MXPA99004369A - Absorbent article with high stiffness - Google Patents

Abstract

The invention relates to an absorbent article such as a sanitary napkin, an incontinence guard, or a panty-liner, which article has a generally elongated shape with a longitudinal direction and a transverse direction and exhibits two side edges (9, 10), two end portions (6, 7),and a crotch portion (8) located between the end portions (6, 7), which article further exhibits a liquid-pervious cover layer (2), intended to be facing the user during use, and a liquid-impervious cover layer (3), intended to be facing away from the user during use. The article comprises at least within the crotch portion (8) a stiffening element (15) of a material with a very high intrinsic stiffness, whereby the article in the crotch portion (8) has an extension in the transverse direction which during use of the article is between 40 mm and 15 mm and preferably is between 20 mm and 35 mm.

Description

ABSORBENT ARTICLE WITH HIGH RIGIDITY FIELD OF THE ART The present invention relates to an absorbent article such as, for example, a sanitary napkin, an incontinence protector or a panty liner, said article having a generally elongated shape with a longitudinal direction and a transverse direction and also has two side edges, two end edges, and also a crotch portion located between the end portions, said article further has a liquid permeable cover layer whose purpose is to meet on the user's side during the use, and also a coating layer impervious to liquids, whose purpose is to be on the opposite side to the user during use. BACKGROUND OF THE INVENTION When an absorbent article is used, such as a sanitary napkin, an incontinence protector, or the like, with a relatively small size and whose purpose is mainly to be able to lodge in the crotch region of a wearer, it is a important problem that the article during the use is deformed by the forces that arise, for example, when the user moves. Since the article is subject to compression between the legs of the wearer, irrigations and rupture are caused in an uncontrolled manner in the absorbent body of the article as well as in its liquid permeable covering layer. Obviously this represents a disadvantage since the wrinkles act as liquid conducting channels, in which the liquid can flow out over the edges of the article. Additionally, ruptures in the absorbent body cause the deterioration of the liquid distribution capacity in the absorbent body, in such a way that the liquid remains in the acquisition region of the article, that is, in the region wetted in the first instance by the liquid . Therefore, the risk of the acquisition region becoming supersaturated with liquid is imminent, which causes an increased risk of leakage. There is also a significant risk that the lateral edges of the article during use bend inwardly onto the liquid-permeable surface, such that the portion of the article directly accessible for the reception and absorption of liquids is considerably reduced. Likewise, the deformation of this type increases the risk of leakage. Another important problem related to the fact that the absorbent article is deformed during use, is that the article wrinkles and deforms and is uncomfortable to use. In the worst case, pronounced sheets are formed and rub against the skin which irritate the skin during use. In the North American patent number 4,217,901, a sanitary napkin comprising a layer of fluff pulp is presented, said layer serves to increase the resistance against the deformation of the sanitary napkin. Unfortunately, a layer of fluff pulp loses its stiffness when wetted, whereby the previously known sanitary napkin exhibits only high stiffness in an initial stage of use. In addition, a loosening of the compressed fluff pulp layer is observed during use, due to the fact that the fibers of the layer break when the sanitary napkin is subjected to stress and pressure forces during use. A further disadvantage with the previously known compressed lint pulp layer is that it does not have substantial elasticity, which implies that a layer that has been cracked or otherwise deformed does not have the capacity to recover its original shape. SUMMARY OF THE INVENTION By means of the present invention, an article of the type discussed in the introduction has been achieved, wherein the disadvantages and problems associated with such previously known articles are substantially eliminated. An article designed in accordance with the present invention is therefore characterized in that said article, at least inside the crotch portion, comprises a stiffening element of a material with a very high intrinsic rigidity, whereby the article at least inside a crotch part has a dimension in the transverse direction which, when employed the article is between 15mm and 40mm and preferably between 20mm and 35mm. Since the article comprises a component with a very high stiffness, the risk of uncontrolled deformation by means of transverse compression has been totally eliminated. The article in accordance with the present invention has primarily the ability to resist compression when subjected to the forces arising from the user during use. According to a preferred embodiment of the invention, the hardening element can be compressed only up to about 80% of its original width during compression of the crotch region in the transverse direction of the article with forces of the magnitude of which they are found. present during use. Measurements have shown that all human beings have a critical area in the groin portion between two muscle groups that extend from the inside bottom of the pelvis down along each of the thighs. The distance between the two groups. of muscles is surprisingly similar for all human beings, regardless of the shape of the body and its weight. Thus, the distance between the thighs of a user is obviously affected by fatness, while the distance between the muscle groups in the crotch region of the user is the same regardless of the fact that the user is thin, normal weight, or present overweight. It has been shown that the factor that determines whether a user presents discomfort in the form of pressure or rubbing against the inner parts of the thighs is if the absorbent article during use has a width that, in the critical area, considerably exceeds the distance between the muscle groups in the groin area. This distance is between approximately 30 mm and 35 mm. In addition, it has been found that an article with a width that, during use, exceeds 40 mm in the critical area, feels uncomfortable on the part of most users. On the contrary, an absorbent article that presses against the fatty tissue or displaces the fatty tissue in the crotch area is uncommonly perceived as uncomfortable. In the case of conventional deformable absorbent articles, the limit space in the crotch region of the wearer causes the articles to be uncontrolledly compressed between the wearer's legs and wrinkled in order to be accommodated in the area of the groin. As for an absorbent article in accordance with the present invention, having a rigidly shaped retention element in the crotch portion, the compression can be carried out only to a limited extent, whereby the possible degree of compression is controlled for the design of the rigid crotch portion. Therefore, it is essential that the width of the absorbent article in the crotch portion during use does not exceed the critical value that can be tolerated by the user. Accordingly, however, it is not necessary that the crotch portion along its entire length have a width that, during use, is less than 40 mm. Since the critical area in the crotch region of the wearer is from about 5 mm to 15 mm in length, it is sufficient that the part of the crotch portion that must fit within this area during use meets the requirement of a maximum width. Accordingly, it is sufficient for the invention that, in the longitudinal direction of the article, there is an area of 5-15 mm in length in the crotch portion within which the width during use of the article is not greater than about 0 mm and preference not greater than about 35mm. An element of adequate stiffness is profiled in the transverse direction of the article and has at least one ridge that extends longitudinallyAccordingly, a longitudinal ridge with a rounded surface can be arranged along each lateral edge of the article at least in the crotch portion. An absorbent article in accordance with the present invention is advantageously equipped with a centrally arranged longitudinally projecting portion. Accordingly, a longitudinal groove may be arranged on each side of the central projecting portion, between it and the side edges of the article. Advantageously, the longitudinal projecting portions are combined with lower height portions, or grooves. Accordingly, the transverse compression in the article in the vicinity of the transition area between the crotch portion and the front portion affects the stiffness of the article during use. Said compression increases the directional effect caused by the stiffening element and counteracts the folding of the front part in relation to the crotch part. Accordingly, the stiffness of an absorbent article largely depends on the shape of the article, particularly on the shape of the stiffening element. Therefore, a stiffening element with arms in the form of ridges or grooves has a higher stiffness, perpendicular to the "extension of the ridges or grooves, than a completely flat material." The arms can be obtained by forming the material In addition, either by reinforcing the material with bands or ribs of a separate material, in addition, the stiffness and resistance to bending and twisting can be increased by providing a cup shape to the material or by means of a greater thickness of As examples of plastics material in terms of which it has been found that they have sufficient bending stiffness and sufficient torsional stiffness in order to achieve the ability to withstand the uncontrolled deformation required for the invention, polyethylene or polypropylene with a layer thickness of at least 0.4 mm can be mentioned.In addition, it is possible to increase the rigidity of the plastic layer. plastic mixing the plastic with talc, chalk or other fillers that increase the rigidity. The stiffness of a material of a plastic film that is suitable for use as a stiffening element in an article in accordance with the present invention must therefore exceed 100 N, measured in accordance with ASTM 4032-82"Circular Bend Procedure" ( circular bending process), said method is described in detail in EP 0336578. In this context, the stiffness of the material refers to the stiffness of a layer of flat material.

Furthermore, it is possible to use plates, rods, construction type skeletons or the like of metal, wood or other stiff materials which do not substantially change their stiffness properties when wetted, and do not break under the action of forces arising during the use of an absorbent article. It is therefore possible to use, for instance, cardboard which has been treated in order to resist ance moistened, for example by coating with plastic or the like in order to prevent the material softens when wetted and the object to increase the hardness of the material and reduce the risk of rupture. It is not absolutely essential for the invention that the rigid element be constituted by a layer of continuous material, but stiffness elements composed of rigid arms, tubes, pins, or the like can also be employed. An element of stiffness that has been found to perform these functions particularly well is a skeletal structure of bent metal rods. Provided that this structure fits well to the anatomy of the wearer, and particularly not exceed widthwise critical in the crotch region of an absorbent article, said metal skeleton can be left completely incompressible by such forces which occur during normal use. When rigid stiffening elements are employed it may be desirable to arrange easily deformable, soft edge portions on both sides along the side edges of the article. Said arrangement allows a certain amount of compression of the article, in the transverse direction and, at the same time, it offers the article comfortable, soft edges. An anatomically designed article in accordance with the present invention is securely and comfortably held in position against the wearer's body during use, without the need for a special fixation device. This implies that the article is not fixed in any way on the wearer's panties, so the risk that the article during use is displaced with the panties and consequently reaches an incorrect position in relation to the body of the user. user is almost completely eliminated. "BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described in more detail with reference to embodiments illustrated in the accompanying drawings. Figure 1 shows a sanitary napkin in accordance with the present invention, Figure 2 shows a section along the line II-III through the sanitary napkin of figure 1, figure 3 shows a section along the line III-III through the sanitary napkin of figure 1, figure 4 shows a towel sanitary according to an alternative embodiment of the invention, Figure 5 shows a section along the line VV through the sanitary napkin of Figure 4, and Figure 6 shows a section along the line VI- VI through the sanitary napkin of Figure 4. DETAILED DESCRIPTION OF THE PREFERRED MODALITIES The sanitary napkin 1, illustrated in Figures 1, 2 and 3, comprises a liquid-permeable coating layer 2, arranged on the side of the sanitary napkin 1 which, during its use, is intended to face the user, a waterproof coating layer of the liquids 3, arranged on the side of the sanitary napkin 1, which, during use , has the purpose of facing the opposite side of the user, and an absorbent body 4, enclosed between the two layers of coating 2,3. The material of the liquid-permeable coating layer 2 can, for example, be a perforated plastic film, a plastic sheet or a textile material, a protected material or a sheet material, for example, a layer of perforated plastic and a protected layer, the plastic specifically a thermoplastic, such as polyethylene or polypropylene. The term "non-woven material" refers to a non-woven fiber fabric. Suitable nonwoven materials may consist of natural fibers such as for example, cellulose or cotton or synthetic fibers such as polyethylene, polypropylene, polyester, polyurethane, nylon or regenerated cellulose. Naturally, it is also possible to use non-woven materials made from fiber blends. The liquid-permeable coating layer 2 must receive and carry the liquid in the absorbent body 4. In addition, the coating layer must be soft and pleasant against the body of the user, and must also be able to avoid what is known as re-wetting, that is to say, that the absorbed body exudate passes back to the skin of the user. For reasons of comfort, and in order to avoid skin irritations, it is important that the surface on the part of the sanitary towel that is in contact with the wearer's skin is kept as dry as possible during use. In addition, a dry surface in the sanitary napkin is considered by the user as fresher and more pleasant during use, and is also from a purely visual perspective and when the sanitary napkin is handled when it should be replaced, more pleasant than a dirty wet surface. It is not necessary for all embodiments of the invention that the liquid permeable coating layer 2 is in fact formed by a layer of separated material. The liquid-permeable coating layer can, for example, constitute an integral part of an absorbent body. Accordingly, it is conceivable to exclude the liquid-permeable coating layer when the absorbent body comprises a layer of absorbent foam. In addition, an absorbent non-woven material can be used, said material can be an integral component of an absorbent body and at the same time constitute a liquid-permeable coating layer. The liquid-impermeable coating layer 3 consists of a material impervious to liquids. Thin plastic films, impervious to liquids, are suitable for this purpose. However, it is also possible to employ materials that are permeable to liquids to begin with but that are equipped with a coating of plastic, resin, or other liquid impervious material. Accordingly, leakage of liquid from the bottom side of the absorbent article is avoided. The liquid-impermeable coating layer 3 can therefore consist of any skin-friendly material that meets the criteria of liquid impermeability. Examples of materials that are suitable as barrier fields are plastic films, non-woven materials and different types of sheet materials. Useful plastic films are, for example, films consisting of polyethylene, polypropylene, or polyester. Optimally, the liquid impervious coating layer 3 can consist of a sheet product of a layer of liquid impervious plastic facing the absorbent body, and a protected layer facing the wearer's underwear. Said construction provides a leak-proof barrier layer with a textile texture. As in the case of the liquid-permeable coating layer 2, it is not necessary for the liquid-impermeable coating layer 3 to be constituted by a separate layer. Accordingly, it is conceivable that the liquid impermeable coating layer 3 constitutes an integral part of the absorbent material, for example, an absorbent foam layer with a liquid impervious surface. The absorbent body 4 can advantageously be constituted primarily by a cellulose fluff pulp. This can be provided in the form of rolls, sacks, or sheets that are cut dry and in a crumbled state are transformed into a pulp mat, with or without addition of what are known as super absorbers, which are polymers with the capacity of absorbing several times its own weight of water or body exudate. Examples of other useful materials are various types of natural fibers, such as, for example, cotton fibers, peat, or the like. Obviously it is possible to use absorbent synthetic fibers or mixtures of natural fibers and synthetic fibers. The absorption material may also include additional components, such as liquid distribution members or binders, such as, for example, thermoplastic fibers which have been heat treated in order to preserve the short fibers and particles as a coherent unit. It is also possible to employ different types of absorbent foam material in the absorbent body 4. The two coating layers 2, 3 are mutually connected outside the absorbent body 4 and form a protruding edge 5 around the entire periphery of the sanitary napkin. The joining of the coating layers can be carried out in any suitable manner, for example, by means of glue, seam, or welding with application of heat or ultrasonically. The sanitary napkin 1 is substantially in the shape of an hourglass and therefore shows a front portion 6, whose purpose is to bend forward in the wearer during use, a back portion 7, intended to be folded backward in the wearer during the use, and an intermediate portion of narrower crotch 8, intended to be applied in the groin area of the wearer. In addition, the sanitary napkin 1 has two concavely curved side edges 9,10, a convexly curved front edge 11, and also a curved rear edge 12 convexly curved without similarly. The division of the sanitary napkin into a front portion 6, a rear portion 7, and a crotch portion 8, should not be understood as if there were precise boundaries between the different portions 6-8, but rather primarily has the purpose of facilitating description of the sanitary napkin, starting from the differences present between the different portions 6-8 according to how they should be placed in relation to the body of a user. Thus, the transition between the different portions 6-8 is not done in predetermined transverse lines, but within transition regions located at a distance of about one third of the length of the sanitary napkin from the front edge 11 and the back edge 12 of the sanitary napkin, respectively. Accordingly, the crotch portion 8 constitutes the part of the sanitary napkin which during use must receive and absorb the main part of the secreted liquid towards the sanitary napkin during use. A stiffening element 15, for example, made of a rigid plastic layer, or a rigid metal plate, is arranged between the liquid impermeable coating layer 3 of the sanitary napkin 1 and the absorbent body 4, and it extends through the front part 6 of the portion of between legs 8 of the sanitary napkin. The stiffening element 15 is spoon-shaped with a cup-shaped part 16 located in the front portion 6 of the sanitary napkin and a flat rectangular portion 17 located in the crotch portion 8. The cup-shaped part 16 of the element of stiffness 15 has substantially the same shape in the plane as the front portion 6 of the sanitary napkin, but is slightly smaller. Accordingly, the portions of the front portion 6 projecting beyond the edge 19 of the stiffening element 15 form a soft, cushioned edge region 18, which partially serves as a seal against leakage, and to partially counteract rubbing. Correspondingly, the flat part 17 of the shape element 15 does not extend to the side edges 9,10 of the sanitary napkin in the crotch portion 8, but rather a narrow, soft and elastic edge region 18 consisting of parts of the two coating layers 2,3 and the absorbent body 4, extends between each respective lateral edge and the corresponding side edges 20, 21 in the stiffening element 15. The cup-shaped part 16 of the stiffening element 15 has an angle in the longitudinal direction of the sanitary napkin in relation to the flat part 17, thus also the front portion 6 of the sanitary napkin 1 has an angle in relation to the crotch portion 8, as can best be seen in figure 2. In order to obtain the desired angle of the sanitary napkin, the stiffening element 15 has been permanently curved or folded along a transverse bending line 22, which is slightly curved in the direction towards the front edge of the sanitary napkin. The angle alpha, between the substantially flat crotch portion 8 of the sanitary napkin and the front portion 6 that rises therefrom, is therefore about 202-502 and preferably about 30 ^. In Figure 2, the alpha angle has been indicated on the external side of the sanitary napkin, ie, the side of the sanitary napkin that the use is intended to face on the opposite side of the wearer. The relevant angle, however, is in fact the angle in the inner part of the sanitary napkin, since it is the internal part that must adapt to the anatomy of the user. In the example shown, it does not matter if the angle is measured in the external part or in the internal part since the obtained value will be the same due to the fact that both the front portion 6 and the crotch portion 8 have the same inclination in the internal part that in the external part. The curved bend line 22 contributes to providing the sanitary napkin with good shape stability and increases the bending stiffness to the stiffening element 15 in the bending line 22, since bending is more easily accomplished along a line straight that along a curved line. Consequently the angle between the cup-shaped part 16 of the stiffening element 15 and its flat part 17 is also maintained when the sanitary towel during use is subjected to the action of forces. In addition, the bending line provides the front portion 6 of the sanitary napkin with a cup appearance, as shown in Figure 3, which is advantageous for fit and for safety against leakage. In a width of the front portion 6 between 80 and 100 mm, the curve of the front portion 6 should not be greater than a maximum deviation h, from a straight transverse line between the side edges 9,10 of the sanitary napkin, it does not exceed about 10 mm in the vicinity of the front edge 11. Accordingly, the front portion 6 of the sanitary napkin has an angle in a direction toward the liquid-permeable coating layer 2, which implies that the front portion 6 is elevated in the direction of the observer, when the sanitary napkin is observed with the liquid-permeable coating layer 2 facing the observer. In addition, the front portion 6 is preferably curved along the longitudinal center line 23 of the sanitary napkin, such that the front portion 6 has a cup shape when viewed from the liquid permeable coating layer. 2. However, the cup shape should not be more marked than the longitudinal centerline deviates by a maximum of 5mm from a straight line extending along the centerline between the transverse bending line 22 and the edge front 11. A particular advantage with the cup-shaped front portion is that it further increases the stability and resistance to deformation of the sanitary napkin. By means of the angle and the cup shape, the compression resistance of the crotch portion (8) of the sanitary napkin is consequently increased. It is an advantage if the angle of the front portion of the sanitary napkin, in a vertical direction from the liquid-permeable coating layer 2, remains during use. This is achieved by making the stiffening element 15 of a material with a stiffness which in this contact must be considered very high. For reasons of comfort, it is therefore necessary that the part of the stiffening element 15 that during the use that is intended for its application in the groin area of the wearer is not so high as to cause discomfort to the user. Therefore, it is essential that the width of the sanitary napkin does not exceed the critical value that can be tolerated by the users. For the sanitary napkin 1 shown in Figure 1, this implies that the width of the flat portion 17 of the stiffening element 15 should not be greater than about 35 mm in an uncompressed condition. Even if the width of the crotch portion 6 of the sanitary napkin in its entirety exceeds 35 mm this, however, is not critical since the soft edge regions 18 around the stiffening element 15 allow some compression and adaptation of the width of the sanitary napkin 1 in accordance with the width of the groin of the user, so that the width of the sanitary napkin after compression does not exceed approximately 40 mm. In addition, the material in the stiffening element 19 can be selected in such a way that the stiffening element itself allows a certain transverse compression within the crotch portion 8. In order to achieve sufficiently high form stability in the portion of crotch 8 the stiffening element must however be sufficiently rigid to withstand compression to more than 80% of its original width during normal conditions of use. In the case in which the stiffening element 19 is constituted by an extremely rigid material such as, for example, during normal conditions of use, a piece of totally non-elastic plastic or a metal plate is especially important to adapt the width of the stiffness element 19 across the critical width of the groin of the user. When a totally non-elastic stiffening element 19 is used, it must therefore not have a width exceeding approximately 30 mm. The sanitary towel 101 illustrated in Figures 4,5 and 6, comprises a liquid permeable coating layer 102 and a liquid impervious coating layer 103, which together enclose an absorbent body 104. The coating layer permeable to the liquids 102, is as in the sanitary napkin 1 illustrated in figures 1, 2 and 3, formed by a flexible, soft, skin-friendly material. The liquid impermeable coating layer 103, however, is constituted by a rigid material, preferably a relatively thick, rigid plastic layer, which forms a hard retaining shell where the absorbent body 104 is placed. The towel Sanitary 101 is designed with a front portion 106 that is wider than a rear portion 107, and with a crotch portion 108 that is narrower than the front portion and the back portion. Due to the high stiffness of the liquid impervious coating layer 103, it is essential that the sanitary napkin has a shape, which, to a large extent, is adapted to the anatomy of the wearer. Accordingly, it is of vital importance that the width of the sanitary napkin at least within the critical area of the crotch portion 108 does not exceed about 40 mm. As mentioned above, the critical area constitutes the part of the sanitary napkin which during use must be placed between the groups of limited space muscles that extend on both sides in the crotch area of the wearer. This area constitutes approximately 5mm to 15mm of the crotch length length 108. In addition, the sanitary napkin 101 has two longitudinal side edges 109, 110, a transverse concave curved front edge 111 and a curved convex transverse trailing edge. 112. The sanitary napkin is designed in such a way that a transverse line 124 extends in the front portion of the crotch portion 108., in the transverse direction of the sanitary napkin, said line intercepts the side edges 109, 110 of the sanitary napkin. At the intersection line 124, the side edges 109, 110 change from inclination in reversion to the longitudinal center line 123, whereby the width of the sanitary napkin increases in a direction towards the front edge 111, so that the front portion 106 has a maximum width, which exceeds the width of crotch portion 108 in transverse cut line 124. Accordingly, the maximum width of front portion 106 is preferably at least double the width of the portion of crotch 108 in the cross-sectional line 124. The inclination of the side edges 109, 110, in the front portion 106 is defined by a beta angle between each respective side edge 109, 110 and a longitudinal line parallel to the centerline 123 , so that beta is comprised between 30 ° and 90 °, and so the width of the crotch portion 108 on the transverse line 124 is between 15 and 45 mm and preferably between 20 and 40 mm. However, if the sanitary napkin has a construction similar to the construction illustrated in Figure 1, the width of the sanitary napkin can reach up to 60 mm. The absorbent body 104 comprises a first portion 104 ', which forms a longitudinal protrusion 113 on the side of the sanitary napkin which in use has the purpose of coping with the wearer. The first portion 104 'consists of a material of high absorption capacity, for example, absorbent fibers such as, for example, cellulose fluff pulp, rayon or the like with or without super absorbent material, absorbent foam or any of the absorbent fiber materials described above. In addition, all conceivable types of mixtures and material layer combinations can be employed. The absorbent body 104 of the sanitary napkin further comprises an absorption layer 104", arranged between the protrusion 113 and the liquid impervious coating layer.The absorption layer 104" may consist of an absorbent non-woven material, fabric or any other of the aforementioned absorbent materials and can, according to the intended use of the sanitary napkin, be designed with a greater or lesser absorption capacity. In the sanitary napkin illustrated in Figures 4-6 the shape of the sanitary napkin is maintained by means of the entire liquid impermeable coating layer 103 which constitutes a retention shell for the absorbent body 104 of the sanitary napkin. As in the case of the sanitary napkin in Figures 1-3, the front portion 106 of the sanitary napkin 101 illustrated in Figures 4-6 has an angle in relation to the crotch portion 108 of the sanitary napkin. The angle alpha between the front portion 106 and the crotch portion 108 has been indicated in Figure 5 as the angle between the inclination of the protrusion along the longitudinal center line 123 of the sanitary napkin, and the inclination of the front portion 106, since it is this internal angle that indicates that also the sanitary napkin adapts to the shape of the wearer's body in the relevant area. The upward folding of the front portion 106 in relation to the crotch portion 108 is not carried out along the marked bending line but presents a continuous curve in the longitudinal direction of the sanitary napkin. Accordingly, the front portion 106 forms a gently rounded cup that is very well adapted to the wearer's anatomy. When the angle alpha is estimated, the curve of the front portion 106 is not taken into account in such a way that the inclination of the front portion is determined in relation to a straight line extending along the longitudinal centerline 123 , from an imaginary transverse border line between the front portion 106 and the crotch portion 108, towards the front edge 111. Accordingly, the exact value of the inclination of the front portion 106 in relation to the crotch portion is not a critical factor but the angle alpha must lie between 20 ° and 50 °. However, it is helpful for the alpha angle to be maintained during use, both when the article is dry and when the article has been hydrated by the body fluid. In Figure 6, a cross section is illustrated through the sanitary napkin 101 illustrated in Figures 4 and 5. As is clearly evident from Figure 6, the side edges 109, 110 of the sanitary napkin are curved in a direction downward and inward, as seen from the liquid permeable coating layer 102. This implies that the sanitary napkin, along the side edges 109, 110, has rounded edges 125, 126 which, during the use of the sanitary napkin they have the purpose of being in contact with the wearer's body, in the reaches of the user's groin. The rounded ridges 125, 126 extend along the side edges 109, 110, along substantially the entire length of the sanitary napkin but are flattened to some extent at the leading edge 111 and the trailing edge 112, respectively . At ridges 125, 126 and protrusion 113, lower grooves 127, 128, extend where the menstrual exudate can be temporarily picked up if it is not immediately absorbed into absorbent body 104 '. In accordance with another embodiment not illustrated, the grooves may be deeper providing the rigid layer impervious to liquids 103 with groove. In such an embodiment, the longitudinal stiffness of the sanitary napkin is increased, and at the same time it becomes easier to compress the crotch portion. Accordingly, arms in the form of ridges and grooves increase rigidity in the direction of extension of the arms while on the other hand, rigidity in the perpendicular direction is reduced. The raised ridges 125, 126, along the side edges 109, 110 of the sanitary napkin, serve several functions. On the one hand they constitute reinforcing arms that increase the resistance to bending of the sanitary napkin when it is folded along substantially transverse bending lines, and on the other hand, the rounded surface facing the wearer contributes to an increased comfort for the user. In addition, the shape of the rigid coating, impervious to liquids, results in a certain degree of compressibility during use. Accordingly, the raised ridges and longitudinal edges of the central protrusion 113 serve as notches, whereby the crotch portion compression 108 can be performed in a controlled manner. During the use of the sanitary napkin, pressure forces of the user's thighs and groin have the effect that the side edges 109, 110 of the sanitary napkin are pressed inward in a direction toward the longitudinal center line 123. What happens next is that the raised crests 125, 126 are slightly curved inwards in a direction towards the protrusion 113. Accordingly, the crotch portion 108 of the sanitary napkin generally maintains the shape it has received in production, even when the width of the crotch portion is slightly reduced by compression. A particular advantage is that no additional unwanted wrinkle or any other undesired deformation of the crotch portion 108 is observed. When the liquid impervious coating layers, for example polyethylene plastic or polypropylene plastic with a thickness between about 0.5 and 1 mm are used, the crotch portion 108 formed has a high elasticity. Accordingly, the crotch portion 108 substantially regains its original shape and its original width such that compression is suspended. As in the case of the sanitary napkin illustrated in figures 1-3, however, it is essential that the crotch portion always have a guaranteed minimum width during use, to avoid any leakage. For this reason, the stiffness of the crotch portion must be sufficiently high so that it does not compress more than about 80% of its original width during normal conditions of use. In order to further increase comfort for the user, the front portion 106 is provided as a recess in the front edge 111. The recess is formed by the front edge 111 curved in a direction toward the crotch portion 108 of the sanitary towel. Since the front edge 108 has a concave curve, it adapts better to the profile of the venus mount of the user, so that the risk of rubbing is almost non-existent. Example 1: In order to estimate the edge stiffness of an absorbent article, that is, the elasticity of the article when it is subjected to compression in a transverse direction, the following test was carried out: The absorbent article was divided in two. halves along the longitudinal centerline, after which one of the halves was fixed between two footsteps mounted on an Instron voltage tester (1122, 4301, or 4464 with a 10 N cell), so that the cut edge of the article was directed down between the jaws and the intact lateral edge protruded freely from the jaws. After this, a metal rod with a cylinder mounted thereon was pressed perpendicularly against the edge in the region of the article which during use is arranged in the critical area of the wearer's crotch area. The force required to press down the edge was recorded by means of the voltage tester as a function of the distance pressed downwards. The cylinder that was used to press against the edge had a length of 40 mm and a diameter of 10 mm. When the metal rod is pressed against the edge of the article, an initial resistance arises. This is very different in the case of homogeneous rigid materials such as plastic or hard paper. In the case of thicker porous or fibrous materials, the edge is fractioned before bending or breaking. Two peaks of forces are recorded for these materials. An absorbent article such as a sanitary napkin, an incontinence protector or a pantyliner may have several rigid edges and therefore offer several strength peaks. The article, for example, may have a first welded edge joint, then a relatively soft and wide absorbent first core and then a harder and narrower absorbent core. Absorbent articles with a shell or stiffening element made of an elastic material such as a folded plastic layer do not offer a different strength peak; on the contrary, the printing force is almost proportional to the distance printed to the metal rod with the cylinder. For an absorbent article to have a sufficiently high resistance to transverse compression, it should not be possible under normal conditions to compress the crotch portion of the article plus a level that allows the width of the article to always be approximately 15 mm and preferably always about 20 mm. In addition, articles with widths that start larger than 40mm should be easily compressed by means of the action of the forces that arise during use, so that the width during use does not exceed approximately 40mm. It has been found that it was difficult to specify especially a force in which an absorbent article must present a permanence sufficiently. In order to estimate the magnitude of the force, it must be taken into account that the registered force varies according to the aforementioned factors, and also that it is difficult to predict with precision the action of the force to which the article will be subjected during the use . The measurements of edge rigidity performed, however, indicated that the force required to press the lateral edge of the article inwardly over a distance of 10mm should be greater than about 20N if an absorbent article is to be obtained in accordance with the present invention. that has a permanence enough. In the case of very rigid articles, for example, with elements of metal stiffness, a revision of the edge rigidity evidently no longer makes sense. Accordingly, the method is primarily suitable for determining whether an absorbent article has sufficient compressive strength. Materials such as paper or highly compressed fiber layers that break when compressed such that they later lose their ability to resist compression can not be used in articles in accordance with the present invention. Example 2: The intrinsic stiffness of numerous planar materials was determined by means of the Circular Bending Method ASTM D 4032-82, said method is described in detail in EP 0 336 578. The equipment consists of a rectangular plate having an opening circular, funnel shaped in the central part. The material is placed above the circular opening and is subjected to a force such that the material reaches the bottom of the plate. The force is measured and a value of the intrinsic rigidity of the material is provided. Materials having intrinsic stiffness suitable for the purpose of the present invention are materials for which a force of at least 100 N was recorded. The invention should not be considered as limited to the embodiments described herein, but numerous variations and modifications are conceivable within the scope of the claims. For example, the present invention comprises all types of absorbent articles that can be substantially accommodated in the groin area of a wearer. In addition, all conceivable combinations of the described embodiments are encompassed by the present invention.

Claims (11)

1. CLAIMS An absorbent article, such as a sanitary napkin, an incontinence protector, or a pantyliner, said article having a generally elongated shape with a longitudinal direction and a transverse direction and showing the lateral edges (9,10) , the end edges (11,12), two end portions (6,7), and a crotch portion (8) located between the end portions (6,7), said article further presents a permeable coating layer to liquids (2), intended to face the user during use, and a liquid impervious coating layer (3), provided to face the opposite side to the wearer during use, characterized in that the article less within the crotch portion (8) comprises a stiffening element (15) of a material with very high intrinsic rigidity so that the article within at least a portion of the crotch portion (8) constituting at least s 5 mm of the extension of the crotch portion (8) in the longitudinal direction, has an extension in the transverse direction, which during the use of the article is between 15mm and 40mm, and preferably between 20mm and 35mm. An absorbent article according to claim 1, characterized in that the stiffening element (15) can be compressed only up to 80% of its original width during compression of the crotch portion (8) in the transverse direction of the article with the forces that occur during use. An absorbent article according to claim 1, characterized in that the stiffening element (15) is profiled in the transverse direction of the article and shows at least one ridge (125, 126), or groove (127, 128), which extends in the longitudinal direction. An absorbent article according to claim 3, characterized in that a longitudinal ridge (125, 126) with a rounded surface is arranged along each lateral edge (109, 110) of the article at least in the crotch portion (108). ). An absorbent article according to claim 1 or according to claim 2, characterized in that the stiffening element (15) in the crotch portion (8) on both sides along the side edges (9,10). of the article is surrounded by soft, easily deformable edge portions (8). An absorbent article according to any of the preceding claims characterized in that a force of at least 20 N is required to press a side edge (9, 10) inwardly over a distance of 10 mm during compression perpendicular to the side edge (9). , 10). An absorbent article according to any of the preceding claims, characterized in that the material of the stiffening element (15) has an intrinsic stiffness exceeding 100 N, measured in accordance with ASTM D 4032-82. An absorbent article according to any of the preceding claims, wherein the end portions (6,7) are constituted by a front portion (6), and a rear portion (7), characterized in that the article, at least within the front portion (6) and the crotch portion (8) has a high resistance to bending against bending along transversely extending bending lines, whereby the front portion (6) and the crotch portion (8) of the article show a high stay of form during the use of the article, and also because the front portion (6) of the article is inclined in relation to the crotch portion (8) in a direction toward the liquid permeable surface (2), whereby the front portion (6) forms an alpha angle towards the crotch portion (8). 9. An absorbent article according to claim 8, characterized in that the article at least inside the front portion (6) and the crotch portion (8) has a high resistance to bending against bending along fold lines that they extend longitudinally. 10. An absorbent article according to any of the preceding claims, characterized in that the crotch portion (108) of the article has a transversely extending transverse line (124), where the side edges (109, 110) of the article change inclination in relation to the longitudinal centerline (123) of the article. article in the vicinity of the intersection point between the transverse line (124) and the lateral edges (109, 110), and from the transverse line (124), the width of the article increases in a direction towards the front edge ( 111), which exceeds the width of the crotch portion (108) in the transverse line (124), where the inclination of the side edges (109, 110) in the front portion (106) is defined by means of a beta angle between each respective side edge (109, 110) and a longitudinal line parallel to the line of centers (123), where beta lies within a range of 30 ° to 90 °. An absorbent article according to any of the preceding claims, characterized in that the liquid impermeable coating layer (103) of the article is constituted by a rigid plastic layer impermeable to liquids, whereby the impermeable coating layer to liquids (103) constitutes the rigidity member of the article.