MXPA04005340A

MXPA04005340A - Absorbent structure, and absorbent article containing the absorbent structure.

Info

Publication number: MXPA04005340A
Application number: MXPA04005340A
Authority: MX
Inventors: Guidotti Ted
Original assignee: Sca Hygiene Prod Ab
Priority date: 2001-12-21
Filing date: 2002-12-10
Publication date: 2004-09-27
Also published as: AU2002367164A1; JP2005512732A; WO2003055431A1; EP1463477A1; SE0104358D0; PL370272A1

Abstract

The invention relates to an absorbent structure (3) for an absorbent article such as a diaper (100), an incontinence pad, a sanitary towel or the like, the absorbent structure (3) having, in the longitudinal direction, a central portion (11) and two end portions (12, 13). The invention is characterized mainly in that the average density of the material in the central portion (11), at least in the dry state, is higher than the average density of the material in the end portions (12, 13) and in that the central portion (11), at least in the dry state, has a lower basis weight than the end portions (12, 13), the density and the basis weight being calculated on the basis of the entire surface area of the central portion (11) or as appropriate the entire surface area of the end portion (12, 13). The invention also relates to an absorbent article comprising such an absorbent structure (3).

Description

ABSORBENT STRUCTURE AND ABSORBENT ARTICLE CONTAINING ABSORBENT STRUCTURE TECHNICAL FIELD The present invention relates to an absorbent structure for an absorbent article such as a diaper, an incontinence pad, a sanitary napkin or the like, the absorbent structure having, in the longitudinal direction, a central portion and two end portions. The invention also relates to an absorbent article containing said absorbent structure.

PREVIOUS TECHNIQUE Absorbent structures for disposable absorbent articles such as diapers, incontinence pads and sanitary napkins are constructed in most cases from one or more layers of hydrophilic fibers, for example pulp from cellulose fluff pulp. In most cases, they also include superabsorbents, which are polymers that are capable of absorbing liquid that corresponds to many times their own weight. The absorbent structure may also comprise additional component parts, for example, to improve the liquid distribution or to increase the cohesive capacity and the ability to resist deformation under load.

A major problem, especially in the use of baby diapers and incontinence pads for adults, is that they have to be able to receive and absorb large amounts of fluid in a relatively short time, it is often these have spills before that the total absorption capacity has been fully utilized. Since a large amount of liquid can be discharged in a few seconds, this may lead to the absorbent structure temporarily being locally locally with the liquid in what is known as the liquid receiving zone. There is not enough time for the liquid to be distributed to other parts of the absorbent structure, which in turn can lead to fluid spillage outside the diaper. From EP 0,254,476 and EP 0,325,416, uni is known. Absorbent structure, which, in an area that is in essence directly in front of the wetting area, has a lower base weight and a lower density compared to the surrounding portions of the absorbent structure. By virtue of said structure, an area with an open structure and a large liquid admission capacity is obtained. However, it can be difficult for the liquid to be distributed from the high volume open structure in the wetting area to the two extreme portions. From EP 0,525,778, an absorbent structure is also known, which, in an area which is essentially directly in front of the wetting area, has a high basis weight and a lower density than the end portions. One advantage of such a structure is that the wetting area has an open structure of volume that is capable of rapidly receiving a greater amount of liquid. However, it has been found that there is opportunity for improvement with respect to the construction of an absorbent structure that is capable of rapidly receiving a large amount of liquid at the same time as being thin, flexible and discrete for use.

DESCRIPTION OF THE INVENTION By means of the present invention, an absorbent structure for an absorbent article of the type mentioned in the introduction has been produced, which structure is capable of quickly receiving a large amount of liquid while being thin, flexible and discrete for use. An absorbent structure according to the invention is characterized mainly in that the average density of the material in the central portion, at least in the dry state, is higher than the average density of the material in the end portions, and in that the central portion , at least in the dry state, has a lower basis weight than the end portions, the density and the basis weight that are calculated based on the total surface area of the central portion or as appropriate the total surface area of the extreme portions.

Since the central portion constitutes the area of the article that first receives the discharge of the liquid, it is important that this area can quickly receive a large amount of liquid. In addition, the central portion is subjected to relatively greater mechanical stress than the end portions during the use of the absorbent article.

This means that it is especially important for a thin, soft and flexible material that is placed in the central portion of the absorbent structure. An absorbent article comprising an absorbent structure according to the invention satisfies all those criteria. The central portion means that the absorbent structure area that is located in what is known as the liquid reception zone, ie in the area that is expected to be first moistened by the liquid discharged when the absorbent structure is used in the article. absorbent. The liquid reception area is usually positioned between 10 cm and 20 cm from the front edge of the absorbent structure. According to one embodiment, the absorbent structure comprises a liquid storage layer and a liquid receiving layer, the liquid receiving layer which is positioned at least in the central portion of the absorbent structure. The upper liquid receiving layer is preferably of such a size that it rapidly expands in the thickness direction of the structure upon wetting. An advantage of a liquid receiving layer that expands in the direction of thickness of the structure to wetting is such that a layer is thin before wetting and rapidly expands in the direction of thickness to wetting. This means that a structure becomes more open and bulky and can receive a large amount of liquid in less time. It is also possible to have a liquid receiving layer having a very narrow central portion before wetting but which, upon wetting, expands in the direction of its plane so as to increase its thickness. Upon wetting) the liquid receiving layer may therefore expand both in the thickness direction of the structure and in the direction of its plane, or, alternatively only in one of said directions. An example of a material for the liquid receiving layer is a superabsorbent foam. Said superabsorbent foam preferably has a density in the dry state from 0.2 g / cm3 to 10 g / cm3, and a basis weight in the dry state from 200 to 800 g / m2. An advantage of the superabsorbent foam is that it is a soft and flexible material. When a user moves, the article is subjected to the greatest mechanical stress in the crotch portion of the article, which means that it is especially advantageous for a soft and flexible material to be placed in the central portion of the absorbent structure. Another advantage of a superabsorbent foam as a liquid receiving layer is that said material is also capable of absorbing and storing liquid, which reduces the risk of liquid spillage. The perabsorbent foam is preferably highly compressed in the density in the dry state from 0.1 g / cm3 to 0.7 g / cm3 and a basis weight in the dry state from 200 g / m2 to 1500 g / m2. The superabsorbent material may be in the form of, for example, particles, flakes or fibers. However, a liquid storage layer consisting only of a superabsorbent material, for example, a superabsorbent foam, is also conceivable. According to another embodiment, the absorbent structure also comprises a liquid distribution layer. The liquid distribution layer consists of a thin layer which is positioned beyond the side which, when the absorbent structure is placed in the absorbent article, is intended to confront the user. The liquid distribution layer consists of a material with a good liquid distribution capacity, for example a thin layer of chemically produced cellulose fluff fibers. The chemically produced cellulose fluff pulps, which consist of essentially pure fibers of essentially pure cellulose, generally have a good liquid distribution capacity. In order to obtain a good liquid distribution capacity, such as a liquid distribution layer consisting of a structure with fine capillaries, and a layer preferably having a high density. If appropriate, said liquid distribution layer based on cellulose also contains a small amount of superabsorbent material in the form of, for example, particles. An advantage of a liquid distribution layer is that said layer is capable of distributing the liquid coming from the liquid receiving layer in the central portion by means of the liquid distribution layer outside the two end portions where the Liquid can accumulate and be stored in the liquid storage layer. Another suitable material for the liquid distribution layer is a thin layer of HIPE foam (high internal phase emulsion). Said foam is produced through the polymerization of a water-in-oil emulsion. The solid phase of the foam creates a capillary system. The invention also relates to an absorbent article such as a diaper, an incontinence pad, a sanitary napkin or the like having an essentially oblong shape, the article comprising a liquid permeable surface layer, a liquid impermeable back layer and , enclosed between those layers, an absorbent structure according to any one of the described modalities.

BRIEF DESCRIPTION OF THE FIGURES The invention will now be described in greater detail with reference to the illustrative embodiments shown in the accompanying drawings, in which Figure 1 shows a diaper seen from the side intended to confront the user during use; Figure 2 shows the absorbent structure in the diaper according to Figure 1 from the side intended to confront the wearer during use; Figure 3 shows a section through the absorbent structure along the line III-III in Figure 2; Figure 4 shows an alternative absorbent structure seen from the side intended to confront the user during use, and Figure 5 shows a section through the absorbent structure along the line V-V in Figure 4.

DETAILED DESCRIPTION OF THE FIGURES The diaper 100 shown in FIG. 1 comprises a liquid-permeable layer 1, for example made of non-woven fabric or perforated plastic film, a liquid-tight back layer 2, for example made of plastic film or non-woven fabric. woven hydrophobic and an absorbent structure 3 enclosed between the two layers 1 and 2. The diaper 100 is intended to surround the lower part of the abdomen of a wearer as a pair of absorbent briefs. It has a rear portion 4 intended to face backwards in the user during use of the diaper, a front portion 5 intended to face forward of the user during use, and located between the rear portion 4 and the front portion 5, a portion of crotch narrower 6 which is intended to be placed in the crotch of the user between the legs of the latter. In order that it is possible for the diaper to be fastened to form the desired underpants shape, tape flaps 7 are positioned near the rear waist edge 8 of the diaper. During use, the tape flaps 7 are attached to the outside at the front portion 5 of the diaper, close to the front waist edge 9, the diaper which is then held together around the wearer's waist. Of course, other fastening means are also possible, such as contact and closure tape, hooks or the like. The diaper 100 according to Figure 1 also comprises pretensioned elastic elements 10 which may consist of suitable material, such as an elastic foam, elastic bands or yarns covered with yarn. For purposes of simplicity, those elements have been shown in the extended state in Figure 1. However, as soon as the stretching ceases, the elastic elements contract and thus form elastic leg bands of the diaper. The diaper 100 also comprises an absorbent structure 3. The absorbent structure 3 has a central portion 11 placed in the crotch portion 6 of the diaper and two end portions 12, 13 placed on the front portion 5 and, respectively, the back portion 4 of the diaper and shown in detail and alternative embodiments in Figures 2-5. Alternatively, the liquid impermeable surface layer 1 may be a part of the absorbent structure 3. An advantage of such construction is that, when the absorbent structure 3 comprises material that is highly compressed in the dry but rapidly expanding state upon wetting, the absorbent structure 3 can absorb freely without being exposed to the risk that the gap between the liquid-tight backing layer 2 and the liquid-impervious surface material 1 can be very small. Figure 2 shows the absorbent structure 3 in the diaper 100 according to Figure 1 from the side intended to confront the wearer during use. The absorbent structure 3 has a central portion 11, a first end portion 12 and a second end portion 13. The absorbent structure also has a front end edge 18 and a rear end edge 19. The central portion 11 represents an area in the absorbent structure which is located in what is known as the liquid reception area 14, i.e. the area that is expected to be first moistened by the discharged liquid when the absorbent structure 3 is used in an absorbent article. The liquid reception area is usually between 10 cm and 20 cm from the front edge 18 of the absorbent structure 3. The absorbent structure 3 is further constructed from three different layers, a liquid receiving layer 15, a liquid storage layer 16 and a liquid distribution layer 17. The liquid receiving layer 15 is placed in the central portion 11 of the absorbent structure and is intended to be located near the liquid impermeable surface layer 1 when it is used in an absorbent article. The liquid receiving layer 15 is made from, for example, a superabsorbent foam which is highly compressed in the dry state but which rapidly expands in the thickness direction of the liquid receiving layer 15 in contact with the urine . The liquid receiving layer 15 can also be a foam based on cellulose. An example of a cellulose-based foam is a compressed foam made of regenerated cellulose, which is known as a viscous foam. Upon wetting, said compressed viscous foam expands very rapidly in the thickness direction of the material. It is also possible for the liquid receiving layer to have a very narrow central portion before moistening, but the layer, upon wetting, expands in the direction of its plane so as to increase its width. Upon wetting, the liquid receiving layer 15 can therefore expand both in the thickness direction of the structure and in the direction of its plane or, alternatively, only in one of said directions. In addition, the liquid receiving layer 15 may be a dry formed sheet containing 5-100% cellulose fibers, which have a density from 0.2 to 1.0 g / cm3 and a basis weight from 30 to 1200 g / m2 , whose sheet has been formed by means of compression of a web containing cellulose fibers without defibering or subsequent lint formation.

The liquid storage layer 16 is placed in the end portions 12, 13 e3 the absorbent structure 3. The liquid storage layer 16 in the absorbent structure 3 in Figure 2 consists of two separate units, a liquid storage unit which it is located in the first end portion 12 and the other liquid storage unit which is located in the second end portion 13. The liquid storage layer 16 contains in a conventional manner superabsorbent material, ie material that is capable of absorbing liquid that it often corresponds to its own weight, and whose material is also capable of retaining liquid under external load. The liquid storage layer is preferably a mixed structure made of cellulose fluff fibers and superabsorbent material. The mixed structure consists of cellulose fluff fibers and a superabsorbent material which preferably has a density in the dry state from 0.1 g / cm3 to 0.7 g / cm3 and a basis weight in the dry state from 200 g / m2 to 1500 g / m2. The superabsorbent material may be in the form of, for example, particles, flakes or fibers. However, a liquid storage layer consisting only of a superabsorbent material, for example, a superabsorbent foam, is also conceivable. The liquid distribution layer 17 consists of a thin layer that is positioned beyond the side intended to confront the user during use, and extends over the entire surface of the absorbent structure. The liquid distribution layer 17 consists of a material with a good liquid distribution capacity, for example, a thin layer of chemically produced cellulose fluff fibers. The chemically produced cellulose fluff fibers, which consist of fine fibers of essentially pure cellulose, generally have a good liquid distribution capacity. In order to obtain a good liquid distribution capacity, said liquid distribution layer consists of a structure with fine capillaries, and said layer preferably has a high density. If appropriate, a liquid distribution layer based on cellulose also contains a small amount of superabsorbent material in the form of, for example, particles. An advantage of a liquid distribution material 17 is that said layer is capable of distributing the liquid coming from the liquid receiving layer 15 in the central portion 11 by means of the liquid distribution layer 17 outside the end portions. 12, 3 wherein the liquid can be accumulated and stored in the liquid storage layer 16. Another suitable material for the liquid distribution layer 17 is a thin layer of HIPE foam (high internal phase emulsion). Said foam is produced through the polymerization of a water-in-oil emulsion. The solid phase of the foam creates a capillary system. Figure 3 shows a longitudinal section through the absorbent structure 3 along the line III-III in Figure 2. The absorbent structure therefore has a central portion 1, a first end portion 12 and a second end portion. 13. As described in Figure 2, the absorbent structure 3 is constructed from three different layers, a liquid receiving layer 15, a liquid storage layer 16 and a liquid distribution layer 17. Figure 3 , which shows a section through the absorbent structure 3, shows that, in the dry state, the liquid receiving layer 15 in the central portion 11 is thinner than the liquid storage layer 16 in the two end portions 12, 13. Inasmuch as the liquid receiving layer 15 is thinner than the liquid storage layer 16, a lower basis weight is obtained for the material in the central portion 11 than for the material in the extreme portions 12, 13 despite the fact that the average density of! material in the central portion 11 is greater than the average density of the material in the end portions 12, 13. In this way, an absorbent structure 3 is obtained which, in an absorbent article, is discreet and comfortable for use at the same time It has a good capacity for liquid reception, liquid distribution and liquid storage. Figure 4 shows an alternative embodiment of an absorbent structure 403 according to the invention seen from the side intended to confront the user during use. The absorbent structure has a longitudinal direction V and a transverse direction VI.

The absorbent structure 403 also has a central portion 411, a first end portion 412 and a second end portion 413. In addition, the absorbent structure 403 is constructed from two different layers, a liquid receiving layer 415 and a storage layer. of liquid 416. The liquid receiving layer 415 is positioned in the central portion 411 of the absorbent structure and is intended to be positioned near the liquid-permeable surface layer when used in an absorbent article. The liquid storage layer 416 extends over the entire surface of the absorbent structure 403. The liquid storage layer 416 is intended to be positioned near the liquid-tight backing layer when the absorbent structure is used in an absorbent article. In the central portion 411 of the absorbent structure, the liquid storage layer is slightly wider in the transverse direction VI of the absorbent structure than the liquid receiving layer 415. In the central portion 411 of the absorbent structure, the layer The liquid receiving 415 is therefore placed in what is known as the wetting zone, ie in the area that is expected to be first moistened by the discharged body fluid. The liquid receiving layer 415 and the liquid storage layer 416 can of course have the same extension in the transverse direction VI, ie they have the same width.

Figure 5 shows a longitudinal section through the absorbent structure along the line V-V in Figure 4, ie a section through the absorbent structure in its longitudinal direction. Figure 5 therefore shows the central portion 411 and the two end portions 412, 413. The two end portions 412, 413 therefore consist only of the liquid storage layer 416, while the central portion 411 also comprises the liquid receiving layer 415. It can be seen from figure 5 that the thickness of the liquid storage layer 416 is greater in the two end portions 412, 413 than in the central portion 411. As the figure also shows 5, the total thickness of the absorbent structure in the two end portions is greater than the total thickness of the absorbent structure in the central portion 411. By virtue of which the absorbent structure 403 is thinner in the central portion 411 than in the two end portions 412, 413, a lower basis weight for the material is obtained in the central portion 411 than in the end portions 412, 413 despite the fact that the average density of the material in the cent portion 411 is larger than the average density of the material in the end portions 412, 413. It is also possible for the absorbent structure shown in Figures 4 and 5 to comprise a thin liquid distribution layer which is located against the storage layer of liquid 416 and is therefore positioned near the liquid-tight layer when the absorbent structure is used in an absorbent article. The diaper 100 described in Figure 1 and the absorbent structures described in Figures 2-5 constitute only some illustrative embodiments. Therefore, the shape of the diaper as well as its design in other aspects can be varied and the shape of the absorbent structure as well as its design in other respects can be varied.

Claims

REIVINDICACIO ES

1. The absorbent structure (3) for an absorbent article such as a diaper (100), an incontinence pad, a sanitary napkin or the like, the absorbent structure (3) having, in the longitudinal direction, a central portion (11) and two end portions (12, 13), characterized in that the average density of the material in the central portion (11), at least in the dry state, is greater than the average density of the material in the end portions (12, 13) and in that the central portion (11), at least in the dry state, has a lower basis weight than the end portions (12, 13), the density and the basis weight that are calculated based on the total surface area of the central portion (11) or as appropriate the total surface area of the end portions (12, 13). Absorbent structure (3) according to claim 1, characterized in that it comprises a liquid storage layer (16) and a liquid receiving layer (15), the liquid receiving layer 15 which is placed at least in the central portion (11) of the absorbent article. Absorbent structure (3) according to claim 2, characterized in that the liquid receiving layer (15) is a superabsorbent foam, the superabsorbent foam having a density in the dry state from 0.2 g / cm3 to 1.0 g / cm3 and has a basis weight in the dry state from 200 g / m2 to 800 g / m

2. Absorbent structure (3) according to claim 2, characterized in that the liquid receiving layer (15) is a foam made of regenerated cellulose. Absorbent structure (3) according to claim 2, characterized in that the liquid receiving layer (15) is a dry formed daughter containing 5-100% cellulose fibers, which has a density of 0.2 g / cm3 up to 1.0 g / cm3 and a basis weight from 30 g / m2 to 1200 g / m2, whose sheet has been formed by compression of a web containing cellulose fibers without the subsequent defibration or lint formation. Absorbent structure (3) according to any of claims 2-5, characterized in that the liquid receiving layer (15) expands in the direction of thickness of the absorbent structure (3) to wetting. Absorbent structure (3) according to any of claims 2-6, characterized in that the liquid storage layer (16) is a mixed structure made of cellulose fluff fibers and superabsorbent material. Absorbent structure (3) according to claim 7, characterized in that the liquid storage layer (16) has a density in the dry state from 0.1 g / cm3 to 0.7 g / cm3 and a basis weight in the dry state from 200 g / m2 to 1500 g / m2. Absorbent structure (3) according to any of the preceding claims, characterized in that it comprises a liquid distribution layer (17). 10. Absorbent article, such as a diaper (100), an incontinence pad, a sanitary napkin or the like, having an essentially oblong shape and comprising a liquid-permeable surface layer (1), a liquid-tight back layer ( 2) and, enclosed between these layers, an absorbent structure (3), whose absorbent structure (3) has, in the longitudinal direction, a central portion (11) and two end portions (12, 13), characterized in that the density average of the material in the central portion (11), at least in the dry state, is higher than the average density of the material in the end portions (12, 13) and in that the central portion (11), at least in the dry state, has a lower basis weight than the end portions (12, 13), the basis weight and the density that are calculated based on the total surface area of the central portion (11) or as appropriate the surface area total of the extreme portions (12, 13).