WO2001045622A1

WO2001045622A1 - Sanitary absorbent article having tear resistant flaps

Info

Publication number: WO2001045622A1
Application number: PCT/CA2000/001542
Authority: WO
Inventors: James P. Barr
Original assignee: Johnson & Johnson Inc.
Priority date: 1999-12-22
Filing date: 2000-12-19
Publication date: 2001-06-28
Also published as: AU2495301A

Abstract

A disposable absorbent article, such as a sanitary napkin with tear resistant side flaps. More particularly, the sanitary napkin having side flaps and a tear resistant stress relief element concave slits or notches for relieving the stresses that develop in the flaps when the flaps are folded over the edges of a crotch portion of a wearer's undergarment.

Description

SANITARY ABSORBENT ARTICLE HAVING TEAR RESISTANT

FLAPS

FIELD OF THE INVENTION

The present invention relates to disposable absorbent articles, such as sanitary napkins with tear resistant side flaps. More particularly, the invention relates to a sanitary napkin having side flaps and a tear resistant stress relief element for relieving the stresses that develop in the flaps when the flaps are folded over the edges of a crotch portion of a wearer's undergarment.

BACKGROUND OF THE INVENTION

Sanitary napkins having side flaps are disclosed in the literature and are generally available in the marketplace. Generally, the flaps extend laterally from a central absorbent core and are intended to drape over the edges of the wearer's panties in the crotch region. Thus, the flaps are disposed between the edges of the wearer's panties in the crotch region and the wearer's thighs. Commonly, the flaps are provided with an attachment means for affixing the flaps to the underside of the wearer's panties.

The flaps serve at least two purposes. First, the flaps prevent exudates from soiling the edges of the wearer's panties and second, the flaps, when affixed to the underside of the panties, help stabilize the napkin in the undergarment and prevent it shifting out of place.

Sanitary napkins having flaps are disclosed in U.S. Pat. No. 4,687,478, entitled "Shaped Sanitary Napkin With Flaps", to Van Tilburg on Aug. 18, 1987,

U.S. Pat. No. 4,608,047, entitled "Sanitary Napkin Attachment Means", to Mattingly on Aug. 26, 1986, U.S. Pat. No. 4,589,876, entitled "Sanitary Napkin", to Van Tilburg on May 20, 1986, U.S. Pat. No. 4,285,343, entitled "Sanitary Napkin", to McNair on Aug. 25, 1981 , U.S. Pat. No. 3,397,697, entitled "Disposable Sanitary Shield For Undergarments", to Rickard on Aug. 20, 1968, U.S. Pat. No. 2,787,271 , entitled "Sanitary Napkin", to Clark on Apr. 2, 1957 and U.S. Pat. No. 4,900,320, entitled "Sanitary Napkin With Panty Gathering Flaps, to McCoy on Feb. 13, 1990, all of which are incorporated herein by reference in their entirety.

While sanitary napkins having flaps are commonly viewed as providing better protection against soiling as compared to sanitary napkins without flaps, these napkins commonly experience a problem that keeps them from being optimally effective. The problem is that as the flaps become longer to protect more of the undergarment from being soiled, the flaps have a greater tendency to become detached from the underside of the wearer's panties. That is, when the flaps are folded down over the edges of the wearer's panties, stresses are created in the flaps. The stresses are especially high along the fold line at the edges of the wearer's panties where the flaps are bent from the bodyside of the panty to the underside of the panty. These stresses are magnified when a wearer sits or crouches because the edges of the panties are pulled outwards against the flaps thus increasing the forces against this fold line. When the stresses become too high, the flaps may become detached from the panty and some portion of the aforementioned benefits of the flaps may be lost.

To overcome this problem, it has been suggested to provide the flaps with stress relief means in the form of slits or notches along the side edges of the flaps where the edge is intended to contact the undergarment. For example, U.S. Pat. No. 4,917,697,entitled "Shaped Sanitary Napkin Having Flaps and Stress Relief Means", to Osborn on Apr. 17, 1990, which is incorporated herein by reference in its entirety, teaches a sanitary napkin flaps with stress relief means in the form of slits or notches in flaps. However, these slits or notches have been found to contribute to the propagation of a fissure through the material of the flap, by virtue of the shear stress concentration phenomenon. Indeed, when stress is applied to the flap, the stress levels in the area of the slit or notch are magnified substantially and this may contribute to tear the material locally. The resulting fissure, propagates through the material and may cause the flap to partially or fully separate from the sanitary napkin.

SUMMARY OF THE INVENTION

5

It is an object of the present invention to provide a sanitary absorbent article having tear resistant flaps and in particular a sanitary napkin having flaps with a tear-resistant stress relief element for relieving the stresses that develop in at least one flap when it is folded over the edges of the wearer's panties in the crotch l o and affixed to the underside of the panties.

In accordance with the present invention, there has been provided a sanitary absorbent article having side flaps that are adapted to be folded over a crotch portion of a wearer's undergarment when in use. Examples of sanitary absorbent articles

15 include, but are not limited to sanitary napkins, panty liners or incontinence devices that are adapted to be worn in a user's undergarment. The flaps have a slit or notch to reduce stresses that may develop in the flap when placed in the wearer's undergarment. The slit or notch has a point of origin characterized by a circular geometrical shape that reduces or eliminates the likelihood of tearing when stresses

20 are imparted to the sanitary absorbent article by the wearer's undergarment.

In a specific embodiment of the invention, the point of origin of the slit or notch is enlarged in the form of a radial aperture, such that the boundary defining the aperture is generally circular in form. As used herein, the term "circular" refers to 5 any arcuate shape formed from one or more continuous arcs defining the peripheral boundary of the aperture and includes oval, egg-shaped or any other suitable curved geometric shape that reduces the risk of fissure generation and propagation.

The slit or notch is preferably located in tr e area of the flap where it joins the 0 main body of the sanitary napkin, commonly referred to as a line of juncture.

Alternatively, the slit or notch can be outward fro n the line of juncture, at a position intermediate a proximal end of the flap and an opposite distal end of the flap. Not only does the slit or notch .'.ct as a stress relief element for relieving the stresses that develop in the flap when the flap is folded over the edges of the wearer's panties, but at the same time, the slit or notch having a circular point of origin is tear-resistant such that at the levels of stress applied to the flap during normal use of the sanitary napkin a fissure or tear line is unlikely to develop.

These and other flaps of the present invention will be more readily apparent when considered in reference to the following description and when taken in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are provided for purposes of illustration only and not as a definition of the boundaries of the invention, for which reference should be made to the appending claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGURE 1 is a top plan view of a sanitary napkin according to the present invention.

FIGURE l a is schematic view of a slit of the sanitary napkin of Figure 1 , featuring an enlarged point of origin that is tcar-resistant.

FIGURE 2 is a lateral cross-sectional view of the sanitary napkin shown in FIGURE 1 taken along line 2-2 of FIGURE 1.

FIGURE 3 is a perspective view of the crotch portion of a wearer's panties.

FIGURE 4 is the same perspective view of the wearer's panties shown in FIGURE 3 with the sanitary napkin embodiment of FIGURE 1 being in place therein for use. FIGURE 5 is a top plan view of another sanitary napkin embodiment of the present invention.

FIGURE 6 is a top plan view of still another sanitary napkin embodiment of the present invention.

DETAILED DESCRIPTION

The present invention relates to sanitary absorbent articles such as sanitary napkins, panty liners or incontinence devices among others, having side flaps with a tear- resistant slit or notch in their construction. Such tear-resistant slit or notch allows the side flaps to better resist stresses imparted to them during their placement in the crotch portion of the wearer, during use and also during removal from the crotch portion of the wearer.

In a specific example of implementation, the sanitary absorbent article is a sanitary napkin with flaps. The tear-resistant slit or notch is provided in the flaps to reduce the likelihood of the flaps separating from the main body of the sanitary napkin in use.

As used herein, the term "sanitary napkin" refers to an article which is worn by females in an undergarment adjacent to the pudendal region and which is intended to absorb and contain the various exudates which are discharged from the body (e.g., blood menses, and urine) and which is intended to be discarded after a single use (i.e., it is not intended to be laundered or otherwise restored or reused).

A specific example of implementation of a sanitary napkin according to the present invention is illustrated in FIGURE 1 . The sanitary napkin designated by the reference numeral 210 basically comprises a main body represented by central absorbent pad 212 and two flaps 224 and 224' extending laterally outward from the longitudinal side edges of the central absorbent pad 212 in a central portion thereof.

(In the discussion that follows, unless otherwise noted, the sanitary napkins will have two flaps. While it is not necessary that the napkins have two flaps, two flaps are preferred over one flap. Also, while it is not necessary that the flaps be mirror images of one another they preferably are. Thus, the description of one flap will be a description of the other, and, for clarity, discussion of the second flap will be omitted).

Flap 224 is associated with central absorbent pad 212 along a line of juncture 226. As used herein, the term "line of juncture" refers to any of various curved or straight lines. Flap 224 has a distal edge 278 that is remote from a proximal edge defined by the line of juncture 226. In the embodiment illustrated in FIGURE 1 , line of juncture 226 is concave relative to the distal edge 278. That is to say, line of juncture 226 curves away from distal edge 278. In this embodiment, lines of juncture 226 and 226' and seam 239 define an absorbent core (central absorbent pad 212) which is narrower in its central region than at its ends. A sanitary napkin narrower in the center than at the ends is generally perceived by the user as more comfortable than a sanitary napkin or uniform width.

FIGURE 2, a cross-sectional view of sanitary napkin 210 taken along line 2- 2 of FIGURE 1 , illustrates generally a preferred construction for sanitary napkin 210. As shown in FIGURE 2, central absorbent pad 212 comprises absorbent core

216. Central absorbent pad 212 and flap 224 both comprise topsheet 214. Backsheet 218 is disposed on the side of absorbent core 216 and flap 224 opposite that of topsheet 214. In effect, topsheet 214 forms one surface of flap 224 while backsheet 218 forms the other surface, topsheet 214 also forms one surface of central absorbent pad 212, backsheet 218, the other.

In the embodiment illustrated, an optional flap absorbent core 230 is shown interposed between topsheet 214 and backsheet 218. For simplicity of construction, flap absorbent core 230 may extend substantially throughout napkin 210 and may be interposed between absorbent core 216 and backsheet 218 as shown, or alternatively may be disposed between absorbent core 216 and topsheet 214 (not shown). Flap absorbent core 230 provides a means for absorbing menstrual fluid that is not absorbed by, or that is expressed from, absorbent core 216. Flap absorbent core 230 is generally compressible, conformable, and non-irritating to the user's skin. It can be made from any of the materials that can be used to make the absorbent core 216 as described above. Preferably, flap absorbent core 230 is a tissue paper sheet. In a preferred embodiment the flap is constructed only of an extension of the topsheet and backsheet and is substantially free of flap absorbent core (not shown).

Topsheet 214 and backsheet 218 are joined at seam 239 (also commonly referred to as a flange seal) around the entire periphery of sanitary napkin 210. The purpose of this seam is to unite the various elements of the sanitary napkin into a unitary structure. Topsheet 214 is secured to flap absorbent core 230 and backsheet 218 along lines of juncture 226 and 226' by attachment means not illustrated in FIGURE 2.

Illustrated in FIGURE 2 are the adhesive attachment means, namely, central pad adhesive 220 and flap adhesive 236 which are covered by, respectively, central pad release liner 222 and flap release liner 238. These adhesive attachment means are adapted to secure sanitary napkin 210 within the crotch region of an undergarment.

Topsheet 214 is liquid permeable and, when sanitary napkin 210 is in use, is in close proximity to the skin of the user. Topsheet 214 is compliant, soft feeling, and non-irritating to the user's skin. It can be made from any of the materials conventional for this type of use. Non-limiting examples of suitable materials that can be used as topsheet 214 are woven and nonwoven polyester, polypropylene, nylon, and/or rayon fabrics and apertured thermo-plastic films. Apertured formed films are preferred for topsheet 214 because they are pervious to liquids and yet non- absorbent. Thus, the surface of the formed film that is in contact with the body remains dry and is more comfortable to the wearer.

Referring to FIGURE 2, it can be seen th it absorbent core 216 is positioned between topsheet 214 and backsheet 218. AbsorDent core 216 provides the means for absorbing menstrual fluid. Absorbent core 216 is generally compressible, comfortable and non-irritating to the user's skin. It can comprise any material used in the art for such purpose. Examples include comminuted wood pulp that is generally referred to as airfelt, creped cellulose wadding, absorbent foams, absorbent sponges, absorbent hydrogel materials, polymeric fibers, or any equivalent material or combinations of materials.

Backsheet 218 is impervious to liquids and, thus, prevents menstrual fluid from soiling the clothing of the user. Any material used in the art for such purpose can be utilized herein. Suitable materials include embossed or non embossed polyethylene films and laminated tissue.

The portion of the outer surface of backsheet 21 8 that is generally in register with absorbent core 216 is coated with central pad adhesive 220. Central pad adhesive 220 provides an adhesive attachment means for securing central absorbent pad 212 in the crotch portion of a panty. Any adhesive or glue used in the art for such purpose can be used herein, with pressure-sensitive adhesive being preferred. Suitable adhesives are Century A-305IV manufactured by the Century Adhesives Corporation and Instant LO 34-2823 manufactured by National Starch Company. As shown in FIGURE 2, central pad adhesive 220 may be the same width as absorbent core 216. However, the width is not critical and appropriate widths, as well as lengths, can be readily selected by those skilled in the art. The pressure- sensitive adhesive of central pad adhesive 220 should be covered with central pad liner 222 to keep the adhesive from drying out and to keep it from sticking to extraneous surfaces prior to use. Any commercially available release liner commonly used for such purposes can be used herein. Nonlimiting examples of suitable release liners are BL30MG-A SILOXE l/0 and BL 30 MG-A SILOX 4/P/O both of which are manufactured by the Akrosil Corporation.

As can be observed from the foregoing discussion, central absorbent pad 212 is an absorbent core that has a fluid pervious body contacting surface (represented in FIGURE 2 by topsheet 214) and an opposed liquid impervious surface (represented in FIGURE 2 by backsheet 218). It is to be understood that the embodiment illustrated is only one possible embodiment. Other possible embodiments include one in which an absorbent core is essentially completely wrapped with topsheet before it is placed on a backsheet. The absorbent core can also comprise an absorbent layer which possesses sufficient integrity to stand-alone and which is fluid permeable on one surface while the other surface has been treated to render it liquid impervious.

It should be noted that a narrow central absorbent pad 212 is effective because the overall configuration and use of sanitary napkin 210 results in central absorbent pad 212 being maintained in close proximity to the body. Such proximity of central absorbent pad 212 places it precisely where it should be: very near the body at the vaginal opening. Central absorbent pad 212 can then absorb the vast majority of the menstrual fluid (menses) before it has an opportunity to flow along the central absorbent pad 212.

It is to be observed that lines of juncture 226 and 226' are the lines along which flaps 224 and 224' are associated with the absorbent core (represented by central absorbent pad 212); as such they represent lines of demarcation between the absorbent core and the flaps.

Central absorbent pad 212 will generally have an absorbent capacity sufficient to absorb the anticipated total amount of menstrual fluid. Central absorbent pad 212, is preferably narrow, i.e. less than about 75 mm and is preferably thin, i.e. less than about 5 mm in caliper. It has been found that a sanitary napkin having a narrow, thin absorbent core is extremely comfortable to the user. In the embodiment illustrated in FIGS 1 and 2, topsheet 214 serves as a topsheet for flaps 224 and 224'. In general, the flaps do not require a topsheet to enable them to function properly, but the use of a topsheet is preferred. Flap topsheet can be integral with the central absorbent body, as illustrated, or it can be an independent element; the former being preferred. All of the specific physical properties of the topsheet 214 previously described, apply to any flap topsheet that is used. There is, however, no requirement that the flap topsheet be the same material as the topsheet associated with the central absorbent pad. In one possible embodiment, the flap topsheet may be nonwoven material while the topsheet over the central absorbent pad is an apertured polymeric film.

In the embodiment illustrated in FIGURES 1 and 2, backsheet 218 serves as a backsheet for flaps 224 and 224'. The flaps require a backsheet (or more generally, a liquid impervious materials) to enable them to function properly. The flap backsheet can be integral with the absorbent core liquid impervious surface or they can be independent elements. All of the specific physical properties of the backsheet 218 previously described apply to the flap backsheet.

At least a portion of the outer, garment faceable surface of flap 224, in a region adjacent distal edge 278, is coated with flap adhesive 236. Flap adhesive 236 is an adhesive attachment means which is used to assist in maintaining flap 234 in position after it is wrapped around the edge of the crotch portion of the panty as described below. Any adhesive used for central pad adhesive 220 can be used as flap adhesive 236. Also, flap adhesive 236 is covered with a removable flap release liner 238. Any release liner material used for central pad release liner 222 can be used for flap release liner 238.

As shown in FIGURES 1 and 2, topsheet 214 is secured to backsheet along seam 239, also called flange seal. Seam 239 can be formed by any means commonly used in the art for this purpose such as by gluing, crimping, or heat- sealing. Seam 239 is illustrated extending completely around the periphery of sanitary napkin 220; this is a suitable embodiment for ease of construction. (Other means of uniting the various elements can be used.) Flap absorbent core 230 is illustrated as extending into seam 239; this is, likewise in arrangement that results from a simplified construction technique.

The sanitary napkin shown in FIGURES 1 and 2 has a curvilinear line of juncture 226. As shown absorbent core 216 is generally hourglass shaped so as to conform generally to the wearer's thighs. Thus, the line of juncture 226 between the flap 224 and the absorbent core 216 is curvilinear.

The precise shape of flap 224, as well as the overall shape of the sanitary napkin 210 can be selected by those skilled in the art without undue experimentation. In the embodiment illustrated in FIGURE 1 , the flaps are symmetrically disposed along the longitudinal axis of the sanitary napkin; while this is a possible embodiment, it is not a mandatory design flap.

FIGURE 3 is a depiction of the crotch portion 244 of an undergarment of the type commonly worn by many women and well known as a panty. A panty comprises a front section 240, a back section 242, and a crotch portion 244 that joins the front and back sections. The crotch portion 244 comprises two side edges 246 and 246' and center crotch portion 248.

The sanitary napkin of the present invention, such as the one illustrated in FIGURES 1 and 2, is utilized by removing the release liners 222 and 238 and 238' and thereafter placing the sanitary napkin in a panty as shown in FIGURE 4. The center region of central absorbent pad 212 is placed in crotch portion 244 of the panty with one end of central absorbent pad 212 extending towards the front section

240 of the panty and the other end towards the back section 242 and with the backsheet 218 in contact with the inner surface of center crotch portion 248 of the panty. Central pad adhesive 220 maintains central absorbent pad 212 in position. The distal portions of flaps 224 and 224' are folded around, respectively, side edges 246 and 246' of the crotch portion of the panty. Flap adhesive 236 and 236' secure flaps 224 and 224' in such position, thus, flaps 224 and 224' are each folded over themselves with a portion of the panty, including side edges 246 and 246', interposed therebetween.

Having now described a sanitary napkin, the improvement that is the present invention will now be described. As mentioned previously, when the flap 224 is folded down along the edge 246 in the crotch por.ion 244 of the panty, stresses are developed in the flap 224. These stresses are magnified when the width of flap 224 (as used herein "width" refers to a dimension of the flap as measured between a first side and an opposite second side in a direction parallel to the longitudinal center line) is increased in an attempt to cover a substantial portion of the crotch portion of the wearer's panty. These large width flaps, when folded over the curved portion of the crotch region and attached to the panty's underside creates stresses in the flaps, particularly along the side edges of the flap where they are folded over a wider section of the panty. The stresses are further magnified when the panty is pulled up into position and the elastic in the panty edge 246 urges the flap 224 up towards the wearer's body. The stresses are most highly concentrated along a portion of the fold

249 where the outer edge of the flap 224 changes direction and folds over the edge 246 of the panty in the crotch portion 244. Thus, the concentrated stresses in the flap 224 generally follow the arc formed by the edge of the panty in the crotch portion 244. If the stresses are great enough, the flap 224 can become detached from the panty and the flap 224 becomes less than optimally effective. Depending on the design of the sanitary napkin, the arc of concentrated stresses may coincide with the line of juncture 226 between the flap 224 and absorbent core, or may alternatively may be spaced outward form the line of juncture intermediate the line of juncture and the distal edge of the flap. Generally, panties have a crotch width of about 5.0 to about 7.5 centimeters. Thus, if the width of the central absorbent pad is from about

5.0 to 7.5 centimeters wide, the stresses imparted by the edge of the panty will generally be concentrated along the line of juncture. Alternatively, if the width of the central absorbent pad is less than the width of the panty, then the stresses imparted by the edge of the panty will be concentrated outward from the line of juncture. In order to eliminate, or at least reduce these stresses, the sanitary napkin is provided with stress relief means. An example of a stress relief means is the first stress relief means 250. The first stress relief means 250 reduces the stresses along the fold 249 to such a degree that the flap 224 will remain attached to the underside of the panty.

Referring again to FIGURE 1, the first stress relief means 250 is the notch 252. As used herein, the term "notch" refers to a space, indentation, or hollow along the edge of a material or a laminate of materials. The notch possesses two elements of reference, namely a longitudinal centerline and a point of origin. The longitudinal centerline is an imaginary line located generally in the center of the notch and defines a general direction or path along which the notch extends. When the notch is symmetrical, the longitudinal centerline will normally bisect the notch into two identical halves. When the notch is of such geometrical shape that a longitudinal centerline can not be easily found or identified, the longitudinal centerline is established by performing a straight line approximation by laying a line that as much as possible passes along the central portion of the notch. The point of origin of the notch is a location in the flap material into which the notch is made, toward which the sides or edges of the notch converge and meet with one another. The longitudinal centerline of the notch meets with the point of origin. It is considered an important feature of the present invention that the point of origin has a radial or circular shape. The circular shape defines an aperture that preferably has a minimum radius of 2.5 mm, and more preferably has a radius of at least 3 mm, most preferably at least 3.3 mm. As used herein, radius does not necessarily require that the point of origin be a perfect circle. Thus, the point of origin may be formed from a series of arcs, each arc having a respective radius of curvature, and wherein the minimum radius of curvature for any given arc is preferably at least 2.5 mm.

Another possible first stress relief means 250 are the slits 254 shown in the alternative embodiment of a sanitary napkin 210 shown in FIGURE 5. As used herein, the term "slit" refers to a narrow cut wherein two edges of material are adjacent or nearly adjacent one another without being joined to one another. The slit 254 maybe linear or curvilinear. As in the case of the notch, the slit possesses two elements of reference, namely a longitudinal centerline and a point of origin. The longitudinal centerline is an imaginary line located generally in the center of the slit and defining a general direction or path along which the slit extends. When the slit is symmetrical, the longitudinal centerline will normally bisect the slit in two identical halves. When the slit is of such geometrical shape that a longitudinal centerline can not be easily found or identified, the longitudinal centerline is established by performing a straight line approximation by laying a line that as much as possible passes along the central portion of the slit. The point of origin of the slit is a location on the material in which the slit is made, toward which the sides or edges of the slit converge and meet with one another. The longitudinal centerline of the slit meets with the point of origin.

A common trait shared by the stress relief means 250, either a notch 252 or a slit 254 is the presence of a tear-resistant circular point of origin that prevents the propagation of fissures in the material of the sanitary napkin in which the stress relief means are formed. Such fissures may arise as a result of the shear stresses generated in the material during the use of the sanitary napkin. In particular, a slit

254 or notch 252 that does not possess a circular point of origin as above defined has been found to concentrate the shear stresses at its point of origin and as a result induces the formation and the propagation of a fissure in the flaps of the sanitary napkin.

In the case of the notch 252 or the slit 254, forming a circular point of origin of the slit 254 or notch 252 provides the tear-resisting character. This flap is best shown in FIGURE l a that illustrates schematically the notch 252. The longitudinal centerline of the notch is shown at 402. The notch is depicted as being substantially symmetrical, the longitudinal centerline 402 bisects the notch in two halves that are identical; the circular point of origin 500 being depicted as a perfect circle. The longitudinal centerline intersects with the center of the circular point of origin 500. As shown in Figure 1 A, the notch 252 may taper to an entry zone 502 having a width (as measured across the notch) that is less than the diameter of the circular point of origin 500. Alternatively, the notch may have an entry zone that is equal to the diameter of the circular point of origin (not shown). Preferably the width of the entry zone 502 is less than the maximal width (diameter) of the circular point origin measured transversely with relation to the longitudinal centerline 402. The arrow 504 materializes the location where the maximal width of the aperture at the point of origin 500 is measured. In this embodiment of the invention depicted in Figures 1 and la, the notches 252 of the first stress relief means are provided with points of origin 500 that are in the form of round apertures whose diameter may vary as defined above. As previously discussed, the point of origin need not be restricted to an exact circle shape. Ovals, egg-shaped figures can also be considered among many other possibilities.

Because of the numerous possible configurations for the sanitary napkin 210 and the flap 224, the first stress relief means 250 is preferably located at a point where an edge of the napkin 210 intersects an edge 246 of the panty, in use. The points of intersection between the flap 224 and the edge 246 of the panty, which generally coincide with the ends of the fold 249, are the points where the first stress relief means 250 should preferably be located in order to reduce the stresses in the fold 249. Such first stress relief means 250 may be along the line of juncture 249 or outboard of the line of juncture 249 in the flaps 224 and 224'.

For illustration of the discussion that follows, FIGURE 5 shows a sanitary napkin 210 having flaps 224 and 224' wherein flap 224 has a pair of notches 252, and flap 224' has a pair of slits 254. All notches 252 and slits 254 shown in FIGURE 5 have points of origin 500. As shown in FIGURE 5, each flap 224 and 224' has two first stress relief means 250, one on each side 260 of the lateral centerline 300 of the flap. Also, each pair of first stress relief means 250 at each flap 224 and 224' are symmetrical.

As seen in FIGURE 5, the notches 252 and the slits 254 each have a leading edge 262. A leading edge 262 is the edge of a notch 252 or a slit 254, itself, which extends toward the central portion of the absorbent core. In the case of a notch that has two edges the leading edge 262 is the edge nearest the nearest end 255 of the napkin 210. If the edge of the notch 252 is jagged or the slit 254 is curvilinear or other configurations are present, a straight-line approximation of a leading edge 252 is determined. The leading edge 262 has an angle 275 measured from a longitudinal line which intersects the origination point 264 of the leading edge 262 and is parallel to the longitudinal centerline 400 of the napkin. Preferably, the angle 275 is from about 0" to about 145° from longitudinal, more preferably from about 0° to about 80° from longitudinal, and most preferably the range is from about 20° to about 40° from longitudinal. The range from 20° to about 40° has been found to generally approximate the angle formed by the arc of the edge 246 of the panty in the crotch region 244 at the intersection of the flaps but the other referred angles have also been found to reduce stress.

The depth 280 of the leading edge 262 is measured perpendicularly from the time longitudinal line as previously described and is preferably from about 2.0 to about 20.0 millimeters, more preferably from about 3.0 to about 12.0 millimeters, and most preferably from about 4.0 to about 9.0 millimeters.

As seen in FIGURE 5, a second stress relief means 290 is provided along the distal edges 278 and 278' of the flap 224 and 224'. The second stress relief means 290 along the distal edge 278 of the flap 224 is a notch. The second stress relief means 290 along the distal edge 278' of the flap 224' is in the form of a slit. These second stress relief means 290 allow the flaps 224 and 224' to spread when the flaps are folded under the wearer's panties, thus reducing any tensile forces that may develop in the flaps. Preferably, these second stress relief means 290 are located along the lateral centerline 300 of the flaps. Preferably, these second stress relief means 290 extend from about 3.0 to about 30.0 millimeters inwards from the distal edges of the flaps. The second stress relief means 290 also include an enlarged point of origin 500 to resist tearing.

FIGURE 6 is an alternative embodiment of a sanitary napkin 210 of the present invention having an alternatively preferred first stress relief means 250 in the form of a notch 252. This notch also has a point of origin 500. This embodiment of the invention of the present invention provided earlier was made in connection with a sanitary napkin where the slits or notches where located in the areas of the flaps to provide stress relief in those specific locations. In another possible embodiment, the tear resistant flap can be applied to any slit and notch on the sanitary napkin located elsewhere on the sanitary absorbent article.

Such a slit or notch may for example be located at any point of the periphery of the sanitary absorbent product. In another possible variant, the slit or notch is not located at the periphery of the sanitary absorbent article but it is fully contained within the boundary of the sanitary napkin. Specifically, such internal slit or notch is made on a layer of the sanitary absorbent article and point of the slit or notch is located at a certain distance from the boundary of the layer. Under this form of construction, the internal slit or notch has two generally opposite points of origin, each point of origin being enlarged to provide tear-resistance.

Claims

WHAT IS CLAIMED IS:

1. A sanitary absorbent article comprising a central absorbent pad, the central absorbent pad having a pair of opposite longitudinal side edges and a flap extending laterally outward from each longitudinal side edge along a line of juncture, the flap having a slit or a notch, said slit or notch having a longitudinal centerline and a circular point of origin.

2. A sanitary absorbent article as defined in claim 1 , wherein said circular point of origin is formed from one or more continuous arcs, each arc having a radius of at least 2.5 mm.

3. A sanitary absorbent article as defined in claim 1, wherein said sanitary absorbent article is a sanitary napkin having a longitudinal centerline and a lateral centerline and wherein said slit or notch is located in said flap along said line of juncture.

4. A sanitary absorbent article as defined in claim 1 , wherein said sanitary absorbent article is a sanitary napkin having a longitudinal centerline and a lateral centerline and wherein said slit or notch is located intermediate said line of juncture and said lateral centerline.

5. A sanitary absorbent article as defined in claim 1 , wherein said flap has a first side and an opposite second side and wherein the first side and the second side of said flap have said slit or notch.

6. A sanitary absorbent article as defined in claim 3, wherein said slit or notch has a leading edge having an angle of from about 0° to about 145° with relation to the longitudinal centerline of said sanitary napkin.

7. A sanitary absorbent article as defined in claim 1, wherein said slit or notch has a depth of from about 2.0 to about 20.0 millimeters.

8. A sanitary absorbent article as defined in claim 3, wherein said slit or notch has a leading edge having an angle of from about 20° to about 40° with relation to the longitudinal centerline of said sanitary napkin.

9. A sanitary absorbent article as defined in claim 1 , wherein said slit or notch has a depth of from about 3.0 to about 12.0 millimeters with relation to the longitudinal centerline of said sanitary napkin.

10. A sanitary absorbent article as defined in claim 1 , wherein said sanitary absorbent article is a sanitary napkin having a longitudinal centerline and a lateral centerline; said slit or notch being a first slit or a notch, said first slit or notch being located along said line of juncture; and a second slit or notch in said flap, said second slit or a notch being remote from said line of juncture, said second slit or notch having a longitudinal centerline and a point of origin, the point of origin of said second slit or notch includes an entry zone characterized by a width, the point of origin of said second slit or notch defining an aperture having a maximal dimension measured across the longitudinal centerline of said second slit or notch that exceeds the width of the entry zone of said second slit or notch.

1 1. A sanitary absorbent article as defined in claim 10, wherein said second slit or notch is located along said lateral centerline.