WO2001097736A1

WO2001097736A1 - Absorbent article having improved resiliency at body contacting surface

Info

Publication number: WO2001097736A1
Application number: PCT/US2000/017021
Authority: WO
Inventors: Brian Francis Gray; Yuka Momotani
Original assignee: The Procter & Gamble Company
Priority date: 2000-06-20
Filing date: 2000-06-20
Publication date: 2001-12-27
Also published as: AU2000254983A1

Abstract

The present invention is directed to an absorbent article having a body contacting surface. In one aspect of the invention, at least a portion of the body contacting surface has a resilient force which is less than about 20 gf at 3 mm in depth, about 40 gf at 5 mm in depth, or about 100 gf at 10 mm in depth. The invention answers the need for an absorbent article that can provide improved performance for preventing a leakage of body discharges by improved compressibility and resiliency. The invention also answers the need for an absorbent article that can provide an improved comfortable feel at the perineum or urogenital area while keeping a better fit to wearer's body by similar means.

Description

ABSORBENT ARTICLE HAVING IMPROVED RESILIENCY AT BODY CONTACTING SURFACE

FIELD OF THE INVENTION

The present invention relates to absorbent articles such as sanitary napkins, panty liners, interlabial absorbent articles, tampons, diapers, training pants, incontinence articles, and the like. More particularly, the present invention relates to absorbent articles which have an improved resiliency at the body contacting surface.

BACKGROUND Absorbent articles such as sanitary napkins, pantiliners, and incontinence articles are devices that are typically worn in the crotch region of an undergarment. These devices are designed to absorb and retain liquid and other discharges from the human body and to prevent body and clothing soiling.

For example, sanitary napkins are a type of absorbent article worn by women in a pair of panties that is normally positioned between the wearer's legs, adjacent to the perineum area. A wide variety of shapes and dimensions of sanitary napkins is currently used by women for the collection of menses and other bodily discharges.

It is desirable that absorbent articles or sanitary napkins maintain contact with and conform as closely as possible to the wearer's body. Such a body-conforming capability increases the effectiveness of the absorbent article by reducing the possibility that body discharges (e.g., menses) will travel around the perimeter of the absorbent article and leak. There have been a number of recent efforts to provide sanitary napkins and other absorbent articles with improved body-conforming characteristics. For example, U.S. Patent 4,950,264 issued to Osborn on August 21 , 1990, is directed to a thin, flexible sanitary napkin that is capable of handling medium to high menstrual flows. The sanitary napkin in the Osborn patent is described as being highly flexible and conforming very well to the various shapes of the female urogenital region.

In addition, International Publication No. WO 94/16658, entitled "Generally Thin, Flexible Sanitary Napkin With Central Absorbent Hump", published in the name of Osborn on August 4, I994, discloses a generally thin, flexible sanitary napkin which has a central absorbent hump, and is capable of handling medium to high menstrual flows. The hump is particularly useful in fitting into the space between the wearer's labia to more readily intercept menses and other bodily discharges when they leave the wearer's body. However, the body contacting surface of conventional absorbent articles such as sanitary napkins is generally harder and/or less compressible and/or less resilient than the skin/flesh of a wearer's perineum or urogenital area (e.g., an external vulva area). This tends to limit the intimate fit of absorbent articles to the wearer's body thereby allowing leakage of body discharges. More specifically, less compressible absorbent articles are limited in their ability to closely conform to the body while the wearer is at rest or during movement causing local gaps or channels for body discharges to escape resulting in leakage. Less resilient absorbent articles are limited in their ability to return to their original shape quickly when pressure is released and are thus vulnerable to leakage particularly during movement (when pressures on the absorbent article are applied and released). In addition, less compressible products also tends to contribute to wearing discomfort. During wear, harder/less compressible absorbent articles are less able to move with the body. They tend to cause pressure points, displacing the flesh locally which can lead to discomfort and negative wearing awareness. Thus, there is a need for an absorbent article that can provide improved performance for preventing a leakage of body discharges by improved compressibility and resiliency. There is also a need for an absorbent article that can provide an improved comfortable feel at the perineum or urogenital area while keeping a better fit to wearer's body by similar means.

SUMMARY The present invention is directed to an absorbent article having a body contacting surface. In one aspect of the invention, at least a portion of the body contacting surface has a resilient force which is less than about 20 gf at 3 mm in depth, about 40 gf at 5 mm in depth, or about 100 gf at 10 mm in depth.

In another aspect of the invention, the absorbent article comprises: a topsheet having a body contacting surface and an opening; a backsheet having a garment facing surface; and an absorbent body disposed between the topsheet and the backsheet. The absorbent body having a portion exposed through the opening and above the body contacting surface of the topsheet. The exposed portion of the absorbent body has a resilient force at 5 mm in depth of less than about 150 gf. The foregoing answers the need for an absorbent article that can provide improved performance for preventing a leakage of body discharges by improved compressibility and resiliency. The foregoing also answers the need for an absorbent article that can provide an improved comfortable feel at the perineum or urogenital area while keeping a better fit to wearer's body by similar means.

These and other features, aspects, and advantages of the present invention will become evident to those skilled in the art from reading of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS While the specification concludes with claims particularly pointing out and distinctly claiming the subject matter which is regarded as forming the present invention, it is believed that the invention will be better understood from the following description which is taken in conjunction with the accompanying drawings in which: Fig. 1 is a top plan view of a sanitary napkin which is one preferred embodiment of an absorbent article of the present invention;

Fig. 2 is a cross-sectional view of the sanitary napkin shown in Fig. 1 , taken along the line 2-2;

Fig. 3 is a cross-sectional view of another embodiment of the absorbent article; Fig. 4 is a cross-sectional view of yet another embodiment of the absorbent article;

Fig. 5 is a graph showing one example of the resilience property at the body contacting surface of an absorbent article; and

Fig. 6 is a transverse cross-sectional view of a human female wearer wearing an absorbent article of one preferred embodiment.

DETAILED DESCRIPTION All cited references are incorporated herein by reference in their entireties. Citation of any reference is not an admission regarding any determination as to its availability as prior art to the claimed invention.

Herein, "comprise" and "include" mean that other elements and/or other steps which do not affect the end result can be added. Each of these terms encompasses the terms "consisting of and "consisting essentially of.

Herein, "absorbent article refers to articles which absorb and contain body exudates, such as body fluid. More specifically, the term refers to articles which are placed against or in proximity to the body of the wearer to absorb and contain the various exudates discharged from the body. Herein, "absorbent article" is intended to include sanitary napkins, pantiliners, diapers, and incontinence pads (and other articles worn in the crotch region of a garment).

Herein, "disposable" refers to articles which are intended to be discarded after a single use and preferably recycled, composted, or otherwise disposed of in an environmentally compatible manner. (That is, they are not intended to be laundered or otherwise restored or reused as an absorbent article.) In the preferred embodiments illustrated in Figs. 1-5, the absorbent article is a menstrual pad designated 20 that is designed to replace conventional sanitary napkins. Herein, "sanitary napkin refers to an article which is worn by females adjacent to the pudendal region that is intended to absorb and contain the various exudates which are discharged from the body (e.g., blood, menses, and urine). Although the present invention is shown in the drawings as a menstrual pad that is intended to replace conventional sanitary napkins, it should be understood that the present invention is not limited to the particular types or configurations of absorbent articles shown in the drawings.

Herein, "body contacting surface" means that surface of the article which contacts to the body of the wearer, while the term "garment contacting surface" is the opposite surface of the article that faces away from the wearer and contacts to the wearer's undergarments when the disposable absorbent article is worn.

Herein, "body side surface" means that surface of the article or component which is intended to be worn toward or adjacent to the body of the wearer, while the term "garment side surface" is on the opposite side that faces away from the wearer and is oriented toward the wearer's undergarments when the disposable absorbent article is worn. Disposable absorbent articles and components thereof, including the topsheet, backsheet, absorbent body, and any individual layers of their components, have a body side surface and a garment side surface.

The absorbent article of the present invention has a body contacting surface. In a preferred embodiment of the present invention, the absorbent article includes a liquid impervious backsheet, and an absorbent body which is associated with the backsheet. The absorbent body has the body contacting surface. The backsheet has a garment contacting surface. The absorbent body and the backsheet is associated in such a manner that the absorbent body is situated between the backsheet and the fluid discharge region of the wearer of the absorbent article. The absorbent body and the backsheet may be associated in a variety of configurations known in the art. In the absorbent article of the present invention, at least a portion of the body contacting surface has a resilient force which is less than about 20 gf at 3 mm in depth, about 40 gf at 5 mm in depth, or about 100 gf at 10 mm in depth. The method for measuring the resilient force at an applied depth is explained in detail in the Test Method Section. When the absorbent article is applied on the wearer's body, this portion is compressible and resilient enough to conform closely to the wearer's perineum or urogenital area thereby improving intimate contact between the wearer's skin and the body contacting surface of the absorbent article. Further, it allows the absorbent article to conform better to the body as the position of the absorbent article changes by the wearer's movement. Through these functions, the present invention provides less opportunity for body discharges to escape leading to leakage, and provides improved wearing comfort.

In a more preferred embodiment, at least a portion of the body contacting surface has a resilient force which is less than about 15 gf at 3 mm in depth, about 30 gf at 5 mm in depth, or about 60 gf at 10 mm in depth. More preferably, at least a portion of the body contacting surface has a resilient force which is less than about 7 gf at 3 mm in depth, about 10 gf at 5 mm in depth, or about 30 gf at 10 mm in depth.

In one preferred embodiment, at least a portion of the body contacting surface has a resilient force which is less than about 20 gf at 3 mm in depth, about 40 gf at 5 mm in depth, and about 100 gf at 10 mm in depth. With this resilience at the body contacting surface, the absorbent article can suitably provide the above described benefit for wide range of wearers who may have a different skin property (i.e., a skin resilience) at the perineum or urogenital area. In a more preferred embodiment, at least a portion of the body contacting surface has a resilient force which is less than about 15 gf at 3 mm in depth, about 30 gf at 5 mm in depth, and about 60 gf at 10 mm in depth. More preferably, at least a portion of the body contacting surface has a resilient force which is less than about 7 gf at 3 mm in depth, about 10 gf at 5 mm in depth, and about 30 gf at 10 mm in depth.

In an yet more preferred embodiment, at least a portion of the body contacting surface has a resilient hysteresis in a compressive depth range between about 0 mm and about 5 mm, of less than about 30 gf-mm, preferably about 20 gf-mm, and more preferably about 10 gf-mm. The method for measuring the resilient hysteresis is explained in detail in the Test Method Section. In a preferred embodiment, at least a portion of the body contacting surface has a hump which touches the wearer's perineum or urogenital area (e.g., the labia minora) when the absorbent article is applied on the wearer's body. The configuration and size of the hump are varied depending upon the design of the absorbent article so that the absorbent article can provide an improved contact of the body contacting surface to the perineum or urogenital area.

In general, the absorbent body is capable of receiving, absorbing or retaining liquids (e.g., menses, urine, and/or other body exudates). The absorbent body is preferably compressible, conformable, and non-irritating to the wearer's skin. The absorbent body may be manufactured in a wide variety of sizes and shapes (e.g., rectangular, oval, hourglass, "T" shaped, dog bone, asymmetric, etc.). The absorbent body can be formed by a single layer material or a plurality of layered materials as long as it meets the resilience property described above. The absorbent body may include any of a wide variety of liquid-absorbent materials commonly used in absorbent articles, such as comminuted wood pulp, which is generally referred to as airfelt. Examples of other suitable absorbent materials for use in the absorbent body include creped cellulose wadding; meltblown polymers including coform; chemically stiffened, modified or cross-linked cellulosic fibers; synthetic fibers such as crimped polyester fibers; peat moss; tissue including tissue wraps and tissue laminates; absorbent foams; absorbent sponges; super-absorbent polymers; absorbent gelling materials; or any equivalent material or combinations of materials, or mixtures of these.

In a preferred embodiment, the absorbent body includes (or is formed by) a polymeric foam material. Preferred polymeric foam materials are disclosed, for example, U.S. Patent No. 5,899,893 issued to Dyer et al. on May 4, 1999.

In an alternative preferred embodiment, the absorbent body include (or is formed by) a fibrous material. Such a fibrous material includes synthetic or natural component fibers having a low density, and/or a combination thereof. Preferably, these component fibers would be loosely bonded and/or entangled one another to create a structure that retains the integrity of the fibrous material. Preferably, the component fibers have from about 0.5 denier to about 20 denier, more preferably from about 1 denier to about 10 denier, and have a dry density of from about 0.002 g/cm³ to about 0.06 g/cm³, and more preferably from about 0.004 g/cm³ to about 0.04 g/cm³. In one preferred embodiment, the component fibers are air laid fibers including about 10% of cellulose fibers and about 90% of bi-component fibers having a polyethylene in the sheath and a polypropylene in the core.

In an alternative preferred embodiment, the component fibers are chemically stiffened fibers. Herein, "chemically stiffened fibers" means any fibers which have been stiffened by chemical means to increase stiffness of the fibers under both dry and wet conditions. Such means include the addition of chemical stiffening agents which, for example, coat and/impregnate the fibers. Such means also include the stiffening of the fibers by altering the chemical structure of the fibers themselves, e.g., by cross-linking polymer chains. In one preferred embodiment, the component fibers are cellulosic fibers which are coated or impregnated with a chemical stiffening agent. Preferred agents for such a chemical stiffening agent include polycarboxylates such as a citric acid. The polycarboxylate stiffening agents and a process for making stiffened fibers from them are described in U.S. Patent 5,190,563, issued to Herron et al. on March 2, 1993.

In an yet alternative preferred embodiment, the component fibers are loose fibers which form a mat of such fibers. Herein, "loose fibers" means any fibers which are not boded one another but entangled one another to form the mat. A referred loose fiber is a bi-component fiber having a polyethylene in the sheath and a polypropylene in the core.

The configuration and construction of the absorbent body may also be varied (e.g., the absorbent body may have varying caliper zones and/or have a profile so as to be thicker in the center; hydrophilic gradients; gradients of the absorbent composite, super-absorbent gradients; or lower average density and lower average basis weight zones, e.g., acquisition zones; or may comprise one or more layers or structures). The total absorbent capacity of the absorbent body should, however, be compatible with the design loading and the intended use of the absorbent article. Further, the size and absorbent capacity of the absorbent body may be varied to accommodate different uses such as diapers, incontinence pads, pantiliners, regular sanitary napkins, and overnight sanitary napkins, and to accommodate wearers ranging from infants to adults.

The absorbent body can include other absorbent components that are often used in absorbent articles, for example, a dusting layer, a wicking or acquisition layer, or a secondary topsheet for increasing the wearer's comfort. In a preferred embodiment, the absorbent body includes two layers, e.g., an upper layer and a lower layer. Herein, "a upper layer" is a layer that is relatively closer to the body of the wearer, while "a lower layer" is a layer that is relatively further away from the body of the wearer. Preferably, the upper layer works as an acquisition layer, while the lower layer works as a liquid storage layer. In an alternative preferred embodiment, the upper layer works as a liquid storage layer, while the lower layer works as an acquisition layer. Such an embodiment will be described by referring to Fig. 4 hereinafter.

The acquisition layer serves to quickly collect discharged body fluids, to quickly transport the fluid from the point of initial contact to other parts of the acquisition layer, and to temporarily hold such discharged body fluids until they can be absorbed by the storage layer. The distribution function of the acquisition layer is of particular importance in order to more fully utilize the capacity of the storage layer. Thus, while the acquisition layer may comprise a wide variety of absorbent materials, it preferably comprises fiber material that can rapidly transport fluid and not collapse upon being wetted so that the acquisition layer can effectively acquire and distribute second and successive fluid.

The acquisition layer can be made from any materials known in the art as long as the body contacting surface of the absorbent article meets the resilience property described above. The acquisition layer may, for example, be comprised of woven or nonwoven materials. The fibers or other components of these materials may be synthetic, or partially synthetic and partially natural. Suitable synthetic fibers include polyester, polypropylene, polyethylene, nylon, viscous rayon, or cellulose acetate fibers. Suitable natural fibers include cotton, cellulose, or other natural fibers. The acquisition layer may also be at least partially comprised of cross-linked cellulose fibers. The acquisition layer, if nonwoven, can be made by a number of different processes. These include, but are not limited to: air laid, wet laid, meltblown, spunbonded, carded, thermally bonded, air-through bonded, powder bonded, latex bonded, solvent bonded, spunlaced, and combinations of the foregoing.

The liquid storage layer can be formed by a wide variety of liquid-absorbent materials commonly used in absorbent articles, such as comminuted wood pulp; creped cellulose wadding; meltblown polymers including coform; chemically stiffened, modified or cross-linked cellulosic fibers; synthetic fibers such as crimped polyester fibers; peat moss; tissue including tissue wraps and tissue laminates; absorbent foams; absorbent sponges; superabsorbent polymers; absorbent gelling materials; or any equivalent material or combinations of materials, or mixtures of these. The backsheet is impervious to liquids (e.g., menses and/or urine) and is preferably manufactured from a thin plastic film, although other flexible liquid impervious materials may also be used. Herein, "flexible" refers to materials which are compliant and will readily conform to the general shape and contours of the human body. The backsheet prevents the exudates absorbed and contained in the absorbent body from wetting articles which contact the absorbent article such as bedsheets, pants, pajamas and undergarments. The backsheet may thus include a woven or nonwoven material, polymeric films such as thermoplastic films of polyethylene or polypropylene, or composite materials such as a film-coated nonwoven material. A suitable backsheet is a polyethylene film having a thickness of from about 0.012 mm (0.5 mil) to about 0.051 mm (2.0 mils). Exemplary polyethylene films are manufactured by Clopay Corporation of Cincinnati, Ohio, under the designation P18-1401 and by Tredegar Film Products of Terre Haute, Indiana, under the designation XP-39385. The backsheet may be embossed and/or matte finished to provide a more clothlike appearance. Further, the backsheet may permit vapors to escape from the absorbent body (i.e., the backsheet is breathable) while still preventing exudates from passing through the backsheet. The size of the backsheet is dictated by the size of the absorbent body and the exact absorbent article design selected. Preferably, the absorbent article further includes a liquid pervious topsheet which forms at least a portion of the body contacting surface of the absorbent article wherein the absorbent body is disposed between the backsheet and the topsheet.

The topsheet is preferably compliant, soft feeling, and non-irritating to the wearer's skin. Further, the topsheet is liquid pervious, permitting liquids (e.g., menses and/or urine) to readily penetrate through its thickness. A suitable topsheet may be manufactured from a wide range of materials such as woven and nonwoven materials (e.g., a nonwoven web of fibers); polymeric materials such as apertured formed thermoplastic films, apertured plastic films, and hydroformed thermoplastic films; porous foams; reticulated foams; reticulated thermoplastic films; and thermoplastic scrims. Suitable woven and nonwoven materials can be comprised of natural fibers (e.g., wood or cotton fibers), synthetic fibers (e.g., polymeric fibers such as polyester, polypropylene, or polyethylene fibers) or from a combination of natural and synthetic fibers. When the topsheet includes a nonwoven web, the web may be manufactured by a wide number of known techniques. For example, the web may be spunbonded, carded, wet-laid, melt-blown, hydroentangled, combinations of the above, or the like. The backsheet and the topsheet are positioned adjacent the garment contacting surface and the body contacting surface, respectively, of the absorbent body. The absorbent body is preferably joined with the topsheet, the backsheet, or both in any manner as is known by attachment means such as those well known in the art. However, embodiments of the present invention are envisioned wherein portions of the entire absorbent body are unattached to either the topsheet, the backsheet, or both.

For example, the topsheet and/or backsheet can be joined to the absorbent body or to each other in any suitable manner known in the art. Herein, "joined" encompasses configurations in which an element is directly secured to another element by affixing the element directly to the other element; configurations in which the element is indirectly secured to the other element by affixing the element to intermediate member(s) which in turn are affixed to the other element; and configurations in which one element is integral with another element, i.e., one element is essentially part of the other element. The backsheet and/or the topsheet may be joined to the absorbent body or to each other by a uniform continuous layer of adhesive, a patterned layer of adhesive, or an array of separate lines, spirals, or spots of adhesive. Adhesives which have been found to be satisfactory are manufactured by H. B. Fuller Company of St. Paul, Minnesota under the designation HL-1258 or H-2031. The attachment means will preferably include an open pattern network of filaments of adhesive as is disclosed in U.S. Patent 4,573,986, issued to Minetola, et al. on March 4, 1986. An exemplary attachment means of an open pattern network of filaments includes several lines of adhesive filaments swirled into a spiral pattern such as illustrated by the apparatus and method shown in U.S. Patent 3,911 ,173 issued to Sprague, Jr. on October 7, 1975; U.S. Patent 4,785,996 issued to Zwieker, et al. on November 22, 1978; and U.S. Patent 4,842,666 issued to Werenicz on June 27, 1989. Alternatively, the attachment means may include heat bonds, pressure bonds, ultrasonic bonds, dynamic mechanical bonds, or any other suitable attachment means or combinations of these attachment means as are known in the art.

In a preferred embodiment, the topsheet covers all of the body side surface of the absorbent body. Preferably, the body contacting surface formed by the topsheet forms a hump which is disposed around the area of the topsheet which touches the wearer's perineum or urogenital area when the absorbent article is applied on the wearer's body. In an alternative preferred embodiment, the topsheet has an opening around the area that touches the wearer's perineum or urogenital area (e.g., a labia minora) when the absorbent article is applied on the wearer's body. In this embodiment, at least a part of the absorbent body is exposed to the skin of the wearer through the opening so that it may touch the wearer's perineum or urogenital area (e.g., the labia minora) when the absorbent article is applied on the wearer's body. In a preferred embodiment, the exposed portion of the absorbent body has a resilient force at 5 mm in depth of less than about 150 gf, preferably about 100 gf, more preferably about 30 gf, and yet more preferably about 10 gf. The configuration and size of the opening can be varied depending upon the design of the absorbent article. In this embodiment, the rest of the body side surface of the absorbent body is covered with the topsheet. Preferably, a portion of the absorbent body projects above the body contacting surface of the topsheet through the opening to touch the wearer's perineum or urogenital area (e.g., the labia minora). The projected portion forms a hump which is a part of the body contacting surface of the absorbent article together with the topsheet.

The liquid pervious topsheets can include any material such as polyester, polyolefin, rayon and the like which is substantially porous and permits body fluid to readily pass through and into the underlying absorbent body. Fig. 1 is a top plan view of a sanitary napkin which is one preferred embodiment of an absorbent article of the present invention. Referring to Fig. 1 , the sanitary napkin 20 has two surfaces, a body contacting surface 22 and a garment contacting surface 24. The sanitary napkin 20 is shown in Fig. 1 as viewed from the body contacting surface 22. The sanitary napkin 20 has two centerlines, a principal longitudinal centerline L and a principal transverse centerline T. Herein, "longitudinal" refers to a line, axis or direction in the plane of the sanitary napkin 20 that is generally aligned with (e.g., approximately parallel to) a vertical plane which bisects a standing wearer into left and right body halves when the sanitary napkin 20 is worn. Herein, "transverse" or "lateral", are interchangeable, and refer to a line, axis or direction which lies within the plane of the sanitary napkin 20 that is generally perpendicular to the longitudinal direction.

The sanitary napkin 20 has two spaced apart longitudinal edges 26, two spaced apart transverse or end edges (or "ends") 28, which together form the periphery 30 of the sanitary napkin 20. The sanitary napkin 20 also has two end regions, which are designated first end region 32 and second end region 34. A central region 36 is disposed between the end regions 32 and 34. The end regions 32 and 34 extend outwardly in the longitudinal direction from the edges of the central region 36 about 1/8 to about 1/3 of the length of the main body portion. A detailed description of the characteristics of a central region and two end regions for a sanitary napkin is contained in U.S. Patent 4,690,680 issued to Higgins on September 1 , 1987.

The sanitary napkin 20 can have any thickness, including relatively thick, intermediate thickness, relatively thin, or even very thin (or "ultra thin"). An "ultra- thin" sanitary napkin 20 as described in U.S. Patents 4,950,264 and 5,009,653 issued to Osborn preferably has a caliper of less than about 3 mm. The embodiment of the sanitary napkin 20 shown in the drawings is intended to be an example of an ultra-thin sanitary napkin. The sanitary napkin 20 may also be relatively flexible, so that it is comfortable for the wearer. It should, however, be understood that the sanitary napkin 20 shown is merely one embodiment, and that the present invention is not limited to absorbent articles of the type or having the specific configurations shown in the drawings.

In a preferred embodiment, the body contacting surface of the sanitary napkin 20 has a hump 10 as shown in Fig. 1. Preferably, the hump 10 has a length L of from about 20 mm to about the length of the absorbent body, a width W of from about 5 mm to about 50 mm, and a height H of from about 2 mm to about 30 mm. The height H is the perpendicular distance from the body contacting surface of the topsheet to the point of the maximum amplitude on the top of the hump (as shown in Fig. 2). Preferably, the hump 10 has a length L of from about 40 mm to about 150 mm, a width W of from about 10 mm to about 45 mm, and a height H of from about 5 mm to about 15.

Fig. 2 is a cross-sectional view of the sanitary napkin 20 shown in Fig. 1 , taken along the line 2-2. The sanitary napkin 20 includes three primary components. These include a liquid pervious topsheet 38, a liquid impervious backsheet 40, and an absorbent body 42 positioned between the topsheet 38 and the backsheet 40. In this embodiment, the body contacting surface of the sanitary napkin 20 has at least a portion which forms the hump 10. In this embodiment, the hump 10 is formed by a part of the topsheet 38 and a part of the absorbent body 42 as shown in Fig. 2.

Fig. 3 is a cross-sectional view of a sanitary napkin 120 which is another embodiment of the invention. (This drawing shows an equivalent cross-sectional view to the one shown in Fig. 2.) This sanitary napkin 120 also includes a liquid pervious topsheet 138, a liquid impervious backsheet 40, and an absorbent body 142 positioned between the topsheet 138 and the backsheet 40. The topsheet 138 has an opening 100 through which a portion of the absorbent body 142 is exposed. The exposed portion is preferably above the body contacting surface 22 of the topsheet 138 thereby forming a hump 110. The hump 110 forms a part of the body contacting surface 22 of the sanitary napkin 120.

Fig. 4 is a cross-sectional view of a sanitary napkin 220 which is yet another embodiment of the invention. (This drawing shows an equivalent cross-sectional view to the one shown in Fig. 2.) This sanitary napkin 220 also includes a liquid pervious topsheet 238, a liquid impervious backsheet 40, and an absorbent body 242 positioned between the topsheet 238 and the backsheet 40. In this embodiment, the absorbent body 242 includes an upper layer (i.e., a liquid storage layer) 242a and a lower layer (i.e., an acquisition layer) 242b beneath the storage layer 242a. The topsheet 238 and the storage layer 242a have an opening 200 through which a portion of the acquisition layer 242b is exposed. The exposed portion is preferably above the body contacting surface 22 of the topsheet 238 thereby forming a hump 210. The hump 210 forms a part of the body contacting surface 22 of the sanitary napkin 220.

A topsheet 38 which is particularly suitable for use in the sanitary napkin 20 includes an apertured formed film. Apertured formed films are preferred for the topsheet because they are pervious to body exudates and, if properly apertured, have a reduced tendency to allow liquids to pass back through and rewet the wearer's skin. Thus, the body side surface of the formed film (i.e., the body contacting surface of the sanitary napkin) remains dry, thereby reducing body soiling and creating a more comfortable feel for the wearer. Suitable formed films are described in U.S. Patent 3,929,135, entitled "Absorptive Structures Having Tapered Capillaries", which issued to Thompson on December 30, 1975; U.S. Patent 4,324,246 entitled "Disposable Absorbent Article Having A Stain Resistant Topsheet", which issued to Mullane, et al. on April 13, 1982; U.S. Patent 4,342,314 entitled "Resilient Plastic Web Exhibiting Fiber-Like Properties", which issued to Radel, et al. on August 3, 1982; U.S. Patent 4,463,045 entitled "Macroscopically Expanded Three-Dimensional Plastic Web Exhibiting Non-Glossy Visible Surface and Cloth-Like Tactile Impression", which issued to Ahr et al. on July 31 , 1984; U.S. Patent 4,780,352 entitled "Covering Structure For Absorbent Hygienic Sanitary Products, and an Absorbent Product Having Such A Covering", which issued to Palumbo on October 25, 1988; U.S. Patent 5,006,394 "Multilayer Polymeric Film" issued to Baird on April 9, 1991 ; and U.S. Patent Application Serial No. 08/442,935 entitled "Fluid Transport Webs Exhibiting Surface Energy Gradients" filed in the name of Ouellette, et al. on May 31 , 1995 (International Publication No. WO 96/00548, published January 11 , 1996).

In a preferred embodiment, the topsheet 38 includes an apertured formed film made in accordance with U.S. Patents 4,342,314 issued to Radel, et al. and 4,463,045 issued to Ahr, et al., which is marketed on sanitary napkins as the DRI- WEAVE topsheet by The Procter & Gamble Company of Cincinnati, OH. Such an apertured film is preferably obtained as product No. X-5652 from Tredegar Film Products of Terre Haute, IN. In this preferred embodiment, during manufacture the resin used to form the apertured film is preferably provided with a surfactant incorporated therein.

In preferred embodiments, the body side surface of the topsheet 38 is hydrophilic so that liquids will be transferred through the topsheet more readily. If the topsheet is made of a hydrophobic material, at least the upper surface of the topsheet is treated to be hydrophilic so that liquids will transfer through the topsheet more rapidly. This diminishes the likelihood that menstrual fluid will flow off the topsheet rather than flowing into and being absorbed by the absorbent body. The body side surface of the topsheet 38 can be made hydrophilic by treating it with a surfactant. Suitable methods of treating a topsheet with a surfactant are described in U.S. Patent 4,950,254 issued to Osborn; U.S. Patents 4,988,344 entitled "Absorbent Articles with Multiple Layer Absorbent Layers" issued to Reising, et al on January 29, 1991 ; and U.S. Patent 4,988,345 entitled "Absorbent Articles with Rapid Acquiring Absorbent Cores" issued to Reising on January 29, 1991.

A backsheet 40 which is particularly suitable for use in the sanitary napkin 20 includes a polyethylene film having a thickness of from about 0.012 mm (0.5 mil) to about 0.051 mm (2.0 mils) as stated above. A suitable backsheet material is obtained as product No. 18-1401 from the Clopay Corporation of Cincinnati, Ohio. A suitable breathable backsheet material is a laminate of an apertured film such as that described in U.S. Patent 3,929,135 issued to Thompson which is inverted so that the smaller openings of the tapered capillaries face the absorbent body 42 which is adhesively laminated to a microporous film such as that described in Exxon's U.S. Patent 4,777,073.

In a preferred embodiment, the absorbent body 42 includes a fibrous material of a nonwoven material which includes about 87% of chemically stiffened cellulosic fibers (air laid) which are coated or impregnated with a citric acid, and about 13% of bi-component fibers which have a polyethylene in the sheath and a polypropylene in the core. This nonwoven material has a basis weight of about 150 g/m² and a dry density of about 0.03 g/cm³. In this embodiment, the body contacting surface 22 of the sanitary napkin 20 has the resilient property which is depicted by the curves 51 and 52 in Fig. 5. In Fig. 5, the horizontal axis shows the depth D (mm) from the original body contacting surface 22, while the vertical axis shows the resilient force F (gf) generated at applied depth D. The curve 51 shows the changes of the resilient force F when the depth D increases, while the curve 52 shows the changes when the depth D decreases. Specifically, in this embodiment at least a portion of the body contacting surface has a resilient force of about 1 Λ gf at 3 mm in depth and about 27.2 gf at 5 mm in depth. Additionally, in this embodiment at least a portion of the body contacting surface has a resilient hysteresis of about 20.3 gf-mm in a compressive depth range between about 0 mm and about 5 mm.

In an alternative preferred embodiment, the absorbent body 42 includes a fibrous material of a nonwoven material which includes air laid component fibers of about 10% of cellulose fibers and about 90% of bi-component fibers. The bi- component fibers have about 2 denier, and have a polyethylene in the sheath and a polypropylene in the core. The fibrous material has a basis weight of about 200 g/m² and a dry density of about 0.03 g/cm³. In this embodiment, the body contacting surface 22 of the sanitary napkin 20 has the resilient property which is depicted by the curves 53 and 54 in Fig. 5. The curve 53 shows the changes of the resilient force F when the depth D increases, while the curve 54 shows the changes when the depth D decreases. Specifically, in this embodiment at least a portion of the body contacting surface has a resilient force of about 5.9 gf at 3 mm in depth and about 17.4 gf at 5 mm in depth. Additionally, in this embodiment at least a portion of the body contacting surface has a resilient hysteresis of about 13.2 gf-mm in a compressive depth range between about 0 mm and about 5 mm.

In an yet alternative preferred embodiment, the absorbent body 42 includes a polymeric foam. The polymeric foam which is suitable for this embodiment is disclosed in U.S. Patent 5,899,893 issued to Dyer et al. on May 4, 1999. In this embodiment, the body contacting surface 22 of the sanitary napkin 20 has the resilient property which is depicted by the curves 55 and 56 in Fig. 5. The curve 55 shows the changes of the resilient force F when the depth D increases, while the curve 56 shows the changes when the depth D decreases. Specifically, in this embodiment at least a portion of the body contacting surface has a resilient force of about 6.9 gf at 3 mm in depth and about 10.6 gf at 5 mm in depth. Additionally, in this embodiment at least a portion of the body contacting surface has a resilient hysteresis of about 10.8 gf-mm in a compressive depth range between about 0 mm and about 5 mm.

In a still alternative preferred embodiment, the absorbent body 42 includes a fibrous material which includes loose fibers which form a mat of polypropylene fibers. The loose fibers have about 2 denier and have a dry density of about 0.01 g/cm³. In this embodiment, the body contacting surface 22 of the sanitary napkin 20 has the resilient property which is depicted by the curves 57 and 58 in Fig. 5. The curve 57 shows the changes of the resilient force F when the depth D increases, while the curve 58 shows the changes when the depth D decreases. Specifically, in this embodiment at least a portion of the body contacting surface has a resilient force of about 2.6 gf at 3 mm in depth and about 4.7 gf at 5 mm in depth. Additionally, in this embodiment at least a portion of the body contacting surface has a resilient hysteresis of about 2.3 gf-mm in a compressive depth range between about 0 mm and about 5 mm. The topsheet 38, the backsheet 40, and the absorbent body 42 may be assembled in a variety of configurations known in the art (including layered or "sandwich" configurations and wrapped or "tube" configurations). As shown in Fig. 2, the sanitary napkin 20 is assembled in a sandwich construction. The topsheet 38 and the backsheet 40 have length and width dimensions generally larger than those of the absorbent body 42. The topsheet 38 and the backsheet 40 extend beyond the edges of the absorbent body 42 to form portions of the periphery 30. The garment side surface of the topsheet 38 is preferably joined to the body side surface of the absorbent body 42. If the absorbent body 42 has a layered structure, each layer may be joined each other, if desired. If these components are joined, they can be joined in any of the manners described hereinabove. The backsheet 40 is preferably joined to the garment side surface of the absorbent body 42 by adhesives.

The portions of the topsheet 38 and backsheet 40 that extend beyond the edges of the absorbent body 42 are preferably also joined to each other. Preferably, in the embodiment shown, these portions of the topsheet 38 and backsheet 40 are joined using adhesives over substantially the entire portions that extend beyond the edges of the absorbent body 42 and a crimp seal at the end edges 28 of the sanitary napkin 20 where the topsheet 38 and backsheet 40 are densified by the application of pressure or heat and pressure. The sanitary napkin 20 can include an optional pair of flaps (not shown in

Figs.). The flaps extend outward from at least the central region 36 of the sanitary napkin 20. The flaps can be in any suitable configuration. Suitable flaps are described in Reexamined Patent No. B1 4,589,876 entitled "Sanitary Napkin", issued to Van Tilburg, Certificate of Reexamination issued April 27, 1993; U.S. Patent 4,687,478 entitled "Shaped Sanitary Napkin With Flaps", which issued to Van Tilburg on August 18, 1987; U.S. Patent 5,389,094 entitled "Absorbent Article Having Flaps and Zones of Differential Extensibility" issued to Lavash, et al. on February 14, 1995; U.S. Patent 5,558,663 entitled "Absorbent Article Having Undergarment Covering Components With Zones of Extensibility" issued to Weinberger, et al. on September 24, 1996 (which describes an alternative to flaps that are applied by the wearer); and in International Patent Application Serial No. PCT US 96/15957 entitled "Absorbent Article Having Flaps With Step Configuration and Zones of Extensibility" filed on October 3, 1996, in the name of Lash, et al.

The garment contacting surface 24 of the sanitary napkin 20 may include, and preferably does include, fasteners for attaching the sanitary napkin to the wearer's undergarment. Fig. 2 shows the central pad fastener 82 which is adapted to secure the sanitary napkin to the crotch region of an undergarment. Any types of fasteners known in the art, such as adhesive fasteners and mechanical fasteners can be used. Fasteners comprising adhesives have been found to work well for this purpose, with pressure-sensitive adhesives being preferred. In a preferred embodiment, the central pad fastener 82 includes a pair of spaced apart longitudinally-oriented strips or zones (not shown in Figs.) of adhesive that are centered about the longitudinal centerline L.

The outer surface of the flaps, adjacent the distal edges of the flaps, is preferably provided with a flap adhesive. The flap adhesive is used to assist in maintaining the flaps in position after they are wrapped around the edge of the crotch portion of the panty. Suitable adhesive fasteners are described in greater detail in U.S. Patent 4,917,697. The flaps can be maintained in position by attaching the flaps to the undergarment, or to the opposing flap.

The fasteners are not limited to adhesive attachment means. Any type of fastener used in the art can be used for such purpose. For example, the sanitary napkin 20 could be secured to the wearer's undergarment by mechanical fasteners, such as VELCRO, or the fasteners described in U.S. Patent 4,946,527 entitled "Pressure-Sensitive Adhesive Fastener and Method of Making the Same" issued to Battrell on August 7, 1990, or U.S. Patent 5,392,498 entitled "Non-Abrasive Skin Friendly Mechanical Fastening System" issued to Goulait, et al. on February 28, 1995. For simplicity, however, the fasteners will be described in terms of adhesive attachment means.

The adhesive attachment means are respectively covered by removable release liners, central pad release liner and flap release liner. For example, in the embodiment shown in Fig. 2, a release liner 86 is provided to protect the adhesive attachment means of the fastener 82 before use. The pressure-sensitive adhesives should be covered with release liners to keep the adhesives from sticking to extraneous surfaces prior to use. Suitable release liners are described in U.S. Patent 4,917,697. A particularly preferred release liner which also serves as an individual package for wrapping the sanitary napkin is described in U.S. Patent 4,556,146 issued to Swanson, et al.

Fig. 6 is a transverse cross-sectional view of a human female wearer who wears the sanitary napkin 20 shown in Figs. 1 and 2. Referring to Fig. 6, the urogenital members of the wearer include the labia minora N including the interior surface of the labia minora Nl and the exterior surface of the labia minora NE, and the labia majora J. The interior surface Nl of the labia minora N continuously extending from the vaginal introitus VI. Therefore, body fluid such as menses is known to be eventually discharged through the space between the interior surfaces Nl of the labia minora N. In this embodiment, since the body contacting surface 200 of the sanitary napkin 20 is compressible and/or resilient enough than the skin/flesh of a wearer's perineum or urogenital area (e.g., a labia area), it can conform closely to the wearer's body thereby improving intimate contact between the wearer's skin and the body contacting surface of the sanitary napkin 20 even when the position of the sanitary napkin 20 changes by the movement of the wearer. Thus, this provides less opportunity for body discharges to escape leading to leakage, and provides improved wearing comfort.

In a preferred embodiment, the body contacting surface 200 more reliably contacts the interior surfaces Nl and/or the exterior surfaces NE of the wearer. The improved contact of the body contacting surface 200 with the interior surfaces Nl can provide an opportunity to intercept the body fluid flowing through the space between the interior surfaces Nl, and directly acquires body fluid from there before the body fluid reaches the surface of the wearer's body outside the labia minora. In addition the contact of the body contacting surface 200 with the exterior surfaces NE also provides an opportunity to acquire body fluid discharged through the space between the interior surfaces Nl of the labia minora N before body fluid reaches the surface of the wearer's body outside the labia minora.

Numerous other embodiments of the sanitary napkin 20 are possible. For example, the main body portion of the sanitary napkin can be provided in the form of a compound sanitary napkin that has its components bonded as described herein for improved integrity and acquisition. General descriptions of compound sanitary napkins are found in P&G's U.S. Patent 4,425,130 entitled "Compound Sanitary Napkin" issued to DesMarais, et al. on January 10, 1984, and in Statutory Invention Registration H1614 entitled "Body Fitting Compound Sanitary Napkin", published in the name of Mayer, et al. on November 5, 1996. To form the compound sanitary napkin, a sanitary napkin such as that described herein can serve as the panty protector (or "base pad") and a tube of absorbent material wrapped by a topsheet (or "primary menstrual pad") can be placed on top of the sanitary napkin and attached thereto at the ends. The fusion bonding on the base pad is preferably distributed in the same manner as shown on the drawings herein. The attachment of the tube to the sanitary napkin is preferably achieved by fusion bonding extensions of the topsheet material at the ends of the tube to the base pad. In some preferred embodiments of such a compound sanitary napkin, there may also be attachment between the ends of the tube of absorbent material and the base pad. The tube of the compound sanitary napkin can be attached to the base pad between its ends by any suitable attachment means, such as by adhesives.

The present invention can be applied to other types of absorbent articles than the sanitary napkin. Such absorbent articles include, but not limited to, tampons, interlabial absorbent articles, panti-liners, incontinence articles, diapers including infant and adult diapers, training pants, and the like.

Herein, "tampon" refers to any type of absorbent structure which is inserted into the vaginal canal or other body cavities for the absorption of fluid therefrom. The basic tampon structures are described in U.S. Patents 1 ,926,900 issued to Haas on September 12, 1933; U.S. Patent 1,946,911 issued to Haas on July 3, 1934; and U.S. Patent 3,322,123 issued to Giswold, et al. on May 30, 1967.

Herein, "interlabial absorbent article" refers to an absorbent device that is insertable into the interlabial space of a female wearer for catamenial purposes, incontinence protection, or both. Suitable interlabial absorbent articles are disclosed in, e.g., U.S. Patent 5,762,644 entitled "Toilet-Disposable Absorbent Interlabial Device" issued to Osborn, et al. on June 9, 1998; International Publication No. WO

98/29078 entitled "Thin Comfortable Interlabial Absorbent Structure" published in the name of Osborn, et al. on July 9, 1998; U.S. Patent Des. 404,814 entitled "Interlabial Absorbent Device" issued to Mayer on January 26, 1999; U. S. Application Serial No. 09/071 ,425, filed on May 1 , 1998 in the name of Brown, et al. Herein, "panty liner" or "panti-liner" refer to absorbent articles that are less bulky than sanitary napkins which are generally worn by women between their menstrual periods. Suitable absorbent articles are disclosed in, e.g., U.S. Pat. No. 4,738,676 entitled "Pantiliner" issued to Osborn on Apr. 19, 1988.

Herein, "incontinence article" refers to pads, undergarments (pads held in place by a suspension system of same type, such as a belt, or the like), inserts for absorbent articles, capacity boosters for absorbent articles, briefs, bed pads, and the like regardless of whether they are worn by adults or other incontinent persons. Suitable incontinence articles are disclosed in, e.g., U.S. Patent No. 4,253,461 issued to Strickland, et al. on March 3, 1981 ; U.S. Patent Nos. 4,597,760 and 4,597,761 issued to Buell; the above-mentioned U.S. Patent No. 4,704,115; U.S. Patent No. 4,909,802 issued to Ahr, et al.; U.S. Patent No. 4,964,860 issued to Gipson, et al. on October 23, 1990; and in U.S. Patent Application Serial No. 07/637,090 filed by Noel, et al. on January 3, 1991 (International Publication No. WO 92/11830 published on July 23, 1992).

Herein, "diaper" refers to an absorbent article generally worn by infants, and incontinent persons that is worn about the lower torso of the wearer. Suitable diapers are disclosed in, e.g., U.S. Patent 3,860,003 issued to Buell on January 14, 1975; U.S. Patent 5,151 ,092 issued to Buell et al. on September 29, 1992; U.S. Patent 5,221 ,274 issued to Buell et al. on June 22, 1993; and U.S. Patent 5,554,145 issued to Roe et al. on September 10, 1996. Herein, "training pants" refers to disposable garments having fixed sides and leg openings. Training pants are placed in position on the wearer by inserting the wearer's legs into the leg openings and sliding the training pant into position about the wearer's lower torso. Suitable training pants are disclosed in, e.g., U.S. Patent No. 5,246,433, issued to Hasse, et al. on September 21 , 1993.

Test Method

This method describes a procedure that is used for determining a resilient force and a resilient hysteresis against an externally applied compression. In general, this procedure involves a measurement of change of a resilient force which is generated when a sample absorbent article or material is pushed down by a predetermined probe at the probe contacting area. The test apparatus comprises a horizontal, smooth and rigid plate and a vertically movable arm which is positioned above the horizontal plate. The plate should be made of stainless steel or other rigid, non-corrosive metal. A preferred plate is a stainless steel plate. A sample absorbent article or material is placed and fixed on the horizontal plate such that the body contacting surface of the article is exposed.

A probe which has a predetermined top shape is attached to the arm so that the top of the probe will contact about the center of the body contacting surface of the article (i.e., the probe contacting area). The top of the probe has a half sphere metal ball having a radius of about 2 mm. The half sphere metal ball is mounted at the center of the top of the probe. The probe is connected to a pressure sensor which measures, through the probe, the resilient force generated from the body contacting surface of the article at the probe contacting area.

The arm is taken down at a cross-head speed of about 3 mm per second until the depth of the probe from the body contacting surface of the article or material at the probe contacting area becomes 5 mm. Upon reaching to the depth of 5 mm, the arm is then returned toward the original depth by taking it up at the same head speed. The resilient force which is measured by the sensor is continuously recorded by a recorder (e.g., a computer system). Measurements are repeatedly conducted at least 3 times for one identical probe contacting area and the average value of the resilient force change between 0 mm and 5 mm in depth are obtained from the recorded data. Based on the average data, a graph of hysteresis curve is obtained. Fig. 5 shows examples of such a graph. A preferred test apparatus for the measurements is available from Axion Co.,

Ltd., Koriyama, Japan, under the trade name "Venustron".

Based on the recorded data, a resilient force value and a resilient hysteresis value are obtained as follows:

(1 ) Resilient Force Value This is determined by the average resilient force value at a given depth (e.g.,

3 and 5 mm) of penetration of the probe when the depth increases.

(2) Resilient Hysteresis Value

This is determined by the average area which is enclosed by a hysteresis curve in the resilient force vs. depth of penetration graph. Values are quoted for a hysteresis from 0 mm to 5 mm and returning to 0 mm of the depth of the probe. It is understood that the examples and embodiments described herein are for illustrative purpose only and that various modifications or changes will be suggested to one skilled in the art without departing from the scope of the present invention.

Claims

WHAT IS CLAIMED IS:

1. An absorbent article having a body contacting surface, wherein at least a portion of the body contacting surface has a resilient force which is less than about 20 gf at 3 mm in depth, about 40 gf at 5 mm in depth, or about 100 gf at 10 mm in depth.

2. The absorbent article of Claim 1 , wherein at least a portion of the body contacting surface has a resilient force which is less than about 20 gf at 3 mm in depth, about 40 gf at 5 mm in depth, and about 100 gf at 10 mm in depth.

3. The absorbent article of Claim 1 , wherein at least a portion of the body contacting surface has a resilient hysteresis of less than about 30 gf-mm in a compressive depth range between about 0 mm and about 5 mm.

4. The absorbent article of Claim 1 , wherein the absorbent article comprises a polymeric foam material which forms the portion of the body contacting surface.

5. The absorbent article of Claim 1 , wherein the absorbent article comprises a topsheet which forms the portion of the body contacting surface, a backsheet which forms the portion of the garment facing surface, and an absorbent body disposed between the topsheet and the backsheet.

7. The absorbent article of Claim 5, wherein the absorbent body includes a polymeric foam material.

8. The absorbent article of Claim 5, wherein the absorbent body includes a fibrous material.

9. The absorbent article of Claim 1 , wherein the portion of the body contacting surface has a hump.

10. An absorbent article, comprising: a topsheet having a body contacting surface and an opening; a backsheet having a garment facing surface; and an absorbent body disposed between the topsheet and the backsheet, the absorbent body having a portion exposed through the opening and above the body contacting surface of the topsheet; wherein the exposed portion of the absorbent body has a resilient force at 5 mm in depth of less than about 150 gf.