EP0826811B1 - Absorbent nonwoven composite material with a soft surface and a rough surface, and method for its production - Google Patents

Description

Nowadays, many products for domestic, clothing, hygienic, medical, industrial ... based on fibrous materials, are made from so-called "nonwoven" textile structures.

Among these items, in addition to wiping materials in the form of relatively thin sheets, comparable to paper, but having very high absorption properties, it has been proposed to produce real sponge substitutes whose dimensions (length, width and above all thickness) can vary within wide limits depending on the intended use. As an indication, the thickness can be of the order of a few tenths of a millimeter when making a wiping "cloth" to reach a centimeter or even more for articles of the type "sponge", the grammage being able to vary from 30 g / m2 to 200 g / m2, or even more.

To make these items, one of the three techniques for obtaining nonwovens is used, namely the technique so-called "dry process" which consists of making a veil of fibers mechanically or aerodynamically, using conventional textile machines such as openers, carding machines, or the so-called "wet" technique, technique derived from conventional papermaking, which consists in making a suspension of fibers which are received in the form of a sheet, or the so-called "melted" technique of producing a web of continuous filaments synthetics randomly oriented with respect to each other, directly at the outlet of the extrusion dies of said filaments.

It has been proposed for a long time to use these technologies to produce multilayer articles, so to have different properties on the two sides of the formed sheet, for example a printable or waterproof face and the other fibrous face, or an impermeable face and another face having a great absorption power.

• la première nappe est constituée pour tout ou partie de fibres synthétiques thermofusibles sélectionnées de préférence dans la classe des polyoléfines ; avantageusement, cette nappe est constituée d'un mélange de fibres cellulosiques ou autres et de fibres synthétiques thermofusibles, le pourcentage de ces dernières dans la nappe étant supérieur à 30 % et de préférence supérieur à 50 % ;
• la seconde nappe est, quant à elle, constituée de fibres naturelles et/ou artificielles et/ou synthétiques ayant une température de fusion plus élevée que ces dernières ;
• l'association des nappes élémentaires est réalisée en les soumettant à un traitement permettant de ré-orienter les fibres synthétiques de la première nappe pour que, d'une part, elles soient intimement liées dans la structure de la seconde nappe et, d'autre part, présentent des extrémités libres ou bouclettes apparentes sur l'une des faces extérieures du complexe formé.

The present invention relates to a new type of absorbent nonwoven complex consisting of at least two superposed fibrous sheets, linked together by interpenetration of the fibers in the direction of the thickness, characterized in that:

• the first layer consists of all or part of synthetic hot-melt fibers preferably selected from the class of polyolefins; advantageously, this sheet consists of a mixture of cellulosic or other fibers and of hot-melt synthetic fibers, the percentage of the latter in the sheet being greater than 30% and preferably greater than 50%;
• the second layer, for its part, consists of natural and / or artificial and / or synthetic fibers having a higher melting temperature than the latter;
• the association of the elementary plies is carried out by subjecting them to a treatment making it possible to re-orient the synthetic fibers of the first ply so that, on the one hand, they are intimately linked in the structure of the second ply and, on the other hand, have free ends or visible loops on one of the outer faces of the complex formed.

Documents EP-A-0333211 and EP-A-0577156, whose content is identical describe a method of manufacture of a nonwoven material resulting from the intertwining of synthetic fibers from a first layer, with fibers of a second layer. According to these documents, the complex obtained can be subjected to a thermal bonding treatment to increase the hardness or resistance of materials for bonding synthetic fibers between them without their structure being deteriorated.

The complex obtained being subjected to a treatment to merge the free ends of the fibers synthetics of the first layer making the latter abrasive by the formation of droplets at the place of the fusion.

The way in which the elementary layers are associated will depend on the nature of said layers.

• par exemple dans le cas où les deux nappes élémentaires sont obtenues selon la technique dite par voie humide ou papetière, leur réalisation sera faite sur une machine permettant d'obtenir et de superposer deux jets correspondant chacun à l'une des nappes ; dans ce cas, la superposition se fera en ligne, avant même séchage, et on procédera au complexage par l'action de jets d'eau sous pression ;
• dans le cas où les deux nappes élémentaires sont obtenues selon la technique dite par sèche, dite aussi textile, elles seront également superposées et leur liaison sera obtenue par un traitement d'enchevêtrement par jets d'eau ;
• enfin, dans le cas où l'on réalise un complexe à partir de deux nappes obtenues par des techniques différentes, il sera possible de prélier légèrement l'une ou l'autre des nappes par un enchevêtrement obtenu au moyen de jets d'eau en évitant des liaisons bloquantes de type chimique ou thermique ; les deux nappes sont ensuite superposées et liées par enchevêtrement par jets d'eau.

As an indication but not limiting, this association could, for example, be carried out as follows:

• for example in the case where the two elementary layers are obtained according to the so-called wet or paper technique, their production will be done on a machine making it possible to obtain and superimpose two jets each corresponding to one of the layers; in this case, the superposition will be done in line, before even drying, and the complexing will be carried out by the action of jets of water under pressure;
• in the case where the two elementary layers are obtained according to the so-called dry technique, also called textile, they will also be superimposed and their connection will be obtained by a tangle treatment by water jets;
• finally, in the case where a complex is produced from two layers obtained by different techniques, it will be possible to slightly prelude one or the other of the layers by a tangle obtained by means of water jets in avoiding blocking bonds of chemical or thermal type; the two layers are then superimposed and linked by entanglement by water jets.

• les fibres synthétiques entrant dans la composition de la première nappe, sont de préférence des fibres de polypropylène ou de polyéthylène :
  • dont le titre est supérieur 5 dtex, la limite haute étant directement en relation avec la pression du fluide d'enchevêtrement da manière à assurer la solidarité des fibres avec le reste de la nappe ; la limite supérieure des fibres sera fonction des disponibilités commerciales qui, à ce jour, proposent des fibres ayant un titre de 17 dtex;
  • dont la longueur est supérieure à 5 mm, la limite supérieure dépendant essentiellement de la technique de fabrication ; ainsi, un titre plus fin entraíne l'utilisation de fibres plus courtes et, la technique par voie humide nécessite une coupe plus courte que la technique par voie sèche ;
  • dont la surface est la moins ronde possible ; ainsi, on utilisera de préférence des fibres multilobées, fibrillables ou à section aplatie, qui sont beaucoup plus réceptives à l'action des jets du fluide d'enchevêtrement;
• s'il est préférable d'utiliser des fibres de polyoléfines ayant comme caractéristique d'avoir une densité inférieure à 1, il peut cependant être envisagé d'utiliser d'autres types de fibres, par exemple des fibres constituées d'un copolymère de chlorure de vinyle (85 %) et d'acétate de vinyle (15 %) dont la température de fusion est de l'ordre de 160 °C avec une densité de 1,37 g/cm3 ;
• comme fibres naturelles et/ou artificielles, on peut utiliser tout type de fibres permettant d'obtenir un caractère absorbant, tel que pâte de bois, coton, linters, viscose ; dans le cas d'une fibre chimique telle que la viscose, elle sera éventuellement de section multilobée ou fibrillable de manière à optimiser l'action des jets de fluide;
• si l'on introduit des fibres synthétiques de structure dans la seconde nappe, celles-ci auront un point de fusion supérieur à celles entrant dans la composition de la première nappe ; on utilisera par exemple des fibres de polyester ou de polyamide 6.6 (de préférence à des polyamides 6), éventuellement frisées;
• il est possible d'ajouter éventuellement dans l'une ou l'autre des nappes un certain pourcentage de fibres dites liantes, par exemple fibres bi-componantes, dont tout ou partie de la fibre flue sur les fibres voisines lors d'un traitement thermique permettant de réaliser un "collage" rendant les fibres solidaires ; dans un tel cas, le point de fusion de la partie liante de ces fibres liantes sera inférieur au point de fusion des fibres de structure précédemment citée, mais il peut cependant être inférieur ou supérieur à celui des fibres de la première nappe destinées à apporter l'effet "grattant";
• après superposition des deux nappes, le complexe résultant reçoit un traitement thermique destiné, d'une part, à révéler la pouvoir liant des fibres liantes qui ont été éventuellement introduites, et d'autre part et surtout, à fusionner les extrémités libres des fibres synthétiques de la première nappe de manière à amplifier l'effet "grattant";
• avant ou après traitement thermique, il est éventuellement possible de réaliser des traitements additionnels mécaniques, tels que par exemple crêpage ou utilisation d'un appareil de type Micrex destiné à assouplir le produit ou chimiques, tels que :
  • additions d'émulsions polymères de type latex destinées à renforcer mécaniquement le produit,
  • addition d'assouplissants chimiques,
  • additions d'agents hydrophiles,
  • imprégnation de liquides dégraissants (type liquide vaisselle), protecteurs pour la peau, détachants...

Advantageously and in practice, in accordance with the invention:

• the synthetic fibers used in the composition of the first layer, are preferably polypropylene or polyethylene fibers:
  • whose titer is greater than 5 dtex, the upper limit being directly related to the pressure of the entangling fluid so as to ensure the solidarity of the fibers with the rest of the sheet; the upper limit of the fibers will depend on the commercial availabilities which, to date, offer fibers having a titer of 17 dtex;
  • the length of which is greater than 5 mm, the upper limit essentially depending on the manufacturing technique; thus, a finer title leads to the use of shorter fibers and, the wet technique requires a shorter cut than the dry technique;
  • whose surface is as round as possible; thus, use will preferably be made of multilobed, fibrillable or flattened section fibers, which are much more receptive to the action of the jets of the entangling fluid;
• if it is preferable to use polyolefin fibers having the characteristic of having a density of less than 1, it may however be envisaged to use other types of fibers, for example fibers made of a chloride copolymer vinyl (85%) and vinyl acetate (15%) whose melting temperature is around 160 ° C with a density of 1.37 g / cm3;
• as natural and / or artificial fibers, it is possible to use any type of fiber making it possible to obtain an absorbent character, such as wood pulp, cotton, linters, viscose; in the case of a chemical fiber such as viscose, it will possibly be of multi-lobed or fibrillable section so as to optimize the action of the fluid jets;
• if synthetic fibers of structure are introduced into the second layer, these will have a higher melting point than those used in the composition of the first layer; polyester or polyamide 6.6 fibers (preferably polyamides 6) will be used, for example, crimped;
• it is possible to optionally add to one or the other of the sheets a certain percentage of so-called binder fibers, for example two-component fibers, all or part of the fiber flowing over neighboring fibers during a heat treatment making it possible to "bond" the fibers together; in such a case, the melting point of the binder part of these binder fibers will be lower than the melting point of the fibers of the above-mentioned structure, but it may however be lower or higher than that of the fibers of the first ply intended to provide the 'scratching effect;
• after superposition of the two layers, the resulting complex receives a heat treatment intended, on the one hand, to reveal the binding power of the binding fibers which have been optionally introduced, and on the other hand and above all, to merge the free ends of the synthetic fibers of the first layer so as to amplify the "scratching"effect;
• before or after heat treatment, it is possibly possible to carry out additional mechanical treatments, such as, for example, creping or use of a device of the Micrex type intended to soften the product or chemicals, such as:
  • additions of latex-type polymer emulsions intended to mechanically reinforce the product,
  • addition of chemical softeners,
  • additions of hydrophilic agents,
  • impregnation of degreasing liquids (type dishwashing liquid), skin protectants, stain removers ...

The respective grammages of the two layers are adapted according to the applications, these grammages being able go from 15 to 200 g / m2 for the second layer and from 10 to 70 g / m2 for the first layer.

The invention also relates to a method for producing such a product, said method consisting in make two layers of elementary fibers, the two layers being linked together downstream of the formation zone by a needling treatment by jet of fluid acting at least against the surface of the sheet comprising the fibers hot-melt intended to constitute the "scraping" side of the complex article formed.

The nonwoven complex formed is then dried and receiving additional heat treatment allowing partial fusion of the ends chemical fibers from the first layer that remain linked to the basic nonwoven complex.

For the implementation of such a process, one can use for example a conventional machine for obtaining of a wet nonwoven, for example a machine of the Hydroformer type from the company VOITH, at the outlet of which is arranged a hydraulic binding assembly, also of known type, for example a processing machine by pressurized water jet needles of the "Jet Lace" type from ICBT-PERFOJET, this machine being adjusted so that the jets act preferentially on the face of the multilayer material constituted by the sheet which contains the hot-melt synthetic fibers, which makes it possible to redirect said fibers in the Z direction of the sheet and sort of "file" them inside it.

When the two elementary layers are made wet, their association is obtained on the canvas drainage before treatment with fluid jets.

It is also possible to envisage making the second layer by the dry route, the association being carried out at the exit of the formation of this layer by relating to its surface, on the side where the action of the jets of fluid will be exerted interlacing, the first veil made wet or dry. In such a case, the two overlapping layers are preferably rewetted before subjecting them to the action of the entanglement jets.

After production, the nonwoven complex formed is dried and then optionally impregnated with chemical binders. acrylic base (possibly copolymerized), ethylene-vinyl-acetate, polyurethane ... as well as various additives allowing to reinforce properties specific such as hydrophilicity, flexibility.

After drying, preferably, on the same machine, a heat treatment to cause partial melting of ends of chemical fibers in the upper layer which remain bonded to the basic nonwoven complex, the molten ends increasing and magnifying the effect of roughness.

The invention and the advantages which it brings will however be better understood thanks to the example embodiments given below for information but not limiting.

These examples are made on a paper machine conventional VOof hydroformer type, adapted to include two separate suspension arrivals and therefore allowing production a multi-layer sheet.

At the outlet of this machine, there is an installation interlacing by fluid jets sold by the company ICBT-PERFOJET under the name JET-LACE, this machine comprising four rows of injectors allowing the complex to be subjected to the action of jets / needles obtained from water under pressure included between 10 bars and 125 bars. The number of jets / needles per meter of width of each row can vary from 800 to 1700 and is advantageously around 1000, the diameter of each injector orifice being generally between 100 and 140 microns, but possibly reaching a value of 300 microns.

Example 1

• pour la couche supérieure qui sera ultérieurement soumise à l'action préférentielle des jets d'aiguilletage, et qui constitue globalement 23 % de la masse fibreuse totale du complexe après formation, une suspension d'un mélange comportant :
  • 50 % de fibres de polypropylène (titre 6,7 dtex, coupe 6 mm, section ronde) ; ces fibres sont teintées dans la masse, ce qui permet, dans le produit final, de pouvoir identifier visuellement les différentes couches du produit fini.
  • 50 % de fibres cellulosiques constituées de fibres papetières longues obtenues à partir de pin sylvestre.
• pour la couche inférieure formant la seconde nappe souple et avantageusement absorbante, et qui constitue globalement 77 % de la masse totale fibreuse dans le complexe final, une suspension comprenant :
  • 67 % de fibres cellulosiques longues obtenues à partir de pin sylvestre,
  • 33 % de fibres de polyester titre 1,7 dtex - coupe 18 mm - section ronde.

On a paper machine of the aforementioned type, a nonwoven complex is produced in accordance with the invention from two fibrous suspensions having the following compositions:

• for the upper layer which will subsequently be subjected to the preferential action of the needling jets, and which overall constitutes 23% of the total fibrous mass of the complex after formation, a suspension of a mixture comprising:
  • 50% polypropylene fibers (6.7 dtex, 6 mm cut, round section); these fibers are dyed in the mass, which allows, in the final product, to be able to visually identify the different layers of the finished product.
  • 50% of cellulose fibers made up of long paper fibers obtained from Scots pine.
• for the lower layer forming the second flexible and advantageously absorbent sheet, and which globally constitutes 77% of the total fibrous mass in the final complex, a suspension comprising:
  • 67% of long cellulosic fibers obtained from Scots pine,
  • 33% polyester fibers, title 1.7 dtex - cut 18 mm - round section.

The two tablecloths are superimposed so that the tablecloth with polypropylene fibers are at the top and, before drying, the complex is subjected to an entangling action by water jets, the four successive series of jets being obtained from of water under increasing pressure ranging from 23 bars for the first, 27 bars for the second, 55 bars for the third and also 55 bars for the fourth.

The action of the water jets changes the initial position of the fibers fuses and stiff which, originally, are located perfectly in the plane of the sheet, said fibers being re-oriented along the Z axis of said sheet and their extremity rising under the effect of the knots of entanglement, or even for the longest fibers forming loops between the tangles.

The complex is then dried and subjected to treatment inside a tunnel brought to 400 ° C (the temperature of burner in the case where the fused fibers are of the polypropylene type). This heat treatment causes a partial melting of the fibers of polypropylene visible on the surface of the tablecloth making it abrasive by the formation of droplets at the point of fusion. Although the effective temperature inside the oven is 190 ° C, i.e. higher than the melting point of polypropylene, the passage speed of the sheet inside the oven is such that the fibers only melt partially, other synthetic fibers (excluding any fibers binders) entering the composition of the complex being not affected by this heat treatment, thus making it possible to preserve the flexibility of the article. As an indication, the speed of passage of the sheet at the interior of the furnace is of the order of 90 m / min, the said furnace having a "effective" length of six meters, the nonwoven being previously preheated to a temperature of 140 ° C.

Of course, these values for temperature and speed are not limiting since higher speed may be compensated by a longer useful oven length, or a higher temperature and that another type of fiber will require a adaptation of the selected temperatures.

Leaving the machine, a sheet weighing 40 g / m2 is obtained having a flexible and absorbent face and the other side of which has abrasive properties formed by the visible ends of the fibers polypropylene.

It should be noted that the choice of polyolefin fibers for constitute the scratching visible face of the article, facilitates obtaining the latter because during the suspension to form the sheet, the said fibers having a density less than 1 remain on the surface during the wet conformation.

Depending on the desired applications, this sheet can be used either as is to receive additional treatment online with a binder, in this case a polymer emulsion acrylic / vinyl acetate deposited at a rate of 10 g / m2.

The characteristics and properties of the layers obtained are grouped in the table below. WITHOUT IMPREGNATION WITH IMPREGNATION Weight (g / m2) 40.3 50.7 Thickness (microns under 100 kPa) 268 261 Permeability (L / m2 / S under 196 Pa) 1335 1103 Long-term break (N / M) 470 1439 Break through (N / M) 170 470 Elongation long direction (%) 2.5 12.3 Elongation through (%) 5.5 30.0 Wet break sense (N / M) 109 952 Wet break through (N / M) 48 286 Long direction tear (cN) 118 525 Cross tear (cN) 198 1152 Long sense stiffness (cN Handle O meter) 45 80 Cross stiffness (cN Handle O meter) 17 27 Absorption capacity (%) 693 477

Grammage : suivant méthode EDANA 40.3-90

Epaisseur : suivant méthode AFNOR NF Q 03+016

Perméabilité : suivant méthode EDANA 140.1-81

Rupture : suivant méthode EDANA 20.2 - 89 modifiée
   distance entre machoirs : 127 mm
   vitesse de traction : 25,4 mm/min

Allongement: suivant méthode EDANA 20.2 - 89 modifiée
   distance entre machoirs : 127 mm    vitesse de traction : 25,4 mm/min détection à 75 % de la rupture maximum

Rupture humide : suivant même méthode que rupture sèche mais parés séjour des bandes tests 10 min sous 20 mm d'eau distillée à 20°C

Déchirure : suivant méthode EDANA 70.3 - 96

Rigidité : avec appareillage "HANDLE-0-Meter"

Capacité d'absorption : suivant méthode EDANA 10.2 - 96.

Measurements of product characteristics are carried out under the following conditions.

Weight: according to EDANA 40.3-90 method

Thickness: according to AFNOR NF Q 03 + 016 method

Permeability: according to EDANA 140.1-81 method

Break: according to EDANA 20.2 - 89 method modified
distance between mills: 127 mm
pulling speed: 25.4 mm / min

Elongation: according to modified EDANA 20.2 - 89 method
distance between mills: 127 mm pulling speed: 25.4 mm / min detection at 75% of maximum rupture

Wet break: following the same method as dry break but trimmed test strips stay 10 min under 20 mm of distilled water at 20 ° C

Tear: according to EDANA 70.3 - 96 method

Rigidity: with "HANDLE-0-Meter" equipment

Absorption capacity: according to EDANA method 10.2 - 96.

It appears from the examples above that the non-impregnated product has a greater absorption capacity, is much more flexible, and on the other hand has relatively low mechanical characteristics which, where appropriate, could be offset by the introduction of a certain percentage of thermobonding fibers, as indicated above.

Such products are particularly suitable for carrying out semi-scouring or very absorbent wiping products, but could also be used in other areas, for example in the food industry, for solvent media, bench tops laboratories ...

• des essuyages imprégnés de liquide vaisselle pour vaisselle à usage unique (camping..),
• des essuie-mains imprégnés d'agents dégraissants et adoucissants pour travailleurs manuels (garages..),
• des essuie-vitres imprégnés d'un liquide adequat pour les véhicules (insectes écrasés, déjections d'oiseaux), le domestique .. ,
• des essuyages pour bricoleurs (nettoyage de balustrades, dépoussiérage en extérieur..).

The same product impregnated with a polymeric binder is, in turn, particularly suitable for producing:

• wipes impregnated with dishwashing liquid for disposable dishes (camping, etc.)
• hand towels impregnated with degreasing and softening agents for manual workers (garages, etc.),
• windshield wipers impregnated with a liquid suitable for vehicles (crushed insects, bird droppings), domestic ...,
• wiping for DIY enthusiasts (cleaning of railings, dusting outdoors ...).

Example 2

A complex material according to the invention is produced by combining on the one hand a nonwoven obtained by the wet method, and on the other hand, a nonwoven obtained by dry process.

The nonwoven obtained by wet process, made on the same machine than the previous example, has only one jet, forming in the final product about 50% of the total mass of the fibers.

• 33 % de fibres polypropylène, de titre 6,7 dtex, coupe 6 mm, section ronde ;
• 67 % de cellulose (pâte de bois) en fibres longues (résineux).

This sheet is obtained from a fibrous suspension comprising:

• 33% polypropylene fiber, 6.7 dtex, 6 mm cut, round section;
• 67% cellulose (wood pulp) in long fibers (resinous).

This first layer is added, before treatment by the set of fluid jets on a card web, constituting 50% of the total weight of fibers, card web made of polyester fibers having a title of 1.7 dtex, curly, and a 38 mm cut. This card veil is preferably slightly tangled with water jets beforehand ensure its cohesion and facilitate its handling.

The card web is located below the web produced humid, the whole being rewetted before being subjected to the action of entanglement jets made in the same manner as in Example 1.

After completion of the complex, the product is, as in the previous example, subjected to a heat treatment resulting in a partial melting of polypropylene fibers, making the surface where they are present abrasive.

A complex product is obtained, the characteristics of which are grouped in the table below. weight 68.4 g / m2 Thickness 255 microns at 100 kPa Permeability 1160 L / m2 / S at 196 Pa Long break 1920 N / M Break through 690 N / M Long direction elongation 29% Elongation through 30 % Long-term wet break 1600 N / M Wet break through 550 N / M Long tear 1330 cN Tear through 2810 cN Long stiffness 31 cN (Handle-O-Meter) Cross stiffness 5 cN (""") Absorption capacity 402%

Such a product which has a flexible face formed by the fibers polyester and a rough side, is particularly suitable to be used as a variety of wiping materials in a manner similar to those cited in Example 1, and which have a high flexibility amélioriée.

Of course, the invention is not limited to the examples of realization described above, but it covers all variants carried out in the same spirit.

Thus, it is possible to process the product to incorporate various additives, for example surfactants, such as alkyl -sulfonates commonly used in dishwashing liquids, these products being either added alone, or mixed with a binder. It could also be considered to add softeners, degreasers, insecticides, bactericides, flame retardants, solvents.

If polypropylene is particularly suitable for making the face scratching the article, one can also use fibers of polyethylene, or possibly other fibers such as fibers polyvinyl chloride derivatives whose melting point allows perform heat treatment without deteriorating the characteristics of fibers used in the constitution of the complex. The choice of polypropylene as a material particularly suitable for placing work of the invention, is explained by the fact, that at the date of this demand, this is the product with the best ratio price / properties (solvent resistance, stiffness, abrasiveness, skin contact and food).

Furthermore, it could possibly consider carrying out grammage products much higher than those indicated in the description above.

Finally, the ply preferably constituting the flexible layer absorbent, will consist of fibers selected according to characteristics primarily sought. As an indication, when we wish to have a flexible and highly absorbent face, we will use preferably viscose or cotton, if you are considering an item with good tear resistance, preferably use fiber polyamide and, if you want to improve the touch, you will use preferably acetate or cellulose fibers (artificial silk).

Claims (11)

1. Absorbent non-woven composite material consisting of at least two superposed fibrous sheets bonded together by interpenetration of the fibres in the thickness direction, in which:

   the first sheet consists entirely or partly of thermoplastic synthetic fibres preferably selected from the class of polyolefins;

   the second sheet, for its part, consists of natural and/or artificial and/or synthetic fibres having a higher melting point than the latter fibres;

   the individual sheets are combined by subjecting them to a treatment allowing the synthetic fibres of the first sheet to be reoriented so that, on the one hand, they are intimately bonded into the structure of the second sheet and, on the other hand, have [sic] visible loops or free ends on one of the external faces of the composite formed;

   characterized in that:

   the composite obtained is subjected to a heat treatment to melt the free ends of the synthetic fibres of the first sheet, making the latter abrasive by the formation of droplets at the place of the melting.
2. Material according to Claim 1, characterized in that the first sheet consists of a mixture of cellulose or other fibres and of thermoplastic synthetic fibres, the percentage of the latter fibres in the sheet being greater than 30% and preferably greater than 50%.
3. Material according to either of Claims 1 and 2, characterized in that the synthetic fibres used in making up the first sheet are polypropylene or polyethylene fibres.
4. Material according to Claim 3, characterized in that the fibres have a linear density of greater than 5 dtex for a length of greater than 5 mm.
5. Material according to one of Claims 1 to 4, characterized in that the natural and/or artificial fibres allowing the absorbent character to be obtained are paper-making fibres, viscose fibres, etc.
6. Material according to one of Claims 1 to 5, characterized in that the synthetic fibres used in making up the second sheet are polyester or polyamide fibres, optionally crimped, having a melting point above those used in making up the first sheet.
7. Material according to one of Claims 1 to 6, characterized in that the composite undergoes an additional treatment, such as creping, treatment with wetting agents making it possible to improve its hydrophilicity and the impregnation with a relatively aggressive liquid, such as a washing-up liquid.
8. Material according to one of Claims 1 to 7, characterized in that the grammage of the second sheet is between 15 and 200 g/m² and that of the first sheet is between 10 and 70 g/m².
9. Process for obtaining a material according to one of Claims 1 to 8, characterized in that two sheets of individual fibres are produced, the two sheets being bonded together downstream of the formation zone by a needle-punching treatment using fluid jets acting at least against the surface of the first sheet, characterized in that the non-woven composite formed is then dried and receives a complementary heat treatment for causing the partial melting of the ends of the chemical fibres of the first layer which remain bonded to the non-woven base composite.
10. Process according to Claim 9, characterized in that the two individual layers are produced by the wet route, with these being combined on the dewatering belt before treatment using fluid jets.
11. Process according to Claim 9, characterized in that the second sheet is obtained by the technique called the "dry route", the two individual sheets being combined after the formation of this sheet by the dry route, by attaching, to its surface, on that side where the action of the interlacing fluid jets will be exerted, the first web produced by the wet route, the two superposed sheets being preferably rehumidified before they undergo the action of the entangling jets.