WO1991010416A1

WO1991010416A1 - Absorbent structure

Info

Publication number: WO1991010416A1
Application number: PCT/US1991/000059
Authority: WO
Inventors: Heinz A. Pieniak; Gloria Huffman
Original assignee: Weyerhaeuser Company
Priority date: 1990-01-16
Filing date: 1991-01-03
Publication date: 1991-07-25

Abstract

Absorbent panel structures for use in disposable diapers. The absorbent panel structures (14) comprise a bulk layer (18) and a compressed composite absorbent layer (16). The compressed composite absorbent layer (16) having a resilient fibrous web (30) containing at least about 200 percent superabsorbent material (32) by weight of the fibrous web distributed therein and a wicking layer (34) of densified hydrophilic fibers. The compressed composite absorbent layer (16) is located at a front portion of the panel (14) that comprises from about 40 percent to about 80 percent of the length of the panel.

Description

ABSORBENT STRUCTURE Field Of The Invention

The present invention relates to new and improved superabsorbent material containing absorbent structures for use in a disposable diaper or the like, that efficiently utilize the superabsorbent material disposed therein in a cost effective manner. Background Of The Invention

Disposable absorbent products have been known for some time, including such products as disposable diapers, sanitary wound dressings, bandages, incontinent pads, and the like. These products incorporate an absorbent batt or panel that is used to absorb and hold or contain body fluids. In years past, in many of these products, especially diapers and sanitary napkins, the absorbent batt comprised what is termed "wadding" or plies of tissue. The wadding was disposed between an impermeable backing sheet and a permeable facing sheet and the plies of tissue were used to absorb and contain the liquid within the product.

The wadding type of batt was replaced, for the most part, by an improved absorbent batt comprised of fluffed wood pulp fibers. This absorbent batt comprises a layer of individualized wood pulp fibers with the layer having substantial thickness. This diaper has improved absorbent capacity and has somewhat better containment than a diaper using a wadding layer. Also the fluffed wood pulp layer is quite soft, flexible and conformable and hence, produces an improved diaper over diapers using wadding as the absorbent layer.

Though the fluffed wood pulp absorbent batts have improved capacity, the efficiency with which the capacity is used in a diaper is poor. The reason for this, is that the fluid to be absorbed is generally deposited in a localized or a target area within the absorbent batt and the ability for the fluid to wick along the plane of the batt is poor. The fluid follows the path of least resistance and consequently moves to the closest edge of the batt where it generally is no longer contained and the product leaks. Furthermore, the wood pulp batts lack stability, e.g., when a diaper is being worn, the batt tends to sag and/or break up thereby creating bunching.

U.S. Pat. No. 3,017,304 discloses an absorbent product which incorporates in the product a densified, paper-like layer. This paper-like layer acts as a wick, i.e., liquid which contacts the layer tends to move rapidly along the plane of the layer. When incorporated in combination with fluffed wood pulp fiber, the resultant product uses the absorbent capacity of the fluffed wood pulp much more efficiently. Diapers which incorporate this paperlike layer combined with fluffed wood pulp are disclosed and described in U.S. Pat. Nos. 3,612,055 and 3,938,522. Even though these products make much greater use of the capacity of the absorbent batt, they still do not totally contain the absorbed liquid.

A number of years ago "superabsorbent materials", i.e., materials which will absorb many times their weight of liquid, were developed. Since the development of such materials, various different approaches have been suggested to incorporate them in absorbent products such as diapers to enhance the absorptive performance of these products. Perhaps one of the first proposals to incorporate such a superabsorbent material in a disposable diaper is disclosed in U.S. Pat. No. 3,670,731. This patent discloses an absorbent dressing comprising an absorbent layer sandwiched between a permeable facing and an impermeable backing sheet. The absorbent layer contains water insoluble cross-linked hydrocolloid polymer as the superabsorbent material.

In order for a superabsorbent material to function, the liquid being absorbed must be transported to the superabsorbent material. In other words, the superabsorbent material must be placed in a position to be contacted by the liquid discharged onto the absorbent body. Furthermore, as the superabsorbent material absorbs the liquid, it must be allowed to swell. If the superabsorbent is prevented from swelling, it will cease absorbing liquid. Hence, if the superabsorbent material is to function in diapers wherein the liquid to be absorbed is discharged in a small void area, the structure of the absorbent layer containing superabsorbent materials appears to be critical. Over the years a number of techniques have been disclosed in an attempt to provide structures which make efficient use of the superabsorbent material. Such products are typified by those disclosed in U.S. Pat. Nos. 4,103,062, 4,102,340, and 4,235,237. In addition, methods for incorporating superabsorbents into suitable layers or suitable configurations which can be placed in an absorbent product have been proposed, and examples of such proposals are disclosed in U.S. Pat. Nos. 4,186,165, 4,340,057 and 4,364,992.

In United Kingdom Patent Specification No. 1,406,615, published on September 17, 1975, an absorbent pad for use in a disposable diaper is disclosed that includes a wood pulp batt of substantially uniform thickness having a gelling agent or superabsorbent material impregnated in one part (target area) of the batt to the exclusion of, or to a greater extent than in, another part of the batt. In accordance with a preferred embodiment, the superabsorbent material is impregnated in a central area of the pad where it is most effective rather than spreading the material evenly throughout the pad area which is deemed to be uneconomical. The weight of the superabsorbent material in the central area is disclosed as being between 20 percent to 100 percent of the weight of the pad in the central area before impregnation.

In United States Pat. No. 3,661,154, an absorbent structure for use in a disposable diaper is disclosed that includes a layer of a blend of cellulose fibers and superabsorbent material. The superabsorbent material concentration is disclosed as being about 1 to 50 parts per 100 parts of cellulose fibers. In accordance with a disclosed embodiment, an additional layer of the cellulose fibers or a layer of a blend of cellulose fibers and superabsorbent material is superimposed on the base layer. This additional layer may be narrower than the base layer and it may be disposed along the central portion of the diaper at the area most likely to be wetted (target area) . The additional layer may be the same thickness as, or thicker or thinner than, the base layer.

In U.S. Pat. No. 4,381,782, an absorbent panel is disclosed that includes a web or batt of a low- density, highly absorbent filler material, such as fluff, to which superabsorbent material is incorporated thereinto in a central area near the front edge of the panel. The side portions of the panel are cut and folded over the central area of the panel.

More recently, other very similar absorbent structures that are directed to making efficient use of the superabsorbent material are disclosed in U.S. Pat. NOS. 4,699,619, 4,673,402 and 4,685,915. In U.S. Pat. No. 4,699,619 various absorbent structure embodiments are disclosed which comprise at least two layers of cellulosic fibers of different densities, with the higher density layer lying beneath a back portion of the lower density layer. In certain embodiments a layer of superabsorbent material is located beneath the higher density layer. In U.S. Pat. No. 4,673,402 an absorbent structure is disclosed that includes an upper layer of essentially hydrophilic fiber material and a lower layer of a substantially uniform combination of hydrophilic fiber material and discrete particles of substantially water-insoluble hydrogel material. The lower layer is positioned such that at least about 75% of the hydrogel material in the lower layer is found within the front two-thirds section of the absorbent structure and such that at least about 55% of the total hydrogel material in the lower layer is found within the front half section of the absorbent structure. In U.S. Pat. No. 4,685,915 an absorbent structure is disclosed that includes a layer of cellulosic fibers which is so disposed that the central portion has a greater average density per unit area and a greater average basis weight per unit area than each of the end portions. Hydrogel particles may be either uniformly dispersed or may be dispersed primarily or only in the central portion of the absorbent structure.

In United States Pat. Nos. 4,500,315, 4,537,590, 4,540,454, 4,573,988, 4,596,567 and 4,605,402 particularly useful compressed composite absorbent products are disclosed that include superabsorbent materials and which utilize a substantial portion of the absorptive capacity of such superabsorbent materials. These products include a nonwoven fibrous web, such as polyester, which has associated with it at least 200 percent by weight of superabsorbent material to form an absorbing layer. In such products, in order to provide a product which will not only absorb liquid but also transport liquid, a wicking layer of wood pulp fibers or other suitable wicking materials are formed in a layer on at least one side of the absorbing layer. The product is then compressed to yield a relatively thin, absorbing product with very substantial liquid absorbing capacity. The resulting compressed composite product is quite stiff, and hence it is preferred to soften the product to provide enhanced flexibility for utilization in products such as disposable diapers and the like. One method of reducing the stiffness of these products is to subject them to microcorrugating and then to perf- embossing to reduce the Taber stiffness value, in the manner as described in U.S. Pat. No. 4,605,402. Absorbent panels for use in a disposable diaper are disclosed which include a full length compressed composite layer and one or more additional compressed composite layers which are placed only in the front portion of the panel to enhance the absorptive capacity of the front portion of the panel.

The present invention provides a new and improved absorbent panel structure for use in a disposable diaper, or the like, that provides efficient utilization of the absorptive capacity of a superabsorbent containing compressed composite layer in a cost effective manner. Summary Of The Invention

The absorbent panel structures in accordance with the present invention include a compressed composite absorbent layer that is located at a front portion of the panel that comprises from about 40 to about 80 percent of the length of the panel. A bulk layer is located at least in the rear portion of the panel that does not have the compressed composite layer. The bulk layer may be made from hydrophilic fibers, hydrophobic fibers and/or a foam material. The compressed composite absorbent layer comprises a fibrous web and a wicking layer. The fibrous web contains from about 200 to about 1500 percent, by dry weight basis of the fibrous material in the web, of superabsorbent material disposed in amongst the fibers of the web. The wicking layer is formed of suitable wicking materials such as wood pulp fibers and is placed on one or both surfaces of the fibrous web and these layers are compressed to yield a compressed composite structure. The fibrous web is maintained in a compressed state by the superabsorbent material, whereupon wetting of the absorbent matrix wets the superabsorbent material so that the fibrous web expands from its compressed state due to the inherent resilience of the web, thereby facilitating swelling of the superabsorbent material.

The disposable diaper embodying the absorbent panel structure of the invention includes a moisture- pervious facing layer or sheet positioned in overlying relationship on one side of the panel. The facing sheet is adopted for positioning adjacent the wearer of the diaper, and may typically comprise non-woven fabric or the like. A backing layer or sheet is positioned on the side of the absorbent panel opposite the facing layer. The backing sheet may be formed from moisture-impervious plastic sheet material. The resulting diaper is light in weight, comfortable to the wearer and economic to manufacture.

In accordance with alternative embodiments of the invention, the bulk layer may extend over the entire length of the absorbent panel or a rear portion thereof and the compressed composite layer may be either positioned above, below, or forward of the front portion of the bulk layer. The compressed composite layer may have wicking layers of substantially equal basis weights or may have wicking layers wherein the wicking layer adjacent the bulk layer may be either of greater or a lesser basis weight than that of the other wicking layer. In accordance with other alternative embodiments of the invention, the compressed composite absorbent layer and the bulk layer are positioned adjacent one another in substantially an end to end relationship. The inner end portion of the bulk layer may abut, extend over, or extend below the inner end portion of the compressed composite layer. The compressed composite absorbent layer may further comprise a plurality of spaced apart longitudinal segments that are positioned either above or below the front portion of the bulk layer. In an additional preferred embodiment of the invention, the front portion of the bulk layer is compressed to reduce its thickness and the compressed absorbent layer is received in the reduced thickness front portion. A cushion web layer is preferably provided between the absorbent panel and the facing sheet. The cushion web layer may extend the entire length of the absorbent panel or extend only above the front portion of the absorbent panel. A tissue layer is preferably wrapped around at least a portion of the bulk layer. Brief Description Of The Drawings

FIG. 1 is a perspective view of a disposable diaper as completely assembled including an absorbent panel structure constructed in accordance with the principles of the present invention;

FIG. 2 is a perspective view of the diaper shown in FIG. 1 in an unfolded condition showing the top side thereof;

FIG. 3 is a cross-sectional view taken along line 3-3 of FIG. 2; FIG. 4A is a top plan view of a first preferred embodiment of an absorbent panel structure in accordance with the invention

FIG. 4B is a cross-sectional view taken along line 4B-4B of FIG. 4A;

FIG. 5A is a top plan view of a second preferred embodiment of an absorbent panel structure in accordance with the invention;

FIG. 5B is a cross-sectional view taken along line 5B-5B of FIG. 5A;

FIG. 6A is a top plan view of a third preferred embodiment of an absorbent panel structure in accordance with the invention;

FIG. 6B is a cross-sectional view taken along line 6B-6B of FIG. 6A;

FIG. 7A is a top plan view of a fourth preferred embodiment of an absorbent panel structure in accordance with the invention;

FIG. 7B is a cross-sectional view taken along line 7B-7B of FIG. 7A;

FIG. 8A is a top plan view of a fifth preferred embodiment of an absorbent panel structure in accordance with the invention;

FIG. 8B is a cross-sectional view taken along line 8B-8B of FIG. 8A;

FIG. 9A is a top plan view of a sixth preferred embodiment of an absorbent panel structure in accordance with the invention;

FIG. 9B is a cross-sectional view taken along line 9B-9B of FIG. 9A;

FIG. 10A is a top plan view of a seventh preferred embodiment of an absorbent panel structure in accordance with the invention;

FIG. 10B is a cross-sectional view taken along line 10B-10B of FIG. 10A; FIG. 11A is a top plan view of an eighth preferred embodiment of an absorbent panel structure in accordance with the invention;

FIG. 11B is a cross-sectional view taken along line 11B-11B of FIG. 11A;

FIG. 12A is a top plan view of a ninth preferred embodiment of an absorbent panel structure in accordance with the invention;

FIG. 12B is a cross-sectional view taken along line 12B-12B of FIG. 12A;

FIG. 13A is a top plan view of a tenth preferred embodiment of an absorbent panel structure in accordance with the invention;

FIG. 13B is a cross-sectional view taken along line 13B-13B of FIG. 13A;

FIG. 14A is a top plan view of an eleventh preferred embodiment of an absorbent panel structure in accordance with the invention;

FIG. 14B is a cross-sectional view taken along line 14B-14B of FIG. 14A;

FIG. 15A is a top plan view of a twelfth preferred embodiment of an absorbent panel structure in accordance with the invention;

FIG. 15B is a cross-sectional view taken along line 15B-15B of FIG. 15A;

FIG. 16A is a top plan view of a thirteenth preferred embodiment of an absorbent panel structure in accordance with the invention;

FIG. 16B is a cross-sectional view taken along line 16B-16B of FIG. 16A;

FIG. 17 is an exploded perspective view of the component layers of a fourteenth preferred embodiments of an absorbent panel structure in accordance with the invention; FIG. 18 is a top plan view of the assembled absorbent panel structure shown in FIG. 17;

FIG. 19 is an end view taken along line 19-19 of FIG. 18; FIG. 20 is a top plan view of the component layers of a fifteenth preferred embodiment of an absorbent panel structure in accordance with the invention;

FIG. 21 is a is a top plan view of the assembled absorbent panel structure shown in FIG. 20;

FIG. 22 is an end view taken along line 22-22 of FIG. 21.

FIG. 23 is an enlarged cross-sectional view of the compressed composite layer prior to compression thereof; and

FIG. 24 is an enlarged cross-sectional view of the compressed composite layer after compression thereof.

Detailed Description of Preferred Embodiments While the present invention is susceptible of embodiment in various forms, there is shown in the drawings and will hereinafter be described various presently preferred embodiments of the invention, with the understanding that the present disclosure is to be considered as an exemplification of the invention, and is not intended to limit the invention to the specific embodiments illustrated and described herein.

As used in the present disclosure, the term diaper is intended to refer to an absorbent article that is worn by an individual for absorbing and containing urine and/or fecal matter. It is to be understood that diapers embodying the principles of the present invention may be appropriately sized for use by infants and can further be sized for use by incontinent adults. Referring now to the drawings, therein is illustrated in FIGS. 1-3 an exemplary disposable diaper 10 embodying an absorbent panel in accordance with the principles of the present invention. Diaper 10 includes a facing layer or top sheet 12 formed of moisture pervious material, with the facing layer being adapted for positioning adjacent to the wearer of the diaper. The diaper further includes an absorbent panel structure 14, which in the illustrated embodiment, is generally rectangular, but which may be otherwise shaped, such as hourglass-shaped, T-shaped, l-shaped, or otherwise contoured. As will be further described, absorbent panel structure 14 in accordance with the invention preferably comprises a compressed composite absorbent structure or layer 16, containing an absorbent matrix of a resilient fibrous web with hydrocolloid or superabsorbent material distributed therein, with an associated wicking layer of densified cellulosic fibers provided on one or both of the expansive surfaces of the fibrous web for enhancing liquid transport within the absorbent matrix, and a bulk layer 18.

Disposable diaper 10 further includes a backing sheet 20 positioned on the side of the absorbent panel structure 14 which is opposite the facing layer 12. The backing sheet typically comprises a moisture- impervious material, such as plastic film or sheet.

Diaper 10 may be provided with a double standing gather 22 consisting of an inner gather 24 and outer gather 26. Double standing gather 22 is preferably formed at the leg openings from a sheet of non-woven hydrophobic material 23 having vapor permeability characteristics, e.g. a fibrous non-woven fabric treated with silicone resin. Inner gather 24 is preferably elasticized by a monofilament rubber element 28 extending the length thereof and outer gather 26 is preferably elasticized by a folded polyurethane foam elastic material 29 extending the length thereof. Sheet 23 is preferably glued to backing sheet 20 by lines of hot melt adhesive.

As will be recognized by those familiar with the art, several different types of facing materials may be used for facing layer 12. For example, these layers may comprise a non-woven web made of a mixture of fibers consisting predominantly of inexpensive, short, cellulosic fibers, such as wood pulp fibers or cotton linters, with the remainder of the mixture being textile length fibers. The non-woven webs may also be formed from polyester, polyethylene, polypropylene, nylon, rayon, or the like. The facing layer may be a laminate of one or more non-woven fabrics, each having differing physical properties. The facing layer may further be apertured.

In order to secure the diaper in position, adhesive tape fasteners 31, as are well known in the art, are provided on the rearward portions of the diaper. Each of these fasteners 31 include a tab-like element having pressure-sensitive adhesive thereon which, when brought into contact with a landing area associated with the forward, outer waist portion of the diaper, secures the diaper in position. The diaper may also be provided with elasticized waistbands 33, as are well known in the art.

In order to reduce the thickness and cost of the diaper and to improve fit and application of the diaper, it is desirable to provide a diaper that minimizes the use of the relatively expensive superabsorbent material and yet still possesses the necessary absorptive capacity. The present invention is particularly directed to various absorbent panel structures for use in a diaper construction that possess these characteristics. The various absorbent panel embodiments of the invention include a compressed composite absorbent layer 16 located at a front portion of the absorbent panel. The compressed composite absorbent layer 16 is preferably made substantially in the manner as disclosed in U.S. Pat. NOS. 4,500,315, 4,537,590, 4,540,454, 4,573,998, 4,596,567, and 4,605,402, the disclosure of which patents are incorporated herein by reference. Referring to FIG. 23, the compressed composite absorbent layer 16 comprises a substantially high loft, resilient fibrous web 30 with superabsorbent material 32 distributed within the fibrous web. The superabsorbent material is preferably in the form of a plurality of particles or globules of superabsorbent material disposed in a random and intermittent arrangement throughout the fibrous web. The particles or globules are of a size and spacing so that they do not interfere with the absorption of liquid by adjacent particles upon expansion of the resilient fibrous web 30. The compressed composite layer 16 further includes liquid transport means in operative association with the absorbent fibrous web 30. The transport mechanism comprises at least one wicking layer 34 of densified hydrophilic fibers, with the wicking layer being coextensive with at least a portion of a respective expansive surface of the fibrous web layer of the absorbent matrix. Notably, this arrangement has been found to provide a very efficient absorbent structure, in that the densified wicking layer promotes liquid transport from a point of introduction to various portions of the associated fibrous web and superabsorbent. One of the problems typically encountered in employing superabsorbent materials in absorbent articles is the fact that such superabsorbents typically do not .transport or wick liquid effectively, but rather can exhibit "gel blocking" upon wetting which can inhibit liquid transport through the material. Thus, the wicking layer(s) of the compressed composite layer desirably promotes liquid transport for efficient utilization of the superabsorbent.

The fibrous web 30 is preferably formed from synthetic staple fibers, such as polyethylene, polypropylene, polyester, nylon, bicomponent fibers, and the like. Melt blown fibrous webs also are suitable. Generally, the fibers are air-laid or melt blown to form a web which, if needed, is then stabilized. Stabilization may be achieved by heat-through bonding, adhesive bonding, point embossing with heat or adhesive, and the like. The stabilization process is selected according to the fibers used and the process used to form the web. Suitable procedures for forming a web include carding, wet-laying, air-laying, or combinations of these, melt blowing and other suitable known techniques. The fibrous web preferably has a dry bulk of at least 20 cc/gm and a wet bulk of at least about 30 cc/gm. The fibrous web generally has a basis weight less than about 4 oz/yd², most preferably about 1.33 oz/yd².

The superabsorbent material 32 present in an intermittently dispersed form in the absorbing web 30 is generally a water-insoluble but water-swellable polymeric substance capable of absorbing water in an amount which is at least 10 times the weight of the substance in its dry form. The superabsorbent material is in the form of particles which may be in the shape of fibers, spheres, bits of film, globules, or the like, or may be applied in the form of a liquid monomer solution which is subsequently polymerized. Generally, the polymerized monomer solution provides globules and bits of film-like particles in the structure. In one type of superabsorbent material, the particles or fibers may be described chemically as having a backbone of natural or synthetic polymers with hydrophilic groups or polymers containing hydrophilic groups being chemically bonded to the backbone or an intimate admixture therewith. Included in this class of materials are such modified natural and regenerated polymers as polysaccharides including, for example, cellulose and starch and regenerated cellulose which are modified being carboxyalkylated, phosphonoalkylated, sulphoalkylated or phosphorylated to render them highly hydrophilic. Such modified polymers may also be crosslinked to improve their water-insolubility.

These same polysaccharides may also serve, for example, as the backbone onto which other polymer moieties may be bonded by graft copolymerization techniques. Such grafted polysaccharides and their method of manufacture are described in U.S. Pat. No. 4,105,033 to Chatterjee et al. and may be described as polysaccharide chains having grafted thereon a hydrophilic chain. The preferred hydrophilic chains are hydrolyzed polyacrylonitrile chains and copolymers of polyacrylamide and polysodium arylate. In addition to modified natural and regenerated polymers, the hydrocolloid particle component may comprise wholly synthetic hydrophilic particles. Examples of those now known in the art are polyacrylonitrile fibers which may be modified by grafting moieties thereon such as polyvinyl alcohol chains, polyvinyl alcohol itself, hydrophilic polyurethane, poly(alkyl phosphonates) , partially hydrolyzed polyacrylamides (e.g., poly (N-N- dimethyl acrylamide) , sulfonated polystyrene, or a class of poly(alkylene oxide). These highly hydrophilic synthetic polymers may be modified by other chemical treatments such as cross-linking or hydrolysis. Further - .

17 examples known in the art are the non-ionic hydrophilic polymers such as polyoxyethylene, poloxypropylene and mixtures thereof which have been suitably cross-linked, either chemically or by irradiation. Still another more recent type is a derivative of isobutylene-maleic anhydride copolymer.

Hydrophilic polymers formed from water-soluble acrylate monomers, such as sodium, potassium, ammonium (or combination of cations) , acrylate, may be placed on the absorbing layer by spraying or otherwise placing a solution thereon followed by polymerization and cross- linking, for example, by irradiation.

In addition, naturally occurring material such as gums, may be used. For instance, guar gum is suitable.

The superabsorbent material 32 is combined with the fibrous web 30 by means suitable to distribute the superabsorbent materials therein trying to minimize interference by one superabsorbent material with another upon the swelling of the first. If the superabsorbent material is a powder, it may be sprinkled onto the fibrous web either in dry form or the web may be moistened. If the superabsorbent is in granular form, it may be desirable to slightly moisten the superabsorbent before placing it in contact with the web. The superabsorbent material will contain particles which range in size from about 0.005 mm in diameter to globules that are continuous along fibers for a distance up to several inches. Another method of placing the superabsorbent material in the web is spraying a monomer solution on the web or saturating the web with a monomer solution followed by polymerization of the monomer. One typical way to polymerize the monomer is by use of irradiation. It is desirable to place the superabsorbent somewhat evenly throughout the fibrous web. However, even if the superabsorbent is powderlike and in the form of a layer, it tends to function better than such a layer has in previously known products. It may be desirable to place more superabsorbent in one area than in another and/or to place the superabsorbent in the structure in predetermined patterns. Any superabsorbent which absorbs large amounts of liquids is suitable for use in the absorbing layer of the present invention. In accordance with a most preferred embodiment of the invention, droplets of the superabsorbent material are dispersed within the web by moving the web through a droplet-flicking zone and flicking droplets of the superabsorbent material, in a liquid carrier, onto opposite sides of the web as the web is moved through the droplet-flicking zone. On each of opposite sides of the fibrous web, a rotating brush has bristles, picking up the material, in the liquid carrier, and flicking droplets thereof as the brush rotates. The superabsorbent material is polymerized and cross-linked in situ. This method is fully disclosed in U.S. Patent Application Serial No. 335,764, filed on April 10, 1989, which application is assigned to the same assignee as the present invention. The disclosure in such application is incorporated herein by reference.

The wicking layer(s) 34 is comprised of hydrophilic fibers, such as rayon fibers, cellulosic fibers, peat moss, acrylic fibers, or mixtures thereof. The cellulosic fibers include wood pulp fibers, cotton linters, and the like. The wood pulp fibers generally are those that are used to form the fluff or fibrous batt layer in conventional absorbent products such as disposable diapers, sanitary napkins, etc. other cellulosic fibers that might be used are rayon fibers, flax, hemp, jute, ramie, cotton and the like. The fibers or peat moss or mixtures thereof are placed in such a way as to form a layer in which the particles are close to one another so as to provide a higher capillary pressure to promote wicking of liquid in the plane of the layer. What appears to be only a small difference in capillary pressure is all that is required for one layer to attract and drain liquid from an adjacent layer.

The wicking layer(s) 34 can be preformed and placed next to the absorbing layer 30 before compression or the wicking layer particles can be air-laid, mechanically entangled therewith, or wet-laid on to the absorbing layer before compression.

A transition zone 35 is formed at the junction of the absorbing layer 30 and the wicking layer(s) 34. Some of the particles, e.g., fibers, of the wicking layer extend into and become integral with the absorbing layer. The region in which the majority of the extending particles lie is identified as the transition zone. In the transition zone, there is a composite of absorbing layer fibers, superabsorbent material, and wicking layer particles. The wicking layer particles which extend into the absorbing layer are in intimate contact with some of the superabsorbent material of the absorbing layer. This permits the liquid to commence its migration in the z direction to reach the superabsorbent material. As the liquid progresses in the z direction, the superabsorbent material becomes soft and releases the absorbing layer fibers which permit the absorbing layer to return substantially to its uncompressed thickness or more, i.e., from the thickness shown in FIG. 24 to the thickness shown in FIG. 23. As the absorbing layer returns to its uncompressed thickness, larger void areas are provided for storage of the liquid and for increased swelling of the superabsorbent material as it absorbs the liquid residing in the void areas. The absorbing layer tends to return to its uncompressed thickness or more, probably because of both the resiliency of the fibers and the swelling of the superabsorbent material.

In order for the absorbing layer fibrous web to provide the necessary medium for absorbing liquid, it is preferred that the fibrous web has an initial dry bulk of at least about 20 cc/gm, a dry bulk recovery of at least 30 percent, (preferably 50 percent) , a wet bulk of at least about 30 cc/gm, and a basis weight of less than about 4 oz/yd². The initial dry bulk is the area times thickness of the layer under a load of 0.01 pounds per square inch calculated in cubic centimeters. This value is divided by the weight in grams in order to provide the measurement in cubic centimeters per gram. The dry bulk recovery is obtained by subjecting the web to a load of 1.75 psi for five minutes, removing the load and allowing the web to rest for one minute, subjecting the web to a load of 0.01 psi for one minute and then measuring the final dry bulk while under the 0.01 psi load. The dry bulk recovery is the final bulk divided by the initial bulk expressed in percent. The wet bulk is measured in the same manner as the initial dry bulk except that the web has been saturated with water. If the fibrous web is provided with a dry bulk recovery of at least 20 percent (preferably 50 percent) , an initial dry bulk of at least 40 cc/gm. a wet bulk of at least 30 cc/gm, with a web basis weight of less than 4.0 oz/yd², the fibrous web can retain superabsorbent material up to at least 1,200 percent of the dry basis weight of the web. It is preferably that the web contain 200 percent to 1,500 percent by weight, dry basis, superabsorbent to the dry basis weight of the web and most preferred is a range from about 600 percent to about 1,000 percent.

The resulting compressed composite structure is too stiff due to the high loading of superabsorbent particles in the absorbing layer. The structure is softened to a low Taber stiffness value by subjecting it to mechanical working procedures. In accordance with a preferred embodiment such mechanical working procedures include a microcorrugating procedure and then a perf- embossing procedure substantially in the manner as disclosed in U.S. Patent No. 4,605,402, the disclosure of which patent is incorporated herein by reference. The compressed composite structure is reduced to a moisture content less than 10%, preferably less than about 6%, most preferably about 5%, and directed through microcorrugating rolls preferably in the machine direction. The microcorrugating rolls are preferably set with an interference of 0.025 to 0.03 inch in the machine direction and about 0.01 inch in the cross direction in order to break up the superabsorbent particles to a somewhat uniform size and create hinge lines resulting in a flexible, pliable, soft feel. The microcorrυgated compressed composite structure is then subjected to perf-embossing wherein the superabsorbent particle size is further reduced. During the perf- embossing procedure, the compressed composite is passed through a pair of rolls which have knuckles and which intermesh to shear the structure to produce raised areas produced by lower knuckles and depressed densified areas produced by upper knuckles. Interconnecting the raised areas and the depressed areas are intermediate portions which have received most of the mechanical working. At locations where the upper knuckles pass very close to the lower knuckles of the rolls, the work applied to the composite structure produces apertures in it. The length of the apertures can be varied by controlling the overlap of the upper knuckles and lower knuckles or the size of the knuckles of the rolls.

The various absorbent panel embodiments of the invention include a bulk layer 18. In accordance with a preferred embodiment of the invention, bulk layer 18 comprises a layer of hydrophilic fibers, most preferably a batt formed of wood pulp fibers as is well known in the art. The hydrophilic fibers may include other cellulosic fibers, rayon fibers, peat moss, acrylic fibers, polyester or polypropylene fibers treated with a surfactant, or a mixture of both. In the embodiments of the invention wherein the bulk layer 18 is not positioned between the compressed composite absorbent layer 16 and the facing layer 12, the bulk layer 18 may comprise a layer of hydrophobic fibers or a layer of foam material. The hydrophobic fibers may include polyester fibers, polypropylene fibers, polyethylene fibers or sheath core fibers made from such fibers, which fibers may be either unbonded or bonded thermally or chemically. In such embodiments of the invention, the layer 18 may be further formed of polyethylene, polyester or polypropylene melt blown fiber webs or polyethylene or polyurethane foam layers. The bulk layer 18 may be embossed in a well known manner.

A discussion of the various embodiments of the absorbent panel 14 in accordance with the invention hereinbelow follows. Each of these absorbent panels includes a bulk layer 18 and a compressed composite absorbent layer 16. In each of these embodiments the compressed composite absorbent layer 16 is located at a front portion of the panel that comprises from about 40 percent to 80 percent of the length of the absorbent panel 14, and most preferably about 70 percent of the length of the panel. The forward portion of the compressed composite absorbent layer preferably extends from the front edge of the absorbent panel 14, but may extend from a location a short distance inwardly of the front edge of the panel (as shown in phantom lines in FIG. 4A) . The width of the compressed composite absorbent layer 16 is preferably about the same as the width of the absorbent panel 14, but may be less than the width of the panel (as shown in phantom lines in FIG. 4A) . As will become more apparent, the absorbent panels 14 may be provided with a cushion web 40 that forms an intermediate layer between the nonwoven facing sheet 12 and the absorbent core, facilitating liquid flow from the facing sheet to the core. The cushion web 40 is preferably a low density, low basis weight distribution of hydrophilic staple polyester fiber laid on the surface of the compressed composite absorbent layer 16. The web is preferably not bonded by any means other than physical entanglement. The absorbent panel may further be wrapped with a tissue layer 42 of cellulosic fibers or other non-woven hydrophilic material, as is well known in the art, to prevent linting of pulp fibers upwardly through the facing layer 12 and to induce additional wicking and generate stability. The cushion web 40 and the tissue layer 42 are positioned as shown in the drawings with respect to the various embodiments.

Referring to FIGS. 4A and 4B, an absorbent panel 14 in accordance with a first preferred embodiment of the invention is shown including a compressed composite absorbent layer 16 and a bulk layer 18 of hydrophilic fibers. Layer 18 is positioned below the compressed composite layer 16 and is dimensioned so as to have substantially the same width and length dimensions as panel 14. The compressed composite absorbent layer 16 is located above a front portion of the layer 18 and extends from the front edge thereof and is substantially of the same width as layer 18. For use in a mid-size diaper (12-26 lbs.), the layer of hydrophilic fibers 18 is preferably about 14.75 inches long and 5.0 inches wide and the compressed composite layer is preferably about 10.0 inches long and 5.0 inches wide. For use in larger or smaller diapers, these dimensions are proportionately larger or smaller. The layer 18 is wrapped with a tissue layer 42 and a cushion web 40 is positioned above layer 16.

The layer of hydrophilic fibers 18 preferably made from pulp fibers and has a basis weight of from about 1.5 oz/yd² to about 6.0 oz/yd², and most preferably about 3.0 oz/yd². Layer 18 has a density of from about .07 gm/cc to about .14 gm/cc, most preferably about 0.1 gm/cc. The compressed composite absorbent layer 16 preferably has a superabsorbent coated fibrous web 30 having a basis weight from about 3.5 oz/yd² to about 40 oz/yd², and preferably about 12.0 oz/yd². Wicking layers 34 are provided above and below the fibrous web 30. In accordance with this particular embodiment the basis weight of the upper wicking layer is less than the basis weight of the lower wicking layer. The basis weight of the upper wicking layer is preferably about 1.8 oz/yd² and the basis weight of the lower wicking layer is preferably about 4.5 oz/yd². However, the basis weight of the upper and lower wicking layers may be substantially equal and preferably about 4.5 oz/yd². It has been determined that positioning layer 16 above layer 18 results in reduced surface wetness strike back.

Bulk layer 18 in the embodiment shown in FIGS. 4A and 4B, may alternately be formed from hydrophobic fibers or a foam material as discussed above. Bulk layer 18 formed from textile length hydrophobic fibers preferably has a basis weight of from 0.4 oz/yd² to about 2.0 oz/yd², most preferably about 0.8 oz/yd². Referring to FIGS. 5A and 5B, in accordance with a second preferred embodiment of the invention, an absorbent panel 14 is constructed substantially as described above with respect to the embodiment shown in FIGS. 4A and 4B, except that the tissue layer 42 is wrapped around the entire panel including the layers 16, 18 and 40.

A third preferred embodiment of the invention is shown in FIGS. 6A and 6B, wherein the absorbent panel 14 is constructed substantially as described above with respect to the embodiment shown in FIGS. 5A and 5B, except that the relative basis weights of the upper and lower wicking layers 34 are reversed.

A fourth preferred embodiment of the invention is shown in FIGS. 7A and 7B, wherein the absorbent panel 14 is constructed substantially as described above with respect to the embodiment shown in FIGS. 4A and 4B, except that the relative basis weights of the upper and lower wicking layers 34 are reversed.

Referring to FIGS. 8A and 8B, a fifth preferred embodiment of the invention is shown wherein the compressed composite layer 16 is positioned below the bulk layer 18 and the cushion web 40 is positioned above layer 18. The tissue layer 42 is wrapped around the entire panel including the layers 16, 18 and 40. The compressed composite absorbent layer 16 is formed so that the upper wicking layer 34 has a higher basis weight than the lower wicking layer 34. In this embodiment, bulk layer 18 is made from hydrophilic fibers. A sixth preferred embodiment of the invention is shown in FIGS. 9A and 9B, wherein the absorbent is constructed substantially as described above with respect to the embodiment shown in FIGS. 8A and 8B, except that the tissue layer 42 is wrapped only around the layer of hydrophilic fibers 18.

In FIGS. 10A and 10B a seventh preferred embodiment of the invention is shown wherein the absorbent panel 14 is constructed substantially as described with respect to the embodiment shown in

FIGS. 8A and 8B, except that the relative basis weights of the upper and lower wicking layers 34 are reversed.

An eighth preferred embodiment of the invention is shown in FIGS. 11A and 11B wherein the absorbent panel 14 is constructed substantially and described with respect to the embodiment shown in FIGS. 9A and 9B, except that the relative basis weights of the upper and lower wicking layers 34 are reversed.

In accordance with other preferred embodiments of the invention shown in FIGS. 12A and B, 13A and B, and 14A and B, the absorbent panels include a compressed composite absorbent layer 16 and a bulk layer 18 that are positioned adjacent one another in substantially an end to end relationship. The compressed composite absorbent layer 16 extends from about 40 percent to about 80 percent of the length of the panel, most preferably about 70 percent of the length of the panel. The bulk layer 18 may be wrapped with a tissue layer 42 and a cushion web 40 may be positioned above the layers 16 and 18. In the ninth preferred embodiment of the invention (FIGS. 12A and 12B) , the inner end portions of the layers 16 and 18 abut against one another. In the tenth preferred embodiment of the invention (FIGS. 13A and 13B) , the inner end portion of bulk layer 18 extends over an upper surface of the inner end portion of the compressed composite absorbent layer 16. In the eleventh preferred embodiment of the invention (FIGS. 14A and 14B) , the inner end portion of bulk layer 18 extends below a lower surface of the inner end portion of the compressed composite absorbent layer 16. The basis weights of the upper wicking layer 34 may be the same as, more than, or less than the basis weight of the lower wicking layer 34.

Bulk layer 18, in the embodiments shown in FIGS. 12A and B, 13A and B, and 14A and B, may alternately be formed of hydrophilic fibers, hydrophobic fibers, or a foam material as discussed hereinabove. Referring to FIGS. 15A and 15B, a twelfth preferred embodiment of the invention is shown wherein the compressed composite absorbent layer 16 comprises a plurality of spaced apart longitudinal segments. Although shown positioned above the bulk layer 18, the compressed composite absorbent segments may be positioned below the layer 18. The basis weight of the upper wicking layer 34 may be the same as, more than, or less than the basis weight of the lower wicking layer 34. When bulk layer 18 is positioned below layer 16, bulk layer 18 may comprise hydrophilic fibers, hydrophobic fibers or foam material as discussed hereinabove. This embodiment results in a corrugated arrangement that enhances fit between the legs of the infant.

As shown in FIGS. 16A and 16B, a thirteenth preferred embodiment of the invention is shown wherein the front portion of the bulk layer 18 is compressed to reduce the thickness thereof and the compressed composite absorbent layer 16 is received in the compressed portion such that the combined thickness of the layer 16 and the front portion of layer 18 is substantially the same as the thickness of the remaining or rear portion of layer 18. The layer 16 may be positioned above or below the layer 18. The basis weight of the upper wicking layer 34 may be the same as, more than, or less than the basis weight of the lower wicking layer 34. When bulk layer 18 is positioned below layer 16, bulk layer 18 may comprise hydrophilic fibers, hydrophobic fibers or foam material as discussed hereinabove.

Referring the FIGS. 17-19, a fourteenth preferred embodiment of the invention is shown wherein the width of the compressed composite absorbent layer 16. is less than the width of the bulk layer 18 defining side flap portions 44 that extend along each side edge portion of layer 16. Layer 18 is diagonally cut along lines 46 at the longitudinal side margins thereof allowing the side flaps 44 to wrap partially around layer 16 and to form wings 48 at the rear portion of the panel. A tissue layer 42 is wrapped around the layers 16 and 18. A fifteenth preferred embodiment of the invention is shown in FIGS. 20-22 of similar construction to the embodiment shown in FIGS. 17-19, except that the wings 48 are formed at the front portion of the panel. The embodiments shown in FIGS. 17-19 and 20-22 provide softer pad side margins and a liquid barrier dam created by the side flaps 44 to enhance diaper comfort and increased absorptive capacity. In these embodiments, the bulk layer 18 may comprise hydrophilic fibers, hydrophobic fibers or foam material. If the bulk layer 18 is made from either hydrophobic fibers or foam material, the exposed portion of layer 16 in facing relationships with facing sheet 12 should preferably be at least 3.0 inches wide to permit entry of fluid. In certain of the above discussed embodiments wherein a front portion of the bulk layer 18 extends above or below the compressed composite absorbent layer 16, it is anticipated that it may be desirable to provide superabsorbent material to the front portion or a central portion of the bulk layer 18 in a well known manner to enhance the absorptive capacity of the panel.

In accordance with a broad aspect of the present invention the layer 16 of the absorbent panel preferably comprises an integrated superabsorbent containing absorbent matrix, such as the above-described compressed composite absorbent layer, or such as disclosed in common-assigned, copending U.S. Application Serial No. 07/326,199, filed March 20, 1989. The absorbent matrix of the compressed composite absorbent layer, as well as that disclosed in the above-identified application, each comprises superabsorbent particles bonded to a heat-bonded integrating structure, to thereby provide the matrix in a structurally stable, unified form. In the compressed composite absorbent layer, the integrating structure comprises a resilient heat-bonded fibrous web to which particles of superabsorbent material are bonded, preferably attendant to in situ formation, while the matrix of the above application includes an integrating structure in the form of a heat-bonded binder composition to which the superabsorbent particles are bonded.

Each type of matrix also includes hydrophilic fibrous material positioned in liquid-transferring relation with at least some of the superabsorbent particles. To this end, the compressed composite absorbent structure includes a substantially continuous hydrophilic fibrous layer coextensive with the resilient fibrous web thereof. By comparison, the structure of the above application includes hydrophilic fibrous material to which the heat-bonded binder composition is applied, whereby the fibrous material is heat-bonded, with the superabsorbent particles bonded to the fibrous material by the binder composition.

The absorbent panel structures in accordance with the invention are light in weight, of less bulk and thickness and less expensive to manufacture, and still substantially maintain performance characteristics of the heavier, bulkier and more expensive prior art absorbent panel structures. Tests have determined that about 80% of the absorption of body fluids is in the front 60% of the absorbent panel maximizing use of the superabsorbent material contained in the compressed composite absorbent layer.

From the foregoing it will be observed that numerous variations and modifications may be effected without departing from the true spirit and scope of the novel concepts of this invention.

Claims

What Is Claimed 1st

1. A disposable diaper including an absorbent panel positioned between a substantially liquid impervious backing sheet and a relatively liquid pervious facing sheet, said absorbent panel comprising: a bulk layer; and a compressed composite absorbent layer having a resilient fibrous web containing at least about 200 percent superabsorbent material by weight of said fibrous web distributed therein and a wicking layer of densified hydrophilic fibers, said fibrous web being maintained in a compressed state by said superabsorbent material such that upon wetting of said superabsorbent material said fibrous web expands from its compressed state due to the inherent resilience of said fibrous web to facilitate swelling of said superabsorbent material, said wicking layer being coextensive with at least a portion of a respective surface of said fibrous web to promote liquid transport within said absorbent layer, wherein said compressed composite absorbent layer is located at a front portion of said panel that comprises from about 40 percent to about 80 percent of the length of said panel.

2. The disposable diaper as defined in claim 1 wherein said compressed composite absorbent layer is superimposed above said front portion of said bulk layer.

3. The disposable diaper as defined in claim 2 wherein a front edge of said compressed composite absorbent layer is located generally above a front edge of said bulk layer.

4. The disposable diaper as defined in claim 3 wherein a tissue layer is wrapped around at least a portion of said bulk layer.

5. The disposable diaper as defined in claim 3 wherein a cushion web layer is positioned between said compressed composite absorbent layer and said facing sheet.

6. The disposable diaper as defined in claim 5 wherein a tissue layer is wrapped around at least a portion of said absorbent panel and said cushion web layer.

7. The disposable diaper as defined in claim 2 wherein said compressed composite absorbent layer includes a wicking layer located above and below said fibrous web.

8. The disposable diaper as defined in claim 7 wherein the basis weight of each of said wicking layers is substantially the same.

9. The disposable diaper as defined in claim 7 wherein the basis weight of the wicking layer above said fibrous web is greater than the basis weight of the wicking layer below said fibrous web.

10. The disposable diaper as defined in claim 7 wherein the basis weight of the wicking layer above said fibrous web is less than the basis weight of the wicking layer below said fibrous web.

ll. The disposable diaper as defined in claim 1 wherein said compressed composite absorbent layer is located below said front portion of said bulk layer.

12. The disposable diaper as defined in claim 11 wherein a front edge of said compressed composite absorbent layer is located generally above a front edge of said bulk layer.

13. The disposable diaper as defined in claim 12 wherein a tissue layer is wrapped around at least a portion of said bulk layer.

14. The disposable diaper as defined in claim 12 wherein a cushion web layer is positioned between said compressed composite absorbent layer and said facing sheet.

15. The disposable diaper as defined in claim 14 wherein a tissue layer is wrapped around at least a portion of said absorbent panel and said cushion web layer.

16. The disposable diaper as defined in claim 11 wherein said compressed composite absorbent layer includes a wicking layer located above and below said fibrous web.

17. The disposable diaper as defined in claim 16 wherein the basis weight of each of said wicking layers is substantially the same.

18. The disposable diaper as defined in claim 16 wherein the basis weight of the wicking layer above said fibrous web is greater than the basis weight of the wicking layer below said fibrous web.

19. The disposable diaper as defined in claim 16 wherein the basis weight of the wicking layer above said fibrous web is less than the basis weight of the wicking layer below said fibrous web.

20. The disposable diaper as defined in claim 1 wherein said compressed composite absorbent layer and said bulk layer are positioned adjacent one another in substantially an end to end relationship.

21. The disposable diaper as defined in claim 20 wherein a tissue layer is wrapped around at least a portion of said bulk layer.

22. The disposable diaper as defined in claim 20 wherein a cushion web layer is positioned between said absorbent panel and said facing sheet.

23. The disposable diaper as defined in claim 20 wherein an inner end portion of said bulk layer overlaps an inner end portion of said compressed composite absorbent layer.

24. The disposable diaper as defined in claim 23 wherein said inner end portion of said bulk layer extends over an upper surface of said inner end portion of said compressed composite absorbent layer.

25. The disposable diaper as defined in claim 23 wherein said inner end portion of said bulk layer extends below a lower surface of said inner end portion of said compressed composite absorbent layer.

26. The disposable diaper as defined in claim 2 wherein said compressed composite absorbent layer comprises a plurality of spaced apart longitudinal segments.

27. The disposable diaper as defined in claim 26 wherein said compressed composite absorbent layer is positioned above said bulk layer.

28. The disposable diaper as defined in claim 26 wherein said compressed composite absorbent layer is positioned below said bulk layer.

29. The disposable diaper as defined in claim 26 wherein a tissue layer is wrapped around at least a portion of said bulk layer.

30. The disposable diaper as defined in claim 26 wherein a cushion web layer is positioned between said compressed composite absorbent layer and said facing sheet.

31. The absorbent panel structure as defined in claim 2 wherein said front portion of said bulk layer is compressed to reduce the thickness thereof such that the combined thickness of said compressed composite absorbent layer and said portion of said bulk layer is substantially the same as the thickness of the remaining portion of said bulk layer.

32. The disposable diaper as defined in claim 11 wherein said front portion of said bulk layer is compressed to reduce the thickness thereof such that the combined thickness of said compressed composite absorbent layer and said portion of said bulk layer is substantially the same as the thickness of the remaining portion of said bulk layer.

33. The disposable diaper as defined in claim 2 wherein the width of said bulk layer is greater than the width of said compressed composite absorbent layer defining a longitudinal flap portion that extends along each side edge portion of said compressed composite absorbent layer and said flap portions are folded over into covering relationship with a portion of said compressed composite absorbent layer.

34. The disposable diaper as defined in claim

33 wherein a rear section of said bulk layer extends transversely beyond said folded flap portions so as to define wing portions.

35. The disposable diaper as defined in claim

2 wherein the width of said bulk layer is greater than the width of said compressed composite absorbent layer defining a longitudinal flap portion that extends along a rear section and a middle section of said bulk layer and said flap portions are folded over into covering relationship with a portion of said rear section of said bulk layer and a rear and middle section of said compressed composite layer.

36. The disposable diaper as defined in claim

35 wherein a front section of said bulk layer extends transversely beyond said folded flap portions so as to define wing portions.

37. The disposable diaper as defined in claim

2 wherein a front edge portion of said bulk layer extends a short distance beyond a front edge portion of said compressed composite absorbent layer.

38. The disposable diaper as defined in claim 2 wherein side edge portions of said bulk layer extend a short distance beyond side edge portions of said compressed composite absorbent layer.

39. The disposable diaper as defined in claim 2 wherein a front edge portion of said compressed composite absorbent layer extends a short distance beyond a front edge portion of said bulk layer.

40. The disposable diaper as defined in claim 2 wherein side edge portions of said compressed composite absorbent layer extend a short distance beyond side edge portions of said bulk layer.

41. The disposable diaper as defined in claim 11 wherein a front edge portion of said bulk layer extends a short distance beyond a front edge portion of said compressed composite absorbent layer.

42. The disposable diaper as defined in claim 11 wherein side edge portions of said bulk layer extend a short distance beyond side edge portions of said compressed composite absorbent layer.

43. The disposable diaper as defined in claim 11 wherein a front edge portion of said compressed composite absorbent layer extends a short distance beyond a front edge portion of said bulk layer.

44. The disposable diaper as defined in claim 11 wherein side edge portions of said compressed composite absorbent layer extend a short distance beyond side edge portions of said bulk layer.

45. The disposable diaper as defined in claim 1 wherein said bulk layer includes hydrophilic fibers.

46. The disposable diaper as defined in claim 1 wherein said bulk layer includes hydrophobic fibers.

47. The disposable diaper as defined in claim 1 wherein said bulk layer includes a foam material.

48. The disposable diaper as defined in claim

1 wherein said bulk layer comprises a batt of wood pulp fibers having a basis weight from about 1.5 oz/yd² to about 6.0 oz/yd².

49. The disposable diaper as defined in claim

48 wherein said batt of wood pulp fibers has a density from about .07 gm/cc to about .14 gm/cc.

50. The disposable diaper as defined in claim 46 wherein said bulk layer has a basis weight from about

0.4 oz/yd² to about 2.0 oz/yd².

51. A disposable diaper including an absorbent panel positioned between a substantially liquid impervious backing sheet and a relatively liquid pervious facing sheet, said absorbent panel comprising: a superabsorbent containing absorbent matrix having enhanced structural integrity and comprising a plurality of superabsorbent particles, and means for integrating said superabsorbent particles to provide said matrix in a structurally stable, unified form, said integrating means including heat bond means for structural integrity, with said superabsorbent particles being bonded to said integrating means, said matrix further comprising hydrophilic fibrous material

positioned in liquid-transferring relation with at least some of said superabsorbent particles for promoting liquid transport within said absorbent matrix to said superabsorbent particles; and a bulk layer positioned in liquid transferring relation with said absorbent matrix, said absorbent matrix being located at a front portion of said panel assembly that comprises from about 40 percent to about 80 percent of the length of said panel assembly.

52. The disposable diaper as defined in claim 51 wherein said integrating means comprises a heat- bonded resilient fibrous web to which said superabsorbent particles are bonded, said hydrophilic fibrous material being provided as a substantially continuous layer generally coextensive with said fibrous web.

53. The disposable diaper as defined in claim 51 wherein said superabsorbent particles comprise at least about 200 percent by weight of said fibrous web.

54. The disposable diaper as defined in claim

53 wherein said fibrous web being maintained in a compressed state by said superabsorbent material such that upon wetting of said superabsorbent material said fibrous web expands from its compressed state due to the inherent resilience of said fibrous web to facilitate swelling of said superabsorbent material.