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    • 专利摘要:
    The invention relates to a process for preparing an electrically conductive composite film comprising at least one thermoplastic polymer resin and electrically conductive particles selected from a) graphene, carbon nanotubes, carbon nanofibers, and mixtures thereof; and b) filamentous metal nanoparticles; a method of preparing an electrically conductive laminated composite structure comprising such an electrically conductive composite film; electrically conductive composite film; said electrically conductive laminated composite structure; as well as their uses.
    公开号:FR3023746A1
    申请号:FR1457020
    申请日:2014-07-21
    公开日:2016-01-22
    发明作者:Antoine Lonjon；Eric Dantras；Colette Lacabanne
    申请人:Centre National de la Recherche Scientifique CNRS；Universite Paul Sabatier Toulouse III；
    IPC主号:
    专利说明:

    [0001] The invention relates to a method for preparing an electrically conductive composite film and an electrically conductive laminated composite structure comprising such an electrically conductive composite film, said electrically conductive composite film, said electrically conductive laminated composite structure, as well as their uses. The present invention typically, but not exclusively, applies to the automotive, railway, aeronautics, aerospace (eg electronic satellites), computer and electronics sectors, in which parts Electrically conductive composites, and in particular electrically conductive laminated composite structures, are used instead of massive metal parts. Indeed, because of their low weight, their low production cost and their adjustable mechanical properties (especially in terms of flexibility), these composite parts are increasingly used to manufacture, for example, support pieces or vehicle structures. (chassis, plates, etc ...). Added to this are other advantages over massive metal structures such as better fatigue resistance and no corrosion.
    [0002] However, these composite parts must be sufficiently conductive (e.g. conductivities greater than 0.1 S / m) to be able to replace metal parts. For example, in the field of aeronautics, they must be able to evacuate the electrical charge, and avoid the structural damage associated with lightning. Indeed, the impact of lightning on one or more composite parts of an aircraft can cause a degradation of its structure, but also its dysfunction (boosting within the electrical systems, spark and degassing at the fasteners, sparkle in the edges composite parts, critical effects in fuel zones).
    [0003] Methods of manufacturing laminated composite structures are numerous and are implemented either from dry fibers (e.g. PP000483FR fibers only) and a polymer resin in film form or in liquid form, or from prepregs. The most common methods are autoclave bag molding (ie marouflage), compression molding, resin transfer molding (also known as Resin Transfer Molding or RTM), and brewing. a resin in the form of a film or in liquid form (also well known respectively under the Anglicisms "Resin Film Infusion" or RFI, and "Liquid Resin Infusion" or LRI). Layered composite structures are most often made from thermosetting polymer resins (e.g. epoxy resins, phenolics, vinyl esters, polyesters, polyimides, etc.). Indeed, these resins are generally in solution in the form of non-crosslinked polymer suspended in a solvent. Once crosslinking is complete, these structures are solvent resistant and easy to handle. However, these laminated composite structures have the disadvantage of being poorly resistant to shocks. Moreover, once the polymerization of the thermosetting polymer resin has been carried out, the laminated composite structures are no longer transformable, which prevents their recycling and / or the repair of certain defects that would have appeared during their manufacture.
    [0004] Thus, attention has focused on the specific use of thermoplastic polymer resins [e.g. polyethersulfones (PES), polyetherimides (PEI), polyetheretherketones (PEEK), or phenylene polysulfides (PPS)) which have better impact resistance and possible post-melting shaping. For example, Grouve et al. [Plastics, Rubber and Composites, 2010, 39, 3-5, 208-215] have described the preparation of a laminated composite structure of [PPS / glass fiber] type, stacking unit stacks comprising successive layers of fibers continuous glass and PPS films, separated by tin-plated steel or aluminum plates or sheets of polytetrafluoroethylene (PTFE), by hot pressing the stack formed, then cooling. However, the resulting structure is not sufficiently conductive (e.g. conductivities less than 0.1 S / m).
    [0005] PP000483 3 Cytec Technology Corp. has developed a PEEK / carbon fiber prepreg (marketed under the reference APC-2 / AS4) in the form of a unidirectional layer (UD) containing approximately 60% carbon fiber by volume. A unidirectional web (sometimes referred to as a ribbon) consists of parallel carbon fibers oriented in one direction only. The cohesion between the carbon fibers is ensured by the PEEK. Laminated composite structures can then be obtained by stacking these UD sheets in different directions, then consolidation by the effect of temperature and sometimes pressure. In order to make the laminated composite structure sufficiently conductive, a metal grid (e.g. copper or aluminum) is incorporated in said structure. However, it is then necessary to add an insulating material such as a ply of glass fibers, in order to avoid galvanic corrosion due to the contact between the carbon fibers and the metal grid. Cytec Technology Corp. also proposes in the international application WO2013 / 032620 to prepare a laminated composite structure by stacking prepregs on which metal sheets, locks, flakes, fibers or particles of a metallic material selected from aluminum, copper, can be deposited. titanium, nickel and stainless steel to improve the electrical conductivity of the structure. However, it is not clear how these metal elements are deposited. In addition, when these metal elements do not have a form factor, they must be introduced in amounts greater than 15% by volume, inducing a degradation of the mechanical properties of the laminated composite structure. Deposition of metal particles is generally by chemical vapor deposition ("CVD"), physical vapor deposition (PVD), or aqueous chemical deposition. However, these deposition techniques require sophisticated and expensive equipment and / or the adhesion of the metal layer to the prepreg is not sufficient for the aforementioned applications. Finally, Boyer et al. [JNC reports, Poitiers 2011, "Mechanical and Electrical Behavior of a PEEK Composite / PP000483FR 4 Carbon / Carbon Nanotube"] have described a stratified composite structure comprising successive layers of PEEK / carbon fiber prepregs and composite films PEEK / carbon nanotubes (NTC). The presence of PEEK / NTC composite film layers makes it possible to improve the transverse electrical conductivity of the structure (i.e. in the direction of its thickness or in the direction perpendicular to the carbon fibers). The composite film is prepared by hot extruding a mixture of PEEK and NTC using a bis-screw extruder to form granules, and shaping the granules under heat press. Indeed, the methods for mixing and / or forming a mixture of a thermoplastic polymer resin with conductive particles generally used to manufacture a composite in the form of a film or pellet use the thermoplastic polymer resin in the state melted and therefore require the use of very high temperatures (300 to 400 ° C). However, these methods such as extrusion, injection molding, molding or hot pressing induce high production costs, and they are unsuitable, especially when the conductive particles have a high form factor ( eg carbon nanotubes, carbon fibers). Indeed, the extrusion mixture causes shear forces that break said particles, reduce their form factor, and the final conductivity of the composite; and forming in press, injection molding or extrusion directs the high form factor conductive particles in the material direction, thereby decreasing the homogeneous dispersion of said particles in the composite, and thus its final conductivity. In addition, increasing the volume ratio of conductive particles to improve the conductivity degrades the mechanical properties of the structure. Thus, all of the existing techniques provide laminated composite structures which do not have the mechanical and / or electrical properties sufficient to be used in the aforementioned fields of application. Thus, the object of the present invention is to overcome the drawbacks of the aforementioned prior art and to provide a method for preparing an electrically conductive composite PP000483FR film based on thermoplastic polymer resin and electrically conductive particles, said process being economical , easy to implement, can be used with any type of thermoplastic polymer resin and to maintain good mechanical properties. In addition, another object of the present invention is to develop a method for preparing an electrically conductive laminated composite structure based on thermoplastic polymer resin, electrically conductive particles, and long or continuous fibers, said process being economical , easy to implement, and can be used with any type of thermoplastic polymer resin and to maintain good mechanical properties. Finally, the other objects of the invention are to provide an electrically conductive composite film based on thermoplastic polymer resin and high-form factor electrically conductive particles, as well as an electrically conductive laminated composite structure based on thermoplastic polymer resin, high form factor electrically conductive particles, and long or continuous fibers, having sufficient electrical conductivity for them to be used in the aforementioned advanced applications. These objects are achieved by the invention which will be described below. The invention therefore firstly relates to a process for preparing an electrically conductive composite film comprising at least one thermoplastic polymer resin and electrically conductive particles chosen from: a) graphene, carbon nanotubes, carbon nanofibers, and their mixtures; and b) filamentary metal nanoparticles, said electrically conductive composite film optionally impregnating fibers, said process being characterized in that it comprises at least the following steps: 1) a step of preparing a suspension comprising a solvent and electrically conductive particles selected from: a) graphene, carbon nanotubes, carbon nanofibers, and mixtures thereof; and b) filamentary metal nanoparticles, said suspension comprising from about 0.06% to about 0.5% by volume of said electrically conductive particles to the total volume of the suspension, 2) a step of mixing a resin powder thermoplastic polymer of particle size less than or equal to about 50 am with the suspension prepared in the preceding step to obtain a homogeneous suspension, said homogeneous suspension comprising from 7% to about 20% by volume of said thermoplastic polymer resin relative to the total volume of the suspension, 3) a step of depositing the homogeneous suspension of the preceding step on a non-stick or fibrous support, 4) a drying step, 5) a heat treatment step at a temperature greater than or equal to the temperature melting the thermoplastic polymer resin when it is in semi-crystalline form or greater than or equal to its trans temperature vitreous ion when it is in amorphous form, in order to obtain an electrically conductive composite film deposited on said non-stick support or impregnating said fibrous support, and 6) a step of removal of the electrically conductive composite film from the support when the support is a nonstick medium. When the support is a release-resistant support, step 6) makes it possible to lead to a self-supporting electrically conductive composite film comprising at least one thermoplastic polymer resin and from about 1% to about 10% by volume of electrically conductive particles with respect to total volume of the electrically conductive composite film. In a particular embodiment, the self-supporting electrically conductive composite film comprises from about 1 to about 5% by volume of electrically conductive particles, and preferably from about 2 to about 4% by volume of electrically conductive particles relative to the total volume of said film. self-supporting electrically conductive composite. The use of these small amounts of electrically conductive particles makes it possible to lead to a self-supporting electrically conductive weakly charged composite film, while retaining its mechanical properties. It should be noted that the use of an amount of electrically conductive particles greater than 10% by volume in the self-supporting electrically conductive composite film can lead to degradation of its mechanical properties. When the support is a fibrous support, step 5) leads to an electrically conductive composite film impregnating said fibrous support (i.e. the fibers of said fibrous support). Thus, an electrically conductive composite prepreg comprising at least one thermoplastic polymer resin, having from 1 to 10% by volume of electrically conductive particles, and from 10 to 70% by volume of fibers, based on the total volume of the composite prepreg, is obtained. electrically conductive. In a particular embodiment, the electrically conductive composite prepreg comprises from about 1 to about 5% by volume of electrically conductive particles and from about 10 to about 70% by volume of fibers, based on the total volume of the electrically conductive composite prepreg, and preferably about 2 to 4% by volume of electrically conductive particles and about 10 to 70% by volume of fibers, based on the total volume of said electrically conductive composite prepreg. The use of these small amounts of electrically conductive particles leads to a weakly charged electrically conductive composite prepreg while retaining its mechanical properties.
    [0006] PP000483 8 It should be noted that the use of a quantity of electrically conductive particles greater than 10% by volume in the electrically conductive composite prepreg can lead to a degradation of its mechanical properties.
    [0007] Thus, the process of the invention makes it possible to obtain, in a few steps, an electrically conductive composite film based on thermoplastic polymer resin and electrically conductive particles, while avoiding processes such as those described in the prior art which at least one step of mixing a thermoplastic polymer resin in the molten state with electrically conductive particles. Furthermore, the method of the invention avoids any shaping step which would have the effect of degrading its volume or transverse conduction properties such as extrusion, hot pressing or injection molding. In the present invention, the term "suspension" means a dispersion of an insoluble (or practically insoluble) solid (powder) and finely divided in a liquid medium. It is therefore a heterogeneous system consisting of a continuous liquid external phase (solvent) and a solid internal phase. The solvent of step 1) can be chosen from hydrocarbon solvents such as alkanes, alkenes, toluene or xylene, oxygenated solvents such as alcohols, ketones, acids, esters, dimethylformamide (DMF). ) or dimethylsulfoxide (DMSO), chlorinated solvents, water, and mixtures thereof. The solvent of step 1) is preferably a solvent which can be readily evaporated to facilitate drying of step 4). The most preferred solvent of step 1) is an alcohol such as ethanol. The solvent of step 1) must be inert with respect to the electrically conductive particles and the thermoplastic polymer resin. In a particular embodiment, graphene is in the form of particles whose average size varies from about 2 to about 100 nm.
    [0008] PP000483 9 Carbon nanotubes are in particular an allotropic form of carbon belonging to the family of fullerenes. More particularly, the carbon nanotubes are layers of graphene wound on themselves and closed at their ends by half-spheres similar to fullerenes. In the present invention, the carbon nanotubes comprise both single-walled nanotubes (single wall carbon nanotubes, SWNTs) comprising a single sheet of graphene and multiwall or multiwall nanotubes (in English: Multi Wall Carbon Nanotubes, MWNT ) comprising several sheets of graphene nested inside each other in the manner of Russian dolls, or a single sheet of graphene rolled up several times on itself. In a particular embodiment, the carbon nanotubes have a mean diameter ranging from 1 to about 50 nm.
    [0009] The carbon nanotubes may have a length ranging from 1 to 10 pm approximately. Carbon nanofibers (or carbon fibrils) consist of more or less organized graphitic zones (or turbostratic stacks) whose planes are inclined at variable angles with respect to the axis of the fiber. These stacks may take the form of platelets, fish bones or stacked cups to form structures having an average diameter generally from about 100 nm to about 500 nm or more. The carbon nanofibers may have a length ranging from about 1 to 10 μm.
    [0010] The metal of said filiform metal nanoparticles may be a stainless metal, that is to say that does not react with the oxygen of the air to form a so-called "passivation" layer. According to a preferred embodiment of the invention, the metal is selected from silver, gold, platinum and a mixture of two or three of said metals.
    [0011] PP000483EN The particularly advantageous metal is silver. In the present invention, the expression "filiform nanoparticles" means particles having: - a length (L1), extending in a main direction 5 of elongation, - two dimensions (D1) and (MI said orthogonal dimensions, s extending in two transverse directions orthogonal to each other and orthogonal to said main direction of elongation, said orthogonal dimensions (D1, D2) being smaller than said length (L1) and less than 10 500 nm, and, - two ratios (F1) and (F2), said form factors, between said length (L1) and each of the two orthogonal dimensions (D1) and (MI said shape factors (F1, F2) being greater than 50. The expression "form factor" signifies the ratio between the length (L1) of a filamentary nanoparticle, and one of the two orthogonal dimensions (D1, D2) of said filiform nanoparticle.according to a preferred embodiment, the two orthogonal dimensions (D1, D2) of a n Filiform anoparticle are the diameter (D) of its cross section. This is called a "nano-stick" or "nano-wire". A filamentary nanoparticle may also be a "ribbon" in which the two orthogonal dimensions of the filiform nanoparticle according to the invention are its width (L2) (first orthogonal dimension) and its thickness (E) (second orthogonal dimension). More particularly, filiform metal nanoparticles according to the invention are advantageously characterized by at least one of the following characteristics: the two orthogonal dimensions (D1, D2) of the filiform nanoparticles are between approximately 50 nm and 250 nm, and preferably between 100 nm and 200 nm; The length (L1) is from about 1 pm to about 150 pm, and preferably from about 25 pm to about 70 pm; the form factors (F1, F2) are between 100 and approximately 200, and preferably of the order of 150 approximately.
    [0012] According to a particular embodiment of the invention, the electrically conductive particles have a form factor greater than or equal to 50, and preferably greater than or equal to 100. Such electrically conductive particles are chosen from: a ') the nanotubes of carbon, carbon nanofibers, and their mixture; and b ') filamentary metal nanoparticles. The filiform metallic nanoparticles are very particularly preferred. Indeed, the inventors of the present application have discovered that the use of volume amounts ranging from 1 to about 10% of filiform metallic nanoparticles makes it possible to obtain a sufficiently conductive composite film, whereas it takes at least 15 to 20 % by volume of metal particles in the form of spherical particles, flakes, or powder, in order to obtain an equivalent conductivity. However, with such volume proportions, degradation of the mechanical properties is observed. The filiform metal nanoparticles of the invention possess two essential characteristics for the preparation of electrically conductive composite films with low charge. Their form factor is high (between 50-200), which makes it possible to reach percolation thresholds for small amounts of conductive filler. In addition, these filiform nanoparticles being metallic, they have the intrinsic conductivity of the metal that constitutes them. The suspension of step 1) may further comprise metal particles other than filiform metal nanoparticles.
    [0013] The metal of these metal particles has the same definition as the metal of filiform metallic nanoparticles. The metal of these metal particles is preferably identical to the metal of the filiform metallic nanoparticles.
    [0014] The metal particles may be in the form of nanometric and / or micrometric spherical metal particles, powder or flakes. According to a preferred embodiment, the suspension of step 1) does not comprise pigment and / or dye. Indeed, the pigments 10 (e.g. inorganic fillers) and / or dyes generally used can alter the mechanical properties of the conductive film. Step 1) may be carried out using mechanical agitation and / or ultrasound, in particular at a frequency ranging from about 20 kHz to about 170 kHz, and at a power ranging from about 5 W to about 500 W. by pulse of 15 seconds. The thermoplastic resin of step 2) may be chosen from polyaryletherketones (PAEK) such as polyetheretherketones (PEEK), polyetherketoneketones (PEKK), polyetheretherketoneketones (PEEKK), polyetherketones (PEK), or polyetherketoneetherketoneketones (PEKEKK) ; Phenylene polysulfides (PPS); polyetherimides (PEI); polyethersulfones (PES); polysulfones (PS); polyamides (PA) such as nylon; polyimides (PI); polyamideimides (PAI); polycarbonates (PC); polyvinylidene fluorides (PVdF); copolymers of polyvinylidene fluoride and trifluoroethylene [P (VdF-TrFE)] or hexafluoropropene [P (VdF-HFP)]; and their mixtures. The thermoplastic resin of step 2) is preferably chosen from polyetheretherketones (PEEK), polyetherketoneketones (PEKK), phenylene polysulfides (PPS) and polyamides (PA). The suspension prepared in step 2) may have a viscosity ranging from about 1 Pa.s to about 33 Pa, and preferably from about 1 Pa.s to about 10 Pa.s at 25 ° C. Unless otherwise indicated, the viscosity values given in the present application, and in particular the viscosity value of the suspension, were determined at 25 ° C, at a shear rate of 0.5 rad.s-1 and measured using a rotary rheometer sold under the trade name ARES by Rheometric Scientific equipped with a Couette cell. The rheological measurement time corresponding to a deformation ranging from 0 to 30% is about 300 seconds. The viscosity of the suspension of step 2) must be sufficient to form a conductive film with a uniform thickness, and it must not be too large to lead to a conductive film.
    [0015] In step 2), the viscosity of the slurry can be adjusted by adding an appropriate amount of a solvent identical to that used in step 1). The suspension of step 2) preferably comprises from about 7% to about 12% by volume of thermoplastic polymer resin based on the total volume of the suspension. In the suspension of step 2), the ratio of the mass of solvent to the mass of total solids (i.e. mass of thermoplastic polymer resin + mass of electrically conductive particles) can range from about 0.5 to about 4. The thermoplastic resin used in step 2) is not soluble in the solvent of step 1). It preferably has a particle size less than or equal to approximately 30 μm, and more preferably less than or equal to approximately 20 μm. Step 2) can be carried out by means of mechanical agitation and / or ultrasound, in particular at a frequency ranging from about 20 kHz to about 170 kHz, and at a power ranging from 5 W to 500 W about 5 seconds pulse. This step 2) avoids the use of melt blending methods of the thermoplastic polymer resin with the electrically conductive particles such as those described in the prior art. In fact, as explained above, these methods (eg extrusion, injection molding, hot molding, hot pressing, etc ...) implement the thermoplastic polymer resin in the molten state and induce costs. of high production, as well as a degradation of the electrical properties of the electrically conductive particles. According to a preferred embodiment of the invention, the suspension of step 2) consists only of the thermoplastic polymer resin, the solvent and the electrically conductive particles. According to a first variant of the invention, the deposition of step 3) can be carried out according to the following substeps: 3a) a step of introducing the homogeneous suspension of step 2) into a reservoir comprising a injection nozzle in its lower part, and the maintenance of the suspension with mechanical stirring, 3b) a step of applying the suspension on a non-stick or fibrous support, with the aid of said injection nozzle and a squeegee (eg flexible steel blade) located at the outlet of the nozzle. According to this first variant, step 3b) makes it possible to form a suspension layer deposited on the non-stick or fibrous support. The squeegee may be adjusted in height relative to the support to form a more or less thick suspension layer deposited on said support. The suspension layer may be in the form of a finite-dimensional layer or a continuous layer. To form a continuous suspension layer, steps 3a) and 3b) can be performed simultaneously. In addition, step 3b) can be implemented using a roller for continuously scrolling the support at the injection nozzle and under the doctor blade, at a given speed. When the support is a fibrous support, the suspension layer 30 progressively impregnates said fibrous support.
    [0016] In this first variant of the invention, the suspension of step 3a) has a viscosity preferably ranging from about 1 Pa.s to about 10 Pa.s. The release medium may be a polyimide sheet such as, for example, that marketed under the reference Upilex®, or a metal sheet which has been rendered non-stick by suitable treatment, in particular by means of a release agent such as by example that marketed under the reference Cirex Si041WB® by Sicomin. The fibrous support is a carrier comprising long or continuous fibers. In the invention, the term "long fibers" means fibers of at least about 1 mm in length. The fibers of the fibrous support are preferably continuous. The fibers may be selected from carbon fibers, glass fibers and aramid fibers. Carbon fibers are preferred. The fibers can be in the following forms: linear (threads, locks) or surface fabrics (fabrics, mats). A fabric is constituted by the intertwining of warp threads and weft threads. A fabric is balanced if the warp weight is equal to the weft weight. It is called unidirectional (i.e. UD) if the chain weight represents more than 70% of the total weight. For example, the webs (called ribbons in some cases) consist of parallel fibers oriented in one direction only. The transverse cohesion is ensured either by an adhesive tape arranged according to a determined pitch; either by a light weave, we obtain a unidirectional fabric in which the mass of fibers in the warp direction represents 98% of the total mass and the remaining 2% provide transverse cohesion.
    [0017] The most common fabrics are: - the taffeta (or canvas) in which the warp and weft threads intersect alternatively; the satin: the warp yarn floats above several weft yarns, for example, in a satin of 5, the warp yarn floats above 4 weft yarns; the twill in which the warp yarn floats above one or more weft yarns and then passes below one or more weft yarns, the difference with the satin is the offset of the weaving points between two consecutive strands which never touch each other for satin. Fabrics are easier to handle than tablecloths and offer interesting properties in two directions. The fiber mats are made by sets of son whose lengths are generally of the order of 50 mm. According to this first variant, the fibrous support is preferably a fiber fabric, a unidirectional fiber alignment or a fiber mat. According to a second variant of the invention, the deposition may be carried out according to the following substeps: 3a ') a step of introducing the homogeneous suspension of step 2) into a reservoir and its maintenance with mechanical stirring, 3b ') a step of immersing a fibrous support in the suspension. This second variant makes it possible to form a fibrous support impregnated with said suspension. According to this second variant of the invention, the suspension of step 3a ') has a viscosity ranging preferably from 5 Pa.s to approximately 10 Pa.s. The fibrous support is as defined previously. According to this second variant, the fibrous support is preferably unidirectional.
    [0018] The duration and the drying temperature used in step 4) are adapted to the nature of the suspension of step 2) (i.e. type of thermoplastic polymer resin, solvent, etc ...). The drying makes it possible to evaporate the solvent of stage 1).
    [0019] It may be carried out in an oven, in particular at a temperature ranging from about 25 ° C. to 180 ° C. Step 4) can last from about 15 minutes to 15 hours, and preferably from 15 minutes to about 1 hour. Step 4) in particular leads to a thin film of agglomerated powder in which the electrically conductive particles are entangled in the thermoplastic polymer resin powder. This agglomerated powder comprises a homogeneous mixture of powders of electrically conductive particles and thermoplastic polymer resin. It then does not include any solvent. This powder can impregnate the support when it is fibrous. Step 5) can be carried out at a temperature ranging from about 200 ° C to about 400 ° C. This step 5) can be carried out in a conventional oven or an infrared oven.
    [0020] Step 5) can last from about 5 minutes to 1 hour, and preferably from about 5 to 15 minutes. Step 6) can be performed using a recovery roller. The self-supporting electrically conductive composite film obtained in step 6) or the electrically conductive composite prepreg obtained in step 5) can be used directly for the preparation of a laminated composite structure. The electrically conductive composite film may be in the form of a film, a ribbon, or a sheet, continuous or of finite dimensions.
    [0021] The electrically conductive composite prepreg may be in the form of a prepreg, a ribbon, or a sheet, continuous or of finite dimensions. The thickness of the self-supporting electrically conductive composite film 5 may range from about 10 μm to 150 μm, and preferably from 50 μm to about 100 μm. Below 10 μm, homogeneous conductivity of the self-supporting electrically conductive composite film is not guaranteed, and above 150 μm the production cost of the self-supporting electrically conductive composite film becomes high. The thickness of the electrically conductive composite prepreg may range from about 100 μm to about 400 μm, and preferably from about 150 μm to about 200 μm. When the slurry of step 1) further comprises metallic particles other than filiform metal nanoparticles, the self-supporting film obtained in step 6) or the electrically conductive composite prepreg obtained in step 5) may comprise 0, 5% to 10%, and preferably from 0.2% to 4% by volume of said metal particles relative to the total volume of self-supporting film or electrically conductive composite prepreg. In the invention, the expression "autosupported film or electrically conductive composite prepreg" means a self-supporting film or a composite prepreg having a surface resistivity strictly less than 10,000 ohms / square, especially when the electrically conductive particles are carbon nanotubes. , graphene, carbon nanofibers, or mixtures thereof, preferably strictly less than 100 ohms / square, especially when the electrically conductive particles are filamentary metal nanoparticles, and more preferably strictly less than 10 ohms / square. According to a particularly preferred embodiment of the invention, the support used is a non-stick support and the electrically conductive particles are filiform metallic nanoparticles such as silver nanowires, so as to obtain a film self-supporting electrically conductive composite comprising at least one thermoplastic polymer resin and filiform metal nanoparticles such as silver nanowires. The autosupported film and the electrically conductive composite prepreg do not preferably comprise pigment and / or dye. Indeed, the pigments and / or dyes generally used can alter their mechanical properties.
    [0022] The subject of the invention is a method for manufacturing an electrically conductive laminated composite structure comprising at least one thermoplastic polymer resin, fibers, and electrically conductive particles chosen from: a) graphene, carbon nanotubes, nanofibers carbon, and mixtures thereof; and b) filamentary metal nanoparticles, said method being characterized in that it comprises one of the following two steps: i-1) a step of preparing a successive stack of at least one self-supporting electrically conductive composite film as obtained in the process according to the first subject of the invention and at least one layer of fibers, or i-2) a step of preparing a stack of at least two electrically conductive composite prepregs, which are identical or 25, as obtained in the process according to the first subject of the invention, and a thermoforming step ii). The thermoplastic polymer resin and the electrically conductive particles are as defined in the first subject of the invention. The at least two conductive electrically conductive prepregs are preferably identical. The thermoforming step ii) is conventionally carried out at a temperature greater than or equal to the melting temperature of the thermoplastic polymer resin when it is in semicrystalline form or greater than or equal to its glass transition temperature when the latter is is in amorphous form. Indeed, when the thermoplastic polymer resin is in amorphous form (eg PEI, PI) and is heated to a temperature greater than or equal to its glass transition temperature, it is found in a rubbery state, so it becomes easy to give it a new form. On the other hand, in the case of using a thermoplastic polymer resin in semi-crystalline form (e.g. PPS, PAEK, PA), a temperature greater than or equal to its melting temperature is required to perform step ii). When the two electrically conductive composite prepregs differ in the type of thermoplastic polymer resin used, step ii) is carried out at a temperature greater than or equal to the highest temperature of the melting and / or glass transition temperatures of the different resins. thermoplastic polymers used. The thermoplastic polymer resin provides cohesion between the fibers so as to distribute the mechanical stresses. The fibers provide the function of mechanical resistance to forces. The arrangement of the fibers, their orientation, make it possible to reinforce the mechanical properties of the structure. To obtain good elastic mechanical properties, there must be no slippage or separation between the different phases of the structure. The fibers are as defined in the first subject of the present invention. In a preferred embodiment, the fibers of step i-1) are in the form of a fiber fabric, a unidirectional fiber alignment or a fiber mat.
    [0023] When stacking step i-1), the fiber layers are preferably oriented in different directions, for example in the following successive orientations: 0 °, 45 °, 90 °, -45 °, 0 °, 45 °, 90 °, -45 °, etc ....
    [0024] During the stacking of step i-2), the electrically conductive composite prepregs are preferably oriented in different directions, for example in the following successive orientations: 0 °, 45 °, 90 °, -45 °, 0 ° °, 45 °, 90 °, -45 °, etc .... Step ii) can be performed at a temperature ranging from about 200 ° C to about 400 ° C. This step ii) can be carried out by heating the pressure stack in a preform to give the final shape of the laminated composite structure or using a conventional hot plate press. Step ii) can last from about 10 minutes to 1 hour, and preferably from about 15 minutes to about 30 minutes. Step ii) can be carried out at a pressure of from about 0.1 MPa to about 2 MPa, and preferably from about 0.3 MPa to about 1.8 MPa. The process according to the present invention and in particular the thermoforming step ii) does not degrade the electrical properties of the electrically conductive composite film or prepreg used in step i-1) or i-2). The pressure exerted during step ii) makes it possible to incorporate the electrically conductive particles into the fibers in a homogeneous manner. The laminated composite structure may comprise from 2 to 128 plies, and preferably from 4 to 64 plies. The laminated composite structure may have a density of from about 1.58 to about 2, and preferably from about 1.65 to 1.75. In the invention, the term "electrically conductive laminated composite structure" means a structure having a transverse or volume conductivity greater than or equal to 0.1 S / m, preferably greater than or equal to 10 S / m, and more preferably greater than or equal to 100 S / m. The third subject of the invention is a method for manufacturing an electrically conductive laminated composite structure comprising at least one thermoplastic polymer resin, fibers and electrically conductive particles chosen from: a) graphene, carbon nanotubes, nanofibers carbon, and mixtures thereof; and b) filamentary metal nanoparticles, said method being characterized in that it comprises at least the following steps: A) a step of preparing at least one unitary stack, comprising a first self-supporting electrically conductive composite film such as obtained in the process according to the first subject of the invention, a layer of fibers, and optionally a second self-supporting electrically conductive composite film as obtained in the process according to the first subject of the invention, B) a thermoforming step to form a first electrically conductive composite prepreg film, C) repeating steps A) and B) so as to form at least a second electrically conductive composite prepreg film; D) a stack preparation step; of several identical or different electrically conductive composite prepreg films, as obtained in steps B) and C), and E) a thermoforming step. The thermoplastic polymer resin and the electrically conductive particles are as defined in the first subject of the invention. The thermoplastic polymer resin provides cohesion between the fibers so as to distribute the mechanical stresses. Fibers provide the function of mechanical stress resistance. The arrangement of the fibers, their orientation, make it possible to reinforce the mechanical properties of the structure. To obtain good elastic mechanical properties, there must be no sliding or separation between the different phases of the structure.
    [0025] The fibers are as defined in the first subject of the present invention. In a preferred embodiment, the fibers of step A) and / or C) are in the form of a fiber fabric, a unidirectional fiber alignment or a fiber mat.
    [0026] Said first and second self-supporting electrically conductive composite films used in step A) may be identical or different. They are preferably identical. When said first and second self-supporting electrically conductive composite films differ in the type of thermoplastic polymer resin used, step B) is carried out at a temperature greater than or equal to the highest temperature of the melting and / or glass transition temperatures of the different thermoplastic polymer resins used. The thermoforming step B) can be carried out at a temperature of from about 200 ° C to about 400 ° C. This step B) can be performed using a roller or a press with heated bands. Step B) can be carried out at a pressure ranging from about 0.1 MPa to about 2 MPa, and preferably from about 0.3 MPa to about 1.8 MPa. The thermoforming step B) does not degrade the electrical properties of the self-supporting electrically conductive composite film used in step A). Step B) can last from about 10 minutes to 1 hour, and preferably from about 15 minutes to about 30 minutes.
    [0027] The electrically conductive composite preimpregnated film obtained in step B) or C) may be in the form of a film, a ribbon, or a sheet, continuous or of finite dimensions. During the stacking of step D), the electrically conductive composite prepreg films can be oriented in different directions, for example in the following successive orientations: 0 °, 45 °, 90 °, -45 °, 0 ° , 45 °, 90 °, -45 °, etc. The electrically conductive composite prepreg films are preferably identical. When the electrically conductive composite prepreg films differ in the type of thermoplastic polymer resin used, step E) is carried out at a temperature greater than or equal to the highest temperature of the melting and / or glass transition temperatures of the different resins. thermoplastic polymers used. The thermoforming step E) can be carried out at a temperature of from about 200 ° C to about 400 ° C. Step E) can be carried out at a pressure ranging from about 0.1 MPa to about 2 MPa, and preferably from about 0.3 MPa to about 1.8 MPa. The thermoforming step E) does not degrade the electrical properties of the electrically conductive composite prepreg films prepared in steps B) and C). Step E) can last from about 10 minutes to 1 hour, and preferably from about 15 to 30 minutes. This step E) can be carried out by heating the pressure stack in a preform to give the final shape of the laminated composite structure or using a conventional hot plate press. In a particular embodiment, the electrically conductive composite prepreg films are continuous ribbons which are heated and pressed simultaneously by sequentially winding these ribbons around a preform. The method of the invention may further comprise after step E), a step F) of consolidating the laminated composite structure in an autoclave (i.e. pressurized oven). This consolidation step F) corresponds to a heating of the laminated composite structure to a temperature greater than the melting or glass transition temperature of the polymer thermoplastic resin and a given pressure. This step makes it possible to reduce the porosity rate contained in the composite structure. The laminated composite structure may comprise from 2 to 128 plies, and preferably from 4 to 64 plies. The laminated composite structure may have a density of from about 1.58 to about 2, and preferably from about 1.65 to 1.75. The fourth object of the invention is a self-supporting electrically conductive composite film comprising at least one thermoplastic polymer resin and from about 1% to about 10% by volume, based on the total volume of the self-supporting electrically conductive composite film, of electrically conductive particles selected from A) graphene, carbon nanotubes, carbon nanofibers, and mixtures thereof; and b) threadlike metal nanoparticles. The thermoplastic polymer resin and the electrically conductive particles are as defined in the first subject of the invention. The fifth subject of the invention is an electrically conductive composite prepreg comprising at least one thermoplastic polymer resin, from about 10% to about 70% by volume of fibers, and from about 1% to about 10% by volume, based on the total volume of the polymer. electrically conductive composite prepreg, of electrically conductive particles selected from: a) graphene, carbon nanotubes, carbon nanofibers, and mixtures thereof; and b) threadlike metal nanoparticles. The thermoplastic polymer resin, the electrically conductive particles and the fibers are as defined in the first subject of the invention. The sixth object of the invention is an electrically conductive laminated composite structure comprising any one of the following stacks: a successive stack of at least one self-supporting electrically conductive composite film as obtained in the process according to the first object of the invention; invention or according to the fourth subject of the invention, and at least one layer of fibers, or - a stack of at least two electrically conductive composite prepregs, identical or different, as obtained in the process according to first object of the invention, or according to the fifth object of the invention, or - a stack of at least two identical or different unitary stacks, comprising a first self-supporting electrically conductive composite film 20 as obtained in the method according to to the first subject of the invention or according to the fourth subject of the invention, a layer of fibers, and possibly a second film comprising self-supporting electrically conductive osite as obtained in the process according to the first subject of the invention or according to the fourth subject of the invention. The seventh object of the invention is the use of an electrically conductive composite film as obtained in the process according to the first subject of the invention or according to the fourth subject of the invention for imparting electrical conductivity to a composite or composite prepreg, or improve their electrical conductivity.
    [0028] The eighth object of the invention is the use of an electrically conductive laminated composite structure as obtained in the method according to the second or third subject of the invention, or according to the sixth object of the invention to replace massive metal structures, especially in the field of aeronautics, or to manufacture support parts or vehicle structures (chassis, plates, etc ...). The present invention is illustrated by the following examples, to which it is however not limited. EXAMPLES The raw materials used in the examples are listed below: polyetherketoneketone resin (PEKK), Kepstan 6003, Arkema, particle size powder of approximately 20 μm, Arkema, phenylene polysulfide resin (PPS): Fortron 0205B4, powder particle size of about 20 μm, Celanese, ethanol, 99.8% purity, Sigma Aldrich, multiwall carbon nanotubes, Graphistrength C100, Arkema, carbon black , Sigma Aldrich, <500 nm, 20 - carbon fiber fabrics, Hexforce G0904 D1070 TCT, 193 g / m2, Hexcel Taffeta, - non-stick support: Upilex polyimide sheet, or non-stick metal sheet made using Siomin® Cirex Si041WB® Release Agent, Unless otherwise indicated, all of these raw materials were used as received from manufacturers. The ultrasonic apparatus used in the examples below is sold under the trade name Vibracell 65115 by Fisherbioblock.
    [0029] EXAMPLE 1 Preparation of an electrically conductive composite film according to the invention and prepared according to the process according to the invention A suspension of 2861 ml comprising 207.1 g of silver nanowires and ethanol was prepared. The silver nanowires were previously prepared according to a solution growth method from silver nitrate (AgNO3) and polyvinylpyrrolidone (PVP) as described by Sun Y.G. et al., "Crystalline silver nanowires by soft solution processing". Nano Letters, 2002. 2 (2): p. 165-168, with a PVP / AgNO3 ratio of 1.53. The 10 silver nanowires obtained have a length ranging from about 10 to 100 amps, and a width ranging from about 120 to 400 nm. The silver nanowire suspension was mixed with 1000 g of Kepstan® 6003 thermoplastic polymer resin using mechanical stirring (100 rpm propeller) and ultrasound at 50 kHz frequency and power of 25 W per pulse of 5 seconds. A homogeneous suspension comprising ethanol, PEKK resin, and silver nanowires was thus obtained. The suspension had a viscosity of about 3 Pa.s. The suspension was introduced into a reservoir comprising an injection nozzle in its lower part, and was applied to the Upilex® or Cirex Si041WB® non-stick support using said injection nozzle, and a doctor blade. located at the outlet of said nozzle. To form a continuous suspension layer, a roller for continuously scrolling the release media at the injection nozzle and under the doctor blade was used. The roller speed was about 2 cm / second. The slurry layer was then dried at a temperature of about 150 ° C and heat treated in a conventional oven at a temperature of about 350 ° C for about 5 minutes to form an electrically conductive composite film deposited on said release media. Said electrically conductive composite film was then peeled off the release liner to form a self-supporting electrically conductive composite film comprising PEKK and 2.5% by volume silver nanowires. It had a resistivity of 0.6 ohm / square. Figure 1 is a schematic representation of the device used to perform the method according to the first object of the invention.
    [0030] Said device comprises a roll 1 which makes it possible to continuously scroll a non-stick or fibrous support 2. A homogeneous suspension comprising at least one thermoplastic polymer resin and electrically conductive particles is introduced into a reservoir 3 comprising an injection nozzle 4 in its lower part, and is kept under mechanical stirring. This suspension is applied to the release medium 2 by means of said nozzle 4, and a doctor blade 5 located at the outlet of the nozzle 4 to form a suspension layer 6 deposited on the non-stick support or impregnating the fibrous support. This layer is dried in a dryer 7. The vapor recovery can be carried out using a ventilation and condensation system 8 for the recovery of the solvent. Then the dried suspension layer is heat-treated in a furnace 9 at a temperature greater than or equal to the melting temperature of the thermoplastic polymer resin to form an electrically conductive composite film or prepreg 10. The device may also comprise a recovery roller 11 FIG. 2 shows the electrically conductive composite film according to the invention and as obtained in this example, by scanning electron microscopy (SEM-FEG) carried out with a microscope equipped with a field emission gun sold under the trade name JEOL JSM 6700F by the company JEOL. EXAMPLE 2 Preparation of an electrically conductive laminated composite structure according to the invention and prepared according to the process according to the invention A laminated composite structure was manufactured by manual preparation of a successive stack of an electrically conductive composite film. as obtained in Example 1, a layer of a fiber fabric, an electrically conductive composite film as obtained in Example 1, and a fiber layer (ie 2-ply stack). [PEKK film-silver nanowires / fiber fabric layer] z), and by thermoforming the stack at a temperature of 350 ° C and a pressure of 0.5 MPa for 15 min, using a press sold under the trade name CARVER 4128CE by the company CARVER. When stacking 2 folds, the fiber layers are oriented in the 0 ° and 45 ° successive orientations.
    [0031] The laminated composite structure obtained had a density of 1.65 and a conductivity of 200 S / m. A laminated composite structure was manufactured by manual preparation of a 4-ply stack: [PEKK film-silver nanowires / fiber fabric layer] 4, and by thermoforming the stack at a temperature of 350 ° C and a pressure 0.5 MPa for 15 min using the same press as described above. When stacking 4 folds, the fiber layers are oriented in successive orientations 0 °, 45 °, 0 ° and 45 °. The laminated composite structure obtained had a density of 1.805 and a conductivity of 350 S / m. FIG. 3 shows the laminated composite structure (4-ply stack) according to the invention and as obtained in this example, by scanning electron microscopy (SEM-FEG) carried out with a microscope equipped with a field emission gun sold under the trade name JEOL 25 JSM 6700F by JEOL.
    [0032] EXAMPLE 3 Preparation of an electrically conductive composite film according to the invention and prepared according to the process according to the invention A 5800 ml suspension comprising 28.35 g of carbon nanotubes and ethanol was prepared using ultrasound at a frequency of 20 kHz and a power of 500 W per pulse of 5 seconds for 2 min. The suspension of carbon nanotubes was mixed with 826 g of Kepstan® 6003 thermoplastic polymer resin using mechanical stirring (100 rpm propeller) and ultrasound at a frequency of 20 kHz and power. 500 W per pulse of 5 seconds. A homogeneous suspension comprising ethanol, PEKK resin, and carbon nanotubes was thus obtained. The suspension had a viscosity of about 5 Pa.s. The suspension was introduced into a reservoir comprising an injection nozzle in its lower part, and was applied on the non-stick support with the aid of said injection nozzle, and a doctor blade located at the outlet of said nozzle. nozzle. To form a continuous suspension layer, a roller for continuously scrolling the release media at the injection nozzle and under the doctor blade was used. The roller speed was about 2 cm / second. The slurry layer was then dried at a temperature of about 150 ° C and heat treated in a conventional oven at a temperature of about 350 ° C for about 5 minutes to form an electrically conductive composite film deposited on said release media. Said electrically conductive composite film was then peeled off the release liner to form a self-supporting electrically conductive composite film comprising PEKK and 2% by volume of carbon nanotubes. It had a resistivity of 6000 ohm / square.
    [0033] EXAMPLE 4 Preparation of an electrically conductive laminated composite structure according to the invention and prepared according to the process according to the invention A laminated composite structure was manufactured by manual preparation of a successive stack of an electrically conductive composite film. as obtained in Example 3, a layer of a fiber fabric, an electrically conductive composite film as obtained in Example 3, and a layer of fibers (ie 2-ply stack). [PEKK film-carbon nanotubes / fiber fabric layer] z), and by thermoforming the stack at a temperature of 350 ° C. and a pressure of 0.5 MPa, using the same press as that described in FIG. Example 2. When stacking 2 plies, the fiber layers are oriented in successive 0 ° and 45 ° orientations.
    [0034] The laminated composite structure obtained had a density of 1.662 and a conductivity of 0.1 S / m. COMPARATIVE EXAMPLE 5 Preparation of an Electrically Conductive Composite Film Not in Accordance with the Invention A self-supporting film of PEKK was prepared according to the process as described in Example 1 using a suspension of 2500 ml comprising 1000 g of thermoplastic polymer resin. Kepstan® 6003 and ethanol. The suspension had a viscosity of about 3 Pa.s. The suspension layer was applied to the release medium as described in Example 1, dried at a temperature of about 150 ° C, and heat-treated in a conventional oven at a temperature of about 350 ° C for about 5 minutes. This film does not form part of the invention since it does not comprise electrically conductive particles chosen from: a) graphene, carbon nanotubes, carbon nanofibers, and mixtures thereof; and b) the filamentous metal nanoparticles. It had a resistivity> 1 000 ohm / square. This self-supporting film, which is not in accordance with the invention, could also be obtained by forming in a hot press (ie melted) at a temperature of 350 ° C. and at a pressure of 0.5 MPa and using the same press. than that described in Example 2. COMPARATIVE EXAMPLE 6 Preparation of an electrically conductive laminated composite structure not in accordance with the invention A laminated composite structure was manufactured by manual preparation of a successive stack of a film such as obtained in Comparative Example 5, a layer of a fiber fabric, a film as obtained in Comparative Example 5, and a layer of fibers (ie 2-ply stack: [PEKK film fiber layer] 2), and by thermoforming the stack at a temperature of 350 ° C. and a pressure of 0.5 MPa, using the same press as that described in Example 2. 2-ply stack, the layers of fibers are oriented according to the successive orientations 0 ° and 45 °. The laminated composite structure obtained in accordance with the invention had a density of 1.655 and a conductivity of 10-12 S / m. Thus, this laminated composite structure, not forming part of the invention, has insufficient electrical conductivity and can not replace a metal structure. COMPARATIVE EXAMPLE 25 Preparation of an Electrically Conductive Composite Film Not in Accordance with the Invention A self-supporting film comprising PEKK (Kepstan® 6003 thermoplastic polymer resin) and 15% by volume of carbon black was prepared by press forming in the hot state (ie molten route) using the press as described in Example 2 at a temperature of 350 ° C and a pressure of 10 MPa. It had a resistivity of 200 ohm / square. This film is not part of the invention since it does not include electrically conductive particles selected from: a) graphene, carbon nanotubes, carbon nanofibers, and mixtures thereof; and b) threadlike metal nanoparticles. This same self-supporting film not in accordance with the invention could not be prepared according to a method similar to that described in Example 1 and in the invention (ie by preparing a suspension and then a coating suspension, drying and heat treatment). Indeed, the suspension included too much carbon black to form the suspension layer and said film, and if the amount of carbon black is less than 15% by volume, the conductivity of the film is not sufficient . COMPARATIVE EXAMPLE 8 Preparation of an electrically conductive laminated composite structure not according to the invention A laminated composite structure was manufactured by manual preparation of a successive stack of a film as obtained in Comparative Example 7, a layer of a fiber fabric, a film as obtained in Comparative Example 7, and a layer of fibers (ie 2-ply stack: [PEKK film-carbon black / fabric layer fibers] z), and by thermoforming the stack at a temperature of 350 ° C and a pressure of 18 MPa, using the same press as that described in Example 2. When stacking 2 plies, the layers of fibers are oriented in successive 0 ° and 45 ° orientations. The laminated composite structure obtained in accordance with the invention had a density of 1.703 and a conductivity of 1 S / m. This structure has sufficient electrical conductivity. However, it has been found to be very fragile and brittle, and therefore does not have adequate mechanical properties to be used.
    [0035] In conclusion, thanks to the electrically conductive film according to the invention comprising at least one thermoplastic resin and electrically conductive particles selected from a) graphene, carbon nanotubes, carbon nanofibers, and mixtures thereof; and b) metal nanoparticles, a laminated composite structure with both good electrical properties and good mechanics can be obtained. EXAMPLE 9 Preparation of an Electrically Conductive Composite Film According to the Invention and Prepared According to the Process According to the Invention A 2800 ml suspension comprising 250 g of silver nanowires in ethanol was prepared as in EXAMPLE 1 The suspension of silver nanowires was mixed with 1000 g of Fortron® 0205B4 thermoplastic polymer resin using mechanical stirring (100 rpm propeller) and ultrasound at a frequency of 50 kHz and a power of 25 W per pulse of 5 seconds. A homogeneous suspension comprising ethanol, PPS resin, and silver nanowires was thus obtained. The suspension had a viscosity of about 2 Pa.s. The suspension was applied to the Upilex or Cirex Si041WB® release media as in Example 1.
    [0036] The slurry layer was then dried at a temperature of about 150 ° C and heat-treated in a conventional oven at a temperature of about 310 ° C for about 5 minutes to form an electrically conductive composite film deposited on said release media. The electrically conductive composite film was then peeled off the release liner to form a self-supporting electrically conductive composite film comprising PPS and 3% by volume silver nanowires. It had a resistivity of 0.9 ohm / square.
    [0037] EXAMPLE 10 Preparation of an electrically conductive laminated composite structure according to the invention and prepared according to the process according to the invention A laminated composite structure was manufactured by manual preparation of a successive stack of an electrically conductive composite film. as obtained in Example 9, a layer of a fiber fabric, an electrically conductive composite film as obtained in Example 9, and a layer of fibers (ie 2-ply stack). [PPS film-silver nanowires / fiber fabric layer] 2), and by thermoforming the stack at a temperature of 310 ° C and a pressure of 0.5 MPa for 15 min, using the same press as that described in Example 2. During stacking 2 folds, the fiber layers are oriented in the 0 ° and 45 ° successive orientations.
    [0038] The laminated composite structure obtained had a density of 1.68 and a conductivity of 30 S / m.
    权利要求:
    Claims (17)
    [0001]
    REVENDICATIONS1. A process for preparing an electrically conductive composite film comprising at least one thermoplastic polymer resin and electrically conductive particles selected from: a) graphene, carbon nanotubes, carbon nanofibers, and mixtures thereof; and b) filamentary metal nanoparticles, said electrically conductive composite film optionally impregnating fibers, said method being characterized in that it comprises at least the following steps: 1) a step of preparing a suspension comprising a solvent and particles electrically conductive electrodes selected from: a) graphene, carbon nanotubes, carbon nanofibers, and mixtures thereof; and b) filamentary metal nanoparticles, said suspension comprising 0.06% to 0.5% by volume of said electrically conductive particles relative to the total volume of the suspension,
    [0002]
    2) a step of mixing a thermoplastic polymer resin powder of particle size less than or equal to 50 am with the suspension prepared in the preceding step to obtain a homogeneous suspension, said homogeneous suspension comprising from 7% to 20% by volume of said thermoplastic polymer resin with respect to the total volume of the suspension,
    [0003]
    3) a step of depositing the homogeneous suspension of the preceding step on a non-stick or fibrous support,
    [0004]
    4) a drying step, PP000483EN 38
    [0005]
    5) a heat treatment step at a temperature greater than or equal to the melting temperature of the thermoplastic polymer resin when it is in semicrystalline form or greater than or equal to its glass transition temperature when it is in the form of amorphous, in order to obtain an electrically conductive composite film deposited on said non-stick support or impregnating said fibrous support, and
    [0006]
    6) a step of removing the electrically conductive composite film from the support when the support is a non-stick support. 2. Method according to claim 1, characterized in that the solvent of step 1) is selected from hydrocarbon solvents, oxygenated solvents, chlorinated solvents, water, and mixtures thereof. 3. Method according to claim 1 or claim 2, characterized in that the electrically conductive particles are filiform metallic nanoparticles. 4. Process according to any one of the preceding claims, characterized in that the thermoplastic resin of step 2) is chosen from polyaryletherketones (PAEK) such as polyetheretherketones (PEEK), polyetherketonecetones (PEKK), polyetheretherketoneketones (PEEKK), polyetherketones (PEK), or polyetherketoneetherketoneketones (PEKEKK); Phenylene polysulfides (PPS); polyetherimides (PEI); polyethersulfones (PES); polysulfones (PS); polyamides (PA) such as nylon; polyimides (PI); polyamideimides (PAI); polycarbonates (PC); polyvinylidene fluorides (PVdF); copolymers of polyvinylidene fluoride and trifluoroethylene [P (VdF-TrFE)] or hexafluoropropene [P (VdF-HFP)]; and their mixtures. 5. Method according to any one of the preceding claims, characterized in that the suspension prepared in step 2) has a viscosity ranging from 1 Pa.s to 33 Pa.s. 6. Method according to any one of the preceding claims, characterized in that step 5) is carried out at a temperature ranging from 200 ° C to 400 ° C.PP000483EN 39
    [0007]
    7. Method according to any one of the preceding claims, characterized in that step 3) is performed according to the following substeps: 3a) a step of introducing the homogeneous suspension of step 2) into a reservoir comprising an injection nozzle in its lower part, and maintaining the suspension with mechanical stirring, 3b) a step of applying the suspension on a non-stick or fibrous support, with the aid of said injection nozzle and a squeegee located at the exit of the nozzle.
    [0008]
    8. Method according to any one of the preceding claims, characterized in that the support is a release-resistant support, and step 6) makes it possible to lead to a self-supporting electrically conductive composite film comprising at least one thermoplastic polymer resin and 1 % to 10% by volume of electrically conductive particles relative to the total volume of the electrically conductive composite film. 15
    [0009]
    9. Method according to any one of claims 1 to 6, characterized in that step 3) is performed according to the following substeps: 3a ') a step of introducing the homogeneous suspension of step 2) in a tank and its maintenance with mechanical stirring, 3b ') a step of immersing a fibrous support in the suspension. 20
    [0010]
    10. Method according to any one of claims 1 to 7 and 9, characterized in that the support is a fibrous support and step 5) leads to an electrically conductive composite prepreg comprising at least one thermoplastic polymer resin, 1% to 10% by volume of electrically conductive particles, and 10% to 70% by volume of fibers, based on the total volume of the electrically conductive composite prepreg.
    [0011]
    11. A method of manufacturing an electrically conductive laminated composite structure comprising at least one thermoplastic polymer resin, fibers, and electrically conductive particles selected from: a) graphene, carbon nanotubes, carbon nanofibers and their mixtures; and b) filamentary metal nanoparticles, said method being characterized in that it comprises one of the following two steps: i-1) a step of preparing a successive stack of at least one self-supporting electrically conductive composite film obtained according to the process as defined in claim 8, and at least one layer of fibers, OR i-2) a step of preparing a stack of at least two identical or different electrically conductive composite prepregs, obtained according to the process as defined in claim 10, and a thermoforming step ii).
    [0012]
    12. A method of manufacturing an electrically conductive laminated composite structure comprising at least one thermoplastic polymer resin, fibers, and electrically conductive particles selected from: a) graphene, carbon nanotubes, carbon nanofibers, and their mixtures; and b) filamentary metal nanoparticles, said method being characterized in that it comprises at least the following steps: A) a step of preparing at least one unit stack, comprising a first self-supporting electrically conductive composite film obtained according to the method as defined in claim 8, a layer of fibers, and optionally a second self-supporting electrically conductive composite film obtained by the process as defined in claim 8, B) a thermoforming step, so as to form a first filmPP000483EN 41 C) the repetition of steps A) and B), so as to form at least a second electrically conductive composite prepreg film, D) a step of preparing a stack of several electrically conductive composite prepreg films , identical or different, as obtained in steps B) and C), and E) a thermoforming step.
    [0013]
    13. Self-supporting electrically conductive composite film, characterized in that it comprises at least one thermoplastic polymer resin and from 1% to 10% by volume, based on the total volume of the self-supporting electrically conductive composite film, of electrically conductive particles selected from : a) graphene, carbon nanotubes, carbon nanofibers, and mixtures thereof; and b) filamentous metal nanoparticles.
    [0014]
    14. Electrically conductive composite prepreg, characterized in that it comprises at least one thermoplastic polymer resin, from 10% to 70% by volume of fibers, and from 1% to 10% by volume, relative to the total volume of the composite prepreg. electrically conductive, electrically conductive particles selected from: a) graphene, carbon nanotubes, carbon nanofibers, and mixtures thereof; and b) threadlike metal nanoparticles.
    [0015]
    15. An electrically conductive laminated composite structure, characterized in that it comprises any one of the following stacks: a successive stack of at least one self-supporting electrically conductive composite film obtained according to the method as defined in claim 8; or as defined in claim 13, and at least one layer of fibers, or - a stack of at least two electrically conductive composite prepregs, identical or different, obtained according to the method 5 as defined in claim 10, or as defined in claim 14, or - a stack of at least two identical or different unit stacks, comprising a first self-supporting electrically conductive composite film obtained according to the method as defined in claim 8 or as defined in the Claim 13, a fiber layer, and optionally a second electrically conductive composite film supported obtained according to the process as defined in claim 8 or as defined in claim 13.
    [0016]
    16. Use of an electrically conductive composite film obtained according to the process as defined in claim 8 or as defined in claim 13, for imparting electrical conductivity to a composite structure or prepreg composite, or improving their electrical conductivity.
    [0017]
    17. Use of an electrically conductive laminated composite structure obtained by the process as defined in claim 11 or 12 or as defined in claim 15, for replacing massive metal structures or for making support pieces or structures. of vehicle.
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    优先权:
    申请号 | 申请日 | 专利标题
    FR1457020A|FR3023746B1|2014-07-21|2014-07-21|PROCESS FOR PREPARING AN ELECTRICALLY CONDUCTIVE LAMINATED COMPOSITE STRUCTURE|FR1457020A| FR3023746B1|2014-07-21|2014-07-21|PROCESS FOR PREPARING AN ELECTRICALLY CONDUCTIVE LAMINATED COMPOSITE STRUCTURE|
    PCT/FR2015/051991| WO2016012708A1|2014-07-21|2015-07-20|Method for preparing an electrically conductive stratified composite structure|
    EP15759854.1A| EP3172269A1|2014-07-21|2015-07-20|Method for preparing an electrically conductive stratified composite structure|
    US15/327,566| US10535445B2|2014-07-21|2015-07-20|Method for preparing an electrically conductive stratified composite structure|
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