Method for impregnating fibrous materials with an optimized system for replenishing and washing particulates - Patent Application 20070122999

Abstract

1. A method for producing an impregnated fibrous material comprising at least one fibrous material consisting of continuous fibers and at least one thermoplastic polymer matrix, the method comprising a step of pre-impregnating the fibrous material with a thermoplastic polymer matrix in powder form, characterized in that the pre-impregnation step is carried out dry in a tank (20) containing a fluidized bed (22), and the pre-impregnation step is carried out while maintaining the level h of powder present in the tank (20) and the mass m of powder substantially constant, the level h ranging from h to h -3%, in particular h -2%, during the pre-impregnation step, where h is the initial level of powder in the tank (20) at the start of the pre-impregnation step, and the mass m ranging from m to m ±0.5%, during the pre-impregnation step, where m is the initial mass of powder in the tank (20) at the start of the pre-impregnation step.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing an impregnated fibrous material comprising at least one fibrous material made of continuous fibers and at least one thermoplastic polymer matrix, the method comprising the step of pre-impregnating the fibrous material with a thermoplastic polymer matrix in powder form in a fluidized bed, wherein the level h of the powder and the mass m of the powder present in the tank (20) are kept substantially constant within the tank (20) during the pre-impregnation step.

[0002] In other words, said level h of the powder is from h i to h i - 3%, in particular h i - 2%, where h i is the initial level of the powder in said tank (20) at the start of the pre-impregnation step, and said mass m is from m i to m i ± 0.5% during the pre-impregnation step, where m i is the initial mass of the powder in said tank (20) at the start of the pre-impregnation step.

[0003] As used herein, the expression "fibrous material" is understood to mean an assembly of reinforcing fibers. Before shaping the fibrous material, the fibrous material is in the form of rovings. After shaping, the fibrous material is in the form of ribbons (or tapes), strips or sheets. These assemblies constitute unidirectional reinforcements or fabrics or non-woven fabrics (NCF).

[0004] As used herein, the term "strip" is used to refer to a strip of fibrous material having a width of 400 mm or more. The term "ribbon" is used to refer to a ribbon having a calibrated width of 400 mm or less.

[0005] The quality of the impregnation of a particularly highly viscous thermoplastic polymer into reinforcing fibers for manufacturing a thermoplastic prepreg tape requires complete control of the amount of the impregnating polymer and the quality of the distribution of this polymer within the rovings of the reinforcing fibers during the impregnation process. Many patents or patent applications, for example, WO2018 / 229114, WO2018 / 234436, WO2018 / 234439, and EP2788408 describe the fact that the fiber drafting is an essential parameter for achieving a uniform quality polymer impregnation into the fibers for the final tape.

[0006] Generally, the drafting of reinforcing fibers such as carbon fibers is produced via mechanical, pneumatic, and / or vibrating devices. The main drawbacks of these methods are causing misorientation of the fibers within the rovings (drafting by blowing out or suction) and / or mechanical degradation of the fibers due to the application of overly high transverse stresses.

[0007] The generation of drafting may cause fiber breakage or at least partial degradation of these fibers, no matter what system is used. Next, a kind of fiber fluff called "fly" is formed. Generally consisting of accumulative pieces of several fibers, this fly is mainly generated at the contact points between the fibers and the members of the impregnation line (guide fingers, support rollers, etc.). The greater the mechanical stress applied, the more fly tends to be generated. Next, the fly generated especially in the pre-impregnation bath and finally accumulating is observed over time. In a fluidized bed type pre-impregnation bath, the fly locally reduces the quality of fluidization, and the quality of the fluidized bed continuously decreases. As a result, the level of the fluidized bed decreases, and the local concentration of powder particles changes. At that time, a non-uniform powder bath that makes it impossible to accurately and continuously impregnate during the process is observed. The amount of powder captured by the fiber rovings, and thus the amount of polymer impregnated into the tape, tends to decrease over time.

[0008] It may appear in dead corners, and caking of powder particles not caused by the accumulation of lint is also observed. It is well known to those skilled in the art that when all the powder comes into contact with the wall of the tank, it will finally settle, especially in the corners of the tank, due to the decrease in powder velocity, causing caking. In addition, due to the contact between them and generally their non-spherical shapes, the powder will also agglomerate and thus settle. This has an overall impact on the height of the powder level in the tank and thus reduces it.

[0009] Document FR2659595 describes a method for impregnating fibers with an aerosol in which the powder is supplied by a fluidized bed including a system for reintroducing previously introduced but unimpregnated particles, and the powder particles are intentionally electrostatically charged.

[0010] Document EP0246167 describes a method for impregnating fibers with an aerosol in which the volume or weight of the polymer and fibers being carried is maintained at a preselected value.

[0011] Document WO2018 / 234436 describes an electrostatic method for impregnating fibers.

[0012] The particle sizes used in the fluidized bed pre-impregnation process of the powder generally concentrate in the range of 100 - 200 μm and are accompanied by relatively large deviations (D10 and D90 far from D50) (see in particular documents WO2018115737A1 and WO2018115738A1). This dispersion is necessary to obtain uniform and stable fluidization and an optimized quality of pre-impregnation. Due to the large difference in particle sizes between the smallest particles (particle sizes of several μm or fine particles) and the largest particles (for example, up to 500 - 600 μm), the fine particles scatter from the fluidization tank (20) (more than 99% by volume of the scattered powder has a particle size between 0.01 μm and 60 μm). The scattering of these fine particles causes several major problems:

[0013] Depletion of the fluidized bed from the perspective of fine particles, which can cause changes in the quality of the pre-impregnation of the fiber rovings and the stability of the fluid bath and also its level.

[0014] A rather significant loss of material, and thus a reduction in the profitability of the manufacturing process. It would be preferable to be able to capture and improve said fine particles.

[0015] QHSE (Quality, Health, Safety and Environment) problems caused by the scattering of fine particles (<10 μm) to the operator and the equipment.

[0016] Similarly, during production, it is necessary to replenish the pre-impregnation tank (20) with a "stock solution" having a composition equivalent to that initially charged to the pre-impregnation bath. Therefore, in a fluidized bed system, in order to obtain a product that is sufficiently impregnated and constant in terms of polymer content, it is necessary to maintain not only a constant powder height but also a constant powder mass in the fluidization tank (20). The replenishment of the powder is generally carried out manually and periodically, causing small but definite fluctuations in the composition of the bath during the manufacturing time.

[0017] Therefore, it is necessary to improve the various problems listed above.

[0018] Therefore, the present invention is a method for manufacturing an impregnated fibrous material comprising at least one fibrous material made of continuous fibers and at least one thermoplastic polymer matrix, the method comprising a step of pre-impregnating the fibrous material with a thermoplastic polymer matrix in powder form, wherein the pre-impregnation step is carried out dry in a tank (20) comprising a fluidized bed (22), and the pre-impregnation step is carried out while substantially maintaining a constant level h of the powder and a constant mass m of the powder present in the tank (20), the level h being from h i to h i - 3%, particularly h i - 2%, where h i is the initial level of the powder in the tank (20) at the start of the pre-impregnation step, and the mass m is from m i to mi is ±0.5%, where m i is the initial mass of the powder in the tank (20) at the start of the pre-impregnation process, a method characterized by.

[0019] The pre-impregnation process is carried out with the powder level h and mass m maintained substantially constant, which is essential in the method of the present invention. In fact, at the moment when the pre-impregnation process is started and fluidization begins, the inside of the tank (20) has the initial height h of the fluidized powder i or the initial level, and the inside of the tank (20) has the initial mass m of the powder i is.

[0020] During the pre-impregnation process, both the level of the powder present in the tank (20) and the mass of the powder must be kept substantially constant, that is, during the pre-impregnation process, in the tank (20), the level h must be continuously maintained substantially constant; in other words, the level h is from h i to h i -3%, especially h i -2%, where h i is the initial level of the powder in the tank (20) at the start of the pre-impregnation process, and the mass m of the powder must be continuously maintained substantially constant; in other words, the mass m is, during the pre-impregnation process, from m i to m i ±0.5%, where m i is the initial mass of the powder in the tank (20) at the start of the pre-impregnation process.

[0021] The initial level of the powder h i can be measured according to various techniques well known to those skilled in the art using a fluidized bed of powder.

[0022] For example, it can be measured by a sensor, in particular a membrane type position sensor, or by an ultrasonic position measuring device sold, for example, by Flowline (USA), or even by a laser measurement of the level of a fluidized bed in a tank, for example by a laser displacement sensor sold by Keyence (France) or by a continuous level measurement and level detection device sold by Endress and Hauser (France).

[0023] If necessary, averaging of the measured values in the area actually used to carry out the pre-impregnation of the fibers in the fluidized bed can be carried out.

[0024] According to FR2659595 and EP0246167, the fluidized bed has a horizontal plane such as a liquid in a container.

[0025] Therefore, the initial level of the powder along the length and width of the fluidized bed can be easily measured.

[0026] Advantageously, the surface of the fluidized bed used in the present invention is horizontal, especially like a liquid in a container.

[0027] Advantageously, the height of the fluidized bed is constant over the entire width and length of the tank.

[0028] A certain mass of powder in the fluidized bed to maintain a certain pre-impregnation quality over time can be obtained using an automatic system for powder replenishment of the tank based on a weighing device connected to a weighing scale on which the fluidization tank is placed and a fluidized bed level sensor. These metering devices continuously supply the non-useful area of the tank of the fluidization tank so as not to interfere with the process.

[0029] Advantageously, during the implementation of the pre-impregnation process, the level h must be from h i to h i -2%, and the mass m must be from m i to m i ±0.5%.

[0030] In one embodiment, the volume average particle size D50 of the thermoplastic polymer powder particles is from 30 to 300 μm, particularly from 50 to 200 μm, more particularly from 70 to 200 μm.

[0031] The volume particle sizes (D10, D50 and D90) of the thermoplastic polymer powder particles are defined according to standard ISO 9276:2014.

[0032] “D50” corresponds to the volume average particle size, that is, the value of the particle size that divides the population of the inspected particles exactly in two.

[0033] “D90” corresponds to the value at 90% of the cumulative curve of the volume particle size distribution.

[0034] “D10” corresponds to the particle size of 10% of the volume of the particles.

[0035] In one embodiment, the tank (20) is replenished with a thermoplastic polymer matrix in powder form to compensate for the consumption of the thermoplastic polymer matrix by the pre-impregnation of the fibrous material.

[0036] In one embodiment, the particle size of the powder is substantially constant within the tank (20), that is, the maximum variation of D50 is +20%.

[0037] In another embodiment, the particle size of the fine particles of the powder is substantially constant within the tank (20), that is, the maximum variation of D10 is +30%.

[0038] In yet another embodiment, the particle size of the large particles of the powder is substantially constant within the tank (20), that is, the maximum variation of D90 is +10%.

[0039] Advantageously, the particle size of the powder is substantially constant within the tank (20), that is, the maximum variation of D50 is +20%, and the particle size of the fine particles of the powder is substantially constant within the tank (20), that is, the maximum variation of D10 is +30%.

[0040] Advantageously, the particle size of the powder is substantially constant within the tank (20), that is, the maximum variation of D50 is +20%, and the particle size of the large particles of the powder is substantially constant within the tank (20), that is, the maximum variation of D90 is +10%.

[0041] Advantageously, the particle size of the large particles of the powder is substantially constant within the tank (20), that is, the maximum variation of D90 is +10%, and the particle size of the fine particles is substantially constant within the tank (20), that is, the maximum variation of D10 is +30%.

[0042] Advantageously, the particle size of the powder is substantially constant within the tank (20), that is, the maximum variation of D50 is +20%, and the particle size of the fine particles of the powder is substantially constant within the tank (20), that is, the maximum variation of D10 is +30%, and the particle size of the large particles of the powder is substantially constant in the tank (20), that is, the maximum variation of D90 is +10%.

[0043] When the fibrous material enters the fluidized bed, the powder of the thermoplastic polymer matrix present in the tank (20) first settles on the fibrous material and is thus consumed during pre-impregnation, which causes a decrease in the powder level in the tank (20) and also a decrease in the mass of the powder present in the tank (20). Therefore, it is necessary to compensate for the level and mass in the tank (20) by introducing the "stock composition", that is, the initial thermoplastic polymer matrix in powder form, that is, having the same D10, D50, and D90 characteristics.

[0044] However, due to fluidization, the fine particles initially present in the "stock composition" leave the fluidized bed and also the tank (20), which causes variations in D50, D10, and D90 of the "stock composition", even when compensating for the level and mass present in the tank (20) by introducing the "stock composition" into the tank (20).

[0045] Therefore, D50 and / or D90 and / or D10 must be kept constant.

[0046] In one embodiment, the tank (20) includes a fluidized bed (22), and the preliminary impregnation step is carried out with simultaneous stretching of the roving (81a) or the group of rovings between the inlet and the outlet of the fluidized bed (22).

[0047] The term "stretching" means that the width of the fibrous material (or roving) increases with respect to the initial width I of the roving, i.e., the factor that ensures the preliminary impregnation process when the roving enters the system. It is obvious that the average width of the roving (whether it is the initial width or the width after stretching) is determined by averaging the measurements obtained non-contact (laser, LED, etc.) on several spools while it is flat. The initial width does not necessarily correspond to the roving width at the outlet of the fibrous material supply reel.

[0048] In one embodiment, the tank (20) is provided with a scraper.

[0049] As shown above, in any system, the generation of stretching causes breakage of the fiber filaments: Next, "flyers" are formed, especially accumulating over time in the preliminary impregnation bath and locally degrading the quality of fluidization. The quality of the fluidized bed continuously deteriorates. Furthermore, especially in the dead corners of the fluidized bed, caking of the powder particles themselves occurs. Due to both the powder flyers and the "natural" caking, the level of the fluidized bed decreases overall and the local concentration of the powder particles changes. As a result, a scraper is required to break up the accumulated powder block and thereby resuspend the powder particles.

[0050] In one embodiment, the scraper is automatically used when the level h < h i -3%, especially when h < h i -2%.

[0051] To obtain a substantially constant level of the fluidized bed so as to maintain substantially constant pre-impregnation quality over time, when the threshold of the fluidized bed falls below the critical level, the scraper system is automatically and periodically actuated. The purpose of this scraper is not only to discharge the fluff in the unused area of the fluidization tank, but also to decake the powder accumulated in the less turbulent area of the tank (the caking phenomenon well known to those skilled in the art of fluidization). It can take several physical forms: independent fiber pieces several millimeters or centimeters in length, small balls formed by winding continuous fibers on themselves, clusters of continuous short fibers in the form of lumps in a suspension, lumps of agglomerated powder, etc.

[0052] In one embodiment, the tank (20) is provided with a lateral suction system that sucks fine particles with a particle size of 0.01 to 60 μm that leave the tank (20) during fluidization.

[0053] Advantageously, 99% of the fine particles that leave the tank (20) during fluidization have a particle size of 0.01 to 60 μm.

[0054] The particle size of the particles leaving the tank can be measured by common techniques known to those skilled in the art (for example, laser particle size measurement of the powder that is scattered, collected, and then analyzed over several manufacturing processes).

[0055] In another embodiment, the tank (20) is provided with a lateral suction system that sucks fine particles having a D50 of 0.01 to 60 μm that leave the tank (20) during fluidization.

[0056] Advantageously, the sucked particles are continuously re-introduced into the tank (20).

[0057] In addition to the natural consumption of the powder, the generation of fluff, and the formation of agglomerates of the aggregated powder by the preliminary impregnation process, the fine particles of the "stock composition" scatter over the fluidization tank, thus causing changes in the D50, D10, and D90 of the "stock composition", which, despite the input of the "stock composition", disrupt the quality, uniformity, and quantity of the preliminary impregnation of the fibrous material and also reduce the level of the fluidized bed.

[0058] The fine particles consist of particles having a particle size from 0.01 to 60 μm.

[0059] Particles having a particle size of less than 0.01 μm are not initially present in the system.

[0060] Particles having a particle size exceeding 60 μm generally do not scatter over the tank.

[0061] Therefore, it is necessary to recover the fine particles having a particle size from 0.01 to 60 μm that leave the tank (20) during fluidization, which are then re-introduced into the tank.

[0062] Advantageously, the lateral suction system is provided with a sorting grid to prevent particles exceeding 60 μm from being sucked and re-introduced into the tank.

[0063] The "stock composition" of the powder added to the tank may also include a part of the particles recovered by the suction / recovery system according to their particle sizes.

[0064] Advantageously, the tank (20) is provided with a scraper and a lateral suction system for sucking fine particles having a particle size from 0.01 to 60 μm that leave the tank (20).

[0065] Advantageously, 99% of the fine particles that leave the tank (20) during fluidization have a particle size from 0.01 to 60 μm.

[0066] Advantageously, the tank (20) is provided with a scraper and a lateral suction system that sucks fine particles having a D50 of from 0.01 to 60 μm away from the tank (20).

[0067] [Regarding the pre-impregnation process]

[0068] An example of an apparatus for carrying out the manufacturing method is described in International Application WO2015 / 121583 and is shown in FIG. 1 except for the tank (otherwise called a pre-impregnation tank and including in the case of the present invention a fluidized bed provided with a tensioning device that may be a compression roller).

[0069] The pre-impregnation process and the tensioning device may be as described in WO2018 / 115737.

[0070] The compression roller may be fixed or rotating.

[0071] The process of pre-impregnating the fibrous material is carried out by passing one or more rovings through a continuous pre-impregnation apparatus including a tank (20) provided with a fluidized bed (22) of polymer powder in particular.

[0072] The polymer powder or polymer is introduced into the tank and suspended in a gas G (for example, air) flowing into the tank through the hopper 21. The rovings are circulated through this fluidized bed 22.

[0073] The tank may have any shape, in particular cylindrical or parallelepiped, in particular cuboid or cube, advantageously cuboid.

[0074] The tank may be an open-type or closed-type tank. Advantageously, it is open-type.

[0075] When the tank is of the closed type, a sealing system is provided so that the polymer powder does not come out of the tank.

[0076] Therefore, this pre-impregnation step is carried out by a drying path, i.e., the thermoplastic polymer matrix is in powder form suspended in a gas, particularly air, and cannot be dispersed in a solvent or water.

[0077] Each roving to be pre-impregnated is unwound from a device (10) equipped with a reel (11) under the tension generated by a roll (not shown). Preferably, the device (10) includes a plurality of reels (11), and each reel can unwind one roving to be impregnated. Therefore, several fiber rovings can be pre-impregnated simultaneously. Each reel (11) is equipped with a brake (not shown) that applies tension to each fiber roving. In this case, the alignment module (12) enables the fiber rovings to be arranged parallel to each other. In this way, the fiber rovings cannot contact each other, thereby preventing mechanical degradation of the fibers due to the fibers rubbing against themselves.

[0078] Next, the fiber roving or parallel fiber rovings pass through a tank (20) that includes a fluidized bed (22) and is equipped with a tension device that is a compression roller (23) in the case of FIG. 1. Next, after controlling the residence time in the powder, the fiber roving or parallel fiber rovings exit the tank after impregnation.

[0079] By controlling the residence time in the powder, the resin content can be sufficiently controlled, and it becomes possible to pre-impregnate the fibrous material with the thermoplastic polymer matrix uniformly.

[0080] The use of at least one tension device improves impregnation compared to prior art methods, and in particular, the impregnation is a complete impregnation.

[0081] The tension device is understood to mean any system through which the roving can pass through the tank. The tension device can take any shape as long as the roving can run on it.

[0082] This impregnation is carried out in order to enable the polymer powder to penetrate into the core of the fiber rovings and to adhere sufficiently to the fibers so that the rovings coated with the powder can withstand transportation from the tank. Next, the powder-preimpregnated rovings are sent to a heated calendar device, can be preheated before calendaring, and can be optionally heated after calendaring.

[0083] In some cases, this pre-impregnation step can be completed by covering the pre-impregnated rovings or group of rovings at just the outlet of the tank (20) and immediately before the calendaring step in order to pre-impregnate the powder in a fluidized bed (22). For this purpose, the outlet airlock of the tank (20) (fluidized bed 22) can be connected to a coating device (30) that can include a coating crosshead, as described also in patent EP0406067. The coating polymer can be the same as or different from the fluidized bed polymer powder. Preferably, it is of the same type. Such a coating not only completes the step of pre-impregnating the fibers to obtain a desired final volume content of polymer within the desired range and to avoid the presence of a fiber content on the surface of the pre-impregnated rovings that is too high locally and thus has an adverse effect on welding the tape during the manufacture of composite parts, but also makes it possible to improve the performance of the resulting composite material in order to particularly obtain a so-called "ready-to-use" fibrous material of good quality.

[0084] The method of the present invention described above is carried out by a dry route excluding an electrostatic process with intentional charging.

[0085] The expression "with intentional charging" means that a potential difference is applied between the fibrous material and the powder. The charge is particularly controlled and amplified. Next, the powder particles impregnate the fibrous material by attracting the charged powder to the fibers. The powder can be charged negatively or positively and the fibers can be charged oppositely (positively or negatively) by various means (such as the potential difference between two metal electrodes, mechanical friction on metal parts, etc.).

[0086] The method of the present invention does not rule out the presence of electrostatic charges, which may appear on the members of the implementation device by friction of the fibrous material before or inside the tank, but in any case are unintended charges.

[0087] Advantageously, the fiber content in the impregnated fibrous material is from 45% to 65% by volume, preferably from 50% to 60% by volume, particularly from 54% to 60% by volume.

[0088] With less than 45% fibers, the reinforcement is not sufficient with respect to the mechanical properties.

[0089] Above 65%, the process limits are reached and the mechanical properties are lost again.

[0090] When the fibrous material, such as glass fiber, has a sizing agent, an optional desizing step can be carried out before the fibrous material enters the tank. The term "sizing" means the surface treatment applied to the reinforcing fibers (textile sizing) and fabrics (plastic sizing) when leaving the spinneret.

[0091] The "textile" sizing treatment applied to the filaments when leaving the spinneret consists of depositing a binder that ensures the cohesion of the filaments to each other, reduces wear, facilitates subsequent handling operations (weaving, drape forming, knitting), and prevents the formation of electrostatic charges.

[0092] The "plastic" sizing treatment or "finishing" applied to the woven fabric consists of depositing a crosslinking agent, the role of which is to ensure the physicochemical bond between the fiber and the resin and to protect the fiber from its surroundings.

[0093] Advantageously, the fiber content in the impregnated fibrous material is from 50% to 60% by volume, particularly from 54% to 60% by volume.

[0094] Advantageously, the residence time in the powder is from 0.01 seconds to 10 seconds, preferably from 0.1 seconds to 5 seconds, particularly from 0.1 seconds to 3 seconds.

[0095] The residence time of the fibrous material in the powder is essential for the impregnation of the fibrous material, particularly for complete impregnation.

[0096] If it is less than 0.1 second, the impregnation has not reached the core.

[0097] If it exceeds 10 seconds, the amount of the polymer matrix impregnated into the fibrous material is too large, and the mechanical properties of the pre-impregnated fibrous material become insufficient.

[0098] Advantageously, the tank used in the method of the present invention has a fluidized bed, and the pre-impregnation step is carried out together with the simultaneous extension of the roving or the roving group between the inlet and the outlet of the fluidized bed.

[0099] The expression "inlet of the fluidized bed" corresponds to the vertical tangent of the edge of the tank equipped with the fluidized bed.

[0100] The expression "outlet of the fluidized bed" corresponds to the vertical tangent of the other edge of the tank equipped with the fluidized bed.

[0101] Therefore, depending on the shape of the tank, the distance between its inlet and outlet corresponds to the diameter in the case of a cylinder, the side in the case of a cube, or the width or length in the case of a rectangular parallelepiped. The extension is to individualize each constituent filament of the roving from the other filaments surrounding it in its closest space as much as possible. It corresponds to the lateral extension of the roving.

[0102] In other words, the lateral extension or width of the roving increases between the inlet of the fluidized bed (or the tank equipped with the fluidized bed) and the outlet of the fluidized bed (or the tank equipped with the fluidized bed), thus enabling improved impregnation, particularly complete impregnation, of the fibrous material.

[0103] The fluidized bed may be of an open type or a closed type, particularly an open type.

[0104] Advantageously, the fluidized bed includes at least one tensioning device, and the roving or roving group is in contact with part or all of the surface of the at least one tensioning device.

[0105] FIG. 2 shows details of a tank (20) including a fluidized bed (22) with a height-adjustable tensioning device (82).

[0106] The roving (81a) is in contact with part or all of the surface of the at least one tensioning device and thus corresponds to the pre-impregnation roving that runs partially or completely on the surface of the tensioning device (82), and the system (82) is immersed in the fluidized bed where impregnation takes place. Next, after controlling the residence time in the powder, the roving emerges from the tank (81b).

[0107] The roving (81a) may or may not be in contact with an edge (83a) of the tank, which can be a rotating or fixed roller or a parallelepiped edge.

[0108] Advantageously, the roving (81a) is optionally in contact with an edge (83a) of the tank.

[0109] Advantageously, the edge (83b) of the tank is a roller, particularly a cylindrical rotating roller.

[0110] The roving (81b) may or may not be in contact with an edge (83b) of the tank, which can be a roller, particularly a cylindrical rotating or fixed roller, or a parallelepiped edge.

[0111] Advantageously, the roving (81b) is in contact with an edge (83b) of the tank.

[0112] Advantageously, the edge (83b) of the tank is a roller, particularly a cylindrical rotating roller.

[0113] Advantageously, the roving (81a) is in contact with the edge (83a) of the tank, the edge (83b) of the tank is a roller, in particular a cylindrical rotating roller, the roving (81b) is in contact with the edge (83b) of the tank, and the edge (83b) of the tank is a roller, in particular a cylindrical rotating roller.

[0114] Advantageously, the tensioning device is orthogonal to the direction of the roving or the group of rovings.

[0115] Advantageously, the stretching of the roving or the group of rovings is carried out at at least the same height as the at least one tensioning device.

[0116] Therefore, the stretching of the roving is mainly carried out at the same height as the tensioning device, but if there is contact between the roving and the edge, it may also be carried out at the same height as the edge of the tank.

[0117] In another embodiment, the at least one tensioning device is a convex, concave, or cylindrical compression roller.

[0118] Convex is advantageous for stretching, and concave is disadvantageous for stretching but is still carried out.

[0119] The expression "compression roller" means that the running roving partially or completely presses against the surface of the compression roller, which induces the stretching of the roving.

[0120] Advantageously, the at least one compression roller is cylindrical, and the stretching rate of the roving or the group of rovings between the inlet and the outlet of the fluidized bed is between 1% and 400%, preferably between 30% and 400%, preferably between 30% and 150%, preferably between 50% and 150%.

[0121] Stretching depends on the fibrous material used. For example, the stretching of carbon fiber material is much greater than that of linen fiber.

[0122] The extension also depends on the number of fibers or filaments within the roving, their average diameter, and their aggregation by size.

[0123] The diameter of the at least one compression roller is from 3 mm to 500 mm, preferably from 10 mm to 100 mm, particularly from 20 mm to 60 mm.

[0124] If it is less than 3 mm, the deformation of the fibers induced by the compression roller is too large.

[0125] Advantageously, the compression roller is cylindrical, without grooves, and particularly made of metal.

[0126] When the tensioning device is at least one compression roller, according to a first variant, a single compression roller is present in the fluidized bed, and the impregnation is carried out at an angle α1 formed by the roving or the group of rovings between the starting part of the compression roller and the perpendicular tangent to the compression roller.

[0127] The angle α1 formed by the roving or the group of rovings between the starting part of the compression roller and the perpendicular tangent to the compression roller enables the formation of a region where the powder will concentrate, and thus, together with the simultaneous extension of the roving by the compression roller, enables impregnation over a larger roving width, thus bringing about a "corner effect" that enables improved impregnation compared to the prior art. When combined with a controlled residence time, complete impregnation becomes possible.

[0128] Advantageously, the angle α1 is from 0 to 89°, preferably from 5° to 85°, preferably from 5° to 45°, preferably from 5° to 30°.

[0129] However, an angle α1 from 0 to 5° may cause a risk of mechanical stress, resulting in fiber breakage, and an angle α1 from 85° to 89° does not create sufficient mechanical stress to produce the "corner effect".

[0130] Therefore, the value of the angle α1 equal to 0° corresponds to the vertical fiber. Since the height of the cylindrical compression roller is adjustable, it is obvious that the fiber can be arranged vertically.

[0131] Piercing the wall of the tank so that the roving can leave may not be outside the scope of the present invention.

[0132] Advantageously, the edge (83a) of the tank is provided with rollers, in particular the roving or the cylindrical rotating roller on which the roving travels, thus providing a pre-draft.

[0133] Advantageously, one or more tensioning devices are present downstream of the tank with a fluidized bed, and drafting is initiated by the tensioning device.

[0134] Advantageously, drafting is initiated by the tensioning device defined above and continues at the edge (83a) of the tank.

[0135] Next, after passing through the compression roller, the draft is maximized.

[0136] Figure 2 depicts a non-limiting embodiment having a single compression roller with a tank (20) including a fluidized bed (22) in which there is a single cylindrical compression roller. The angle α1 is the angle formed between the vertical tangent of the compression roller and the roving in contact with the roller.

[0137] The arrow on the fiber indicates the running direction of the fiber.

[0138] Advantageously, the level of the powder in the fluidized bed is located at least in the middle of the compression roller.

[0139] The "corner effect" caused by the angle α1 promotes the impregnation of one side, but it is quite obvious that the spreading of the rovings obtained by the compression roller also enables the impregnation of the other side of the rovings. In other words, the impregnation is advantageous on one side of the rovings or the roving group at the angle α1 formed by the rovings or the roving group between the starting part of the at least one compression roller R1 and the vertical tangent of the compression roller R1, but the spreading also enables the impregnation of the other side.

[0140] The angle α1 is as defined above.

[0141] [Regarding the fibrous material] Regarding the fibers constituting the fibrous material, these are, in particular, fibers of mineral, organic or plant origin. Among the fibers of mineral origin, for example, carbon fibers, glass fibers, silicon fibers, basalt or basalt-based fibers, or silica fibers can be mentioned. Among the fibers of organic origin, for example, fibers based on thermoplastic or thermosetting polymers such as semi-aromatic polyamide fibers, aramid fibers or polyolefin fibers can be mentioned. Preferably, they are based on amorphous thermoplastic polymers and have a Tg higher than the glass transition temperature Tg of the thermoplastic polymer or polymer mixture constituting the pre-impregnated matrix when the matrix is amorphous, or a Tg higher than the Tm of the thermoplastic polymer or polymer mixture constituting the pre-impregnated matrix when the matrix is semi-crystalline. Advantageously, they are based on semi-crystalline thermoplastic polymers and have a melting temperature Tm higher than the Tg of the thermoplastic polymer or polymer mixture constituting the pre-impregnated matrix when the matrix is amorphous, or a Tm higher than the Tm of the thermoplastic polymer or polymer mixture constituting the pre-impregnated matrix when the matrix is semi-crystalline. Therefore, during the impregnation of the fibrous material with the thermoplastic matrix of the final composite, there is no risk of the organic fibers constituting the fibrous material melting. Among the fibers of plant origin, mention may be made of flax, hemp, lignin, bamboo, silk, natural fibers based in particular on spider silk, sisal, and other cellulose fibers, in particular viscose fibers. These fibers of plant origin can be used as such, or can be treated or coated with a coating layer for the purpose of facilitating the adhesion and impregnation of a thermoplastic polymer matrix.

[0142] The fibrous material can also be a fabric, knitted fabric, or woven fabric of fibers.

[0143] It can also correspond to fibers having support threads.

[0144] These constituent fibers can be used alone or as a mixture. Thus, organic fibers can be mixed with mineral fibers in order to pre-impregnate them with a thermoplastic polymer and form a pre-impregnated fibrous material.

[0145] Preferably, the fibrous material is formed by continuous fibers of carbon, glass or silicon carbide or mixtures thereof, in particular carbon fibers. The fibrous material is used in the form of rovings or several rovings.

[0146] Also, in the impregnated material, also referred to as "ready-to-use", the thermoplastic polymer or polymer mixture to be impregnated is distributed uniformly and homogeneously around the fibers. In this type of material, the thermoplastic polymer to be impregnated must be dispersed as homogeneously as possible within the fibers in order to obtain a minimum amount of porosity, i.e., a minimum amount of voids between the fibers. Specifically, the presence of pores in this type of material can act as stress concentration points when, for example, placed under mechanical tensile stress, and then form the starting point of damage to the impregnated fibrous material, making it mechanically fragile. Thus, the uniform distribution of the polymer or polymer mixture improves the mechanical strength and uniformity of the composite material formed from these impregnated fibrous materials.

[0147] Therefore, in the case of a so-called "ready-to-use" impregnated material, the fiber content in the impregnated fibrous material is between 45% and 65% by volume, preferably between 50% and 60% by volume, particularly between 54% and 60% by volume.

[0148] The measurement of the impregnation degree can be carried out by image analysis of the cross-section of the ribbon (in particular, using a microscope or a camera or a digital camera) by dividing the surface area of the ribbon impregnated with the polymer by the total surface area of the product (the sum of the impregnated surface area and the surface area of the pores). To obtain a good-quality image, it is preferable to coat the ribbon cut in the transverse direction with a standard polishing resin, polish it according to a standard protocol, and make it possible to observe the sample with a microscope at a magnification of at least 6 times.

[0149] Advantageously, the porosity of the impregnated fibrous material is less than 10%, especially less than 5%, particularly less than 2%.

[0150] It should be noted that it is difficult to achieve a zero porosity. Therefore, advantageously, the porosity is greater than 0% but less than the above-mentioned porosity.

[0151] The porosity corresponds to the closed porosity and can be determined by an electron microscope or, as described in the example part of the present invention, as the relative deviation between the theoretical density and the experimental density of the impregnated fibrous material.

[0152] The fibers that can be part of the composition of the fibrous material can have different linear grammages or titles or titrations or "tex", and / or can be in different numbers in the roving. Therefore, the most commonly used rovings consist of 600 to 4800 tex for glass fibers and 3000 (3K), 6000 (6K), 12000 (12K), 24000 (24K), 48000 (48K), 50000 (50K) or 400000 (400K) fibers for carbon fibers. Carbon fibers generally have a diameter close to 7 - 8 μm, and glass fibers have a diameter of, for example, about 13, 15, 17, or 20 μm.

[0153] It is quite obvious that the elongation depends on the number of fibers present in the fibrous material or roving.

[0154] Thus, for 12K roving, the elongation is 2 to 3 times the initial width I, for 24K roving, the elongation is 2 to 4 times the initial width I, and for 50K roving, the elongation is 1.5 to 2.5 times the initial width I. [Regarding the thermoplastic polymer of the matrix] A thermoplastic or thermoplastic polymer is generally solid at ambient temperature, can be semi-crystalline or amorphous, softens during temperature rise, especially after passing through its glass transition temperature (Tg), and if amorphous, flows at high temperature, or if semi-crystalline, shows a distinct melting when passing through its melting temperature (Tm), and is understood to mean a material that becomes solid again during temperature decrease below its crystallization temperature (in the case of semi-crystalline polymers) and below its glass transition temperature (in the case of amorphous). Tg and Tm are determined by differential scanning calorimetry (DSC) according to standards 11357-2:2013 and 11357-3:2013, respectively. Regarding the polymer constituting the matrix for pre-impregnating the fibrous material, this is preferably a thermoplastic polymer or a mixture of thermoplastic polymers. This thermoplastic polymer or polymer mixture can be ground into powder so as to be used in a device such as a tank, especially in a fluidized bed tank or an aqueous dispersion. The device in the form of a tank, especially a fluidized bed tank, can be open or closed. In some cases, the thermoplastic polymer or thermoplastic polymer mixture further contains a carbon-based filler, especially carbon black or a carbon-based nanofiller, especially graphene and / or carbon nanotubes and / or carbon nanofibers, or a mixture thereof, preferably selected from carbon-based nanofillers. These fillers enable electrical and heat conduction, and as a result, enable the promotion of melting when the polymer matrix is heated. In some cases, the thermoplastic polymer contains at least one additive selected particularly from catalysts, antioxidants, heat stabilizers, UV stabilizers, light stabilizers, lubricants, fillers, plasticizers, flame retardants, nucleating agents, chain extenders, and colorants, conductive agents, heat conductive agents, or mixtures thereof. Advantageously, the additive is selected from flame retardants, conductive agents, and heat conductive agents. According to another variant, the thermoplastic polymer or thermoplastic polymer mixture may further contain a liquid crystal polymer or cyclic polybutylene terephthalate or a mixture containing them, such as the CBT100 resin commercially available from Cyclics. These compounds make it possible, particularly, to fluidize the polymer matrix in the molten state for better penetration into the core of the fibers. Depending on the nature of the polymer or thermoplastic polymer mixture used to produce the prepreg matrix, particularly its melting temperature, any of these compounds is selected. The thermoplastic polymer introduced into the composition of the prepreg matrix of the fibrous material is - Polymers and copolymers of the family of aliphatic or cycloaliphatic polyamides (PA), or semi-aromatic PA (also known as polyphthalamide (PPA)), - PEBA, - Polyureas, particularly aromatic polyureas, - Polymers and copolymers of the acrylic family, such as polyacrylates, more particularly polymethyl methacrylate (PMMA), or its derivatives, - Poly(aryl ether ketone) (PAEK), such as polymers or copolymers of the family like poly(ether ether ketone) (PEEK) or poly(aryl ether ketone ketone) (PAEKK), such as poly(ether ketone ketone) (PEKK) or its derivatives, - Aromatic polyetherimide (PEI), - Polyaryl sulfide, particularly polyphenylene sulfide (PPS), - Polyaryl sulfone, particularly polyphenylene sulfone (PPSU), - Polyolefins, particularly polypropylene (PP), - Polylactic acid (PLA), - Polyvinyl alcohol (PVA), - Fluoropolymers, especially poly(vinylidene fluoride) (PVDF) or polytetrafluoroethylene (PTFE) or polychlorotrifluoroethylene (PCTFE), - And mixtures thereof can be selected from. Advantageously, when the polymer is a mixture of two polymers P1 and P2, the weight ratio of polymer P1 to P2 is from 1 to 99% to 99 to 1%. Advantageously, when the thermoplastic polymer is a mixture and the pre-impregnation method uses dry powder, this mixture is in the form of a powder obtained either by dry mixing before charging into the pre-impregnation tank, or by dry mixing directly carried out in the tank, or by grinding a pre-compounded material previously carried out by an extruder. Advantageously, this mixture is composed of a powder obtained by "dry mixing" before charging into the tank or directly in the tank, and this mixture of two polymers P1 and P2 is a mixture of PEKK and PEI. Advantageously, the PEKK / PEI mixture is from 90 to 10 wt% to 60 to 40 wt%, especially from 90 to 10 wt% to 70 to 30 wt%. The thermoplastic polymer can correspond to a non-reactive final polymer that impregnates the fibrous material or a reactive prepolymer that also impregnates the fibrous material but reacts with itself or another prepolymer or a chain extender depending on the chain ends carried by the prepolymer after pre-impregnation, especially during heating at the level of the tensioning device in the furnace and / or during processing of the tape in the final process for manufacturing the composite part. The expression "non-reactive polymer" means that the molecular weight has no significant possibility of change, that is, when the polymer is processed and thus corresponds to the final polyamide polymer of the thermoplastic matrix, its number average molecular weight (Mn) changes by less than 50%. Conversely, the expression "reactive polymer" means that the molecular weight of the reactive polymer changes during processing by condensation or substitution of the reactive prepolymer with each other or reaction with a chain extender by polyaddition without removal of volatile by-products, resulting in the final polyamide polymer (non-reactive) of the thermoplastic matrix. According to a first possibility, the prepolymer may comprise or consist of at least one reactive prepolymer (polyamide) having two terminal functional groups X' and Y' on the same chain (i.e., on the same prepolymer) whose functional groups are co-reactive with each other by condensation, and more specifically, X' and Y' are each an amine and a carboxyl or a carboxyl and an amine. According to a second possibility, the prepolymer may comprise or consist of at least two polyamide prepolymers having two terminal functional groups X' or Y' that are reactive with each other and are each identical (identical for the same prepolymer and different between two prepolymers), and the functional group X' of one prepolymer can react only with the functional group Y' of the other prepolymer, particularly by condensation, and more specifically, X' and Y' are each an amine and a carboxyl or a carboxyl and an amine. According to a third possibility, the prepolymer is at least one prepolymer of the thermoplastic polyamide polymer having n reactive terminal functional groups X selected from -NH2, -CO2H and -OH, preferably NH2 and -CO2H, where n is from 1 to 3, preferably from 1 to 2, more preferably 1 or 2, and more specifically 2, and at least one chain extender Y-A'-Y, where A' is a hydrocarbon biradical, having two identical reactive terminal functional groups Y and being reactive with at least one functional group X of the prepolymer a1) by polyaddition and preferably having a molecular weight of less than 500, more preferably less than 400. The number average molecular weight Mn of the final polymer of the thermoplastic matrix is preferably in the range of 10,000 to 40,000, preferably 12,000 to 30,000. These Mn values are determined in m-cresol according to ISO standard 307:2007, except for changing the solvent (using m-cresol instead of sulfuric acid, temperature 20 °C), and can correspond to an intrinsic viscosity of 0.8 or more. The reactive prepolymer according to the above two options has a number average molecular weight Mn in the range of 500 to 10,000, preferably 1,000 to 6,800, particularly 2,500 to 6,800. Mn is determined in particular by the content of terminal functional groups determined by potentiometric titration in solution and by calculation based on the functionality of the prepolymer. The molecular weight Mn can also be determined by size exclusion chromatography or NMR. The nomenclature used to define polyamides is described in particular on page 3 (Tables 1 and 2) of ISO standard 1874-1:2011 "Plastics - Polyamide (PA) moulding and extrusion materials - Part 1: Designation" and is well known to those skilled in the art. The polyamide can be a homopolyamide or a copolyamide or a mixture thereof. Advantageously, the prepolymer constituting the matrix is selected from polyamides (PA), in particular aliphatic polyamides, alicyclic polyamides, and semi-aromatic polyamides (polyphthalamides) which may be modified with urea moieties and their copolymers, polymethyl methacrylate (PPMA) and their copolymers, polyetherimide (PEI), polyphenylene sulfide (PPS), polyphenylene sulfone (PPSU), PVDF, poly(ether ketone ketone) (PEKK), poly(ether ether ketone) (PEEK), fluoropolymers such as poly(vinylidene fluoride) (PVDF). In the case of fluoropolymers, a homopolymer of vinylidene fluoride (VDF of the formula CH2=CF2), or a copolymer of VDF containing at least 50% by weight of VDF and at least one other monomer copolymerizable with VDF can be used. The content of VDF should exceed 80% by weight, or more preferably be 90% by weight or more, in order to ensure good mechanical strength and chemical resistance in the structural parts, especially when exposed to heat and chemical stress. The comonomer can be a fluoromonomer such as vinyl fluoride. For structural parts that need to withstand high temperatures, in addition to fluoropolymers, PAEK (polyaryletherketone), such as poly(etherketone) (PEK), poly(etheretherketone) (PEKK), poly(etherketoneketone) (PEKK), poly(etherketoneetherketoneketone) (PEKEKK) or PA having a high glass transition temperature Tg are preferably used according to the present invention. Preferably, the thermoplastic polymer is a polymer having a glass transition temperature of Tg≧80°C, especially ≧100°C, particularly ≧120°C, especially ≧140°C, or a semi-crystalline polymer having a melting temperature Tm≧150°C. Preferably, the thermoplastic polymer of the matrix is a non-reactive thermoplastic polymer. Preferably, the at least one thermoplastic prepolymer is selected from polyamide, PEKK, PEI, and a mixture of PEKK and PEI. Preferably, the polyamide is selected from aliphatic polyamides, alicyclic polyamides, and semi-aromatic polyamides (polyphthalamides). Preferably, the aliphatic polyamide prepolymer is selected from the following: - Selected from polyamide 6 (PA6), polyamide 11 (PA11), polyamide 12 (PA12), polyamide 66 (PA66), polyamide 46 (PA46), polyamide 610 (PA610), polyamide 612 (PA612), polyamide 1010 (PA1010), polyamide 1012 (PA1012), polyamide 11 / 1010 and polyamide 12 / 1010, or mixtures or copolyamides thereof, and block copolymers, in particular polyamide / polyether (PEBA), wherein the semi-aromatic polyamide may be a semi-aromatic polyamide modified with a urea moiety, in particular PA MXD6 and PA MXD10, or a semi-aromatic polyamide of the formula X / YAr as described in EP1505099, in particular a semi-aromatic polyamide of the formula A / XT (wherein A is selected from a moiety derived from an amino acid, a moiety derived from a lactam, and a moiety corresponding to the formula (Ca diamine)·(Cb diacid), a represents the number of carbon atoms of the diamine, b represents the number of carbon atoms of the diacid, a and b are each between 4 and 36, preferably between 9 and 18, the (Ca diamine) moiety is selected from linear or branched aliphatic diamines, cycloaliphatic diamines, and alkyl aromatic diamines, and the (Cb diacid) moiety is selected from linear or branched aliphatic diacids, cycloaliphatic diacids, and aromatic diacids); X.T represents a moiety obtained by polycondensation of Cx diamine and terephthalic acid, x represents the number of carbon atoms of Cx diamine, x is between 6 and 36, preferably between 9 and 18, in particular polyamides of the formula A / 6T, A / 9T, A / 10T or A / 11T (wherein A is as defined above), in particular polyamides PA 6 / 6T, PA 66 / 6T, PA 6I / 6T, PA MPMDT / 6T, PA PA11 / 10T, PA 11 / 6T / 10T, PA MXDT / 10T, PA MPMDT / 10T, PA BACT / 10T, PA BACT / 6T, PA BACT / 10T / 6T, PA BACT / 10T / 11, PA BACT / 6T / 11. T corresponds to terephthalic acid, MXD corresponds to m-xylylenediamine, MPMD corresponds to methylpentamethylenediamine, and BAC corresponds to bis(aminomethyl)cyclohexane. Advantageously, the thermoplastic polymer is a semi-aromatic polyamide. Advantageously, the thermoplastic polymer is a semi-aromatic polyamide selected from PA MPMDT / 6T, PA PA11 / 10T, PA 11 / 6T / 10T, PA MXDT / 10T, PA MPMDT / 10T, PA BACT / 10T, PA BACT / 6T, PA BACT / 10T / 6T, PA BACT / 10T / 11, PA BACT / 6T / 11. [Regarding the pre-impregnation process] The pre-impregnation process as already shown above is carried out in a fluidized bed. Advantageously, the pre-impregnation is carried out in a fluidized bed and one or more tensioning devices (E) are present upstream of the system. The fluidized bed pre-impregnation process is described in WO2018 / 115736. An example of an apparatus for carrying out the manufacturing method without a heating step by at least one tensioning device is described in international application WO2015 / 121583. This system describes the use of a tank containing a fluidized bed for carrying out the pre-impregnation process and can be used within the context of the present invention. Advantageously, the tank containing the fluidized bed is provided with at least one tensioning device (E’) which can be a compression roller. It should be noted that the tensioning devices (E) and (E’) may be the same or different in terms of material or shape and its characteristics (such as diameter, length, width, height, etc. depending on the shape). However, the tensioning device (E’) is not a heating device and is not heated either. The process of pre-impregnating the fibrous material is carried out by passing one or more rovings through a continuous pre-impregnation device comprising a tank (20) provided with at least one tensioning device (E’) and having a fluidized bed (22) of the powder of the polymer matrix. The powder of the polymer matrix or polymer is introduced into the tank and suspended in a gas G (for example, air) flowing into the tank (20) through a hopper (21). The rovings are circulated through this fluidized bed (22). The tank can have any shape, in particular a cylinder or a parallelepiped, in particular a cuboid or a cube, and preferably a cuboid. The tank (20) can be an open or closed tank. Preferably, the tank is open. In the case of a closed tank, the tank is provided with a sealing system so that the powder of the polymer matrix does not come out of the tank. Therefore, this pre-impregnation step is carried out by a drying path, that is, the thermoplastic polymer matrix is in the form of a powder suspended in a gas, in particular air, but cannot be dispersed in a solvent or water. Each rovings pre-impregnated after passing through the tensioning device (E) enters the tank (20). Next, the fiber rovings or parallel fiber rovings enter the tank (20) particularly including a fluidized bed (22) with at least one tensioning device (E') already present in the tank or which is a compression roller, and then enter the fluidized bed (22) with at least one tensioning device (E') attached. Next, the fiber rovings or parallel fiber rovings come out of the tank after pre-impregnation, optionally controlling the residence time in the powder.

[0155] In one embodiment, the method according to the invention includes a step of heating the pre-impregnated fibrous material to melt the thermoplastic polymer of the matrix and finalize the impregnation of the fibrous material. The heating step can be carried out as described in WO2018 / 234439. The first heating step can follow immediately after the pre-impregnation step, or otherwise, other steps can occur between the pre-impregnation step and the heating step. Preferably, the first heating step follows immediately after the pre-impregnation step. The expression "follows immediately after" means that there is no intermediate step between the pre-impregnation step and the heating step. Preferably, a single heating step is carried out immediately after the pre-impregnation step. Preferably, the at least one heating system is selected from infrared lamps, UV lamps, and convective heating. The fibrous material is in contact with a tension device in the heating system, and since the tension device is conductive, therefore, the heating system is also carried out by conduction. Advantageously, the at least one heating system is selected from infrared lamps. Advantageously, the at least one tension device (E'') is a convex, concave, or cylindrical compression roller. The compression rollers corresponding to the tension devices (E), (E'), and (E'') can be the same or different in terms of material or shape and its characteristics (diameter, length, width, height, etc. according to the shape). Convex is preferable for stretching, and concave is disadvantageous for stretching, but it is still implemented. The at least one tension device (E'') can also have a shape that alternates between convex and concave. In that case, when the roving runs on the convex compression roller, the roving causes stretching, and then when the roving runs on the concave compression roller, contraction of the roving occurs, etc., and it is possible to improve the uniformity of impregnation into the core, particularly as required. The expression "compression roller" means that the running roving presses partially or completely on the surface of the compression roller, which induces stretching of the roving. The roller can be of the free (rotating) type or the fixed type. The roller can be smooth, ribbed, or grooved. Advantageously, the roller is cylindrical and ribbed. When the roller is ribbed, two ribs can start from the center of the roller and exist in opposite directions from each other. Therefore, the roving can be moved outward from the roller or start from the outside of the roller and move in opposite directions from each other, and the lock can be directed towards the center of the roller. This heating process makes the pre-impregnation uniform, thus completing the impregnation and thus performing core impregnation, resulting in a high content of fibers by volume, in particular strips or ribbons with a constant content of at least 70% by volume, especially strips or ribbons with at least 80% by volume, in particular strips or ribbons with at least 90% by volume, more specifically strips or ribbons with at least 95% by volume, and also making it possible to reduce the porosity. The draw depends on the fibrous material used. For example, the draw of a carbon fiber material is much greater than that of a flax fiber. The draw also depends on the number of fibers in the roving, their average diameter, and their aggregation by size. The diameter of the at least one compression roller (tension device (E’’)) is from 3 mm to 100 mm, preferably from 3 mm to 20 mm, in particular from 5 mm to 10 mm. If it is less than 3 mm, the deformation of the fibers caused by the compression roller is too large. Advantageously, the compression roller is cylindrical and without grooves, in particular made of metal. Advantageously, the at least one tension device (E’’) consists of at least one cylindrical compression roller. Advantageously, the at least one tension device (E’’) consists of from 1 to 15 cylindrical compression rollers (R1 to R15), preferably from 3 to 15 compression rollers (R3 to R15), in particular from 6 to 10 compression rollers (R6 to R10). Regardless of the number of tension devices (E’’) present, it is quite clear that they are all arranged or contained in the environment of the heating system, i.e., they are not outside the heating system.

[0156] According to another aspect, the present invention relates to the use of the method described above for manufacturing a calibration ribbon suitable for manufacturing three-dimensional composite parts by automatic layup of the calibration ribbon using a robot.

[0157] Advantageously, the composite part relates to the fields of transport, in particular automotive transport, oil and gas, in particular offshore, hydrogen, gas storage, in particular hydrogen, aviation, naval and rail transport; renewable energy, in particular wind turbines or tidal turbines, energy storage devices, solar panels; insulation panels; sports and leisure, health and medicine, and electronics.

[0158] According to another aspect, the invention relates to a three-dimensional composite part, characterized in that it is obtained from the use of the method described above.

[0159] According to yet another aspect, the invention relates to a tank (20) comprising a fluidized bed (22), a scraper or a lateral suction system for sucking fine particles, for use in the method described above.

[0160] According to yet another aspect, the invention relates to a tank (20) comprising a fluidized bed (22), a scraper, and a lateral suction system for sucking fine particles, for use in the method described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0161]

Figure 1

[0162]

Figure 2

[0163]

Figure 3

[0164]

Figure 4

[0165]

Figure 5

[0166]

Figure 6

[0167]

Figure 7

Example

[0168] Example 1 The manufacturing test was carried out in a transparent parallelepiped tank with dimensions L×l×h = 500×500×400 mm 3 on a pilot line for pre-impregnating the 12k fibrous material AS4 made by Hexcel with a BACT / 10T thermoplastic polymer matrix having a particle size of D50 = 106 μm. As the pre-impregnation progressed, only the powder was added manually. The added powder had the same particle size as that in the tank at the start. Therefore, this situation is the worst scenario with no control or readjustment regarding the particle size. Four types of powder were obtained whose particle size could be analyzed: - Those carried away by the fibrous material and whose particle size distribution is substantially equivalent to that present in the tank → G0 - Those that scatter and fall next to the tank, and those that are carried away by the fibrous material and fall from the fibrous material before melting → G1 - Those that are initially present in the tank → G2 - Those that are present in the tank at the end of manufacturing → G3 After one week of manufacturing, the volume of the powder with particle size G1 found next to the tank was measured to be equal to 1 / 20 of the volume of the powder that was initially present in the tank. After one week of manufacturing, the following table is obtained:

Table 1

[0169] Example 2 A tank equipped with an automatic scraper and an automatic system for supplying powder during manufacturing Fibrous material: Carbon fiber AS4 12k made by Hexcel Thermoplastic polymer: BACT / 10T (40 / 60 mole percent) with a Tg of 140 °C and a particle size D50 = 106 μm. Using the scraper, rake treatment is carried out every 15 minutes, thereby returning to the initial bed height, and without adding powder, the amount of BACT / 10T being carried can be maintained for 1 hour and 40 minutes, so that the generated fluff accumulating on the surface of the frit can be recovered. The results are shown in Figure 7.

Claims

1. A method for manufacturing an impregnated fibrous material comprising at least one fibrous material made of continuous fibers and at least one thermoplastic polymer matrix, the method comprising a step of pre-impregnating the fibrous material with the thermoplastic polymer matrix in powder form, wherein the pre-impregnation step is carried out dry in a tank (20) comprising a fluidized bed (22), and the pre-impregnation step is carried out while substantially maintaining a constant level h of the powder present in the tank (20) and a mass m of the powder, the level h being from h ｉ to h ｉ −3%, where h ｉ is the initial level of the powder in the tank (20) at the start of the pre-impregnation step, and the mass m is from m ｉ to m ｉ ±0.5% during the pre-impregnation step, where m ｉ is the initial mass of the powder in the tank (20) at the start of the pre-impregnation step, excluding electrostatic processes involving intentional charging, and The particle size of the powder is substantially constant in the tank (20), i.e., the maximum variation in D50 is +20%. A method, characterized by this.

2. The method according to claim 1, characterized in that the volume average particle size D50 of the thermoplastic polymer powder particles is from 30 to 300 μm.

3. The method according to claim 1 or 2, characterized in that a thermoplastic polymer matrix in powder form is supplied to the tank (20) to compensate for the consumption of the thermoplastic polymer matrix by the preliminary impregnation of the fibrous material.

4. The method according to any one of claims 1 to 3, characterized in that the particle size of the fine particles of the powder is substantially constant in the tank (20), i.e., the maximum variation in D10 is +30%.

5. The method according to any one of claims 1 to 4, characterized in that the particle size of the large particles of the powder is substantially constant in the tank (20), i.e., the maximum variation in D90 is +10%.

6. The method according to any one of claims 1 to 3, characterized in that the particle size of the fine particles of the powder is substantially constant in the tank (20), i.e., the maximum variation in D10 is +30%, and the particle size of the large particles of the powder is substantially constant in the tank (20), i.e., the maximum variation in D90 is +10%.

7. The method according to any one of claims 1 to 6, characterized in that the tank (20) includes a fluidized bed (22), and the preliminary impregnation step is carried out with rolling (81a) or simultaneous extension of a group of rollings between the inlet and the outlet of the fluidized bed (22).

8. The method according to any one of claims 1 to 7, characterized in that the tank (20) is provided with a scraper. Level h < h ｉ The method according to claim 8, characterized in that the scraper is automatically used when it is -3%.

9.

10. The method according to any one of claims 1 to 9, characterized in that the tank (20) is provided with a lateral suction system for sucking fine particles with a particle size of 0.01 to 60 μm that exit the tank (20) during fluidization.

11. The method according to claim 10, characterized in that the sucked particles are continuously recharged into the tank (20).

12. The method according to any one of claims 1 to 11, characterized in that the tank (20) is provided with a scraper and a lateral suction system for sucking fine particles having a particle size of 0.01 to 60 μm exiting the tank (20).

13. The method according to any one of claims 1 to 12, characterized in that the fluidized bed (22) includes at least one tension device (82), and the roving (81a) or the group of rovings is in contact with a part or the whole of the surface of the at least one tension device (82).

14. The method according to any one of claims 1 to 13, characterized in that the thermoplastic polymer is a non-reactive thermoplastic polymer.

15. The method according to claim 14, comprising the step of heating a pre-impregnated fibrous material to melt the thermoplastic polymer and finalizing the impregnation of the fibrous material.

16. The method according to any one of claims 1 to 13, characterized in that the thermoplastic polymer is a reactive prepolymer and can react with itself or another prepolymer or a chain extender depending on the chain ends carried by the prepolymer.

17. The method according to claim 16, comprising the step of heating a pre-impregnated fibrous material to melt the thermoplastic prepolymer, optionally polymerizing with the extender, and finalizing the impregnation of the fibrous material.

18. Use of the method according to any one of claims 1 to 17 for manufacturing a calibration ribbon suitable for manufacturing three-dimensional composite parts by automatic laying-up of the calibration ribbon using a robot.

19. A three-dimensional composite part, characterized in that it is obtained from the use of the method according to claim 18.

20. A tank (20) comprising a fluidized bed (22) and a scraper or a lateral suction system for sucking fine particles, for use in the method according to any one of claims 1 to 17.

21. A tank (20) comprising a fluidized bed (22), a scraper, and a lateral suction system for sucking fine particles, for use in the method according to any one of claims 1 to 17.

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