MXPA99007459A - An absorbent article that includes a liquid barrier with improved sealing - Google Patents

Abstract

A method of improving in an oblong absorbent article that includes a liquid-impermeable bottom sheet, an upper liquid-permeable sheet and an absorbent body disposedbetween these sheets, and on each side of the longitudinal center line of the upper sheet at least one longitudinal elastic liquid barrier, the sealing effect afforded against the skin of the wearer by at least one liquid barrier on each side of said centre line by causing the absolute value of the negative product 2&ggr;cos&thgr;m/r in this liquid barrier to increase. A method of increasing in an absorbent article that includes an essentially liquid-impermeable top sheet above an absorbent body enclosed between an upper liquid-permeable sheet and a liquid-impermeable sheet, the top sheet being provided with elastic for shaping the article to the wearer's body and incorporating apertures intended to register with the anus and the urethra orifice of a wearer in use, around which apertures elastically puckered sealing edges are disposed, the absolute value of the negative product 2&ggr;cos&thgr;m/r for at least one sealing edge. An absorbent article where the absolute value of the product 2&ggr;cos&thgr;m/r for at least one liquid barrier on each side of the centre line of the absorbent body or for at least one sealing barrier lies above the line y=kx+m, where x designates the available elongation, k has the value -14/30 and m has the value 48 within the major part of an available elongation range of between 20 and 40%.

Description

AN ABSORBENT ITEM THAT INCLUDES A BARRIER TO THE LIQUIDS WITH IMPROVED HERMETIC CLOSURE. The present invention relates to absorbent articles, such as diapers, or incontinence guards, which provide a better hermetic effect against the wearer's skin than prior known articles of this type. The invention also relates to a method of ") producing such articles. An absorbent article of the type to which the invention relates will include a liquid impervious sheet which is intended to be remote from the wearer during use, an absorbent body, and a liquid pervious top sheet which is adjacent to the wearer during the use. When the absorbent article in question is a diaper or an incontinence guard, the article will also include flexible side flaps or wings extending to the sides projecting from the absorbent body on its two sides and elastic devices extending longitudinally along the length of the body. the free lateral edges of the lateral fins 20 at least within the part that is intended to form the crotch portion of the article during use, said fins and elastic devices permitting the absorbent article to conform to the wearer. Said elastic devices function as a leg elastic when the article is worn. Thus, when the article is worn, the elastic elements will stretch and hold the lateral fins tight against the user. The absorbent articles of today have a very high absorbency and can also retain liquid at 30 pressure. The biggest problems occur in the case of rapid discharges of liquid. In such cases, it is necessary for a large volume of liquid to first pass through the liquid permeable topsheet and then be absorbed by and dispersed in the absorbent body. This does not happen instantaneously. The time it takes for the liquid to pass through the upper sheet can be from about one to two minutes, during which time liquid will leak to the edges of the article and escape through them. These problems are faced with the help of the liquids or internal flips or side flaps that are intended to resist the escape of liquid in case of rapid discharges of liquid. The originally used turns were primarily intended to retain stool and were formed by bending a portion of the liquid pervious top sheet around an elastic yarn. In recent times, manufacturers have begun to produce the turns from a liquid impervious material so that it also retains liquid. When the leg elastic is stretched in the absorbent article and the article is held in the wearer, the elastic element of the barriers to liquids will also be stretched, thereby raising the barriers. The elastic element of the barriers will hold the barrier edges taut against the user. The vertical barriers to the liquids then form under the user a "channel" in which a large quantity of rapidly discharged urine can be accommodated for the time necessary for the liquid to pass through the liquid permeable topsheet. Attempts to improve the effectiveness of such liquid barriers have hitherto been directed to the use of denser materials and fins of sufficiently large size. However, one drawback is that the liquid will rise above the edge of the barriers and will escape when the volume of liquid discharged is excessive or when the user sits down or presses down the space between the vertical barriers to the liquids. Thus, current absorbent articles, such as diapers or incontinence guards, may include along the external longitudinal edges of the article tight edges that are intended to be tight around the wearer's thighs and adapt the article to the wearer's body, as well as a pair of turns or internal barriers to the liquids that are inwards of the external longitudinal edges and that are intended to form a waterproof barrier against the rapidly discharged liquid that is not immediately absorbed by the absorbent body of said article . Said internal turns will thus be able to withstand a relatively high liquid pressure for a limited period of time of the order of a minute or so. When this period of time ends, the liquid has been absorbed by the absorbent body. Also available are articles that include transverse turns that seal tightly the transverse edges of the absorbent body. Absorbent articles that lack the internal barriers to the liquids described above are also available. In such cases, the external longitudinal hermetic edges form the only barriers to the liquids of the absorbent body. Absorbent articles are also available that include a liquid impervious sheet which is intended to be adjacent to the wearer during use and which includes elastic threads to adapt the article to the wearer's body. Said liquid impervious sheet includes at least one hole that will be in correspondence with the anus and the urethral orifices of the user. Elastic is provided around at least a part of the circumference of the hole or holes to adapt the edges of the hole to the user and form a hermetic seal. Beneath the liquid impervious sheet is an absorbent body which is enclosed between a liquid-permeable sheet and a liquid-impervious sheet, such that the absorbent body hangs below the user, the sheet being impermeable to liquids away from him.

The internal turns are partly composed of a thin barrier sheet of inelastic material essentially impermeable to liquids, for example, non-woven, and partly of an elastic device which gathers the edge of the barrier a. the liquids that are against the user. The non-resilient and inelastic material is attached along a longitudinal edge to the liquid-permeable upper sheet of the absorbent article so that no liquid can pass between the two sheets, or to the lower sheet impervious to liquids along the length of the sheet. a lateral edge of the article. The elastic device is held along the other edge of the non-resilient material, so that it picks up the liquid barrier and forms a shirred edge with it, which will extend partially when the article is worn. The puckering of said edge is normally achieved with an elastic thread placed in a channel in the inelastic material, said channel being formed by folding and welding an edge of the material. When the absorbent article is worn, the gathered edge will stretch partially, the length of said stretch depending on the size of the wearer and how the article is worn. The barriers to the described liquids or the leg elastic can not be used in absorbent articles that are fastened against the wearer's body by means of special elastic pants or pantyhose. These absorbent articles may include other watertight edges that are not stretched and held taut against the body. Thus, EP-A1-0534 488 discloses gaskets that are preformed so as to protrude from the central part of an absorbent article, illustrated with a sanitary napkin in the description of the preferred embodiment. Seals can be formed by crimping a strip of material, such as non-woven material so that they form a flexible turn that rests against the wearer's body comfortably. In one embodiment, the seals are attached directly to the edges of the absorbent article, one edge being joined to the seal strip to the top sheet of the absorbent article and the other edge to the bottom sheet. The curling of the. The material forms cavities to impart flexibility and stability to the seals and the loops can also enclose elastic elements that are stressed when applied to the article to impart arched shape to the article. In another embodiment, the seal material is an elastic material that attaches to the longitudinal edges of the sanitary napkin. The material is subjected to tension when applied to the sanitary napkin. The purpose of doing so is to impart an arched form to the article. The sanitary napkin is placed in the crotch of a pantyhose during use and is pressed against the wearer by the force exerted by the panty. Thus, the force applied by the sanitary napkin against the user is indirectly produced by the pressure exerted by the panty. Embodiments with seal that include elastic elements do not produce force against the body of the user. The purpose of the elastic elements, if they are used, is to impart an arched shape. This differs from the diaper or incontinence guard according to the invention with a barrier element including an elastic device, where the barrier element will stretch against the user during use and will thereby create a barrier to liquids with a good hermetic effect. The body of the user is the one that causes the elastic device present in the bar to be tensioned. The object of the present invention is to provide a method of improving the capacity of an absorbent article that includes elastic leg, to remain tight against the user, with the help of several measures. Another object of the invention is to provide an absorbent article that includes elastic leg and has better hermetic properties with respect to the user of the article. The invention will now be described with reference to the accompanying drawings, in which: Figures a, b illustrate measuring equipment used to determine the exhaust pressure or penetration pressure for an elastic barrier material. The figure represents the equipment without applied material, figure lb represents the equipment with material applied in stretched state, respectively, and the figure is a principle illustration of how the exhaust pressure can be determined. Figures 2a, b schematically illustrate a pore in a liquid barrier and the principle of determination of the weighted average value eos? M and determine the radius r. Figure 3a illustrates a conventional diaper or incontinence protector with vertical barriers to liquids. Figures 3b, c are enlarged views of the principle of a section through region B of figure 3a, first with respect to a conventional diaper (3b) and secondly for an embodiment of the invention (3c). Figures 4a, b illustrate the principle of calculating the available elongation or stretch. Figure 5a is a graphic illustration representing the measured penetration pressures for three different barriers to liquids. Figure 5b is a comparison diagram illustrating calculated penetration pressures and measures for the best barrier to the liquids of Figure 5a, at the different available elongation angles. Figure 5c is a diagrammatic illustration of the lower penetration pressures for barriers to liquids constructed according to the invention. Figure 6a is a graphical illustration of the measured penetration pressures for a liquid barrier, vertical and conventional, on the one hand, and for two embodiments of the invention, on the other. Figure 6b is a comparison diagram illustrating the penetration pressures calculated and measured at the different elongations available for one of the embodiments of the invention shown in Figure 6a.

Figure 7 illustrates the penetration pressures measured for a conventional vertical barrier to liquids, on the one hand, and for another embodiment of the invention, on the other. Figures 8-14 are reproductions of photographs taken with an electron microscope of different barriers to liquids at different available elongations. And Figures 8a-12a are views corresponding to the photographic reproductions of Figures 8-12. An absorbent article, such as a diaper, is made to be used by people of different sizes. This is achieved by collecting or pursing the barriers to liquids and side edges with the help of elastic. Said barriers to liquids and side edges will stretch to a different degree according to the size of the user, and the tension around the edge of the barrier will therefore vary according to the size of the user. It is to be expected that the stress in the barrier elastic is important in the studies on the sealing property of a liquid barrier and, consequently, the degree of stretch of the barrier will also be important. A considerably stretched barrier will exert considerable tension against the user's skin and can be expected to provide a better seal than corresponding barriers that stretch to a lesser degree. A desire in this regard has been to produce as much tension as possible in the liquid barrier and thereby obtain the best possible hermetic effect. However, it is not possible to use elastic in which the tension is excessively high, because the absorbent article will then be uncomfortable to arrive and leave marks on the skin. The term "available elongation or stretch" can be used when considering the degree to which a liquid barrier is stretched. In the manufacture of the absorbent article, for example, a diaper, the elastic material, which has a given degree of stretchability, is firmly "fixed" to the remaining non-stretchable material, normally non-woven. When the article is being used, the degree to which the elastic material stretches in the manufacture of the article can not be overcome, because the elastic material is firmly fixed to a non-stretchable material. This is shown in Figure 4a. The elastic material has the length L at this point. The non-stretchable material to which the elastic material is attached, is somewhat gathered when the diaper is placed on the wearer's body. The elastic material has then contracted to the shorter length Lx. The available stretch or elongation X is the extent to which the material can be stretched from the state of use to the state of maximum stretch of the product. This can be expressed with the formula: L = Lx ((X / 100) + - 1), where X is the stretch or percent elongation available. Test equipment was constructed with the intention of studying the hermetic effect achieved between a barrier to liquids or some other shirred barrier and the skin of the user. Said equipment is represented in FIGS. 1, 1 and 1 and includes a Plexiglas support that includes a base plate a and a vertical support plate b. A first semicylindrical element, open upwards 1 is fixed horizontally to the vertical support plate b and has around its periphery a scale indicating the stretch or elongation available. One end of the semicylindrical element is attached to the support plate, while the ot_5? end has an end wall 1 '. In the lower part of the semicylindrical element 1, a hole 2 is provided, to which a vertical filling tube 3 and an inclined measuring tube 4 lead, both tubes having a scale expressed in mm of water. The equipment also includes a second loose semicylindrical element 5 whose diameter is somewhat larger than the diameter of the first semicylindrical element 1 and which has an open side and an end wall 5 'at its other end. As shown in Fig. Lb, the measurement operation is performed by fixing a barrier to the liquids around the outer periphery of the first semicylindrical element and fixing said barrier around the upper edges. The elastic part 7 is directed towards the connection of the semicylindrical element with the support plate b, and the liquid barrier material is folded around the end wall 1 'of the first semicylindrical element 1 on the other side. The elastic part is fixed along the scale in the semi-cylindrical element so that the stretch or elongation available can be read. The end wall 5 'of the second semicylindrical element 5 is placed against the end wall 1' of the first semicylindrical element, placing said bent part upwards of said barrier material in between and pressed therewith with the help of a clamp 10, to obtain a small free space 9 between the cylindrical walls. Synthetic urine is introduced through the vertical tube 3, the barrier to the liquids is first lowered to fill the free space between the semi-cylindrical elements. Then liquid pressure builds up against the elastic edge 7 at the same time as a column of liquid is formed in the tubes 3, 4, where the pressure can be read. Liquid is introduced until there is leakage in arrow B (figure le) at the penetration pressure. Three types of liquid barriers, Hug-gies vertical shirring, Pampers vertical shirring and Peaudouce leg elastic were studied, measuring the tendency for escapes with the elastic element stretched and fixed to different extensions available. The pressure of liquid at which leakage will occur with respect to a barrier stretched to a given extent, ie, a barrier having a given elongation or stretch available, was determined with the aid of the test equipment, it being found that said pressure varied depending of the extension in which the pursed edge is stretched. The measured values are represented in the diagram of figure 5a. However, as will be evident from the figure, different barriers give different penetration pressures at the same stretch or elongation available. It seems therefore that the hermetic effect is influenced by other factors besides the tension of the elastic material only. The invention is based on an attempt to provide for an improved hermetic effect based on factors other than the actual tension of the elastic. Based on the theory that exhaust does not occur merely because the elastic present in the barrier material ceases to contact the user's skin, but rather is produced primarily through the penetration pores or channels that form between the The skin of the user and the folds of the rim of the barrier material, efforts have been made to create a model from which the exhaust pressure can be determined theoretically and therefore know the parameters in which it should be influenced to achieve a better Hermetic effect. The capillary pressure of the pores in porous structures can be calculated with the Laplace equation. According to Laplace, the capillary pressure? P = 2? cos? / r, where? Is the surface tension of the liquid,? is the angle of wetting of the liguid to the material in the capillary walls, and r is the radius of the capillary. When ? is greater than 90 °, cos? is negative and? P is also consequently negative. The capillary wall is hydrophobic and it can be stated that the resulting pressure? P describes the penetration pressure, that is, the maximum pressure that a capillary or pore can withstand. When ? is less than 90 °, the capillary wall is hydrophilic and? P and cos? They are positive. Then liquid is "sucked" into the pores. When studying the pressure in a capillary or pore, where the wall consists of several materials, such as in a pore formed between the skin and a fold in a barrier to the liguids, the circumference ratio of each material must be weighted to obtain a value half of cos? , which henceforth is called cos? m. The penetration pressure will then be? P = 2? cos? m / r. In the present case, the walls of the pores consist in part of a hydrophilic material, i.e., the skin, which has a wetting angle of less than 90 °., and in part of the hydrophobic material of the liquid barrier, which has a wetting angle greater than 90 °. Cos? M is the weighted average value of cos? of the walls of the pores and calculated as illustrated in Figure 2a, where A designates the hydrophobic wall of the circumferential proportion and B designates the hydrophilic wall of the circumferential proportion, where A + B = 1. Cos? m will be it is equal to A-cos? fob + B-cos? fU. As described below, tests have been carried out with the intention of verifying whether the described model can be used or not as a basis with which the penetration pressure can be evaluated. The angle of wetting of the skin varies according to the state of the skin, that is, if the skin is clean or dirty, for example. A measuring compound composed of Plexiglas was used with a wetting angle of 77 °, which is close to the average value of the wetting angle of the skin (approximately 74 °), for comparison purposes. The measurement was carried out on the commercial liquid barrier which produced the best hermetic result according to Figure 5a, ie the Huggies vertical shirr having a wetting angle of 120 °. The liquid used was synthetic urine,? is the surface tension of synthetic urine, that is, 0.06 N / m. The contact of a liquid barrier with the measuring equipment was studied at different elongations available with an electron microscope, 130 magnifications, as illustrated in Figures 8-12 and 8a-12a. As will be apparent from the figures, a penetration pore is formed between the wires or fibers of the barrier material and the Plexiglas wall of the test equipment. It is assumed that said pore functions as a capillary, where r = the radius of the largest possible circle that can be enclosed in the channel, as is evident from Figure 2b. The penetration pore is shown in Figures 8a-12a. The following pore radius values were obtained at the different elongations available, as shown in the figures.

Elongated elongation Radius of the pores 10% 0.0208 mm 20% 0.0812 mm 30% 0.1208 mm 40% 0.1458 mm 50% 0.1458 mm Comments: It was difficult to measure the radius of the pores in the photograph at an available elongation of 10%, and therefore the value given may not be reliable. The crosses marked in Figures 8a-12a represent the lateral endpoints of the pore for calculating the proportions of the hydrophobic and hydrophilic length of the pore. The length relationship between hydrophobic and hydrophilic surfaces in the pore at different available elongations is shown in the following Table.

Calculations related to "Huggies vertical shirring" versus Plexiglas: Elongation available at 10%? P = 2- 0.06- (0.39- cos74 ° + 0.61- cosl20 °) /0.0208- 10 ~ 3? P = -1139 Pa = > the absolute value of the penetration pressure = 114 mm H20.

Elongation available at 20%? P = 2- 0.06- (0.39- cos74 ° + 0.61- cosl20 °) / 0, 0812 • 10"3? P = -291.9 Pa => the value absolute of the penetration pressure = 29.2 mm H20.

Elongation available at 30%? P = 2- 0.06- (0.32- cos74 ° + 0.68- cosl20 °) / 0, 1208 • 10"3? P = -250.1 Pa => the value Absolute pressure of penetration = 25.0 mm H20.

Elongation available at 40%? P = 2-6.6- (0.39- cos74 ° + 0.61- cosl20 °) / 0, 1458- 10 ~ 3? P = -162.6 Pa = > the absolute value of the penetration pressure = 16.3 mm H20.

Elongation available at 50%? P = 2- 0.06- (0.5- cos74 ° + Q, 5- cosl20 °) / 0, 1458 • 10"3? P = -92.3 Pa => the value absolute penetration pressure = 9.2 mm H20.

Figure 5b represents the comparison between the penetration pressures measured with the test equipment and the penetration pressures calculated with the previous formula. Since the calculated and measured penetration pressures agree well, it is therefore possible to improve the hermetic effect of the liquid barrier in an absorbent article against the skin of the user by influencing || P |, that is, | (2? Cos? M / r) | of the barrier so that this value increases. One measure in this regard is that the tension of the elastic is sufficiently high to prevent the liquid barrier from leaking liquid at a lower pressure as a result of the elastic relaxation and letting the barrier "loosen" from the user by virtue of the a column of liquid that pushes the barrier downwards so that it stops contacting the contact surface. It can be done that | ? P | increase by increasing the product | (2y cos? M / r) | . The invention thus relates to a method of improving the hermetic capacity of an absorbent article by increasing the product - (2? Cos? M / r) of one or more barriers to the liquids of the article. The product can be increased, for example: 1) Influencing the wetting angle between the liquid to be sucked and the skin or barrier material, respectively; 2) Influencing the radius of the pores, that is, the capillary radius, formed between the barrier material and the skin; and 3) Influencing both the wetting angle and the radius of the pores. Since the intended effect is to increase the absolute value of product 2? cos? m / r, it is not necessary to increase unilaterally | cos? | or decrease r. It is possible that a procedure to increase | cos? m / r) | it also implies the simultaneous increase of the radius. Provided that the increase of | cos? m / r) | be proportionally greater than the increase in radius, an improved result will be obtained despite the increase in radius. Likewise, a procedure that decreases the radius may result in a decrease of | cos? M |. However, an improved result will still be achieved provided that the latter decrease is proportionally less than the decrease in radius. The invention also relates to an absorbent article such as a diaper or incontinence protector having improved hermetic properties against the wearer and which has been produced so that, in the case of at least one pair of liquid barriers of the Article, the absolute value of product 2? cos? m / r will be greater than that obtained by using the above known absorbent articles. More specifically, during most of the available elongation or stretch range of 20-40%, preferably for most of the range between 15-50%, and in particular for most of the range between the available elongation of 10 and 80 %, the absolute value and of product 2? cos? m / r will be above the line y = kx + m, where x denotes the stretch or elongation available, k has the value -14/30 and m has the value 48 (line 1), preferably 51 (line 2) , more preferably 57 (line 3) and even more preferably 63 (line 4) and in particular 69 (line 5). These lines are represented in FIG. 5c, in which the measured penetration pressure of the very effective liquid barrier currently known, ie the vertical shirring barrier of Huggies, has been represented by way of comparison. The invention will now be described in more detail with reference to particular exemplary embodiments, as well as with reference to the accompanying drawings. EXAMPLES Figure 3a depicts a conventional diaper or incontinence guard 20 including a liquid permeable topsheet 22, an absorbent sheet 23, and a liquid impermeable bottom sheet 21, said sheets being delimited by two transverse edges 24, 25 and two longitudinal edges 26, 27. The illustrated article also includes leg elastic 28 which extends longitudinally and a vertical barrier to liquids 29 on each side of the central longitudinal line. Figure 3b is a sectional view illustrating the construction of the vertical liquid barrier including a liquid impervious sheet 12 whose free edge is curved around two stretched elastic threads 13. The threads 13 serve to gather the sheet 12 Figure 3c illustrates an embodiment of the invention in which the pore radius has been reduced considerably, and it is constant and small already at high stretch or elongation available. In this case, the elastic threads 13 have been replaced by an elastic film 14. Said film will be essentially smooth against the skin. The pore radius approaches 0 already at high available elongation. Fig. 14 is a reproduction of an electron microscope photograph of an embodiment of the invention similar to the embodiment of Fig. 3c, in which an elastic film is used as the edge located in the liquid barrier, stretched against the Plexiglas . The small visible pores are the result of the film being a three-fold film in the illustrated case, where only the central layer is elastic. The outer layers used to bond the film to the barrier will crack when the core layer is stretched, as shown in Figure 15. Small visible pores, having a radius of about 0.02 mm, will remain essentially constant regardless of the algae available, because the height of the pores is constant even if the length changes. The upper curve of Figure 7 illustrates measurements made with said liquid barrier. The lower curve represents the results obtained with a Huggies vertical shirm. The wetting angle was changed in two tests. In the first case, a plastic film with a wetting angle of 97.5 ° was stretched over the first semi-cylindrical Plexiglas surface. This corresponds to a treatment of the barrier in such a way that the skin of the user obtains a greater angle of wetting. This is hydrophobic as opposed to the average skin wetting angle of about 74 °. The result of this change in the wetting angle (central curve) is compared in Figure 6a with the hermetic effect achieved with the vertical barrier to Huggies vertical shirring liquids (bottom curve). As shown by the measurement values, in this way an improved hermetic effect is achieved. The upper curve of figure 6a represents measurements obtained with a liquid barrier treated with petrolatum. Vaseline has a wetting angle of 100 °. Vaseline partially blocks the pores, that is, reduces the radius of the pores, and also smears the user's skin, thereby increasing the wetting angle of the liquid to the skin. As will be evident from the diagram shown in FIG. 6a, a considerable improvement is obtained which is greater than the improvement achieved when only the angle of wetting of the skin is changed, in spite of obtaining, at the same time, a reduction in the angle of the skin. dampening of the barrier by virtue of which the vaseline also smears the barrier to liquids and therefore decreases its wetting angle from 120 ° to 100 °. Figure 6b is a diagram showing the calculated and measured hermetic effects obtained by changing the wetting angle. The measured values were obtained by covering the Plexiglas with the plastic film described above, and correspond to the central curve of the diagram shown in Figure 6a. A good match is obtained between the calculated and measured values.

As will be apparent from the foregoing, the hermetic effect provided by an absorbent article can be improved by treating at least one of its liquid barriers in such a way that the absolute value of the negative product 2? cos? m / r is increased at least within the greater part of an available elongation band of 20-40%. The hermetic effect of an article that has a barrier to liquids where the absolute value of the negative product 2? cos? m / r is above the line y = kx + m at least within the greater part of an available elongation band of 20-40%, where x denotes the stretch or elongation available, k has the value -14/30 and m has the value 48, preferably 51, more preferably 57 and even more preferably 63 and in particular 69, will be substantially better than the hermetic effect achieved with conventional articles of this nature. The invention also relates to articles having transverse barriers to liquids, and to a method of treating such barriers to liquids in an identical manner to that described with respect to barriers to longitudinally extending liquids. Barriers to longitudinally extending liquids can be composed of leg elastic and internal turns. It will be understood that the invention is not limited to its exemplary embodiments described and that it includes all conceivable embodiments that fall within the scope of the following claims.

Claims (14)

1. A method for obtaining, in an absorbent article such as a diaper or an incontinence protector that includes: an absorbent body (23) placed between a lower sheet impervious to liquids (21) that is proposed to be away from the user during the use, a liquid-permeable top sheet (22) that is proposed to be next to the user, and any of the following: 1) at least one liquid barrier extending in the longitudinal direction (28, 29) on each side of the central line of the upper sheet, made of material practically impermeable to liquids (12) and fastened along or adjacent to a respective lateral, longitudinal end of the article and comprising an elastic, free watertight edge proposed to stretch against the user , or 2) on the upper sheet (22), a liquid-proof upper sheet that is proposed to be against the wearer, includes elastic to shape the article with the body of the u suture, and includes proposed openings to coincide with the anus and orifice of the user's urethra, around whose openings elastically folded hermetic edges, are placed on the upper sheet, an improved hermetic ability against the skin of a proposed user, with a determined elongation available, by at least one air-tight edge (28, 29) on each side of the center line, is characterized by the modification or treatment of the absorbent article in such a way as to cause the absolute value of? P = 2 to increase ? cos? m / r for the airtight edge (28, 29), where? designates the surface tension of the liquid to be absorbed by suction, r designates the radius of the largest circle that can be surrounded in any pore formed by the hermetic edge against the skin of the user in the determined elongation determined, and cos? m is the weighted average value of cos ?, where? is the angle of wetting of the liquid to the material in the pore walls, taking into account the different materials in the walls of this larger pore.

2. The method according to claim 1, characterized by the increase in the absolute value of P when at least in most of an available elongation range of 20-40%.

3. The method according to claim 1 or 2, characterized by the increase in the absolute value of? P at least 5%, particularly at least 15%, preferably at least 25% and then particularly at least 35%.

4. The method according to any of the preceding claims, characterized by causing the pore radius of the hermetic edge to decrease at least at an available elongation above 60%, particularly at an available elongation greater than 50%, more particularly at an available elongation greater than 40% and then preferably at an available elongation above 20%.

5. The method according to any of the preceding claims, is characterized by causing the absolute value of cos?

6. The method according to claim 5, characterized by treating the airtight edge so that a higher wetting angle of the liquid is obtained to the barrier material and / or so that a higher wetting angle of the liquid to the skin of the user will be obtained within these regions in which the airtight edge is against the skin when the absorbent article is worn.

7. The method according to any of the preceding claims, characterized by providing the hermetic edge with a layer of material that increases the absolute value of cos? M and / or that reduces r when the article is used.

8. The method according to any of claims 1-7 is characterized by increasing the absolute value of cos? M / r.

9. An absorbent article that includes an absorbent body (23) positioned between a lower sheet impervious to liquids (21) that is proposed to be away from the user during use, a liquid permeable top layer (22) which is proposed to be next to the wearer, and any of the following: 1) at least one longitudinal liquid barrier (28, 29) on each side of the center line of the upper sheet, made of material practically impermeable to liquids (12) and fastened along or adjacent to a respective longitudinal side end of the article and comprises a free elastic hermetic edge intended to stretch against the user during use, or 2) on the upper sheet (22) a liquid-impermeable upper sheet which is proposed to be against the wearer, includes elastic to shape the article with the user's body, and includes holes proposed to coincide with the anus and the hole of the The user's urethra, around which elastically folded hermetic edges are disposed in the upper sheet, is characterized in that with respect to at least one airtight edge (28, 29) on each side of the edge central line of the absorbent body, the absolute value of? P = 2? cos? m / r lies above the line y = kx + m, where x denotes the available elongation, k has the value -14/30 and has the value 48, particularly 51, preferably 57, more preferably 63 and , in particular 69, within the main part of an available elongation range of between 20 and 40%, and where? designates the surface tension of the liquid to be absorbed, r designates the radius of the largest circle that can be enclosed in any pore formed by the hermetic edge against the wearer's skin at a given available elongation, and cos? m is the value weighted average of cos ?, where? it is the wetting angle of the liquid to the material in the walls of the pores taking into account the different materials in the walls of the larger pore.

10. The article according to claim 9, characterized in that the free watertight edge includes a layer of a material in which a greater wetting angle of the liquid will be obtained to the edge material and / or from which a wetting angle will be obtained. of the liquid to the user's skin within these regions in which the airtight edge is against the skin and where the material is smeared to the skin when the article is worn.

11. The article according to claim 9 or 10, characterized in that the free hermetic edge is provided with a layer of material that at least partially fills the pores of the edge when the article is worn.

12. The article according to any of claims 9-11, characterized in that when the article is worn, the free hermetic edge has a pore radius that is practically independent of the stretch or elongation available and that is not more than 0.10 mm , preferably not greater than 0.08 mm, and more preferably not greater than 0.04 mm.

13. The article according to any of claims 9-12, characterized in that the free hermetic edge is composed of an elastic film in ribbon form.

14. The article according to any of claims 9-13, characterized in that the absolute value of? P = 2? cos? m / r is above the line y = kx + m within the greater part of an available stretch range of 15-50%, preferably within the greater part of the range of 10-60%.