FR2571388A1 - NON-WOVEN LENGTH SHEET PRODUCT AND ITS PAPERMAKING PROCESS - 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 products

  long fiber sheet and their method of manufacture by

paper path.

  Although not exclusively, the present invention is particularly suitable for the production of a dimensionally stable composite sheet capable of presenting, at very high resistance to punching, which can be impregnated, either bitumen or the like, for example for use in sealing buildings (including the roof thereof), or a resin serving as dimensional stabilization reinforcement. For purposes of clarity of exposure of the invention, the latter will be explained hereinafter with the aid of such an example, which of course should not be considered as limiting the scope of the invention.

present invention.

  It is known that fibrous composite sheet products intended for sealing in the building industry must have the following properties: good dimensional stability; - good resistance to aging; good resistance to atmospheric agents, to chemicals, to thermal shocks, to hygrothermal variations of the support on which they are arranged, etc .; - good resistance to punching, especially if men and equipment must circulate on said products, after installation; - good resistance to abrasion; and a good aptitude for impregnation with bitumen, elastomers, etc., with a view to making them watertight.

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  1 Such properties are sometimes contradictory and do not

  can be obtained by means of a single kind of fibers.

  It is therefore necessary to implement several kinds of different fibers, which may also have different lengths and / or diameters. For example, aging resistance and dimensional stability are provided by long glass fibers, while puncture resistance is achieved by

  polyester also of great length.

  Currently, such a product is for example made by the superposition of a fiberglass web and a web of polyester fibers, assembled to one another (complexing)

  and impregnated with bitumen, a resin or the like.

  However, such a known product does not make it possible to obtain optimum properties. Indeed, in order to give the glass mat a sufficient mechanical strength, allowing the 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; As a result, the latter is too rigid and does not withstand the impact stresses or the dimensional variations of its support. Moreover, the polyester fiber web is produced, in a known manner, by the continuous molten method,

  so that the polyester fibers are only partially

  stretched and their length is not stabilized: the result is that the finished product is less stable

  dimensionally that it should be.

  The present invention aims to overcome these disadvantages. Some of his main goals are

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so the following ones:

  - to produce a fibrous product in stable dimensional sheet-

  It can be thermally impregnated and formed into a composite sheet in which fibers of different types, lengths and / or diameters are intimately mixed, in order to obtain better properties for the finished product and the possible incorporation of fillers. , inert or capable of conferring other properties on the finished product; - reduce the proportion of glass fibers or the like to a fair enough quantity, in order to improve the resistance of the finished product to dimensional and dimensional constraints - to allow the use of polyester fibers or

  analogues of great length stretched to their

  dimensioning, in order to improve the stability

dimensional aspect of the finished product.

  To achieve these objectives, it would be advantageous to be able to implement the process for manufacturing nonwoven fibrous products wet on a paper machine; however, this is so far impossible. It is known that in order to manufacture wet non-woven products, fibers are first dispersed 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 helix. Such a cuvier serves as a steering wheel for feeding a hydroformer, on the inclined web which is formed by filtration of the web of nonwoven material. So, this wet technique

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  manufacturing of non-woven products is modeled on the

  paper manufacturing technique.

  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 man's artificial and synthetic fibers.

great length.

  Indeed, the agitation of the fibers, necessary for the dispersion thereof and the homogenization of the suspension, causes agglomerations of fibers beyond certain thresholds of length of said fibers. Suspending in the pulper and storage in the vat thus limit the usable length of the fibers. For example, the length of the usable fibers is thus limited to 6 mm for a titre of 1.7 decitex and to 1015 mm for fibers of higher titers, at usual concentrations of 0.5 to 1%.

supply 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 sizing necessary for the manufacture of these cables. After introduction into the water and under the effect of agitation, the bundles are disintegrated, but at the same time, the released fibers are knotted together, the more rapidly that they are longer and the The size is less stable, especially because of the addition of peptizing agents, surfactants,

wetting and dispersing agents.

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  In order to avoid certain effects of these sizings, de-sizing solutions are already known for pre-impregnating the bundles of fibers prior to their introduction into the pulper. Generally, the fibrous bundles, pretreated in such a desizing solution, open completely in the space of 10 to 15 seconds. However, in the case of long fibers, such desizing solutions do not prevent the reagglomeration of the fibers, especially since certain fibers, such as glass or polyester fibers, have a tendency to agglomerate by attraction. mutual. Such fibers, after dispersion, do not knot, but agglomerate into bundles of contiguous fibers. To overcome this drawback, it has already been proposed to add polyelectrolytes to the dispersion liquid, which makes it possible to electrically charge the fibers as they leave the fiber bundles during the dispersion, so that they are more likely to

  to attract each other after separation.

  In some cases, to avoid reagglomeration 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, either by introducing air into this liquid.

  It has further been noted that, if fiber bundles are dispersed in a medium which already contains dispersed long fibers, the dispersion of said bundles is hindered, especially since the fibers already dispersed are all the more long. On the other hand, if the medium contains already dispersed short fibers such as certain paper fibers, the dispersion of

  Long fiber bundles can be favored.

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  However, these observations and proposals are the result of laboratory experiments and are insufficient in themselves to solve the difficulties mentioned above and to enable paper-based long-fiber non-woven products to be industrially produced. In view of the foregoing, other objects of the present invention are therefore, from the known elements of the prior art mentioned above: a sheet of non-woven product, containing long cellulosic, synthetic, mineral fibers , etc. .., dimensionally stable and thermally stable, obtained industrially by paper; the industrial production of such a sheet on a known machine for manufacturing a non-woven product by papermaking, with fibers of different lengths and / or different diameters; the preparation, for use on a paper machine, of an aqueous suspension of length fibers

and / or of different diameters.

  By long fibers, is meant in the present description

  fibers whose length is greater than 6 mm for a

  1.7 decitex and 15 mm for senior titles.

  By way of example, the present invention makes it possible to manufacture nonwoven products by papermaking from fibers whose length is at least equal to:

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

  For these purposes, according to the invention, the method for carrying out

  industrial paper-making of a non-woven product

  made from long sized fibers, is remarkable

  in that: A) A slurry of cellulosic fibers is first made, the fiber concentration of which is between 2.5 and 4% and the dripping index is between about 10 and 60 degrees Shopper; B) A suspension of long fibers is also carried out by operating in the following manner: a) in a first dose of water, a first dose of first long sized fibers is suspended and a first dose of a first dose is added thereto; high molecular weight polyelectrolyte of the same ionic character as the hydrated size of said first fibers, the weight proportion of said first polyelectrolyte being between 0.2 and 5% of the weight of said first fibers

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  1 b) after stabilization of the suspension produced under a), a second dose of water is added thereto, followed by 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 proportion

  cumulative weight of the first and second polyelectro-

  lytes 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 to the nth fibers is continued by adding to the eumulated suspension containing the (n-1) th 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 nth dose of a nth high molecular weight polyelectrolyte of the same ionic character as the hydrated size of said (n-1) 1) the second fibers, the cumulative weight ratio of n polyelectrolytes relative to the cumulative weight of said n fibers remaining in the same range as that of the first polyelectrolyte relative to said first fibers; then, C) said cellulosic fiber slurry is incorporated in said suspension of the long fibers and fed to a

  paper machine with the mixture resulting from the incorporation

tion.

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  Thus, by virtue of the present invention, the degree of bursting of the long fiber bundles is controlled and can be maintained in a controlled open position for a sufficiently long time, which corresponds to that which elapses between suspending the fibers in preparation and introducing them into the papermaking machine. Indeed, when the bundles of long fibers are introduced into the water, their size hydrates and generates ionic forces allowing their division until

  elementary fibers. If this water contains a polyelectrolyte

  lyte of the same electric charge as the hydrated sizing, a field of de-forces is created within the liquid, whose intensity

  depends on the proportion of said polyelectrolyte. By choosing

  If this proportion is adequate, it can be ensured that there is a balance between the ionic-division forces due to the hydrated size and the forces due to the polyelectrolyte: the fibers are then split into fibers. avoiding their reagglomeration. It is then possible, by determining the adequate proportion of the polyelectrolyte, to maintain the balance of forces up to

  introduction into the paper machine.

  Operating according to the invention, dose of long fibers after long fiber dose, the beams of each fiber dose (except for the first) are dispersed in a liquid medium already containing dispersed fibers in equilibrium. This results in a cumulative synergistic effect, favored by the fact that the addition of a new dose of

  polyelectrolyte keeps the content of it constant.

  Thanks to the method according to the invention in cumulative stages, it is possible to obtain, in the suspension, a much larger concentration of dispersed fibers than that which could be obtained by introducing all the fibers

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  1 long in one go. Then, the addition of the cellulosic fiber slurry makes it possible to maintain the

  dispersion of long fibers to the paper machine.

  It will be noted that, in the implementation of the invention, the sizing of the fibers is very important, since it determines the choice of high molecular weight polyelectrolytes to be used: depending on the types of sizing, these polyelectrolytes must be chosen anionic type or

of cationic type.

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

different.

  Similarly, the n polyelectrolytes used in this plurality of operations may be different; however, it is advantageous that the n doses of polyelectrolytes required for the preparation of the fiber suspension

  long consist of the same product.

  In the most frequent case where the hydrated size of the long fibers used is of the anionic type, the high molecular weight anionic polyelectrolyte (s) used in the n operations a), b) and c) of step B can be chosen. among the substances listed in List I below:

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  polyacrylamide resin - polyamidamine resin - polyamine resin (I) carboxyvinyl resin - polyethylenamine resin - modified polyethylenamine resin Advantageously, short fibers of different natures, synthetic or mineral, can be mixed with the fibers

cellulosic of said slurry.

  Moreover, in a known manner, this slurry can undergo a

  known treatment based on polyelectrolytes.

  For example, it is customary to treat a cellulose slurry with the cationic products listed in list II below - aluminum sulphate - aluminum chloride - calcium and sodium aluminate - polyethylenamine - polyamide epichlorohydrin resin - polyamide resin amine - aminoplast resin (II) - phenol resin - starch - carboxymethyl starch - polysaccharide - galactomane - hydrochloride

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  Similarly, it is usual to treat a cellulose slurry with the anionic products listed in list III below: carboxymethylcellulose - gelatin - methylethylcellulose - polyvinyl alcohol - alginate - dextrin (III) - monogalactan - polysaccharide - carboxyvinyl resin - copolymer In the case where the slurry of cellulose fibers, optionally containing other mineral or synthetic fibers, undergoes such a treatment, it is advantageous for at least one polyelectrolyte of said treatment to be the same as the high-molecular polyelectrolyte. molecular weight used in the n operations of step B) of preparing the

suspension of long fibers.

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

increasing title.

  After successive incorporation of the long fibers into said suspension, fibers may be added thereto

  shorter, for example of different natures.

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  Thus, the present invention relates to a sheet nonwoven product obtained industrially by paper and

  comprising cellulosic fibers. This product is remarkable

  in that it contains mineral or organic fibers the length of which is at least 12-18-24-30 or 34 mm respectively for headings 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, shocks and tears,

  while undergoing significant lengthening.

  Indeed, for this, it is sufficient to provide fibers and high titre to provide resistance to punching and tearing, and lower-grade fibers to give the

  punctual resistance and cohesion.

  Optionally, such a product may undergo a treatment of

reinforcing surface.

  It can incorporate all kinds of fibers: - synthetic: polyamide, polyester, acrylic,

ceramic, etc ...

  - cellulose: acetate, triacetate, viscose, etc ... - mineral: glass, rock wool, carbon, boron,

mallastonite, metallic, etc ...

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  The single figure of the appended drawing will make it clear

  how the invention can be realized.

  This unique figure schematically illustrates a mode of implementation

  of the present invention.

  On the one hand in a plant 1, comprising a pulper (or hydrapulper), a slurry of cellulosic fibers is prepared in any case known, for example from a mechanical pulp, a michimic paste, a chemical pulp, unbleached pulp, bleached pulp, soda paste, sulphate pulp, kraft pulp, sulphate pulp, dough of rags, This slurry, in addition to cellulosic fibers and water, may incorporate a dyestuff and is subjected to stirring capable of suspending

fibrous particles.

  The concentration by weight of the cellulosic fibers is for example between 2.5 and 4% and the dough thus produced is refined to obtain a drip index between

about 10 and 60 degrees Shopper.

  After refining, the suspension of the fibers coming from the installation 1 is introduced (in 2) into a storage tank A. Optionally, to this suspension of cellulosic fibers is added (in 3) fillers, gluing products and synthetic fibers and / or short mineral, that is to say

  whose length is at most equal to about 6 mm.

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  The mixture then in the cuvier A is treated with one or more cationic agents for the preparation of cellulose, such as those listed in list II above and introduced in 4. These cationic agents bind to the fibers and polarize them evenly. The proportion used is generally from 0.3 to 5% by weight of the dry fibrous material. The excess of cationic agent and the free particles of the fibrous suspension are then neutralized by a weak ionic polarization solution, of anionic type, the active substance of which is for example chosen from those in list III above. and introduced in 5. The required amount of this active substance is

  example included in 0.3 and 15% of the weight of the dry mixture.

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

dry cellulose.

  The anionic polyelectrolytes of lists I and III 'are prepared and stored at a concentration of about 0.6% for some time before their introduction in 5 and 6 in the vat A. The mixture thus obtained, contained in the vat A, is

  stored therein with stirring.

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  B - On the other hand, in another vat B capable of generating controlled stirring constant turbulence movement, is introduced, at 7, a first dose of water and 81 first long fiber size difficult to disperse. As soon as said first fibers are dispersed, at 9

  first dose of a high molecular weight polyelectrolyte

  laire, for example of the anionic type if the hydrous sizing

  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 B (through 7) and second long sizing fibers of the same polarity as the first (at 82). These second long fibers are chosen to be less difficult to disperse

than said first fibers.

  As soon as the said second fibers are dispersed, a second dose of anionic polyelectrolyte of high molecular weight, for example that previously used, is added at 9. This second dose is adjusted to keep the polyelectrolyte concentration constant, in relation to the quantity

  total fiber and in relation to water.

  The alternating addition of water, long fiber and anionic polyelectrolyte in the vat B to the nth and last long fibers introduced at 8n is continued.

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  Then, it is possible to introduce, at 10, other fibers, for example shorter ones. A nonionic surfactant or the same polarity (anionic

  the example chosen) that the polyelectrolyte used previously

  is lying. In the fibrous suspension of the cuvier B, the slurry of the cuvier A is then introduced, respecting the proportions chosen for the constitution of the final nonwoven product. The fiber concentration of the mixture obtained is

less than 1%.

  This mixture of said fibrous suspension and slurry feeds a hydroformer 11, via a pump 12. The liquid mass 13, containing the fibers and feeding the web 14 of the hydroformer 11, for the most part passes through said web 14 by depositing said fibers thereon to form a web and falls into a receptacle (arrows 16), o o it is brought back to the hydroformeur.11 by a pump 17 and a pipe 18. The cuvier B is

  connected in parallel on the pipe 18, by the pump 12.

  The weight concentration of fibers of the liquid mass 13

  is for example between 0.1% and 0.5%.

  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 indeed been noted that the balance between the fibers dispersed fiber bundles was influenced by the pH value. With each fibrous solution

  corresponds to an optimal pH value from this point of view.

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  1 The optimum pH value is determined, case by case, by experimentation. At the outlet of the hydroformer 11 the fiber web is optionally surface-treated with a binder, for example chosen from those of list III above. The treatment can be performed in a saturation scarf (not shown). The still partially wet web may then be treated with foam coating, wet saturation or spraying prior to drying of the web.

leaf.

EXAMPLE I

  In a hydrapulper 1 of 6000 liters, is prepared with rapid stirring, a suspension of 3% sodium-bleached cellulose fibers. The fibers have a length

  approximately 6 mm and the dough is refined to 40 Shopper.

  A) In the vat A, with low stirring, are introduced in the order: 500 1. of water; - 666 1. the suspension of 3% cellulosic fibers (in

2);

  - 0.5 1. an anti-foam agent; - 4 1. polyamide epichlorydrin resin, for example that sold by the company HERCULES under the trade name KYMENE 557 (in 4); 4.4% 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);

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  - 11 l. a solution with 6 / 00oo of high molecular weight polyacrylamide resin, for example that sold by AMERICAN CYANAMID under the trade name of C 130

(in 6).

  It is completed 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. B) In the vat B, are successively introduced: - 1800 1. of water (in 7); - 15 kg. polyester fibers having a title of 6.7 decitex and a length of 30 mm (at 81); 0.5% of a 6% solution of polyacrylamide resin C130 (at 9); 600 1. of water (in 7); - 15 kg. of polyester fibers having a title of 11 decitex and

a length of 34 mm (at 82); -

  - 0.166 1. of the 6% solution of C130 (in 9) - 600 liters of water (in 7); 15 kg. polyester fibers having a title of 1.7 decitex and a length of 18 mm (in 83); - 0.166 1. of the solution at 6 / oo C130 (in 9); - 600 1. of water (in 7); - 10 kg. polyester fibers having a title of 1.7 decitex and a length of 6 mm (at 84); - 0.166 1. of the solution at 6 / oo C130 (in 9); - 600 1. of water (in 7); - 5 kg. glass fiber having a titer of 1.1 decitex and a length of 4.5 mm (in 85);

-5 2571388 - 0.5 1. of a dispersing agent, for example that known -

  commercially under the name ZONTES KV (in 9).

  Then, the hydroformer 11 is fed with the mixture of the suspensions contained in the vats A and B, diluted by the pump 17 to provide a liquid mass 13 having a total fiber concentration equal to 1.4%; Downstream of the hydroformer 11, the fibrous web is treated as a scarf by a solution comprising - 60 1. a styrene acrylic resin, for example that sold under the reference 6147/2 of the company HOECHST; - 4 1. CASURIT melamine from the same company; and

  - 0.4 1. NKA catalyst of the same company.

  A nonwoven product sheet having a basis weight of 130 g / m 2 and an elongation of 3% are then obtained. Longitudinal and transverse resistances to tearing

  are respectively 30 and 24 kP. Dimensional stability

  the product at 200 ° C is 0.1%.

EXAMPLE II

  In a hydrapulper 1 of 6000 l, a suspension with 3% of sodium-bleached cellulose fibers is prepared with rapid stirring. The fibers have an approximate length of

  6 mm and the dough is refined to 600 Shopper.

  A) In the vat A, with low agitation, the following are introduced:

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  1 - 500 1. of water; - 100 cm3 of an anionic dispersing agent, for example that commercially known under the name DUSPERSE 49, come from the company BUCKMAN LABORATORIES; - 660 1. the suspension of cellulosic fibers at 3% (in 2); - 0.5 1. an anti-foam agent; - 4 1. polyamide epichlorydrin resin, for example that sold by the company HERKULES under the trade name KYMENE 557 (in 4); 4.5% 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. polyester fiber having a denier of 1.7 denier and a length of 6 mm; - 5 kg. glass fiber having a titer of 1.1 decitex and a length of 4.5 mm; - 11 1. a solution to 6 / oo of high molecular weight polyacrylamide resin, for example that sold by the company American Kanamid under the trade name C130 (in 9).

  The pH of the mixture is reduced to 7.5.

  B) In the vat B, are successively introduced: - 1800 1. of water (in 7); - 15 kg. polyester fibers having a title of 6.7 decitex and a length of 30 mm (at 81); 90% of a 6% solution of polyacrylamide resin C130 (at 9); - 600 1. of water (in 7);

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  1 - 15 kg. polyester fibers having a title of 11 decitex and a length of 34 mm (at 82); 1. a 6% solution of C130; - 600 1. of water; - 15 kg. of polyester fibers having a title of 1.7 decitex

and a length of 18 mm .; -

  1. a 6% solution of C130; - 1400 1. of the solution prepared under A; 100 cm3 of the dispersing agent GUPERSE 49;

- 50 cm3 of antifoaming agent.

  The mixture 13 supplied to the hydroformer 11 has a concentration

1.6% fiber.

EXAMPLE III

  In the hydrapulper 1, a suspension is prepared at 3% of sodium-bleached cellulose fibers, refined at 60 Shopper. A) In the vat A, with gentle stirring, are introduced in the order: - 500 1. of water; - 660 1. the suspension of cellulosic fibers at 3%; - 4 1. polyamide epichlorydrin resin KYMENE 557; - 65 1. an acrylic binder diluted to 20%, for example that bearing the commercial reference P339 and sold by the company Rohm and Haas; 1. a 6% solution of polyacrylamide resin C130;

- A supplement of water for 1400 1.

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The pH is set to 7.2.

  The fibrous slurry thus obtained is mixed with one or the other of the fibrous suspensions obtained in stage B

examples 1 or 2.

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Claims (10)

  1 - Process for producing a long fiber suspension for use on a papermaking machine, characterized in that the following procedure is performed: a) in a first dose of water, a first dose of first 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, the weight proportion of said first polyelectrolyte being between 0.2 and 0.5% of the first weight of said first fibers; b) after stabilization of the suspension produced under a), there is added thereto a second dose of water, then a second dose of second long fibers, whose hydrated size has the same ionic character as that of said first fibers, as well as a second   dose of a second high molecular weight polyelectrolyte   having the same ionic character as the hydrated size of said second fibers, the cumulative weight ratio of the first and second polyelectrolytes relative to the cumulative weight of said first 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 to the nth is continued by adding to the accumulated suspension containing the (n-1) th first fibers, an nth dose of water, then an nth dose of 2571388   1 nth long fibers, whose hydrated size has the same ionic character as that of the (n-1) th fibers, as well as an nth dose of a nth high molecular weight polyelectrolyte of the same ionic character as the hydrous sizing of said (n-1) th th fibers, the cumulative weight ratio of the n polyelectrolytes relative to the cumulative weight of said n fibers remaining in the same range as that of the first polyelectrolyte   relative to said first fibers.   2 - Process for the industrial production by papermaking of a non-woven sheet product based on long-sized fibers, characterized in that: A) It begins by making a slurry of cellulosic fibers, the weight concentration of fibers is included between 2.5 and 4% and whose dripping index is between about 10 and 60 degrees Shopper B) A suspension of long fibers is also produced by operating 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 weight proportion of said first polyelectrolyte being included; between 0.2 and 5% of the weight of said first fibers; 26 2571388   b) after stabilization of the suspension produced under a), there is added thereto a second dose of water, then a second dose of second long fibers, whose hydrated size 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 ratio of the first of the 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 to the nth fibers is continued by adding to the cumulated suspension containing the first (n-1) th   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 nth dose of a nth high molecular weight polyelectrolyte of the same ionic character as the hydrated size of said (n-1) ths fibers, the cumulative weight ratio of n polyelectrolytes relative to the cumulative weight of said n fibers remaining in the same range as that of the first polyelectrolyte relative to said first fibers; then, C) said cellulosic fiber slurry is incorporated in said suspension of the long fibers and fed to a   paper machine with the mixture resulting from the incorporation tion. 27 2571388   3 - Method according to one of claims 1 or 2,   characterized in that the long fibers mentioned in the plurality of operations a), b) and c) are of natures, of   different lengths and diameters.   4 - Method according to one of claims 1 or 2,   characterized in that the long fibers mentioned in the plurality of operations a), b) and c) are of the same nature,   but of different lengths and diameters.   - Process according to any one of claims 1 to 4,   characterized in that the n doses of polyelectrolyte are consisting of the same product.   6 - Process according to any one of claims 1 to 5,   implemented for long fibers including anionic hydrated size, characterized in that the polyelectrolyte doses consist of at least one substance from the following list: polyacrylamide resin polyamidamine resin polyamine resin carboxyvinyl resin 16 polyethylenamine resin - modified polyethylenamine resin   7 - Process according to any one of claims 2 to 6,   characterized in that short fibers of different natures are mixed with the cellulosic fibers of said slurry.   8 - Process according to claim 2 and any one of   Claims 5 to 7, according to which the fiber slurry   cellulosics undergoes a polyelectrolyte-based   characterized in that at least one polyelectrolyte of said   treatment of this slurry is the same as polyelectrolyte   high molecular weight lyte used in the production of   said suspension of long fibers.   9 - Process according to any one of claims 1 to 8,   characterized in that, in the production of the long fiber suspension, these are incorporated in a decreasing order of difficulties of placing and keeping in suspension.   - Process according to any one of claims 1 to 9   characterized in that, after successive incorporation of the long fibers into said suspension, it is added thereto   shorter fibers of different types.   11il - Process according to any one of claims 2 to 10   characterized in that, at the exit of the papermaking machine, the sheet of the nonwoven product is subjected to a treatment of reinforcing surface.   12 - Non-woven sheet product obtained industrially by paper and comprising cellulosic fibers, characterized in that it also incorporates 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 represent   at least 30% of the dry weight of said product. 29 2571388   1 13 - Nonwoven product according to claim 12, characterized in that it additionally incorporates fibers   mineral or organic shorter.   14 - nonwoven product according to one of claims 12 or 13   characterized in that it comprises glass fibers and polyester fibers.   - Nonwoven product according to claim 14, characterized in that it is provided with a coating making it waterproof for use in the building industry.