EP0177425B1 - Non-woven long-fibre sheet product and process for its manufacture - Google Patents

Abstract

1. Method for manufacturing a suspension of long fibres usable in a paper machine, these fibres having a length of at least 12-18-24-30 or 34 mm respectively for sizes of 1.7-3.3-4.4-6.7 or 11 decitex, characterized in that it comprises the following steps : a) in a first water dose, a first dose of first greased long fibres is suspended and a first dose of a first polyelectrolyte having a high molecular weight and the same ionic character as the hydrated greasing of said first fibres is added thereto, the weight proportion of said first polyelectrolyte being comprised between 0,2 and 0,5 % of the weight of said first fibres ; b) after stabilization of the suspension formed under a), a second water dose is added thereto and then a second dose of second long fibres, the hydrated greasing of which has the same ionic character as that of said first fibres, as well as a second dose of a second polyelectrolyte having a high molecular weight and the same ionic character as the hydrated greasing of said second fibres, the cumulated weight proportion of the first and second polyelectrolytes with respect to the cumulated weight of said first and second fibres remaining within the same range as that of said first polyelectrolyte with respect to said first fibres ; c) the manufacturing of said suspension of long fibres is carried on up to the nths adding to the cumulated suspension containing the (n-1)th first fibres, a nth water dose and then a nth dose of nth long fibres, the hydrated greasing of which has the same ionic character as that of the (n-1)th fibres, as well as a nth dose of a nth polyelectrolyte having a high molecular weight and the same ionic character as the hydrated greasing of said (n-1)th fibres, the cumulated weight proportion of the n polyelectrolytes with respect to the cumulated weight of said n fibres remaining within the same range as that of the first polyelectrolyte with respect to said first fibres.

Description

The present invention relates to nonwoven sheet products with long fibers and their manufacturing process by papermaking.

Although not exclusively, the present invention is particularly suitable for producing a dimensionally stable composite sheet capable of exhibiting very high resistance to punching, which can be impregnated, either with bitumen or the like, for example for use in waterproofing. of buildings (in particular of the roofs thereof), or of a resin serving as reinforcement for dimensional stabilization.

• - une bonne stabilité dimensionnelle;
• - une bonne résistance au vieillissement;
• - une bonne résistance aux agents atmosphériques, aux produits chimiques, aux chocs thermiques, aux variations hygrothermiques du support sur lequel ils sont disposés, etc....;
• - une bonne résistance au poinçonnement, notamment si des hommes et du matériel doivent circuler sur lesdits produits, après leur pose;
• - une bonne résistance à l'abrasion; et
• - une bonne aptitude à l'imprégnation par le bitume, les élastomères, etc... en vue de permettre de les rendre étanches.

It is known that fibrous composite products in sheet form, intended for the production of seals in the building industry, must have the following properties:

• - good dimensional stability;
• - good resistance to aging;
• - good resistance to atmospheric agents, chemicals, thermal shock, hygrothermal variations of the support on which they are placed, etc ...;
• - good resistance to punching, in particular if men and equipment must circulate on said products, after their installation;
• - good resistance to abrasion; and
• - a good ability to impregnate with bitumen, elastomers, etc. in order to make them waterproof.

Such properties are sometimes contradictory and cannot be obtained using only one kind of fiber. It is therefore necessary to use several different kinds of fibers, which may also have different lengths and / or diameters. For example, resistance to aging and dimensional stability are provided by long glass fibers, while resistance to punching is obtained by polyester fibers also of great length.

Currently, such a product is for example produced by the superposition of a veil of glass fibers and a veil of polyester fibers, assembled to one another (lamination) and impregnated with bitumen, a resin or the like.

However, such a known product does not allow optimum properties to be obtained. Indeed, in order to give the glass veil sufficient mechanical strength, allowing complexing, it is necessary that said glass veil has a thickness which is greater than the thickness which would correspond to the desired proportion of glass fibers in the product. finished; it follows that the latter is too rigid and does not withstand either the impact constraints or the dimensional variation constraints of its support. Furthermore, the veil of polyester fibers is produced, in a known manner, by the continuous melt method, so that the polyester fibers are only partially drawn and that their length is not stabilized: it follows that the finished product is less dimensionally stable than it should be.

• - realiser un produit fibreux en feuille stable dimensionnellement et thermiquement susceptible d'être imprégné et formant une feuille composite dans laquelle des fibres de natures, longueurs et/ou diamètres différents sont intimement mêlées, afin de permettre l'obtention de meilleures propriétés pour le produit fini et l'éventuelle incorporation de charges, inertes ou susceptibles de conférer d'autres propriétés au produit fini;
• - réduire à la quantité juste suffisante la proportion des fibres de verre ou analogues, afin d'améliorer la résistance du produit fini aux contraintes de chocs et de variations dimensionnelles;
• - permettre l'utilisation de fibres de polyester ou analogues de grande longueur étirées jusqu'à leur stabilisation dimensionnelle, afin d'améliorer la stabilité dimensionnelle du produit fini.

The object of the present invention is to remedy these drawbacks. Some of its main objectives are therefore:

• - produce a fibrous product in a dimensionally stable and thermally stable sheet capable of being impregnated and forming a composite sheet in which fibers of different natures, lengths and / or diameters are intimately mixed, in order to allow better properties for the product to be obtained finish and the possible incorporation of fillers, inert or capable of imparting other properties to the finished product;
• - Reduce to the just sufficient amount the proportion of glass fibers or the like, in order to improve the resistance of the finished product to the constraints of impact and dimensional variations;
• - allow the use of polyester fibers or the like of very long stretched until their dimensional stabilization, in order to improve the dimensional stability of the finished product.

To achieve these objectives, it would be advantageous to be able to implement the process for manufacturing non-woven fibrous products by the wet process on a paper machine; however, this has so far proved impossible.

It is known in fact that in order to manufacture nonwoven products by the wet process, one begins by dispersing fibers in water by means of a pulper, then the suspension obtained is stored in a vat intended to keep it homogeneous and provided with this effect of a stirring propeller. Such a vat serves as a flywheel to supply a hydroformer, on the inclined canvas from which the veil of nonwoven material is formed. Thus, this wet technique of manufacturing nonwoven products is modeled on the technique of making papers.

However, if the use of paper fibers, relatively short, dispersed and suspended in this way, does not raise difficulties, it is not the same for artificial and synthetic fibers of great length.

Indeed, the stirring of the fibers, necessary for the dispersion of these and for the homogenization of the suspension, generates agglomerations of fibers beyond certain thresholds of length of said fibers. The suspension in the pulper and the storage in the vat therefore limit the usable length of the fibers. For example, the length of the fibers that can be used is thus limited to 6 mm for a titer of 1.7 decitex and to 10 - 15 mm for fibers of higher titer, at the usual concentrations of 0.5 to 1% of feeding of the hydroformer.

Generally, these artificial and synthetic fibers used are cut to length in "cables" and the sections of cables thus cut form small compact bundles of fibers bonded by the sizes required for manufacture of these cables. After introduction into the water and under the effect of stirring, the bundles come apart, but at the same time, the released fibers are knotted together, all the more quickly the longer they are and the more size is less stable, in particular due to the addition of peptizing agents, surfactants, wetting agents and

dispersants.

To avoid certain effects of these sizes, we already know solutions of sizing intended to prepreg the fiber bundles before their introduction into the pulper. Generally, the fiber bundles, pretreated in such a desensing solution, open completely within 10 to 15 seconds. However, in the case of long fibers, such sizing solutions do not prevent the re-agglomeration of the fibers, especially since certain fibers, such as for example glass or polyester fibers, have a tendency to agglomerate by mutual attraction. Such fibers, after dispersion, do not knot, but agglomerate into bundles of adjoining fibers.

To overcome this drawback, it has already been proposed to add polyelectrolytes to the dispersion liquid, making it possible to electrically charge the fibers as they leave the fibrous bundles during the dispersion, so that they do not are more likely to attract each other after separation.

In some cases, to avoid re-agglomeration of the dispersed fibers, it has also been proposed to increase the viscosity of the liquid mass of the disperser either by adding a thickener or by introducing air into this liquid.

It has also been noted that if fiber bundles to be dispersed are introduced into a medium which already contains long dispersed fibers, the dispersion of said beams is hampered, all the more since the fibers already dispersed are all the more long. On the other hand, if the medium contains short fibers already dispersed such as certain paper fibers for example, the dispersion of the bundles of long fibers can be favored.

However, these observations and proposals result from laboratory experiments and are not sufficient in themselves to solve the difficulties mentioned above and to make it possible to produce industrially, by the papermaking route, nonwoven products with long fibers.

• - une feuille de produit non tissé, contenant des fibres longues cellulosiques, synthétiques, minérales, etc..., stable dimensionnellement et thermiquement, obtenue industriellement par voie papetière;
• - la réalisation industrielle d'une telle feuille sur une machine connue de fabrication d'un produit non tissé par voie papetière, avec des fibres de différentes longueurs et/ou de différents diamètres;
• - la préparation, en vue de son utilisation sur machine à papier, d'une suspension aqueuse de fibres de longueurs et/ou de diamètres

In view of the above, other objectives of the present invention are therefore, from the known elements of the prior art recalled above:

• - a sheet of non-woven product, containing long cellulosic, synthetic, mineral fibers, etc., dimensionally and thermally stable, obtained industrially by the papermaking process;
• - the industrial production of such a sheet on a known machine for manufacturing a nonwoven product by the papermaking route, with fibers of different lengths and / or of different diameters;
• - the preparation, for use on a paper machine, of an aqueous suspension of fibers of lengths and / or diameters

different.

• - 12 mm pour un titre de 1,7 décitex
• - 18 mm pour un titre de 3,3 décitex
• - 24 mm pour un titre de 4,4 décitex
• - 30 mm pour un titre de 6,7 décitex
• - 34 mm pour un titre de 11 décitex.

By long fibers is meant in the present description fibers whose length is greater than 6 mm for a titre of 1.7 decitex and 15 mm for greater titles. By way of example, the present invention makes it possible to manufacture nonwoven products by the papermaking route from fibers whose length is at least equal to:

• - 12 mm for a title of 1.7 decitex
• - 18 mm for a title of 3.3 decitex
• - 24 mm for a title of 4.4 decitex
• - 30 mm for a title of 6.7 decitex
• - 34 mm for a title of 11 decitex.

In addition, the invention makes it possible to use such fibers for weight proportions of at least 50% of the finished dry product.

• a) dans une première dose d'eau, on met en suspension une première dose de premières fibres longues ensimées et on y ajoute une première dose d'un premier polyélectrolyte à haut poids moléculaire de même caractère ionique que l'ensimage hydraté desdites premières fibres, la proportion pondérale dudit premier polyélectrolyte étant comprise entre 0,2 et 5 % du poids desdites premières fibres;
• b) après stabilisation de la suspension produite sous a), on ajoute à celle-ci une seconde dose d'eau, puis une seconde dose de secondes fibres longues, dont l'ensimage hydraté a le même caractère ionique que celui desdites premières fibres, ainsi qu'une seconde dose d'un second polyélectrolyte à haut poids moléculaire de même caractère ionique que l'ensimage hydraté desdites secondes fibres, la proportion pondérale cumulée du premier et du second polyélectrolytes par rapport au poids cumulé desdites premières et secondes fibres restant dans la même fourchette que celle du premier polyélectrolyte par rapport auxdites premières fibres;
• c) on poursuit l'élaboration de ladite suspension de fibres longues jusqu'aux nièmes fibres en ajoutant à la suspension cumulée contenant les n-1 )ièmes premières fibres, une nième dose d'eau, puis une nième dose de nièmes fibres longues, dont l'ensimage hydraté a le même caractère ionique que celui des (n-1)ièmes fibres, ainsi qu'une nième dose d'un nième polyélectrolytes à haut poids moléculaire de même caractère ionique que l'ensimage hydraté desdites (n-1 )ièmes fibres, la proportion pondérale cumulée des n polyélectrolytes par rapport au poids cumulé desdites n fibres resant dans la même fourchette que celle du premier polyélectrolyte par rapport auxdites premières fibres.

For these purposes, according to the invention, the process for producing a suspension of long fibers usable on a paper machine, these fibers having a length of at least 12-18-24-30 or 34 mm respectively for 1.7 - 3.3 - 4.4 - 6.7 or 11 decitex is characterized in that it operates as follows:

• a) in a first dose of water, a first dose of first sized long fibers is suspended and a first dose of a first high molecular weight polyelectrolyte of the same ionic character as the hydrated size of said first fibers is added thereto , the proportion by weight of said first polyelectrolyte being between 0.2 and 5% of the weight of said first fibers;
• b) after stabilization of the suspension produced under a), a second dose of water is added thereto, then a second dose of second long fibers, the hydrated size of which has the same ionic character as that of said first fibers, as well as a second dose of a second high molecular weight polyelectrolyte of the same ionic character as the hydrated size of said second fibers, the cumulative weight proportion of the first and second polyelectrolytes relative to the cumulative weight of said first and second fibers remaining in the same range as that of the first polyelectrolyte relative to said first fibers;
• c) the elaboration of said suspension of long fibers is continued up to the nth fibers by adding to the cumulative suspension containing the n-1) ith first fibers, an nth dose of water, then an nth dose of nth long fibers, whose hydrated size has the same ionic character as that of the (n-1) th fibers, as well as an n th dose of an n th high molecular weight polyelectrolyte of the same ionic character as the hydrated size of said (n-1) th fibers, the cumulative weight proportion of the n polyelectrolytes relative to the cumulative weight of said n fibers residing in the same range as that of the first polyelectrolyte relative to said first fibers.

• A) On commence par réaliser une bouillie de fibres cellulosiques, dont la concentration pondérale en fibres est comprise entre 2,5 et 4 % et dont l'indice de gouttage est compris entre environ 10 et 60 degrés Shopper;
• B) On réalise par ailleurs une suspension de fibres longues en opérant de la façon décrite ci-dessus; puis
• C) On incorpore ladite bouillie de fibres cellulosiques à ladite suspension des n fibres longues et on alimente une machine papetière avec le mélange résultant de l'incorporation.

In addition, according to the invention, the process for the industrial production by papermaking of a sheet nonwoven product based on sized long fibers, these fibers having a length of at least 12 - 18 - 24 - 30 or 34 mm respectively for titles of 1.7 - 3.3 - 4.4 - 6.7 or 11 decitex is characterized in that:

• A) We start by making a slurry of cellulosic fibers, the fiber weight concentration of which is between 2.5 and 4% and whose drop index is between approximately 10 and 60 degrees Shopper;
• B) A suspension of long fibers is also produced by operating in the manner described above; then
• C) Incorporating said slurry of cellulosic fibers into said suspension of n long fibers and feeding a papermaking machine with the mixture resulting from the incorporation.

Thus, thanks to the present invention, the degree of bursting of the long fiber bundles is controlled and they can be kept in a controlled open position for a sufficiently long time, which corresponds to that which flows between the suspending the fibers in preparation and introducing them into the paper machine.

In fact, when the bundles of long fibers are introduced into the water, their size becomes hydrated and generates ionic forces allowing their division down to the elementary fibers. If this water contains a polyelectrolyte with the same electrical charge as the hydrated size, a force field is created within the liquid, the intensity of which depends on the proportion of said polyelectrolyte. By choosing this proportion adequately, we can therefore ensure that there is a balance between the ionic forces of division due to the hydrated size and the forces due to the polyelectrolyte, the beams are then divided into fibers, while avoiding their re-agglomeration. It is then possible, by determining the appropriate proportion of the polyelectrolyte, to maintain the balance of forces until introduction into the paper machine.

By operating in accordance with the invention, dose of long fibers after dose of long fibers, the bundles of each dose of fibers (except for the first) disperse in a liquid medium already containing fibers dispersed in equilibrium. This results in a cumulative synergistic effect, favored by the fact that the supply of a new dose of polyelectrolyte keeps the content thereof constant. Thanks to the process according to the invention in cumulative stages, it is possible to obtain, in the suspension, a concentration of dispersed fibers much greater than that which it would be possible to obtain by introducing all the long fibers at once. Then, the addition of the cellulose fiber slurry makes it possible to maintain the dispersion of the long fibers up to the paper machine.

It will be noted that, in the implementation of the invention, the size of the fibers is very important, since it determines the choice of high molecular weight polyelectrolytes to be used according to the types of size, these polyelectrolytes should be chosen from anionic or cationic type.

The long sized fibers used in the plurality of operations a), b) and c) of step B of the process according to the invention can be of different types, lengths and diameters. They can also be of the same nature, but of different lengths and diameters.

Likewise, the n polyelectrolytes used in this plurality of operations may be different; however, it is advantageous that the doses of polyelectrolytes necessary for the preparation of the suspension of long fibers consist of the same product.

• - resine polyacrylamide
• - resine polyamidamine
• - résine polyamine (I)
• - résine carboxyvinylique
• - résine polyéthylènamine
• - résine polyéthylènamine modifiée.

In the most frequent case where the hydrated size of the long fibers used is of the anionic type, the anionic polyelectrolyte (s) of high molecular weight used in operations a), b) and c) of step B can be chosen from the substances gathered in list 1 below:

• - polyacrylamide resin
• - polyamidamine resin
• - polyamine resin (I)
• - carboxyvinyl resin
• - polyethylene resin
• - modified polyethylene resin.

Advantageously, short fibers of different natures, synthetic or mineral, can be mixed with the cellulosic fibers of said slurry.

In addition, in known manner, this porridge can undergo a known treatment based on

polyelectrolytes.

• - sulfate d'aluminium
• - polychlorure d'aluminium
• - aluminate de sodium et de calcium
• - polyéthylènamine (II)
• - résine polyamide épichlorydrine
• - résine polyamide amine
• - résine aminoplaste
• - résine phénoplaste
• - fécule
• - amidon carboxyméthyle
• - polysaccharide
• - galactomane
• - hydrochlorure.

For example, it is usual to treat a cellulose slurry with the cationic products listed in list II below:

• - aluminum sulfate
• - aluminum polychloride
• - sodium and calcium aluminate
• - polyethylenamine (II)
• - polyamide epichlorohydrin resin
• - amine polyamide resin
• - aminoplast resin
• - phenoplast resin
• - starch
• - carboxymethyl starch
• - polysaccharide
• - galactomane
• - hydrochloride.

• - carboxyméthylcellulose
• - gélatine
• - méthyléthylcellulose
• - alcool polyvinylique
• - alginate
• - dextrine (III)
• - monogalactane
• - polysaccharide
• - resine carboxyvinylique
• - copolymère d'acrylate
• - latex synthétique.

Likewise, it is usual to treat a cellulose slurry with the anionic products stated in list III below:

• - carboxymethylcellulose
• - gelatin
• - methylethylcellulose
• - polyvinyl alcohol
• - alginate
• - dextrin (III)
• - monogalactan
• - polysaccharide
• - carboxyvinyl resin
• - acrylate copolymer
• - synthetic latex.

In the case where the slurry of cellulosic fibers, optionally added with other mineral or synthetic fibers, undergoes such a treatment, it is advantageous that at least one polyelectrolyte of said treatment is the same as the high molecular weight polyelectrolyte used in the n operations of step B) of preparation of the suspension of long fibers.

Preferably, the long fibers are incorporated into said suspension in decreasing order of difficulties in setting and maintaining suspension: for equal or close, the fibers are introduced successively with decreasing lengths, and at equal or close length, by title croissant.

After successive incorporation of long fibers into said suspension, shorter fibers, for example of different natures, can be added to it.

Thus, the present invention relates to a sheet nonwoven product obtained industrially by the papermaking process and comprising cellulosic fibers. This product is remarkable in that it comprises mineral or organic fibers whose length is at least 12 - 18 - 24 - 30 or 34 mm respectively for titles of 1.7 - 3.3 - 4.4 - 6 , 7 or 11 decitex, these long fibers representing at least 30% of the dry weight of said product.

Such a product can then have high properties of resistance to punching, impact and tearing, while undergoing significant elongations.

Indeed, for this, it is sufficient to provide fibers of high titer to provide the resistance to punching and tearing, and fibers of lower titer to give point resistance and cohesion.

Optionally, such a product can undergo a reinforcing surface treatment.

• - synthétiques: de types polyamide, polyester, acrylique, céramique, etc...
• - cellulosiques de type acétate, triacétate, viscose, etc.
• - minérales verre, laine de roche, carbone, bore, mallastonite, métallique, etc.

It can incorporate all kinds of fibers:

• - synthetics: of polyamide, polyester, acrylic, ceramic, etc. types
• - cellulose acetate, triacetate, viscose, etc.
• - mineral glass, rock wool, carbon, boron, mallastonite, metallic, etc.

The single figure of the appended drawing will make it clear how the invention can be implemented.

This single figure schematically illustrates an embodiment of the present invention.

A - On the one hand in an installation 1, comprising a pulper (or hydrrapulper), a slurry of cellulosic fibers is prepared in any known manner, for example from a mechanical pulp, a semi-chemical pulp, d '' chemical pulp, unbleached pulp, bleached pulp, soda dough, sulphate dough, kraft dough, bisulphate dough, rags, straw paste, etc ... This slurry, in addition to the cellulose fibers and water, can incorporate a coloring matter and is subjected to agitation capable of suspending the fibrous particles.

The weight concentration of the cellulosic fibers is for example between 2.5 and 4% and the pulp thus produced is refined to obtain a dewatering index of between approximately 10 and 60 degrees Shopper.

After refining, the suspension of fibers from installation 1 is introduced (at 2) into a storage tank A.

Optionally, to this suspension of cellulosic fibers, fillers (bonding products and synthetic and / or short mineral fibers, that is to say of which the length is at most equal to approximately 6 mm), are added (in 3). .

The mixture then being in the vat A is treated with one or more cationic agents for preparing cellulose, such as those listed in list 22 above and introduced in 4. This or these cationic agents are fixed on the fibers and polarize them uniformly. The proportion used is generally comprised, by weight, between 0.3 and 5% of the dry fibrous material.

The excess cationic agent and the free particles of the fibrous suspension are then neutralized by a weak ionic polarization solution, of the anionic type, the active substance of which is for example chosen, from those gathered in the list 111 above and introduced in 5. The required amount of this active substance is for example between 0.3 and 15% of the weight of the dry mixture.

Finally, the mixture found in the vat A is treated with an anionic polyelectrolyte, of high molecular weight, introduced in 6 and chosen for example from the list given by list 1 above. The concentration of this anionic polyelectrolyte is for example between 0.2 and 8% by weight of the dry cellulose.

The anionic polyelectrolytes of lists 1 and III are prepared and stored at a concentration of approximately 0.6% a few times before their introduction into 5 and 6 in the vat A.

The mixture thus obtained, contained in the vat A, is stored therein with stirring.

B - In addition, in another vat B capable of generating controlled agitation with constant turbulence movement, a first dose of water is introduced at 7 and at 8 ₁ the first long sized fibers which are difficult to disperse.

As soon as said first fibers are dispersed, a first dose of a high molecular weight polyelectrolyte, for example of the anionic type if the hydrated size of said fibers is also anionic.

This polyelectrolyte is preferably the same as that used in step A above. The concentration by weight of this high molecular weight polyelectrolyte can be between 0.2 and 5% of the weight of said first fibers.

After stabilization of this solution, a second dose of water is introduced into the vat 8 (via 7) and second long fibers with size having the same polarity as the first ones (in 8 ₂ ). These second long fibers are chosen to be less difficult to disperse than said first fibers.

As soon as said second fibers are dispersed, a second dose of high molecular weight anionic polyelectrolyte, for example that previously used, is added at 9. This second dose is adjusted to keep the polyelectrolyte concentration constant, relative to the total amount of fiber and relative to water.

The alternating addition is continued, in the vat 8, of doses of water, long fibers and anionic polyelectrolyte until the nth and last long fibers introduced in 8n.

Then, it is possible to introduce, at 10, other fibers, for example shorter. A nonionic surfactant or of the same polarity (anionic in the example chosen) as the polyelectrolyte used previously is then added.

In the fiber suspension of the vat 8, the slurry of the vat A is then introduced, respecting the proportions chosen for the constitution of the final nonwoven product. The concentration by weight of fibers in the mixture obtained is at least equal to 1%.

This mixture of said fibrous suspension and slurry feeds a hydroformer 11, by means of a pump 12. The liquid mass 13, containing the fibers and feeding the fabric 14 of the hydroformer 11, passes for the most part through said fabric 14 by depositing said fibers thereon in order to form a veil and falls into a receptacle 15 (arrows 16), from which it is brought back to the hydroformer 11 by a pump 17 and a pipe 18. The tank 8 is connected in parallel on line 18, by pump 12.

The concentration by weight of fibers of the liquid mass 13 is for example between 0.1% o and 0.5% o.

Optionally, the pH of the liquid mass 13 is adjusted by adding an acid or a base, before introduction into the hydroformer 11. It has in fact been observed that the balance between the fibers dispersed in the fiber bundles is influenced by the pH value. Each fiber solution has an optimal pH value from this point of view.

The optimum pH value is determined, case by case, by experimentation.

At the outlet of the hydroformer 11, the veil of fibers is optionally treated at the surface with a binder, for example chosen from those from list III above. The treatment can be carried out in a saturation scarf (not shown). Said veil, which is still partially wet, can then be treated with a coating of foam, by wet saturation or spraying before the sheet dries.

EXAMPLE 1

A 3% suspension of cellulose fibers bleached with sodium hydroxide is prepared in a 6000 liter hydrosherper 1. The fibers have an approximate length of 6 mm and the dough is refined at 40 ° Shopper.

• - 500 I. d'eau;
• - 666 1. de la suspension de fibres cellulosiques à 3% (en 2);
• - 0,5 1. d'un agent anti-mousse;
• - 41. de résine polyamide épichlorydrine, par exemple celle vendue par la Société HERCULES sous le nom commercial de KYMENE 557 (en 4);
• - 4,4 1. de carboxyméthylcellulose diluée à 2,5 % en poids, par exemple celle vendue par la Société HERCULES sous le nom commercial de 7 ML (en 5);
• - 11 I. d'une solution à 6 %o de résine polyacrylamide à haut poids moléculaire, par exemple celle vendue par la Société AMERICAN CYANAMID sous le nom commercial de C 130 (en 6).

A) In the vat A, with gentle stirring, the following are introduced in order:

• - 500 I. of water;
• - 666 1. of the suspension of 3% cellulosic fibers (in 2);
• - 0.5 1. of an anti-foaming agent;
• 41. of polyamide epichlorohydrin resin, for example that sold by the company HERCULES under the trade name of KYMENE 557 (in 4);
• - 4.4 1. of carboxymethylcellulose diluted to 2.5% by weight, for example that sold by the company Hercules under the trade name of 7 ML (in 5);
• - 11 I. of a 6% o solution of high molecular weight polyacrylamide resin, for example that sold by the company AMERICAN CYANAMID under the trade name of C 130 (in 6).

It is made up with water to reach a volume of 1400 l and the pH of the suspension is brought back to a value greater than 7.5, by addition of caustic soda or sodium carbonate.

• - 1800 I. d'eau (en 7);
• - 15 kg. de fibres polyester ayant un titre de 6,7 décitex et une longueur de 30 mm (en 8₁);
• - 0,5 I. d'une solution à 6 %o de résine polyacrylamide C130 (en 9);
• - 600 I. d'eau (en 7);
• - 15 kg. de fibres polyester ayant un titre de 11 décitex et une longueur de 34 mm (en 8₂);
• - 0, 166 I. de la solution à 6 %o de C130 (en 9);
• - 600 d'eau (en 7);
• - 15 kg. de fibres polyester ayant un titre de 1,7 décitex et une longueur de 18 mm (en 8₃);
• - 0,166 1. de la solution à 6 %o de C130 (en 9);
• - 600 1. d'eau (en 7);
• - 10 kg. de fibres polyester ayant un titre de 1,7 décitex et une longueur de 6 mm (en 8₄);
• - 0,166 I. de la solution à 6 %o de C130 (en 9);
• - 600 l. d'eau (en 7);
• - 5 kg. de fibres de verre ayant un titre de 1,1 decitex et une longueur de 4,5 mm (en 8₅);
• - 0,5 1. d'un agent dispersant, par exemple celui connu commercialement sous le nom de ZONTES KV (en 9).

B) In the vat B, we successively introduce:

• - 1800 I. of water (in 7);
• - 15 kg. polyester fibers having a titer of 6.7 decitex and a length of 30 mm (in 8 ₁ );
• - 0.5 I. of a 6% o solution of C130 polyacrylamide resin (in 9);
• - 600 I. of water (in 7);
• - 15 kg. polyester fibers having a titer of 11 decitex and a length of 34 mm (in 8 ₂ );
• - 0.166 I. of the 6% o solution of C130 (in 9);
• - 600 water (in 7);
• - 15 kg. polyester fibers having a count of 1.7 decitex and a length of 18 mm (in 8 ₃ );
• - 0.166 1. of the 6% o solution of C130 (in 9);
• - 600 1. of water (in 7);
• - 10 kg. polyester fibers having a count of 1.7 decitex and a length of 6 mm (in 8 ₄ );
• - 0.166 I. of the 6% o solution of C130 (in 9);
• - 600 l. water (in 7);
• - 5 kg. glass fibers having a count of 1.1 decitex and a length of 4.5 mm (in 8 ₅ );
• - 0.5 1. of a dispersing agent, for example that commercially known as ZONTES KV (in 9).

Then, the hydroformer 11 is supplied with the mixture of suspensions contained in the vats A and B, diluted by the pump 17 to provide a liquid mass 13 having a total weight concentration of fibers equal to 1.4%.

• - 60 1. d'une résine styrène acrylique, par exemple celle vendue sous la référence 6147/2 de la Société HOECHST;
• - 4 I. de mélamine CASURIT de la même société; et
• - 0,4 l. du catalyseur NKA de la même société.

Downstream of the hydroformer 11, the fibrous web is treated in a scarf with a solution comprising:

• - 60 1. of an acrylic styrene resin, for example that sold under the reference 6147/2 of the company HOECHST;
• - 4 I. of CASURIT melamine from the same company; and
• - 0.4 l. of the NKA catalyst from the same company.

A sheet of nonwoven product is then obtained, the grammage of which is 130 g / m2, and the elongation of 3%. The longitudinal and transverse tear strengths are 30 and 24 kP respectively. The dimensional stability of the product at 200 ° C is 0.1%.

EXAMPLE II

A 3% suspension of cellulose fibers bleached with sodium hydroxide is prepared in a 6000 1 hydrrapulper 1. The fibers have an approximate length of 6 mm and the dough is refined at 60 ° Shopper.

• - 500 1. d'eau;
• - 100 cm³ d'un agent dispersant anionique, par exemple celui commercialement connu sous le nom DUSPERSE 49, venu par la société BUCKMAN LABORATORIES;
• - 660 1. de la suspension de fibres cellulosiques à 3% (en 2);
• - 0,5 l. d'un agent anti-mousse;
• - 4 de résine polyamide épichlorydrine, par exemple celle vendue par la société HERKULES sous le nom commercial de KYMENE 557 (en 4);

A) In the vat A, with gentle stirring, the following are introduced in order:

• - 500 1. of water;
• - 100 cm ³ of an anionic dispersing agent, for example that commercially known under the name DUSPERSE 49, supplied by the company BUCKMAN LABORATORIES;
• - 660 1. of the suspension of 3% cellulosic fibers (in 2);
• - 0.5 l. an anti-foaming agent;
• - 4 of epichlorohydrin polyamide resin, for example that sold by the company HERKULES under the trade name of KYMENE 557 (in 4);

• - 10 kg de fibres de polyester ayant un titre de 1,7 deniers et une longueur de 6 mm;
• - 5 kg. de fibres de verre ayant un titre de 1,1 décitex et une longueur de 4,5 mm;

4.5 I. of carboxymethylcellulose diluted to 2.5% by weight, for example that sold by the company Hercules under the trade name of 7 ML (in 5);

• - 10 kg of polyester fibers having a count of 1.7 deniers and a length of 6 mm;
• - 5 kg. glass fibers having a count of 1.1 decitex and a length of 4.5 mm;

- 11 l. of a 6% o solution of high molecular weight polyacrylamide resin, for example that sold by the company AMERICAN CYANAMID under the trade name of C130 (in 9).

The pH of the mixture is brought back to the value of 7.5.

• - 1800 1. d'eau (en 7);
• - 15 kg. de fibres polyester ayant un titre de 6,7 décitex et une longueur de 30 mm (en 8₁);
• - 90 1. d'une solution à 6 %o de résine polyacrylamide C130 (en 9);
• - 600 1. d'eau (en 7);
• - 15 kg. de fibres polyester ayant un titre de 11 décitex et une longueur de 34 mm (en 8₂);
• - 30 1. d'une solution à 6 %o de C130;
• - 600 I. d'eau;
• - 15 kg. de fibres polyester ayant un titre de 1,7 décitex et une longueur de 18 mm.;
• - 30 1. d'une solution à 6 %o de C130;
• - 1400 1. de la solution préparée sous A;
• - 100 cm³ de l'agent dispersant GUPERSE 49;
• - 50 cm³ d'agent anti-mousse.

B) In the vat B, we successively introduce:

• - 1800 1. of water (in 7);
• - 15 kg. polyester fibers having a titer of 6.7 decitex and a length of 30 mm (in 8 ₁ );
• - 90 1. of a 6% o solution of C130 polyacrylamide resin (in 9);
• - 600 1. of water (in 7);
• - 15 kg. polyester fibers having a titer of 11 decitex and a length of 34 mm (in 8 ₂ );
• - 30 1. of a 6% o solution of C130;
• - 600 I. of water;
• - 15 kg. polyester fibers having a count of 1.7 decitex and a length of 18 mm .;
• - 30 1. of a 6% o solution of C130;
• - 1400 1. of the solution prepared under A;
• - 100 cm ³ of the dispersing agent GUPERSE 49;
• - 50 cm ³ of anti-foaming agent.

The mixture 13 supplied to the hydroformer 11 has a concentration of 1.6% of fibers.

EXAMPLE III

In the pulper 1, a suspension is prepared at 3% of cellulose fibers bleached with soda, refined at 60 ° Shopper.

• - 500 1. d'eau;
• - 660 1. de la suspension de fibres cellulosiques à 3%;
• - 4 1. de résine polyamide épichlorydrine KYMENE 557;
• - 65 I. d'un liant acrylique dilué à 20 %, par exemple celui portant la référence commerciale P339 et vendu par la société ROHM et HAAS;
• - 11 1. d'une solution à 6 %o de résine polyacrylamide C130;
• - Un complément d'eau pour 1400 l.

A) In the vat A, with gentle stirring, the following are introduced in order:

• - 500 1. of water;
• - 660 1. of the suspension of 3% cellulosic fibers;
• - 4 1. of polyamide epichlorohydrin resin KYMENE 557;
• - 65 I. of an acrylic binder diluted to 20%, for example that bearing the commercial reference P339 and sold by the company ROHM and HAAS;
• - 11 1. of a 6% o solution of C130 polyacrylamide resin;
• - Additional water for 1400 l.

The pH is adjusted to 7.2.

The fibrous slurry thus obtained is mixed with one or other of the fibrous suspensions obtained in step B of Examples 1 or 2.

Claims (15)

1. Method for manufacturing a suspension of long fibres usable in a paper machine, these fibres having a length of at least 12 - 18 - 24 -30 or 34 mm respectively for sizes of 1.7 - 3.3 - 4.4 - 6.7 or 11 decitex,
characterized in that it comprises the following steps:

a) in a first water dose, a first dose of first greased long fibres is suspended and a first dose of a first polyelectrolyte having a high molecular weight and the same ionic character as the hydrated greasing of said first fibres is added thereto, the weight proportion of said first polyelectrolyte being comprised between 0,2 and 0,5 % of the weight of said first fibres;

b) after stabilization of the suspension formed under a), a second water dose is added thereto and then a second dose of second long fibres, the hydrated greasing of which has the same ionic character as that of said first fibres, as well as a second dose of a second polyelectrolyte having a high molecular weight and the same ionic character as the hydrated greasing of said second fibres, the cumulated weight proportion of the first and second polyelectrolytes with respect to the cumulated weight of said first and second fibres remaining within the same range as that of said first polyelectrolyte with respect to said first fibres;

c) the manufacturing of said suspension of long fibres is carried on up to the nths adding to the cumulated suspension containing the (n-1)th first fibres, a nth water dose and then a nth dose of nth long fibres, the hydrated greasing of which has the same ionic character as that of the (n-1 )th fibres, as well as a nth dose of a nth polyelectrolyte having a high molecular weight and the same ionic character as the hydrated greasing of said (n-1)th fibres, the cumulated weight proportion of the n polyelectrolytes with respect to the cumulated weight of said n fibres remaining within the same range as that of the first polyelectrolyte with respect to said first fibres.

2. Method for industrial manufacturing by paper process of a non-woven sheet product comprising greased long fibres, these fibres having a length of at least 12 - 18 - 24 - 30 or 34 mm respectively for sizes of 1.7 - 3.3 - 4.4 - 6.7 or 11 decitex,
characterized in that:

A) a slurry of cellulose fibres is first made, the weight concentration in fibres of which is comprised between 2.5 and 4 % and the dropping index of which is comprised between about 10 and 60 Shopper degrees,

B) a suspension of long fibres is further made operating the way described in claim 1; then

C) said slurry of cellulose fibres is incorporated with said suspension of the n long fibres and a paper machine is fed with the mixture resulting from the incorporation.

3. Method according to one of claims 1 or 2, characterized in that the long fibres mentioned in the plurality of operations a), b) and c) are of different diameters, lengths and natures.

4. Method according to one of claims 1 or 2,
characterized in that the long fibres mentioned in the plurality of operations a), b) and c) are of same nature, but of different diameters and lengths.

5. Method according to any one of claims 1 to 4,
characterized in that the n polyelectrolyte doses consist of the same product.

6. Method according to any one of claims 1 to 5, carried out for long fibres, the hydrated greasing of which is of the anionic type,
characterized in that the polyelectrolyte doses consist of at least one following material:

- polyacrylamide resin

- polyamidamine resin

- polyamine resin

- carboxyvinylic resin

- polyethylenamine resin

- modified polyethylenamine resin.

7. Method according to any one of claims 2 to 6,
characterized in that short fibres of different natures are mixed with the cellulose fibres of said slurry.

8. Method according to claim 2 and any one of claims 5 to 7, wherein the cellulose fibre slurry undergoes a polyelectrolyte treatment,
characterized in that at least one polyelectrolyte of said treatment of said slurry is the same as the high molecular weight polyelectrolyte used in the manufacturing of said long fibre suspension.

9. Method according to any one of claims 1 to 8,
characterized in that, during the manufacture of the long fibre suspension, the latter are incorporated according to a decreasing order of difficulties in creating and maintaining the suspension.

10. Method according to any one of claims 1 to 9,
characterized in that, after successive incorporation of the long fibres in said suspension, shorter fibres of different nature are added thereto.

11. Method according to any one of claims 2 to 10,
characterized in that, at the exit of the paper machine, the sheet of the non-woven product undergoes a reinforcement surface treatment.

12. Non-woven sheet product industrially obtained by paper process and comprising cellulose fibres,
characterized in that it further comprises mineral or organic fibres, the length of which is at least 12 - 18 - 24 - 30 or 34 mm respectively for sizes of 1.7 - 3.3 - 4.4 - 6.7 or 11 decitex, the long fibres forming at least 30 % of the dry weight of said product.

13. Non-woven product according to claim 12,
characterized in that it further comprises shorter mineral or organic fibres.

14. Non-woven product according to one of claims 12 or 13,
characterized in that it comprises glass fibres and polyester fibres.

15. Non-woven product according to claim 14,
characterized in that it is provided with a coating making it tight in view of being used in the building industry.

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