EP1117860B1 - Method for producing a complex nonwoven material and resulting novel material - Google Patents

Abstract

The invention concerns a method which consists in continuously: producing by carding (1) a web (10 from chemical fibers; subjecting the resulting web (1) to a hydro-entanglement using water jets, treatment which consists in: (a) consolidating the web (10) by the action of a first series of water jets (3), the web (10) being supported by a drum (4) comprising micro-perforations; (b) subjecting the consolidated web (10) to structuring, by the action of one or several series of water jets (12); depositing on the surface of the resulting structured lap (10a) natural fibers (14) by pneumatic layering (6); subjecting the resulting complex (20) to the action of another series of water jets (7) acting on the surface covered with natural fibers.

Description

Technical area

For decades, it has been proposed to replace textile tablecloths traditional (fabric, knitting) by so-called "non-woven" structures which, in a general can be classified into three broad categories, resulting from their the manufacturing process itself, namely the so-called "dry" nonwovens, "by melted ", and nonwovens said" wet ".

The present invention relates to a new type of material obtained according to the first technique cited, namely, "dry process".

In general, to produce such nonwovens, we form, from staple fibers, natural or chemical, by card or the like textile preparation material, a veil of fibers of predetermined grammage, which we then submit to a processing allowing it to communicate the appropriate mechanical characteristics depending on the uses to which it is intended for the product, for example a mechanical needling treatment or interlacing by fluid jets.

Furthermore, it has been known for a very long time that it is possible to adapt the final properties of the product obtained by making mixtures of materials, by example by combining together several sails made of natural fibers different, for example, from natural, artificial or synthetic fibers.

The invention relates to a new method for carrying out such a type non-woven article made from a mixture of fibers of a different nature and which, in the rest of the description will be denoted by the expression "mixed fleece".

Previous techniques

Many proposals have been made to date to make nonwovens mixed and more particularly of nonwovens associating between them a veil of artificial or synthetic fibers and a veil of cellulosic fibers, especially wood fibers.

The association of the various constituents with one another is advantageously obtained by hydraulic entanglement of fibers, a technique that has been known for a long time long and described in particular in US Patents 3,033,721, 3,214,819 and 3,508 308.

After having made a first veil, a layer of cellulosic fibers, wood fibers in particular, of appreciably grammage equivalent to that of artificial or synthetic fibers, said fibers cellulosics then being entangled with the chemical fibers also by a treatment with water jets. The product obtained has good mechanical strength characteristics, these characteristics being essentially brought by synthetic fibers as well as good characteristics absorption, these being imparted by the cellulosic fibers.

Such products are used in particular for making "wipes wet "designated in this technical sector by the English expression" baby wipes ", as well as hygiene, and also as cloths wiping.

This type of mixed nonwoven is increasingly tending to replace nonwovens traditional compounds of mixture of synthetic fibers (polyester, polypropylene) and artificial fibers (viscose), mainly because of its price lower cost, wood fibers costing three to four times less than viscose fibers.

In the current state of the art, as described above, a product with satisfactory resistance and absorption characteristics but whose appearance and textile feel are unfortunately lower compared to to traditional nonwovens made from artificial and synthetic fibers.

This is due to the fact that the veil is asymmetrical in thickness, the fibers artificial and synthetic being arranged on one side of the veil and the natural fibers on the other side.

In order to overcome this defect, devices such as spraying on the natural fibers of chemical softening agents but that does not make disappear completely the fault.

Another negative aspect of this type of item is the abrasion resistance of the veil which is very inferior on the side of natural fibers; this results in wiping operations for fiber losses (salting out) which in many cases are considered essential for the use made of it.

Consequently, in order to overcome this defect, it has been proposed to introduce fibers natural "sandwich" between two layers of artificial or synthetic fibers. This solution is not satisfactory both technically and technically economical for the following reasons.

Indeed, the fact of halving the grammage of the layers of artificial and / or synthetic fibers makes it very difficult to hydraulically bond these layers. For example, in the case of a 50 g / m ^{2 product} comprising 50% natural fibers (i.e. 25 g / m ² ) and 50% synthetic fibers in two layers, i.e. 12.5 g / m ² per layer , it is extremely difficult if not impossible to bond these layers with water jets.

Furthermore, the too low grammage of the first support layer does not allow not for it to act as a filtering medium for natural fibers during their deposit then of their interlacing with water jets. This results in a loss in considerable fibers, these being driven through the support fabric by the jets of water, this loss in fibers considerably reduces the economic interest of process.

Statement of the invention

The present invention aims to overcome the problems and drawbacks mentioned above, and to allow the production of an absorbent nonwoven, containing a large amount of natural fibers (wood pulp) with excellent physical properties (tensile strength, tear strength, abrasion) good absorption capacities and moreover having a touch pleasant similar to that of products made from artificial fibers and / or synthetic.

• à réaliser par cardage ou autre technique conventionnelle un premier voile à partir de fibres chimiques (artificielles et/ou synthétiques) ;
• à soumettre ledit voile ainsi formé à un traitement de liage au moyen de jets d'eau, traitement consistant :
  • dans une première phase : à consolider le voile par action d'une première série de jets d'eau agissant sur l'une de ses faces, le voile étant supporté par un tambour comportant des micros perforations ;
  • dans une seconde phase : à structurer le voile ainsi consolidé au moyen d'un cylindre ou sur un convoyeur revêtus d'une toile grossière, par action d'une ou plusieurs séries de jets d'eau ;
• à déposer à la surface de la nappe ainsi structurée des fibres naturelles (fibres de bois) par nappage pneumatique ;
• à soumettre le complexe ainsi formé à l'action d'une nouvelle série de jets d'eau agissant sur la face recouverte de fibres naturelles ;
• à procéder à un traitement de séchage, puis à réceptionner le produit fini sous la forme d'un enroulement.

In general, the invention therefore relates to a process allowing the production of a new type of nonwoven consisting of a mixture of elementary fibers of different nature which consists, continuously:

• to make by carding or other conventional technique a first veil from chemical fibers (artificial and / or synthetic);
• subjecting said veil thus formed to a binding treatment by means of water jets, treatment consisting of:
  • in a first phase: to consolidate the veil by action of a first series of water jets acting on one of its faces, the veil being supported by a drum comprising micro perforations;
  • in a second phase: to structure the veil thus consolidated by means of a cylinder or on a conveyor coated with a coarse canvas, by the action of one or more series of water jets;
• depositing natural fibers (wood fibers) on the surface of the sheet thus structured by pneumatic coating;
• subjecting the complex thus formed to the action of a new series of water jets acting on the face covered with natural fibers;
• to carry out a drying treatment, then to receive the finished product in the form of a coil.

For the implementation of the method according to the invention, the first treatment with water jets will be carried out in accordance with the teachings of FR-A-2 730 246 and FR-A-2 734 285.

The second treatment by water jets allowing the structuring of the sheet of fibers synthetic and / or artificial, is, meanwhile, made using as canvas coarse supporting the veil an openwork conveyor of the type as described in the FR-A-2 741 895.

In accordance with the process according to the invention, the distribution of the fibers cellulosic (wood fibers) on the surface of the veil of synthetic fibers can be performed both on the face which has been subjected to the action of the jets allowing the structuring of said sheet only on the reverse side.

Furthermore, the structuring treatment can be obtained both in causing the second series of jets to act on the same face which received the impact of the jets performing the consolidation action only on the opposite side thereof.

The invention also relates to a new type of nonwoven product obtained. in particular by the implementation of this process.

Such a mixed nonwoven which consists of a mixture of natural fibers different, is characterized in that it consists of a tablecloth made from chemical fibers (artificial and / or synthetic) which has received a binding treatment and reorientation of the fibers by means of water jets making it possible to have zones alternating porosities, natural fibers, wood in particular, being distributed preferentially inside areas of high porosity, cohesion of the assembly being also obtained by entanglement thanks to the action of jets of water.

Brief description of the drawings

• la figure 1 est une vue schématique d'un ensemble d'une ligne de production d'un matériau complexe conforme à l'invention, les figures la, 1b, 1c étant des vues agrandies des zones cerclées de cette figure 1 ;
• la figure 2 est une vue schématique, fortement agrandie, montrant la structure de la première nappe à base de fibres chimiques après traitement de consolidation et structuration du voile ;
• la figure 3 est une vue agrandie schématique du complexe mixte réalisé conformément à l'invention et,
• la figure 4 est une vue schématique d'une variante d'une ligne de production d'un matériau conforme à l'invention.

The invention and the advantages which emerge therefrom will be better understood thanks to the examples of embodiments which follow given by way of non-limiting example, and which is illustrated by the appended diagrams in which:

• Figure 1 is a schematic view of an assembly of a production line for a complex material according to the invention, Figures la, 1b, 1c being enlarged views of the circled areas of this Figure 1;
• Figure 2 is a schematic view, greatly enlarged, showing the structure of the first sheet based on chemical fibers after consolidation treatment and structuring of the web;
• FIG. 3 is an enlarged schematic view of the mixed complex produced in accordance with the invention and,
• Figure 4 is a schematic view of a variant of a production line for a material according to the invention.

Way of realizing the invention

Referring to the attached diagrams and more particularly to Figures 1a and 1c, a nonwoven made of a mixture of elementary fibers of different nature in the following way.

On a production line allowing the various operations to be carried out continuously, we perform by carding or other similar technique (area referenced there Figure 1) a first veil (10) from artificial or synthetic fibers.

This veil (10) is then brought to a set of treatments (2) allowing to carry out its binding by means of water jets.

This binding treatment consists, in a first phase, of consolidating the veil by the action of a first series of water jets (3) acting on one of the faces of said veil, this being supported by a drum (4) comprising microphones perforations.

Such a binding assembly can be carried out in accordance with lessons from FR-A-2 730 246 and FR-A-2 734 285.

After consolidation, the web (10) is transferred to a treatment unit (5) constituted either by a second perforated cylinder (25) or by an openwork conveyor allowing a structuring of the formed web.

To do this, the conveyor or the surface of the second cylinder is formed by a coarse cloth of the type described in FR-A-2,741,895.

At this level, as can be seen from FIG. 1a, the fibrous web (10) supported by the coarse fabric (11) is subjected to the action of water jets (12) which have an action such that the fibers of the web (10) are separated from each other by said jets at the crossing point of the strands of the fabric (11), which causes the formation of a veil (10a) having a three-dimensional organization of the fibers with areas of variable density where the structure of such a restructured sail is illustrated by FIG. 2, it can therefore be said that such a veil has zones (22) to high density of fibers separated from each other by zones (21) with low fiber density.

The structured veil (10a) is then brought to an assembly (6) making it possible to distributing on its surface fibers (14) of another kind and more particularly cellulosic fibers (wood).

Such an assembly (6) makes it possible to deposit said fibers by the technique known as "pneumatic covering", the web (10a) (see FIG. 2a) being maintained on a conveyor belt (13) subjected to a suction, the fibers natural, wood fibers, more particularly (14) being projected onto the surface of the veil (10a) via an air stream. Under the effect of suction, said fibers therefore tend to settle in areas with the most porosity high, that is to say in the area (21) of FIG. (2) making it possible to form a complex as illustrated in FIG. 3 in which the natural fibers - fibers of wood - are deposited between artificial and synthetic fibers.

The complex (20a) thus produced is then transferred to an assembly (7) allowing to carry out a tangle treatment by water jets as illustrated in Figure 1c.

The mixed nonwoven obtained is then dried in (8) before being rolled up. conventional way in (9).

Figure 4 illustrates a variant according to the invention which differs from that illustrated in Figure 1 by the way in which the structuring operation of the sheet after the first treatment with jets of fluid in (4).

Indeed, in such a case, the operation of structuring by jets is carried out in causing the jets to act on the same face as that which had been previously treated.

Thanks to such a process, mixed complexes are obtained in which there are excellent interpenetration of different natural, artificial and synthetic to avoid the double-sided aspect of previous techniques.

Example

A product according to the invention is produced in the following manner.

A veil of 30 g / m ² composed of 40% viscose fibers of 38 mm and 1.7 dtex and 60% of polyester fibers of 38 mm and 1.7 dtex is produced on a "random" type card at the speed of 110 m / min.

This veil is introduced on a hydraulic binding unit "Jetlace 2000" by the through a transport conveyor.

The veil is compacted between this conveyor and a first binding cylinder coated with a micro-perforated envelope, the holes being arranged randomly as described in French patent 2,734,285. After compaction, the veil is pre-wetted via a ramp located behind the conveyor transport, just after the compaction point and arranged perpendicular to the generator of the cylinder.

The veil thus compacted and wet is then subjected to the action of two hydraulic injectors projecting 120 micron diameter water jets at increasing speeds of 90 and 110 m / second, the water jets being spaced apart others 1.2 mm.

The veil is then introduced on a conveyor equipped with a canvas consisting of 8.7 threads per cm of polyester 0.50 mm in diameter in the warp direction and 9.4 son / cm in stainless steel 0.38 mm in diameter in the weft direction.

Two hydraulic injectors are arranged above this conveyor. They project 120 micron diameter water jets at speeds of 100 m / second, the jets being spaced from each other by 0.5 mm.

The veil is then expressed using a suction box connected to a generator empty.

The product leaving this conveyor has an embossed type appearance. pyramidal with areas of different fiber density.

The veil is then introduced on a pneumatic lapping machine, which deposits 30 g / m ² of cellulose fibers.

After depositing these fibers, the veil is introduced on another conveyor above of which are arranged four hydraulic injectors projecting water jets of 120 microns in diameter spaced from each other by 0.6 mm at speeds of 114 m / second.

The veil is then expressed by a suction box connected to a generator. vacuum then dried by air cylinder through at a temperature of 120 ° C then wound.

It is found that the product thus obtained has excellent homogeneity, far superior to that of a similar but "unstructured" product.

Besides, the touch of the product is excellent, it is particularly difficult to identify the respective faces (synthetic and cellulosic sides) finally the abrasion resistance in both dry and wet conditions is considerably improved, which results in an absence of release of natural fibers.

Claims (6)

1. A process for the production of a nonwoven consisting of a mixture of elementary fibers of different nature, which consists in continuously:

   producing, by carding (1) or another conventional technique, a first web (10) from chemical fibers;

   subjecting the web (10) thus formed to a bonding treatment by means of water jets, said treatment consisting:

   in a first step: in consolidating the web (10) by the action of a first series of water jets (3) acting on one of its faces, the web (10) being supported by a drum (4) having microperforations;

   in a second step: in structuring the web (10) thus consolidated by means of a suction roll or on a conveyor, the roll or conveyor being covered with a coarse fabric (13), by the action of one or more series of water jets (12);

   depositing, on the surface of the lap (10a) thus structured, natural fibers (14) by pneumatic layering (6);

   subjecting the complex (20) thus formed to the action of a new series of water jets (7) acting on the face covered with natural fibers;

   carrying out a drying treatment (8) and then collecting the end product in the form of a wound reel.
2. The process as claimed in claim 1, characterized in that the cellulose fibers (wood fibers) (14) are distributed over the surface of the web (10a) of synthetic fibers on that face which has been subjected to the action of the jets allowing said lap to be structured.
3. The process as claimed in claim 1, characterized in that the cellulose fibers (wood fibers) (14) are distributed over the surface of the web (10a) of synthetic fibers on the opposite face to that which has been subjected to the action of the jets allowing said lap to be structured.
4. The process as claimed in one of claims 1 to 3, characterized in that the structuring treatment (5) is carried out by making the second series of jets (12) act on the same face of the web that has received the impact of the jets (3) producing the consolidation action.
5. The process as claimed in one of claims 1 to 3, characterized in that the structuring treatment (5) is carried out by making the second series of jets act on the opposite face of the web to that which has received the impact of the jets producing the consolidation action.
6. A nonwoven obtained especially by implementing the process as claimed in one of claims 1 to 5, consisting of a mixture of fibers of different nature, characterized in that it is composed of a lap produced from chemical (artificial and/or synthetic) fibers which has received a treatment for bonding and reorienting the fibers by means of water jets, making it possible to have alternating regions of different porosity, natural, especially wood, fibers being preferably distributed within the regions of high porosity and the cohesion of the assembly also being obtained by entanglement due to the action of water jets.

Images