FIBROUS MATERIAL IMPREGNATED WITH THERMOPLASTIC POLYMER HAVING OPTIMAL MOLECULAR WEIGHT AND VISCOSITY, AND PROCESS FOR ITS PREPARATION

Description

Technical field

[0001] The present invention relates to a fibrous material impregnated with an amorphous or semi-crystalline thermoplastic polymer matrix whose glass transition temperature is such that Tg ≥ 40°C, in particular Tg ≥ 100°C, in particular ≥ 120°C, said impregnated fibrous material having a fiber content of 45 to 65% by volume, preferably 50 to 60% by volume, in particular 54 to 60% by volume, the number-average molecular weight Mn of said thermoplastic polymer being in the range 11000 to 25000 g / mol, the melt viscosity of said thermoplastic polymer being in the range 80 to 1500 Pa.s, as measured in plane-plane rheology under 1 Hz and 2% deformation, at a temperature of Tg + 220°C.

[0002] More particularly, the invention aims to provide an impregnated fibrous material as defined above and whose poly-molecularity index Ip of said thermoplastic polymer is from 2 to 6, in particular, 2 to 3.5, notably from 2.5 to 3.5.

[0003] The invention also relates to the process for preparing said fibrous material and to its use for the manufacture of composite parts, in particular by automatic deposition using a robot or by filament winding.

[0004] In this description, the term "fibrous material" means an assembly of individual reinforcing fibers. After impregnation with resin, it is in the form of a ribbon (tape) or a sheet or a pultruded plate.

[0005] Ribbon (or tape) means a strip which is a semi-finished product of low thickness, not calibrated in width or thickness, and composed of a single strand of fibers, or a thin band composed of one or more strands of fibers, calibrated in thickness and width.

[0006] This fibrous material can also be only pre-impregnated by the resin leading to a flexible semi-finished product generally in the form of fabrics or ncf which will be assembled and consolidated to make a thermoformable composite plate or directly positioned in a mold to make the final part.

[0007] Such pre-impregnated or impregnated fibrous materials are particularly intended for the production of lightweight composite materials for the manufacture of mechanical parts having a three-dimensional structure and possessing good mechanical and thermal properties. When the fibers are made of carbon and / or the resin is loaded with suitable additives, these fibrous materials are capable of discharging electrostatic charges. The use of flame-retardant resins or flame-retardant additives in non-flame-retardant resins allows the impregnated fibrous materials to be fire-resistant. They therefore have properties compatible with the manufacture of parts in particular in the fields of mechanics, aeronautics, nautical, automotive, oil and gas, in particular offshore, gas storage, energy, health and medicine, sports and leisure and electronics.

[0008] Such impregnated fibrous materials are also called composite materials. They comprise the fibrous material, consisting of the reinforcing fibers, and a matrix consisting of the polymer impregnating the fibers. The primary role of this matrix is to keep the reinforcing fibers in a compact form and to give the desired shape to the final product. This matrix also ensures load transfer between the fibers and therefore determines the mechanical strength of the composite. Such a matrix also serves to protect the reinforcing fibers against abrasion and an aggressive environment, to control the surface appearance and to disperse any loads between the fibers. The role of this matrix is important for the long-term performance of the composite material, particularly with regard to fatigue and creep. State of the art

[0009] Good quality of three-dimensional composite parts manufactured from impregnated fibrous materials requires in particular mastery of the pre-impregnation process or impregnation of the reinforcing fibers with the thermoplastic polymer and therefore of the final impregnated fibrous material obtained.

[0010] The disadvantages of the state of the art consist of the difficulty of obtaining good impregnation of the fibers, while having good mechanical properties. Such a compromise is difficult to achieve, because to have good mechanical properties, the molar mass must be high, which implies a high viscosity.

[0011] Thus, the molar mass influences the Tg value of the resin and the Tg increases with the molar mass, until reaching a plateau regime in which the Tg no longer varies significantly. The Tg influences to the 1st order the mechanical properties of the resin, in particular its modulus and the temperature stability of this modulus: it is customary to use the composite only up to a maximum temperature equal to Tg -10 to -30°C.

[0012] As the molar mass increases, the fracture toughness of the composite also increases, but the melt viscosity of the resin increases and makes the impregnation of fibers and then the final consolidation of the composite part more difficult, since at this stage, movements of fibers and resin are necessary to fill the porosities, particularly between the tape and intertapes.

[0013] This problem is further increased when the Tg of the polymer is high since the viscosity depends on the difference between the processing temperature and the Tg of the polymer.

[0014] Until now, the manufacture of ribbons of fibrous materials reinforced by impregnation of thermoplastic polymer or thermosetting polymer was carried out using several processes which depend in particular on the nature of the polymer, the type of final composite material desired and its field of applications, some of these processes consisting of an impregnation step followed by a hot calendering step of the impregnated fibrous material or a drying step possibly followed by a step of melting the thermoplastic polymer.

[0015] Thus, wet impregnation technologies or those using a liquid or very low viscosity precursor, polymerizing in situ, are often used to impregnate reinforcing fibers with thermosetting polymers, such as epoxy resins for example, as described in patent WO2012 / 066241A2. These technologies are generally not directly applicable to impregnation with thermoplastic polymers, because these rarely have liquid precursors.

[0016] Current techniques for impregnating fibrous materials and for shaping such impregnated fibrous materials into calibrated ribbons therefore have several drawbacks. For example, it is difficult to heat a molten mixture of thermoplastic polymers homogeneously in a die and at the die outlet, to the core of the material, which alters the quality of the impregnation. In addition, the temperature difference existing between the fibers and a molten mixture of polymers in an oven, particularly an infrared oven, also alters the quality and homogeneity of the impregnation. In addition, this method of melt impregnation does not allow high fiber rates or high production speeds to be obtained because of the high viscosity of thermoplastic resins, particularly when they have high glass transition temperatures, which is necessary for obtaining high-performance composite materials.

[0017] In particular, extrusion impregnation processes for molten polymers are suitable for the use of low-viscosity thermoplastic polymers only. Thermoplastic polymers, particularly those with a high glass transition temperature, therefore have a melt viscosity that is too high to allow satisfactory impregnation of fibers and good quality semi-finished or finished products.

[0018] In this case, it is necessary to use prepolymers, whether they are reactive on themselves or reactive between them, or a prepolymer and a chain extender, to carry out the pre-impregnation with a fluid product, easy to impregnate, then to heat the pre-impregnated product in order to finalize the impregnation.

[0019] However, the use of prepolymers has other disadvantages, and in particular the prepolymers must have slow enough kinetics to allow impregnation but also fast enough kinetics to allow manufacturing compatible with an industrial rate. This requires a compromise that is sometimes difficult to achieve. Presentation of the invention

[0020] The invention therefore aims to remedy at least one of the drawbacks of the prior art and in particular aims to obtain an impregnated fibrous material as defined above with a thermoplastic polymer matrix whose three parameters, viscosity in the molten state, processing temperature and weight-average molecular mass, are chosen optimally so as to allow the use of a non-reactive thermoplastic polymer and not a polymer derived from reactive precursors (prepolymers or monomers), thus making it possible to avoid the drawbacks presented by said prepolymers or monomers. Description of the embodiments

[0021] For this purpose, the subject of the invention is an impregnated fibrous material comprising at least one fibrous material in continuous fibers in the form of a strand or several parallel strands and at least one thermoplastic polymer matrix, characterized in that said at least one thermoplastic polymer is an amorphous or semi-crystalline polymer whose glass transition temperature is such that Tg ≥ 40°C, in particular Tg ≥ 100°C, in particular ≥ 120°C, the fiber content in said impregnated fibrous material being from 45 to 65% by volume, preferably from 50 to 60% by volume, in particular from 54 to 60% by volume, the number-average molecular weight Mn of said thermoplastic polymer being from 11,000 to 25,000 g / mol, the melt viscosity of said thermoplastic polymer being from 80 to 1,500 Pa.s, as measured in plane-plane rheology under 1 Hz and 2% deformation, at a temperature of Tg + 220°C.

[0022] The glass transition temperature Tg of the thermoplastic polymer matrix is measured using a differential scanning calorimeter (DSC), after a second heating pass, according to ISO 11357-2:2013. The heating and cooling rate is 20°C / min.

[0023] The inventors have therefore found that a non-reactive thermoplastic polymer which has a particular viscosity in the molten state at the processing temperature of said fibrous material polymer and a weight-average molecular mass makes it possible to impregnate a fibrous material without the need to use a polymer derived from reactive precursors (prepolymers or monomers), thus leading to the production of an impregnated fibrous material having an excellent compromise between the quality of impregnation, compatibility with non-autoclave consolidation techniques and mechanical properties.

[0024] In other words, the inventors found that to have good impregnation of a fibrous material it was necessary to be at a glass transition temperature Tg + 220°C, which makes it possible to obtain an adequate transformation or processing temperature to have not only good viscosity in the molten state but also a sufficient weight-average molecular mass to guarantee good mechanical properties.

[0025] Initially, the different proportions of monomers constituting the polymer are chosen to achieve a weight-average molar mass of at least 11,000 g / mol and less than 25,000 g / mol, for example with the use of chain limiters which allow the control of the molecular mass of the polymer, which makes it possible to obtain a polymer which, after impregnation of a fibrous material, will make it possible to obtain a composite having good mechanical properties without disturbing the impregnation of said fibrous material at the transformation or processing temperature at Tg + 220°C due to the viscosity in the molten state obtained at this temperature of 80 to 1500 Pa.s.

[0026] Thus, if we consider a transformation or processing temperature equal to Tg + 150°C, the melt viscosity at this temperature will be less fluid, compared to that obtained at a temperature Tg + 220°C. Nevertheless, even if the melt viscosity is in the claimed range of 80 to 1500 Pa.s, the number-average molecular mass obtained will then be lower than the critical number-average molecular mass which must be between 11000 and 25000 g / mol and the impregnation will not be correct.

[0027] On the contrary, at Tg beyond Tg + 220°C, there is then a risk of degradation of the product at this temperature and consequently the product obtained will present unsatisfactory mechanical properties despite a correct molecular mass and good viscosity.

[0028] It is therefore a compromise between three factors: the transformation or implementation temperature, i.e. Tg + 220°C, the viscosity, i.e. 80 to 1500 Pa.s and the critical number average molecular mass which must be between 11000 and 25000 g / mol.

[0029] The expression "non-reactive thermoplastic polymer" means that the thermoplastic polymer has a molecular weight which is no longer likely to change significantly, i.e. its number-average molecular mass (Mn) changes by less than 20% during its processing and therefore corresponds to the final polyamide polymer of the thermoplastic matrix.

[0030] The number (Mn) and weight (Mw) molar mass of the polymers was determined by size exclusion chromatography according to ISO 16014-1:2012, 16014-2:2012 and 16014-3:2012 using the following conditions: Device: Waters Alliance 2695 instrument Solvent: Hexafluoroisopropanol stabilized with 0.05M potassium trifluoroacetate Flow rate: 1 ml / minute Column temperature: 40°C. Two columns in series: 1000 Å PFG and 100 Å PFG (PPS) Sample concentration: 1 g / L (dissolution at room temperature for 24 h) Sample filtration using a syringe fitted with an ACRODISC PTFE filter, diameter 25mm, porosity 0.2 µm Injection volume: 100µl Refractometric detection at 40°C with UV detection at 228 nm

[0031] Calibration by PMMA standards from 1,900,000 to 402 g.mol-1. Calibration curve modeled by a fifth-degree polynomial.

[0032] Melt viscosity is measured by oscillatory rheology at a temperature Tg +220°C, on a Physica MCR301 device between two parallel planes of 25 mm diameter. The viscosity measurement is carried out over a maximum time of ten minutes.

[0033] It is obvious that the non-reactive thermoplastic polymer must be stable at the melt viscosity measurement temperature.

[0034] In the event that said thermoplastic polymer is not stable at this temperature, it is then necessary to stabilize the polymers, in particular by an antioxidant or a mixture of antioxidants in a proportion by weight relative to the thermoplastic polymer of 0.1 to 4%, in particular of 0.1 to 1%.

[0035] Advantageously, the antioxidant is chosen from hindered phenols, such as Irganox ®< (BASF) or BHT (butylated hydroxytoluene), secondary aromatic amines such as alkylated diphenylamines, phosphites such as Tris(2,4-di-tert-butylphenyl)phosphite or Irgafos ®< (CIBA).

[0036] Advantageously, the difference between the melting temperature Tf of said at least one semi-crystalline thermoplastic polymer and its Tg is less than or equal to 200°C (Tf - Tg ≤ 200°C).

[0037] In one embodiment, the poly-molecularity index Ip of said thermoplastic polymer is from 2 to 6, in particular from 2 to 3.5, in particular from 2.5 to 3.5.

[0038] The polymolecularity index, noted Ip, is measured by size exclusion or gel permeation chromatography and corresponds to the Mw / Mn ratio.

[0039] The polymolecularity index gives an initial idea of the distribution of the molar masses of the different macromolecules within the polymer. For a perfect polymer, in which all the macromolecules would be linear, would have the same length, and consequently the same molar mass, the polymolecularity index Ip would be equal to 1. For a polyamide obtained by polycondensation from, among other monomers, diamines and dicarboxylic acids, the expected polymolecularity index is 2.0.

[0040] A polydispersity index greater than 2 may be due to the presence of branches or branches on the main polymer chain. In the case of copolyamides, they may appear on the nitrogen atom of the amide function. Thus, they can be quantified by NMR (Nuclear Magnetic Resonance) by comparing the rate of tertiary aromatic amide (branched) to the rate of secondary aromatic amide (linear).

[0041] The presence of connections will impact the viscosity of the resin. The more connections there are, the higher the viscosity will be, leading to poor impregnation.

[0042] It may therefore be necessary to control the branching rate of the thermoplastic polymer used.

[0043] Throughout the description, the term "pre-impregnation or pre-impregnated" is used to designate a fibrous material on which the thermoplastic polymer is deposited before melting of said polymer on the fibrous material and the term "impregnation or impregnated" to designate a fibrous material on which the melting of said thermoplastic polymer has been carried out, in particular by a heating system, or a fibrous material for which the impregnation has been finalized. Thermoplastic polymer matrix

[0044] Said at least one thermoplastic polymer is an amorphous or semi-crystalline polymer whose glass transition temperature is such that Tg ≥ 40°C, in particular Tg ≥ 100°C, in particular ≥ 120°C.

[0045] The number-average molecular weight Mn of said thermoplastic polymer is from 11000 to 25000 g / mol, the melt viscosity of said thermoplastic polymer being from 80 to 1500 Pa.s, as measured by plane-plane rheology under 1 Hz and 2% strain, at a temperature of Tg + 220°C.

[0046] Thermoplastic, or thermoplastic polymer, is understood to mean a material that is generally solid at room temperature, which may be semi-crystalline or amorphous, and which softens upon increasing temperature, in particular after passing its glass transition temperature (Tg) and flows at a higher temperature when it is amorphous, or which may exhibit a frank melting upon passing its so-called melting temperature (Tf) when it is semi-crystalline, and which becomes solid again upon decreasing temperature below its crystallization temperature (for a semi-crystalline material) and below its glass transition temperature (for an amorphous material).

[0047] Tg and Tf are determined by differential scanning calorimetry (DSC) according to standard 11357-2:2013 and 11357-3:2013 respectively.

[0048] Concerning the polymer constituting the impregnation matrix of the fibrous material, it is advantageously a thermoplastic polymer or a mixture of thermoplastic polymers.

[0049] This polymer or mixture of thermoplastic polymers can be ground into powder form, so that it can be used in a device such as a tank, particularly in a fluidized bed or in aqueous dispersion.

[0050] The device in the form of a tank, particularly in a fluidized bed, can be open or closed.

[0051] The thermoplastic polymers used in the constitution of the impregnation matrix of the fibrous material can be chosen from: polymers and copolymers of the family of aliphatic, cycloaliphatic or semi-aromatic polyamides (PA) (also called polyphthalamides (PPA)), polyureas, in particular aromatic, polymers and copolymers of the acrylic family such as polyacrylates, and more particularly polymethyl methacrylate (PMMA) or its derivatives, polymers and copolymers of the family of poly(aryletherketones) (PAEK) such as poly(etheretherketone) (PEEK), or poly(aryletherketoneketones) (PAEKK) such as poly(etherketoneketone) (PEKK) or their derivatives, aromatic polyetherimides (PEI), polyarylsulfides, in particular polyphenylene sulfides (PPS), polyarylsulfones, in particular polyphenylene sulfones (PPSU), polyolefins; polylactic acid (PLA), polyvinyl alcohol (PVA), fluoropolymers, in particular polytetrafluoroethylene (PTFE) or polychlorotrifluoroethylene (PCTFE), and their mixtures.

[0052] Advantageously, the prepolymers constituting the matrix are chosen from Polyamides (PA), in particular chosen from aliphatic polyamides, cycloaliphatic polyamides, and semi-aromatic polyamides (polyphthalamides) optionally modified by urea units, and their copolymers, Polymethyl methacrylate (PPMA) and its copolymers, Polyether imides (PEI), Poly(phenylene sulfide) (PPS), Poly(phenylene sulfone) (PPSU), Poly(etherketoneketone) (PEKK), Poly(etheretherketone) (PEEK).

[0053] For structural parts that have to withstand high temperatures, in addition to fluorinated polymers, PAEK (PolyArylEtherKetone) such as poly(ether ketones) PEK, poly(ether ether ketone) PEEK, poly(ether ketone ketone) PEKK, Poly(ether ketone ether ketone ketone) PEKEKK or PA with a high glass transition temperature Tg are advantageously used according to the invention.

[0054] 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%.

[0055] Advantageously, when said thermoplastic polymer is a mixture, and the pre-impregnation process uses a dry powder, this mixture is in the form of a powder obtained either by "dry blend" before introduction into the pre-impregnation tank or by "dry blend" produced directly in the tank or even by grinding a compound produced beforehand in an extruder.

[0056] In a first variant, the number-average molecular mass Mn of said thermoplastic polymer is from 14,000 to 25,000 and preferably from 15,000 to 21,000 and the melt viscosity of said thermoplastic polymer is from 150 to 1,500 Pa.s and preferably from 200 to 750 Pa.s at a temperature of Tg + 220°C and said thermoplastic polymer is a polymer with a Tg ≥130°C.

[0057] The thermoplastic polymer can therefore be any thermoplastic polymer defined above as long as the Tg ≥130°C.

[0058] Optionally, the thermoplastic polymer or blend of thermoplastic polymers further comprises carbon fillers, in particular carbon black or carbon nanofillers, preferably selected from graphenes, carbon nanotubes, carbon nanofibrils or mixtures thereof. These fillers make it possible to conduct electricity and / or heat, and therefore make it possible to facilitate the melting of the polymer matrix when heated.

[0059] Optionally, said thermoplastic polymer comprises at least one additive, in particular chosen from a catalyst, an antioxidant, a thermal stabilizer, a UV stabilizer, a light stabilizer, a lubricant, a filler, a plasticizer, a flame retardant, a nucleating agent, a chain extender and a colorant, an electrically conductive agent, a thermally conductive agent or a mixture thereof.

[0060] Advantageously, said additive is chosen from a thermal stabilizer, an antioxidant, a flame retardant, an electrically conductive agent and a thermally conductive agent.

[0061] The thermoplastic polymer or blend of thermoplastic polymers may also include liquid crystal polymers or cyclized poly(butylene terephthalate), or blends containing them, such as the CBT100 resin marketed by CYCLICS CORPORATION. These compounds allow in particular to fluidize the polymer matrix in the molten state, for better penetration into the heart of the fibers. Depending on the nature of the polymer, or blend of thermoplastic polymers, used to make the impregnation matrix, in particular its melting temperature, one or the other of these compounds will be chosen.

[0062] Advantageously, said at least one thermoplastic polymer is chosen from polyamides, PEKK, PEI and a mixture of PEKK and PEI.

[0063] Advantageously, when said polymer is a mixture of two polymers P1 and P2, this mixture is composed of a powder obtained by “dry blend”, before introduction into the tank or directly into the tank, and this mixture of two polymers P1 and P2 is a mixture of PEKK and PEI.

[0064] Advantageously, the PEKK / PEI blend is comprised from 90-10% to 60-40% by weight, in particular from 90-10% to 70-30% by weight.

[0065] In this first variant, said thermoplastic polymer can therefore be any thermoplastic polymer as defined above provided that the Tg ≥130°C. Polyamide thermoplastic polymer matrix

[0066] In one embodiment of the first variant defined above, said at least one thermoplastic polymer is a polyamide, in particular thermally stabilized.

[0067] The thermal stabilizer is particularly necessary for polyamides which are likely to degrade at a temperature Tg + 220°C.

[0068] The nomenclature used to define polyamides is described in ISO 1874-1:2011 "Plastics - Polyamide (PA) materials for molding and extrusion - Part 1: Designation", particularly on page 3 (tables 1 and 2) and is well known to those skilled in the art.

[0069] The polyamide may be a homopolyamide or a copolyamide or a mixture thereof. In this first variant where said thermoplastic polymer is a polyamide with a Tg ≥130°C, in particular thermally stabilized, advantageously, said polyamide is a semi-aromatic polyamide.

[0070] For semi-aromatic polyamides, it is optionally modified by urea units, and is in particular a semi-aromatic polyamide of formula X / YAr, as described in EP1505099, in which: Y denotes the residues of an aliphatic diamine having from 8 to 20 carbon atoms, Ar denotes the residues of an aromatic dicarboxylic acid, X denotes either the residues of aminoundecanoic acid NH2-(CH2)10-COOH, lactam 12 or the corresponding amino acid or the Y,x unit remaining from the condensation of the diamine with an aliphatic diacid (x) having between 8 and 20 carbon atoms or the Y,I unit remaining from the condensation of the diamine with isophthalic acid.

[0071] The polyamide X / YAr is in particular a semi-aromatic polyamide of formula A / XT in which A is chosen from a unit obtained from at least one amino acid, a unit obtained from at least one lactam and at least one unit corresponding to the formula (Ca diamine).(Cb diacid), 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, the unit (Ca diamine) being chosen from linear or branched aliphatic diamines, cycloaliphatic diamines and alkylaromatic diamines and the unit (Cb diacid) being chosen from linear or branched aliphatic diacids, cycloaliphatic diacids and aromatic diacids;

[0072] XT denotes a unit obtained from the polycondensation of a Cx diamine and terephthalic acid, with x representing the number of carbon atoms of the Cx diamine, x being between 6 and 36, advantageously between 9 and 18.

[0073] A / MXDT / 10T, one PA MPMDT / 10T, one PA BACT / 10T, one PA BACT / 6T, one PA 11 / BACT, one PA BACT / 10T / 6T, one PA 11 / BACT / 6T, PA 11 / MPMDT / 6T, one PA 11 / BACT / 10T, one PA 11 / MXDT / 10T, one PA 11 / MXDT / 6T.

[0074] It is obvious that for copolyamides of formula A / XT, the proportion of A and XT is a function of the Tg which in this case must be greater than or equal to 130°C.

[0075] T stands for terephthalic acid, MXD stands for m-xylylenediamine, MPMD stands for methylpentamethylenediamine and BAC stands for bis(aminomethyl)cyclohexane which can be either 1,3 BAC or 1,4 BAC.

[0076] Advantageously, said polyamide is a semi-aromatic polyamide chosen from a PA MXDT / 6T, a PA MPMDT / 6T, a PA 11 / BACT, a PA 11 / 6T / 10T, a PA MXDT / 10T, a PA MPMDT / 10T, a PA BACT / 10T, a PA BACT / 6T, PA BACT / 10T / 6T, a PA 11 / BACT / 6T, one PA 11 / MPMDT / 6T, PA 11 / BACT / 10T, one PA 11 / MXDT / 10T, one PA 11 / MXDT / 6T.

[0077] In a second variant, the number-average molecular mass Mn of said thermoplastic polymer is from 11,000 to 20,000 g / mol and preferably 12,000 to 18,000, the melt viscosity of said thermoplastic polymer is from 80 to 650 Pa.s and preferably 100 to 450 Pa.s at a temperature of Tg + 220°C and said thermoplastic polymer is a polyamide of Tg < 130°C.

[0078] In this second variant, the thermoplastic polymer can therefore only be a polyamide with a Tg < 130°C.

[0079] Advantageously, said polyamide is chosen from aliphatic polyamides, cycloaliphatic polyamides and semi-aromatic polyamides with a Tg of less than 130°C, preferably aliphatic polyamides and cycloaliphatic polyamides.

[0080] Aliphatic and cycloaliphatic polyamides consist of repeating units chosen from a unit obtained from the polycondensation of at least one amino acid and a unit obtained from the polycondensation of at least one lactam (for aliphatic polyamides) or a repeating unit XY obtained from the polycondensation: of at least one diamine, said diamine being chosen from a linear (or branched) aliphatic diamine, and a cycloaliphatic diamine of at least one dicarboxylic acid, said diacid being chosen from an aliphatic diacid and a cycloaliphatic diacid, said diamine and said diacid comprising from 4 to 36 carbon atoms, advantageously from 6 to 18 carbon atoms, both for aliphatic polyamides and cycloaliphatic polyamides.

[0081] It is obvious that a cycloaliphatic polyamide comprises at least one cycloaliphatic diamine and / or one cycloaliphatic diacid in the XY unit.

[0082] Advantageously, when said thermoplastic polymer is an aliphatic polyamide, it is chosen from: polyamide 6 (PA-6), polyamide 11 (PA-11), polyamide 12 (PA-12), polyamide 66 (PA-66), polyamide 46 (PA-46), polyamide 610 (PA-610), polyamide 612 (PA-612), polyamide 1010 (PA-1010), polyamide 1012 (PA-1012), polyamide 11 / 1010 and polyamide 12 / 1010, or a mixture thereof or a copolyamide thereof, and block copolymers, in particular polyamide / polyether (PEBA).

[0083] The semi-aromatic polyamides are as defined above from the moment their Tg is less than 130°C, in particular chosen from and the semi-aromatic polyamides are chosen from MXD10, MXD6, PA 6 / 6T, a PA 66 / 6T, a PA 6I / 6T, MPMDT / 10T, 11 / MPMDT / 10T, MPMDT / 6T, a PA BACT / 10T, a PA 11 / BACT / 10T, an MXDT / 10 and a PA 11 / MXDT / 10T. Material fibrous:

[0084] Concerning the fibers constituting said fibrous material, these are in particular continuous fibers of mineral, organic or vegetable origin in the form of strands.

[0085] Advantageously, the number of fibers in said fibrous material for carbon fibers is greater than or equal to 3K, in particular greater than or equal to 6K, in particular greater than or equal to 12K.

[0086] Advantageously, the number of fibers in said fibrous material for carbon fibers is greater than or equal to 12K, in particular chosen from 12K, 24K, 48K, 50K and 400K, in particular 12K, 24K, 48K and 50K.

[0087] Advantageously, the weight for the fiberglass is greater than or equal to 1200 Tex, in particular greater than or equal to 2400 Tex, greater than or equal to 4800 Tex.

[0088] Tex means that 1000 m of base yarn weighs 1 g.

[0089] Among the fibers of mineral origin, mention may be made of carbon fibers, glass fibers, basalt fibers, silica fibers, or silicon carbide fibers for example. Among the fibers of organic origin, mention may be made of fibers based on thermoplastic or thermosetting polymer, such as semi-aromatic polyamide fibers, aramid fibers or polyolefin fibers for example. Preferably, they are based on amorphous thermoplastic polymer and have a glass transition temperature Tg higher than the Tg of the thermoplastic polymer or polymer mixture constituting the impregnation matrix when the latter is amorphous, or higher than the Tf of the thermoplastic polymer or polymer mixture constituting the impregnation matrix when the latter is semi-crystalline.Advantageously, they are based on semi-crystalline thermoplastic polymer and have a melting temperature Tf higher than the Tg of the polymer or mixture of thermoplastic polymer constituting the impregnation matrix when the latter is amorphous, or higher than the Tf of the polymer or mixture of thermoplastic polymer constituting the impregnation matrix when the latter is semi-crystalline. Thus, there is no risk of melting for the organic fibers constituting the fibrous material during impregnation by 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, particularly spider silk, sisal, and other cellulosic fibers, particularly viscose.These plant-based fibers can be used pure, treated or coated with a coating layer, in order to facilitate adhesion and impregnation of the thermoplastic polymer matrix.

[0090] It can also correspond to fibers with holding threads.

[0091] These constituent fibers can be used alone or in mixtures. Thus, organic fibers can be mixed with mineral fibers to be impregnated with thermoplastic polymer and form the impregnated fibrous material.

[0092] Organic fiber strands can have several weights. They can also have several geometries.

[0093] Preferably, the fibrous material consists of continuous carbon, glass, basalt or silicon carbide fibers or a mixture thereof, in particular carbon fibers. It is used in the form of a strand or several strands which then constitute a single strand having the addition of the fibers of each strand.

[0094] The fibers of the fibrous material may or may not be sized.

[0095] The term "sized" refers to the surface treatments applied to fibrous materials during their manufacture. It can also refer to a temporary pretreatment prior to the pre-impregnation stage, whether or not it is carried out directly in line with the impregnation. It can also refer to a temporary pretreatment prior to the pre-impregnation stage, whether or not it is carried out directly in line with the impregnation.

[0096] They are generally organic in nature (thermosetting or thermoplastic resin type) and very often formulated for the pre-impregnation of reinforcing fibers of polymers with a low melting point Tf or thermosetting with a low Tg point.

[0097] These sizes are also useful for protecting dry fibers from damage when in contact with a guidance system.

[0098] In the case of an unsized material, said fibrous material may comprise up to 0.1% by weight of a material of an organic nature (thermosetting or thermoplastic resin type) called sizing.

[0099] In the case of a fleeting pretreatment carried out by the impregnator, for example as a preamble to the pre-impregnation stage of the reinforcing fibers, the size can be an organic liquid such as water, a low or high molecular weight alcohol (ethanol, methanol, isopropanol for example), a ketone (acetone etc.) which will play the role of fleeting size; that is to say it will be present for a short period of time in contact with the fiber to allow its handling in the "dry" state (i.e. before the pre-impregnation) and it will then be extracted from the composite material so as not to disturb the final characteristics of the composite.

[0100] In the case of a sized material, said fibrous material may comprise from 0.1% by weight to 2.5% by weight of a material of an organic nature (thermosetting or thermoplastic resin type) called sizing.

[0101] Advantageously, the fibers of the fibrous material are unsized.

[0102] The term "unsized" means that the fiber is either originally unsized and therefore has not undergone any surface treatment, or that the fiber has been de-sized before use.

[0103] Advantageously, the rate of fibers by volume is constant in at least 70% of the volume of impregnated fibrous material, in particular in at least 80% of the volume of the impregnated fibrous material, in particular in at least 90% of the volume of the impregnated fibrous material, more particularly in at least 95% of the volume of the impregnated fibrous material.

[0104] Advantageously, the distribution of the fibers is homogeneous in at least 95% of the volume of the impregnated fibrous material.

[0105] The measurement of the volume fiber rate is carried out locally on a representative elementary volume (REV).

[0106] The term "constant" means that the fiber content by volume is constant to within the measurement uncertainty of plus or minus 1%.

[0107] The term "homogeneous" means that the impregnation is uniform and that there are no dry fibers, i.e., not impregnated, and that conversely there is no zone of pure resin without fiber in at least 95% of the volume of the impregnated fibrous material ribbon.

[0108] Advantageously, the porosity rate in said impregnated fibrous material is less than 10%, in particular less than 5%, in particular less than 2%.

[0109] It should be noted that a zero porosity rate is difficult to achieve and that consequently, advantageously the porosity rate is greater than 0% but lower than the rates cited above.

[0110] The porosity rate corresponds to the closed porosity rate and is determined as being the relative deviation between the theoretical density and the experimental density of said impregnated fibrous material as described in the examples section of the present invention.

[0111] Advantageously, said impregnated fibrous material is single-layer.

[0112] The term "monolayer" means that when the impregnation of the fibrous material is carried out, the impregnation having been carried out in a particularly homogeneous and core manner, and in particular with at least one expansion during the impregnation, said fibrous material and the polymer are inseparable from each other and form a material consisting of a single layer based on fibers and polymer.

[0113] Advantageously, in the absence of reheating, the impregnated fibrous material is non-flexible.

[0114] This means that the impregnated fibrous material is not capable of conforming to a complex shape at room temperature and can only do so above the Tf of the resin. In other words, the impregnated fibrous material does not exhibit drapability.

[0115] Conversely, when the fibrous material is pre-impregnated, it is flexible and can conform to the shape of the mold, at least in the case of not too complex shapes.

[0116] The different characteristics of number of fibers, fiber rate, sizing, fiber distribution, flexibility and the single-layer characteristic can each be combined or one with one or more others in combination with those of the subject of the invention and can be the subject of as many embodiments as possible combinations which form an integral part of the invention.

[0117] In impregnated materials, also called "ready-to-use", the impregnating polymer or mixture of thermoplastic polymers is distributed uniformly and homogeneously around the fibers. In this type of material, the impregnating thermoplastic polymer must be distributed as homogeneously as possible within the fibers in order to obtain a minimum of porosity, i.e. a minimum of voids between the fibers. Indeed, the presence of porosities in this type of material can act as stress concentration points, during mechanical tensile stress for example, and which then form rupture initiation points of the impregnated fibrous material and weaken it mechanically. A homogeneous distribution of the polymer or mixture of polymers therefore improves the mechanical strength and homogeneity of the composite material formed from these impregnated fibrous materials.

[0118] Thus, in the case of so-called "ready-to-use" impregnated materials, the fiber content in said impregnated fibrous material is from 45 to 65% by volume, preferably from 50 to 60% by volume, in particular from 54 to 60% by volume.

[0119] The measurement of the impregnation rate can be carried out by image analysis (using a microscope or a camera or digital camera, in particular), of a cross-section of the ribbon, by dividing the surface of the ribbon impregnated by the polymer by the total surface of the product (impregnated surface plus surface of the porosity). In order to obtain a good quality image, it is preferable to coat the ribbon cut in its transverse direction in a standard polishing resin and to polish with a standard protocol allowing the observation of the sample under a microscope at a magnification of at least 6 times.

[0120] According to another aspect, the present invention relates to a process for preparing an impregnated fibrous material as defined above, characterized in that it comprises a pre-impregnation step or a step of impregnating said fibrous material with at least one thermoplastic polymer being an amorphous or semi-crystalline polymer whose glass transition temperature is such that Tg ≥ 40°C, in particular Tg ≥ 100°C, in particular ≥ 120°C, the fiber content in said impregnated fibrous material being from 45 to 65% by volume, preferably from 50 to 60% by volume, in particular from 54 to 60% by volume, the number-average molecular weight Mn of said thermoplastic polymer being from 11000 to 25000 g / mol, the melt viscosity of said thermoplastic polymer being from 80 to 1500 Pa.s, as measured in plane-plane rheology under 1 Hz and 2% strain, at a temperature of Tg + 220°C.

[0121] All the characteristics detailed above for the fibrous material and the thermoplastic polymer are also valid for the said process.

[0122] In a first variant of the method, said method comprises a step of impregnating said fibrous material with at least one thermoplastic polymer, the number-average molecular mass Mn of said thermoplastic polymer being between 11,000 and 20,000 g / mol and preferably between 12,000 and 18,000, the melt viscosity of said thermoplastic polymer being between 80 and 650 Pa.s and preferably between 100 and 450 Pa.s at a temperature of Tg + 220°C and said thermoplastic polymer being a polyamide with a Tg < 130°C.

[0123] Advantageously, said polyamide with a Tg < 130°C is chosen from aliphatic polyamides and cycloaliphatic polyamides.

[0124] Advantageously, said aliphatic polyamide is chosen from polyamide 6 (PA-6), polyamide 11 (PA-11), polyamide 12 (PA-12), polyamide 66 (PA-66), polyamide 46 (PA-46), polyamide 610 (PA-610), polyamide 612 (PA-612), polyamide 1010 (PA-1010), polyamide 1012 (PA-1012), polyamide 11 / 1010, polyamide 12 / 1010, or a mixture thereof or a copolyamide thereof, and block copolymers, in particular polyamide / polyether (PEBA) and semi-aromatic polyamides with a Tg <130°C, in particular and the semi-aromatic polyamides are chosen from semi-aromatic polyamides are chosen from MXD10, MXD6, PA 6 / 6T, one PA 66 / 6T, one PA 6I / 6T, MPMDT / 10T, 11 / MPMDT / 10T, MPMDT / 6T, one PA BACT / 10T, one PA 11 / BACT / 10T, one MXDT / 10 and one PA 11 / MXDT / 10T.

[0125] Advantageously, said pre-impregnation is carried out by melting, in particular at high speed, in particular at a speed > 1m / min, preferably > 2m / min and even more preferably > 3m / min.

[0126] Advantageously, in the first variant of the method defined above, said method comprises the following steps: i) impregnation of a fibrous material with at least one non-reactive thermoplastic polymer by melting, in particular by pultrusion, by extrusion at the head of a square of molten polymer, to obtain an impregnated fibrous material, said pre-impregnation step being carried out by at least one thermoplastic polymer, the number-average molecular mass Mn of said thermoplastic polymer being between 11000 and 20000 g / mol and preferably between 12000 and 18000, the viscosity in the molten state of said thermoplastic polymer being between 80 and 650 Pa.s and preferably between 100 and 450 Pa.s at a temperature of Tg + 220°C and said thermoplastic polymer being a polyamide with a Tg < 130°C ii) optionally a step of shaping and calibrating said impregnated fibrous material to obtain an impregnated fibrous material consisting of a ribbon in the form of a thin strip with a thickness 0.2 to 5 mm and preferably 0.2 to 1.3 mm thick.

[0127] In this first variant, the impregnation does not result in a pre-impregnated fibrous material but in an impregnated fibrous material which therefore does not necessarily require a subsequent heating step to finalize the impregnation. However, it would not be outside the invention if a subsequent heating step were carried out after said impregnation step.

[0128] In a second variant, said method comprises a step of pre-impregnation of said fibrous material in the form of a strand or several parallel strands with at least one non-reactive thermoplastic polymer, the number-average molecular mass Mn of said thermoplastic polymer is between 14,000 and 25,000 and preferably between 15,000 and 21,000 and the melt viscosity of said thermoplastic polymer is between 150 and 1,500 Pa.s and preferably between 200 and 750 Pa.s at a temperature of Tg + 220°C and said thermoplastic polymer is a polymer with a Tg ≥130°C.

[0129] Advantageously, said at least one thermoplastic polymer is a polyamide, in particular thermally stabilized.

[0130] Advantageously, said polyamide is chosen from semi-aromatic polyamides.

[0131] In this second variant, said pre-impregnation is carried out with a system chosen from powdering (gravity deposition of a dry powder), spraying by gun, by continuous passage of the fibers in a fluidized bed or an aqueous dispersion of powder of said non-reactive thermoplastic polymer or aqueous dispersion of particles of said thermoplastic polymer or aqueous emulsion or suspension of said non-reactive thermoplastic polymer, in particular at high speed.

[0132] Advantageously, when the pre-impregnation is done by spraying with a gun, a voluntary electrostatic charge process is excluded.

[0133] Advantageously, this second variant comprises at least one heating step without tying up said pre-impregnated fibrous material.

[0134] In this second variant, the said pre-impregnation being carried out by a powder, a dispersion, emulsion or suspension of a powder, it is necessary to dry the powder, in particular deposited by dispersion, emulsion or suspension and / or finalize or begin to finalize the impregnation.

[0135] Advantageously, said second variant comprises at least one heating step carried out by means of at least one anchoring part (E) and at least one heating system, said wick or wicks being in contact with part or all of the surface of said at least one anchoring part (E) and partially or totally passing on the surface of said at least one anchoring part (E) at the level of the heating system.

[0136] This heating step carried out using at least one blocking piece (E) makes it possible to finalize the impregnation which would not be the case after heating without blocking.

[0137] When the pre-impregnation step is carried out by a dispersion, emulsion or suspension of a powder, the heating step without scaling is necessary to dry the pre-impregnated strand(s) and finalize the impregnation. The heating step carried out by means of at least one scaling part (E) is then optional.

[0138] When the pre-impregnation step is carried out by fluidized bed or gun spraying, the heating step without embedding is necessary to start the finalization of the impregnation, i.e. to start the melting of said thermoplastic polymer on said fibrous material. The heating step carried out by means of at least one embedding part (E) is then carried out to finalize the impregnation.

[0139] It is obvious that the two heating stages can be carried out one after the other, that is to say in two separate ovens, or take place in the same oven which then includes both systems.

[0140] Advantageously, the heating system of the heating step without scaling or of the heating step with scaling is chosen from an infrared lamp, a UV lamp, convection heating, microwave heating, laser heating and High Frequency (HF) heating.

[0141] It is obvious that the two heating systems can be the same or different. When the heating system is chosen from an infrared lamp, a UV lamp, and convection heating, then the enclosing part is heated and conducts heat.

[0142] When the heating system is selected from microwave heating, laser heating and High Frequency (HF) heating, then the enclosing part is non-heating and non-conductive of heat.

[0143] Advantageously, a heating grille is excluded from the definition of the heating system with lock.

[0144] Advantageously, in the second variant, when said pre-impregnation is carried out by fluidized bed or spraying by nozzle or gun, in particular by fluidized bed, it is carried out in a tank equipped with at least one stent (E').

[0145] In one embodiment of the second variant described above, said method comprises the following steps: Pre-impregnation of a fibrous material with at least one non-reactive thermoplastic polymer by fluidized bed in a tank, equipped or not with at least one stent (E'), by spraying by nozzle or gun by dry process in a tank, equipped or not with at least one stent (E') to obtain a pre-impregnated fibrous material, said pre-impregnation step being carried out by at least one non-reactive thermoplastic polymer, the number-average molecular mass Mn of said thermoplastic polymer is between 14000 and 25000 and preferably between 15000 and 21000 and the viscosity in the molten state of said thermoplastic polymer is between 150 and 1500 Pa.s and preferably between 200 and 750 Pa.s at a temperature of Tg + 220 °C and said thermoplastic polymer is a polymer of Tg ≥ 130 °C, step of heating without embedding said pre-impregnated fibrous material to obtain a pre-impregnated fibrous material, heating step carried out by means of at least one embedding part (E) and at least one heating system to obtain an impregnated fibrous material, heating step carried out by means of at least one embedding part (E) and at least one heating system to obtain an impregnated fibrous material, optionally step of shaping and calibrating the wick or said parallel wicks of said impregnated fibrous material to obtain an impregnated fibrous material consisting of a ribbon in the form of a thin strip.

[0146] In another embodiment of the second variant described above, said method comprises the following steps: Pre-impregnation of a fibrous material with at least one non-reactive thermoplastic polymer, in particular by continuously passing the fibers through a fluid bed of dry polymer powder, an aqueous dispersion of polymer powder or aqueous dispersion of polymer particles or aqueous emulsion or suspension of polymer, said pre-impregnation step being carried out with at least one amorphous or semi-crystalline thermoplastic polymer and said thermoplastic polymer is a polymer with a Tg ≥130°C, said non-reactive thermoplastic polymer having a number-average molecular weight Mn of said thermoplastic polymer being from 14,000 to 25,000 and preferably from 15,000 to 21,000 and the melt viscosity of said thermoplastic polymer is from 150 to 1,500 Pa.s and preferably from 200 to 750 Pa.s, as measured in plane-plane rheology under 1 Hz and 2% deformation, at a temperature of Tg + 220°C, step of heating without embedding said pre-impregnated fibrous material to obtain a pre-impregnated fibrous material, optionally step of heating carried out by means of at least one embedding part (E) and at least one heating system, as defined above, to obtain an impregnated fibrous material, optionally step of shaping and calibrating the wick or said parallel wicks of said impregnated fibrous material to obtain an impregnated fibrous material consisting of a ribbon in the form of a thin strip.

[0147] Advantageously, the present invention relates to a process for preparing an impregnated fibrous material as defined above, characterized in that one or more skewers (E") are present upstream of said system.

[0148] The expression “upstream of said system” means that the shackle(s) (E") is (are) present before the pre-impregnation stage.

[0149] Advantageously, the present invention relates to a process for preparing an impregnated fibrous material as defined above, characterized in that said process is carried out for the dry powder route at a speed of at least 5 to 30 m / min and for the aqueous dispersion in particular at least 15 m / min. Process for preparing impregnated fibrous material

[0150] The impregnated fibrous material, especially single-layer, can be prepared in two or three steps as described above with an optional shaping and calibration step.

[0151] The first step can be carried out by pre-impregnation of the fibrous material or by impregnation of the fibrous material. First step : pre-impregnation

[0152] The first pre-impregnation step to obtain a pre-impregnated fibrous material can be carried out according to techniques well known to those skilled in the art and in particular chosen from those described above.

[0153] Thus it can be carried out by a pre-impregnation technology by powder deposition, by continuous passage of the fibers in an aqueous dispersion of polymer powder or aqueous dispersion of polymer particles or emulsion or aqueous suspension of polymer, by fluidized bed, equipped or not with at least one stent (E'), by projection by nozzle or gun by dry method in a tank, equipped or not with at least one stent (E'). Fluidized bed :

[0154] The pre-impregnation step can be carried out in a fluidized bed.

[0155] An example of a unit for implementing a manufacturing method without the heating step using at least one enclosing part is described in international application WO 2015 / 121583.

[0156] This system describes the use of a tank comprising a fluidized bed to carry out the pre-impregnation step and can be used within the scope of the invention.

[0157] Another example of a unit for implementing a manufacturing method without the heating step using at least one stent part but with stents present in the tank is described in WO 2018 / 115736.

[0158] Advantageously, the tank comprising the fluidized bed is provided with at least one locking part (E') which may be a compression roller.

[0159] By anchoring part (E') is meant any system on which the wick can move in the tank. The anchoring part (E') can have any shape as long as the wick can move on it.

[0160] It should be noted that the anchoring parts (E) and (E') may be identical or different whether in terms of material or shape and its characteristics (diameter, length, width, height, etc. depending on the shape).

[0161] However, the shoring part (E') is neither heated nor heated.

[0162] The step of pre-impregnation of the fibrous material is carried out by passing one or more strands through a continuous pre-impregnation device, comprising a tank (10) provided with at least one catching part (E') and comprising a fluidized bed (12) of powder of said polymer matrix.

[0163] The powder of said polymer or polymer matrix is suspended in a gas G (air for example) introduced into the tank and circulating in the tank (10) through a hopper (11). The wick(s) are circulated in this fluidized bed (12).

[0164] The tank may have any shape, in particular cylindrical or parallelepiped, in particular a rectangular parallelepiped or a cube, advantageously a rectangular parallelepiped.

[0165] The tank (10) can be an open or closed tank.

[0166] In the case where the tank is closed, it is then equipped with a sealing system so that the powder of said polymer matrix cannot escape from said tank.

[0167] This pre-impregnation step is therefore carried out by a dry process, that is to say that the thermoplastic polymer matrix is in powder form, in particular suspended in a gas, in particular air, but cannot be dispersed in a solvent or in water. Each strand to be pre-impregnated is unwound from a reel device under the traction generated by cylinders (not shown).

[0168] Each reel is equipped with a brake (not shown) to apply tension to each fiber strand. In this case, an alignment module allows the fiber strands to be arranged parallel to each other. In this way, the fiber strands cannot come into contact with each other, which prevents mechanical damage to the fibers caused by friction between them.

[0169] The strand of fibers or the strands of parallel fibers then pass into a tank (10), comprising in particular a fluidized bed (12), provided with a locking part (E') which is a compression roller (24). The strand of fibers or the strands of parallel fibers then exit(s) the tank after pre-impregnation after possible control of the residence time in the powder.

[0170] The term "powder residence time" means the time during which the wick is in contact with said powder in the fluidized bed.

[0171] If the fibrous material, such as glass, basalt or carbon fiber rovings, has a size, an optional de-size step can be carried out before the fibrous material enters the tank.

[0172] Advantageously, the tank used comprises a fluidized bed with a wick and said pre-impregnation step is carried out with simultaneous expansion of said wick or wicks between the inlet and the outlet of the tank comprising said fluidized bed.

[0173] The term "tank inlet" refers to the vertical tangent of the edge of the tank that includes the fluidized bed.

[0174] The term "tank outlet" corresponds to the vertical tangent of the other edge of the tank which includes the fluidized bed.

[0175] Spreading consists of distinguishing each fiber constituting the said wick as much as possible from the other fibers which surround it in its closest space. It corresponds to the transverse spreading of the wick.

[0176] In other words, the transverse spread or width of the wick increases between the inlet of the tank comprising the fluidized bed and the outlet of the tank comprising the fluidized bed and thus allows improved pre-impregnation of the fibrous material.

[0177] The use of at least one skewer (E'), in particular a cylindrical compression roller, in the pre-impregnation step therefore allows improved pre-impregnation compared to the methods of the prior art.

[0178] The expression "compression roller" means that the rolling wick rests partially or totally on the surface of said compression roller, which causes said wick to expand.

[0179] Advantageously, said at least one compression roller is cylindrical in shape and the percentage of expansion of said wick or wicks between the inlet and the outlet of the tank of said fluidized bed is between 1% and 1000%, preferably between 100% and 800%, preferably between 200% and 800%, preferably between 400% and 800%.

[0180] The bloom percentage is equal to the ratio of the final width of the wick to the initial width of the wick multiplied by 100.

[0181] 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.

[0182] Below 3 mm, the deformation of the fiber induced by the compression roller is too great.

[0183] Advantageously, the compression roller is cylindrical and not grooved and in particular is metallic.

[0184] When the tying part (E') is at least one compression roller, according to a first variant, a single compression roller is present in the fluidized bed and said pre-impregnation is carried out at the angle α 1 formed by said wick or wicks between the inlet of said compression roller and the vertical tangent to said compression roller.

[0185] The angle α 1 formed by said wick or wicks between the entrance of said compression roller and the vertical tangent to said compression roller allows the formation of a zone in which the powder will concentrate, thus leading to a “wedge effect” which, with the simultaneous expansion of the wick by said compression roller, allows pre-impregnation over a greater width of wick and therefore improved pre-impregnation compared to the techniques of the improved prior art.

[0186] Throughout the description, all angle values given are expressed as absolute values.

[0187] Advantageously, the angle α 1 is between 0 and 89°, preferably between 5° and 85°, preferably between 5° and 45°, preferably between 5° and 30°.

[0188] However, an angle α 1 between 0 and 5° is likely to generate risks of mechanical stress, which will lead to breakage of the fibers and an angle α 1 between 85° and 89° does not create sufficient mechanical stress to create the “wedge effect”.

[0189] A value of the angle α 1 equal to 0° therefore corresponds to a vertical fiber. It is obvious that the height of the cylindrical compression roller is adjustable, thus allowing the fiber to be positioned vertically.

[0190] Advantageously, the inlet edge of the tank (23a) is equipped with a roller, in particular cylindrical and rotating, on which said wick or wicks pass, thus leading to a development prior to pre-impregnation.

[0191] It is obvious that the "wedge effect" caused by the angle α 1 promotes pre-impregnation on one face but the expansion of said wick obtained by means of the compression roller also allows for pre-impregnation on the other face of said wick. In other words, said pre-impregnation is promoted on one face of said wick or wicks at the angle α 1 formed by said wick or wicks between the entry of said at least one compression roller R 1 and the vertical tangent to the compression roller R 1 but the expansion also allows for pre-impregnation of the other face.

[0192] The angle α 1 is as defined above.

[0193] Advantageously, the volume diameter D90 of the thermoplastic polymer powder particles is between 30 and 500 µm, advantageously between 80 and 300 µm.

[0194] Advantageously, the volume diameter D10 of the thermoplastic polymer powder particles is from 5 to 200 µm, advantageously from 15 to 100 µm.

[0195] Advantageously, the volume diameter of the thermoplastic polymer powder particles is within the ratio D90 / D10, i.e. from 1.5 to 50, advantageously from 2 to 10.

[0196] Advantageously, the average diameter D50 by volume of the thermoplastic polymer powder particles is from 10 to 300 µm, in particular from 30 to 200 µm, more particularly from 45 to 200 µm.

[0197] The volume diameters of the particles (D10, D50 and D90) are defined according to the ISO 9276:2014 standard.

[0198] The “D50” corresponds to the volume average diameter, that is to say the value of the particle size which divides the population of particles examined exactly in two.

[0199] The “D90” corresponds to the 90% value of the cumulative curve of the particle size distribution in volume.

[0200] The “D10” corresponds to the size of 10% of the particle volume.

[0201] According to other variants, two, three or more rollers may be present in the fluidized bed. Spray gun :

[0202] Another example of a unit for implementing a manufacturing method without the heating step using at least one stent part but with stents present in the tank is described in WO 2018 / 115737.

[0203] The step of pre-impregnating the fibrous material can also be carried out by passing one or more strands through a continuous pre-impregnation device by projection, comprising a tank, comprising one or more nozzles or one or more guns projecting the polymer powder onto the fibrous material at the roller inlet.

[0204] The polymer(s) or polymer powder is projected into the tank by means of nozzle(s) or gun(s) at the level of the shoring part, in particular the compression roller (at the inlet) on said fibrous material. The wick(s) are put into circulation in this tank.

[0205] All the characteristics of the swages, and in particular the compression rollers, the spreading, and the angle α 1 causing the wedge effect and detailed for the fluidized bed are also valid for spraying by gun.

[0206] According to other variants, two, three or more rollers may be present, each equipped with a gun. First step: impregnation

[0207] The first impregnation step to obtain an impregnated fibrous material can be carried out according to techniques well known to those skilled in the art and in particular chosen from those described above.

[0208] It can therefore be carried out by melting, in particular by pultrusion, by extrusion of molten polymer at the right angle,

[0209] The impregnation step is carried out in particular by extrusion of the polymer matrix at the square head and passage of said wick or wicks into this square head then passage into a heated die, the square head possibly being provided with fixed or rotating clamps on which the wick passes thus causing a spreading of said wick allowing a pre-impregnation of said wick.

[0210] The impregnation can in particular be carried out as described in US 2014 / 0005331A1 with the difference that the resin supply is carried out on both sides of said wick and that there is no contact surface eliminating part of the resin on one of the two surfaces.

[0211] Advantageously, the impregnation step is carried out by high-speed melting, i.e. with a running speed of said wick or wicks, in particular at a speed of at least 1 to 10 m / min for the melting, in particular at least 2 m / min. Second step : heating without scaling and drying of the pre-impregnated fibrous material

[0212] As already indicated above, this heating step without embedding allows the pre-impregnated wick to be dried, in particular by dispersion, suspension or emulsion, and to begin or finalize the impregnation depending on the length of the oven containing the heating system.

[0213] The heating system allows the melting of said thermoplastic polymer impregnating said fibrous material.

[0214] Said heating system is in particular an IR, high frequency microwave or laser, in particular IR with a power of between 0.1W and 10kW, more preferably between 0.1 and 6kW, more preferably between 0.1 and 3kW, even more preferably between 0.6 and 3kW, even more preferably between 0.6 and 1.8kW.

[0215] Third optional step: heating with embedding of the pre-impregnated fibrous material and finalization of the impregnation.

[0216] The pre-impregnation step can therefore be carried out by any means equipped or not with at least one shim (E').

[0217] The presence of the shim allows the wick to expand and promotes pre-impregnation. However, the presence of this shim is not essential as long as a heating system equipped with at least one shim (E) is present after the pre-impregnation stage to finalize the impregnation.

[0218] The term "clamping part (E)" means any system on which the bit can move. The clamping part (E) can have any shape as long as the bit can move on it. It can be fixed or rotating.

[0219] The heating system is any system releasing heat or emitting radiation capable of heating the enclosing part (E).

[0220] It can be chosen from infrared lamp, UV lamp, convection heater, microwave heater, laser heater and High Frequency (HF) heater.

[0221] The heating system allows the melting of said thermoplastic polymer impregnating said fibrous material.

[0222] Said heating system is in particular an IR, high frequency microwave or laser, in particular IR with a power of between 0.1W and 10kW, more preferably between 0.1 and 6kW, more preferably between 0.1 and 3kW, even more preferably between 0.6 and 3kW, even more preferably between 0.6 and 1.8kW.

[0223] The enclosing part (E) is therefore conductive or absorbs the radiation emitted by the heat.

[0224] The term "heat-conducting enclosing part (E)" means that the enclosing part (E) is made of a material capable of absorbing and conducting heat. It can also be a high-frequency, microwave or laser heating system.

[0225] In this case, the enclosing part is not a heat conductor or does not absorb the radiation emitted by the heat.

[0226] The term "non-heat-conducting enclosing part (E)" means that the enclosing part (E) is made of a material incapable of absorbing and conducting heat. Said at least one enclosing part (E) is located or included in the environment of the heating system, i.e. it is not outside the heating system.

[0227] Advantageously, said heating system surmounts said at least one enclosing part (E). The heating system is at a sufficient height so that the polymer present on the wick can melt but without degrading said polymer.

[0228] However, said heating system comprises either only said at least one snubbing part (E) but may also comprise a portion of the wick, outside of said snubbing system (E), said portion of wick being located before and / or after said snubbing system (E).

[0229] The height between the heating system and the jambs is between 1 and 100 cm, preferably between 2 and 30 cm, in particular between 2 and 10 cm.

[0230] It would not be outside the scope of the invention if the shoring piece (E) were positioned in an oven comprising a heating system, for example by IR, but said shoring piece were not positioned exactly under the heating elements, for example by IR. It would not be outside the scope of the invention if the oven comprised a convection heating mode and an IR heating system.

[0231] It would also not be outside the scope of the invention if said shoring piece (E) placed in this furnace or in the environment of this furnace, were equipped with an autonomous heating means such as a resistor making it possible to heat said shoring piece (E), independently for example of the radiation of the IR lamps and the natural convection of the furnace and that, taking into account the speed of the line, the polymer present in the ribbons or wicks is still in the molten state when it comes into contact with said shoring piece. The height between the heating system and the shorings is between 1 and 100 cm, preferably between 2 and 30 cm, in particular between 2 and 10 cm.

[0232] It is obvious that a second heating system can be present under the wicks, thus allowing uniform fusion of said polymer on both surfaces of the wick.

[0233] The heating system may be a horizontal system. However, the heating system(s) may be arranged vertically with the wick also passing vertically through the shackles.

[0234] Therefore, this heating step makes it possible to perfect the impregnation of the wick carried out previously during the pre-impregnation step and in particular to obtain a homogeneous and core impregnation.

[0235] Indeed, whatever the system used for the pre-impregnation step, a first blooming occurs during this step, in particular if the pre-impregnation step is carried out using staking parts (E'), such as in a fluidized bed with at least one staking as described above.

[0236] A first expansion of the wick occurs at the level of said compression rollers corresponding to the anchoring parts (E') with "wedge effect" due to the partial or total scrolling of said wick on said anchoring part(s) (E') and a second expansion occurs during the heating step, at the level of said compression rollers corresponding to the anchoring parts (E) due to the partial or total scrolling of said wick on said anchoring part(s) (E).

[0237] The heating system can be separated into two and therefore consist of two heating systems, a first heating system before said scaling parts (E) and a second heating system comprising said scaling parts. It is obvious that the distance between the two heating systems is then sufficient for the polymer to remain in the molten state.

[0238] The two heating systems can be of the same or different nature and of the same or different power.

[0239] This second expansion is preceded during the passage of the wick in the heating system, before its partial or total scrolling on the said locking part(s) (E), by a retraction of the wick due to the melting of the polymer on the said wick.

[0240] This second expansion combined with the melting of said polymer matrix by the heating system and the shrinkage of the wick make it possible to homogenize the pre-impregnation and thus finalize the impregnation and thus have a core impregnation and have a high rate of fibers in volume, in particular constant in at least 70% of the volume of the ribbon, in particular in at least 80% of the volume of the ribbon, in particular in at least 90% of the volume of the ribbon, more particularly in at least 95% of the volume of the ribbon, as well as to reduce the porosity.

[0241] Advantageously, the percentage of expansion during the heating step between the entry of the first compression roller R' 1 and the exit of the last compression roller R' i is approximately 0 to 300%, in particular 0 to 50%.

[0242] The various expansions during the heating step combined with the melting of the thermoplastic polymer and the shrinking of the wick during said heating step make it possible to obtain a rate of impregnated fibers after the heating step of 45 to 65% by volume, preferably 50 to 60% by volume, in particular 54 to 60% (a rate of fibers which cannot be achieved by conventional melt-process techniques), the rate of fibers by volume and the distribution of the fibers being substantially identical on average on either side of the median plane of the fibrous material over the entire length of said fibrous material, thus leading to the production of a fibrous material, in particular a single-layer.

[0243] Below 45% fibers, the reinforcement is of no interest in terms of mechanical properties.

[0244] Above 65%, the process limits are reached and the mechanical properties are lost.

[0245] Advantageously, the porosity rate in said impregnated fibrous material is less than 10%, in particular less than 5%, in particular less than 2%. Shaping and calibration step : obtaining the thin band

[0246] A step of shaping the wick or said parallel wicks and calibrating said impregnated fibrous material can be carried out after leaving the second heating system.

[0247] This step can be carried out directly after exiting the second heating system and in this case the speed of movement of the wick is identical in the second and third heating systems or in a delayed manner, which means that the speed of movement of the wick can be different between the second and third heating systems.

[0248] This step can be carried out in one of the following ways: 1) passing a strip after impregnation over one or more strips (as defined for (E)) of which at least one strip is notched (grooved), the average width of said strip being less than the notched (or grooved) strip.

[0249] At least one of said shims is located under a third heating system, in particular IR, microwave or high frequencies or laser, in particular IR with power (for each ribbon or stack of parallel ribbons) between 0.1W and 10kW, more preferably between 0.1 and 6kW, more preferably between 0.1 and 3kW, even more preferably between 0.6 and 3kW, even more preferably between 0.6 and 1.8kW. Advantageously, said at least one notched roller (41) is located first and is outside the third heating system (45). Advantageously, a second notched shim (44) is present at the outlet and outside the third heating system.

[0250] The passage over the non-notched bars (42) and (43) allows the strip to be re-spread to the width of the notched bar.

[0251] The diameter of the notched locking device(s) (41) and (44) is between 12 mm and 50 mm, in particular between 12 mm and 30 mm.

[0252] The diameter of the non-notched locking device(s) (42) and (43) is between 10 mm and 50 mm, in particular between 10 mm and 30 mm.

[0253] After passing under the third heating system, the strip shaped to the width of the notched bar at the outlet of the third heating system passes to the level of heating calenders (46) mounted in series equipped with an IR of 1kW each and whose delivered power is adjustable, outside the third heating system, to obtain the calibrated strip.

[0254] 2) passage of a strip over one or more shims (as defined for (E)) of which at least one shim is notched (grooved), the average width of said strip being greater than the notched (or grooved) shim.

[0255] Said embargoes are located under a third heating system, in particular IR, high frequency microwave or laser, in particular IR with power (for each ribbon or stack of parallel ribbons) between 0.1W and 10kW, more preferably between 0.1 and 6kW, more preferably between 0.1 and 3kW, even more preferably between 0.6 and 3kW, even more preferably between 0.6 and 1.8kW.

[0256] Advantageously, said at least one notched roller is located first.

[0257] The passage over the first notched interlock allows the width of the strip to be reduced below the width of the notched groove. Advantageously, a second notched interlock is present at the outlet and outside the third heating system with a groove of width greater than the width of the strip.

[0258] After passing under the third heating system, the strip shaped to the width of the notched bar at the outlet and outside the third heating system passes to the level of heating calenders mounted in series equipped with a 1kW IR, outside the third heating system, to obtain the calibrated strip.

[0259] A calendering system with pressure and roller spacing management as described in WO 2015 / 121583 can be used in both of these embodiments.

[0260] The swaging is in particular a fixed or rotating, or even counter-rotating, notched roller, in particular fixed to gather said impregnated fibrous material to the correct width.

[0261] The notched roller can also have rounded edges at the lateral contacts with the snare to avoid damaging the fibers at the edge of the thin strip.

[0262] The term "rounded edges" means that the bottom of the notch is concave or convex in shape.

[0263] Advantageously, the first embodiment of the shaping and calibration step is preferred.

[0264] This therefore makes it possible to work with high scrolling speeds and thus reduce production costs.

[0265] According to another aspect, the present invention relates to the use of an impregnated fibrous material, as defined above, for the preparation of ribbons suitable for the manufacture of three-dimensional composite parts, by automatic deposition of said ribbons by means of a robot.

[0266] All the characteristics detailed above for the fibrous material are also valid for the said use.

[0267] According to another aspect, the present invention relates to the use of an impregnated fibrous material, as defined above, for the preparation of thermoformable sheets.

[0268] All the characteristics detailed above for the fibrous material are also valid for the said use.

[0269] Advantageously, the impregnated fibrous material used above is pre-cut into pieces, said pieces being randomly associated or oriented for the preparation of the thermoformable sheet.

[0270] Thermoforming is carried out beyond the Tg for an amorphous thermoplastic polymer or between the Tg and the Tf for a semi-crystalline thermoplastic polymer but it can also be carried out beyond the Tf of the thermoplastic polymer for a semi-crystalline one.

[0271] The impregnated fibrous material is pre-cut into pieces having a width equal to the initial width of said fibrous material and a length of 5 to 50 mm, in particular 20 to 30 mm, said pieces being randomly associated or oriented for the preparation of the thermoformable sheet.

[0272] According to another aspect, the present invention relates to the use of at least one non-reactive thermoplastic polymer, said at least one non-reactive thermoplastic polymer being an amorphous or semi-crystalline thermoplastic polymer whose glass transition temperature is such that Tg ≥ 40°C, in particular Tg ≥ 100°C, in particular ≥ 120°C, said thermoplastic polymer having the number-average molecular weight Mn of said thermoplastic polymer being from 11000 to 25000 g / mol, the melt viscosity of said thermoplastic polymer being from 80 to 1500 Pa.s, as measured by plane-plane rheology under 1 Hz and 2% strain, at a temperature of Tg + 220°C, as defined above, for impregnating a fibrous material.

[0273] All the characteristics detailed above for the fibrous material are also valid for the said use. Advantageous embodiments of the method of the invention

[0274] Advantageously, the fibrous material is chosen from carbon fiber strands in particular greater than or equal to 12K, in particular chosen from 12K, 24K, 48K, 50K and 400K, in particular 12K, 24K, 48K and 50K, and glass fibers in particular whose grammage is greater than or equal to 1200 Tex, in particular greater than or equal to 2400 Tex, greater than or equal to 4800 Tex.

[0275] Advantageously, the thermoplastic prepolymer used to impregnate the carbon fiber is chosen from a polyamide, in particular an aliphatic polyamide such as PA 11, PA 12, a PA 11 / 1010 and a PA 12 / 1010, a semi-aromatic polyamide, in particular a PA MPMDT / 6T, a PA PA11 / 10T, a PA 11 / BACT, a PA 11 / 6T / 10T, a PA MXDT / 10T, a PA MPMDT / 10T, a PA BACT / 10T, a PA BACT / 6T, PA BACT / 10T / 6T, a PA 11 / BACT / 6T, PA 11 / MPMDT / 10T, PA 11 / BACT / 10T, a PA 11 / MXDT / 10T, a PEKK, a PEEK and a PEI or a mixture thereof.

[0276] Advantageously, the thermoplastic prepolymer used to impregnate the glass fiber is chosen from a polyamide, in particular an aliphatic polyamide such as PA 11, PA 12, a PA 11 / 1010 and a PA 12 / 1010, a semi-aromatic polyamide, in particular a PA MPMDT / 6T, a PA PA11 / 10T, a PA 11 / BACT, a PA 11 / 6T / 10T, a PA MXDT / 10T, a PA MPMDT / 10T, a PA BACT / 10T, a PA BACT / 6T, PA BACT / 10T / 6T, a PA 11 / BACT / 6T, PA 11 / MPMDT / 10T, PA 11 / BACT / 10T, a PA 11 / MXDT / 10T, a PEKK, a PEEK and a PEI or a mixture thereof.

[0277] Advantageously, the fibrous material comprises carbon fiber strands greater than or equal to 12K, in particular chosen from 12K, 24K, 48K, 50K and 400K, in particular 12K, 24K, 48K and 50K, and the thermoplastic polymer used to pre-impregnate the carbon fiber is chosen from a polyamide, in particular an aliphatic polyamide such as PA 11, PA 12, a PA 11 / 1010 and a PA 12 / 1010, a semi-aromatic polyamide, in particular a PA MPMDT / 6T, a PA PA11 / 10T, a PA 11 / BACT, a PA 11 / 6T / 10T, a PA MXDT / 10T, a PA MPMDT / 10T, a PA BACT / 10T, a PA BACT / 6T, PA BACT / 10T / 6T, a PA 11 / BACT / 6T, PA 11 / MPMDT / 10T, PA 11 / BACT / 10T, a PA 11 / MXDT / 10T, a PEKK, a PEEK and a PEI or a mixture of these.

[0278] Advantageously, the fibrous material consists of carbon fiber strands greater than or equal to 12K, in particular chosen from 12K, 24K, 48K, 50K and 400K, in particular 12K, 24K, 48K and 50K, and the thermoplastic polymer used to pre-impregnate the carbon fiber is chosen from a polyamide, in particular an aliphatic polyamide such as PA 11, PA 12, a PA 11 / 1010 and a PA 12 / 1010, a semi-aromatic polyamide, in particular a PA MPMDT / 6T, a PA PA11 / 10T, a PA 11 / BACT, a PA 11 / 6T / 10T, a PA MXDT / 10T, a PA MPMDT / 10T, a PA BACT / 10T, a PA BACT / 6T, PA BACT / 10T / 6T, a PA 11 / BACT / 6T, PA 11 / MPMDT / 10T, PA 11 / BACT / 10T, a PA 11 / MXDT / 10T, a PEKK, a PEEK and a PEI or a mixture of these.

[0279] Advantageously, the fibrous material comprises fiberglass strands whose grammage is greater than or equal to 1200 Tex, in particular greater than or equal to 2400 Tex, greater than or equal to 4800 Tex and the thermoplastic polymer used to pre-impregnate the fiberglass is chosen from a polyamide, in particular an aliphatic polyamide such as PA 11, PA 12, a PA 11 / 1010 and a PA 12 / 1010, a semi-aromatic polyamide, in particular a PA MPMDT / 6T, a PA PA11 / 10T, a PA 11 / BACT, a PA 11 / 6T / 10T, a PA MXDT / 10T, a PA MPMDT / 10T, a PA BACT / 10T, a PA BACT / 6T, PA BACT / 10T / 6T, a PA 11 / BACT / 6T, PA 11 / MPMDT / 10T, PA 11 / BACT / 10T, a PA 11 / MXDT / 10T, a PEKK, a PEEK and a PEI or a mixture of these.

[0280] Advantageously, the fibrous material consists of fiberglass strands whose grammage is greater than or equal to 1200 Tex, in particular greater than or equal to 2400 Tex, greater than or equal to 4800 Tex and the thermoplastic polymer used to pre-impregnate the fiberglass is chosen from a polyamide, in particular an aliphatic polyamide such as PA 11, PA 12, a PA 11 / 1010 and a PA 12 / 1010, a semi-aromatic polyamide, in particular a PA MPMDT / 6T, a PA PA11 / 10T, a PA 11 / BACT, a PA 11 / 6T / 10T, a PA MXDT / 10T, a PA MPMDT / 10T, a PA BACT / 10T, a PA BACT / 6T, PA BACT / 10T / 6T, a PA 11 / BACT / 6T, PA 11 / MPMDT / 10T, PA 11 / BACT / 10T, a PA 11 / MXDT / 10T, a PEKK, a PEEK and a PEI or a mixture of these. Brief description of the figures

[0281] [ Fig. 1] presents the morphology of a microcracked but perfectly impregnated composite plate obtained from a 11 / 10T / 6T polymer with a too low molecular mass Mn=10500g / mol, with a melt viscosity (plane-plane rheology under 1 Hz and 2% deformation) of 70 Pa.s at 330°C. The scale bar represents 50µm. [ Fig. 2 ] presents the morphology of the same microcracked composite plate as the Figure 1 but at a higher magnification. The scale bar represents 20µm. [ Fig. 3 ] presents the morphology of a composite plate with dry fiber zones obtained from an 11 / 10T / 6T polymer with a high molecular mass Mn=27200g / mol and a melt viscosity (plane-plane rheology under 1 Hz and 2% deformation) of 1790 Pa.s at 330°C. The scale bar represents 100µm. [ Fig. 4 ] presents the morphology of the same composite plate with dry zones as the Figure 3but at a higher magnification. The scale bar represents 20µm. [ Fig. 5 ] shows the morphology of a composite plate with no micro cracks or dry zones obtained from a 11 / 10T / 6T polymer with a mass Mn=13700g / mol, with a melt viscosity (plane-plane rheology, under 1 Hz and 2% deformation at Tg + 220°C) of 185 Pa.s at 330°C, attesting that the molecular mass of the polymer is optimal. The scale bar represents 200µm. [ Fig. 6 ] presents the morphology of the same composite plate with no micro cracks or dry zones as the Figure 5 but at a higher magnification. The scale bar represents 20µm. Examples

[0282] The following examples illustrate in a non-limiting manner the scope of the invention. Example 1 (comparative example):

[0283] Impregnation of a fibrous material with a PA of type 11 / 10T / 6T, Tg 110°C, mass Mn=10500g / mol, melt viscosity (plane-plane rheology under 1 Hz and 2% deformation) of 70 Pa.s at 330°C.

[0284] This polymer is ground into a powder with an average diameter of D50=110µm and then the powder is deposited by gravity on the surface of a 3B Advantex SE4535 glass fiber reinforcement, woven in the form of a 400g / m 2< UDT (UD tape): this type of reinforcement is a quasi-UD (unidirectional fibers) since 90% of the fibers are in the weft direction.

[0285] The whole thing is heated by infrared to fix the powder.

[0286] The powder rate is 30% by weight (or 50% by volume).

[0287] The prepreg thus obtained is cut into 300*200mm formats and 4 of these formats are superimposed to form a preform which will then be consolidated under a CARVER press at 330°C for 15 minutes then cooled and demolded at 100°C.

[0288] Bending specimens are taken in the minority direction of the fibers (90° orientation) tested according to standard 14125(1998).

[0289] The results are given in Table I below. The breaking stress value of 40 MPa in bending obtained with the mass of 10500 is considered insufficient to protect against the presence of premature micro-cracking of the composite at the fiber & resin interface, during mechanical or thermal loading.

[0290] This result is obtained despite perfect impregnation of the fibers but we can see the presence of microcracks in the plates (see Figure 1 ), which appear during cooling under the effect of thermal stresses and affect the resistance of the composite obtained: in this case, it is concluded that the polymer used has an insufficient molecular mass. Example #2 (comparative example):

[0291] Impregnation of a fibrous material with a PA of type 11 / 10T / 6T, Tg 110°C, mass Mn=27200g / mol, melt viscosity (plane-plane rheology under 1 Hz and 2% deformation) of 1790 Pa.s at 330°C according to example 1.

[0292] The nature of the fiber reinforcement, the manufacturing process of the pre-impregnated material, the composite plate and the mechanical test protocol are identical to those of example 1.

[0293] The result obtained, in transverse bending (90°) according to ISO 14125(1998), is presented in Table I: it is close to that obtained with the low mass polymer of example no. 1: this time this attests that the mass of the polymer is too high and prevents good impregnation of the fibers, which is observed (cf. Figure 2 ) by the presence of dry areas devoid of resin in the consolidated plate.

[0294] The polymer being too high in Mn, it is therefore too viscous and its impregnation therefore leads to dry areas. Example 3:

[0295] Impregnation of a fibrous material with a PA of type 11 / 10T / 6T, Tg 110°C, mass Mn=13700g / mol, melt viscosity (plane-plane rheology, under 1 Hz and 2% deformation at Tg + 220°C) is 185 Pa.s at 330°C.

[0296] The nature of the fiber reinforcement, the manufacturing process of the pre-impregnated material, the composite plate and the mechanical test protocol are identical to those of example 1.

[0297] A clear improvement in transverse mechanical properties (90°) according to ISO 14125(1998) is seen when the molecular weight of the resin increases from 10500 to 13700.

[0298] The morphology of the plates (cf. Figure 3 ) shows that unlike comparative examples no. 1 and 2, no micro cracks or dry zones are present in the plate, attesting that the molecular mass of the polymer is optimal. Example #4

[0299] Impregnation of a fibrous material with a PA of the MPMDT / 10T type (67 / 33 mol%) of D50 = 115µm with a Tg of 125°C. Its mass is 14000 g / mol (measured by NMR) and its melt viscosity (plane-plane rheology, under 1 Hz and 2% deformation at Tg + 220°C) is 214 Pa.s at 345°C.

[0300] This polymer is ground into a powder with an average diameter D50=115 µm. The powder is added in a dry blend with a thermal stabilizing agent, then deposited according to example 1 on the surface of an Advantex glass fiber reinforcement from 3B, SE4535 woven in the form of a UDT (90% of the fibers are in the weft direction and 10% in the warp direction) of 400g / m2. The powder content is 30% by weight (i.e. 50% by volume).

[0301] The pre-impregnated material thus obtained is cut into 300*200mm formats and 4 of these formats are superimposed to form a preform which will then be consolidated under a CARVER press at 345°C for 15 minutes then cooled and demolded at 100°C.

[0302] Bending specimens are taken in the majority direction of the fibers (weft direction), tested according to ISO 14125(1998) standard.

[0303] The results are given in Table I below.

[0304] We note that the molecular mass / melt viscosity compromise is satisfactory. Example 5:

[0305] Impregnation of a fibrous material with a BACT / 10T type PA with a Tg of 140°C. Its mass is 19100 g / mol (measured by NMR) and its melt viscosity (plane-plane rheology, under 1 Hz and 2% deformation at Tg + 220°C) is 502 Pa.s at 360°C.

[0306] This polymer is ground into a powder with an average diameter of DN50=110 µm. The powder is added in a dry blend with a thermal stabilizing agent, then deposited according to example 1 on the surface of an Advantex fiberglass reinforcement from 3B, SE4535 woven in the form of a UDT (90% of the fibers are in the weft direction and 10% in the warp direction) of 400g / m 2< . The powder content is 30% by weight (i.e. 50% by volume).

[0307] The pre-impregnated material thus obtained is cut into 300*200mm formats and 4 of these formats are superimposed to form a preform which will then be consolidated under a CARVER press at 360°C for 15 minutes then cooled and demolded at 100°C.

[0308] Bending specimens are taken in the majority direction of the fibers (weft direction), tested according to ISO 14125(1998) standard.

[0309] The results are given in Table I below.

[0310] We note that the molecular mass / melt viscosity compromise is satisfactory. Example 6:

[0311] The polymer is an MXD10 with a mass of 15,000 g / mol. Its Tg is 70°C, its viscosity at 290°C is 110 Pa.s

[0312] The composite sheet manufacturing process is a pultrusion process with melt impregnation using a die at the crosshead. The polymer is introduced in the form of granules, previously compounded with a thermally stabilizing agent, into an extruder that feeds the crosshead.

[0313] The temperature at which the fibers were impregnated was 290°C.

[0314] The line speed was 1.1 m / min pb / claimed speed range

[0315] The fiber used is 3B SE4535 Hypertex glass fiber

[0316] The fiber rate was 60% by volume.

[0317] Excellent mechanical properties are obtained, measured in bending according to the ISO 14125 (1998) standard. They are summarized in Table I below: In this example, unlike the other examples, no rupture is observed in transverse bending, up to 10% deformation, value beyond which the test is interrupted because it then goes outside the conditions recommended by the ISO 14125 standard. In this case, the excellence of the transverse mechanical properties is judged by the ductility of the composite obtained (i.e. the value of the deformation reached perpendicular to the fibers (90° direction)), which attests to a good compromise between melt viscosity and molecular mass. [Table 1] Example No. Mn Tg (°C) Melt viscosity (Pa.s) at Tg +220°C Modulus 90° (GPa) Stress 90° (MPa) 1 10500 110 70 7,7 41 2 27200 110 1790 3,6 46 3 13700 110 185 10,2 79 4 14000 125 214 9,2 75 5 19100 140 502 10,3 82 6 15000 70 110 5,8 47** **: no rupture observed in transverse bending up to 10% deformation.

[0318] All examples 1 to 5 led to rupture.

[0319] Example 6 therefore corresponds to a material which deforms a lot without breaking. Example 7: Determination of the porosity rate the relative difference between theoretical density and experimental density (general method) a) The required data are:

[0320] The density of the thermoplastic matrix The density of the fibers The weight of the reinforcement: linear mass (g / m) for example for a ¼ inch strip (from a single row) surface mass (g / m 2< ) for example for a wider strip or a fabric b) Measures to be taken:

[0321] The number of samples must be at least 30 for the result to be representative of the material studied.

[0322] The measures to be taken are: The dimensions of the samples taken: Length (if linear mass is known). Length and width (if surface mass is known). The experimental density of the samples taken: Mass measurements in air and in water. The measurement of the fiber content is determined according to ISO 1172:1999 or by thermogravimetric analysis (TGA) as determined for example in the document B. Benzler, Applikationslabor, Mettler Toledo, Giesen, UserCom 1 / 2001.

[0323] The measurement of carbon fiber content can be determined according to ISO 14127:2008.

[0324] Determination of the theoretical mass fiber rate: a) Determination of the theoretical mass fiber rate: %Mf th = m l . L Me air With m I the linear mass of the tape, L the length of the sample and Me airthe mass of the sample measured in air. The variation in the mass rate of fibers is assumed to be directly related to a variation in the matrix rate without taking into account the variation in the quantity of fibers in the reinforcement. b) Determination of the theoretical density: d th = 1 1 − %Mf th d m + %Mf th d f

[0325] With dm And df the respective densities of the matrix and the fibers.

[0326] The theoretical density thus calculated is the accessible density if there is no porosity in the samples. c) Evaluation of porosity:

[0327] Porosity is then the relative difference between theoretical density and experimental density.

Claims

1. Impregnated fibrous material comprising at least one continuous-fibre fibrous material present in the form of one or more parallel rovings and at least one thermoplastic polymer matrix, characterized in that said at least one thermoplastic polymer is an amorphous or semicrystalline polymer having a glass transition temperature such that Tg ≥ 40°C, in particular Tg ≥ 100°C, in particular ≥ 120°C, as measured with a differential scanning calorimeter (DSC) after a second heating run according to the standard ISO 11357-2:2013 with a heating and cooling rate of 20°C / min, the content of fibres in said impregnated fibrous material being from 45% to 65% by volume, preferably from 50% to 60% by volume, especially from 54% to 60% by volume, the number-average molecular mass Mn of said thermoplastic polymer being from 11 000 to 25 000 g / mol, the melt viscosity of said thermoplastic polymer being from 80 to 1500 Pa·s, as measured by plane-plane rheology at 1 Hz and 2% deformation, at a temperature of Tg + 220°C.

2. Impregnated fibrous material according to Claim 1, characterized in that the polydispersity index Ip of said thermoplastic polymer is from 2 to 6, in particular from 2 to 3.5, especially from 2.5 to 3.5.

3. Impregnated fibrous material according to Claim 1 or 2, characterized in that said at least one thermoplastic polymer is selected from: polyaryl ether ketones (PAEKs), in particular polyether ether ketone (PEEK); polyaryl ether ketone ketones (PAEKKs), in particular polyether ketone ketone (PEKK); aromatic polyether imides (PEIs); polyaryl sulfones, in particular polyphenylene sulfones (PPSUs); polyaryl sulfides, in particular polyphenylene sulfides (PPSs), polyamides (PAs), in particular semiaromatic polyamides (polyphthalamides) optionally modified by urea units; PEBAs, polyacrylates, in particular polymethyl methacrylate (PMMA); polyolefins, polylactic acid (PLA), polyvinyl alcohol (PVA), and fluoropolymers, in particular polytetrafluoroethylene (PTFE) or polychlorotrifluoroethylene (PCTFE); and mixtures thereof, especially a mixture of PEKK and PEI, preferably from 90-10% by weight to 60-40% by weight, in particular from 90-10% by weight to 70-30% by weight.

4. Impregnated fibrous material according to Claims 1 to 3, characterized in that the number-average molecular mass Mn of said thermoplastic polymer is from 14 000 to 25 000 and preferably from 15 000 to 21 000 and the melt viscosity of said thermoplastic polymer is from 150 to 1500 Pa·s and preferably from 200 to 750 Pa·s at a temperature of Tg + 220°C and said thermoplastic polymer is a polymer of Tg ≥ 130°C.

5. Impregnated fibrous material according to Claim 4, characterized in that said at least one thermoplastic polymer is a polyamide, in particular a thermally stabilized polyamide.

6. Impregnated fibrous material according to Claim 5, characterized in that said polyamide is selected from semiaromatic polyamides.

7. Fibrous material according to Claim 6, characterized in that said semiaromatic polyamide is modified by urea units and selected from a semiaromatic polyamide of formula X / YAr, especially a semiaromatic polyamide of formula A / XT wherein A is selected from a structural element obtained from an amino acid, a structural element obtained from a lactam and a structural element corresponding to the formula (Ca-diamine)-(Cb-diacid), with a representing the number of carbon atoms in the diamine and b representing the number of carbon atoms in the diacid, a and b each being between 4 and 36, advantageously between 9 and 18, the (Ca-diamine) structural element being selected from linear or branched aliphatic diamines, cycloaliphatic diamines and alkylaromatic diamines and the (Cb-diacid) structural element being selected from linear or branched aliphatic diacids, cycloaliphatic diacids and aromatic diacids; X.T denotes a structural element obtained from the polycondensation of a Cx-diamine and terephthalic acid, with x representing the number of carbon atoms in the Cx-diamine, x being between 6 and 36, advantageously between 9 and 18, especially a polyamide of formula A / 6T, A / 9T, A / 10T or A / 11T, A being as defined above, in particular a polyamide PA 6 / 6T, a PA 66 / 6T, a PA 6I / 6T, a PA MXDT / 6T, a PA MPMDT / 6T, a PA PA11 / 10T, a PA 11 / 6T / 10T, a PA MXDT / 10T, a PA MPMDT / 10T, a PA BACT / 10T, a PA BACT / 6T, a PA 11 / BACT, a PA BACT / 10T / 6T, a PA 11 / BACT / 6T, PA 11 / MPMDT / 6T, a PA 11 / BACT / 10T, a PA 11 / MXDT / 10T or a PA 11 / MXDT / 6T.

8. Impregnated fibrous material according to Claim 6 or 7, characterized in that said semiaromatic polyamide is selected from PA MXDT / 6T, PA MPMDT / 6T, PA 11 / BACT, PA 11 / 6T / 10T, PA MXDT / 10T, PA MPMDT / 10T, PA BACT / 10T, PA BACT / 6T, PA BACT / 10T / 6T, PA 11 / BACT / 6T, PA 11 / MPMDT / 6T, PA 11 / BACT / 10T, PA 11 / MXDT / 10T and PA 11 / MXDT / 6T.

9. Impregnated fibrous material according to Claims 1 to 3, characterized in that the number-average molecular mass Mn of said thermoplastic polymer is from 11 000 to 20 000 g / mol and preferably from 12 000 to 18 000, the melt viscosity of said thermoplastic polymer is from 80 to 650 Pa·s and preferably from 100 to 450 Pa·s at a temperature of Tg + 220°C and said thermoplastic polymer is a polyamide of Tg < 130°C.

10. Impregnated fibrous material according to Claim 9, characterized in that said polyamide of Tg < 130°C is selected from aliphatic polyamides, cycloaliphatic polyamides and semiaromatic polyamides of Tg less than 130°C, in particular aliphatic polyamides and cycloaliphatic polyamides.

11. Impregnated fibrous material according to Claim 10, characterized in that said aliphatic polyamide is selected from polyamide 6 (PA-6), polyamide 11 (PA-11), polyamide 12 (PA-12), polyamide 66 (PA-66), polyamide 46 (PA-46), polyamide 610 (PA-610), polyamide 612 (PA-612), polyamide 1010 (PA-1010), polyamide 1012 (PA-1012), polyamide 11 / 1010, polyamide 12 / 1010 or a mixture thereof or a copolyamide thereof, and block copolymers, especially polyamide / polyether (PEBA), and semiaromatic polyamides are selected from MXD10, MXD6, PA 6 / 6T, PA 66 / 6T, PA 6I / 6T, MPMDT / 10T, 11 / MPMDT / 10T, MPMDT / 6T, PA BACT / 10T, PA 11 / BACT / 10T, MXDT / 10 and PA 11 / MXDT / 10T.

12. Impregnated fibrous material according to any of Claims 1 to 11, characterized in that the number of fibres in said fibrous material for carbon fibres is greater than or equal to 3K, in particular greater than or equal to 6K, especially greater than or equal to 12K, in particular selected from 12K, 24K, 48K, 50K and 400K, especially 12K, 24K, 48K and 50K, or the grammage for the glass fibre is greater than or equal to 1200 tex, especially greater than or equal to 2400 tex, or greater than or equal to 4800 tex.

13. Impregnated fibrous material according to any of Claims 1 to 12, characterized in that the fibres of the fibrous material are not sized.

14. Impregnated fibrous material according to any of Claims 1 to 13, characterized in that the content of fibres by volume is constant in at least 70% of the volume of the impregnated fibrous material, especially in at least 80% of the volume of the impregnated fibrous material, in particular in at least 90% of the volume of the impregnated fibrous material, more particularly in at least 95% of the volume of the impregnated fibrous material.

15. Impregnated fibrous material according to any of Claims 1 to 14, characterized in that the degree of porosity in said impregnated fibrous material is less than 10%, especially less than 5%, in particular less than 2%, said degree of porosity corresponds to the degree of closed porosity and is determined as being the relative difference between the theoretical density and the experimental density of said impregnated fibrous material as described in the examples section of the description.

16. Impregnated fibrous material according to any of Claims 1 to 15, characterized in that said impregnated fibrous material comprises a single layer.

17. Impregnated fibrous material according to any of Claims 1 to 16, characterized in that said fibrous material comprises continuous fibres selected from carbon fibres, glass fibres, silicon carbide fibres, basalt fibres, silica fibres, natural fibres, in particular flax or hemp fibres, lignin fibres, bamboo fibres, sisal fibres, silk fibres, or cellulose fibres, in particular viscose fibres, or amorphous thermoplastic fibres having a glass transition temperature Tg above the Tg of said polymer or of said mixture of polymers when the latter is amorphous or above the Tm of said polymer or of said mixture of polymers when the latter is semicrystalline, or semicrystalline thermoplastic fibres having a melting temperature Tm above the Tg of said polymer or of said mixture of polymers when the latter is amorphous or above the Tm of said polymer or of said mixture of polymers when the latter is semicrystalline, or a mixture of two or more of said fibres, preferably a mixture of carbon, glass or silicon carbide fibres, in particular carbon fibres.

18. Impregnated fibrous material according to any of Claims 1 to 17, characterized in that said thermoplastic polymer further comprises carbon-based fillers, in particular carbon black or carbon-based nanofillers, preferably selected from graphenes, carbon nanotubes, carbon nanofibrils or mixtures thereof.

19. Impregnated fibrous material according to any of Claims 1 to 18, characterized in that said thermoplastic prepolymer further comprises liquid crystal polymers or cyclized poly(butylene terephthalate), or mixtures containing said liquid crystal polymers or said cyclized poly(butylene terephthalate) as additives.

20. Impregnated fibrous material according to any of Claims 1 to 19, characterized in that said impregnated fibrous material is non-flexible, i.e. that it is unable to assume a complex shape at room temperature and can do so only above the Tm of the resin.

21. Process for preparing an impregnated fibrous material as defined in any of Claims 1 to 20, characterized in that it comprises a preimpregnation step or a step of impregnating said fibrous material with at least thermoplastic polymer that is an amorphous or semicrystalline polymer having a glass transition temperature such that Tg ≥ 40°C, especially Tg ≥ 100°C, in particular ≥ 120°C, the content of fibres in said impregnated fibrous material being from 45% to 65% by volume, preferably from 50% to 60% by volume, especially from 54% to 60% by volume, the number-average molecular mass Mn of said thermoplastic polymer being from 11 000 to 25 000 g / mol, the melt viscosity of said thermoplastic polymer being from 80 to 1500 Pa·s,as measured by plane-plane rheology at 1 Hz and 2% deformation, at a temperature of Tg + 220°C.

22. Process for preparing an impregnated fibrous material according to Claim 21, characterized in that it comprises a step of impregnating said fibrous material with at least thermoplastic polymer, the number-average molecular mass Mn of said thermoplastic polymer being from 11 000 to 20 000 g / mol and preferably from 12 000 to 18 000, the melt viscosity of said thermoplastic polymer is from 80 to 650 Pa·s and preferably from 100 to 450 Pa·s at a temperature of Tg + 220°C, and said thermoplastic polymer being a polyamide of Tg < 130°C.

23. Process according to Claim 22, characterized in that said impregnation step is carried out by the molten route, especially at high speed, in particular at a speed of at least 1 to 10 m / min for the molten route, in particular of at least 2 m / min.

24. Process according to Claim 22 or 23, characterized in that it comprises the following steps: i) impregnating a fibrous material with at least one non-reactive thermoplastic polymer by the molten route, especially by pultrusion, by crosshead extrusion of molten polymer, to obtain an impregnated fibrous material, said preimpregnation step being carried out with at least thermoplastic polymer, the number-average molecular mass Mn of said thermoplastic polymer being from 11 000 to 20 000 g / mol and preferably from 12 000 to 18 000, the melt viscosity of said thermoplastic polymer is from 80 to 650 Pa·s and preferably from 100 to 450 Pa·s at a temperature of Tg + 220°C, and said thermoplastic polymer being a polyamide of Tg < 130°C, i) optionally a step of shaping and calibrating said impregnated fibrous material to obtain an impregnated fibrous material consisting of a ribbon in the form of a thin strip having a thickness of from 0.2 to 5 mm and preferably 0.2 to 1.3 mm thick.

25. Process for preparing an impregnated fibrous material according to Claim 21, characterized in that it comprises a step of preimpregnating said fibrous material present in the form of one or more parallel rovings with at least one non-reactive thermoplastic polymer, the number-average molecular mass Mn of said thermoplastic polymer is from 14 000 to 25 000 and preferably from 15 000 to 21 000, and the melt viscosity of said thermoplastic polymer is from 150 to 1500 Pa·s and preferably from 200 to 750 Pa·s at a temperature of Tg + 220°C, and said thermoplastic polymer is a polymer of Tg ≥ 130°C.

26. Process according to Claim 25, characterized in that said preimpregnation is carried out with a system selected from a fluidized bed, spraying with a spray gun, continuous passage of the fibres through an aqueous dispersion of powder of said non-reactive thermoplastic polymer or aqueous dispersion of particles of said thermoplastic polymer or aqueous emulsion or suspension of said non-reactive thermoplastic polymer, especially at high speed.

27. Process according to Claim 25 or 26, characterized in that it comprises at least one step of tensioning-free heating of said preimpregnated fibrous material.

28. Process according to Claim 25 or 26, characterized in that it comprises at least one step of heating carried out by means of at least one tension device (E) and at least one heating system, said roving or said rovings being in contact with part or all of the surface of said at least one tension device (E) and running partially or completely over the surface of said at least one tension device (E) in the heating system.

29. Process according to either of Claims 27 and 28, characterized in that the heating system is selected from an infrared lamp, a UV lamp, convection heating, microwave heating, laser heating and high-frequency (HF) heating.

30. Process according to any of Claims 25 to 29, characterized in that it comprises the following steps: i) preimpregnating a fibrous material with at least one non-reactive thermoplastic polymer by means of a fluidized bed in a tank optionally equipped with at least one tension device (E'), by spraying with a nozzle or spray gun by the dry route into a tank optionally equipped with at least one tension device (E') to obtain a preimpregnated fibrous material, said preimpregnation step being carried out with at least one non-reactive thermoplastic polymer, the number-average molecular mass Mn of said thermoplastic polymer is from 14 000 to 25 000 and preferably from 15 000 to 21 000 and the melt viscosity of said thermoplastic polymer is from 150 to 1500 Pa·s and preferably from 200 to 750 Pa·s at a temperature of Tg + 220°C and said thermoplastic polymer is a polymer of Tg ≥ 130°C, ii) a step of tensioning-free heating of said preimpregnated fibrous material to obtain a preimpregnated fibrous material, iii) a step of heating carried out by means of at least one tension device (E) and at least one heating system, as defined in Claim 28 or 29, to obtain an impregnated fibrous material, iv) optionally a step of shaping and calibrating the roving or said parallel rovings of said impregnated fibrous material to obtain an impregnated fibrous material consisting of a ribbon in the form of a thin strip.

31. Process according to any of Claims 25 to 29, characterized in that it comprises the following steps: (i) preimpregnating a fibrous material with at least one non-reactive thermoplastic polymer, especially by continuous passage of the fibres through a fluid bed of dry polymer powder, an aqueous dispersion of polymer powder or aqueous dispersion of polymer particles or aqueous polymer emulsion or suspension, said preimpregnation step being carried out by at least thermoplastic polymer and said thermoplastic polymer is a polymer having a Tg ≥ 130°C, said non-reactive thermoplastic polymer having a number-average molecular mass Mn of said thermoplastic polymer from 14 000 to 25 000 and preferably from 15 000 to 21 000 and the melt viscosity of said thermoplastic polymer is from 150 to 1500 Pa·s and preferably from 200 to 750 Pa·s,as measured by plane-plane rheology at 1 Hz and 2% deformation, at a temperature of Tg + 220°C, ii) a step of tensioning-free heating of said preimpregnated fibrous material to obtain an impregnated fibrous material, iii) optionally a step of heating carried out by means of at least one tension device (E) and at least one heating system to obtain an impregnated fibrous material, iv) optionally a step of shaping and calibrating the roving or said parallel rovings of said impregnated fibrous material to obtain an impregnated fibrous material consisting of a ribbon in the form of a thin strip.

32. Process according to any of Claims 21 to 31, characterized in that one or more tension device(s) (E") is / are present upstream of said system.

33. Process according to any of Claims 25 to 32, characterized in that it is carried out for the dry powder route at a speed of from 5 to 30 m / min and for the aqueous dispersion at a speed of at least 15 m / min.

34. Use of an impregnated fibrous material, as defined in any of Claims 1 to 20, for preparing ribbons suitable for the production of three-dimensional composite parts, by automated layup of said ribbons using a robot.

35. Use of an impregnated fibrous material, as defined in any of Claims 1 to 20, for preparing thermoformable sheets.

36. Use according to Claim 35, characterized in that the impregnated fibrous material is precut into pieces, said pieces being randomly associated or oriented for preparing the thermoformable sheet.

37. Use of at least one non-reactive thermoplastic polymer, said at least one non-reactive thermoplastic polymer being an amorphous or semicrystalline thermoplastic polymer having a glass transition temperature such that Tg ≥ 40°C, especially Tg ≥ 100°C, in particular ≥ 120°C, the content of fibres in said impregnated fibrous material being from 45% to 65% by volume, preferably from 50% to 60% by volume, especially from 54% to 60% by volume, the number-average molecular mass Mn of said thermoplastic polymer being from 11 000 to 25 000 g / mol, the melt viscosity of said thermoplastic polymer being from 80 to 1500 Pa·s,as measured by plane-plane rheology at 1 Hz and 2% deformation, at a temperature of Tg + 220°C, as defined in any of Claims 1 to 11 and 18 to 19, for impregnating a fibrous material.