plots for processing from the roll material in a way that minimizes the use of the material and the generation of waste. It would also be desirable to make an absorbent article with areas of the absorbent article subjected to the rapid acquisition of fluid, such as the crotch area, formed to provide for rapid acquisition and distribution to other regions of the absorbent article formed for storage and / or redistribution. the fluid. It would further be advantageous to be able to independently vary all material characteristics of the various parts of an absorbent core, such as thickness, shape, and chemistry, thereby minimizing waste while also providing the absorbent characteristics. formed, resulting in optimal fluid handling and greater comfort for the user.

BRIEF DESCRIPTION OF THE INVENTION The present invention relates to absorbent cores formed which are suitable for absorbing and retaining aqueous body fluids. The absorbent cores comprise a front panel and a back panel. The front and rear panels are made from a fluid absorbing material, and each has an inner end, an outer end, and two sides. The inner and outer ends of each front and back panel have a length, with the inner end of each being shorter than the external length of each. Preferably, the sides of each of the front and rear panels that are attached to their respective internal ends by an edge that generally defines arcuate notches. The front and rear panels may comprise multiple layers of absorbent material.

The absorbent cores also comprise a central section made of a material that absorbs from the fluid having first and second ends. The first end of the center section is in fluid communication with the front panel by overlapping the intermediate front panel to the front and outer front ends, and the second end is in fluid communication with the rear panel by overlapping the intermediate rear panel to the later internal and external ends. In a preferred embodiment, the central section comprises at least one generally rectilinear absorbent strip member. The present invention also relates to a method for preparing a core. Absorbent formed which, in. One embodiment comprises the steps of providing at least one rectilinear continuous web of the first absorbent material having a longitudinal axis and a pair of side edges defining a first width. This web of the first absorbent material eventually forms the central section of the absorbent core. In a preferred embodiment, three rectilinear continuous webs of the first absorbent material comprise discrete layers, with at least one layer exhibiting better fluid acquisition or acquisition / distribution properties, and at least one layer exhibiting better storage / redistribution properties. In one embodiment, a rectilinear continuous web of second absorbent material having a longitudinal axis and a pair of side edges defining a second width wider than the first width of the first absorbent material is formed with areas with generally opposite arched notches in the side edges at spaced intervals along the weft of the second absorbent material. The web of the second absorbent material is separated transversely along a line intersecting the arcuate notched areas generally opposite at spaced intervals to form sections having ends with opposite notches. The sections are then positioned in such a manner that the notched ends are spaced apart and overlap the continuous rectilinear web of the first absorbent material, forming layers of the absorbent material. Next, the layers of the absorbent material are transversally spaced at an intermediate point to the notched ends, thereby forming a formed absorbent core having a front panel and a back panel of the second absorbent material which is located above a central section of the first absorbent material, generally forming the front and rear panels and the central section an elongated hourglass shape.

BRIEF DESCRIPTION OF THE DRAWINGS Although the description concludes with the claims pointing out in a particular manner and claiming the present invention differently, it is believed that the present invention will be better understood from the following description in combination with the figures of the accompanying drawings, in which Similar reference numbers identify similar elements, and where: Figure 1 is an exploded perspective view representing the relationship between the elements of an embodiment of an absorbent core formed of the present invention. Figure 2 is an exploded perspective view depicting an absorbent core formed of the present invention in a disposable diaper. Figure 3 shows a top plan view of an absorbent core formed in accordance with the present invention. Figure 4 shows a longitudinal cross-section of an embodiment of the absorbent core formed shown in Figure 3. Figure 5 shows that in longitudinal cross-section another embodiments of an absorbent article formed as depicted in Figure 3.

Figure 6 shows in longitudinal cross-section a further embodiment of an absorbent article formed as shown in Figure 3. Figure 7 shows in longitudinal cross section yet another embodiment of an absorbent article formed similar to the core shown in Figure 3. The figure 8 schematically shows an apparatus for forming an embodiment of the absorbent cores formed in accordance with the method of the present invention. Figure 9 schematically shows an apparatus for forming another embodiment of the absorbent cores formed in accordance with the method of the present invention. Fig. 10 schematically shows an apparatus for forming yet another embodiment of the absorbent cores formed in accordance with the method of the present invention. Figure 11 schematically shows an apparatus for forming yet another embodiment of the absorbent cores formed in accordance with the method of the present invention. Fig. 12 is a plan view of a relatively wide rectilinear continuous web after forming the notches. Fig. 13 is a plan view of a relatively wide rectilinear continuous web after a first cutting operation to produce discrete sections. Fig. 14 is a plan view of the discrete sections of the relatively wide rectilinear pattern in layers in a spaced apart relationship on the relatively narrow rectilinear continuous webs. Figure 15 is a plan view of the formed, finished absorbent cores of the present invention as produced by a method of the present invention.

DETAILED DESCRIPTION OF THE INVENTION As used herein, the term "absorbent core" refers to a material or combination of materials suitable for absorbing, distributing, and storing aqueous fluids such as urine and certain other body exudates. The term "absorbent article" refers to devices that absorb and contain exudates from the body by the use of an absorbent core, and, more specifically, refer to devices that are placed against or close to the user's body to absorb and absorb. contain the various exudates discharged from the body. The term "disposable" is used herein to describe absorbent articles that are not intended to be washed or otherwise restored or reused as an absorbent article (i.e., they are intended to be discarded after a single use and preferably , to be recycled, composted or otherwise disposed of in an environmentally compatible manner.) A preferred embodiment of an absorbent article of the present invention is the disposable absorbent article, diaper 60, shown in Figure 2. As used in US Pat. the present, the term "diaper" refers to an absorbent article generally worn by infants and incontinent persons which is worn around the wearer's lower torso. It should be understood, however, that the present invention is also applicable to other absorbent articles such as incontinence briefs, incontinence undergarments, diaper liners and fasteners, training pants, diapers that are worn, feminine hygiene garments such as sanitary napkins, and the like.

The Formed Absorbent Core Figure 1 shows an exploded perspective view depicting the elements of an embodiment of the formed absorbent core 10 of the present invention as it may be used in an absorbent article, for example, in a disposable diaper. As shown in Figures 1 and 3, the absorbent core 10 comprises a front panel 20 and a back panel 30, both made of absorbent material, preferably material suitable for storing or storing / redistributing fluid. The front panel 20 has an external front end 21, and an inner front end 22, and a pair of sides 23. Similarly, the rear panel 30 has an external rear end 31, an inner rear end 32, and a pair of sides 33. The front panel 30 has trimmed areas 40 where it is removed from the material at the intersection of the sides 23, and the inner front end 22. In the same manner, the rear panel 30 has trimmed areas 40 at the intersection of the sides 33, and the inner rear end 32. The trimmed areas 40, or notched portions, join the sides and the inner ends in such a way that the resulting widths of the inner ends 22 and 32 are narrower than those of the outer ends 21 and 31, respectively. By "notched" it will be understood that the place where an angle and end meet at an angle create between straight, some amount of material is removed from the corner to produce an additional portion of edge that joins the side and the end. The additional edge portion of the groove 40 may be generally straight, but in a preferred embodiment it is concave and generally arcuate, as shown in Figure 3. It is also contemplated that the groove may have generally straight sides, with the limiting example resulting in a rear or front panel that is substantially trapezoidal in shape. In a generally flat, unfolded state, the front panel 20 and the rear panel 30 are positioned such that the inner front end 22 of the front panel 20 is opposite to and separated from the inner rear end 32 of the rear panel 30 as shown in FIG. Figures 1-3. The distance between the front and rear panels can be varied as necessary. In general, the distance will increase as the length of the crotch increases with the size of the absorbent article. Figure 1 further shows the central section 50 of the absorbent material which is above the front and rear panels 20 and 30. The central section 50 is preferably generally rectilinear. By "generally rectilinear" it will be understood that preferably the center section is of substantially constant width along its length, such that they can be supplied out of the roll material when the absorbent core of the invention is made by the present method invention. In general, however, the central section 50 only needs to extend and overlap the still and posterior panels 20 and 30, and may have a variable width along its length. As shown, the generally rectilinear central section 50 extends from approximately the outer front end 21 of the front panel 20, to approximately the outer rear end 31 of the rear panel 30. In use, it is only necessary that the center section be in fluid communication with the front and rear panels 20 and 30, with the ends of the central section overlapping the front and rear panels 20 and 30 intermediate to their respective internal and external ends. For the same materials and configurations, it may be desirable to bond the layers of the absorbent core by adhesive to fix predetermined regions in relative relation to adjacent layers. It is contemplated that the fixed connection of the central region without overlapping the front or rear panels may be desirable, as long as this connection does not prevent fluid transfer. The joining method, whether overlapped or not, can be by any suitable method known in the art, such as by spraying adhesive in the subject regions of the absorbent core during manufacture.

The central section 50 may comprise multiple strips of absorbent material, for example strips 51 and 52, each strip potentially having individual characteristics of acquisition, acquisition / distribution, storage, or storage / redistribution of fluid, as well as individual shape characteristics, width, length and thickness. For example, in a preferred embodiment, at least two resilient, flexible, relatively thin polymeric foam strips 51 are made from the same storage / redistribution material as the front and rear panels 20 and 30. Strips 51 and the front and rear panels 20 and 30 which, having similar absorption characteristics and which are in fluid communication, act as the main storage / redistribution members. In a preferred embodiment, a generally rectilinear strip 52 comprising a resilient, flexible, relatively thin, polymeric foam material having greater fluid acquisition / acquisition / distribution characteristics than the strips 51, thereby tending to acquire rapidly and dividing the body exudates for the faster absorption towards the storage / redistribution layers 51 and the front and rear panels 20 and 30. The fluid absorbing members of the present invention can be used in disposable products that are capable of absorbing significant amounts of bodily fluids, such as urine, sweat, menses, and water in body wastes. These articles can be prepared in the form of disposable diapers, catamenial pads, incontinence trusses for adults, and the like. These absorbent articles generally comprise three basic structural components. As discussed in detail below, with reference to Figure 2, 1 component is a backsheet substantially impermeable to liquids. On top of this backsheet there is an absorbent core which may itself comprise one or more other layers. At the top of this absorbent core and attached to the backsheet is a topsheet permeable to the fluid. Preferably, the topsheet and the backsheet are bonded directly to the periphery of the absorbent article by an adhesive or other bonding means known in the art. The top sheet can also be adhered to the absorbent core. Figure 2 shows an exploded perspective view of an absorbent core 10 according to the present invention as contemplated for use in a disposable diaper 60. However, it should be understood that the present invention is also applicable to other absorbent articles such as incontinence trusses, incontinence pads, training pants, diaper inserts, sanitary napkins, and the like. The diaper 60 shown in Figure 2 is a simplified absorbent article that can represent a diaper before it is placed on a wearer. It should be understood, however, that the present invention is limited to the particular type or configuration of the diaper shown in Figure 2. The disposable diaper 60 is shown in its non-contracted state (ie, with generally all of the contraction induced by the elastic removed) to more clearly show the construction of the diaper 60. The diaper 60 may comprise a top sheet 61 peelable to the liquid; a back sheet 62 impervious to the liquid attached to the top sheet 61; and an absorbent core 10 positioned between the sheet exceeded 61 and the back sheet 62. Additional structural features such as elastic members and fastener for securing the diaper in place on a wearer (such as tape tab fasteners) can also be included. ). Although the topsheet 61, the backsheet 62 and the absorbent core 10 can be assembled in a variety of well-known configurations, a preferred diaper configuration is generally described in U.S. Patent No. 3,860,003 (Buell) issued April 14. January 1975, which is incorporated by reference. Alternatively, the preferred configurations for disposable diapers herein are also disclosed in U.S. Patent No. 4,808,178 (Aziz et al.) Issued February 28, 1989.; U.S. Patent No. 4,695,278 (Lawson) issued September 22, 1987; that and in United States Patent No. 4,816,025 (Foreman) issued March 28, 1989, which are incorporated by reference. Figure 2 shows a preferred embodiment of the diaper 60 in which the upper sheet 61 and the back sheet 62 are coextensive and have length and width dimensions generally greater than those of the absorbent core 10.1a upper sheet 61 which is attached with and on lay on the back sheet 62 thus forming the periphery of the cloth! 60. The periphery defines the outer perimeter or edges of the diaper 60. The topsheet 61 is docile, of soft feel, and non-irritating to the wearer's skin. In addition, the topsheet 61 is permeable to liquid allowing liquids to easily penetrate through its thickness. A suitable top sheet 61 can be manufactured from a wide range of materials such as porous foams, cross-linked foams, plastic films with openings, natural fibers (e.g., wood or cotton fibers), synthetic fibers (e.g. of polyester or polypropylene) from-a combination of natural and synthetic fibers. Preferably, the topsheet 61 is made of a hydrophobic material to isolate the user's skin from the liquids within the absorbent core 10. A particularly preferred topsheet 61 comprises fibers of polypropylene cut length having a denier of about 1.5, such as Hercules type 151 polypropylene sold by Hecules, Inc. of Wilmington, Delaware. As used herein, "short length fibers" refers to those fibers having a length of at least about 15.9 millimeters. There are a number of manufacturing techniques that can be used to manufacture the top sheet 61. For example, the top sheet 61 can be nonwoven, woven, glued, carded, or the like. A preferred top sheet is carded, and thermally bonded by means well known to those skilled in the art of fabrics. Preferably, the topsheet 61 has a weight of about 18 to about 25 grams per square meter, a minimum dry tensile strength of at least about 400 grams per centimeter in the machine direction, and a tensile strength. wetted at least about 55 grams per centimeter in the transverse direction of the machine. Although it is preferred to have a top sheet as the material closest to the user's skin, this is necessary. It is contemplated that a suitable configuration of the absorbent core can be used without a top sheet and still produce desirable results such as comfort and absorbency, as well as simplicity in manufacturing and cost savings of the material. For example, the body side surface of the absorbent core itself can be made of non-irritating, docile, soft, liquid-permeable materials that replace a separate top sheet. This absorbent core would only need to be used in combination with a backsheet to provide comfort and absorbency in an absorbent article. The backsheet 62 is impervious to liquids and is preferably manufactured from a thin plastic film, although other flexible liquid impervious materials may also be used. The backsheet 62 prevents the exudates absorbed and contained by the absorbent core 10 from wetting the articles that are in contact with the diaper 60 such as sheets and undergarments. Preferably, the backsheet 62 is the polyethylene film having a thickness of about 0.012 millimeters about 0.051 centimeters, although other flexible, liquid impervious materials can be used. As used herein, the term "flexible" refers to materials that are docile and that will readily conform to the outline and general shape of the user's body.

A suitable polyethylene film is manufactured by Monsanto Chemical Corporation and commercially available as Film No. 8020. The backsheet 62 is preferably embossed and / or finished dull to provide a more fabric-like appearance. In addition, backsheet 62 can be "breathable", allowing vapors to escape from absorbent core 10 while still preventing exudates from passing through backsheet 62. A backsheet that is highly breathable but substantially impermeable is contemplated. liquid may be desirable for certain absorbent articles. The size of the backsheet 62 is dictated by the size of the absorbent core 10 and the exact design of the selected diaper. In a preferred embodiment, the backsheet 62 has a modified hourglass shape extending beyond the absorbent core 10 at a minimum distance of at least about 1.3 centimeters to at least about 2.5 centimeters around the total periphery of the diaper. The top sheet 61 and the back sheet 62 are mutually joined in any suitable manner. As used herein, the term "attached" encompasses configurations by which the top sheet 61 is directly attached to the back sheet 62 by attaching the top sheet 61 directly to the back sheet 62, and configurations by which the top sheet 61 is indirectly attached to the backsheet 62 by fixing the top sheet 61 to intermediate members the cases will be fixed to the backsheet 62. In a preferred embodiment, the top sheet 61 and the backsheet 62 are fixed directly to each other in the diaper periphery by attachment means (not shown) such as an adhesive or any other means and attachment as is known in the art. For example, a uniform adhesive layer may be used, continued, a patterned adhesive layer, or an array of separate lines or spots of adhesive to attach the top sheet 61 to the backsheet 62.

The tape tab fasteners 65 are typically applied to the waistband region 63 of the diaper 60 to provide a fastening means for holding the diaper on the wearer. The tape tab fasteners 65 shown are representative only. The tape tab fasteners may be any of those well known in the art, such as the fastener tape disclosed in United States Patent No. 3,848,594 (Buell) issued November 19, 1974, which is incorporated by reference. These tape tab fasteners or other diaper fastening means are typically applied near the corners of the diaper 60. The elastic members 69 are disposed adjacent the periphery of the diaper 60, preferably along each longitudinal edge 64, in shape such that the elastic members tend to stretch and hold the diaper 60 against the user's legs. Additionally, the elastic members 67 may be arranged adjacent to either or both of the waistband regions 63 of the diaper 60 to provide a waistband as well as or instead of the leg cuffs. For example, a suitable waistband is disclosed in U.S. Patent No. 4,515,595 (Kievit et al.) Issued May 7, 1985, which is incorporated by reference. In addition, a method and apparatus suitable for the manufacture of a disposable diaper having elastically shrinkable elastic members is described in U.S. Patent No. 4,081,301 (Buell) issued March 28, 1978, which is incorporated by reference . The resilient members are secured to the diaper 60 in an elastically contractible condition in such a manner in a normally unrestricted configuration, the elastic members effectively contract or collect the diaper 60. The elastic members can be secured in an elastically contractible condition at less two ways. For example, the elastic members can be pulled and secured while the diaper 60 is in an uncontracted condition. Alternatively, the diaper 60 can be contracted, for example, by folding, and the elastic members secured and connected to the diaper 60 while the elastic members are in their non-relaxed or undrawn condition. The elastic members may extend along a portion of the length of the diaper 60. Alternatively, the elastic members may extend the total length of the diaper 60, or any other suitable length to provide an elastically contractible line. The length of the elastic members is dictated by the design of the diaper. In use, the diaper 60 is applied to a wearer by placing a waistband region under the user's back, and pulling the rest of the diaper 60 between the user's legs such that the other waistband region is placed across the front of the diaper. user. The tape tab. 65 or other fastener, are then preferably secured to the outward facing areas of the diaper 60. In use, the disposable diapers or other absorbent articles that it incorporates into the absorbent members of the fluid of the present invention tend to distribute and store liquids more rapidly and efficiently and remain dry due to the high absorbent capacity of the absorbent members of the fluid. Disposable diapers that incorporate the fluid absorbent members of the present invention can also be more delegated and more flexible. When used as an absorbent core in a disposable diaper 60, a preferred embodiment of the core 10 according to the present invention is positioned such that the acquisition / distribution strip 52 is in fluid communication with the top sheet 61, and serves to quickly acquire and separate the exudates from the body of the user body towards the storage / redistribution strips 51 generally more absorbent and the front and rear panels 20 and 30. The adhesive bonding of the acquisition / distribution strip 52 to the top sheet 61 can increase fluid communication by providing the interfacial junction and prevent separation of the top sheet from impeding fluid flow.

The front panel generally corresponds to the part of the disposable diaper worn on the front of the wearer, with the outer front end 21 which is generally close to the wearer's waist area. Similarly, the rear panel 30 corresponds to the part of the disposable diaper worn on the back of the wearer, with the outer rear end 31 which is generally close to the wearer's waist area. The generally rectilinear mid section 50 has a width 53 corresponding to a width suitable for the crotch area 66 of a disposable diaper. Also, the length of the center section 50 can be varied to provide a fit of suitable for various sizes of the wearer. Figure 3 shows a top view of an absorbent core 10 formed as contemplated in an embodiment of the present invention. As shown, the front and rear panels 20 and 30, together with the generally middle section and 50, generally form an elongated hourglass shape suitable for use in a disposable diaper or similar absorbent article. In a preferred embodiment, the width 53 of the generally rectilinear mid section 50 is suitable for comfortably fitting within the crotch area of the wearer when the absorbent core 10 is incorporated within an absorbent article, such as a disposable diaper. The number and placement of the strips 51 or 52 of the generally rectilinear central section 50 can be varied to achieve the desired characteristics such as thinness, softness, flexibility, or coefficients of fluid acquisition, distribution and storage. For example, Figure 4 shows in cross-section an embodiment of the present invention utilizing an acquisition / distribution strip 52 and a storage / redistribution strip 51, both placed on the front and rear panels 20 and 30 of storage / redistribution, resulting in a thin, flexible absorbent core 10. By "on" is meant the side of the absorbent core of the invention which corresponds to the wearer's body when used in an absorbent article such as a catamenial pad or a disposable diaper. It is noted, however, that Figure 4 is representative of only one embodiment, and it may be beneficial to place the strips 51 or 52 under the front and rear panels 20 and 30. "Under" is to be understood as the core side absorbent of the invention corresponding to the garment side when used in an absorbent article such as a catamenial pad or a disposable diaper. Figure 5 shows an alternate absorbent core 10 having two strips 51, 1 placed on the front and rear panels 20 and 30, and the other positioned below the front and rear panels 20 and 30. As shown in figures 4 and 5, and as in the preferred embodiment of the present invention shown in Figures 1 and 3, the acquisition strip 52 is generally on the side corresponding to the body side of an absorbent article, such as a disposable diaper. Therefore, the acquisition / distribution strip 52 is generally in fluid communication with the upper sheet 61 of the disposable diaper, thereby acting to rapidly acquire and distribute body exudates to the lower storage / distribution layers 51 and to the front and rear panels 20 and 30 of storage / redistribution. The number of layers of the front and rear panels 20 or 30 can also be varied to achieve the desired characteristics such as beneficial fluid acquisition and distribution coefficients, as well as capacity and storage coefficients, as well as comfort for the user. For example, Figures 6 and 7 show in cross section additional embodiments corresponding to the general top view of Figure 3. Figure 6 depicts two layers of the front and rear panels 20 and 30, both placed below the center section 50 generally rectilinear. Figure seven shows two layers of the front and rear panels 20 and 30, but in the embodiment shown one layer is placed over the central section 50 generally rectilinear, and one layer is placed underneath, thus "sandwiching" the ends of the panel. central section 50 generally rectilinear.

By forming the absorbent core into sections, I know that they have several desired results. First, the core exhibits desirable aesthetics and fit when used in an absorbent article due to the use of strips or discontinuous panels of absorbent material. For example, when used in absorbent articles such as disposable diapers, the separate strips comprising the center section tend to bend and warp a bit independently of the adjacent strips (and the front and back panels) to provide better fit and comfort in the crotch area that is achieved with absorbent cores in one piece. A second advantage of the core formed in sections is the ability to independently form many of the characteristics of the absorbent members. These variations include the acquisition coefficients, distribution coefficients, capacities and storage coefficients, coefficients and efficiencies of interfacial fluid transfer, thickness, functionality and the shape or configuration of the absorbent strips or panels. For example, in a preferred embodiment of the present invention, the three absorbent strip members comprise in the central section, with the absorbent strip member closer to the user's body having relatively greater acquisition characteristics, and the remaining two having characteristics of relatively larger acquisition / distribution. In this configuration the bodily discharges, such as urine, are rapidly acquired by the acquisition layer from the side to the body and desorbe them towards the adjacent acquisition / distribution layers for distribution towards the front and rear panels which preferably have absorption characteristics. of storage / redistribution. It is contemplated that additional combinations of strip member, placement and absorption characteristics may be utilized, with the requirements of their desired annals influencing the final design without departing from the scope of the present invention. For example, a beneficial configuration of the generally rectilinear central section 50 is to have strips of acquisition component on the side of the core body as well as adjacent to the backsheet. In this configuration fluid that filters or drains to the backsheet can be quickly acquired and distributed to the storage / redistribution components of the absorbent core, thus minimizing the opportunity for fluid leakage.

The Absorbent Materials As described above, the absorbent core 10 comprises a plurality of discrete components, each component capable of having different characteristics of acquisition, acquisition / distribution or storage / redistribution of the fluid. In the context of the present invention, it should be distinguished that the term "fluid" means "liquid". While the acquisition, acquisition / distribution and storage / redistribution components are in fluid communication with each other, they can be placed in relation to one another in a wide variety of configurations. In general, any absorbent material having structural integrity such that it can be processed from a roll material by the method of the present invention can be used as the absorbent core 10 in an absorbent article of the present invention. Particularly preferred absorbent materials for use as the absorbent components are nature-based foam. Polymeric foams that are suitable for use in the fluid acquisition component can generally be characterized as the structures that result when a relatively monomer-free gas or a relatively monomer-free liquid is dispersed as bubbles in a liquid containing monomer polymerizable, followed by the polymerization of the polymerizable monomers in the monomer-containing liquid which surrounds the bubbles. The resulting polymerized dispersion may be in the form of a solidified porous structure that is an aggregate of cells, the boundaries or walls of whose cells comprise polymerized solid material. The cells themselves contain the relatively monomer-free gas or the relatively monomer-free liquid, which, before polymerization, has formed the "bubbles" in the liquid. Absorbent foams particularly suitable for absorbent articles such as diapers have been made from High Internal Phase Emulsions (hereinafter referred to as "EAFI"). See, for example, U.S. Patent No. 5,260,345 issued to DesMarais et al. On December 7, 1993, and U.S. Patent No. 5,563,179 issued to Stone et al. On October 18, 1996, each one of which is hereby incorporated by reference. These EAFI absorbent foams provide the desirable fluid handling properties, including (a) relatively good acquisition coefficients to quickly acquire urine discharges; (b) relatively good capillary action or wicking and fluid distribution characteristics to transport the urine or other body fluid imbibed away from the initial shock zone and toward the unused balance of the foam structure to allow subsequent jets of fluid are accommodated; and (c) a relatively high storage capacity with a fluid capacity under high relative high load, that is, under compressive forces. The absorbent foams of EAFI that are also flexible and soft enough to provide a high degree of comfort to the wearer of the absorbent article; some can be made relatively thin until they are subsequently wetted by absorbed body fluid. See also the aforementioned Patent No. 5,147,345 to Young et al., And U.S. Patent No. 5,318,554 issued to Young et al. On June 7, 1994, which discloses absorbent cores having an acquiring / distributing component. fluid that can be an open cell, flexible, hydrophilic foam, such as a melamine-formaldehyde foam (eg, BASOTECT * made by BASF), and a fluid storage / redistribution component that is an EAFI-based absorbent foam . Representative materials suitable for use with the present invention are not limited to EAFI foams, and will be described in greater detail.

The Acquisition Component An absorbent core element is a fluid acquisition component which comprises a porous absorbent structure having certain fluid handling characteristics with respect to the discharged aqueous body fluids, eg, urine, which pass over and through this structure through of, for example, the top sheet of an absorbent article as described above. Since the fluid that is frequently discharged in jets, the acquisition component must be able to rapidly acquire, temporarily maintain and also preferably transport (or distribute) the fluid, for example, by capillary action or other mechanisms, from the initial point of fluid contact to other parts of the acquisition component for eventual absorption within the adjacent fluid acquisition / distribution or storage / redistribution components. Any porous absorbent material that will imbibe and distribute the body aqueous fluids towards the acquisition / distribution or storage / redistribution components of the core can be used as the acquisition layer 52. A measure of the fluid acquisition effectiveness of the absorbent material used to form the absorbent material. The acquisition component is the Fluid Acquisition Coefficient, by means of which time measurements are taken for the aliquots of the synthetic urine test liquid deposited on the surface of an absorbent material that is absorbed within the internal structure of the material absorbent. Fluid acquisition coefficients and suitable test methods are generally disclosed in the aforementioned patent 5,147,345 to Young et al. Accordingly, the fluid acquisition component must be formed from an absorbent material exhibiting an initial Fluid Acquisition Coefficient of at least about 2 millimeters of synthetic urine per second. More preferably, the fluid acquisition component will comprise an absorbent material exhibiting an initial Fluid Acquisition Coefficient of at least about six millimeters of synthetic urine per second. The "Initial" Fluid Acquisition Coefficient is the time taken for the first aliquot of this test liquid to be absorbed into the absorbent material before the material already contains any of the synthetic urine test liquid. Preferred absorbent materials for the acquisition component include synthetic fiber nonwovens, cellulosic nonwovens, and various synthetic / cellulosic nonwovens. A preferred synthetic nonwoven material is disclosed in the commonly assigned U.S. Patent No. 4,988,345 to Reising, issued January 29, 1991, and U.S. Patent No. 4,988,344 to Reising, issued January 29. of 1991, both of which are hereby incorporated by reference. The Reising acquisition layer comprises a first layer of hydrophilic fibrous material of lower average density than the other parts of the first layer in such a way that it rapidly acquires the discharged liquids. A preferred cellulosic nonwoven suitable for the core acquisition components is formed from cellulose fibers that impart certain wet and dry density characteristics to the absorbent core component. More specifically, the portions or regions of an absorbent core that acquires the discharged body fluids will preferably have a dry average density of less than about 0.30 grams / cm 3, and a density averaged when wetted with an aqueous solution of NaCl, 1.0%, less than about 0.20 grams / cm3, and a dry average basis weight of about 0.001 to about 0.10 grams / cm2. Preferred cellulosic nonwoven materials also comprise from about 50% to 100% twisted and crimped cellulosic fibers, chemically hardened, and from about 0% to about 50% binder media. This cellulosic nonwoven material is disclosed in Young's and other aforementioned patent No. 5,147,345, and commonly assigned U.S. Patent No. 5,531,728 to Lash, issued July 2, 1996, which is hereby incorporated herein by reference. reference. The acquisition layer may be composed of several different materials including synthetic nonwoven webs including polyester, polypropylene or polyethylene, natural fibers including cotton or cellulose, mixtures of these fibers, or any equivalent materials or combinations of materials . Examples of these acquisition materials are more fully described in U.S. Patent No. 4,950,264 to Osborn, issued August 21, 1990, which is hereby incorporated by reference. A suitable thermoplastic binder, including preferable thermoplastic fibers, is disclosed in commonly assigned U.S. Patent No. 5,549,589 to Horney et al., Issued August 27, 1996, which is hereby incorporated by reference. The thermoplastic binder means may include any thermal melt adhesive that can be melted at temperatures that will not excessively damage the cellulose fibers. Once thermally hardened, the resulting nonwoven material exhibits wet / dry mechanical properties such as flexibility, resilience and structural integrity such that it can be processed as a roll material in the method of the present invention. If chemical binding media are used to give structural integrity to the non-woven material, preferably the absorbent member will comprise between about 80% and about 95% of the chemically hardened fibers, about 3% to 20% of a high surface fiber, and from 0% to about 5% of a chemical additive binder medium. A currently preferred chemical additive binder medium is the polyacrylamide glyoxal resin marketed by Cytec Industries, West Patterson, N.J., under the tradename Parez 631 NC. Suitable additional fiber types and the chemical additive agglutinating medium are disclosed in the commonly assigned U.S. Patent Application Serial No. 08 / 633,630 to Seger et al., Filed on April 17, 1996, the disclosure of which is hereby incorporated herein by reference. Other acquisition materials may be prepared by wet laying according to commonly assigned U.S. Patent No. 5,217,445 to Young et al., Issued June 8, 1993, which is hereby incorporated by reference. In general, wet laid webs can be made by depositing an acrylic suspension of fibers on a foraminous forming wire, dehydrating the wet laid suspension to form a wet web, and drying the wet web. Further disclosure of particular wet laying techniques suitable for the formation of an acquisition core component suitable for use of the present invention is disclosed in the above-mentioned patent 5,147,345 to Young. In addition to rapidly acquiring bodily fluids, the absorbent acquisition component of the present invention must efficiently raise this fluid to other fluid acquisition / distribution or storage / redistribution components, including fluid based storage components. of foam. Absorbent foams suitable for use as the acquisition component of the present invention combine relatively high capillary absorption pressures and capacity properties by weight (compared to conventional foams). These foams are disclosed in United States Patent No. 5, 550,167 issued to DesMarais et al. On August 27, 1996, which is hereby incorporated by reference.

The Components of Acquisition / Distribution of Fluid The fluid acquisition / distribution components of the present invention may comprise similar materials as the acquisition component, with greater distribution characteristics. Since the body's aqueous fluid is discharged, for example, urine, it frequently discharges into jets, which the acquisition / distribution component must be able to acquire quickly and must also preferably transport the fluid, for example, by capillary action or wicking effect. or other mechanisms, from the point of initial fluid contact makes other parts of the acquisition / distribution component for eventual absorption towards the adjacent fluid storage / redistribution component. These materials are preferably polymeric foam materials that have a greater degree of dispensing ability so that exudates from the body can be transported more efficiently from the acquisition zone to the storage components of the absorbent core. The absorbent materials comprising the fluid acquisition / distribution component of the articles herein will preferably be suitably effective in transporting the liquid absorbed from one part or region of the acquisition / distribution component to another. The transport of the liquid will often arise by virtue of the tendency of the absorbent material of the acquisition / distribution component to capillary absorb the liquid through its structure. Accordingly, a measure of the effectiveness of the fluid distribution of the absorbent material used to form the acquisition / distribution component relates to the ability of this absorbent material to vertically absorb capillary synthetic urine. The effectiveness of vertical capillary absorption can be measured and quantified in a number of ways, but a typical indicator of vertical capillary absorption performance is the height at which a vertically placed test strip of absorbent material will capillary absorb synthetic urine to from a deposit within a specified period of time. For purposes of the present invention, this height, called Vertical Capillary Absorption Height, is determined by the method described in the above-mentioned patent 5,147,345 to Young et al. The fluid acquisition / distribution component of the articles herein will preferably be formed from the absorbent material exhibiting a Vertical Capillary Absorption Height in 30 minutes of at least about five centimeters. More preferably, the fluid acquisition / distribution component will comprise the absorbent material which has a Vertical Capillary Absorption Height in 30 minutes of at least about 10 centimeters, and most preferably the absorbent material which exhibits a Capillary Absorption Height of 25 centimeters Any porous absorbent material which will imbibe and distribute the body aqueous fluids to the limit set forth hereinbefore can be used in terms of the fluid acquisition coefficient and preferably the vertical capillary absorption height as the, or as part of, the acquisition component. fluid distribution of the absorbent articles herein. Frequently this absorbent material can be of a foamed and / or fiber-based nature. A preferred embodiment uses a polymeric, absorbent, open cell foam material, which, in addition to functioning as an acquisition / distribution component in an absorbent core, has improved desorption properties to allow other core components to have higher absorption pressures. that the desorption pressure of the acquisition / distribution foam to distribute away from the fluid. In particular, the absorbent foams useful in or as the fluid acquisition / distribution component are those having a pore volume of from about two to 100 ml / gram, a specific surface area of capillary deception of from about 0.2 to 1 m2 / gram; a cell size of 10 to 300 microns and a density of approximately 0.01 to 0.5 grams / cm3, provided in a considered manner for these selected parameters such that the absorbent foams exceed the minimum vertical capillary absorption coefficient mentioned above. The concepts of flexibility, hydrophilic capacity, pore volume, capillary suction, specific surface area, cell size and foam density as they are related in the present invention are described in greater detail in the Young Patent 5,147,345 and others, above mentioned, open cell, absorbent polymeric foam materials suitable for use as the acquisition / distribution components in the present invention are described in the aforementioned patent 5,563,179 issued to Stone et al. Other types of non-woven structures suitable for use as the fluid acquisition / distribution component include structures such as carded, secured, surfactant-treated webs, macro-fiber webs and melt-blown synthetic micro fibers, formed webs of pulp , shaped fiber cut frames and the like. If non-woven fibrous absorbent structures are used in the present invention, these webs are preferably constructed essentially from chemically hardened hydrophilic cellulosic fibers. These cellulosic fibers are typically wood pulp fibers which have been hardened with an intrafiber chemical curing agent and processed in another manner such that they are formed into a twisted, curled configuration, as fully taught in the aforementioned patents. No. 5,147,345 to Young et al. And Lash, as well as United States Patent Application Serial No. 08 / 633,630 to Seger et al.

The cellulosic fibers, in addition to being chemically hardened, can also be advantageously combined with fibers of high surface area, such as eucalyptus fibers, as disclosed in the commonly assigned, co-pending, U.S. Patent Application Serial Number 08 / 686,076 to Seger et al., Filed July 24, 1996, the disclosure of which is hereby incorporated by reference. The chemically hardened fibers and eucalyptus fibers can be formed in a stratified manner with the thermoplastic binder or chemical binder, as taught in the aforementioned U.S. Patent Application Serial No. 08 / 686,076 to Seger et al. others.

The Storage Components / Fluid Redistribution The absorbent core of the present invention comprises at least one, and preferably two, different fluid storage / redistribution components. The fluid storage / redistribution components act to store exudates from the body away from the user's body to leave the user feeling dry and to prevent leakage. The storage / redistribution components are maintained in fluid communication with the acquisition or acquisition / distribution layer or layers in such a way that the urine or other aqueous body fluids present in the acquisition / distribution component can be desorbed, being absorbed by the fluid storage / redistribution component or components. The non-woven materials as described above, particularly when combined with particles of hydrogel-forming polymer materials, absorbers, substantially insoluble in water, may be useful as the fluid storage / redistribution component or components.

A preferred fluid storage / redistribution component of the absorbent core comprises adherent sheets made from particles of hydrogel-forming polymer materials, absorbent, substantially insoluble in water. The sheets may be made by layering predetermined amounts of the hydrogel forming materials with crosslinking and curing agents. A preferred material of this type is disclosed in commonly assigned U.S. Patent No. 5,324,561 to Rezai et al., Issued June 28, 1994, which is incorporated herein by reference. The most preferred fluid storage / redistribution component materials of the present invention comprise collapsible polymeric foam materials which, upon contact with aqueous fluids (in particular aqueous body fluids such as urine), can expand and absorb these fluids. . The polymeric foam absorbent materials comprise a non-ionic, flexible, hydrophilic, interconnected open cell polymeric foam structure as disclosed in U.S. Patent No. 5,387,207 issued to Dyer et al. On February 7, 1995, and US patent application serial number 08 / 563,866 entitled absorbent foam materials for aqueous fluids made from high internal phase emulsions having very high water-to-oil ratios, by DesMarais et al., filed on 29 November 1995, both of which are hereby incorporated by reference. In other polymeric absorbent foam materials, the characteristics of the material, and the characterizing tests are disclosed and taught in the aforementioned U.S. Patent No. 5,147,345 to Young et al. The collapsible polymer foam storage / redistribution component of the present invention can utilize low density absorbent foams (when expanded). For a given expanded thickness, these foams with lower density are thinner in their collapsed state than the previous EAFI absorbent foams. These foams with lower density use more efficiently the polymeric material available and as a result provides an economically attractive means to achieve thinner absorbent core for absorbent articles such as diapers, each training zone that is climbed, pads or trusses for adult incontinence, sanitary napkins, and the like. This is achieved while retaining the absorbency, dryness and desired mechanical properties.

The Method and Apparatus for Making the Absorbent Formed Nuclei A preferred method for making the absorbent core formed of the present invention is now described with reference to Figs. 8 to 15. Fig. 8 schematically shows a representative apparatus 70 suitable for carrying out the method of forming the absorbent core components. of the preferred embodiment of the present invention as depicted in Figure 1. The method depicted in Figure 8 and described in detail below can be easily modified to produce absorbent cores comprising different combinations and placements of the absorbent members, such as shown in Figures 4 to 7. The representative modifications are shown schematically in Figures 9, 10 and 11 and, unless otherwise described, can be understood with reference to the description of the method of Figure 8 since similar numbers identify similar elements. The method of the present invention is not limited to non-woven weave materials or absorbent polymeric foam materials, but is suitable for use with any generally absorbent material formed into wefts, whether woven or non-woven, fibrous or polymeric, as is known in the art which can be supplied in roll material and which have sufficient integrity to be processed by the method of the present invention.

A first relatively narrow rectilinear web 81 is unwound from a supply roll 71. The web 81 has a width generally corresponding to the width 53 of the generally rectilinear central section 50, as shown in Figures 1 and 2. The web 81 comprises a material suitable for use as an acquisition / distribution layer 52 of the preferred embodiment as shown in Figures 1 and 2. The frame 81 is guided through the entry point 100 on a conveyor 102 where it is placed for further processing as described below. In a preferred embodiment, the second and third relatively narrow rectilinear webs 82 and 83 are unwound, composed of a material suitable for acquisition / distribution or storage / redistribution of the aqueous fluid, from the supply rolls 72 and 73, respectively. Frames 82 and 83 correspond to the storage / redistribution layers 51 of Figures 1 and 2 and may have a width generally corresponding to the width 53 of the generally rectilinear central section 50, as shown in Figures 1 and 2. The wefts 82 and 83 are guided through the entry point 100 on the conveyor 102 where these are placed in the layers on the frame 81 for further processing as described below. - - A relatively wide continuous rectilinear web 84 of absorbent material having a longitudinal axis and side sides is unwound from a supply roll 74. In a preferred embodiment, the screen 84 is suitable for use as a storage / redistribution member of the absorbent core 10, and is of a suitable width to form in the front panel 20 and the rear panel 30 shown in Figures 1 and 3. The side sides of the frame 84 generally correspond to the sides 23 and 33 shown in the figure 3. The weft 84 is guided from the roll 74 to a notch forming apparatus 90. The notch forming apparatus 90 preferably comprises two inlet rollers 91 and 92 through which the weft 84 is fed as it is fed. the weft 84 through the inlet 93 of the rollers 91 and 92, the cutting blades (not shown) on the roller 91 cut substantially arched portions from the opposite sides of the raster 84 in such a way as the weft 84 leaves the notch forming apparatus 90, this appears as shown in Figure 12. Figure 12 shows the continuous rectilinear pattern 84 with substantially arched notches 120 at spaced intervals 11 corresponding to the positioning of the cutting blades on the roller 91 shown in Figure 6. The continuous rectilinear pattern 84, with the notches as shown in Figure 12, is then fed into a first slide, cut and set assembly 95 to make cross-sectional cuts to the longitudinal axis to divide the rectilinear weft 84 into discrete sections 85, and to separate the discrete sections as shown in figure 13. The screen 84 is guided on the rotating drum 96 which serves as a stage. Once in contact with the surface of the rotary drum 96, and before being cut into discrete sections, the weft 84 is moved at a speed lower than that of the surface of the drum and of the sliding relative to the surface of the drum 96 under the light vacuum applied through the perforations in the surface of the drum along a part of the circumference of the drum. The cutting rollers 97 rotate in accordance with the rotary drum 96, the diameter of the cutting roller 97 being such that a cutting blade 98 attached to the cutting roller 97 intersects the rectilinear pattern 84 at spaced intervals 121 of FIG. 12, forming the discrete sections 85. Once the weft 84 is cut into the discrete sections 85, a somewhat higher vacuum is applied along the parts of the circumference of the drum such that the divided sections 85 remain in contact with the rotating drum 96, moving at the same speed as the drum surface in a separate separate relation. As shown in Figure 13, the discrete sections 85 can best be described as having a generally rectangular shape with slotted corners 40, corresponding to the notches 40 of Figure 1.

The rotary drum 96 is positioned such that when turning, the discrete sections 85 are released due to positive air pressure through the perforations in the drum surface along a portion of the circumference of the drum, and are driven towards contact with the layer 83 moving on the conveyor 102. The vacuum arrangement in the rotating drum 96 is such that in the contact position with the layer 83, the discrete section 85 is released from the rotating drum 96 and continues to be carried by the layer 83 via the conveyor 102. The linear speed of the conveyor 102 is generally equal to the tangential linear velocity of the rotary drum 96, such that the discrete sections 85 are deposited in a spaced relation on the layer 83, as is illustrated in Figure 9. Figure 14 shows in plan view the material that is carried by the conveyor 102 to, for example, point 103 in Figure 8. Layer 83, and the layers 82 and 81 below (not shown), form continuous rectilinear patterns below the discrete sections 85 which is placed in a separate separate relationship. The discrete sections 85 are spaced apart at spaced intervals 130, which generally correspond to the distance of the transverse center lines 131 of the adjacent discrete sections 85. The material that is carried on conveyor 102 is fed to the knife assembly 150 to make transverse cuts that divide all the layers of the material. The cutting roller 152 has a diameter that corresponds generally to the distance between the transverse center lines 131 of the discrete sections 85 as shown in Figure 14. The roller 151 serves as a platen for the cutting blade 153 attached to the platen roller. cutting 152. The cutting blade 153 completely divides the layers at or near the transverse center lines 131 of the discrete sections 85. Upon exiting the knife 150, the absorbent material has been formed in the individual absorbent cores 10 of the present invention. . Various known methods can be used to separate the individual absorbent cores 10, such as by varying the relative speeds of the conveyors 102 and 160. The individual absorbent cores 10 are carried by the conveyor 160 for further processing in the absorbent articles, if necessary, and appear on conveyor 160 in the plan view as shown in Figure 15. As shown in Figure 15, it is not necessary that the length of the front panel 20 be measured from the outer front end 21 to the inner front end 22 to equalize the length of the back panel 30 measured from its outer rear end 31 to its inner rear end 32. The position of the material in layers on the conveyor 102 relative to the knife assembly 150 determines the relative lengths of the front panel 20 and the panel 30, and can be adjusted by the phase of! knife assembly 150 relative to conveyor 102. In a preferred embodiment of the present invention, rear panel 30 is longer than front panel 20 as illustrated in FIG. 15. This configuration tends by itself to better fit when use the absorbent article 10 in a disposable diaper. As shown in Figures 13 and 14, the length of the interval 130 can be varied to produce the desired length of the generally rectilinear mid section 50. It is desirable to be able to vary the length of the center section 50 of an absorbent core. 10 for use in disposable diapers to cover the difference in sizes of children or adults who use these diapers. Figure 9 shows an embodiment of a method and apparatus of the invention as it may be for producing the core illustrated in Figure 5. Instead of a third relatively narrow rectilinear web 83, unwound from the supply roll 73, the straight line The relatively narrow 86 is unwound from the supply roll 76. The web 86 is then guided to form a top layer of the absorbent material on the conveyor 102. The method continues as described above to form the absorbent core illustrated in Figure 5.

Fig. 10 shows a representative method for forming the absorbent core 10 of the present invention as depicted in Fig. 6. In this embodiment, a relatively wide continuous continuous grid 87 of the absorbent material having a longitudinal axis and lateral sides that is unwinds from a supply roll 77 and is guided to contact and in alignment with the web 84 before entering the notch former 90. the webs 84 and 87 may be mutually adhered by known methods to facilitate proper alignment throughout the remainder of the process, particularly after being processed by the sliding and cutting assembly 95. Figure 11 illustrates a representative method for forming the absorbent core 10 of the present invention as illustrated in Figure 7. In this embodiment of! In this method, a relatively wide continuous continuous rectilinear web 88 is unwound from a supply roll 78. The web 88 is guided from the roll 88 to an apparatus formed of notches 200 which operates in the same manner as the notch forming apparatus 90 described above. . The notch forming apparatus 200 preferably comprises two input rollers 201 and 202 through which the web 88 is fed. As the web 88 is fed through the space 203 of the rollers 201 and 202, the webs cut (not shown) on the roll 00 1 which cut substantially arcuate portions of the opposite sides of the weft 88 in such a manner as the weft 88 leaves the notch forming apparatus 200, are generally similar to the weft 84 as shown in FIG. Figure 12 shows. The continuous rectilinear pattern 88, generally slotted as shown in Figure 12, is then fed to a second slide, cut and set assembly 205 to make cuts transverse to the longitudinal axis that section and separate the rectilinear weft 88 in FIG. discrete sections 210, generally similar to the discrete sections 85 as shown in Figure 13. The screen 88 is guided on the rotating drum 206 which serves as or a stage. Once in contact with the surface of the rotating drum 206, the weft 88 is moved at a speed less than that of the drum surface and slides relative to the surface of the drum 206 under light vacuum applied through the perforations in the surface of the drum. Once the web 88 is cut into discrete sections 210, a somewhat larger vacuum is applied such that the separate sections 210 remain in contact with the rotating drum 206, moving at the same speed as the surface of the drum in a ratio separate apart. The cutting roller 207 rotates in accordance with the rotary drum 206, the diameter of the cutting roller 207 being such that a cutting knife 208 attached to the cutting roller 207 cuts the rectilinear weft 88 at spaced intervals analogously to the spaced intervals 121 of Figure 12, forming the discrete sections 210. The discrete sections 210 may be better described with generally rectangular shaped edge with slotted corners, corresponding to the notches 40 of Figure 13. The rotating drum 206 is positioned such that when turning , the discrete sections 210 are brought into contact with the conveyor 102. The vacuum arrangement in the rotary drum 206 is such that in the contact position with the conveyor 102, the discrete section 210 is released by the positive air pressure of the drum revolving 206 and continuing to be carried on conveyor 102. Speed line! of the conveyor 102 is generally equal to the tangential linear velocity of the rotating drum 206, such that the discrete sections 85 are deposited in a spaced relationship on the conveyor 102, as illustrated in FIG. 11. The remainder of the manufacturing method is as described above. The method of the present invention provides a number of significant benefits. For example, the method generates significantly less waste than a method of forming an absorbent core formed of a part would generate. Also, the method of the present invention provides the efficient supply of wefts of absorbent materials from roll material, especially foam, from which the panels and rectilinear strips are made. An advantage of this process in a long life of the weft roll. For example, the narrower webs of the absorbent material used to make the rectilinear strips can be rolled up on reel for the duration of the roll significantly longer. A third benefit of the method of the present invention is the greater control over certain process variables, such as placement of the core components in the proper operating relationship. For example, because the wider web of the absorbent material is slotted and divided at the point of the front and back panels, it is significantly easier to match the slotted / spaced panels in the proper relationship with the narrower straight strip (s) to form the composite absorbent core. Although the particular embodiments of the present invention have been illustrated and described, it would 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 present invention. The foregoing is, therefore, intended to protect in the appended claims all these changes and modifications that are within the scope of the present invention.

Claims (10)

1. A formed absorbent core comprising at least one layer of fluid absorbent material, preferably an open cell polymeric foam material, said one absorbent core further comprising a front panel having an inner front end and an outer front end; a rear panel having an internal rear end and an external rear end; and a central section having first and second ends; the absorbent core being characterized by: (a) the outer front end having a length and said inner front end having a length less than the length of the outer front end; (b) said outer rear end having a length and said inner rear end having a length less than the length of the outer rear end; (c) the rear panel being positioned such that the inner rear end is opposite the internal front end of the front panel; and (d) said first end of the central section being in fluid communication with the front panel by overlapping the intermediate front panel to the inner and outer front ends, the second end being in fluid communication with the rear panel by overlapping the panel posterior intermediate to the posterior internal and external ends. An absorbent core formed in accordance with claim 1, further characterized in that the front panel comprises first and second sides, each of said first and second sides are joined to the inner front end by an edge defining a notch, preferably a notch. notched generally arched. An absorbent core formed in accordance with claims 1 or 2, further characterized in that the rear panel comprises first and second sides, each of said first and second sides connecting said inner rear end by the edges defining a notch, preferably a generally arched notch. An absorbent core formed in accordance with any of the preceding claims, further characterized in that the central section exhibits fluid acquisition properties in a fluid acquisition region and the front and rear panels exhibit substantially fluid storage properties in the regions of fluid storage, such that fluid can be distributed from the fluid acquisition regions to the fluid storage regions. An absorbent core formed in accordance with any of the preceding claims, further characterized in that the central section comprises at least one, and preferably at least two, absorbent strip members generally rectilinear. An absorbent core formed in accordance with any of the preceding claims, further characterized in that the inner front end and the outer front end define a length of the front panel and the inner rear end and the outer rear end define a length of the rear panel, such that the length of the front panel is preferably substantially equal to, and more preferably less than, the length of the back panel. An absorbent core formed in accordance with any of the preceding claims, further characterized in that the central section terminates substantially concurrently with the outer front end of the front panel, and said second end of the central section terminates substantially concurrently with the external rear end of the rear panel. 8. An absorbent article, preferably a disposable diaper, capable of acquiring, distributing and storing body fluids, said absorbent article having a backsheet and an absorbent core disposed adjacent to the backsheet, said absorbent core comprising at least one layer of absorbent material. fluid absorbing material, preferably an open cell polymeric foam material, said absorbent core further comprising a front panel having an inner front end and an outer front end; a rear panel having an internal rear end and an external rear end; and a central section having first and second ends; the absorbent core being characterized by: (a) the outer front end having a length and said inner front end having a length less than the length of the outer front end; (b) said outer rear end having a length and said inner rear end having a length less than the length of the outer rear end; (c) the rear panel being positioned such that the inner rear end is opposite the internal front end of the front panel; and (d) said first end of the central section being in fluid communication with the front panel by overlapping the intermediate front panel to the inner and outer front ends, the second end being in fluid communication with the rear panel by overlapping the panel posterior intermediate to the posterior internal and external ends. A method for preparing an absorbent core formed, the method being characterized by the steps of: (a) providing at least one and preferably at least two continuous rectilinear webs of the first absorbent material having a first longitudinal axis and a pair of lateral edges that define a first width; (b) forming opposing grooved areas at the side edges of the continuous rectilinear web of the first absorbent material at spaced intervals; (c) sectioning the continuous rectilinear web of the first absorbent material transversely along a line intersecting the generally arcuate grooved areas opposite in spaced intervals to form sections having opposite slotted ends; (d) separating the sections having the opposite slotted ends; (e) providing at least one and preferably at least two continuous rectilinear webs of the second absorbent material having a second longitudinal axis and a pair of side edges defining a second width; (f) superimposing the continuous rectilinear web of second absorbent material in layered relationship with the continuous rectilinear web of the first absorbent material such that the first and second longitudinal axes are substantially parallel; and (g) separating the layers of the absorbent materials transversely at an intermediate point to the slotted ends. A method according to claim 9, further characterized by the step of adhesively bonding the continuous rectilinear web of the first absorbent material and the continuous rectilinear web of the second absorbent material after they are superimposed on the layer relationship and before separating. said layers. SUMMARY Disclosed is a formed absorbent core suitable for absorbing and retaining aqueous body fluids. The absorbent cores comprise a front panel and a back panel. The front and rear panels are made of a fluid absorbing material, and each has an inner end, and an outer end, and two sides. The inner and outer ends of each front and back panel have a length, with the inner end of each being shorter than the external length of each. The front and rear panels may comprise multiple layers of absorbent material. The absorbent cores also comprise a central section made of fluid absorbent material having first and second ends. The first end of the central section is in fluid communication with the front panel by overlapping the front panel between the inner and outer front ends, and the second end which is in fluid communication with the rear panel by overlapping the rear panel between the internal and external posterior ends. A method for preparing an absorbent core formed comprises the steps of providing at least one continuous rectilinear web of the first absorbent material having a first longitudinal axis and a pair of side edges defining a first width. A continuous rectilinear pattern of the second absorbent material having a second longitudinal axis and a pair of lateral edges defining a second width wider than the first width of the first absorbent material is formed with generally arcuate, grooved, opposite areas on the side edges at intervals spaced along the weft of the second absorbent material. The web of the second absorbent material is cross-sectioned along a line intersecting the generally arcuate grooved areas opposite at spaced intervals to form sections having opposite slotted ends. The sections are then placed in such a manner that the slotted ends are spaced apart and overlap the continuous rectilinear web of the first absorbent material, forming layers of the absorbent material. Then the layers of the absorbent material are cut transversely at an intermediate point to the slotted ends.