EP3898159A1

EP3898159A1 - Method for manufacturing a fibrous material pre-impregnated with thermoplastic polymer in a fluidised bed

Info

Publication number: EP3898159A1
Application number: EP19817366.8A
Authority: EP
Inventors: Gilles Hochstetter; Thibaut SAVART; Arthur Pierre BABEAU; Axel SALINIER
Original assignee: Arkema France SA
Current assignee: Arkema France SA
Priority date: 2018-12-18
Filing date: 2019-12-16
Publication date: 2021-10-27
Also published as: EP3670128B1; CN113226682B; US20220063137A1; CN113226682A; KR20210104819A; EP3670128A1; JP2022512441A; WO2020126996A1

Abstract

Method for manufacturing a material comprising a fibrous material with continuous fibres and a thermoplastic polymer matrix, the material being produced as a unidirectional band, the method comprising a step of pre-impregnation of a strand (81a) of the fibrous material by the matrix in powdered form, the pre-impregnation step being carried out in a fluidised bed (22) comprising a grooved roller component (82), the strand (81a) being in contact with the surface of the roller component (82) and comprising up to 0.1% by weight of sizing, the matrix rate being controlled by controlling the dwell time in the powder and by constantly controlling the tension of the strand (81a) when it is introduced into the fluidised bed.

Description

PROCESS FOR THE MANUFACTURE OF A PRE-IMPREGNATED FIBROUS MATERIAL OF THERMOPLASTIC POLYMER IN A FLUIDIZED BED

The present invention relates to a process for manufacturing a fibrous material pre-impregnated with a thermoplastic polymer in a fluidized bed.

More particularly, the invention relates to a process for manufacturing a prepreg fibrous material comprising a step of prepreg of a non-sized or slightly sized fibrous material for the preparation of an impregnated fibrous material, in particular to core, of reduced and controlled porosity, with a view to obtaining ribbons of impregnated fibrous material, of calibrated dimensions, directly usable for the manufacture of three-dimensional composite parts. In the present description, the term "fibrous material" means an assembly of reinforcing fibers. Before its pre-impregnation and its shaping, it is in the form of wicks. After its shaping and impregnation, in particular at the heart of the wicks of fibers, it is in the form of ribbons (or tapes), strips, or sheets. When the reinforcing fibers are continuous, their assembly constitutes a fabric or a nonwoven (NCF). When the fibers are short, their assembly constitutes a felt or a fiber mat.

In the present description, the term "strip" is used to denote strips of fibrous material whose width is greater than or equal to 400mm. The term "ribbon" is used to designate ribbons of calibrated width and less than or equal to 400mm.

The term "wick" is also used to refer to the fibrous material.

Such prepreg fibrous materials are especially intended for the production of light composite materials for the manufacture of mechanical parts having a three-dimensional structure and having good mechanical and thermal properties. When the fibers are made of carbon or the resin is loaded with suitable additives, these fibrous materials are capable of removing electrostatic charges. They therefore have properties compatible with the manufacture of parts, particularly in the fields of mechanics, civil or military aeronautics, and nautical, automotive, oil and gas, in particular offshore, storage of gas, energy, health and medical, military and armaments, sports and leisure, and electronics. However, the use of non-sized fibers is a necessity for aeronautics and offshore. In fact, in particular for manufacturing structural parts and / or subjected to extreme chemical / thermal environments, it is necessary that not only the polymer used is capable of withstanding the stresses of the part; but it is also necessary that the fiber / matrix interface is the best possible for better resistance of the composite, both in transmission of mechanical forces from the resin to the fibers and in chemical resistance for example. The strengths of these links between the matrix and the fibers are dictated by the quality of impregnation of the material (limited porosity) and by the nature of the physico-chemical or even mechanical links between the fiber and the polymer matrix.

In order to improve the physico-chemical links between polymer and fibers, fiber manufacturers use sizes whose composition and rate may vary. However, being generally organic in nature (thermosetting or thermoplastic resin type) and very often formulated for the impregnation of fibers by polymers with a low melting point or thermosetting with a low Tg point, the sizes are often degraded by the processes of impregnation, in particular during the pre-impregnation stages (molten route, passage into a solvent solution, etc.) and / or during the stages of melting the thermoplastic matrix, in particular when it has a high melting point (for a semi -crystalline or a high Tg (for an amorphous or thermosetting) .In addition, the chemical compatibility between the polymer of the matrix and the size is not always optimal; the resulting grip strength can be modified in positive as negative compared to that observed with a non-sized fiber.

This therefore poses a certain number of difficulties for the manufacture of tapes by means of a pre-impregnation process with a dry powder (or mixture of powders), in particular in the case where each wick is pre-impregnated. powder separately from the others. In most cases, the wick (s) are guided by fittings (generally in the form of rolls) placed in a tank containing either the fluidized bed or an aqueous dispersion.

Thus, international application WO20181 15736 describes a process for pre-impregnating a fibrous material in a fluidized bed, the powder level of which depends on the residence time in the fluid bed and the tension on the wick (s) is controlled using a creel present before the tank comprising the fluidized bed. The use of at least one fixture (in particular a cylindrical roller of convex, concave or cylindrical shape) in the fluidized bed makes it possible to improve the prepreg compared to the methods of the prior art and the fibrous material used can be sized or not sized.

It is not specified in this request if the rollers used are smooth or grooved (or notched).

The article by Gibson A. et al. (composites manufacturing, Vol. 3, N ° 4 (1992)) describes a step of pre-impregnation in a fluidized bed of a fibrous material with a thermoplastic polymer comprising smooth rollers in the fluidized bed with control of the fiber content by means a vibrating system placed at the tank outlet.

However, when these rollers are smooth, the fact that the fibers are not sized leads to a very large and especially very fluctuating development of the wick of fibers, which directly impacts the rate of powder carried by the wick (s) of fibers and makes this variable and uncontrolled rate.

In low tension conditions, whether the fibers are sized or not, the control of the residence time is no longer sufficient to control the powder content and the too low tension causes twisting and / or winding of the locks (twist).

However, in the case of non-sized fibers, too great a tension of the fibers causes the latter to be damaged in contact with the rollers and produce a lot of cut fibrils (fuzz in English) which pollute the fluidized bed and disturb the quality of the fluidization. and therefore the quality of pre-impregnation of the tape.

It is therefore necessary to be able to control the powder rate with fibers that are not sized and this continuously over time without damaging them. The invention therefore aims to remedy the drawbacks of the prior art.

The subject of the invention is therefore a method of manufacturing a prepreg fibrous material comprising a fibrous material made of continuous fibers and at least one thermoplastic polymer matrix, comprising a prepreg step, in particular homogeneous, of said fibrous material having in the form of a wick or of several parallel wicks with at least one thermoplastic polymer matrix in the form of a powder, said pre-impregnation step being carried out on a non-sized fibrous material in a tank comprising a fluidized bed provided with cylindrical grooved rollers . The invention also relates to a unidirectional ribbon of impregnated fibrous material, in particular ribbon wound on a reel, characterized in that it is obtained by a process as defined above.

The invention further relates to a use of the ribbon as defined above in the manufacture of three-dimensional parts. Said manufacture of said composite parts relates to the fields of transport, in particular automobile, oil and gas, in particular offshore, gas storage, civil or military aeronautics, nautical, rail; renewable energies, in particular wind, tidal, energy storage devices, solar panels; thermal protection panels; sports and recreation, health and medical, security and electronics.

The invention also relates to a three-dimensional composite part, characterized in that it results from the use of at least one unidirectional ribbon of impregnated fibrous material as defined above.

The subject of the invention is a process for manufacturing a prepreg fibrous material comprising a fibrous material made of continuous fibers and at least one thermoplastic polymer matrix, characterized in that said prepreg fibrous material is produced in a single unidirectional ribbon or in a plurality of parallel unidirectional ribbons and in that said method comprises a step of prepregnation, in particular homogeneous, of said fibrous material in the form of a wick (81 a) or of several parallel wicks by said at least a thermoplastic polymer matrix in the form of a powder, said pre-impregnation step being carried out by the dry process in a tank (20) comprising a fluidized bed (22) comprising at least one engorged loading part (82),

said wick (81 a) or said wicks being in contact with part or all of the surface of said at least one siphoned fitting piece (82) and said wick (81 a) or said wicks comprising up to 0, 1% by weight of size,

and the control of the rate of said at least one thermoplastic polymer matrix in said fibrous material being carried out by controlling the residence time of said fibrous material in the powder and by constant control of the tension of said wick (81a) or said wicks when it (s) penetrate (s) into the fluidized bed.

Advantageously, the process of the invention is to the exclusion of any electrostatic process under voluntary charge. The term “sizing” designates the surface treatments applied to fibrous materials during their manufacture. It can also designate a fleeting pretreatment as a preamble to the pre-impregnation step, whether it is done directly in line with the impregnation or not. It can also designate a fleeting pretreatment as a preamble to the pre-impregnation step, whether it is done directly in line with the impregnation or not.

They are generally organic in nature (thermosetting or thermoplastic resin type) and very often formulated for the prepreg of the reinforcing fibers with polymers with a low melting point Tf or thermosetting with a low point Tg.

These sizes are also useful for protecting dry fibers from damage when in contact with a guide system.

Said fibrous material can therefore comprise up to 0.1% by weight of a material of an organic nature (such as thermosetting or thermoplastic resin) called size.

In the case of a fleeting pretreatment carried out by the impregnator, for example in the preamble to the pre-impregnation step of the reinforcing fibers, the size can be an organic liquid such as water, a low or high alcohol molecular weight (ethanol, methanol, isopropanol for example), a ketone (acetone etc ...) which will play the role of fleeting size; that is to say that it will be present a short time in contact with the fiber to allow its manipulation in the “dry” state (ie before the prepreg) and that it will then be extracted from the composite material so as not to disturb the final characteristics of the composite.

Advantageously, said wick (81 a) or said wicks is (are) not sized, in particular in the case of an amorphous thermoplastic resin having a high Tg or of a semi-crystalline resin with high melting point: in these cases l he size degrades when subjected to the high temperature of the transformation processes imposed by the nature of these resins.

This means that said wick (81 a) or said wicks is (are) either substantially devoid of sizing because the fibrous material has been de-sized beforehand or is devoid of sizing because the original fibrous material is not sized.

For de-sizing, several solutions exist: - Heating in a moisture-laden environment because generally the sizes are deposited in an aqueous base solution during the manufacture of the fibers because generally it is a prior treatment of the coils, otherwise it is necessary to put in line with the pre-impregnation process:

- thermal degradation

- a dip in a size solvent (water or other organic solvent). Advantageously, the mean diameter D50 by volume of the particles of thermoplastic polymer powder is from 30 to 300 μm, in particular from 50 to 200 μm, more particularly from 70 to 200 μm.

The expression "residence time in the powder" means the time during which the wick is in contact with said powder in the fluidized bed.

The inventors unexpectedly found that when a non-sized fibrous material is used for the prepreg step in a fluidized bed, the control of the residence time in the powder was no longer sufficient to prepreg the fibrous material. by the thermoplastic polymer matrix, in particular in a homogeneous manner with a powder rate (resin) well controlled and that the pre-impregnation step required the presence of one or more roll (s) filled in the fluidized bed with simultaneous control the tension of said fibrous material at the inlet of the fluidized bed.

There is a critical tension called Te which leads to fiber damage (fuzz) and a tension Te ’beyond which impregnation becomes impossible because the tension then blocks the development of the wick in the fluidized bed. Generally, in the case of non-sized fibers, Te is <to Te ’.

There is also a Tmin which is the voltage below which the twists appear.

Advantageously, the tension T of said wick (81 a) or of said wicks when it (s) enters the fluidized bed is less than Te.

Advantageously, the tension T of said wick (81 a) or of said wicks when it (s) enters the fluidized bed is greater than Tmin.

Advantageously, the tension T of said wick (81 a) or said wicks when it (s) penetrates (s) in the fluidized bed is less than Te and greater than Tmin. Throughout the description, the fibrous material after passage through the fluidized bed is called prepreg fibrous material and after heating and / or calendering, it is called impregnated fibrous material. The fiber content and porosity measurements are carried out on the impregnated fibrous material, and therefore after heating and / or calendering.

The term "homogeneous" means that the prepreg is uniform and that there are no dry fibers on the surface of the prepreg fibrous material.

Polymer matrix

The term “thermoplastic” or “thermoplastic polymer” is understood to mean a material which is generally solid at room temperature, which can be semi-crystalline or amorphous, and which softens during a temperature increase, in particular after passing its glass transition temperature (Tg). and flows at a higher temperature when it is amorphous, or which may exhibit a frank melting on passing its so-called melting temperature (Tf) when it is semi-crystalline, and which becomes solid again when the temperature decreases below its crystallization temperature (for a semi-crystalline) and below its glass transition temperature (for an amorphous).

The Tg and the Tf are determined by differential scanning calorimetry (DSC) according to the standard 1 1357-2: 2013 and 1 1357-3: 2013 respectively.

Regarding the polymer constituting the prepreg matrix of the fibrous material, it is advantageously a thermoplastic polymer or a mixture of thermoplastic polymers. This polymer or mixture of thermoplastic polymers is ground in powder form, in order to be able to use it in a device such as a tank, in particular in a fluidized bed.

The device in the form of a tank, in particular in a fluidized bed can be opened or closed. Optionally, the thermoplastic polymer or mixture of thermoplastic polymers further comprises carbonaceous fillers, in particular carbon black or carbonaceous nanofillers, preferably chosen from carbonaceous nanofillers, in particular graphenes and / or carbon nanotubes and / or carbon nanofibrils or their mixtures. These charges conduct electricity and heat, and therefore improve the lubrication of the polymer matrix when it is heated.

Optionally, said thermoplastic polymer comprises at least one additive, in particular chosen from a catalyst, an antioxidant, a thermal stabilizer, a UV stabilizer, a light stabilizer, a lubricant, a filler, a plasticizer, a flame-retardant agent, a nucleating agent , a chain extender and a dye or a mixture thereof. According to another variant, the thermoplastic polymer or mixture of thermoplastic polymers may also comprise liquid crystal polymers or cyclized poly (butylene terephthalate), or mixtures containing it, such as the CBT100 resin sold by the company CYCLICS CORPORATION. These compounds make it possible in particular to fluidify the polymer matrix in the molten state, for better penetration into the core of the fibers. Depending on the nature of the polymer, or mixture of thermoplastic polymers, used to produce the prepreg matrix, in particular its melting point, one or the other of these compounds will be chosen. The thermoplastic polymers forming part of the prepreg matrix of the fibrous material can be chosen from:

- polymers and copolymers of the family of aliphatic, cycloaliphatic polyamides (PA) or semi-aromatic PAs (also called polyphthalamides (PPA)),

- polyureas, in particular aromatics,

- polymers and copolymers of the acrylic family such as polyacrylates, and more particularly polymethyl methacrylate (PMMA) or its derivatives

- polymers and copolymers of the polyarylether ketone family (PAEK) such as poly (ether ether ketone) (PEEK), or polyarylether ketone ketones (PAEKK) such as poly (ketone ether ketone) (PEKK) or their derivatives,

- aromatic polyether imides (PEI),

- polyarylsulfides, in particular polyphenylene sulfides (PPS),

- polyarylsulfones, in particular polyphenylene sulfones (PPSU),

polyolefins, in particular polypropylene (PP);

- polylactic acid (PLA),

- polyvinyl alcohol (PVA),

- fluorinated polymers, in particular poly (vinylidene fluoride) (PVDF), or polytetrafluoroethylene (PTFE) or polychlorotrifluoroethylene (PCTFE), and mixtures thereof.

Advantageously, when said thermoplastic polymer is in a mixture, it is added in the form of powder obtained beforehand by “dry blend” or ground compound or directly in the tank in the form of “dry blend in situ”. Advantageously, it is added in the form of powder obtained beforehand by “dry blend” or directly in the tank in the form of “dry blend in situ” and the mixture is a mixture of PEKK and PEI.

Advantageously, when said polymer is a mixture of two polymers P1 and P2, the proportion by weight of polymer P1 and P2 is between 1 -99% and 99-1%. Advantageously, the PEKK / PEI mixture is comprised from 90-10% to 60-40% by weight, in particular from 90-10% to 70-30% by weight.

The thermoplastic polymer may correspond to the final non-reactive polymer which will impregnate the fibrous material or to a reactive prepolymer, which will also impregnate the fibrous material, but is capable of reacting on itself or with another prepolymer, depending on the end of the chain worn. by said prepolymer, after pre-impregnation, or even with a chain extender and in particular during heating at the level of the fittings in the oven and / or during the implementation of the tape in the final process for manufacturing the composite part.

According to a first possibility, said prepolymer can comprise or consist of, at least one reactive prepolymer (polyamide) carrying on the same chain (that is to say on the same prepolymer), of two terminal functions X 'and Y' respectively coreactive functions between them by condensation, more particularly with X 'and Y' being amine and carboxy or carboxy and amine respectively. According to a second possibility, said prepolymer can comprise or consist of, at least two polyamide prepolymers reactive with each other and each carrying two terminal functions X ′ or Y ′, identical (identical for the same prepolymer and different between the two prepolymers), said function X 'of a prepolymer being able to react only with said function Y' of the other prepolymer, in particular by condensation, more particularly with X 'and Y' being amine and carboxy or carboxy and amine respectively.

According to a third possibility, said prepolymer can comprise or consist of, at least one prepolymer of said thermoplastic polyamide polymer, carrying n terminal reactive functions X, chosen from: -NH2, -C02H and -OH, preferably NH2 and -C02H with n being 1 to 3, preferably 1 to 2, more preferably 1 or 2, more particularly 2 and at least one chain extender Y-A'-Y, with A 'being a hydrocarbon biradical, of non-polymeric structure, carrying of 2 identical reactive terminal functions Y, reactive by polyaddition with at minus a function X of said prepolymer a1), preferably of molecular mass less than 500, more preferably less than 400.

The number average molecular weight Mn of said final polymer of the thermoplastic matrix is preferably in a range from 10,000 to 40,000, preferably from 12,000 to 30,000. These Mn values can correspond to inherent viscosities greater than or equal to 0.8 such as determined in m-cresol according to ISO standard 307: 2007 but by changing the solvent (use of m-cresol instead of sulfuric acid and the temperature being 20 ° C).

Said reactive prepolymers according to the two options mentioned above have a number average molecular weight Mn ranging from 500 to 10,000, preferably from 1000 to 6000, in particular from 2500 to 6000.

The Mn are determined in particular by calculation from the rate of the terminal functions determined by potentiometric titration in solution and the functionality of said prepolymers. The Mn masses can also be determined by size exclusion chromatography or by NMR.

The nomenclature used to define polyamides is described in standard ISO 1874-1: 201 1 "Plastics - Polyamide materials (PA) for molding and extrusion - Part 1: Designation", in particular on page 3 (tables 1 and 2) and is well known to those skilled in the art.

The polyamide can be a homopolyamide or a copolyamide or a mixture of these.

Advantageously, the polymers constituting the matrix are chosen from Polyamides (PA), in particular chosen from aliphatic polyamides, in particular PA1 1 and PA12, cycloaliphatic polyamides, and semi-aromatic polyamides (polyphthalamides) optionally modified by urea units, and their copolymers, Polymethyl methacrylate (PPMA) and its copolymers, Polyether imides (PEI), Poly (phenylene sulfide) (PPS), Poly (phenylene sulfone) (PPSU), Polyetherketone ketone (PEKK), Polyetheretherketone (PEEK), fluorinated polymers such as poly (vinylidene fluoride) (PVDF).

For fluorinated polymers, it is possible to use a homopolymer of vinylidene fluoride (VDF of formula CH2 = CF2) or a copolymer of VDF comprising by weight at least 50% by mass of VDF and at least one other monomer copolymerizable with VDF. The VDF content must be greater than 80% by mass, or even better 90% by mass, to ensure good mechanical strength to the structural part, especially when it is subjected to thermal and chemical stresses. The comonomer can be a fluorinated monomer such as for example vinyl fluoride.

PAEK (PolyArylEtherKetone) such as polyether ketones PEK, poly (ether ether ketone) PEEK, poly (ether ketone) are advantageously used for structural parts which must withstand high temperatures, in addition to fluorinated polymers. ketone) PEKK, Poly (ketone ether ketone ketone ether) PEKEKK or high temperature glass transition PAs Tg).

Advantageously, said thermoplastic polymer is a polymer whose glass transition temperature is such that Tg> 80 ° C or a semi-crystalline polymer whose melting temperature Tf> 150 ° C.

Advantageously, said thermoplastic polymer is:

an aliphatic polyamide chosen from polyamide 6 (PA-6), polyamide 1 1 (PA- 1 1), polyamide 12 (PA-12), polyamide 66 (PA-66), polyamide 46 (PA-46 ), polyamide 610 (PA-610), polyamide 612 (PA-612), polyamide 1010 (PA-1010), polyamide 1012 (PA-1012), or a mixture thereof or a copolyamide of those - this,

a semi-aromatic polyamide, optionally modified by urea units, in particular a semi-aromatic polyamide of formula X / YAr, as described in EP1505099, in particular a semi-aromatic polyamide of formula A / XT in which A is chosen from a unit obtained from an amino acid, a unit obtained from a lactam and a unit corresponding to the formula (diamine in Ca). (Cb diacid), with a representing the number of carbon atoms in the diamine and b representing the number of carbon atoms in the diacid, a and b each being between 4 and 36, advantageously between 9 and 18, the unit (Ca diamine) being chosen from aliphatic diamines, linear or branched, cycloaliphatic diamines and alkylaromatic diamines and unit (Cb diacid) being chosen from aliphatic diacids, linear or branched, cycloaliphatic diacids and aromatic diacids ;

XT denotes a motif obtained from the polycondensation of a Cx diamine and terephthalic acid, with x representing the number of carbon atoms of the Cx diamine, x being between 6 and 36, advantageously between 9 and 18, in particular a polyamide of formula A / 6T, A / 9T, A / 10T or A / 1 1 T, A being as defined above, in particular a polyamide PA 6 / 6T, a PA 66 / 6T, a PA 6I / 6T, a PA MPMDT / 6T, PA MXDT / 6T, PA PA1 1 / 10T, PA 1 1 / 6T / 10T, PA MXDT / 10T, PA MPMDT / 10T, PA BACT / 10T, PA BACT / 6T , PA BACT / 10T / 6T, a PA 1 1 / BACT / 10T, PA 1 1 / BACT / 6T a PA 1 1 / MPMDT / 10T and a PA 1 1 / MXDT / 10T, and block copolymers, in particular polyamide / polyether (PEBA).

T corresponds to terephthalic acid, MXD corresponds to m-xylylene diamine, MPMD corresponds to methylpentamethylene diamine and BAC corresponds to bis (am inomethyl) cyclohexane.

Fibrous material:

As regards the fibers of which said fibrous material is made, these are in particular fibers of mineral, organic or vegetable origin.

As already said above, said fibrous material can therefore comprise up to 0.1% by weight of a material of an organic nature (such as thermosetting or thermoplastic resin) called size.

Advantageously, said wick (81 a) or said wicks is (are) not sized. This means that said wick (81 a) or said wicks is (are) either substantially devoid of size (s) because the fibrous material has previously been de-sized or is devoid of size (s) because the material original fibrous is not sized.

Among the fibers of mineral origin, mention may be made of carbon fibers, glass fibers, basalt fibers, silica fibers, or silicon carbide fibers for example. Among the fibers of organic origin, mention may be made of fibers based on a thermoplastic or thermosetting polymer, such as semi-aromatic polyamide fibers, aramid fibers or polyolefin fibers for example. Preferably, they are based on amorphous thermoplastic polymer and have a glass transition temperature Tg greater than the Tg of the polymer or mixture of thermoplastic polymer constituting the prepreg matrix when the latter is amorphous, or greater than the Tf of the polymer or mixture of thermoplastic polymer constituting the prepreg matrix when the latter is semi-crystalline. Advantageously, they are based on semi-crystalline thermoplastic polymer and have a melting temperature Tf greater than the Tg of the polymer or mixture of thermoplastic polymer constituting the prepreg matrix when the latter is amorphous, or greater than the Tf of polymer or mixture of thermoplastic polymer constituting the matrix prepreg when the latter is semi-crystalline. Thus, there is no risk of fusion for the organic fibers constituting the fibrous material during the impregnation by the thermoplastic matrix of the final composite. Among the fibers of vegetable origin, mention may be made of natural fibers based on flax, hemp, lignin, bamboo, notably spider silk, sisal, and other cellulosic fibers, in particular viscose. These fibers of vegetable origin can be used pure, treated or else coated with a coating layer, in order to facilitate the adhesion and the impregnation of the thermoplastic polymer matrix.

The fibrous material can also be a fabric, braided or woven with fibers.

It can also correspond to fibers with retaining threads.

These fibers of constitution can be used alone or in mixtures. Thus, organic fibers can be mixed with the mineral fibers to be pre-impregnated with thermoplastic polymer powder and form the pre-impregnated fibrous material.

The strands of organic fibers can have several grammages. They can also have several geometries. The fibers may be in the form of short fibers, which then make up the felts or nonwovens which may be in the form of strips, sheets, or pieces, or in the form of continuous fibers, which make up the 2D fabrics, the braids or unidirectional (UD) or non-woven fibers. The fibers constituting the fibrous material can also be in the form of a mixture of these reinforcing fibers of different geometries. Preferably, the fibers are continuous.

Preferably, the fibrous material consists of continuous fibers of carbon, glass or silicon carbide or a mixture thereof, in particular carbon fibers. It is used in the form of a wick or several wicks.

The impregnated materials, are also called “ready to use”, and are obtained from the prepreg fibrous material, after melting the powder or the powder mixture. In this type of impregnated material, the polymer or mixture of thermoplastic impregnation polymers is distributed so as to obtain a minimum of porosities, that is to say a minimum of voids between the fibers. Indeed, the presence of porosities in this type of material can act as stress concentration points, during a mechanical tensile stress for example, and which then form points of initiation of rupture of the impregnated fibrous material and weaken it mechanically. A reduction in porosity therefore improves the resistance mechanical and homogeneity of the composite material formed from these pre-impregnated fibrous materials.

Thus, in the case of so-called “ready-to-use” impregnated materials, the content of fibers in said impregnated fibrous material is from 45 to 65% by volume, preferably from 50 to 60% by volume, in particular from 54 to 60% by volume.

The measurement of the impregnation rate can be carried out by image analysis (use of a microscope or of a digital camera or camera, in particular), of a cross section of the ribbon, by dividing the surface of the ribbon impregnated by the polymer. by the total surface of the product (impregnated surface plus porosity surface). In order to obtain a good quality image it is preferable to coat the cut ribbon in its transverse direction in a standard polishing resin and to polish with a standard protocol allowing the observation of the sample under the microscope magnification at least 6 times .

Advantageously, the porosity rate of said impregnated fibrous material obtained after melting the powder present in the prepreg wick and impregnation at the heart of the fibers is between 0% and 30%, in particular from 1% to 10%, in particular of 1% to 5%.

The porosity rate corresponds to the closed porosity rate and can be determined either by electron microscopy or as the relative difference between the theoretical density and the experimental density of said pre-impregnated fibrous material as described in the examples part of the present invention.

Pre-impregnation step:

An example of a unit for implementing the manufacturing process is described in international application WO 2015/121583 and is shown in FIG. 1, with the exception of the tank (otherwise called pre-impregnation tank which in the case of l The invention comprises a fluidized bed provided with a grooved locking piece (FIG. 3) which can be a cylindrical grooved roller (FIG. 4)).

In FIGS. 1 to 9 in which the fitting piece or the roller are perpendicular to the fluidized bed, the groove is not visible. It is only in front view (Figures 2 and 4).

All the cylindrical rollers shown in Figures 1 to 9 are grooved.

The groove can be of any shape and has a width less than the width that the wick would have if the roller were smooth and cylindrical, of equal diameter the diameter at the bottom of the groove, under the same conditions of fluidization of the powder and tension of the wick.

The cylindrical roller can be fixed or in controlled rotation, that is to say not free. Several rollers can be present and if they are in controlled rotation, they can be co-rotating or counter-rotating.

The pre-impregnation step of the fibrous material is carried out by passing one or more wicks in a continuous pre-impregnation device, comprising a tank (20), comprising a fluidized bed (22) of polymer powder.

The polymer (s) or polymer powder is suspended in a gas G (air for example) introduced into the tank and circulating in the tank through a hopper 21. The wick (s) are circulated in this fluidized bed 22.

The tank may have any shape, in particular cylindrical or rectangular, in particular a rectangular parallelepiped or a cube, advantageously a rectangular parallelepiped.

The tank can be an open or closed tank. Advantageously, it is open. In the case where the tank is closed, it is then equipped with a sealing system so that the polymer powder cannot escape from said tank.

This pre-impregnation step is therefore carried out dry, that is to say that the thermoplastic polymer matrix is in the form of powder, in particular in suspension in a gas, in particular air, but cannot be in dispersion in a solvent or in water.

Each wick to be impregnated is unwound from a device (10) with reels (1 1) under the traction generated by cylinders (not shown). Preferably, the device (10) comprises a plurality of reels (1 1), each reel making it possible to unwind a wick to be impregnated. Thus, it is possible to prepreg several wicks of fibers simultaneously. Each reel (1 1) is provided with a brake (not shown) so as to apply tension to each wick of fibers. In this case, an alignment module (12) allows the strands of fibers to be arranged parallel to each other. In this way the strands of fibers cannot be in contact with one another, which makes it possible to avoid mechanical degradation of the fibers by friction between them.

The wick of fibers or the wicks of parallel fibers then pass into a tank (20), comprising in particular a fluidized bed (22), provided with a siphoning piece which is a cylindrical roller comprising several grooves (one per wick ) (23) in the case of FIG. 1. The wick of fibers or the wicks of parallel fibers then comes out of the tank after impregnation after checking the residence time in the powder and by constant control of the tension of said wick (81 a) or said wicks when it ( s) enters the fluidized bed.

Advantageously, the tension of said wick (81 a) or of said wicks when it (s) penetrates into the fluidized bed is up to 1000 g.

The tension of said wick can be measured either manually and intermittently at several points of the line using a tensiometer, or by means of strain gauges integrated in elements in contact with the wicks. Advantageously, the tension of said wick (81 a) or said wicks when it (s) penetrates into the fluidized bed is between 100 and 1000 g, in particular from 200 to 1000 g, more particularly from 300 to 850 g.

In one embodiment, said pre-impregnation step is carried out with simultaneous development of said wick (81 a) or said wicks between the inlet and the outlet of said fluidized bed (22).

Advantageously, the minimum width of said wick (81 a) or of said wicks is greater than the width of the groove of said sip.

The tension applied to the wick (or wicks) of fibers must be sufficient so that the minimum width of the free wick is greater than the width of the groove, so as to always fill the entire throat with the fiber wick . The minimum width of the wick means the width that the wick would have under the same conditions of tension and fluidization of the powder, on a smooth roller of the same diameter as that of the bottom of the grooves. This width can advantageously be measured by different methods, even on rollers completely immersed in the powder, such as with pressure sensors, position sensors (LVDT type) on a smooth roller and then be transposed to the use of a grooved roller whose groove width will be less than the minimum value recorded using the sensors.

The choice of the tension and throat width couple will be optimum when the tension will be minimum and the wicking of the wick will be good, however beyond 100g, preferably beyond 200g, at the outlet of the creel, so as to avoid training and / or passing twists.

The inventors have unexpectedly found that when a non-sized fibrous material is used for the prepreg step in a fluidized bed, the control of time of stay in the powder was no longer sufficient to impregnate the fibrous material with the thermoplastic polymer matrix, in particular at the core and in a homogeneous manner with a rate of powder (resin) well controlled and that the pre-impregnation step required the presence of one or more grooved fixtures, in particular one or more roller (s) engorged in the fluidized bed with simultaneous control of the tension of said fibrous material at the inlet of the fluidized bed.

They also found that the simultaneous control of the tension of said fibrous material at the inlet of the fluidized bed so that the minimum width of said wick is always greater than the width of the groove of said tying-up, in particular of said cylindrical grooved roller. allowed the impregnation of said fibrous material by the thermoplastic polymer matrix, in particular at the core and in a homogeneous manner with a well-controlled rate of powder (resin).

By sip of embarrassing piece, one understands any system on which the wick has the possibility of scrolling in the tank and which presents a groove. The fixture can have any shape from the moment it is engorged and the wick can pass through the throat.

Advantageously, the size of the grooves is just less than the minimum width of the fiber wick.

An example of a fitting piece, without restricting the invention to it, is detailed in Figure 3.

This impregnation is carried out in order to allow the polymer powder to penetrate into the heart of the wick of fiber and to adhere to the fibers sufficiently to support the transport of the powder wick out of the tank. The wick (s) pre-impregnated with powder, is (are) directed (s) then to a heating calendering device, with the possibility of preheating before calendering and possible post-calendering heating.

Optionally, this pre-impregnation step can be completed by a step of covering the wick or pre-impregnated wicks, just at the outlet of the tank (20) pre-impregnating with the powder in a fluidized bed (22). , and just before the step of shaping by calendering. For this, the exit airlock of the tank (20) (fluidized bed 22) can be connected to a covering device (30) which may include a covering angle head, as also described in patent EP0406067. The covering polymer can be identical to or different from the polymer powder in a fluidized bed. Preferably, it is of the same nature. Such a covering not only makes it possible to complete the step of prepregnating the fibers in order to obtain a final volume rate of polymer in the desired range and to avoid the presence on the surface of the prepreg wick, of a rate of fibers locally. too large, which would harm the welding of the tapes during the manufacture of the composite part, in particular for obtaining so-called “ready-to-use” fibrous materials of good quality, but also for improving the performance of the composite material obtained.

The process of the invention as indicated above is advantageously carried out by the dry route, with the exclusion of an electrostatic process under voluntary charge.

The expression "under voluntary load" means that a potential difference is applied between the fibrous material and the powder. The load is notably controlled and amplified. The grains of powders then permeate the fibrous material by attraction of the charged powder opposite the fiber. The powder can be electrically charged, negatively or positively, by various means (potential difference between two metal electrodes, mechanical friction on metal parts, etc.) and charge the fiber inversely (positively or negatively).

The method of the invention does not exclude the presence of electrostatic charges which could appear by friction of the fibrous material on the elements of the processing unit before or at the level of the tank but which are in any event of the involuntary charges.

Advantageously, the level of fibers in said impregnated fibrous material is from 45 to 65% by volume, preferably from 50 to 60% by volume, in particular from 54 to 60% by volume.

Below 45% of fibers, the reinforcement has no interest in terms of mechanical properties.

Above 65%, the process limits are reached and the mechanical properties are lost.

Advantageously, the fiber content in said impregnated fibrous material is between 50 and 60%, in particular from 54 to 60% by volume.

Advantageously, the residence time in the powder is from 0.01 s to 10 s, preferably from 0.1 s to 5 s, and in particular from 0.1 s to 3 s.

The residence time of the fibrous material in the powder is essential for controlling the level of resin, of said fibrous material. Below 0.1 s, the resin content will be too low for then, during the powder melting step, being able to impregnate the fibers at heart.

Beyond 10 s, the rate of polymer matrix impregnating the fibrous material is too high and the mechanical properties of the impregnated fibrous material will be poor.

Advantageously, the tank used in the process of the invention comprises a fluidized bed and said pre-impregnation step is carried out with simultaneous development of said wick or said wicks between the inlet and the outlet of said tank.

The expression "inlet of said tank" corresponds to the vertical tangent of the edge of the tank which comprises the fluidized bed.

The expression “exit from said tank” corresponds to the vertical tangent of the other edge of the tank which comprises the fluidized bed.

Depending on the geometry of the tank, the distance between the inlet and the outlet therefore corresponds to the diameter in the case of the cylinder, to the side in the case of a cube or to the width or length in the case of a rectangular parallelepiped. The flourishing consists in singling out as much as possible each filament constituting said wick of the other filaments which surround it in its closest space. It corresponds to the transverse spread of the wick.

In other words, the transverse spread or the width of the wick increases between the inlet of the fluidized bed (or of the tank comprising the fluidized bed) and the outlet of the fluidized bed (or of the tank comprising the fluidized bed) and thus allows a homogeneous prepreg of the fibrous material.

The fluidized bed can be opened or closed, in particular it is open.

Advantageously, the fluidized bed comprises at least one fitting piece, said wick or said wicks being in contact with part or all of the surface of said at least one fitting piece.

Figure 3 details a tank (20) comprising a fluidized bed (22) with a fitting piece, adjustable in height (82).

The wick (81 a) corresponds to the wick before impregnation which is in contact with part or all of the surface of said at least one mooring piece and therefore runs partially or totally on the surface of the mooring piece ( 82), said system (82) being immersed in the fluidized bed where impregnation takes place. Said wick then emerges from the tank (81 b) after checking the residence time in the powder.

Said wick (81a) can be in contact or not with the edge of the tank (83a) which can be a rotary or fixed roller or a parallelepipedic edge.

Advantageously, said wick (81a) is in contact or not with the edge of the tank (83a).

Advantageously, the edge of the tank (83b) is a roller, in particular cylindrical and rotary.

Said wick (81 b) can be in contact or not with the edge of the tank (83b) which can be a roller, in particular cylindrical and rotary or fixed, or a parallelepiped edge.

Advantageously, said wick (81b) is in contact with the edge of the tank (83b). Advantageously, the edge of the tank (83b) is a roller, in particular cylindrical and rotary.

Advantageously, said wick (81 a) is in contact with the edge of the tank (83a) and the edge of the tank (83b) is a roller, in particular cylindrical and rotary, and said wick (81 b) is in contact with the edge of the tank (83b), and the edge of the tank (83b) is a roller, in particular cylindrical and rotary.

Advantageously, said fitting piece is perpendicular to the direction of said wick or said wicks.

Advantageously, said development of said wick or said wicks is carried out at least at the level of said at least one fitting piece.

The development of the wick therefore takes place mainly at the level of the fitting piece but can also be carried out at the edge or edges of the tank if there is contact between the wick and said edge.

In another embodiment, said at least one fitting piece is a grooved cylindrical roller of convex, concave or cylindrical shape.

The convex shape is favorable to blooming while the concave shape is unfavorable to blooming although it is done nevertheless.

The expression "grooved cylindrical roller" means that the scrolling wick is supported partially or completely on the surface of said grooved cylindrical roller, which induces the blooming of said wick.

Advantageously, said at least one grooved cylindrical roller is of cylindrical shape and the percentage of development of said wick or said wicks between the inlet and the outlet of said fluidized bed is from 1% to 400%, preferably between 30% and 400% preferably between 30% and 150%, preferably between 50% and 150%. The blooming percentage is defined as (Lf-Li) / Li * 100, where Li and Lf are the widths before and after blooming. The development depends on the fibrous material used. For example, the flourishing of a carbon fiber material is much more important than that of a flax fiber.

Flourishing is also a function of the number of fibers or filaments in the wick, their average diameter and their cohesion.

The diameter of said at least one grooved cylindrical roller is from 3 mm to 500 mm, preferably from 10 mm to 100 mm, in particular from 20 mm to 60 mm. Below 3 mm, the deformation of the fiber induced by the grooved cylindrical roller is too great.

Advantageously, the grooved cylindrical roller is cylindrical and not grooved and in particular is metallic.

When the fitting piece is at least one grooved cylindrical roller, according to a first variant, a single grooved cylindrical roller is present in the fluidized bed and said impregnation is carried out at the angle formed by said wick or said wicks between the inlet of said grooved cylindrical roller and the vertical tangent to said grooved cylindrical roller.

The angle formed by said wick or said wicks between the inlet of said grooved cylindrical roller and the vertical tangent to said grooved cylindrical roller allows the formation of an area in which the powder will concentrate thus leading to a "wedge effect" which with the simultaneous development of the wick by said grooved cylindrical roller allows a prepreg on a larger width of wick and therefore an improved prepreg compared to the techniques of the improved prior art. The coupling with the controlled residence time then allows a homogeneous prepreg.

Advantageously, the angle is included from 0 to 89 °, preferably 5 ° to 85 °, preferably from 5 ° to 45 °, preferably from 5 ° to 30 °.

However, an angle of 0 to 5 ° is likely to generate risks of mechanical stress, which will lead to breakage of the fibers and an angle of 85 to 89 ° does not create enough mechanical effort to create the "corner effect". A value of the angle equal to 0 ° therefore corresponds to a vertical fiber. It is obvious that the height of the cylindrical grooved cylindrical roller is adjustable, thus making it possible to position the fiber vertically.

It would not go beyond the scope of the invention if the wall of the tank were pierced so as to be able to allow the wick to exit.

Advantageously, the edge of the tank (83a) is equipped with a roller, in particular cylindrical and rotary, on which said strand or said strands pass, thereby leading to prior blooming.

Advantageously, one or more embarrassments are present downstream of the tank comprising the fluidized bed at the level of which or which the blooming is initiated. Advantageously, the blooming is initiated at the level of said above-mentioned interruptions and continues at the level of the edge of the tank (83a).

The blooming is then maximum after passage at the level of the grooved cylindrical roller (s).

FIG. 4 describes an embodiment, without being limited to this, with a single grooved cylindrical roller, with a tank (20) comprising a fluidized bed (22) in which a single cylindrical grooved cylindrical roller is present and showing the 'angle ai _.

The arrows on the fiber indicate the direction of travel of the fiber.

Advantageously, the level of said powder in said fluidized bed is at least situated at the mid-height of said grooved cylindrical roller.

It is quite obvious that the “corner effect” caused by the angle favors the prepreg on one side, but the development of said wick obtained thanks to the grooved cylindrical roller also makes it possible to have a prepreg on the other side of said wick. In other words, said prepreg is favored on one face of said wick or said wicks at the angle formed by said wick or said wicks between the inlet of said at least one cylindrical grooved roll Ri and the vertical tangent to the roll cylindrical grooved Ri but the blooming also makes it possible to prepreg the other face.

The angle is as defined above.

According to a second variant, when the fixing piece is at least one grooved cylindrical roller, then two grooved cylindrical rollers Ri and R2 are in said fluidized bed and said prepreg is carried out at the angle formed by said wick or said wicks between the inlet of said grooved cylindrical roller Ri and the vertical tangent to said grooved cylindrical roller Ri and / or at the angle 02 formed by said wick or said wicks between the inlet of said grooved cylindrical roller R2 and the vertical tangent to said gorged cylindrical roller R2, said gorged cylindrical roller Ri preceding said gorged cylindrical roller R2 and said wick or said wicks being able to pass above (FIG. 5 and 6) or below (Figure 7 and 8) of the R2 roller.

Advantageously, the two grooved cylindrical rollers are of identical or different shape and chosen from a convex, concave or cylindrical shape.

Advantageously, the two cylindrical grooved rollers are identical and cylindrical and in particular metallic.

The diameter of the two grooved cylindrical rollers can also be the same or different and is as defined above.

Advantageously, the diameter of the two grooved cylindrical rollers is identical. The two grooved cylindrical rollers Ri and R2 may be at the same level with respect to each other and with respect to the bottom of the tank (FIGS. 6 and 7) or offset with respect to each other and with respect to at the bottom of the tank, the height of the grooved cylindrical roller Ri being greater than or less than that of the grooved cylindrical roller R2 relative to the bottom of the tank (Figures 5 and 8).

Advantageously, when the two rollers are at different heights and the wick passes over the roller R2, then 02 is included from 0 to 90 °.

Advantageously, said prepreg is therefore carried out at the angle formed by said wick or said wicks between the inlet of said grooved cylindrical roller Ri and the vertical tangent to said cylindrical grooved roller on one face of said wick and at the level of the angle 02 formed by said wick or said wicks between the entry of said grooved cylindrical roller R2 and the vertical tangent to said cylindrical grooved roller R2 on the opposite face of said wick which is obtained by passing above the roller R2.

Advantageously, said wick in this embodiment is subject to blooming at each angle at and 02.

FIG. 6 describes an embodiment, without being limited to this, with two engorged cylindrical rollers Ri and R2 _, Ri preceding R2, with a tank (20) comprising a fluidized bed (22) in which the two engorged cylindrical rollers cylindrical, at the same level and side by side, are present and showing the case where said one or more wicks emerge between said cylindrical grooved rollers Ri and R2. In this case, the angle 0 ₂ is equal to 0 and said one or more wicks pass over the roller R ₂ .

The arrows on the fiber indicate the direction of travel of the fiber.

Alternatively, said wick or said wicks scroll (s) at the inlet between said cylindrical grooved rollers Ri and R ₂ and comes out (ent) after having been in contact with part or all of the surface of said cylindrical grooved roller R _2.

Advantageously, said wick or said wicks are (are) in contact at the input with part or all of the surface of said cylindrical grooved roller Ri and spring (ent) outside the cylindrical grooved roller R ₂ after being in contact with part or all of the surface of said grooved cylindrical roller R ₂ , under the roller R ₂ , the angle 0 ₂ being formed by said drill bit (s) between the inlet of said cylindrical grooved roller R ₂ and the vertical tangent to said roller cylindrical grooved R ₂ . In this case, the angle 0 ₂ = 90 °.

Said prepreg is therefore carried out at the angle formed by said wick or said wicks between the inlet of said grooved cylindrical roller Ri and the vertical tangent to said cylindrical grooved roller on one face of said wick and at level 'angle 0 ₂ formed by said wick or said wicks between the inlet of said cylindrical grooved roller R ₂ and the vertical tangent to said cylindrical grooved roller R ₂ on the same face of said wick but the blooming also makes it possible to pre-impregnate the other face.

Advantageously, said wick in this embodiment is subject to blooming at each angle at and 0 ₂ .

FIG. 7 shows an exemplary embodiment with two cylindrical grooved rollers Ri and R ₂ at the same level relative to each other.

According to another embodiment of the second variant, when two cylindrical grooved rollers are present then the distance between the two cylindrical grooved rollers Ri and R ₂ is 0.15 mm at the length equivalent to the maximum dimension of the tank, preferably between 10mm and 50mm and the height difference between the two grooved cylindrical rollers Ri and R ₂ is between 0 and the height corresponding to the maximum height of the tank subtracted from the diameters of the two grooved cylindrical rollers, preferably between 0, 15mm at the height corresponding to the maximum height of the tank subtracted from the diameters of the two grooved cylindrical rollers, more preferably at a height difference between 10mm and 300mm, R ₂ being the upper grooved cylindrical roller.

Advantageously, when two siphoned cylindrical rollers are present and at the same level with one another, the level of said powder in said fluidized bed is at least located at the mid-height of said two siphoned cylindrical rollers.

FIG. 8 describes an embodiment, without being limited to this, with two engorged cylindrical rollers Ri and R ₂ , Ri preceding R ₂ , with a tank (20) comprising a fluidized bed (22) in which two cylindrical rollers cylindrical sips at different levels are present and showing the angle at and 0 _2.

The diameter of the cylindrical grooved rollers Ri and R ₂ is presented as identical in FIGS. 5, 6, 7 and 8 but the diameter of each cylindrical grooved cylindrical roller can be different, the diameter of the cylindrical grooved roller Ri being able to be greater or less than that of the grooved cylindrical roller R ₂ in the range as defined above.

Advantageously, the diameter of the two grooved cylindrical rollers is identical. It would not go beyond the scope of the invention if the grooved cylindrical roller Ri was greater than the grooved cylindrical roller R ₂ .

According to a third variant, when two cylindrical grooved rollers are present and at different levels, then at least one third cylindrical grooved roller R ₃ is also present and located between the cylindrical grooved rollers Ri and R ₂ in the height direction ( figure 9).

Advantageously, said wick or said wicks are (are) in contact at the input with part or all of the surface of said grooved cylindrical roller Ri then with part or all of the surface of said cylindrical grooved roller R ₃ and comes out (ent) after have been in contact with part or all of the surface of said grooved cylindrical roller R ₂ .

Advantageously, said prepreg is carried out on one face of said wick or said wicks at the angle formed by said wick or said wicks between the inlet of said at least one grooved cylindrical roller Ri and the vertical tangent to the cylindrical roller grooved Ri as well as at the angle 0 ₃ formed by said drill bit (s) and the vertical tangent to the grooved cylindrical roller R ₃ and on the other face only at the angle 0 ₂ formed by said drill bit or said wicks and the vertical tangent to the grooved cylindrical roller R ₂ . Advantageously, when two grooved cylindrical rollers are present at different levels and at least one third grooved cylindrical roller R3 is also present, then the angle 02 formed by said wick or said wicks between the inlet of said at least one roller cylindrical grooved R2 and the vertical tangent to said cylindrical grooved roller R2, is included from 180 ° to 45 °, in particular from 120 ° to 60 °.

Advantageously, the angle 03 is comprised from 0 ° to 180 °, advantageously from 45 ° to 135 °.

FIG. 9 describes an embodiment, without being limited thereto, with a tank (20) comprising a fluidized bed (22) with two cylindrical rollers engorged Ri and R2, Ri preceding R2, and a third cylindrical roller engorged R3 and showing the angles ai _, 02 and 03.

The diameter of the cylindrical grooved rollers Ri, R2 and R3 is presented as identical in FIG. 9 but the diameter of each cylindrical grooved cylindrical roller can be different, or two cylindrical grooved rollers can have the same diameter and the third a different diameter greater or lower, in the range as defined above.

Advantageously, the diameter of the three engorged cylindrical rollers is identical. Advantageously, in this third variant, a second control of the development of said wick or said wicks is carried out at the level of the grooved cylindrical roller R3 and a third control of the development is carried out at the level of the grooved cylindrical roller R3.

The residence time in this third variant is as defined above.

Advantageously, in this third variant, the level of said powder in said fluidized bed is at least located at the mid-height of said grooved cylindrical roller R2. It would not go beyond the scope of the invention if in this third variant, said wick or said wicks is (are) in contact with a part or all of the surface of said grooved cylindrical roller Ri and then with part or all from the surface of said grooved cylindrical roller R2 and comes out after being in contact with part or all of the surface of said cylindrical grooved roller R3 ·

According to an advantageous embodiment, the present invention relates to a process as defined above, characterized in that a single thermoplastic polymer matrix is used and the thermoplastic polymer powder is fluidizable. The term “fluidizable” means that the air flow rate applied to the fluidized bed is between the minimum fluidization flow rate (Umf) and the minimum bubbling flow rate (Umf) as shown in FIG. 12.

Below the minimum fluidization rate, there is no fluidization, the particles of polymer powder fall into the bed and are no longer in suspension and the process according to the invention cannot operate.

Above the minimum bubbling rate, the powder particles fly away and the composition of the constant fluidized bed can no longer be kept constant.

Advantageously, the volume diameter D90 of the particles is between 50 and 500 μm, advantageously from 120 to 300 μm.

Advantageously, the volume diameter D10 of the particles is from 5 to 200 μm, advantageously from 35 to 100 μm.

Advantageously, the diameter by volume of the powder particles is included in the ratio D90 / D10, that is to say comprised from 1.5 to 50, advantageously from 2 to 10.

Advantageously, the mean diameter D50 by volume of the particles of thermoplastic polymer powder is from 30 to 300 μm, in particular from 50 to 200 μm, more particularly from 70 to 200 μm.

The particle volume diameters (D10, D50 and D90) are defined according to ISO 9276: 2014.

The "D50" corresponds to the volume average diameter, that is to say the value of the particle size which divides the population of particles examined exactly in two. The "D90" corresponds to the value at 90% of the cumulative curve of the particle size distribution by volume.

The "D10" corresponds to the corresponds to the size of 10% of the volume of the particles. According to another embodiment of the method according to the invention, a creel is present before the tank comprising a fluidized bed for controlling the tension of said wick or said wicks at the inlet of the tank comprising a fluidized bed.

Optionally, in the method according to the invention, one or more embarrassments are present after the tank comprising the fluidized bed.

Optionally, grooved rollers at the inlet and outlet of the tank containing the fluidized bed can be used.

Heating stage

In another embodiment, the present invention relates to a method as defined above, characterized in that it further comprises at least one step of heating of the thermoplastic matrix allowing the melting or maintaining of the melting of said thermoplastic polymer after prepreg,

said at least one heating step being carried out by means of at least one connecting piece (E) conductive or not of heat and at least one heating system, with the exception of a heating calender,

said wick or said wicks being in contact with part or all of the surface of said at least one mooring piece (E) and running partially or completely over the surface of said at least one mooring piece (E) at heating system level.

It would not be departing from the scope of the invention if the mooring piece (E) was positioned in an oven comprising a heating system, for example by IR but that said mooring piece was not positioned exactly under the elements heating for example by IR. We would not go beyond the invention if the oven had a convection heating mode and an IR heating system.

We would not depart from the invention either if said docking piece (E) placed in this oven or in the environment of this oven, was equipped with an independent heating means as a resistor for heating said room d 'embarrage (E), independently for example of the radiation of IR lamps and the natural convection of the oven and that, taking into account the speed of the line, the polymer present in the ribbons or wicks is still in the molten state when it comes into contact with said lashing part. The height between the heating system and the fittings is from 1 to 100 cm, preferably from 2 to 30 cm, in particular from 2 to 10 cm.

A first heating step can be immediately consecutive to the pre-impregnation step or other steps can take place between the pre-impregnation step and the heating step.

However, the first stage of implementation by a heating system provided with at least one locking piece (E) does not correspond to a heating calender, and is always carried out before the calendering stage which is necessary to smooth and format the ribbon.

Advantageously, said first heating step is immediately consecutive to the pre-impregnation step. The expression "immediately consecutive" means that there is no intermediate step between the pre-impregnation step and said heating step.

Advantageously, a single heating step is carried out, immediately following the pre-impregnation step. Advantageously, said at least one heating system is chosen from an infrared lamp, a UV lamp and convection heating if the interlocking piece is heat conductive.

The fibrous material being in contact with the fixture (s) in the heating system, and the fixture being conductive, the heating system is therefore also carried out by conduction.

Advantageously, said at least one heating system is chosen from an infrared lamp.

Advantageously, if the fitting is not heat conductive, said at least one heating system is chosen from microwave heating, laser heating, and high frequency heating (HF).

The non-heating and non-conductive embedding piece (E) does not absorb the wavelength of the microwave, laser or HF heating system.

Advantageously, said at least one heating system is chosen from microwave heating.

Advantageously, said at least one fitting piece (E) is a compression roller R’i of convex, concave or cylindrical shape.

It should be noted that the compression rollers corresponding to the embedding pieces (E) or those used for the pre-impregnation step may be identical or different, whether in terms of material or shape and its characteristics (diameter, length, width, height ... depending on the shape).

The at least one fitting piece (E) can also be an alternation of convex and concave shape. In this case, the scrolling of the wick on a compression roller of convex shape causes the blooming of said wick then the scrolling of the wick on a compression roller of concave shape causes the retraction of the wick and so on allowing if need to improve the homogeneity of the impregnation, especially at heart.

The expression "compression roller" means that the scrolling wick is supported partially or completely on the surface of said compression roller, which induces the blooming of said wick.

The rollers can be controlled rotation or fixed.

They are full and the back of the throat may be smooth or streaked. Shaping step

Optionally, a step of shaping the lock or said parallel locks of said impregnated fibrous material is carried out.

A calendering system as described in WO 2015/121583 can be used. Advantageously, it is carried out by calendering by means of at least one heating calender in the form of a single unidirectional ribbon or ply or of a plurality of parallel unidirectional ribbons or ply with, in the latter case, said heating calender comprising a plurality of grooves calendering, preferably up to 200 calendering grooves, in accordance with the number of said ribbons and with a pressure and / or a spacing between the rollers of said calender regulated by a controlled system.

This step is always carried out after the heating step if there is only one or between the first heating step and the second heating step when the two coexist.

Advantageously, the calendering step is carried out by means of a plurality of heating calenders, mounted in parallel and / or in series with respect to the direction of travel of the strands of fibers.

Advantageously, said (or said) heating calender (s) comprises (include) a heating system integrated by induction or by microwaves, preferably by microwaves, coupled to the presence of carbonaceous fillers in said thermoplastic polymer or mixture of polymers thermoplastics.

According to another embodiment, a belt press is present between the heating system and the calender.

According to yet another embodiment, a heating die is present between the heating system and the grille.

According to another embodiment, a belt press is present between the heating system and the calender and a heating die is present between the band press and the calender.

Advantageously, the step of shaping said wick or said parallel wicks of said pre-impregnated fibrous material, by calendering by means of at least one heating calender in the form of a single unidirectional ribbon or sheet or of a plurality of ribbons or unidirectional parallel sheets with, in the latter case, said heating calender comprising a plurality of calendering grooves, of preferably up to 300 calendering grooves, in accordance with the number of said ribbons and with a pressure and / or a spacing between the rollers of said calender regulated by a controlled system.

In one embodiment, said heating grille (s) is (are) coupled to an additional heating device, located before and / or after said (each) grille, in particular a device microwave or induction heating coupled to the presence of carbonaceous charges in said polymer or in said mixture of polymers, or an infrared IR or laser heating device or by direct contact with another heat source such as a flame or a hot gas .

In another embodiment, said pre-impregnation step (s) is (are) supplemented by a step of covering said single wick or said plurality of parallel wicks after pre-impregnation with the powder, said covering step being carried out before said calendering step, with a molten thermoplastic polymer, which may be identical to or different from said polymer in the form of powder in a fluidized bed, said molten polymer preferably being of the same nature as said polymer in powder form fluidized bed, preferably with said covering being effected by extrusion at a right angle relative to said single wick or to said plurality of parallel wicks.

According to another aspect, the present invention relates to a unidirectional ribbon or web of pre-impregnated fibrous material, in particular ribbon or web wound on a reel, characterized in that it (it) is obtained by a process such as defined above.

Advantageously, the ribbon or the sheet has a width (I) and a thickness (ep) suitable for removal by robot in the manufacture of three-dimensional parts, and preferably has a width (I) of at least 5 mm and up to 600mm, preferably between 50 and 600 mm and even more preferably between 50 and 300mm.

Removal by robot can be carried out with or without slitting.

Advantageously, the thermoplastic polymer of the ribbon or the sheet is a polyamide chosen from, in particular, an aliphatic polyamide as chosen PA 6, PA 1 1, PA 12, PA 66, PA 46, PA 610, PA 612, PA 1010, PA 1012 , PA 1 1/1010 or PA 12/1010 or a semi-aromatic polyamide such as PA MXD6 and PA MXD10 or chosen from PA 6 / 6T, PA 66 / 6T, PA 6I / 6T, PA MPMDT / 6T, PA MXDT / 6T, PA PA1 1 / 10T, PA 1 1 / 6T / 10T, PA MXDT / 10T, PA MPMDT / 10T, PA BACT / 10T, PA BACT / 6T, PA BACT / 10T / 6T, PA BACT / 6T / 1 1 a PA 1 1 / BACT / 10T, a PA 1 1 / MPMDT / 10T and a PA 1 1 / MXDT / 10T, a PVDF, a PEEK, PEKK and a PEI or a mixture of these.

According to another aspect, the present invention relates to the use of the method as defined above, for the manufacture of ribbons or calibrated plies suitable for the production of three-dimensional composite parts, by automatic removal of said ribbons or tablecloths using a robot.

According to another aspect, the present invention relates to the use of the ribbon or the sheet of impregnated fibrous material, as defined above, in the manufacture of three-dimensional composite parts.

Said impregnated tape is therefore obtained from a prepreg tape after the heating step described above.

Advantageously, said manufacture of said composite parts relates to the fields of transport, in particular automobile, oil and gas, in particular offshore, gas storage, civil or military aeronautics, aerospace, nautical, rail; renewable energies, in particular wind, tidal, energy storage devices, solar panels; thermal protection panels; sports and recreation, health and medical, security and electronics.

According to yet another aspect, the present invention relates to a three-dimensional composite part, characterized in that it results from the use of at least one unidirectional ribbon of impregnated fibrous material as defined above.

Advantageous embodiments of the process of the invention

Advantageously, the fibrous material is chosen from carbon fiber and glass fiber. Advantageously, the thermoplastic polymer used to impregnate the carbon fiber is chosen from a polyamide, in particular an aliphatic polyamide such as PA 1 1, PA 12, PA 1 1/1010 or PA 12/1010, or a semi-aromatic polyamide, particular a PA MXD6 and a PA MXD10 or selected from PA 6 / 6T, a PA 66 / 6T, a PA 6I / 6T, a PA MPMDT / 6T, a PA MXDT / 6T, a PA PA1 1 / 10T, a PA 1 1 / 6T / 10T, PA MXDT / 10T, PA MPMDT / 10T, PA BACT / 10T, PA BACT / 6T, PA BACT / 10T / 6T, PA BACT / 6T / 1 1, PA 1 1 / BACT / 10T, a PA 1 1 / MPMDT / 10T and a PA 1 1 / MXDT / 10T, a PVDF, a PEEK, PEKK and a PEI or a mixture thereof. Advantageously, the thermoplastic polymer used to impregnate the glass fiber is chosen from a polyamide, in particular an aliphatic polyamide such as PA 1 1, PA 12, PA 1 1/1010 or PA 12/1010, or a semi-aromatic polyamide, particular a PA MXD6 and a PA MXD10 or selected from PA 6 / 6T, a PA 66 / 6T, a PA 6I / 6T, a PA MPMDT / 6T, a PA MXDT / 6T, a PA PA1 1 / 10T, a PA 1 1 / 6T / 10T, PA MXDT / 10T, PA MPMDT / 10T, PA BACT / 10T, PA BACT / 6T, PA BACT / 10T / 6T, PA BACT / 6T / 1 1, PA 1 1 / BACT / 10T, a PA 1 1 / MPMDT / 10T and a PA 1 1 / MXDT / 10T, a PVDF, a PEEK, PEKK and a PEI or a mixture thereof. Advantageously, the content of fibers in said fibrous material, consisting of carbon fiber or glass, impregnated is between 45 and 65% by volume, preferably from 50 to 60% by volume, in particular from 54 to 60% by volume. .

Description of the figures

FIG. 1 presents a diagram of a unit for implementing the process for manufacturing a prepreg fibrous material according to the invention.

Figure 2 shows a sectional diagram of two rollers constituting a calender as used in the unit of Figure 1.

FIG. 3 details a tank (20) comprising a fluidized bed (22) with a siphoned interlocking piece, adjustable in height (82). The edge of the tank inlet is equipped with a rotary roller 83a on which the wick 81 a runs and the edge of the tank outlet is equipped with a rotary roller 83b on which the wick 81 b travels.

The roller being perpendicular to the direction of travel of the drill bit, the groove of the roller is only visible when viewed from the front or from above.

FIG. 4 presents an embodiment with a single grooved cylindrical roller, with a tank (20) comprising a fluidized bed (22) in which a single cylindrical grooved cylindrical roller is present and showing the angle a-i.

The arrows on the fiber indicate the direction of travel of the fiber. The roller being perpendicular to the direction of travel of the wick, the groove of the roller is only visible in front or top view.

FIG. 5 shows an embodiment, without being limited to this, with two cylindrical grooved rollers Ri and R2 _, Ri preceding R2, with a tank (20) comprising a fluidized bed (22) in which the two cylindrical grooved rollers cylindrical are at different heights from the bottom of the tank (R2 at a height H2 above Ri at a height H1) are present and showing the angle at and a _2.

The arrows at the fiber wick indicate the direction of travel of the wick.

FIG. 6 presents an exemplary embodiment with a tank (20) comprising a fluidized bed (22) in which the two cylindrical grooved rollers Ri and R2 are cylindrical, at the same level with respect to each other and side side by side and showing the angle ai, and the angle 02 = 0 ° and the wick passing between the 2 rollers)

FIG. 7 shows an exemplary embodiment with a tank (20) comprising a fluidized bed (22) in which the two siphoned cylindrical rollers Ri and R2 are cylindrical, at the same level with respect to each other and side side by side and showing the angle ai, and the angle 02 = 90 ° and the wick passing below R2.

FIG. 8 shows an exemplary embodiment with a tank (20) comprising a fluidized bed (22) in which two cylindrical cylindrical grooved rollers Ri and R2, Ri preceding R2, at different levels are present and showing the angle in and 02 and the wick passing under the roller R2.

FIG. 9 shows an embodiment with a tank (20) comprising a fluidized bed (22) with two cylindrical grooved rollers Ri and R2, Ri preceding R2, and a cylindrical grooved roller R3 and showing the angles at, 02 and 03.

Figure 10 presents a photo taken with the scanning electron microscope of a sectional view of a ¼ ”carbon fiber ribbon, obtained from a wick of 12K carbon fibers homogeneously pre-impregnated with a polyamide powder PA MPMDT / 10T (67/33 mol%) of D50 = 1 15pm according to the method of WO20181 15736 (as described in Comparative Example 1) with an unroasted roller (smooth) and with a low tension at the inlet of the 800g fluidized bed.

The fibers are then impregnated to the core by said resin after melting said powder present in said pre-impregnated wick, after heating and passing through a series of tying-up, followed by calendering, to form said final ribbon. The image analysis made on a number of images statistically representative of said ribbon, gives a porosity rate of 3% excluding the edges of the ribbon.

FIG. 11 presents the evolution of the mass percentage of MPMDT / 10T impregnated in the wick as a function of time in Comparative Example 1.

Figure 12 presents a photo taken under the scanning electron microscope of a sectional view of a ¼ ”carbon fiber ribbon, obtained from a wick of 12K carbon fibers pre-impregnated homogeneously with a polyamide PA MPMDT / 10T powder (67/33 mol%) of D50 = 1 15pm according to the method of the invention and as described in Comparative Example 2), that is to say with a grooved roller and with a low voltage at the inlet of the fluidized bed of 800g. The fibers are then impregnated to the core by said resin after melting of said powder present in said pre-impregnated wick, after heating and passing through a series of ties, followed by calendering, to form said final ribbon.

after heating and calendering) with a grooved roller with a low tension at the inlet of the 800g fluidized bed of Example 2.

The image analysis gives a porosity rate of 1.5% excluding the edges of the tape. FIG. 13 shows the evolution of the mass percentage of MPMDT / 10T impregnated in the wick as a function of the time of Example 2.

Figure 14 shows the fluidization as a function of the air flow. The air flow applied to the fluidized bed must be between the minimum fluidization flow (Umf) and the minimum bubbling flow (Umf)

The following examples illustrate, without limitation, the scope of the invention.

Comparative Example 1: General Procedure for Preimpregnating a Fibrous Material (Non-Sized Carbon Fiber) with an MPMDT / 10T Powder

(67/33 mol%) in a fluidized bed with a single smooth cylindrical roller and with a low tension of the wick (800q) at the entry of the fluidized bed.

The following procedure was carried out:

- A smooth cylindrical roller in the tank (L = 500 mm, W = 500mm, H = 600mm), diameter 25 mm.

- Tension of the wick at the entry of the fluidized bed: 800g

- 0.3 sec residence time in the powder

- Angle of 25 ° - Flourishing about 100% (a width multiplied by 2) for a wick in carbon fiber of Hexcel 12K AS4.

- D50 = 1 15 pm, (D10 = 49pm, D90 = 207pm) for the powder of MPMDT / 10T.

- edge of the tank fitted with a fixed roller.

The fibrous material (12K carbon fiber wick) was homogeneously pre-impregnated with an MPMDT / 10T polyamide powder with a particle size distribution defined above according to this operating mode and the ribbon obtained from this pre-impregnated wick, after melting the powder and passing through a series of tying-up followed by a calendering is presented in figure 10 in order to obtain a ¼ ”tape.

The results obtained show that the level of impregnated polymer is not stable over time (see FIG. 11). The wick width in and out of the fluid bed varies.

EXAMPLE 2 General Procedure for Preimpregnating a Fibrous Material (Carbon Fiber Not Sized) with a Polyamide Powder in a Fluidized Bed with a Single Cylindrical Roller Gorged with a Low Tension of the Wick at the Entry of the Fluidized Bed (800q )

The following procedure was carried out:

- A cylindrical roller grooved in the tank (L = 500 mm, W = 500mm, H = 600mm), diameter 25 mm at the bottom of the throat, 5mm throat depth.

- Tension of the wick at the entry of the fluidized bed: 800g

- 0.3 sec residence time in the powder

- Angle of 25 °

- Flourishing approximately 100% (i.e. a width multiplied by 2) for a non-sized carbon fiber wick of Hexcel 12K AS4

- D50 = 1 15 pm, (D10 = 49pm, D90 = 207pm) for the powder of MPMDT / 10T (67/33% molar).

- edge of the tank fitted with a fixed roller.

The fibrous material (12K carbon fiber wick) was homogeneously pre-impregnated with an MPMDT / 10T polyamide powder with a particle size distribution defined above according to this operating mode and the ribbon obtained from this wick impregnated, after melting the powder and passing through a series of tying-up followed by a calendering is presented in figure 12 to obtain a ¼ ”tape.

It is observed that in the presence of a grooved roller in the powder, and using a low tension for the fiber at the inlet of the fluid bed, the rate of impregnated polymer is stable over time (cf. FIG. 13).

In addition, we do not observe any fuzz created before pre-impregnation due to the low tension applied to the fiber at the inlet of the fluid bed, thus promoting the good health of the tape.

This demonstrates the effectiveness of the pre-impregnation process with a dry powder in a fluidized bed with a cylindrical roller grooved with a non-sized fiber and control of the residence time and the tension in the powder as opposed to a smooth roller.

Example 3: Determination of the porosity rate by image analysis

The porosity was determined by image analysis on a ½ ”carbon fiber wick impregnated with MPMDT / 10T). It is 5%.

Example 4: Determination of the porosity rate the relative difference between theoretical density and experimental density (general method)

a) The required data are:

The density of the thermoplastic matrix

Fiber density

The grammage of the reinforcement:

• linear mass (g / m) for example for a ¼ inch tape (from a single rowing)

• areal mass (g / m ² ) for example for a wider tape or a fabric b) Measures to be carried out:

The number of samples must be at least 30 for the result to be representative of the material studied.

The measures to be carried out are:

The size of the samples taken:

o Length (if known linear mass)

o Length and width (if known areal mass).

The experimental density of the samples taken: o Mass measurements in air and water.

The measurement of the fiber content is determined according to ISO 1172: 1999 or by thermogravimetric analysis (ATG) as determined for example in the document B. Benzler, Applikationslabor, Mettler Toledo, Giesen, UserCom 1/2001. The measurement of the carbon fiber content can be determined according to ISO 14127: 2008.

Determination of the theoretical mass fiber content:

a) Determination of the theoretical mass fiber content:

With

mid the linear mass of the tape,

L the length of the sample and

Measure the mass of the sample measured in the air.

The variation in the mass content of fibers is assumed to be directly linked to a variation in the matrix rate without taking into account the variation in the quantity of fibers in the reinforcement. b) Determination of the theoretical density:

With dm and df the respective densities of the matrix and the fibers.

The theoretical density thus calculated is the density accessible if there is no porosity in the samples. c) Evaluation of the porosity:

The porosity is then the relative difference between theoretical density and experimental density.

Claims

1. A method of manufacturing a prepreg fibrous material comprising a fibrous material made of continuous fibers and at least one thermoplastic polymer matrix, characterized in that said prepreg fibrous material is produced in a single unidirectional ribbon or in a plurality of unidirectional parallel ribbons and in that said method comprises a step of prepregnation, in particular homogeneous, of said fibrous material in the form of a wick (81 a) or of several parallel wicks by said at least one thermoplastic polymer matrix having the form of a powder, said pre-impregnation step being carried out by dry process in a tank (20) comprising a fluidized bed (22) comprising at least one saturated loading part (82),

2. Method according to claim 1, characterized in that said wick (81a) or said wicks is (are) not sized.

3. Method according to claim 1 or 2, characterized in that the tension of said wick (81a) or said wicks when it (s) enters (s) in the fluidized bed is up to 1000g.

4. Method according to claim 3, characterized in that the tension of said wick (81 a) or said wicks when it (s) penetrates (s) in the fluidized bed is from 100 to 1000 g, in particular from 200 to 1000g, more particularly from 300 to 850g.

5. Method according to one of claims 1 to 4, characterized in that the minimum width of said wick (81a) or said wicks is greater than the width of the groove of said sip.

6. Method according to one of claims 1 to 5, characterized in that said pre-impregnation step is carried out with simultaneous development of said wick (81a) or said wicks between the inlet and the outlet of said fluidized bed (22) .

7. Method according to one of claims 1 to 6, characterized in that the mean diameter D50 by volume of the particles of thermoplastic polymer powder being from 30 to 300 pm, in particular from 50 to 200 pm, more particularly from 70 to 200pm.

8. Method according to one of claims 1 to 7, characterized in that the fiber content in said impregnated fibrous material is between 45 to 65% by volume, preferably from 50 to 60% by volume, in particular from 54 to 60%.

9. Method according to one of claims 1 to 8, characterized in that the residence time in the powder is comprised from 0.01 s to 10 s, preferably from 0.1 s to 5 s, and in particular from 0.1 s to 3s.

10. Method according to one of claims 1 to 9, characterized in that said stuffing piece engorged is a grooved cylindrical roller and the percentage of development of said wick (81a) or said wicks between the inlet and the outlet of said tank being from 1% to 400%, preferably between 30% and 400% preferentially between 30% and 150%, preferably between 50% and 150%.

11. Method according to claim 10, characterized in that a single grooved cylindrical roller is present in the fluidized bed (22) and said prepreg is carried out at the angle CM formed by said wick (81a) or said wicks between the inlet of said grooved cylindrical roller and the vertical tangent to said grooved cylindrical roller.

12. Method according to claim 1 1, characterized in that the angle is comprised from 0 to 89 °, preferably 5 ° to 85 °, preferably from 5 ° to 45 °, preferably from 5 ° to 30 °.

13. Method according to claim 10, characterized in that two cylindrical rollers engorged Ri and R2 are present in said fluidized bed (22) and said prepreg is carried out at the angle formed by said wick (81 a) or said wicks between the inlet of said grooved cylindrical roller Ri and the vertical tangent to said grooved cylindrical roller and / or at the angle 0 (2 formed by said wick (81 a) or said wicks between the inlet of said cylindrical roller grooved R2 and the vertical tangent to said cylindrical grooved roller R2, said grooved cylindrical roller Ri (in the direction of travel of the process) preceding said cylindrical grooved roller R2 and said wick (81 a) or said wicks being able to pass above or below of the R2 roller.

14. Method according to claim 13, characterized in that the two engorged cylindrical rollers Ri and R2 are distant from 0.15 mm to the length equivalent to the maximum dimension of the tank (20), preferably distant from 10mm to 50mm and in that the difference in height between the two cylindrical grooved rollers Ri and R2 is between 0 and the height corresponding to the maximum height of the tank (20) subtracted from the diameters of the two cylindrical grooved rollers, preferably between 0.15 mm at the height corresponding to the maximum height of the tank (20) subtracted from the diameters of the two grooved cylindrical rollers, more preferably at a height difference between 10mm and 300mm, R2 being the upper grooved cylindrical roller.

15. Method according to one of claims 1 to 14, characterized in that a single thermoplastic polymer matrix is used and the thermoplastic polymer powder is fluidizable.

16. Method according to one of claims 1 to 15, characterized in that it further comprises at least one step of heating the matrix thermoplastic allowing the melting or maintaining in fusion of said thermoplastic polymer after pre-impregnation,

17. Method according to one of claims 1 to 16, characterized in that it further comprises a step of shaping said wick or said parallel wicks of said prepreg fibrous material, by calendering by means of at least a heating grille in the form of a single unidirectional ribbon or of a plurality of parallel unidirectional ribbons or plies with, in the latter case, said heating grille comprising a plurality of calendering grooves, preferably up to 300 calendering grooves, in accordance with the number of said ribbons and with a pressure and / or a spacing between the rollers of said calender regulated by a controlled system.

18. The method of claim 17, characterized in that the calendering step is carried out by means of a plurality of heating calenders (51, 52, 53), mounted in parallel and / or in series with respect to the direction of travel. wicks (81a) of fibers.

19. Method according to one of claims 17 or 18, characterized in that said (or said) heating calender (s) (51, 52, 53) comprises (include) a heating system integrated by induction or by microwaves, preferably by microwaves, coupled to the presence of carbonaceous charges in said thermoplastic polymer or mixture of thermoplastic polymers.

20. Method according to one of claims 17 to 19, characterized in that said (or said) heating calender (s) (51, 52, 53) is (are) coupled (s) to a additional rapid heating device (41, 42, 43), located before and / or after said (each) calender (51, 52, 53), in particular a microwave or induction heating device coupled with the presence of carbonaceous charges in said polymer or in said mixture of polymers, or an infrared heater IR, or Laser or by direct contact with another heat source such as a flame or a hot gas.

21. Method according to one of claims 1 to 20, characterized in that said at least one pre-impregnation step (s) is (are) supplemented by a step of covering said single wick (81a) or said plurality of parallel wicks after pre-impregnation with the powder, said covering step being carried out before said calendering step, by a molten thermoplastic polymer, which may be identical or different from said polymer in the form of powder in a fluidized bed (22), said molten polymer preferably being of the same nature as said polymer in the form of a powder in a fluidized bed (22), preferably with said covering being effected by extrusion at a right angle relative to said single wick (81a) or to said plurality of parallel locks.

22. Method according to one of claims 1 to 21, characterized in that said thermoplastic polymer further comprises carbonaceous fillers, in particular carbon black or carbonaceous nanofillers, preferably chosen from carbonaceous nanofillers, in particular graphenes and / or carbon nanotubes and / or carbon nanofibrils or their mixtures.

23. Method according to one of claims 1 to 22, characterized in that said thermoplastic polymer further comprises liquid crystal polymers or cyclized poly (butylene terephthalate), or mixtures containing them as additives.

24. Method according to one of claims 1 to 23, characterized in that said at least thermoplastic polymer is selected from: polyaryl ether ketones (PAEK), in particular poly (ether ether ketone) (PEEK); polyaryl ketone ether ketone (PAEKK), in particular poly (ketone ether ketone) (PEKK); aromatic polyether imides (PEI); polyaryl sulfones, in particular polyphenylene sulfones (PPSU); polyarylsulfides, in particular polyphenylene sulfides (PPS); polyamides (PA), in particular aromatic polyamides optionally modified by urea units; PEBAs, polyacrylates, in particular polymethyl methacrylate (PMMA); polyolefins, in particular polypropylene, polylactic acid (PLA), polyvinyl alcohol (PVA), and fluorinated polymers in particular polyvinylidene fluoride (PVDF) or polytetrafluoroethylene (PTFE) or polychlorotrifluoroethylene (PCTFE); and their mixtures, in particular a mixture of PEKK and PEI, preferably from 90-10% by weight to 60-40% by weight, in particular from 90-10% by weight to 70-30% by weight.

25. The method of claim 24, characterized in that said at least thermoplastic polymer is a polymer whose glass transition temperature is such that Tg> 80 ° C or a semi-crystalline polymer whose melting temperature Tf> 150 ° C .

26. Method according to one of claims 1 to 25, characterized in that said fibrous material comprises continuous fibers selected from carbon, glass, silicon carbide, basalt, silica fibers, natural fibers in particular of flax or hemp, of lignin, of bamboo, of sisal, of silk, or of cellulose in particular of viscose, or of the amorphous thermoplastic fibers of glass transition temperature Tg greater than the Tg of said polymer or of said mixture of polymers when the latter is amorphous or greater than the Tf of said polymer or of said mixture of polymers when the latter is semi-crystalline, or the semi-crystalline thermoplastic fibers with a melting temperature Tf greater than the Tg of said polymer or of said mixture of polymers when the latter is amorphous or higher than the Tf of said polymer or of said mixture of polymers when the latter is semi-crystalline, or a mixture of two or more of said fibers, preferably e a mixture of carbon fibers, glass or silicon carbide, in particular carbon fibers.

27. Unidirectional ribbon of impregnated fibrous material, in particular ribbon wound on a reel, characterized in that it is obtained by a process as defined according to one of claims 16 to 26.

28. Tape according to claim 27, characterized in that it has a width (I) and a thickness (ep) suitable for removal by robot in the manufacture of three-dimensional parts, without the need for slitting, and preferably a a width (I) of at least 5 mm and which can range up to 400mm, preferably between 5 and 50 mm and even more preferably between 5 and 15mm.

29. Tape according to one of claims 27 or 28, characterized in that the thermoplastic polymer is a polyamide chosen from, in particular, an aliphatic polyamide as chosen PA 6, PA 11, PA 12, PA 66, PA 46, PA 610, PA 612, PA 1010, PA 1012, PA 11/1010 or PA 12/1010 or a semi-aromatic polyamide such as PA MXD6 and PA MXD10 or chosen from PA 6 / 6T, PA 66 / 6T, PA 6I / 6T, PA MPMDT / 6T, PA MXDT / 6T, PA PA11 / 10T, PA 11 / 6T / 10T, PA MXDT / 10T, PA MPMDT / 10T, PA BACT / 10T, PA BACT / 6T, PA BACT / 10T / 6T, PA BACT / 6T / 11, PA 11 / BACT / 10T, PA 11 / MPMDT / 10T and PA 11 / MXDT / 10T, PVDF, PEEK, PEKK and an IEP or a mixture thereof.

30. Use of the method as defined according to one of claims 16 to 26, for the manufacture of calibrated tapes suitable for the production of three-dimensional composite parts, by automatic removal of said tapes by means of a robot.

31. Use of the ribbon of impregnated fibrous material, as defined in one of claims 27 to 29, in the manufacture of three-dimensional composite parts.

32. Use according to claim 31, characterized in that said manufacture of said composite parts relates to the fields of transport, in especially automotive, oil and gas, especially offshore, gas storage, civil or military aeronautics, nautical, rail; renewable energies, in particular wind, tidal, energy storage devices, solar panels; thermal protection panels; sports and leisure, health and medical, security and electronics.

33. Three-dimensional composite part, characterized in that it results from the use of at least one unidirectional ribbon of impregnated fibrous material as defined according to one of claims 27 to 29.