WO2018115739A1

WO2018115739A1 - Method for manufacturing a fibrous material pre-impregnated with thermoplastic polymer by spraying

Info

Publication number: WO2018115739A1
Application number: PCT/FR2017/053731
Authority: WO
Inventors: Gilles Hochstetter; Arthur Pierre BABEAU; Thibaut SAVART; François TANGUY; Denis Huze; Mathieu Capelot; Patrice Gaillard
Original assignee: Arkema France
Priority date: 2016-12-22
Filing date: 2017-12-20
Publication date: 2018-06-28
Also published as: JP2020501951A; FR3061067B1; FR3061067A1; KR20190095293A; CN110087847A; EP3558614A1

Abstract

A method for manufacturing a pre-impregnated fibrous material having continuous fibres and a thermoplastic polymer matrix, said pre-impregnated fibrous material being produced in a unidirectional strip or a plurality of parallel unidirectional strips. The method comprises a step of impregnating said fibrous material that is in the form of a strand (81a) or several parallel strands with said thermoplastic polymer in powder form. The impregnation step is carried out by spraying powder by means of one or more nozzle(s) or one or more spray gun(s), by dry means, in a vessel (20), onto said fibrous material, and the amount of the thermoplastic polymer matrix in said fibrous material is controlled by controlling the powder spraying rate.

Description

METHOD FOR MANUFACTURING PRE-IMPREGNATED FIBROUS MATERIAL OF THERMOPLASTIC POLYMER THROUGH PROJECTION

[Field of the invention]

The present invention relates to a method of manufacturing a fibrous material prepreg of thermoplastic polymer.

More particularly, the invention relates to a method of manufacturing a preimpregnated fibrous material comprising an impregnation step for the preparation of a preimpregnated fibrous material, especially at its core, of reduced and controlled porosity, to obtain ribbons of preimpregnated 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 it is shaped, it is in the form of wicks. After shaping, it comes in the form of strips (or tape), or tablecloths. 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 nonwoven.

Such preimpregnated fibrous materials are especially intended for the production of lightweight composite materials for the manufacture of mechanical parts having a three-dimensional structure and having good mechanical and thermal properties. When the fibers are carbon or the resin is loaded with suitable additives, these fibrous materials are able to evacuate electrostatic charges. They therefore have properties compatible with the manufacture of parts in particular in the fields of mechanics, civil or military aeronautics, and nautical, automotive, oil and gas, particularly offshore, storage gas, energy, health and medical, army and armaments, sports and recreation, and electronics.

Such preimpregnated fibrous materials are also referred to as composite materials. They comprise the fibrous material, constituted by the reinforcing fibers, and a matrix constituted by the impregnating polymer. The primary role of this matrix is to maintain the reinforcing fibers in a compact form and to give the desired shape to the final product. This matrix also ensures the charge transfer between the fibers and therefore conditions the mechanical strength of the composite. Such a matrix is also used to protect the reinforcing fibers against abrasion and an aggressive environment, to control the surface appearance and to disperse any fillers between the fibers. The role of this matrix is important for the long-term behavior of the composite material, particularly with regard to fatigue and creep.

[Prior art]

A good quality of the three-dimensional composite parts manufactured from preimpregnated fibrous materials passes in particular through control of the process of impregnating the reinforcing fibers with the thermoplastic polymer.

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

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

Until now, the manufacture of strips of fibrous materials reinforced by impregnation of thermoplastic polymer or thermosetting polymer was carried out according to several processes which depend in particular on the nature of the polymer, the type of final desired composite material and its field of application. applications. Powder impregnation or extrusion technologies at the angle head of molten polymer are often used to impregnate the reinforcing fibers with thermosetting polymers, such as epoxy resins, for example, as described in patent WO2012 / 066241. A2. These technologies are not generally applicable directly to the impregnation with thermoplastic polymers, in particular those with a high glass transition temperature, which have a melt viscosity that is too high to obtain satisfactory impregnation of the fibers and of the semi-finished products. or finishes of good quality.

Another known method of impregnation is the continuous passage of the fibers in an aqueous dispersion of polymer powder or aqueous dispersion of polymer particles or emulsion or aqueous polymer suspension. For example, reference can be made to EP0324680. In this process, a dispersion of powders of micrometric size (approximately 20 μιτι) is used. After soaking in the aqueous solution, the fibers are impregnated with the polymer powder. The process then involves a drying step of passing the fibers through impregnated in a first oven to evaporate the water absorbed during soaking. A heat treatment step of passing the impregnated and dried fibers into a second heating zone at high temperature is then required to melt the polymer to adhere, disperse and coat the fibers.

The main disadvantage of this method is the homogeneity of the deposit which is sometimes imperfect. Another problem with this process is the drying time and the energy consumption which strongly affects the cost of production. In addition the particle size of the powders usually used is fine (typically 20μηη of D50 by volume) and this also increases the final cost of the pre-impregnated ribbon or web.

Moreover, the drying step of this method induces porosity in the pre-impregnated fibers by evaporation of the water.

The preimpregnated fibrous material then needs to be shaped into ribbons for example.

Companies market strips of fibrous materials obtained by a method of impregnating unidirectional fibers by passing the fibers, continuously, in a melt of thermoplastic polymer containing an organic solvent such as benzophenone. For example, US Pat. No. 4,541,884 of Imperial Chemical Industries can be referred to. The presence of the organic solvent makes it possible in particular to adapt the viscosity of the molten mixture and to ensure a good coating of the fibers. The fibers thus pre-impregnated are then shaped. They may for example be cut into strips of different widths and then placed under a press, then heated to a temperature above the melting temperature of the polymer to ensure the cohesion of the material and in particular the adhesion of the polymer to the fibers. This method of impregnation and shaping makes it possible to produce structural parts with high mechanical strength.

One of the drawbacks of this technique lies in the heating temperature required to obtain these materials. The melting temperature of the polymers depends in particular on their chemical nature. It can be relatively high for poly (methyl methacrylate) (PMMA) polymers, or even very high for poly (phenylene sulfide) (PPS), poly (ether ether ketone) (PEEK) or poly ( ether ketone ketone) (PEKK) for example. Temperature Therefore, the heating temperature can rise to temperatures above 250 ° C, and even higher than 350 ° C, temperatures that are much higher than the boiling point and the flash point of the solvent, which are respectively 305 ° C and 150 ° C. C for benzophenone. In this case, there is a sudden departure of the solvent inducing a high porosity within the fibers and therefore causing the appearance of defects in the composite material. The process is therefore difficult to reproduce and involves risks of explosion endangering the operators. Finally, the use of organic solvents is to be avoided for environmental and health and safety reasons.

The document EP 0 406 067, filed in the joint names of Atochem and the French State, as well as the document EPO 201 367 describe a technique for impregnating a fluidized bed of polymer powder. The fibers penetrate into a closed fluidization vessel where, with regard to EP 0 406 067, they are optionally separated from each other by means of rollers or corrugated rolls, the fibers being electrostatically charged by friction in contact with these rollers. or cylinders. This electrostatic charge allows the polymer powder to stick to the surface of the fibers and thus to impregnate them.

The international application WO 2016/062896 describes a wicking of wick by an electrostatic process in voluntary charge, by grounding the wick and application of a potential difference between the tip of a spray gun or powder nozzles and the wick .

The document WO2008 / 135663 describes, in a third variant, the production of an impregnated fiber ribbon. In this document, the fiber ribbon is already preformed prior to the impregnation step, in the form of a ribbon formed of fibers held together by means of contention. The ribbon thus preformed is previously charged with static electricity and immersed in an enclosure containing a fluidized bed of fine polymer particles suspended in the compressed air, so as to coat the ribbon with a layer of polymer coating. Such a document does not make it possible to impregnate one or more fiber strands simultaneously or a shaping, continuously, the pre-impregnated rovings in the form of ribbons.

EP2586585 also describes the principle of impregnating fibers by passing them into a fluidized bed of polymer particles. On the other hand, he does not describe continuous shaping of one or more wicks thus impregnated, in the form of one or more unidirectional parallel ribbons.

The application US 2002/0197397 describes a process for impregnating fibers with a mixture of polymer powders, said mixing being carried out without prior compounding directly in a fluidized bed.

The international application WO 2015/121583 describes a method of manufacturing a fibrous material pre-impregnated by impregnation of said material in a fluidized bed and hot calendering of said wick.

The hot calendering is carried out downstream of the impregnation device and makes it possible to homogenize the distribution of the polymer and the impregnation of the fibers. The porosity obtained is controlled and reproducible but not quantified.

The document EP0335186 describes the possibility of using a calender or a press for compacting a composite comprising preimpregnated metal fibers, used for the manufacture of molded bodies for the shielding against electromagnetic radiation. It does not disclose impregnating one or more fiber strands and continuously shaping them into one or more unidirectional parallel strips by hot calendering.

Regarding the shaping of preimpregnated fibrous materials in the form of calibrated tapes, suitable for the manufacture of three-dimensional composite parts by automatic removal by means of a robot, this is generally carried out in post-processing.

Thus, the document WO92 / 20521 describes the possibility of impregnating a wick of fibers by passing it in a fluidized bed of particles of thermoplastic powder. The fibers thus coated with polymer particles are heated in an oven or heater so that the polymer penetrates well and covers the fibers. A post-treatment of the obtained prepreg fibrous reinforcement can be to pass it through a polishing roll assembly to improve the impregnation with the still liquid matrix. One or more superposed fibrous reinforcements may further be placed between two rollers so as to form a band. Such a document does not make it possible to impregnate one or more strands of fibers and shaping, continuously, preimpregnated strands in the form of one or more unidirectional parallel strips.

The quality of the pre-impregnated fibrous material tapes, and therefore the quality of the final composite material, depends not only on the homogeneity of the impregnation of the fibers and therefore the control and reproducibility of the porosity of the preimpregnated fibrous material, but also the size and more particularly the width and thickness of the final ribbons. Regularity and control of these two dimensional parameters make it possible to improve the mechanical strength of the materials.

At present, whatever the process used for the impregnation of fibrous materials, the manufacture of ribbons of small width, that is to say of width less than 400 mm, generally requires a slitting (that is to say a cutting) of widths greater than 400 mm, also called tablecloths. The ribbons thus dimensioned are then taken back to be deposited by a robot using a head. In addition, rolls of webs not exceeding a length of the order of 1 km, ribbons obtained after cutting are generally not long enough to manufacture some large composite parts during removal by robot. The ribbons must therefore be roped to obtain a longer length, creating extra thicknesses. These extra thicknesses lead to the appearance of heterogeneities that are detrimental to obtaining good quality composite materials constituting said composite parts.

In addition, these extra thicknesses require a machine stop and the restart of the robot and thus loss of time and productivity.

Current techniques for impregnating fibrous materials and shaping such fibrous materials pre-impregnated in the form of calibrated ribbons therefore have several disadvantages. For example, it is difficult to homogeneously heat a molten mixture of thermoplastic polymers in a die and at the die outlet to the core of the material, which alters the quality of the impregnation. In addition, the difference in temperature existing between the fibers and a molten mixture of polymers at the level of the impregnation die also alters the quality and homogeneity of the impregnation. In addition, this mode of impregnation melt does not allow to obtain high fiber levels or high production speeds because of the high viscosity of thermoplastic resins, especially when they have high glass transition temperatures, which is necessary to obtain high performance composite materials. The use of organic solvents usually involves the appearance of defects in the material as well as environmental, health and safety risks in general. The shaping, by post-treatment at high temperature of the material fibrous pre-impregnated in the form of strips, remains difficult because it does not always allow a homogeneous distribution of the polymer within the fibers which leads to obtaining a lower quality material, with poorly controlled porosity. The slitting of plies for obtaining calibrated ribbons and the splicing of these ribbons induces an additional cost of manufacture. The slitting also generates significant dust problems that pollute the ribbons of pre-impregnated fibrous materials used for robot removal and can cause malfunctions of the robots and / or imperfections on the composites. This potentially leads to robot repair costs, a shutdown of production and the scrapping of non-compliant products. Finally, during the slitting step, a not insignificant amount of fibers is deteriorated, inducing a loss of properties, and in particular a reduction of the mechanical strength and conductivity, ribbons of preimpregnated fibrous material.

Furthermore, the impregnation does not always take place at heart and if said documents cited above indicate a thorough impregnation, it turns out that the porosity obtained is too important, especially for the applications listed above.

[Technical problem]

The invention therefore aims to remedy at least one of the disadvantages of the prior art. The invention aims in particular to provide a method for manufacturing a preimpregnated fibrous material, by an impregnation technique associating a control of the projection rate of the powder in the impregnating device and a control of the development of said fibrous material at said device, and to obtain a preimpregnated fibrous material having a homogeneous impregnation of the fibers, particularly at the core, and controlled dimensions, with a reduced, controlled and reproducible porosity on which the performance of the final composite part depend . [Brief description of the invention]

For this purpose, the subject of the invention is a process for manufacturing a preimpregnated fibrous material comprising a fibrous material made of continuous fibers and at least one thermoplastic polymer matrix, comprising a step of impregnation, particularly at the core, of said material. fibrous in the form of a wick or several parallel locks with at least one thermoplastic polymer matrix in the form of a powder.

The invention also relates to a unidirectional ribbon of preimpregnated fibrous material, in particular ribbon wound on a reel, characterized in that it is obtained by a method as defined above.

The invention further relates to a use of the tape as defined above in the manufacture of three-dimensional parts. Said manufacture of said composite parts concerns the fields of transport, in particular automobile, oil and gas, in particular offshore, gas storage, civil or military aeronautics, nautical, railway; renewable energy, in particular wind turbine, tidal turbine, energy storage devices, solar panels; thermal protection panels; sports and recreation, health and medical, ballistics with weapon or missile parts, 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 tape of preimpregnated fibrous material as defined above.

[Detailed description of the invention]

The subject of the invention is a process for manufacturing a preimpregnated fibrous material comprising a fibrous material made of continuous fibers and at least one thermoplastic polymer matrix, characterized in that said preimpregnated fibrous material is produced in a single unidirectional ribbon or in a plurality unidirectional parallel ribbons and in that said method comprises a step of impregnation, in particular at heart and homogeneous, said fibrous material being in the form of a wick or several parallel wicks by said at least one thermoplastic polymer matrix presenting in the form of a powder, said impregnation step being carried out by spraying said powder with a nozzle (or nozzles) or a gun (s) by dry route in a tank on said fibrous material and the control the rate of said at least one thermoplastic polymer matrix in said fibrous material being made by controlling the d projection bit of said powder by said one or more nozzle (s) or said (or said) gun (s) of said fibrous material, excluding any electrostatic process voluntary load. The inventors have unexpectedly found that the control of the projection rate of said nozzle (or of said nozzles) or of said gun (or said guns) on said fibrous material made it possible to impregnate the fibrous material with the thermoplastic polymer matrix, in particular at heart and homogeneous with a well controlled rate of resin.

The term "homogeneous" means that the impregnation is uniform and that there is no decrease in the width of the ribbons or dry fibers at the surface of the preimpregnated fibrous material.

Polymer matrix

Thermoplastic, or thermoplastic polymer, is understood to mean a material that is generally solid at ambient temperature, that can be semi-crystalline or amorphous, and that softens during an increase in temperature, in particular after passing its glass transition temperature (Tg). and flows at a higher temperature when it is amorphous, or can present a blunt fusion at the passage of its so-called melting temperature (Tf) when it is semi-crystalline, and which becomes solid again during a decrease in temperature below its crystallization temperature (for a semi-crystalline) and below its glass transition temperature (for an amorphous).

Tg and Tf are determined by Differential Scanning Calorimetry (DSC) according to standard 1 1357-2: 2013 and 1 1357-3: 2013 respectively.

As regards the polymer constituting the impregnating 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 crushed in powder form so that it can be used in a device such as a tank.

The device in the form of a tank can be open or closed.

Optionally, the thermoplastic polymer or thermoplastic polymer blend further comprises carbonaceous fillers, in particular carbon black or carbon nanofillers, preferably chosen from carbon nanofillers, in particular graphenes and / or carbon nanotubes, and or carbon nanofibrils or mixtures thereof. These charges make it possible to conduct electricity and heat, and consequently make it possible to improve the lubrication of the polymer matrix when it is heated. Optionally, said thermoplastic polymer comprises at least one additive, especially chosen from a catalyst, an antioxidant, a thermal stabilizer, a UV stabilizer, a light stabilizer, a lubricant, a filler, a plasticizer, a flame retardant, a nucleating agent , a chain extender and a dye or a mixture thereof.

According to another variant, the thermoplastic polymer or thermoplastic polymer blend may further comprise liquid crystal polymers or cyclized poly (butylene terephthalate), or mixtures containing them, such as the CBT100 resin marketed by 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 make the impregnation matrix, in particular its melting temperature, one or other of these compounds will be chosen.

The thermoplastic polymers forming part of the impregnation 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 (PPAs)),

polyureas, in particular aromatic,

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

polymers and copolymers of the polyaryletherketone (PAEK) family, such as polyetheretherketone (PEEK), or polyaryletherketone ketones (PAEKK) such as polyetherketone ketone (PEKK) or their derivatives,

aromatic polyether-imides (PEI),

polyarylsulfides, in particular polyphenylene sulfides (PPS),

polyarylsulphones, in particular polyphenylene sulphones (PPSU),

polyolefins, in particular polypropylene (PP);

polylactic acid (PLA),

polyvinyl alcohol (PVA), fluorinated polymers, in particular polyvinylidene fluoride (PVDF), or polytetrafluoroethylene (PTFE) or polychlorotrifluoroethylene (PCTFE),

and their mixtures.

Advantageously, when said thermoplastic polymer is in a mixture, it is added to the tank in powder form previously obtained by "dry blend" or compound or directly into the tank in the form of "dry blend". Advantageously, it is added in powder form previously obtained by "dry blend" or directly into the tank in the form of "dry blend" 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 from 1 -99% to 99-1%. Advantageously, the PEKK / PEI mixture is from 90-10% to 60-40% by weight, in particular from 90-10% to 70-30% by weight.

The thermoplastic polymer may be the non-reactive final polymer that will impregnate the fibrous material or a reactive prepolymer, which will also impregnate the fibrous material, but is capable of reacting on itself or with another prepolymer, depending on the chain ends being carried. by said prepolymer, after impregnation, or with a chain extender and in particular during heating at a heating calender.

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

According to a third possibility, said prepolymer may comprise or consist of at least one prepolymer of said thermoplastic polyamide polymer, carrier of n terminal reactive functions X, chosen from: -NH2, -CO2H and -OH, preferably NH2 and -CO2H with n being 1 to 3, preferably 1 to 2, more preferably 1 or 2, more particularly 2 and at least one Y-A'-Y chain extender, with A 'being a hydrocarbon biradical, of non-polymeric structure, bearing 2 identical Y terminal reactive functions, reactive by polyaddition with at least one X function of said prepolymer a1), preferably of molecular weight 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 may correspond to inherent viscosities greater than or equal to 0.8 such determined in m-cresol according to ISO 307: 2007 but changing the solvent (use of m-cresol in place 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 1,000 to 6,000, in particular from 2,500 to 6,000.

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

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

The polyamide may be a homopolyamide or a copolyamide or a mixture thereof.

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) which may be modified by urea units, and copolymers thereof, polymethyl methacrylate (PPMA) and copolymers thereof, polyetherimides (PEI), polyphenylene sulfide (PPS), polyphenylene sulfone (PPSU), polyetherketoneketone (PEKK), the Polyetheretherketone (PEEK), fluorinated polymers such as polyvinylidene fluoride (PVDF).

For the fluoropolymers, 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 weight of VDF and at least one other monomer copolymerizable with VDF. The VDF content must be greater than 80% by weight, or even better 90% by weight, to ensure good mechanical strength to the structural part, especially when it is subjected to thermal and chemical stresses. The comonomer may be a fluorinated monomer such as, for example, vinyl fluoride.

For structural parts that must withstand high temperatures, in addition to the fluorinated polymers, PAEK (PolyArylEtherKetone) such as PEK polyether ketones, PEEK poly (ether ether ketone) and polyetherketone are advantageously used according to the invention. ketone) PEKK, Poly (ether ketone ether ketone ketone) PEKEKK or PA high temperature glass transition Tg). Advantageously, said thermoplastic polymer is a polymer whose glass transition temperature is such that Tg> 80 ° C or a semicrystalline 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 1 2 (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 these,

a semi-aromatic polyamide, optionally modified with 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 having the formula (diamine Ca). (diacid in Cb), with a representing the number of carbon atoms of the diamine and b representing the number of carbon atoms of the diacid, a and b being each between 4 and 36, advantageously between 9 and 18, the a (Ca-diamine) unit being chosen from linear or branched aliphatic diamines, cycloaliphatic diamines and alkylaromatic diamines and the (Cb diacid) unit being selected from linear or branched aliphatic diacids, cycloaliphatic diacids and aromatic diacids;

XT denotes a unit obtained from the polycondensation of a diamine in Cx and terephthalic acid, with x representing the number of carbon atoms of the diamine in Cx, 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, 66 / 6T, 6I / 6T, MPMDT / 6T, PA1 1 / 10T, 1 1 / 6T / 10T, MXDT / 10T or MPMDT / 10T, BACT / 10T, MXD6 and MXD10 and block copolymers, especially polyamide / polyether (PEBA).

T is terephthalic acid, MXD is m-xylylene diamine, MPMD is methylpentamethylene diamine, and BAC is bis (aminomethyl) cyclohexane.

Fibrous material:

As regards the fibers of constitution of said fibrous material, they are in particular fibers of mineral, organic or vegetable origin. 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 thermoplastic or thermosetting polymer-based fibers, 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 thermoplastic polymer mixture of constitution of the impregnation matrix when the latter is amorphous, or greater than the Tf of the polymer or mixture of thermoplastic polymer constitution of the impregnation matrix when the latter is semi-crystalline. Advantageously, they are based on semicrystalline thermoplastic polymer and have a melting temperature Tf greater than the Tg of the polymer or thermoplastic polymer mixture of constitution of the impregnation matrix when the latter is amorphous, or greater than the Tf of the polymer or mixture of thermoplastic polymer constitution of the impregnation matrix when the latter is semi-crystalline. Thus, there is no risk of fusion for the organic fibers constituting the fibrous material during impregnation with the thermoplastic matrix of the final composite. Among the fibers of plant origin, mention may be made of natural fibers based on flax, hemp, lignin, bamboo, silk including spider, sisal, and other cellulosic fibers, especially viscose. These plant-based fibers can be used pure, treated or coated with a coating layer, in order to facilitate the adhesion and impregnation of the thermoplastic polymer matrix. The fibrous material may also be a fabric, braided or woven with fibers. It can also correspond to fibers with holding wires.

These constituent fibers can be used alone or in mixtures. Thus, organic fibers may be mixed with the mineral fibers to be impregnated with thermoplastic polymer and form the preimpregnated fibrous material.

The locks of organic fibers may have several grammages. They can also have several geometries. The fibers may be in the form of short fibers, which then compose 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 may also be in the form of a mixture of these reinforcing fibers of different geometries. Preferably, the fibers are continuous.

Preferably the fibrous material is constituted by continuous fibers of carbon, glass or silicon carbide or their mixture, in particular carbon fibers. It is used in the form of a lock or several locks.

In pre-impregnated materials also known as "ready-to-use", the polymer or mixture of thermoplastic impregnating polymers is distributed uniformly and homogeneously around the fibers. In this type of material, the thermoplastic impregnating polymer must be distributed as homogeneously as possible within the fibers in order to obtain a minimum of porosities, ie a minimum of voids between the fibers. Indeed, the presence of porosities in this type of material can act as points of concentration of stress, during a mechanical tensile stress for example, and which then form fracture initiation points of the pre fibrous material. -impregnated and weakened mechanically. A homogeneous distribution of the polymer or polymer mixture thus improves the mechanical strength and the homogeneity of the composite material formed from these preimpregnated fibrous materials. Thus, in the case of "ready-to-use" prepreg materials, the level of fibers in said impregnated fibrous material is 45 to 65% by volume, preferably 50 to 60% by volume, especially 54 to 60% by volume.

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

Advantageously, the porosity rate of said preimpregnated fibrous material is between 0% and 30%, especially from 1% to 10%, in particular from 1% to 5%.

The porosity rate corresponds to the closed porosity rate and can be determined either by electron microscopy or as being the relative difference between the theoretical density and the experimental density of said preimpregnated fibrous material as described in the examples of this section. invention.

Impregnation stage:

An exemplary implementation unit of the manufacturing method is described in the international application WO 2015/121583 and is shown in FIG. 1, with the exception of the tank (otherwise called impregnation tank which in the case of the The invention comprises a vessel provided with a docking piece which may be a compression roll (FIG. 4) and nozzle (s) or spray gun (s) (FIG. 3).

The step of impregnating the fibrous material is carried out by passing one or more wicks in a continuous impregnation device by projection, comprising a tank (20), comprising one or more nozzles (s) or a gun or pistols. (s) projecting the polymer powder onto the fibrous material at the roll inlet.

The polymer (s) or polymer powder is projected into the tank by means of nozzle (s) or gun (s) at the part of the binder including the compression roller (input) on said fibrous material. The wick or wicks are circulated in this tank. The tank may have any shape, in particular cylindrical or parallelepipedal, in particular a rectangular parallelepiped or a cube, advantageously a rectangular parallelepiped.

The tank may 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 can not leave said tank.

This impregnation step is therefore carried out dry, that is to say that the thermoplastic polymer matrix is in powder form, and projected into the air, but can not be dispersed in a solvent or in water .

Each wick to be impregnated is unrolled from a device (10 to reels (1 1) under the traction generated by cylinders (not shown) .The device 10 preferably comprises a plurality of reels (1 1), each reel allowing For example, it is possible to impregnate a plurality of fiber strands simultaneously.Each wire feeder (1 1) is provided with a brake (not shown) so as to apply tension to each strand of fibers. In this case, an alignment module (12) makes it possible to arrange the fiber strands parallel to each other, in this way the strands of fibers can not be in contact with one another, which makes it possible to avoid mechanical degradation of the fibers by friction between them.

The fiber wick or the parallel fiber locks then pass into a tank (20), provided with a part that is a compression roll (23) in the case of Figure 1.

The compression roller can be fixed or rotatable.

The fiber wick or the parallel fiber locks then spring out of the tank after impregnation after controlling the rate of projection of said powder by said nozzle (or said nozzles) or said gun (or said) on said fibrous material.

The inventors have therefore unexpectedly found that the control of the rate of projection of said powder by said nozzle (or said nozzles) or said gun (or said guns) on said fibrous material allowed to impregnate the fibrous material by the thermoplastic polymer matrix. , with a resin level well controlled and homogeneously. They also found that through the use of at least one impregnation impregnation was improved compared to the methods of the prior art, in particular, the impregnation is at heart.

By docking part is meant any system on which the wick has the ability to scroll in the tank. The docking piece can have any shape from the moment the wick can scroll on.

An example of a docking piece, without restricting the invention to it, is detailed in FIG.

This impregnation is performed to allow the polymer powder to penetrate the core of the fiber wick and adhere to the fibers sufficiently to support the transport of the powdered wick from the tub. The wick or pre-impregnated with the powder, is (are) directed (s) then to a heating calendering device, with possibility of preheating before calendering and optional heating post-calendering.

Optionally, this impregnation step can be completed by a step of covering the wick or pre-impregnated wicks, just at the outlet of the powder impregnation vat (20), and just before formatting step by calendering. For this purpose, the outlet lock of the tank (20) can be connected to a covering device (30) which can comprise a cover angle head, as is also described in the patent EP0406067. The overlay polymer may be the same or different from the in-tank polymer powder. Preferably, it is of the same nature. Such a covering not only makes it possible to complete the fiber impregnation step in order to obtain a final polymer volume content in the desired range and to avoid the presence on the surface of the pre-impregnated wick, of a level of fibers that is locally too high. important, which would interfere with the welding of the steps during the manufacture of the composite part, in particular for obtaining fibrous materials known as "ready to use" good quality, but also to improve the performance of the composite material obtained.

The process of the invention as indicated above is carried out by the dry method, excluding an electrostatic process in voluntary charge.

The expression "in voluntary charge" means that a potential difference is applied between the fibrous material and the powder. The charge is notably controlled and amplified. The powder grains then impregnate the fibrous material by attraction of the loaded powder opposite the fiber. The powder can be electrically charged, negatively or positively, by different 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 unit of implementation before or at the level of the tank but which are in any case involuntary loads.

Advantageously, the tank comprises at least one docking piece, said wick or said wicks being in contact with a part or the whole of the surface of said at least one piece of docking.

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

Below 45% of fibers, the reinforcement has no interest as regards the mechanical properties.

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

If the fibrous material, such as fiberglass, has a sizing, an optional de-sizing step can be performed before the fibrous material passes into the tank. The term "sizing" refers to the surface treatments applied to the reinforcing fibers at the end of the die (textile sizing) and on the fabrics (plastic sizing).

The "textile" size applied to the filaments at the outlet of the die consists of depositing a bonding agent ensuring the cohesion of the filaments between them, reducing abrasion and facilitating subsequent handling (weaving, draping, knitting) and avoiding formation. electrostatic charges.

The "plastic" or "finish" size applied to the fabrics consists in depositing a bridging agent whose roles are to ensure a physico-chemical bond between the fibers and the resin and to protect the fiber from its environment.

Advantageously, the level of fibers in said impregnated fibrous material is from 50 to 60%, in particular from 54 to 60% by volume. Advantageously, the projection rate of the powder by the (or) nozzle (s) or the (or) gun (s) is from 10g / min to 400g / min, in particular from 20 to 150 g / min.

This flow rate is for each gun or nozzle and may be the same or different for each gun or nozzle.

The rate of projection of the powder onto fibrous material is essential for the impregnation, especially at the core, of said fibrous material.

Below 10g / min, the air flow is not sufficient to convey the powder.

Above 400g / min, the diet is turbulent.

Advantageously, said impregnation step is performed with simultaneous expansion of said wick or said wicks between the inlet and the outlet of said vessel.

The expression "inlet of said tank" corresponds to the vertical tangent of the edge of the tank which comprises the roller or rollers with nozzle (s) or gun (s).

The expression "outlet of said tank" corresponds to the vertical tangent of the other edge of the tank which comprises the roller or rollers with nozzle (s) or gun (s).

Depending on the geometry of the tank, the distance between the inlet and the outlet of the tank 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 development consists in singling out as much as possible each constituent filament of said wick from the other filaments which surround it in its nearest space. It corresponds to the transverse spreading of the wick.

In other words, the transverse spreading or the width of the wick increases between the inlet of the tank and the outlet of the tank and thus allows improved impregnation, especially at the core of the fibrous material.

The tank can be open or closed, in particular it is open.

Figure 3 details a tank (20) comprising a height-adjustable bartacking piece (82).

The wick (81 a) corresponds to the wick before impregnation which is in contact with a part or the totality of the surface of the said at least one piece of docking and thus runs partially or totally on the surface of the piece of baiting ( 82) said system (82) being immersed in the tank where the impregnation takes place. Said bit then emerges from the tank (81b) after controlling the projection rate of the powder at the roll inlet.

Said bit (81 a) may or may not be in contact with the edge of the bowl (83a) which may be a rotating or fixed roll or a parallelepipedal edge.

Advantageously, said wick (81 a) 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 bit (81b) may or may not be in contact with the edge of the bowl (83b) which may be a roller, in particular a cylindrical and rotary or fixed roll, or a parallelepipedal 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 rotating 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 rotating.

Advantageously, said mating piece is perpendicular to the direction of said wick or said locks.

Advantageously, said development of said wick or said wicks is performed at least at said at least one part of the baiting.

The blooming of the wick is therefore mainly at the level of the mating part but can also be performed 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 mating piece is a convex, concave or cylindrical compression roll.

The convex form is favorable to the development whereas the concave form is unfavorable to the blooming although it is nevertheless carried out.

The expression "compression roll" means that the wicking bit rests partially or completely on the surface of said compression roller, which induces the development of said wick. Advantageously, said at least one compression roller is of cylindrical shape and the percentage of expansion of said wick or said wicks between the inlet and the outlet of said vessel is from 1% to 400%, preferably between 30% and 400%. preferably between 30% and 150%, preferably between 50% and 150%.

The development is a function of the fibrous material used. For example, the blooming of a carbon fiber material is much greater than that of a flax fiber.

The development is also a function of the number of fibers or filaments in the wick, their average diameter and their cohesion by the size.

The diameter of said at least one compression 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 compression roll is too great.

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

When the mating part is at least one compression roller, according to a first variant, a single compression roller is present in the vessel and said impregnation is performed at the angle α formed by said wick or said wicks between input of said compression roller and the vertical tangent to said compression roller.

The angle α formed by said wick or said wicks between the inlet of said compression roller and the vertical tangent to said compression 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 compression roller allows impregnation over a larger width of wick and thus improved impregnation compared to techniques of the improved prior art. The coupling with the controlled projection flow then allows a thorough impregnation.

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

However, an angle α of 0 to 5 ° is likely to cause risks of mechanical stress, which will lead to breakage of fibers and an angle of 85 ° to 89 ° does not create enough mechanical force to create the "wedge effect".

A value of the angle ai equal to 0 ° therefore corresponds to a vertical fiber. It is obvious that the height of the cylindrical compression roller is adjustable thus allowing to position the fiber vertically.

It would not be outside the scope of the invention if the wall of the tank was pierced so as to allow the exit of the wick.

Advantageously, the edge of the tank (83a) is equipped with a roller, in particular a cylindrical and rotary roller on which said wick or said wicks runs, thus leading to a prior development.

Advantageously, one or more difficulties are present downstream of the tank at which the blooming is initiated.

Advantageously, the blooming is initiated at the said one or more of the aforementioned obstacles and continues at the edge of the tank (83a).

The development is then maximum after passage at the compression roll or rolls.

FIG. 4 describes an embodiment, but not limited thereto, to a single compression roll, with a vessel (20) including a powder spray gun (84) and in which a single roll of cylindrical compression is present and showing the angle CM.

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

Advantageously, the level of said powder in said tank is at least located at the mid-height of said compression roller.

It is obvious that the "corner effect" caused by the angle CM favors the impregnation on one face but the development of said wick obtained thanks to the compression roller also allows to have an impregnation on the other side of said wick. In other words, said impregnation is favored on one side of said wick or said wicks at the angle CM formed by said wick or said wicks between the inlet of said at least one compression roller Ri and the vertical tangent to the compression roller Ri but the blossoming also allows to impregnate the other face.

The angle CM is as defined above.

According to a second variant, when the mating part is at least one compression roll, then two compression rolls R 1 and R 2 are in said tub and said impregnation is performed at the angle α 1 formed by said wick or said wicks between the inlet of said compression roller Ri and the vertical tangent to said compression roller Ri and / or at the angle C ( 2 formed by said wick or said wicks between the inlet of said compression roller R2 and the vertical tangent to said compression roller R2, said compression roller Ri preceding said compression roller R2 and said wick or said wick being able to pass above ( Figure 5 and 6) or below (Figure 7 and 8) of the roller R2.

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

Advantageously, the two compression rollers are identical and cylindrical non-corrugated and in particular metal.

The diameter of the two compression rollers may also be the same or different and is as defined above.

Advantageously, the diameter of the two compression rollers is identical. The two compression rollers R 1 and R 2 may be at the same level with respect to each other and relative to the bottom of the vessel (FIGS. 6 and 7) or offset relative to one another and relative to each other. at the bottom of the tank, the height of the compression roller Ri being greater or smaller than that of the compression 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 from 0 to 90 °.

Advantageously, said impregnation is therefore performed at the angle α formed by said wick or said wicks between the inlet of said compression roller Ri and the vertical tangent to said compression roller on one face of said wick and at the level of the angle 02 formed by said wick or said wicks between the inlet of said compression roller R2 and the vertical tangent to said compression roller R2 on the opposite side of said wick which is obtained by passing over the roller R2.

Advantageously, said lock in this embodiment is subject to expansion at each angle α1 and θ2.

FIG. 6 depicts an embodiment, without being limited thereto, to two compression rolls R 1 and R 2, R 1 preceding R 2, with a vessel (20) including a powder spray gun (84) in which two rolls of cylindrical compression, at the same level and side by side, are present and showing the case where said one or more wicks emerge between said compression rolls R 1 and R 2.

In this case, the angle θ2 is equal to 0 and said one or more bits pass over the roller R2.

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

Alternatively, said wick or said strands pass (nt) between said said compression rollers R 1 and R 2 and spring (ent) after being in contact with a part or the whole of the surface of said compression roller R2.

Advantageously, said wick or said wicks is (are) in input contact with a part or the totality of the surface of said compression roller Ri and spring (ent) outside the compression roller R2 after being in contact with a part or all of the surface of said compression roller R2, under the roller R2, the angle O 2 being formed by said wick or said wicks between the inlet of said compression roller R2 and the vertical tangent to said compression roller R2. In this case, the angle C (2 = 90 ^o .

Said impregnation is therefore performed at the angle α formed by said wick or said wicks between the inlet of said compression roller Ri and the vertical tangent to said compression roller on one side of said wick and at the angle 02 formed by said wick or said wicks between the inlet of said compression roller R2 and the vertical tangent to said compression roller R2 on the same face of said wick, but the blooming also impregnates the other face.

Figure 7 shows an exemplary embodiment with two compression rollers R1 and R2 at the same level relative to each other.

According to another embodiment of the second variant, when two compression rollers are present then the distance between the two compression rollers R 1 and R 2 is 0.15 mm to the length equivalent to the maximum dimension of the vessel, preferably ranging from 10mm to 50mm and the difference in height between the two compression rollers R 1 and R 2 is from 0 to the height corresponding to the maximum height of the vessel subtracted from the diameters of the two compression rollers, preferably 0.15 mm at the height corresponding to the maximum height of the vessel subtracted from the diameters of the two compression rollers, more preferably to a difference in height of between 10 mm and 300 mm, R2 being the upper compression roll.

FIG. 8 describes an embodiment, without being limited thereto, to two compression rolls R 1 and R 2, R 1 preceding R 2, with a vessel (20) each comprising a powder projection gun (84) (85) and in which two cylindrical compression rollers at different levels are present and showing the angle The projection rate of said powder by each gun on said fibrous material is the same or different, in particular the same.

The diameter of the compression rollers R 1 and R 2 is shown as identical in FIGS. 5, 6, 7 and 8, but the diameter of each cylindrical compression roll may be different, the diameter of the compression roll R 1 may be greater or smaller than that of the compression roller R2 in the range as defined above.

Advantageously, the diameter of the two compression rollers is identical. It would not depart from the scope of the invention if the compression roller Ri was greater than the compression roller R2.

According to a third variant, when two compression rollers are present and at different levels, then at least a third compression roll R3 is additionally present and situated between the compression rollers R 1 and R 2 in the height direction (FIG. 9 ). Each compression roll comprises a powder spray gun (84) and the rate of projection of said powder by each gun onto said fibrous material at the roll inlet is the same or different, especially the same.

Advantageously said wick or said wicks is (are) in input contact with a part or the totality of the surface of said compression roller Ri and then with a part or the totality of the surface of said compression roller R3 and spring (ent) after having has been in contact with a part or the whole of the surface of said compression roller R2.

Advantageously, said impregnation is performed on one face of said wick or said wicks at the angle α formed by said wick or said wicks between the inlet of said at least one compression roller Ri and the tangent vertical to the compression roller Ri and at the angle C (3 formed by said wick or said wicks and the vertical tangent to the compression roller R3 and on the other side at the angle formed 02 by said wick or said wicks and the vertical tangent to the compression roller R2.

Advantageously, when two compression rollers are present at different levels and at least one third compression roller R3 is additionally present, then the angle O 2 formed by said wick or said wicks between the inlet of said at least one roller 2 and the vertical tangent to said compression roller R2 is between 180 ° and 45 °, in particular between 120 ° and 60 °. Advantageously, the angle θ is from 0 ° to 180 °, advantageously from 45 ° to 135 °.

FIG. 9 describes an embodiment, without being limited thereto, with a tank (20) comprising two compression rolls R 1 and R 2, R 1 preceding R 2, and a third compression roll R 3 and showing the angles C M, O 2 and 03.

The diameter of the compression rollers R 1, R 2 and R 3 is shown as the same in FIG. 9 but the diameter of each cylindrical compression roll may be different, or two compression rolls may have the same diameter and the third a different diameter greater than lower, in the range as defined above.

Advantageously, the diameter of the three compression rollers is identical. Advantageously, in this third variant, a second control of the development of said wick or said wicks is performed at the compression roller R3 and a third control of the development is performed at the compression roller R3.

The projection rate in this third variant is as defined above.

It would not be departing from the scope of the invention if in this third variant, said wick or said wicks is (are) in contact with some or all of the surface of said compression roller Ri and then with some or all of of the surface of said compression roller R2 and spring (ent) after being in contact with a part or the whole of the surface of said compression roller R ₃ .

Advantageously, the spraying rate in the tank is from 10 g / min to 400 g / min, in particular from 20 to 150 g / min. Advantageously, the volume diameter D90 of the particles is 50 to 500 μιτι, preferably 120 to 300 μιτι.

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

Advantageously, the volume diameter of the powder particles is included in the D90 / D10 ratio, ie between 1.5 and 50, advantageously between 2 and 10.

Advantageously, the average volume diameter of the thermoplastic polymer powder particles is between 30 and 300 μιτι, in particular from 50 to 200 μιτι, more particularly from 70 to 200μηη.

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

The "D50" corresponds to the average diameter by volume, ie the value of the particle size which divides the particle population examined in exactly two parts.

The "D90" corresponds to the value at 90% of the cumulative curve of the particle size distribution in volume.

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

Optionally, in the method according to the invention, one or more difficulties are present after the tank.

Step of formatting

As soon as it (their) outlet from the tank (20), the wick (parallel locks) prepreg, possibly covered (s) with a molten polymer, is (are) shaped in the form of a single ribbon unidirectional or a plurality of parallel unidirectional ribbons, by means of a continuous calendering device comprising one or more heating calandres.

Advantageously, the heating calenders of the calendering device are coupled to rapid heating means which make it possible to heat the material not only at the surface but also at the core.

The wick blooming at the outlet of the tank (20) then shrinks under the effect of heating, which contributes to inserting the molten polymer between the fibers of the wick. thus making it possible to reduce the porosity of said wick and promoting impregnation, especially at the core of said wick.

The mechanical stress of the calenders coupled to these rapid heating means makes it possible to eliminate the presence of porosities and to homogeneously distribute the polymer, especially when the fibrous material is a so-called "ready-to-use" material.

Advantageously, this hot calendering not only allows the impregnating polymer to be heated so that it penetrates, adheres and uniformly covers the fibers, but also to control the thickness and the width of the pre-fibrous material tape (s). -imprégné.

In order to be able to produce a plurality of unidirectional parallel ribbons, that is to say as many ribbons as parallel strands pre-impregnated, passed into the tank, the heating calenders, referenced (51), (52), (53) on the diagram of Figure 1, advantageously comprise a plurality of grooves (73) calendering, in accordance with the number of ribbons. This number of grooves may, for example, be up to 200. A SYST slave system also makes it possible to regulate the pressure and / or the spacing E between the rollers (71), (75) of the shell (70), in such a way that to control the thickness ep of the ribbons. Such a shell (70) is shown schematically in Figure 2 described below.

The calendering device comprises at least one heating radiator (51). Preferably, it comprises several heating calandres (51), (52), (53) connected in parallel and / or in series with respect to the direction of travel of the fiber strands. In particular, characterized in that the successive calendering step is carried out in a progressive manner with pressures between the rollers which are increasing (in the running direction of the process) and / or a spacing between the rollers which decreases (in the running direction of the process).

The fact of having several calenders in series makes it possible to compact the material and to reduce the rate of porosities in the material and to reduce their rate. This plurality of calenders is therefore important when it is desired to produce so-called "ready-to-use" fibrous materials.

Having several calenders in parallel increases the number of pre-impregnated wicks.

Advantageously, each calender of the calendering device has an integrated heating system by induction or microwave, preferably by microwaves, for heating the polymer or mixture of thermoplastic polymers. Advantageously, when the polymer or mixture of polymers comprises carbon-containing fillers, such as carbon black or carbon nanofillers, preferably chosen from carbon nanofillers, in particular graphenes and / or carbon nanotubes and / or carbon nanofibrils or their mixtures, the effect of heating by induction or by microwaves is amplified by the presence of these charges which then lead the heat to the heart of the material.

Advantageously, each calender (51), (52), (53) of the device is coupled to a rapid heating device (41), (42), (43), located before and / or after each calender, in order to rapidly transmit thermal energy to the material and perfect the impregnation of the fibers with the molten polymer. The rapid heating device may for example be chosen from the following devices: a microwave or induction device, an IR or laser infrared device or other device allowing direct contact with the heat source such as a device with a flame or a hot gas. A microwave or induction device is very advantageous, in particular when it is coupled to the presence of carbon nanofillers in the polymer or polymer mixture since the carbon nanofillers amplify the heating effect and transmit it to the core of the material.

According to an alternative embodiment, it is also possible to combine several of these heating devices.

The method may further comprise a step of heating the wicks of the fibers, prior to said impregnation with, as a preferred heating means, heating by microwaves as for the heating system of said heating shell.

Optionally, a subsequent step is to wind the prepreg and shaped ribbons. For this, the unit (100) for implementing the method comprises a winding device (60) comprising as many coils (61) as ribbons, a coil (61) being assigned to each ribbon. A splitter (62) is generally provided to deflect the pre-impregnated ribbons to their respective coils (61), while preventing the ribbons from touching to avoid any degradation.

Figure 2 shows schematically the detail of the grooves (73) of a calender (70) sectional view. A calender (70) includes an upper roller (71) and a lower roller (75). One of the rollers, for example the upper roll (71), comprises a crenellated part (72), while the other roll, that is to say the lower roll (75) in the example, comprises a grooved part (76), the shape of the grooves being complementary to the shape of the projections (72) of the upper roll. The spacing E between the rollers (71), (75) and / or the pressure exerted by the two rollers against one another makes it possible to define the dimensions of the grooves 73), and in particular their thickness ep and width I. Each groove (73) is provided to house a fiber wick which is then pressed and heated between the rollers. The wicks then turn into parallel unidirectional ribbons whose thickness and width are calibrated by the grooves (73) of the calenders. Each calender advantageously comprises a plurality of grooves, the number of which can be up to 200, so as to produce as many ribbons as there are grooves and pre-impregnated locks. The calendering device further comprises a central device, referenced SYST in FIG. 1, controlled by a computer program provided for this purpose, which makes it possible to simultaneously regulate the pressure and / or the spacing of the calendering rollers of all the The one-way ribbon (s) thus manufactured has (s) a width I and a thickness ep adapted for robot removal in the manufacture of three-dimensional parts, without need to be split to the right width. The width of the ribbon (s) is advantageously between 5 and 400mm, preferably between 5 and 50mm, and even more preferably between 5 and 15mm.

The method of manufacturing a preimpregnated fibrous material which has just been described thus makes it possible to produce preimpregnated fibrous materials with high productivity, while permitting homogeneous impregnation of the fibers and the control and reproducibility of the porosity. , thus allowing control and reproducibility of the performance of the final composite article. The homogeneous impregnation around the fibers and the absence of porosities are ensured by the impregnation step in the tank by controlling the rate of projection of said powder by the gun (s) on said fibrous material, and "effect corner ", coupled with the simultaneous development of the wick at the compression roll or rolls. The materials obtained are semi-finished products in the form of ribbons calibrated in thickness and in width, and having a low porosity. The method thus makes it possible to produce calibrated ribbons of preimpregnated fibrous material suitable for the manufacture of composite parts in three dimensions, by automatically depositing said ribbons by means of a robot.

Advantageously, the thermoplastic polymer of the ribbon obtained with the process according to the invention is selected from amorphous polymers whose glass transition temperature is such that Tg> 80 ° C. and / or from semi-crystalline polymers whose melting temperature Tf is> 150 ° C.

Advantageously, said thermoplastic polymer is:

an aliphatic polyamide chosen from polyamide 6 (PA-6), polyamide 1 1 (PA-1 1), polyamide 1 2 (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), mixtures thereof and copolyamides of these, in particular 1010/1 1, 1010/12 etc ...

an aromatic polyamide, optionally modified with urea units, in particular a polyphthalamide, in particular a semi-aromatic polyamide of formula X / YAr, as described in EP1505099, in particular a semiaromatic polyamide of formula A / XT in which A is selected from a unit obtained from an amino acid, a unit obtained from a lactam and a unit having the formula (diamine Ca). (diacid in Cb), with a representing the number of carbon atoms of the diamine and b representing the number of carbon atoms of the diacid, a and b each being between 4 and 36, advantageously between 9 and 18;

XT denotes a unit obtained from the polycondensation of a diamine in Cx and terephthalic acid, with x representing the number of carbon atoms of the diamine in Cx, 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, 66 / 6T, 6I / 6T, PA1 1 / 10T, 1 1 / 6T / 10T, MXDT / 10T or MPMDT / 10T, BACT / 10T aramid, and block copolymers, especially polyamide / polyether (PEBA).

Advantageously, the fibrous material of the ribbon obtained with the process according to the invention is made of carbon fiber.

Advantageously, the thermoplastic polymer of the ribbon obtained with the process according to the invention is a semi-aromatic polyamide, in particular chosen from PA 1 1, PA 12, PA 1 1/1010, PA 12/1010, PA 1 1 / 10T, PA 1 1 / 6T / 10T, PA MXDT / 10T, PA MPMDT / 10T and PA BACT / 10T and the fibrous material of the ribbon obtained with the process according to the invention is carbon fiber.

Advantageously, said tape whose thermoplastic polymer is a polyamide chosen from PA 1 1, PA 12, PA 1 1/1010, PA 12/1010, PA 1 1 / 10T, PA 1 1 / 6T / 10T, PA MXDT / 10T, PA MPMDT / 10T and PA BACT / 10T is used for civil or military aeronautics or automotive.

Advantageously, the thermoplastic polymer of the ribbon obtained with the process according to the invention is PEKK.

Advantageously, the thermoplastic polymer of the ribbon obtained with the process according to the invention is PEKK and the fibrous material of the ribbon obtained with the process according to the invention is made of carbon fiber.

Advantageously, the thermoplastic polymer of the ribbon obtained with the process according to the invention is PEI.

Advantageously, the thermoplastic polymer of the ribbon obtained with the process according to the invention is PEI and the fibrous material of the ribbon obtained with the process according to the invention is made of carbon fiber.

Advantageously, the thermoplastic polymer of the ribbon obtained with the process according to the invention is a mixture of PEKK and PEI, preferably 90-10% to 60-40%, in particular 90-10% to 70-30% by weight. Advantageously , the fibrous material of the ribbon obtained with the process according to the invention is made of carbon fiber.

Advantageously, the thermoplastic polymer of the ribbon obtained with the process according to the invention is a mixture of PEKK and PEI and the fibrous material of the ribbon obtained with the process according to the invention is made of carbon fiber.

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

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 aeronautical, nautical, railway; renewable energies, in particular wind turbines, tidal turbines, energy storage devices, solar panels; thermal protection panels; sports and recreation, health and medical, ballistics with weapon or missile parts, 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 tape of preimpregnated fibrous material as defined above. Advantageous embodiments of the method of the invention

Advantageously, the fibrous material is chosen from carbon fiber and fiberglass.

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, in particular especially a PA 1 1 / 10T, a PA 1 1 / 6T / 10T, a PA MXDT / 10T or a PA MPMDT / 10T, or PA BACT / 10T, PEKK and PEI or a mixture thereof. Advantageously, the thermoplastic polymer used for impregnating 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, in particular particularly a PA 1 1 / 10T, a PA 1 1 / 6T / 10T, a PA MXDT / 10T, a PA MPMDT / 10T, or PA BACT / 10T, PEKK and PEI or a mixture thereof.

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

Table I below groups advantageous embodiments according to the method of the invention carried out in a tank for a carbon fiber or fiberglass wick with one or more cylindrical compression rolls (s) not fluted:

Material Mode Number of Flow Rate

fibrous realization Polymer projection rollers Angle ai (°) No. (fiber of ..) compression (g / min)

1 Carbon Polyamide 1 10 to 400 5 to 85

2 Carbon Polyamide 1 10 to 400 5 to 45

3 Carbon Polyamide 1 10 to 400 5 to 30 Carbon Polyamide 1 25 to 150 5 to 85

Carbon Polyamide 1 25 to 150 5 to 45

Carbon Polyamide 1 25 to 150 5 to 30

Carbon Polyamide 2 10 to 400 5 to 85

Carbon Polyamide 2 10 to 400 5 to 45

Carbon Polyamide 2 10 to 400 5 to 30

Carbon Polyamide 2 25 to 150 5 to 85

Carbon Polyamide 2 25 to 150 5 to 45

Carbon Polyamide 2 25 to 150 5 to 30

Carbon Polyamide 3 10 to 400 5 to 85

Carbon Polyamide 3 10 to 400 5 to 45

Carbon Polyamide 3 10 to 400 5 to 30

Carbon Polyamide 3 25 to 150 5 to 85

Carbon Polyamide 3 25 to 150 5 to 45

Carbon Polyamide 3 25 to 150 5 to 30

Carbon PEKK ¹ 10 to 400 5 to 85

Carbon PEKK ¹ 10 to 400 5 to 45

Carbon PEKK ¹ 10 to 400 5 to 30

Carbon PEKK ¹ 25 to 150 5 to 85

Carbon PEKK ¹ 25 to 150 5 to 45

Carbon PEKK ¹ 25 to 150 5 to 30

Carbon PEKK 2 10 to 400 5 to 85

Carbon PEKK 2 10 to 400 5 to 45

Carbon PEKK 2 10 to 400 5 to 30

Carbon PEKK 2 25 to 150 5 to 85

Carbon PEKK 2 25 to 150 5 to 45

Carbon PEKK 2 25 to 150 5 to 30

Carbon PEKK 3 10 to 400 5 to 85

Carbon PEKK 3 10 to 400 5 to 45

Carbon PEKK 3 10 to 400 5 to 30

Carbon PEKK 3 25 to 150 5 to 85

Carbon PEKK 3 25 to 150 5 to 45

Carbon PEKK 3 25 to 150 5 to 30 Carbon PEI 10 to 400 5 to 85

Carbon PEI ¹ 10 to 400 5 to 45

Carbon PEI ¹ 10 to 400 5 to 30

Carbon PEI ¹ 25 to 150 5 to 85

Carbon PEI ¹ 25 to 150 5 to 45

Carbon PEI ¹ 25 to 150 5 to 30

Carbon PEI 2 10 to 400 5 to 85

Carbon PEI 2 10 to 400 5 to 45

Carbon PEI 2 10 to 400 5 to 30

Carbon PEI 2 25 to 150 5 to 85

Carbon PEI 2 25 to 150 5 to 45

Carbon PEI 2 25 to 150 5 to 30

Carbon PEI 3 10 to 400 5 to 85

Carbon PEI 3 10 to 400 5 to 45

Carbon PEI 3 10 to 400 5 to 30

Carbon PEI 3 25 to 150 5 to 85

Carbon PEI 3 25 to 150 5 to 45

Carbon PEI 3 25 to 150 5 to 30

Carbon PEI ¹ 10 to 400 5 to 85

Carbon PEI ¹ 10 to 400 5 to 45

Carbon PEI ¹ 10 to 400 5 to 30

Carbon PEI ¹ 25 to 150 5 to 85

Carbon PEI ¹ 25 to 150 5 to 45

Carbon PEI ¹ 25 to 150 5 to 30

Carbon PEI 2 10 to 400 5 to 85

Carbon PEI 2 10 to 400 5 to 45

Carbon PEI 2 10 to 400 5 to 30

Carbon PEI 2 25 to 150 5 to 85

Carbon PEI 2 25 to 150 5 to 45

Carbon PEI 2 25 to 150 5 to 30

Carbon PEI 3 10 to 400 5 to 85

Carbon PEI 3 10 to 400 5 to 45

Carbon PEI 3 10 to 400 5 to 30 Carbon PEI 3 25 to 150 5 to 85

Carbon PEI 3 25 to 150 5 to 45

Carbon PEI 3 25 to 150 5 to 30

Polyamide glass ¹ 10 to 400 5 to 85

Polyamide glass ¹ 10 to 400 5 to 45

Polyamide glass ¹ 10 to 400 5 to 30

Polyamide glass ¹ 25 to 150 5 to 85

Polyamide glass ¹ 25 to 150 5 to 45

Polyamide glass ¹ 25 to 150 5 to 30

Polyamide glass 2 10 to 400 5 to 85

Polyamide glass 2 10 to 400 5 to 45

Polyamide glass 2 10 to 400 5 to 30

Polyamide glass 2 25 to 150 5 to 85

Polyamide glass 2 25 to 150 5 to 45

Polyamide glass 2 25 to 150 5 to 30

Polyamide glass 3 10 to 400 5 to 85

Polyamide glass 3 10 to 400 5 to 45

Polyamide glass 3 10 to 400 5 to 30

Polyamide glass 3 25 to 150 5 to 85

Polyamide glass 3 25 to 150 5 to 45

Polyamide glass 3 25 to 150 5 to 30

PEKK glass ¹ 10 to 400 5 to 85

PEKK glass ¹ 10 to 400 5 to 45

PEKK glass ¹ 10 to 400 5 to 30

PEKK glass ¹ 25 to 150 5 to 85

PEKK glass ¹ 25 to 150 5 to 45

PEKK glass ¹ 25 to 150 5 to 30

PEKK glass 2 10 to 400 5 to 85

PEKK glass 2 10 to 400 5 to 45

PEKK glass 2 10 to 400 5 to 30

PEKK glass 2 25 to 150 5 to 85

PEKK glass 2 25 to 150 5 to 45

PEKK glass 2 25 to 150 5 to 30 103 PEKK glass 3 10 to 400 5 to 85

104 PEKK glass 3 10 to 400 5 to 45

105 PEKK glass 3 10 to 400 5 to 30

106 PEKK glass 3 25 to 150 5 to 85

107 Glass PEKK 3 25 to 150 5 to 45

108 PEKK glass 3 25 to 150 5 to 30

109 Glass PEI ¹ 10 to 400 5 to 85

1 10 Glass PEI ¹ 10 to 400 5 to 45

1 1 1 Glass PEI ¹ 10 to 400 5 to 30

1 12 Glass PEI ¹ 25 to 150 5 to 85

1 13 Glass PEI ¹ 25 to 150 5 to 45

1 14 Glass PEI ¹ 25 to 150 5 to 30

1 Glass PEI 2 10 to 400 5 to 85

1 16 Glass PEI 2 10 to 400 5 to 45

1 17 Glass PEI 2 10 to 400 5 to 30

1 18 Glass PEI 2 25 to 150 5 to 85

1 19 Glass PEI 2 25 to 150 5 to 45

120 PEI glass 2 25 to 150 5 to 30

121 Glass PEI 3 10 to 400 5 to 85

122 Glass PEI 3 10 to 400 5 to 45

123 PEI glass 3 10 to 400 5 to 30

124 Glass PEI 3 25 to 150 5 to 85

125 Glass PEI 3 25 to 150 5 to 45

126 PEI glass 3 25 to 150 5 to 30

127 Glass PEI ¹ 10 to 400 5 to 85

128 Glass PEI ¹ 10 to 400 5 to 45

129 PEI glass ¹ 10 to 400 5 to 30

130 Glass PEI ¹ 25 to 150 5 to 85

131 PEI glass ¹ 25 to 150 5 to 45

132 Glass PEI ¹ 25 to 150 5 to 30

133 Glass PEI 2 10 to 400 5 to 85

134 Glass PEI 2 10 to 400 5 to 45

135 Glass PEI 2 10 to 400 5 to 30 136 Glass PEI 2 25 to 150 5 to 85

137 Glass PEI 2 25 to 150 5 to 45

138 Glass PEI 2 25 to 150 5 to 30

139 Glass PEI 3 10 to 400 5 to 85

140 Glass PEI 3 10 to 400 5 to 45

141 Glass PEI 3 10 to 400 5 to 30

142 Glass PEI 3 25 to 150 5 to 85

143 Glass PEI 3 25 to 150 5 to 45

144 Glass PEI 3 25 to 150 5 to 30

TABLE I

In embodiments comprising PEKK or PEI, the PEKK may be in admixture with PEI and the PEI may be in admixture with PEKK in the proportions defined above.

Advantageously, in the compositions of Table I above defined in which two compression rollers are present in the tank, the roller R2 is above the roller Ri relative to the bottom of the tank, in particular H2-H1 is included in 1 cm to 30 cm, preferably 1 to 10 cm, in particular from 1 cm to 3 cm, in particular about 2 cm, and the angle O 2 is from 0 to 90 °, in particular from 25 to 45 ° C., in particular from 25 to 45.degree. at 35 ° and the wick passes above R2.

These embodiments correspond to FIG.

Advantageously, in the compositions of Table I above defined in which two compression rollers are present in the tank, the roller R2 is above the roller Ri relative to the bottom of the tank, in particular H2-H1 is included in 1 cm to 30 cm, especially about 2 cm and the angle O 2 is from 90 to 180 ° C, in particular from 1 to 135 °, in particular from 1 to 125 °, and the lock passes below R2.

Description of figures

Figure 1 shows a diagram of an implementation unit of the method of manufacturing a preimpregnated 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. Figure 3 details a tank (20) with a height-adjustable, height-adjustable bartack (82). The edge of the tank inlet is equipped with a rotating roller 83a on which the wick 81a runs and the edge of the tank outlet is equipped with a rotary roller 83b on which the wick 81b runs.

Fig. 4 shows a single compression roll embodiment, with a vat (20) including a powder spray gun (84) in which a single cylindrical compression roll is present and showing the angle CM.

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

FIG. 5 shows an embodiment, without being limited thereto, to two compression rollers R 1 and R 2, R 1 preceding R 2, with a vessel (20) each comprising a powder projection gun (84) (85) and wherein the two cylindrical compression rolls are at different heights from the bottom of the vessel (R2 at a height H2 above Ri at a height H1) are present and showing the angle CM and O2.

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

FIG. 6 shows an exemplary embodiment with a tank (20) comprising a powder spray gun (84) in which the two compression rollers R 1 and R 2 are cylindrical, at the same level relative to one another. at the other and side by side and showing the angle CM, and the angle 02 = 0 ° and the wick passing between the 2 rolls)

FIG. 7 shows an exemplary embodiment with a tank (20) each comprising a powder spray gun (84) and in which the two compression rollers R 1 and R 2 are cylindrical, at the same level one relative to each other and side by side and showing the angle CM, and the angle 02 = 90 ° and the wick passing below R2.

FIG. 8 shows an exemplary embodiment with a tank (20) each comprising a powder spray gun (84) and in which two cylindrical compression rolls R 1 and R 2, R 1 preceding R 2, at different levels. are present and showing the angle CM and 02 and the wick passing under the roller R2.

FIG. 9 shows an embodiment with a tank (20) with two compression rollers R 1 and R 2, R 1 preceding R 2, each comprising a spray gun spraying (84) powder (85) and a compression roll R3 comprising a powder spraying gun (84) (85) and showing the angles CM, 02 and 03.

FIG. 10 shows a photograph taken under a scanning electron microscope of a sectional view of a carbon fiber wick ¼ "Toray carbon fiber, 12K T700S MOE impregnated with a PA1 1 / 6T / 10T polyamide powder of D50 = Ι ΟΌμιτι according to the process described in WO 2015/121583 (after calendering).

The method according to WO 2015/121583 shows a lack of homogeneity in several places of the pre-impregnated wick schematically represented by the white arrows.

FIG. 11 shows a photograph taken under a scanning electron microscope of a sectional view of a ¼ "carbon fiber wick (Toray fiber 12K T700S MOE), impregnated with a polyamide powder PA MPMDT / 10T of D50 = 1 15μηη according to the process of the invention (as described in Example 2, after calendering).

Figure 12 shows the impregnation of flax fibers with melt-processed PA1 1 as a comparative example with the process of the invention (Example 2). FIG. 13 shows the impregnation of Toray T700 S 24K 60E carbon fibers with MPMDT / 10T (D50 = 1 15 m) obtained by melting as a comparative example with the process of the invention (Example 2 ). The following examples illustrate in a nonlimiting manner the scope of the invention.

Example 1 (Comparative Example):

A 12K carbon fiber wick was impregnated with 1 1 / 6T / 10T PA as described in WO 2015/121583.

D50 = 100μΜ.

Results:

The results are presented in FIG. 10 and show a lack of homogeneity in several places of the pre-impregnated wick shown schematically by the white arrows. Example 2: general procedure for impregnating a fibrous material with a polyamide powder in tank with a single roller

The following procedure was performed:

A cylindrical compression roller in the tank (L = 500 mm, l = 500mm, H = 600mm), diameter 25 mm. Projection rate 25-30g / min

Angle in 25 °

Bloom about 100% (2 times the width) for 1/4 "Toray carbon fiber carbon fiber wick, 12K T700S MOE

- D50 = 1 15 μηη (Ο10 = 49μηη, D90 = 207 m) for the MPMDT / 10T powder. edge of the tank equipped with a fixed roller.

The fibrous material (¼ "carbon fiber wick) pre-impregnated with a polyamide (MPMDT / 10T) was prepared according to this procedure and is shown in FIG. 1. This demonstrates the effectiveness of the powder impregnation process. Dry in the tank with a compression roller and control of the powder spray rate.

Example 3: Determination of the porosity ratio the relative difference between theoretical density and experimental density (general method)

a) The required data are:

The density of the thermoplastic matrix

The density of the fibers

The weight of the reinforcement:

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

• mass per unit area (g / m ² ) for example for a wider slab or fabric b) Measures to be carried out:

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

The measures to be carried out are:

The size of the samples taken:

o Length (if known linear density),

o Length and width (if known mass per unit area).

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 (TGA) as determined for example in 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 ratio:

a) Determination of the theoretical mass fiber ratio:

m ,. The

= ^{1 1 c} air

With

mid linear mass of the tape,

L the length of the sample and

_Me ir \ a mass of the sample measured in air.

The variation of the mass ratio of fibers is supposed to be directly related to a variation of the matrix level without taking into account the variation of the quantity of the fibers in the reinforcement.

Determination of the theoretical density dm = ^~ % Mf _th ,% Mf _th

d _m d. †

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

The theoretical density thus calculated is the accessible density 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

A process for manufacturing a preimpregnated fibrous material comprising a continuous fiber fibrous material and at least one thermoplastic polymer matrix, characterized in that said preimpregnated fibrous material is made of a single unidirectional ribbon or a plurality of parallel ribbons unidirectional and in that said method comprises a step of impregnation, in particular at heart and homogeneous, of said fibrous material in the form of a wick (81 a) or of several parallel locks by said at least one thermoplastic polymer matrix is in the form of a powder, said impregnation step being carried out by spraying said powder by a nozzle (or nozzles) or a gun (s) by dry route in a tank (20) on said material fibrous and controlling the rate of said at least one thermoplastic polymer matrix in said fibrous material being effected by control of the flow of projec said powder is provided by said at least one nozzle (s) or gun (s) on said fibrous material, excluding any electrostatic process in voluntary charge.

A method according to claim 1, characterized in that said tank (20) comprises at least one docking piece (82), said wick (81a) or said wicks being in contact with a part or the whole of the surface of said at least one mating piece (82), and the powder projection is performed at the inlet of said mating piece (82).

Process according to claim 1 or 2, characterized in that the level of fibers in said impregnated fibrous material is 45 to 65% by volume, preferably 50 to 60% by volume, especially 54 to 60%.

Method according to one of claims 1 to 3, characterized in that the rate of projection of said powder by said nozzle (s) or said (or said) gun (s) on said fibrous material is comprised of 10 g / min at 400 g / min, in particular 20 to 150 g / min.

5. Method according to one of claims 1 to 4, characterized in that said impregnation step is carried out with simultaneous expansion of said wick (81 a) or said wicks between the inlet and the outlet of said vessel (20). .

6. Method according to claim 5, characterized in that said expansion of said wick (81 a) or said wicks is performed at least at said at least one part of the docking (82).

7. The method of claim 2 or 6, characterized in that said at least one mating piece (82) is a convex compression roller, concave or cylindrical.

8. Method according to claim 7, characterized in that said at least one compression roller is of cylindrical shape and the percentage of expansion of said wick (81 a) or said wicks between the inlet and the outlet of said vessel ( 20) being between 1% and 400%, preferably between 30% and 400%, preferably between 30% and 150%, preferably between 50% and 150%.

9. A method according to claim 8, characterized in that a single compression roll is present in said tank (20) and said impregnation is performed at the angle ai formed by said wick (81 a) or said wicks between input of said compression roller and the vertical tangent to said compression roller.

10. The method of claim 9, characterized in that the angle α is from 0 to 89 °, preferably 5 ° to 85 °, preferably from 5 ° to 45 °, preferably from 5 ° to 30 °.

1 1. Process according to Claim 8, characterized in that two compression rollers R 1 and R 2 are present in said vessel (20) and said impregnation is carried out at the angle α 1 formed by said wick (81 a) or said wicks between input of said compression roll Ri and the vertical tangent to said compression roller and / or at the angle a2 formed by said wick (81 a) or said wicks between the inlet of said compression roller R2 and the vertical tangent to said compression roller R2, said roller compression R 1 (in the running direction of the process) preceding said compression roller R2 and said wick (81 a) or said wick being able to pass above or below the roller R2.

12. The method of claim 1 1, characterized in that the two compression rollers Ri and R2 are 0.15 mm apart to the length equivalent to the maximum dimension of the vessel (20), preferably 10 mm to 50 mm and in that the difference in height between the two compression rollers R 1 and R 2 is from 0 to the height corresponding to the maximum height of the vessel (20) subtracted from the diameters of the two compression rollers, preferably from 0, 15 mm at the height corresponding to the maximum height of the vessel (20) subtracted diameters of the two compression rollers, more preferably to a difference in height of between 10 mm and 300 mm, R2 being the upper compression roll.

13. Method according to one of claims 1 to 12, characterized in that it further comprises a step of shaping said wick (81 a) or said parallel locks of said impregnated fibrous material, by calendering by means of at least one heater (51, 52, 53) heating in the form of a single unidirectional ribbon or a plurality of unidirectional parallel ribbons with, in the latter case, said heating calender comprising a plurality of grooves (73) for calendering, preferably up to 200 calendering grooves, in accordance with the number of said ribbons and with a pressure and / or spacing between the rolls of said calender controlled by a slave system.

Method according to claim 13, characterized in that the calendering step is carried out by means of a plurality of calenders (51, 52, 53). heating, mounted in parallel and / or in series with respect to the direction of travel of the wicks (81 a) of fibers.

15. Method according to one of claims 13 or 14, characterized in that said (or said) calender (s) heater (s) comprises (include) an integrated heating system by induction or by microwaves, preferably by microwaves, coupled to the presence of carbonaceous fillers in said thermoplastic polymer or thermoplastic polymer blend.

16. Method according to one of claims 13 to 15, characterized in that said (or said) calender (s) heating (s) is (are) coupled (s) to a rapid complementary 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 to the presence of carbonaceous fillers in said polymer or in said polymer mixture, or an IR infrared heater, or Laser or by direct contact with another heat source such as a flame or a hot gas. 17. Method according to one of claims 1 to 16, characterized in that said impregnation step (s) is (are) completed by a step of recovery of said single wick (81 a) or of said plurality of parallel wicks after 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 a powder in the tank (20), said molten polymer being preferably of the same nature as said polymer in the form of a powder in the tank (20), preferably with said covering being effected by extrusion at right angles to said single wick (81 a) or to said plurality of parallel locks .

18. Method according to one of claims 1 to 17, characterized in that said thermoplastic polymer further comprises carbonaceous fillers, in particular carbon black or carbon nanofillers, preferably selected from carbon nanofillers, in particular graphenes and / or carbon nanotubes and / or carbon nanofibrils or mixtures thereof.

19. Method according to one of claims 1 to 18, characterized in that said thermoplastic polymer further comprises liquid crystal polymers or cyclized poly (butylene terephthalate), or mixtures containing it as additives.

20. Method according to one of claims 1 to 19, characterized in that said at least one thermoplastic polymer is selected from: polyaryl ether ketones (PAEK), in particular poly (ether ether ketone) (PEEK); polyaryl ether ketone ketone (PAEKK), in particular poly (ether ketone ketone) (PEKK); aromatic polyetherimides (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 mixtures thereof, especially a mixture of PEKK and PEI, preferably 90-10% to 60-40%, especially 90-10% to 70-30% by weight.

21. Process according to claim 20, characterized in that said at least one thermoplastic polymer is a polymer whose glass transition temperature is such that Tg> 80 ° C or a semicrystalline polymer whose melting temperature Tf> 150 ° C.

22. Method according to one of claims 1 to 21, characterized in that said fibrous material comprises continuous fibers selected from carbon fibers, glass, silicon carbide, basalt, silica, natural fibers in particular flax or hemp, lignin, bamboo, sisal, silk, or cellulosic, especially viscose, or amorphous thermoplastic fibers of glass transition temperature Tg greater than the Tg of said polymer or said polymer mixture when the latter is amorphous or greater than the Tf of said polymer or said mixture of polymers when the latter is semi-crystalline, or semi-crystalline thermoplastic fibers with a melting temperature Tf greater than the Tg of said polymer or said polymer mixture when the latter is amorphous or greater than the Tf of said polymer or said polymer mixture when the latter is semi-crystalline, or a mixture of two or more of said fibers, preferably a mixture of carbon fibers, glass or silicon carbide, in particular carbon fibers.

23. Unidirectional tape of preimpregnated fibrous material, in particular tape wound on a reel, characterized in that it is obtained by a process as defined according to one of claims 1 to 22.

24. Tape according to claim 23, characterized in that it has a width (I) and a thickness (ep) adapted to robot removal in the manufacture of parts in three dimensions, without the need for slitting, and preferably to a width (I) of at least 5 mm and up to 400 mm, preferably between 5 and 50 mm and even more preferably between 5 and 15 mm.

25. Tape according to one of claims 23 or 24, characterized in that the thermoplastic polymer is a polyamide chosen from in particular an aliphatic polyamide such as PA 1 1, PA 12, 1 1/1010 or 12/1010 or a semi polyamide -aromatic chosen from PA 1 1 / 10T, PA 1 1 / 6T / 10T, PA MXDT / 10T, PA MPMDT / 10T and PA BACT / 10T. 26. Use of the method as defined in one of claims 1 to 22, for the manufacture of calibrated ribbons suitable for the manufacture of composite parts in three dimensions, by automatic removal of said ribbons by means of a robot.

27. Use of the ribbon of preimpregnated fibrous material, as defined in claim 23 or 24, in the manufacture of composite parts in three dimensions. 28. Use according to claim 27, characterized in that said manufacture of said composite parts relates to the fields of transport, in particular automobile, oil and gas, in particular offshore, gas storage, civil aviation or military, nautical , rail; renewable energy, in particular wind turbine, tidal turbine, energy storage devices, solar panels; thermal protection panels; sports and recreation, health and medical, ballistics with weapon or missile parts, security and electronics.

29. A three-dimensional composite part, characterized in that it results from the use of at least one unidirectional tape preimpregnated fibrous material as defined in claim 23 or 24.