WO2003073971A2

WO2003073971A2 - Method for producing a composite absorbent structure for absorbent article, and structure formed in this way

Info

Publication number: WO2003073971A2
Application number: PCT/IT2003/000083
Authority: WO
Inventors: Claudio Giacometti
Original assignee: Claudio Giacometti
Priority date: 2002-03-01
Filing date: 2003-02-17
Publication date: 2003-09-12
Also published as: AU2003214639A8; WO2003073971A3; AU2003214639A1

Abstract

A method is described in which at least a first card web (VI), consisting at least partially of absorbent fibers, is combined with a supporting non-woven fabric (NT1) and with an acquisition and distribution layer (NT2). Particles (P) of at least one super-absorbent polymer are inserted into the composite strip material formed in this way.

Description

METHOD FOR PRODUCING A COMPOSITE ABSORBENT STRUCTURE FOR MAKING DIAPERS, SANITARY NAPKINS AND THE LIKE, AND STRUCTURE FORMED IN THIS WAY

DESCRIPTION Technical field

The present invention relates to a composite absorbent structure for producing sanitary articles such as sanitary napkins, diapers for infants, incontinence pads and similar products.

The invention also relates to a method for producing a structure of the aforesaid type. Prior art

In the production of absorbent sanitary products, there is a known way of forming complex structures comprising at least two outer layers, forming two containing shells, between which are positioned further layers having various functions, usually including a layer for acquisition and distribution of body fluids and an absorbent layer. Typically, a sanitary napkin or a diaper comprises a top sheet which is perforated or at least permeable by fluids in some way, and is designed to come into contact with the body of the wearer. The body fluids (blood, urine) to be absorbed by the product pass through the top sheet and reach the interior of the product. The top sheet typically consists of a perforated plastic film and/or a layer of non-woven fabric, or possibly composite multilayer structures, for example one or more plastic films joined to one or more strips or webs of textile fibers. Under this top sheet is placed an acquisition and distribution layer, referred to by the abbreviation ADL. The acquisition and distribution layer causes the body fluids to pass rapidly into the interior of the structure of the absorbent, and distributes them in such a way that they are distributed uniformly throughout the thickness of the underlying storage layer or core, instead of being absorbed in a localized way only in the areas underlying the arrival points of the fluid, or predominantly in these areas. Under the absorbent layer where the fluids are absorbed and stored, there is a back sheet which is impermeable to the fluids and is designed to prevent the outflow of the absorbed fluids. The various layers forming this structure are welded together normally along the edge of the product.

In particular cases, even more complex structures are used, with a greater number of layers. In the manufacture of this type of product, the problem arises of the need to assemble different initial materials supplied in the form of continuous strips, using extremely costly machinery. It would therefore be useful to have available intermediate products consisting of strip materials which carry out more than one of the functions listed above (the functions of the top sheet and of the distribution, absorption and back sealing of the product), to reduce the complexity of the production machinery.

A further problem which arises in the manufacture of absorbent products of the aforementioned type consists in the overall dimensions of the products themselves. In particular, in the manufacture of sanitary articles for use by women it would be useful to have available materials of limited thickness, in order to obtain thin absorbents which would reduce the discomfort of wearing them.

In order to resolve the aforementioned problems, at least in a partial way, composite materials have been devised which consist of two or more assembled layers, producing a structure forming an initial intermediate product to be used for making the finished product.

US-A-4287251 describes a disposable absorbent structure formed by a plurality of layers of non-woven fabric, of the entangled type for example. These layers are joined together by a bonding agent, applied in particular along the edges, or by spot welding, using thermoplastic fibers.

WO-A-9963922 describes an absorbent structure comprising a composite acquisition and distribution layer for the body fluids and one or more absorbent layers. The various layers are formed by the air-laid method, in other words by depositing a web of short fibers on a cloth through which passes a flow of air sucked from the side of the cloth opposite that on which the fibers are deposited. The absorbent layer consists of cellulose fibers, super-absorbent polymer particles and a bonding agent for consolidating the web. The super-absorbent polymer particles are mixed with the fibers before deposition on the forming cloth. The bonding agent is sprayed on to the web of fibers formed on the forming cloth and is then polymerized by passing the intermediate product through one or more kilns. The webs forming the acquisition and distribution layer are also formed by the air-laid method and are consolidated by the addition of a bonding agent which is thermally polymerized. Alternatively, the webs are consolidated by fusion of thermoplastic fibers present in the mixtures used for forming the webs. The different layers are joined together in a similar way, by means of hot-cross-linked bonding agents or by the partial fusion of the thermoplastic fibers.

US-A-5,695,486 describes a composite absorbent structure formed by air-laid methods, in which the webs are consolidated by the addition of bonding agents. The formation of non-woven layers by air-laid methods has the advantage of enabling particles of a super-absorbent polymer (SAP) to be introduced and mixed intimately with the fibers before the formation of the web. Super-absorbent polymers enable the fluid absorption capacity of the absorbent layer to be increased considerably. However, this method also has some drawbacks, including the complexity of the plant required for this type of production and the necessity of using bonding agents for consolidating and joining the fibers to form a layer having sufficient mechanical consistency. Alternatively, it is necessary to use thermoplastic fibers and hot-calendering systems. The methods of consolidating the fibers are a critical aspect, particularly in view of the fact that the fibers used for forming the webs by the air-laid method are very short. The finished product has a relatively low mechanical strength which is a disadvantage in the subsequent stages of conversion of the intermediate product for the manufacture of the finished product. Furthermore, the use of randomly oriented short fibers gives rise to another problem, in the form of the non-optimal distribution of the fluids in the absorbent layer. This is because the body fluids are released in a rather limited area on the top sheet of the absorbent product. From here they pass into the underlying absorbent layer of a product whose longitudinal dimension is greater than the transverse dimension. When the fibers are distributed in a random way, the fluid is distributed in the absorbent layer, creating a wet area extending in an approximately circular shape, and then reaches the lateral edge areas of the product without impregnating the portions of absorbent material lying closer to the longitudinal ends, in other words those farther from the point of entry of the fluid. This causes, on the one hand, a failure to use the absorbent material in large areas of the product, and, on the other hand, the risk of lateral leakage of the fluid. EP-B-0168196 describes a different method of distributing particles or powders of a super-absorbent polymer in a web product for the production of sanitary napkins. According to this method, the particles are deposited on the top sheet of a web and a second web is applied on top of them. The two webs are joined by embossing, so that the particles remain trapped between the two webs. The resulting structure has a low mechanical strength, which is a disadvantage at the stage of using the multilayer absorbent structure in sanitary napkin or diaper production lines. Objects and summary of the invention

The object of the present invention is to provide a continuous sheet material which at least partially overcomes one or more of the drawbacks of the conventional products.

More particularly, the object of the present invention is to provide a method which makes it possible to obtain, with low production costs, absorbent structures having high mechanical strength and high absorption, which can be advantageously used as intermediate products in the manufacture of sanitary napkins, diapers for infants, incontinence pads, and the like.

Another object of the present invention is to provide a composite multilayer structure of high strength for the aforesaid applications. Essentially, according to the invention a method or process is provided for producing a composite absorbent strip material, comprising at least a first layer for acquisition and distribution of a fluid and a second absorbent layer for absorbing and storing said fluid, in which at least a first card web, consisting at least partially of absorbent fibers, is combined with a supporting non-woven fabric and with said acquisition and distribution layer, particles of at least one super-absorbent polymer being inserted into said composite strip material.

The combination of the acquisition and distribution layer with the absorbent core and with the supporting non-woven fabric makes it possible to obtain an intermediate product with a high absorption capacity, having reduced thickness and high strength, which drastically simplifies the converting operations by which this intermediate product is formed into the finished product. The process of manufacturing the intermediate product is also simple, and can be carried out by machinery which is not complicated and which is therefore inexpensive and easy to maintain.

In a particularly advantageous embodiment of the invention, the method can comprise the following steps: placing particles of at least one super-absorbent polymer between a first card web and a second card web formed at least partially from absorbent fibers, and forming an absorbent core comprising said first and second card web and the polymer particles interposed between them; combining a supporting non-woven fabric with a first side of said core; combining the acquisition and distribution layer with a second side of said core; joining together: the acquisition and distribution layer; the first and second webs which, with the super-absorbent polymer particles, form said core; and the supporting non-woven fabric.

Thus the absorbent core has an even higher absorption capacity and the super-absorbent polymer particles are retained in a reliable way within the structure, so that a uniform distribution is maintained. The mechanical strength of the material is increased by the use of two carded fiber webs, which, when consolidated, impart mechanical strength to the product. The type of materials used also makes it possible to obtain high fluid absorption capacities with very thin products, with consequent advantages in production, packaging and transport, but above all with advantages of greater comfort for the user. The fibers forming the card web or webs can be what are known as staple fibers, in other words fibers with a length in the range from 15 to 60 mm and preferably from 30 to 60 mm, both for the webs forming the core and for the web forming the acquisition and distribution layer.

The super-absorbent polymer particles can be powders, flocks, granules, or other types. The super-absorbent polymer that is used can be any polymer specified for the manufacture of absorbent products, for example one of the polymers listed in EP-A-0168196.

In this description and in the attached claims, reference will frequently be made to a card web. It shall be understood that this web can also be a multiple web, in other words one produced by superimposition of a plurality of layers of carded fibers which may also originate from a plurality of carding machines in series. These layers form a structure of adequate thickness and will be subsequently consolidated to form a single non-woven layer.

In practice, the first card web can be placed, in other words superimposed, on the supporting non-woven fabric, while the following are then placed in sequence on the free surface of the first card web: the super-absorbent polymer particles, the second card web, and the acquisition and distribution layer. The acquisition and distribution layer, the card web or webs with the super-absorbent polymer particles (interposed between the above or between the card web and one of the adjacent non-woven and acquisition and distribution layers), and the supporting non-woven fabric can be joined together in various ways. In a possible embodiment of the method of the present invention, this joining is achieved by a hot working process, for example by calendering, in other words by passing the composite structure resulting from the superimposition of the various components through a nip between two rolls, at least one of which is heated and at least one of which can be provided with protuberances. The temperature of the roll or rolls and the speed of advance of the material between the rolls are advantageously kept at levels such as to cause at least a partial melting of at least one of the components of the fiber mixture, for example of the part with a lower melting point of any bi-component fibers used in the mixtures, or of any suitable heat- sensitive component. The term "heat-sensitive" denotes in a general way a component, particularly a fiber, which melts at the temperature at which the various layers forming the structure are consolidated, to impart cohesion. The partial and spot melting at the positions of the protuberances of the roll results in spot welding between the different layers forming the structure.

Alternatively, the low-melting or heat-sensitive components of the different layers can be melted by blowing hot air on to the material.

In a particularly advantageous embodiment, the different webs or layers are welded together in another way, by an ultrasonic welding process. The shape and distribution of the welding areas can be selected appropriately in order to retain the super-absorbent polymer particles so that they will retain the most uniform distribution possible within the absorbent core.

When the different component layers of the absorbent layer are joined together by a thermal method (by calendering, by hot air, by ultrasound, or by another method), a heat-sensitive component must be provided in the mixture of fibers used to form at least the card web or webs forming part of the absorbent core. Thus the heat that melts the component consolidates the card web or webs and also produces a mutual adhesion between them and the supporting non-woven fabric and the acquisition and distribution layer. Additionally, when the acquisition and distribution layer is made from an initial card web produced in line and placed directly on top of the web or webs forming the absorbent core, the layer must contain a heat-sensitive component in order to achieve the consolidation of its component fibers. In general, since the acquisition and distribution layer is essentially non- absorbent, it consists predominantly of heat-sensitive fibers.

Conversely, the supporting non-woven fabric can be made without heat-sensitive components; for example, it can consist entirely of natural fibers. In this case, the adhesion to the card web adjacent to it is brought about by the melting of the heat-sensitive fibers present in the card web itself. In such a case, the supporting non-woven fabric will be a non-woven fabric which is consolidated, for example, by a mechanical method (needling). It is, however, preferable for the supporting non-woven fabric to consist wholly or partially of heat-sensitive fibers and to be consolidated by a thermal method, being, for example, what is called a thermobonded textile.

In a different embodiment, the various component layers and webs of the composite structure can be joined by an entangling or needling process.

As mentioned above, the acquisition and distribution layer can consist of a card web which is produced in line and is directly placed on the card web or webs forming the absorbent core, and is therefore consolidated during the stage at which the various layers forming the absorbent structure are joined together (by needling, by a thermal method or in another way). Preferably, in a different embodiment, it consists, in turn, of a non-woven fabric produced previously and suitably consolidated. For example, it can be a non-woven fabric consisting of one or more card webs which have been needled or consolidated by other known methods, by heat for example (thermobonded). The acquisition and distribution layer can consist of a single web of consolidated fibers, a plurality of identical webs of consolidated fibers, or two or more layers or webs joined together and formed from fibers of different kinds and/or with different physical characteristics, to facilitate the acquisition and distribution functions respectively. The acquisition and distribution layer preferably consists for the most part of essentially non-absorbent fibers. In particular, it is possible to use non- absorbent fibers made from one or more of the following materials: polyester; polyethylene; polypropylene; bi-component polyethylene and polypropylene fibers; bi-component polyamide and polyester fibers; and bi-component polyester and polyethylene fibers. Fibers of absorbent material, such as viscose, cellulose and cotton, can be used in combination with the preceding fibers, preferably in smaller quantities. The non-absorbent fibers can be hydrophilic or hydrophobic. The fibers of this layer have, for example, a count in the range from 1 to 15 dtex, and preferably from 3 to 10 dtex.

The card webs forming the absorbent core consist predominantly of absorbent fibers. As mentioned above, when the various layers are consolidated by thermal means, the webs forming the core also comprise fibers of heat-sensitive materials, in other words thermoplastic fibers. These webs can generally comprise fibers formed from one or more of the following materials: viscose, cellulose, cotton as absorbent materials; polypropylene, bi- component polyethylene and polypropylene fibers; bi-component polyethylene and polyester fibers; and bi-component polyamide and polyester fibers.

The fibers of these webs have, for example, a count in the range from 1 to 15 dtex, and preferably from 1 to 2 dtex.

When at least two card webs are provided for forming the absorbent core, these can consist of mixtures of fibers which are different from each other.

In order to facilitate the distribution of the fluids in the final absorbent product, the acquisition and distribution layer is advantageously formed from fibers oriented with a preferential distribution parallel to the direction of the longitudinal extension of said strip material. Alternatively, or in combination with the above, one or both of the webs forming the absorbent core consist of fibers oriented in the longitudinal direction of the material. Since the final absorbent product has an elongated structure, and since a portion of the strip material cut parallel to the direction of the machine, in other words parallel to the longitudinal direction of the material, is inserted into it, the orientation of the fibers in this direction provides an optimal exploitation of the whole absorbent structure. This is because, while the body fluids are released in a restricted area located approximately at the center of the absorbent product, the preferential orientation of the fibers in the longitudinal direction of the absorbent product causes the fluids to be distributed throughout the whole product, and therefore produces a distribution throughout the internal absorbent volume.

The acquisition and distribution layer advantageously has a thickness in the range from 0.15 to 3 mm and a weight per unit of surface area approximately in the range from 10 to 80 g/m².

The absorbent core advantageously has a thickness in the range from 0.2 to 3 mm for example, and a weight per unit of surface area in the range from 20 to 200 g/m², excluding the weight of the super-absorbent polymer. The percentage of the latter can be in the range from approximately 5% to approximately 70% of the weight of fiber forming the absorbent core. Brief description of the drawings

The invention will be more clearly understood with the aid of the description and the attached drawing, which shows non-restrictive practical embodiments of the invention. More particularly,

Fig. 1 shows a diagram of an installation for applying the method of the present invention in a first embodiment;

Fig. 2 shows a diagram of an installation for applying the method of the present invention in a second embodiment;

Fig. 3 shows an enlarged and highly schematic local cross section of the structure according to the invention in a possible embodiment. Detailed description of the preferred embodiments of the invention

Fig. 1 shows schematically a first embodiment of an installation for the application of the method according to the invention. The installation comprises a first carding machine 1 and a second carding machine 3, which produce corresponding card webs indicated as V1 and V3. The card web V1 , which is not consolidated, in other words not made cohesive, is deposited so that its lower surface lies on a first layer of non-woven fabric NT1 , supplied from a first reel R1 which is gradually unwound. The layer of non-woven fabric

NT1 can consist of a layer of non-woven fabric produced by the consolidation of a card web or a different type of non-woven fabric, for example one made cohesive by the use of adhesives or by partial melting of thermoplastic fibers contained in the mixture of fibers forming the non-woven fabric. A suitable quantity of particles P of one or more super-absorbent polymers supplied from a hopper 5 is deposited on the upper surface of the web V1 , opposite the surface in contact with the layer of non-woven fabric NT1. For example, a quantity of particles forming a proportion by weight of 5- 70% of the total weight of the webs V1 and V2 can be distributed.

The web V3 produced by the carding machine 3 is deposited on the web V1 down line from the area of application of the super-absorbent polymer particles P, in such a way that these particles remain contained between the two webs V1 and V3. The two webs V1 and V3 and the layer of super- absorbent polymer particles P are designed to form the absorbent core of the structure.

A non-woven fabric NT2 unwound from a second reei R2 forms the layer for acquisition and distribution of the fluids, and is deposited on the upper surface of the web V3. The non-woven fabric NT2 can consist of a consolidated card web or another non-woven fabric having suitable characteristics.

The assembly of the webs V1 , V3, the particles P retained between them and the non-woven fabrics NT1 , NT2 is then passed through a calender 9, which in the illustrated example comprises a plain roll 11 and a roll 13 provided with protuberances. The two rolls are pressed against each other and one or both of the rolls are heated to a sufficient temperature to melt at least one of the thermoplastic fibers forming the various superimposed layers, to achieve the mutual welding. The composite material obtained in this way is wound onto a reel R3 for subsequent use in a production line for absorbent articles or products. The composite material will form the inner part of the sanitary napkin or diaper. A portion of this material, suitably shaped, will be enclosed between two shells forming the fluid-permeable top sheet and the impermeable back sheet. Other layers or components can then be added to complete the structure of the final product, as required by the producer.

The various components NT1 , NT2, V1 and V3 can also be joined together by a different joining method. For example, they can be spot welded, possibly by an ultrasonic system of a known type. Alternatively, a needling system can be used, with a needling plate in place of the calender 9. A solution using a joining system of this type is shown in Fig. 2.

In this second example of embodiment, where identical numbers indicate parts which are identical or equivalent to those of Fig. 1 , a third card web V4, supplied from a third carding machine 4, is provided in place of the non-woven fabric NT2 and forms the acquisition and distribution layer. The assembly formed by the non-woven fabric NT1 and the three unconsolidated card webs V1 , V3 and V4 with the super-absorbent polymer particles P enclosed between the webs V1 and V3 is passed through a needling station 15, with a needling plate 17. The needling consolidates the card webs and joins together the various layers making up the multilayer structure, which is then wound to form a reel R3. Fig. 3 shows schematically an enlarged local cross section through the end product. The absorbent core or layer consists of the components NT1 , V1 , V3 and P, while the acquisition and distribution layer consists of the non- woven fabric NT2 in the example of Fig. 1 and consists of the web V4 in the example of Fig. 2. In both of the illustrated examples of embodiment, the super-absorbent polymer particles P could be deposited directly on the supporting non-woven fabric NT1 before the web V1 is deposited on the latter. Alternatively, the particles could be deposited on the web V3 and could then be placed between the latter and the acquisition and distribution layer NT2, although this would not be particularly advantageous, since it is preferable to interpose a layer of absorbent fibers between the super-absorbent polymer particles and the acquisition and distribution layer.

When two webs V1 and V3 are used, as in the illustrated examples, the flow of the body fluid towards the super-absorbent particles can be promoted by making the web V3 from predominantly non-absorbent and hydrophilic fibers, while the web V1 is made with a predominance of absorbent fibers.

It is to be understood that the drawing shows only some possible embodiments of the invention, which can be varied in its forms and arrangements without departure from the scope of the basic principle of the invention.

Claims

1. Method for making an absorbent composite strip material, comprising at least a first layer for acquisition and distribution of a fluid and a second absorbent layer for absorbing and storing said fluid, in which at least a first card web, consisting at least partially of absorbent fibers, is combined with a supporting non-woven fabric and with said acquisition and distribution layer, particles of at least one super-absorbent polymer being inserted into said composite strip material.

2. Method according to Claim 1 , comprising the steps of: - placing said particles of at least one super-absorbent polymer between a first card web and a second card web, said second card web being formed at least partially from absorbent fibers and forming, together with said first card web and with said super-absorbent polymer particles, an absorbent core; - combining said supporting non-woven fabric with a first side of said absorbent core; combining said acquisition and distribution layer with a second side of said absorbent core; joining together: the acquisition and distribution layer; the first and the second webs which, together with the super-absorbent polymer particles inserted therebetween, form said core; and the supporting non-woven fabric.

3. Method according to Claim 2, in which said first card web is placed on said supporting non-woven fabric, while the following are then placed in sequence on the free surface of the first card web: the super-absorbent polymer particles, the second card web, the acquisition and distribution layer.

4. Method according to Claim 1 , 2 or 3, in which the acquisition and distribution layer, the card web or webs and the supporting non-woven fabric are joined together by a hot working process.

5. Method according to Claim 1 , 2 or 3, in which the acquisition and distribution layer, the card web or webs and the supporting non-woven fabric are joined together by spot welding.

6. Method according to Claim 5, in which said spot welding is carried out by means of ultrasound.

7. Method according to Claim 1 or 2, in which the acquisition and distribution layer, the card web or webs and the supporting non-woven fabric are joined together by means of hot air.

8. Method according to Claim 4, 5, 6 or 7, in which heat-sensitive fibers are inserted into said card web or webs, the melting of these fibers producing said joining together and the consolidation of the fibers forming said web or webs.

9. Method according to Claim 1 or 2, in which the acquisition and distribution layer, the card web or webs and the supporting non-woven fabric are joined together by needling.

10. Method according to one or more of the preceding claims, in which said acquisition and distribution layer consists of one or more unconsolidated card webs, which are consolidated at the stage of joining to the other components of the composite strip material.

11. Method according to one or more of Claims 1 to 9, in which said acquisition and distribution layer consists of a non-woven fabric consolidated before the combination with said core.

12. Method according to one or more of the preceding claims, in which said acquisition and distribution layer itself consists of two layers of fibers having different characteristics.

13. Method according to one or more of the preceding claims, in which said acquisition and distribution layer consists principally of essentially non-absorbent fibers.

14. Method according to one or more of the preceding claims, in which said acquisition and distribution layer is formed from fibers oriented with a preferential distribution parallel to the direction of the longitudinal extension of said strip material.

15. Method according to one or more of the preceding claims, in which at least one of said first and second card webs consists of fibers oriented with a preferential distribution parallel to the direction of the longitudinal extension of said strip material.

16. Method according to one or more of the preceding claims, in which said supporting non-woven fabric is a consolidated card web.

17. Multilayer absorbent structure comprising at least a first layer for acquisition and distribution of a fluid, formed predominantly from essentially non-absorbent fibers, and a second absorbent layer for absorbing and storing said fluid, characterized in that said second layer comprises particles of at least one super-absorbent polymer and at least one card web joined to a supporting non-woven fabric layer placed on the opposite side of said web from said first acquisition and distribution layer.

18. Structure according to Claim 17, characterized in that said second layer comprises said first card web and a second card web joined thereto, the particles of said at least one super-absorbent polymer being placed between the first card web and the second card web.

19. Structure according to Claim 17 or 18, characterized in that said first layer consists of one or more webs of carded fibers.

20. Structure according to Claim 17 or 18 or 19, characterized in that said first layer consists of a non-woven fabric.

21. Structure according to one or more of Claims 17 to 20, characterized in that the fibers of the first layer are oriented with a preferential distribution parallel to the longitudinal extension of the structure.

22. Structure according to one or more of Claims 17 to 21 , characterized in that the fibers of said first and/or of said second card web of the second layer are oriented with a preferential distribution parallel to the longitudinal extension of the structure.

23. Structure according to one or more of Claims 17 to 22, characterized in that said first and if necessary said second card web of the second layer are formed from staple fibers.

24. Structure according to Claim 23, characterized in that said first and if necessary said second card web of the second layer are formed from fibers having a length in the range from approximately 15 to approximately 60 mm and preferably from approximately 30 to approximately 60 mm.

25. Structure according to one or more of Claims 17 to 24, characterized in that said first layer is formed from fibers having a length in the range from approximately 15 to approximately 60 mm and preferably from approximately 30 to approximately 60 mm.

26. Structure according to one or more of Claims 17 to 25, characterized in that the fibers of the first layer have a count in the range from approximately 1 to approximately 15 dtex and preferably from approximately 3 to approximately 10 dtex.

27. Structure according to one or more of Claims 17 to 26, characterized in that the fibers of the second layer have a count in the range from approximately 1 to approximately 15 dtex and preferably from approximately 1 to approximately 2 dtex.

28. Structure according to one or more of Claims 17 to 27, characterized in that said first layer, said first web, and if necessary said second web and said supporting non-woven fabric are joined together by needling.

29. Structure according to one or more of Claims 17 to 27, characterized in that said first layer, said first web, and if necessary said second web of the second layer and said supporting non-woven fabric are joined together by spot welding.

30. Structure according to one or more of Claims 17 to 27, characterized in that said first layer, said first web, and if necessary said second web of the second layer and said supporting non-woven fabric are joined together by the melting of a heat-sensitive component.

31. Structure according to one or more of Claims 17 to 30, characterized in that said first card web and if necessary said second card web contain absorbent fibers and heat-sensitive fibers.

32. Structure according to one or more of Claims 17 to 31 , characterized in that the acquisition and distribution layer has a thickness in the range from 0.15 to 3 mm.

33. Structure according to one or more of Claims 17 to 32, characterized in that the acquisition and distribution layer has a weight per unit of surface area in the range from approximately 10 to approximately 80 g/m².

34. Structure according to one or more of Claims 17 to 33, characterized in that the absorbent core has a thickness in the range from approximately 0.2 to approximately 3 mm.

35. Structure according to one or more of Claims 17 to 34, characterized in that the absorbent core has a weight per unit of surface area in the range from approximately 20 to approximately 200 g/m², excluding the weight of the super-absorbent polymer.

36. Structure according to one or more of claims 17 to 35, characterized in that the absorbent core contains a proportion by weight of super-absorbent polymer in the range from approximately 5% to approximately 70% of the weight of fiber forming the absorbent core.