FR2949793A1 - PROCESS FOR PRODUCING A THERMOPLASTIC OR THERMOSETTING POLYMER PRE-IMPREGNATED FIBROUS MATERIAL AND SYSTEM THEREOF - Google Patents

Abstract

The invention relates to a method of manufacturing a fibrous material such as a nonwoven fabric, felt, which may be in the form of strips, webs, braids, locks or pieces, based on reinforcing fibers and polymer. The invention also relates to a system for implementing the method. According to the invention at least two sets of different fibers are used, a first series of fibers comprising reinforcing fibers, for example mineral fibers, and a second series of fibers comprising organic polymer fibers (thermoplastic or thermosetting) having a melting point T f the two series of fibers are placed in contact with each other and then the whole of the two series of fibers are heated to a temperature at least equal to the melting temperature Tf of the fibers of the second series, and then the whole is allowed to cool to room temperature. The invention applies to the manufacture of 3D parts.

Description

PROCESS FOR MANUFACTURING A THERMOPLASTIC OR THERMOSETTING POLYMER PREMIXED FIBROUS MATERIAL AND SYSTEM FOR CARRYING OUT SAID METHOD

FIELD OF THE INVENTION The present invention relates to a method for manufacturing a fibrous material, such as a nonwoven fabric, felt, which may be in the form of strips, sheets, braids, locks or pieces, based on reinforcement and organic polymer namely thermoplastic polymer or thermosetting and an implementation system. The fibers that can be used in the composition of the material are more particularly carbon fibers, glass fibers, polymer-based fibers, vegetable fibers, used alone or as a mixture. Of interest in the present invention are lightweight composite materials for the manufacture of mechanical parts having a 3-dimensional structure and having properties of good mechanical strength, thermal and able to evacuate electrostatic charges, that is to say to say properties compatible with the manufacture of parts in the field of mechanics, aeronautics and nautical.

STATE OF THE ART It is known to use refractory fabrics pre-impregnated with a resin in order to produce a thermally insulating matrix so as to provide thermal protection for mechanical devices subjected to high temperatures, as may be the case in the field. aeronautics or the automobile. Reference can be made to European Patent No. 0 398 787, which describes a thermal protection layer comprising a refractory fabric intended to protect the ferrule of a ramjet engine chamber. In addition to the complexity of producing this thermal protection layer, the refractory fabric embedded in this layer only fulfills the function of heat shield.

In recent years, composite fibers have also been used to manufacture, in particular, various aeronautical or automobile parts. These composite fibers, which are characterized by good thermomechanical and chemical resistance, consist of a reinforcing filament reinforcement intended to distribute the tensile, flexural or compressive tensile forces, in some cases to provide protection chemical material and give it its shape. Ref: 0276B -ARK14 One can for example refer to the patent application FR 2 918 081 which describes a process for impregnating continuous fibers with a composite polymeric matrix containing a thermoplastic polymer. Methods for manufacturing composite parts from these coated fibers include various techniques such as, for example, contact molding, spray molding, autoclaved draping or low pressure molding. A technique for making hollow parts is that called filament winding, which consists in impregnating dry fibers with a resin and then winding them on a mandrel formed of reinforcements and of a shape adapted to the part to be manufactured. The piece obtained by winding is then cured by heating. Another technique for making plates or shells consists in impregnating fiber fabrics and then pressing them into a mold in order to consolidate the laminated composite obtained.

For the manufacture of polymeric material with fiber reinforcement, a sizing step is generally used, which consists in depositing a thermoplastic polymer film on fibers. Thus, the process for manufacturing preimpregnated material from Cyntex comprises, as a fiber coating step, the continuous passage of fibers in a molten bath of thermoplastic polymer containing an organic solvent such as benzophenone; this solvent makes it possible to adapt the viscosity of the melted mixture and to ensure a good coating of the fibers. The pre-impregnated fibers of polymers are then shaped (for example cut into strips and then placed under a press, for producing the structural parts, and then heated to a temperature above the melting temperature of the polymer to ensure the cohesion of the polymer. material and in particular the adhesion of the polymer to the fibers.

The technical problem Depending on the chemical nature of the polymer, the heating temperatures can rise to temperatures above 250 ° C, and even higher than 320 ° C, temperatures much higher than the boiling temperature of the solvent, resulting in a sudden departure of solvent, causing defects in the room and therefore a lack of reproducibility of the process as well as the risk of explosion endangering the operators. Ref: 0276B -ARK14 Another known fiber sizing process is the continuous passage of the fibers in an aqueous dispersion of polymeric powder and then drying the fibers to evaporate the water in an oven, followed by a heat treatment for the fusion of the polymer. This heat treatment can be done in a shaping die, especially to make strips of pre-impregnated material. These strips are then used for the manufacture of structural parts, by arrangement in a mold, a press, etc. This process requires two separate heating zones or the use of two separate furnaces is complex and difficult to implement.

As another state of the art relating to the manufacture of a fibrous material, reference may be made to document US Pat. No. 4 541884 from Imperial Chemical Industries or to document EP 0406 067 filed in the joint names of Atochem and the State. French. As prior art relating to the introduction of fibers for the formation of fibrous material and the constitution of structures based on this fibrous material, reference may be made to US Pat. No. 6,607,626; US Pat. No. 6,939,424 and US Pat. No. 7,235,149. SUMMARY OF THE INVENTION The subject of the invention is a new process for the on-line and continuous manufacture of fibrous material, making it possible to overcome the above disadvantages. The proposed method also makes it possible to obtain a homogeneous fibrous material. There can be no irregularities in the structure or node susceptible to embrittle the material with risks of rupture as is the case with the methods of the prior art. More specifically, the subject of the invention is a process for producing a fibrous material pre-impregnated with an organic polymer consisting of i) using at least two sets of different fibers, a first series of fibers comprising reinforcing fibers and a second series of fibers comprising organic polymer fibers having a melting temperature Tf, ii) arranging the two series of fibers in contact with each other and then iii) heating all of the two sets of fibers to one temperature at least equal to the melting temperature Tf of the organic fibers and to allow the whole to cool to room temperature. Ref: 0276B -ARK14 The reinforcing fibers constituting the first series may be mineral fibers or organic fibers of thermoplastic or thermosetting polymer or else mineral fibers and organic fibers of thermoplastic or thermosetting polymer.

The organic fibers constituting the fibers of the second series are made of thermoplastic or thermosetting polymer. In all cases, that is to say, whatever the composition of the fibers of the first or second series, the melting temperature Tf of the fibers of the second series is always less than the melting temperature of the fibers of the second series. first series so that the heating step causes the melting of the fibers of the second series, the latter then impregnating the fibers of the first series constituting reinforcing fibers of the fibrous material thus obtained. The polymers used in the constitution of thermosetting fibers are chosen from: unsaturated polyesters, epoxy resins, vinyl esters, phenolic resins, polyurethanes, cyanoacrylates and polyimides, such as bis-maleimide resins, aminoplasts (resulting reaction of an amine such as melamine with an aldehyde such as glyoxal or formaldehyde) and mixtures thereof.

By thermosetting polymers or thermosetting resins is meant a generally liquid material at room temperature, or low melting point, which is capable of being cured, generally in the presence of a hardener, under the effect of heat, d A catalyst, or a combination of both, to obtain a thermoset resin This is made of a material containing polymeric chains of variable length interconnected by covalent bonds, so as to form a three-dimensional network. In terms of its properties, this thermoset resin is infusible and insoluble. It can be softened by heating it above its glass transition temperature (Tg) but, once a shape has been imparted to it, it can not be reshaped later by heating. The thermosetting polymers (or resins) forming part of the thermosetting fibers according to the invention are chosen from: unsaturated polyesters, epoxy resins, vinyl esters, phenolic resins, polyurethanes, cyanoacrylates and polyimides, such as bis-maleimide resins, aminoplasts (resulting from the reaction of a Ref: 0276B-ARK14 amine such as melamine with an aldehyde such as glyoxal or formaldehyde) and mixtures thereof. The unsaturated polyesters result from the condensation polymerization of dicarboxylic acids containing an unsaturated compound (such as maleic anhydride or fumaric acid) and glycols such as propylene glycol. They are generally hardened by dilution in a reactive monomer, such as styrene, and then reaction of the latter with the unsaturations present on these polyesters, generally with the aid of peroxides or a catalyst, in the presence of heavy metal salts or an amine, or using a photoinitiator, ionizing radiation, or a combination of these different techniques. The vinyl esters include the products of the reaction of epoxides with (meth) acrylic acid. They can be cured after dissolution in styrene (similar to polyester resins) or with the aid of organic peroxides. The epoxy resins consist of materials containing one or more oxirane groups, for example from 2 to 4 oxirane functions per molecule. In the case where they are polyfunctional, these resins may consist of linear polymers bearing epoxy end groups, or whose backbone comprises epoxy groups, or whose skeleton carries pendant epoxy groups. They generally require as curing agent an acid anhydride or an amine. These epoxy resins may result from the reaction of epichlorohydrin with a bisphenol such as bisphenol A. It may alternatively be alkyl- and / or alkenylglycidyl ethers or esters; polyglycidyl ethers of optionally substituted mono- and polyphenols, especially polyglycidyl ethers of bisphenol A; polyglycidyl polyol ethers; polyglycidyl ethers of aliphatic or aromatic polycarboxylic acids; polyglycidyl esters of polycarboxylic acids; Alternatively, it may be products of the reaction of epichlorohydrin with aromatic amines or glycidyl derivatives of mono- or aromatic diamines. Cycloaliphatic epoxides and preferably diglycidyl ethers of bisphenol A (or DGEBA), F or NF can also be used in the present invention. Among the hardeners or crosslinking agents, it is possible to use di-amine or tri-amine functional products used. at levels ranging from 1 to 5%. Ref: 0276B -ARK14 For heating temperatures of thermosetting fibers we speak of melting or softening temperatures, they are of the order of 50 ° C to 80 ° C, typically 60 ° C. After adding a hardener (or crosslinking agent), the melting or softening temperature is then brought between 100 ° C. and 150 ° C., typically 120 ° C. The heating at the melting temperature Tf is associated with a shaping of all the two sets of fibers, the thermosetting polymer fibers may be shaped in an apparatus normally used for a thermoplastic polymer such as a twin extruder. -vis or a co-mixer. According to the invention, the heating of the two sets of reinforcing fibers (mineral and / or organic) and of polymer can be achieved by laser heating or a plasma torch, nitrogen or an infrared oven or microwave or induction.

Preferably, step iii) of heating will be performed by induction or microwaves in the presence of electrically conductive fibers in the assembly or electrically conductive fillers in the preimpregnated material. The conductivity properties of the preimpregnated material are advantageous in combination with induction or microwave heating, since the electrical conductivity is then used and contributes to obtaining a core firing and a better homogeneity of the material. fibrous material. The thermal conduction of the fibers of the assembly or of the fillers present in the preimpregnated fibrous material also contributes, with this type of heating, to core firing improving the homogeneity of the material.

The fillers used are, for example, metal powder, powdery carbon black, carbon fibrils, carbon nanotubes, or nanotubes of silicon carbide, boron carbonitride, boron nitride or silicon. Preferably, the charges used are conducting electricity and / or heat, such as carbon nanotubes, carbon fibrils or even carbon black. Preferably, carbon nanotubes are used. It is recalled that carbon nanotubes NTC means one or more hollow tubes with one or more graphitic plane walls or graphene sheets, coaxial, or graphene sheet wound on itself. This or these tubes, most often opening (that is to say open at one end) resemble several Ref: 0276B -ARK14 grid tubes arranged coaxially; in cross section the CNTs are in the form of concentric rings. The external diameter of the CNT is from 2 to 50 nm. We speak of single-walled carbon nanotubes (SWNTs) or multi-walled carbon nanotubes (MWNTs). Thus, the heating by microwave or induction is particularly well suited in the presence of fillers such as carbon nanotubes NTC in the preimpregnated material because we then obtain a better dispersion / distribution of CNTs within the material, leading to a better homogeneity of the physico-chemical properties, and consequently better overall properties on the final product. Of course, when the heating is performed by induction, a conductive material is used. In the absence of conductive fibers in the assembly or conductive fillers in the preimpregnated fibrous material, this material may be in contact with the fiber assembly such as for example the fiber support on which they are laid for cooking. . For the introduction of conductive fillers, the procedure is as follows: - on the assembly of the two series of fibers, just before the heating step iii), mineral fillers in the form of a powder, which are conductive, such as metal powder, powdery carbon black, carbon fibrils, carbon nanotubes, or as nanotubes of silicon carbide, boron carbonitride, boron nitride or silicon. When the assembly of the two sets of fibers comprises thermosetting fibers, carbon nanotubes powder will be placed on this assembly before introducing a hardener. An induction or microwave heating is preferable, especially in the presence of electrically conductive fibers in the assembly or in the presence of electrically conductive fillers in the pre-impregnated material to promote core heating. The dusting of the loads can be ensured by means of a vibrating support, in order to ensure a homogeneous distribution on the fibers. For example, the CNT powder is deposited directly on the fibrous material, placed flat on a vibrating support, in order to allow the distribution of the powder on the fibers.

Before the dispersion of the charges on the two sets of fibers, these fillers can be subjected to a chemical treatment in order to provide them with functions such as polar ones to improve their adhesion to the polymeric fibers or else subjected to a heat treatment, for example greater than 900 ° C and better at 1000 ° C to remove metal impurities due to their synthesis process.

Advantageously, the charges are neither chemically nor thermally treated. In the case of thermoplastic fibers, these fibers may consist of a single type of polymer or of several polymers; in the case of several polymers, the melting temperature Tf above is that of the highest melting temperature polymer. The polymers used in the constitution of the fibers of the second series of fibers may be chosen, without limitation, from: polyethylenimines (PEI), polyimides (PI), polyolefins such as polyethylene, especially high density polypropylene and copolymers of ethylene and / or polypropylene; thermoplastic polyurethanes (TPU); polyesters such as polyhydroxyalkanoates; polyethylene terephthalates (PET) or butylene (PBT); polyphenylene sulfides (PPS); polyvinyl chlorides; silicone or fluorosilicone polymers; poly (vinyl alcohol); polyarylether ketones (PAEK: PolyArylEtherKetone) such as polyetheretherketone (PEEK) and polyetherketoneketone (PEKK); polyamides such as polyamide such as polyamide 6 (PA-6), polyamide 11 (PA-11), polyamide 12 (PA-12), polyamide 6.6 (PA-6.6), polyamide 4.6 (PA-6), 4.6), polyamide 6.10 (PA-6.10), polyamide 6.12 (PA-6.12), aromatic polyamides, in particular polyphthalamides and aramid, and block copolymers, in particular polyamide / polyether; the fluorinated polymers comprising at least one monomer of formula (I): CFX = CHX '(I) where X and X' independently denote a hydrogen or halogen atom (in particular fluorine or chlorine) or a radical perhalogenated (in particular perfluorinated) alkyl, and preferably X = F and X '= H, such as polyvinylidene fluoride (PVDF), preferably in the α form, vinylidene fluoride copolymers with, for example

Ref: 0276B-ARK14 hexafluoropropylene (HFP), fluoroethylene / propylene copolymers (FEP), copolymers of ethylene with either fluoroethylene / propylene (FEP), tetrafluoroethylene (TFE) or perfluoromethylvinyl ether (PMVE) or chlorotrifluoroethylene (CTFE), some of these polymers being sold especially by Arkema under the name Kynar; polymers (or resins) phenoxy, and - their mixture.

Phenoxy polymers (or resins) which are polyhydroxy ethers terminated by alpha-glycol groups. They result from the reaction between bisphenol A and epichlorohydrin; their weight average molecular weight is from 25,000 to 60,000. They are compatible with thermosetting resins of the epoxy resin type.

For the fluoropolymers, it is preferred to use a homopolymer of vinylidene fluoride (VDF of formula CH2 = CF2) or copolymer of VDF comprising by weight at least 50% by weight of VDF and at least one other monomer copolymerizable with VDF. The VDF content must be greater than 80% by weight, or even better 90% by weight, to ensure good mechanical strength to the structural part, especially when subjected to thermal stresses. The comonomer may be a fluorinated monomer chosen, for example, from vinyl fluoride; trifluoroethylene (VF3); chlorotrifluoroethylene (CTFE); 1,2-difluoroethylene; tetrafluoroethylene (TFE); ethylene tetrafluoroethylene (ETFE), hexafluoropropylene (HFP); perfluoro (alkyl vinyl) ethers such as perfluoro (methyl vinyl) ether (PMVE), perfluoro (ethyl vinyl) ether (PEVE) and perfluoro (propyl vinyl) ether (PPVE); perfluoro (1,3-dioxole); perfluoro (2,2-dimethyl-1,3-dioxole) (PDD). Preferably, the optional comonomer is chosen from chlorotrifluoroethylene (CTFE), hexafluoropropylene (HFP), trifluoroethylene (VF3) and tetrafluoroethylene (TFE). The comonomer may also be an olefin such as ethylene or propylene. The preferred comonomer is HFP. For structural parts that must withstand high temperatures, in addition to the fluorinated polymers, PAEK (PolyArylEtherKetone) such as PEK, PEEK, PEKK, PEKEKK, etc. are advantageously used according to the invention. Compared to the processes of the prior art, the process according to the present invention is perfectly well suited to polymers Ref: 0276B-ARK14 having high melting temperatures, for example greater than 130 ° C, such as fluoropolymers, PAEKs high density polyethylenes, or else PET or PBT or PBT. It is also possible to use Kevlar fibers or aramid fibers.

The mineral fibers to which the invention applies are in particular the fibers of carbon, glass, boron, silica, natural fibers such as flax, especially silk spider, hemp, sisal. These fibers can be used pure, treated or coated with an induction layer, in order to facilitate the adhesion / impregnation of the thermoplastic polymer fibers of the second series or their handling before impregnation by melting of this polymer. Organic fibers may be blended with the mineral fibers to form the first series of fibers which is to be impregnated with polymer after melting the thermoplastic or thermosetting polymer fibers of the second series. In this case we will choose of course organic fibers that is to say polymer fibers whose melting temperature is higher than the melting temperature Tf fibers of the second series that one melts. Thus, there is no risk of fusion for the organic fibers present in the first series of fibers.

The fibrous material produced with the process is advantageously obtained with 50% of mineral fibers and 50% of thermoplastic or thermosetting organic polymer fibers, preferably with 30% of mineral fibers and 70% of thermoplastic or thermosetting organic polymer fibers.

The invention also relates to the use of fibrous material as described for the manufacture of mechanical parts in 3D, in particular the wings of an airplane, the fuselage of an airplane, the hull of a boat, the spars or spoilers of an automobile, or brake discs, or the cylinder body or steering wheels.

The invention is implemented by a system which comprises a device for placing the fibers in such a way as to arrange the two series of fibers in contact with each other and a device for heating the two sets of fibers made by a laser or plasma torch, nitrogen or an infrared oven or microwave or induction.

The induction heating device is obtained by exposing the fibers of the assembly to an alternating electromagnetic field by means of a high frequency unit from 650 KHz to 1 MHz for example. Ref: 0276B -ARK14 The microwave heating device is obtained by exposing the fibers of the assembly to a microwave electromagnetic field by means of a microwave generator of 2 to 3 GHz for example. The implementation system may comprise a calendering device. It can also be provided that the heating is carried out by the calendering device. The implementation system of the method advantageously makes it possible to shape the two sets of fibers, for example, in the form of a strip or sheet, or a strip which is cut to the desired length.

Preferably, the system for carrying out the method comprises a continuous formation line of said material in the form of a calibrated and homogeneous band of reinforcing fibers, for example mineral, impregnated with organic polymer, for example thermoplastic or thermosetting polymer. The continuous training line comprises a device for setting up the two series of fibers provided with a first calendering device. The placing device also comprises a preheating device for attenuating or reducing the temperature differences caused by the inertia of different types of fibers during heating at the melting temperature Tf. The placing device can also ensure the shaping of the material. However, the continuous forming line comprises, for this purpose, a shaping device implementing at least one calendering operation by means of a second calendering device and, preferably at least two successive calendering operations to obtain a material fibrous impregnated calibrated in a desired and homogeneous manner, that is to say without defect and without air bubble. For this, a third calendering device may be placed at the outlet of the second calendering device. The shaping device comprises a heating device for heating the two series of fibers to a temperature at least equal to the melting temperature Tf. In order to carry out the shaping in calibrated and continuous strip, each calendering device is notably provided with two cylinders, one of which has a male element ring, the other a flat-section female element groove of a determined width so that the fibers leaving the preheating device, are shaped in the groove by pressing the male element during their passage over the cylinder provided with the female element. Ref: 0276B -ARK14 Of course to ensure the shaping and proper operation of the training line, each calendering device comprises a synchronous drive motor of the two cylinders and a cylinder heating system.

To obtain the melting temperature Tf of the polymer fibers, the shaping device comprises a heating device placed between the first and the second calendering device. The device for placing the fibers also comprises, at the line inlet, a continuous unwinding station of the two series of fibers followed by the preheating device. For this purpose, the unwinding station of the fibers is advantageously provided with coils with horizontal unwinding axis. When the melting temperature Tf is high, preferably when it is greater than 200 ° C., as is the case, for example, for PAEK or PEEK fibers, it is intended to insert into the continuous training line, at the outlet of the shaping device, a cooling device. To allow easy packaging of the fibrous material web obtained, the continuous forming line advantageously comprises a winding device at the outlet of the cooling device.

The preheating or heating device are advantageously made by microwave heating units or by induction in particular in the presence of conductive fillers to promote heating core fibers. It may also be provided that the heating device and the preheating device each consist of two half-ovens with horizontal opening with infrared lamps and adjustable temperature. At least one of the half-furnaces comprises a calibrated flat bottom groove on which the fibers side by side of the two sets of fibers rest. All of the electrically or electronically controlled elements 30 are advantageously controlled and synchronized by a computer-type control station. Other features and advantages of the invention will become clear from reading the description which is given below and which is given by way of illustrative and nonlimiting example and with reference to the figures in which: FIG. the diagram of a first implementation system of the method according to the invention, Ref: 0276B-ARK14 - Figure 2 shows the diagram of a second implementation system of the method according to the invention, - Figure 3 represents the cross-sectional diagram AA of a fiber-coated support 50 according to the process; - FIG. 4 shows the cross-sectional diagram BB of the support 50 after melting of the thermoplastic polymer fibers according to the process; FIG. a third system for implementing the method. FIG. 6 represents the diagram of a third implementation system of the method according to the invention. - Figure 7 shows the diagram of a half-oven with the groove of placing fibers. - Figure 8 shows the schematic of calendering rolls with the complementary elements of calibration and shaping of the strip-shaped material.

The reinforcing fibers constituting the first series of fibers may be mineral fibers or thermoplastic fibers or thermosetting fibers or mineral fibers with thermoplastic fibers or with thermosetting fibers. The fibers of the second series intended to be melted to form the preimpregnated fibrous material are organic fibers made of thermoplastic or thermosetting polymer. Whatever the assembly made, the melting temperature of the second series of fibers is lower than that of the first series so that the preheating or heating steps do not change the fiber structure of the first series and that the fibers of the second series melt. For example, fibers of thermosetting resins may constitute the second series of fibers (epoxy polymers (without crosslinking) at a melting point of 60 ° C.) whereas the first series could be thermoplastic fibers of higher melting point (example a homopolyamide at a melting temperature of the order of 90 ° C or a polyvinylidene (PVDF) with a melting point of about 130 ° C. The first series could also be mineral fibers made of glass, silica, carbon, silicon carbide or metal carbide It is also possible to use two sets of thermosetting polymer fibers with different melting temperatures Ref: 0276B-ARK14 The systems shown in FIGS. of the in-line and continuous manufacturing process proposed according to the invention for the manufacture of fibrous material pre-impregnated with thermoplastic polymer or thermosetting.

Each system comprises a device 100 for setting up the two series of fibers, namely the first series of fibers 1 which comprises, for example, mineral fibers and the second series of fibers 2 which comprises, for example, thermoplastic polymer fibers having their temperature of fusion equal to Tf.

These devices have the same reference 100 in Figures 1, 2 and 5 and provide the same function namely to have the two sets of fibers in contact with one another. Each system also comprises a heating device 110 and possibly a calendering device 115 as is the case for the systems of FIGS. 1 and 5. It may be provided that the calendering device performs the heating function of two sets of fibers. . In the example of the system shown in Figure 1, the device 100 for placing fibers has two superimposed paths. The two series of fibers are brought by the two superimposed paths towards the same direction, these two paths approaching until the two sets of fibers are intercalated to form a homogeneous plane imposed by the size of the fibers, the fibers having constant dimensions. The homogeneous plane is in the form of a strip conveyed so as to pass in front of the heating device 110. This heating device makes it possible, in a few seconds, to reach the desired melting temperature Tf so that the thermoplastic polymer fibers having a melting temperature less than or equal to Tf, melt. The molten polymer adheres to the fibers of the first series (comprising, in the example, mineral fibers). After passage to ambient temperature, the strip of fibrous material 10 thus produced can be used as required, for example, be cut by a cutting device 200 to enter the manufacture of mechanical parts. Figure 2 shows a device adapted to the establishment of two sets of fibers on a support 50 serving as a mold to form the structure of a 3D piece of fibrous material. In this example, the device for placing the fibers consists of two arms 102 and 103 disposed above a horizontal plane driven by a mechanical system (not represented as a conveyor belt 101).

Ref: 0276B -ARK14 supports 50 are arranged on this carpet one behind the other following the without advancement. The arm 102 makes it possible to place the fibers of the first series 1 on a support 50 while the arm 103 makes it possible to place the fibers of the second series 2 on a support 50 on which the fibers of the first series have been put in place. Of course, the arms 102 and 103 are motorized so that they can be moved closer to the surface of the supports 50 in order to have a good accuracy in setting up the fibers. For the net stop of the fibers at the edges of the supports 50, the system may comprise cutting arms. When the supports 50 comprise the two sets of fibers, they are conveyed into the heating zone. Each support 50 is placed facing the heater 110 to allow the thermoplastic polymer fibers of the second series to melt. The diagram of FIG. 3 illustrates a support 50 covered with two sets of fibers 1 and 2, seen in cross section. The diagram of FIG. 4 makes it possible to illustrate this support 50 after melting the fibers of the second series. Only the fibers of the first series 1 can be seen on the section. In the example of the system shown in FIG. 5, the positioning device 100 comprises two tracks whose exits are in facing relation. The two series of fibers 1 and 2 are brought by the two paths on the same plane so as to come into contact and to be intercalated in a zone of vis-à-vis and form a homogeneous plane imposed by the size of the fibers. The plane formed by the two sets of fibers in contact passes for a few seconds in the heating zone provided for melting the thermoplastic polymer fibers. In this example, the calendering device 115 can additionally provide the heating function and replace the device 110. At the outlet of the calendering device, the fibrous material is obtained in the form of a strip 10 which can then be used according to needs. In this example the two sets of fibers are each driven by a treadmill type device 111 and 112. Advantageously, there can be provided rules 113 and 114 for maintaining the spacing of fibers on each of the mats. It is understood that when talking about contacting the fibers by interposing them, this is not limited to placing a fiber of a series between two fibers of the other series. Indeed, the positioning devices 100 allow

Ref: 0276B -ARK14 to place two fibers side by side of the same series between two fibers of the other series. Preferably, such an arrangement will be used to have for example a mineral fiber for two thermoplastic polymer fibers. This is not limited to placing the fibers of the two series side by side. It may also be provided, in the case where the mineral fibers are already a weave of two-way weaving type, to put the thermoplastic polymer fibers in contact with this weaving, for example by placing them on one side of the weaving, this face being then facing the heater.

Other systems, for example the mechanical systems described in US Pat. No. 6,607,626; US 6,939,424 and US 7,235,149 may also be suitable for fiber placement. A third system for implementing the method according to the invention is illustrated in the diagram of FIG. 6. Details of certain elements are illustrated in FIGS. 7 and 8. According to this preferred embodiment, the system comprises a line L. continuous formation of the material in the form of a calibrated and homogeneous band. This continuous training line comprises: the device for placing the fibers 100 equipped with: the device for unrolling the fibers, 104; this device 104 comprises fiber coils 141 for the fibers of the first series and coils 142 for the fibers of the second series. In practice, there are as many coils as fibers and a reel 143. - the preheating device 105; it has two half-ovens horizontal opening, infrared ramps. Its length is 1 m. The maximum temperature that can be reached is 600 ° C. The passage groove 13 has a section of 40x40mm approximately. the calendering device 106; it comprises two cylinders as illustrated in FIG. 8, of diameter 100 mm, width 100 mm, a polished chrome surface Ra less than 0.1 micron. The surface of the cylinders 15 and 17 has male and female elements 16 and 18 of a shape suitable for interlocking one into the other, by pressure, so as to calibrate the strip 10 in width at 6 mm, when its passage on the cylinders. This device comprises an electric heater providing a maximum temperature at about 260 ° C, a heating cartridge with rotating supply manifold and

Ref: 0276B -ARK14 regulation by a thermocouple probe on the surface, a self-aligning bearing and adjustable spacing from 0 to 2mm by screw-nut, a synchronous drive of the two cylinders by chain or toothed belt, a geared motor with brushless brushless servomotor allowing to have a maximum line speed of 30m / min and an electrical synchronization with the pulling train. The shaping device 150 equipped with: the heating device 110 identical to the preheating device 105. The temperature of this device is set to reach the melting temperature Tf of the thermoplastic polymer fibers. The half-furnace 11 comprises a passage groove 13 shown in FIG. 7; a second calendering device 115; a third calendering device 116; these calendering devices are identical to the first calendering device 106. The details of the structure of the cylinders are illustrated in the diagram of FIG. 8. The cooling device 117. It is in the form of a tray of length 1 m in stainless steel in which the band is introduced and immersed in cold water if necessary (the band is shown in dotted lines in the ferry crossing). It includes a compressed air dryer and a water cooling unit of about 3KW. - The device 118 for regulating the winding and maintaining the band preventing vibrations and operating from top to bottom on a height corresponding to the width of the winding coils 300. - The winding device 300, this device comprises several flat coils shaped slabs 301, 302 etc., about 600mm in diameter. The slabs are superimposed on a vertical axis XX as filling progresses. It is planned to store 10 to 20 pancakes with an interlayer between them. The passage of a slab 301 to the next 302 is done manually. The synchronization with pulling of the band is done by a regulating pad, the tension is regulated by the weight of the pad. - The pull train 350 which allows to drive the band continuously. It comprises elastomer rollers and allows to exert a fixed pressure by pneumatic cylinder. It is electrically synchronized with the calendering devices.

Ref: 0276B -ARK14 The continuous training line L is controlled by a control station 400, of the computer type with display screen. This station 400 is connected, for example by network, to the various electrical control devices of the line: electric motors; variable speed drives and speed controllers, temperature controllers; pulling motor to allow the different synchronizations necessary for the continuous operation of line L. This control station also allows to save all the parameters for automation and synchronization management. In the case where the mineral fibers 1 used have a coating layer (or sizing), the coating layer may be removed, if necessary, that is to say, in the event of incompatibility with thermoplastic polymer fibers to melt . The coating layer will be removed before contacting the two sets of fibers 1, 2. For this purpose, it can be expected that the fibers of the two series arrive by two separate reels so that the desizing is performed on the mineral fibers before contacting the two sets of fibers; or that the desensitization of the mineral fibers is carried out in an oven such as oven 105 before contacting the two sets of fibers in the oven 105. In addition, to obtain an improved melting and impregnation, a heating device 110 may be used. laser type instead of an infrared oven as described in the previous example. In this case, the laser device is arranged so that the laser beam arrives in the longitudinal axis of the fibers (ribbon), that is to say the axis of pulling. Thus the heating is direct and therefore concentrated on the fibers.

Preferably, the heating device 110 is of the induction heating or microwave type. Indeed, an induction heating device or microwave is particularly suitable when electrically conductive fibers are present in the assembly or when electric conductive fillers are present in the pre-impregnated material. Because, in the case of induction heating or microwave heating, the electrical conductivity of the latter is implemented and contributes to obtaining a core firing and better homogeneity of the fibrous material. The thermal conduction of the fibers of the assembly or fillers present in the preimpregnated fibrous material also contributes, with this type of heating, to core baking improving the homogeneity of the material. Ref: 0276B -ARK14 The heating by microwave or induction is particularly well adapted in the presence of charges such as carbon nanotubes NTC in the preimpregnated material because it allows to obtain a better dispersion / distribution of CNTs within of the material, leading to a better homogeneity of the physicochemical properties, and consequently better overall properties on the final product. Ref: 0276B -ARK14

Claims (21)

REVENDICATIONS1. A process for producing a fibrous material pre-impregnated with an organic polymer, comprising i) using at least two sets of different fibers, a first set of fibers comprising reinforcing fibers and a second set of fibers comprising organic polymer fibers having a melting temperature Tf, ii) arranging the two sets of fibers in contact with each other and then iii) heating all of the two series of fibers to a temperature at least equal to the melting temperature Tf organic fibers and allow to cool all to room temperature. 2. Process for manufacturing a fibrous material pre-impregnated with an organic polymer according to claim 1, characterized in that the reinforcing fibers constituting the first series are mineral fibers or organic fibers of thermoplastic or thermosetting polymer or else , mineral fibers and organic fibers of thermoplastic or thermosetting polymer. 3. Process for producing a fibrous material pre-impregnated with organic polymer according to claim 1 or 2, characterized in that the organic fibers constituting the fibers of the second series are made of thermoplastic or thermosetting polymer. 4. A method of manufacturing a preimpregnated fibrous material according to claim 2 or 3, characterized in that the polymers forming part of the thermosetting fibers are chosen from: unsaturated polyesters, epoxy resins, vinyl esters, phenolic resins, polyurethanes, cyanoacrylates and polyimides, such as bismaleimide resins, aminoplasts (resulting from the reaction of an amine such as melamine with an aldehyde such as glyoxal or formaldehyde) and mixtures thereof. Ref: 0276B -ARK14 A process for producing a preimpregnated fibrous material according to claim 4, characterized in that the unsaturated polyesters result from the condensation polymerization of dicarboxylic acids containing an unsaturated compound (such as maleic anhydride or fumaric acid) and glycols such as propylene glycol, hardened by dilution in a reactive monomer, such as styrene, and reaction of the latter with the unsaturations present on these polyesters, using peroxides or a catalyst, in the presence of salts heavy metals or an amine, or using a photoinitiator, ionizing radiation, or a combination of these different techniques. 6. Process for manufacturing a preimpregnated fibrous material according to claim 4, characterized in that the vinyl esters comprise the products of the reaction of epoxides with (meth) acrylic acid, which can be cured after dissolution in the styrene (similar to polyester resins) or organic peroxides. 7. A method of manufacturing a preimpregnated fibrous material according to claim 4, characterized in that the epoxy resins consist of materials containing one or more oxirane groups, for example from 2 to 4 oxirane functions per molecule. 8. Process for manufacturing a preimpregnated fibrous material according to claim 7, in the case where the epoxy resins are polyfunctional, these resins may consist of linear polymers bearing terminal epoxy groups, or whose backbone comprises epoxy groups. or whose backbone carries pendant epoxy groups, a hardening agent such as an acid anhydride or an amine being used. 9. A method of manufacturing a preimpregnated fibrous material according to claim 7, characterized in that the epoxy resins may result from the reaction of epichlorohydrin on a bisphenol such as bisphenol A. 10. A method of manufacturing a preimpregnated fibrous material according to claim 9, characterized in that the epoxy resins may result from a reaction with an alkyl- and / or alkenylglycidyl ethers or esters; a polyglycidyl Ref: 0276B -ARK14ethers of optionally substituted mono- and polyphenols, especially polyglycidyl ethers of bisphenol A; a polyglycidyl ether of polyols; polyglycidyl ethers of aliphatic or aromatic polycarboxylic acids; polyglycidyl esters of polycarboxylic acids; polyglycidyl ethers of novolac. 11. A method of manufacturing a preimpregnated fibrous material according to claim 9, characterized in that it is a reaction product of epichlorohydrin on aromatic amines or glycidyl derivatives of mono- or aromatic diamines . 12. A method of manufacturing a preimpregnated fibrous material according to claim 9, characterized in that cycloaliphatic epoxides and preferably diglycidyl ethers of bisphenol A (or DGEBA), F or A / F are used. 13. A method of manufacturing a preimpregnated fibrous material according to claims 2 or 3, characterized in that the thermosetting fibers are cured with a hardener or crosslinking type di-amine or tri-amine functional used at levels ranging from 1 to 5%. 14. Process for manufacturing a preimpregnated fibrous material according to claim 1, 2 or 3, according to the preceding claims, characterized in that the polymers forming part of the thermoplastic fibers consist of phenoxy polymers (or resins) which are polyhydroxyethers. terminated by alpha-glycol groups and which result from the reaction between bisphenol A and epichlorohydrin. 15. Process for manufacturing a fibrous material pre-impregnated with an organic polymer according to claim 1, characterized in that the melting temperature Tf of the fibers of the second series is always less than the melting temperature of the fibers. of the first series so that after the heating step, the fibers of the second series melt impregnate the fibers of the first series which constitutes reinforcing fibers of the fibrous material. Ref: 0276B -ARK14 16. A method of manufacturing a fibrous material pre-impregnated with organic polymer according to claim 1, 2 or 3, characterized in that the melting temperatures of the thermosetting polymer fibers are of the order of 50 ° C to 80 ° C, typically 60 ° C. Process for producing a fibrous material pre-impregnated with an organic polymer according to claim 16, characterized in that after addition of a hardener (or crosslinking agent) the melting point is between 100 ° C. and 150 ° C., typically 120 ° C. 18 Process for manufacturing a fibrous material pre-impregnated with organic polymer according to claim 1, 2 or 3, characterized in that the heating at the melting temperature Tf is associated with a shaping of all the two series of fiber and that the thermosetting polymer fibers are shaped in an apparatus normally used for a thermoplastic polymer such as a twin-screw extruder or a comangler. 19 Process for manufacturing a fibrous material pre-impregnated with an organic polymer according to claim 1, characterized in that: - the assembly of the two sets of fibers is arranged just before the heating step iii), powder-form inorganic fillers, such as metal powder, powdery carbon black, carbon fibrils, carbon nanotubes, or nanotubes of silicon carbide, boron carbonitride, boron nitride or silicon. Process for the production of a fibrous material pre-impregnated with an organic polymer according to claims 17 and 19, characterized in that the assembly of the two sets of fibers is provided with carbon nanotube powder NTC, before to introduce the hardener. 21. A method of manufacturing a fibrous material pre-impregnated with organic polymer according to claim 1, characterized in that the heating step iii) is performed by laser heating or a plasma torch, nitrogen or an oven. infrared or by induction or microwave. Ref: 0276B -ARK1422. Process for manufacturing a fibrous material pre-impregnated with an organic polymer according to Claims 19 and 21, characterized in that the heating is carried out by induction or microwaves to promote core heating. 23. A method of manufacturing a fibrous material pre-impregnated with organic polymer according to claim 21, characterized in that when the heating is carried out by induction, a conductive material is used, this material being in contact with the fiber assembly. as for example a fiber support or as conductive inorganic fillers present in the assembly itself, such as for example metal powder, powdery carbon black, carbon fibrils, carbon nanotubes, or as nanotubes of silicon carbide, boron carbonitride, boron nitride or silicon. 24. System for implementing the method according to claim 1 characterized in that it comprises a device (100) for placing the fibers so as to arrange the two series of fibers in contact with each other and a heater (110) of the two series of fibers such as laser heating or a plasma torch, nitrogen or an infrared oven or by induction or microwave. 25. System for carrying out the method according to claim 24, characterized in that the induction heating is obtained by exposing the fibers of the assembly to an alternating electromagnetic field by means of a high frequency unit of 650 KHz at 1 MHz. 26. System for implementing the method according to claim 24, characterized in that the microwave heating is obtained by exposing the fibers of the assembly to a microwave electromagnetic field by means of a microwave generator of 2 to 3 GHz. Ref: 0276B -ARK14