EP4366937A1 - Knitted three-dimensional electroconductive mat for use as a lightning-resistant wall - Google Patents

Knitted three-dimensional electroconductive mat for use as a lightning-resistant wall

Info

Publication number
EP4366937A1
EP4366937A1 EP22744266.2A EP22744266A EP4366937A1 EP 4366937 A1 EP4366937 A1 EP 4366937A1 EP 22744266 A EP22744266 A EP 22744266A EP 4366937 A1 EP4366937 A1 EP 4366937A1
Authority
EP
European Patent Office
Prior art keywords
electrically conductive
knit
volume
composite material
yarn
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP22744266.2A
Other languages
German (de)
French (fr)
Inventor
Nicolas DUMONT
Gaëtan MAO
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Saint Gobain Performance Plastics France
Original Assignee
Saint Gobain Performance Plastics France
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Saint Gobain Performance Plastics France filed Critical Saint Gobain Performance Plastics France
Publication of EP4366937A1 publication Critical patent/EP4366937A1/en
Pending legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
    • B29C70/003—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts characterised by the matrix material, e.g. material composition or physical properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
    • B29C70/04—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts comprising reinforcements only, e.g. self-reinforcing plastics
    • B29C70/06—Fibrous reinforcements only
    • B29C70/10—Fibrous reinforcements only characterised by the structure of fibrous reinforcements, e.g. hollow fibres
    • B29C70/16—Fibrous reinforcements only characterised by the structure of fibrous reinforcements, e.g. hollow fibres using fibres of substantial or continuous length
    • B29C70/22—Fibrous reinforcements only characterised by the structure of fibrous reinforcements, e.g. hollow fibres using fibres of substantial or continuous length oriented in at least two directions forming a two dimensional structure
    • B29C70/222—Fibrous reinforcements only characterised by the structure of fibrous reinforcements, e.g. hollow fibres using fibres of substantial or continuous length oriented in at least two directions forming a two dimensional structure the structure being shaped to form a three dimensional configuration
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
    • B29C70/003—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts characterised by the matrix material, e.g. material composition or physical properties
    • B29C70/0035—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts characterised by the matrix material, e.g. material composition or physical properties comprising two or more matrix materials
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
    • B29C70/04—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts comprising reinforcements only, e.g. self-reinforcing plastics
    • B29C70/06—Fibrous reinforcements only
    • B29C70/08—Fibrous reinforcements only comprising combinations of different forms of fibrous reinforcements incorporated in matrix material, forming one or more layers, and with or without non-reinforced layers
    • B29C70/083—Combinations of continuous fibres or fibrous profiled structures oriented in one direction and reinforcements forming a two dimensional structure, e.g. mats
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
    • B29C70/04—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts comprising reinforcements only, e.g. self-reinforcing plastics
    • B29C70/06—Fibrous reinforcements only
    • B29C70/10—Fibrous reinforcements only characterised by the structure of fibrous reinforcements, e.g. hollow fibres
    • B29C70/16—Fibrous reinforcements only characterised by the structure of fibrous reinforcements, e.g. hollow fibres using fibres of substantial or continuous length
    • B29C70/20—Fibrous reinforcements only characterised by the structure of fibrous reinforcements, e.g. hollow fibres using fibres of substantial or continuous length oriented in a single direction, e.g. roofing or other parallel fibres
    • B29C70/205—Fibrous reinforcements only characterised by the structure of fibrous reinforcements, e.g. hollow fibres using fibres of substantial or continuous length oriented in a single direction, e.g. roofing or other parallel fibres the structure being shaped to form a three-dimensional configuration
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
    • B29C70/88—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts characterised primarily by possessing specific properties, e.g. electrically conductive or locally reinforced
    • B29C70/882—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts characterised primarily by possessing specific properties, e.g. electrically conductive or locally reinforced partly or totally electrically conductive, e.g. for EMI shielding
    • B29C70/885—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts characterised primarily by possessing specific properties, e.g. electrically conductive or locally reinforced partly or totally electrically conductive, e.g. for EMI shielding with incorporated metallic wires, nets, films or plates
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B64—AIRCRAFT; AVIATION; COSMONAUTICS
    • B64D—EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENT OR MOUNTING OF POWER PLANTS OR PROPULSION TRANSMISSIONS IN AIRCRAFT
    • B64D45/00—Aircraft indicators or protectors not otherwise provided for
    • B64D45/02—Lightning protectors; Static dischargers
    • D—TEXTILES; PAPER
    • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
    • D04B—KNITTING
    • D04B1/00—Weft knitting processes for the production of fabrics or articles not dependent on the use of particular machines; Fabrics or articles defined by such processes
    • D04B1/10—Patterned fabrics or articles
    • D04B1/12—Patterned fabrics or articles characterised by thread material
    • D04B1/123—Patterned fabrics or articles characterised by thread material with laid-in unlooped yarn, e.g. fleece fabrics
    • D—TEXTILES; PAPER
    • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
    • D04B—KNITTING
    • D04B1/00—Weft knitting processes for the production of fabrics or articles not dependent on the use of particular machines; Fabrics or articles defined by such processes
    • D04B1/14—Other fabrics or articles characterised primarily by the use of particular thread materials
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
    • B29B11/00—Making preforms
    • B29B11/14—Making preforms characterised by structure or composition
    • B29B11/16—Making preforms characterised by structure or composition comprising fillers or reinforcement
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
    • B29L2031/00—Other particular articles
    • B29L2031/30—Vehicles, e.g. ships or aircraft, or body parts thereof
    • D—TEXTILES; PAPER
    • D10—INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES
    • D10B—INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES
    • D10B2101/00—Inorganic fibres
    • D10B2101/20—Metallic fibres
    • D—TEXTILES; PAPER
    • D10—INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES
    • D10B—INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES
    • D10B2401/00—Physical properties
    • D10B2401/16—Physical properties antistatic; conductive
    • D—TEXTILES; PAPER
    • D10—INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES
    • D10B—INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES
    • D10B2403/00—Details of fabric structure established in the fabric forming process
    • D10B2403/02—Cross-sectional features
    • D10B2403/024—Fabric incorporating additional compounds
    • D10B2403/0241—Fabric incorporating additional compounds enhancing mechanical properties
    • D10B2403/02411—Fabric incorporating additional compounds enhancing mechanical properties with a single array of unbent yarn, e.g. unidirectional reinforcement fabrics
    • D—TEXTILES; PAPER
    • D10—INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES
    • D10B—INDEXING SCHEME ASSOCIATED WITH SUBLASSES OF SECTION D, RELATING TO TEXTILES
    • D10B2505/00—Industrial
    • D10B2505/02—Reinforcing materials; Prepregs

Definitions

  • the present invention relates to the walls / surfaces that must withstand lightning, to which they are likely to be exposed in a particular way. It therefore relates, for example, in this respect, to aircraft cabin parts.
  • This anti-lightning function is usually dealt with in carbon/epoxy composites in several different ways, not mutually exclusive, but possibly cumulative. Although it is a good conductor, carbon is damaged by the passage of lightning, which lowers the performance, particularly the mechanical performance of the composite.
  • a first way consists of adding a surface layer of weaving commonly referred to as "Ghent” fabric (copper / aluminum / bronze) (called in English “copper mesh” for example) generally of very low weight ( 50 - 300, in particular approximately 80 g/m 2 ), in expanded metal, in pierced foil (available in particular from the 3M Company), intended to distribute the electrical charges evenly over the entire surface.
  • a second way consists in the addition of a solid foil of width between 1 and 15 cm and thickness between 0.05 and 1 mm, which can have the function of collecting the charges of the copper fabric and of evacuate to the other rooms, bound for the rear of the aircraft.
  • a conductive layer is not possible, for example when the part must be radio-transparent as in the case of radomes, we use a diverter which can take the form of a tinsel. This has a lightning rod function, directly attracting lightning and evacuating the charges.
  • the foil is positioned at the junction between two parts, constituting a screwed equipotential strip, the screw performing electrical conduction between the two parts.
  • a third way consists in using composite materials with electrically conductive constituents in one of the two forms mentioned above, in thermosetting matrices.
  • fabrics pre-impregnated with polymeric material are particularly common, in particular fabrics pre-impregnated with polymeric material (or “prepreg”). These fabrics are traditionally formed of weft threads and warp threads arranged perpendicularly, and conventionally have a planar structure.
  • the fabrics are generally cut out and placed in a mold whose general shape corresponds to that of the part to be produced, the polymeric material (or resin) then being injected and polymerized in the mold in order in particular to give a rigid part.
  • the draping of woven reinforcements on a mold is a long and delicate operation.
  • thermosetting matrix in an electrically conductive composite has the disadvantage that the composite tends to absorb thermal energy, to degrade and to pierce.
  • the aim of the invention was to provide an anti-lightning or lightning-resistant part, the surface of which can be of complex three-dimensional geometry, of manufacture and implementation easily industrializable, not having the drawbacks described above.
  • the subject of the invention is a three-dimensional electrically conductive sheet consisting of an electrically conductive knit able to distribute the electrical charges homogeneously over its entire surface, characterized in that the knit comprises at least one continuous electrically conductive metallic yarn.
  • the electrically conductive knit is obtained from at least one continuous yarn of electrically conductive material (which may be mono- or multi-filament(s) and/or formed from discontinuous fibers bonded for example by twisting or wrapping, or any other textile process ).
  • the knitted fabric comprises one or more knitted or knitting yarns which may consist, from the point of view of their shape, of knit (loop) yarn(s), of filler yarn(s) (ripple), in float yarn(s) but not in weft yarn(s) (unidirectional).
  • Different knitting techniques in particular circular or rectilinear make it possible in particular to obtain knits forming a unitary piece, in 2D or in 3D, without seams.
  • thermoplastic polymeric material in the form of yarns or fibers mixed with the electroconductive yarns or fibers and to obtain a preform (intermediate/temporary form before the final) called "dry", containing both the material (s) electrically conductive (s) and the matrix.
  • the knitted web of the invention is therefore advantageously made in the shape of the final piece, including three-dimensional complex.
  • the invention provides ease of implementation and continuity of the electrically conductive fibers improving the electrical conductivity and the homogeneity of the distribution of electrical charges.
  • the knit comprises at least one electrically conductive continuous yarn, in particular one to four yarns, for example four copper yarns 0.1 mm in diameter.
  • the at least one electrically conductive wire is then metallic, such as copper, bronze, aluminum, brass, titanium, silver, gold or alloys thereof.
  • the knit then comprises a single continuous metal wire such as copper 0.01 to 1 mm in diameter.
  • the electrically conductive knit comprises at least one unidirectional electrically conductive UD yarn capable of displacing--evacuating the electrical charges in the direction of the UD yarn.
  • Each UD yarn is a weft yarn.
  • the electrically conductive UD wire(s) is (are) then metallic, such as copper, bronze or aluminum.
  • the metallic UD wires consist of a bundle of twelve copper wires of 0.02 to 2 mm in diameter, or have an electrical conductivity of the same order as that of such a bundle. These UD wires therefore have the capacity to evacuate a large quantity of electrical charges corresponding to a lightning strike, possibly repeated.
  • the electrically conductive knit comprises at least two different electrically conductive materials.
  • the electrically conductive knit comprises 0 to 40% by volume of one or more reinforcing yarn(s) such as carbon fibre, glass or aramid.
  • This or these reinforcing threads may for example be present in the form of one or more knit, filler and/or floated threads, and/or one or more weft threads added (s) in knitting in the form of unidirectional yarn(s).
  • Another object of the invention consists of a composite material characterized in that it comprises a sheet as described previously, and 40 to 95% by volume of thermoplastic and/or thermosetting polymer material.
  • the material composite (final product) is obtained from several constituents described in more detail below, among which a web described above comprising an optional addition of 0 to 60% by volume of thermoplastic and/or thermosetting polymer material, preferably exclusively thermoplastic (intermediate product).
  • the polymer material can be exclusively thermoplastic or exclusively thermosetting.
  • the thermoplastic polymer material may be integrated into the metallic knitted structure of the web in the form of one or more mesh, filler and/or float yarn(s) and/or one or more ) of added weft(s) in the knitting in the form of unidirectional yarn(s), for example.
  • thermoplastic polymers examples include polycarbonate (PC), polyetherimide (PEI), polypropylene (PP), polyamide (PA), poly(methyl methacrylate) (PMMA), poly(ethylene terephthalate) (PET) , poly(phenylene sulfide) (PPS), polyetheretherketone (PEEK), polyetherketoneketone (PEKK), alone or as mixtures or copolymers of several of them.
  • the thermosetting polymer material can be integrated into the electrically conductive knit of the web by subsequent impregnation.
  • thermosetting polymer material mention may be made of polyurethane (PU), epoxy resin, cyanate ester, phenolic resin, unsaturated polyester.
  • the polymer material advantageously comprises 100 to 5% by volume of thermoplastic material and 0 to 95% by volume of thermosetting resin.
  • the metallic knitted structure has a continuity of the fibers improving the electrical conductivity, the distribution and the evacuation of the charges, it heats up less under the effect of lightning, and it is possible to constitute the polymer matrix exclusively of thermoplastic material, in the absence of thermosetting resin.
  • An absence of thermoplastic material is possible, as already specified, but is not preferred. Indeed, a minor proportion of thermoplastic polymer in a predominantly thermosetting polymer material makes the polymer material weldable.
  • the thermosetting material is less likely to be pierced with regard to reduced heating under the effect of lightning mentioned above.
  • thermoplastic nature with a relatively high glass transition temperature Tg is sought, by using a thermoplastic polymer with a glass transition temperature greater than that of the thermosetting resin, in particular a Tg greater than 120°C, in order to guarantee heat resistance of the polymer matrix.
  • thermosetting polymer material An absence of thermosetting polymer material is possible. If thermosetting polymer is present, its proportion by volume is preferably greater than that of the thermoplastic polymer material.
  • the composite material of the invention is obtained by combining reinforcing fibers with a knitted electrically conductive sheet described above.
  • the reinforcing fibers can thus be combined in the form of woven yarns, mats, optionally themselves previously combined with thermoplastic polymer materials, and/or preimpregnated with thermosetting polymer materials.
  • the composite material is obtained by superimposing a knitted electrically conductive sheet according to the invention, and one or more knitted reinforcing thread(s).
  • Each knit of reinforcing yarn(s) can also be previously associated with thermoplastic polymer materials, and/or preimpregnated with thermosetting polymer materials.
  • the invention also relates to the use of a three-dimensional electrically conductive sheet or of a composite material described above to constitute the lightning-resistant wall of a land, water or air vehicle, or of a building, in particular a part of a train body, aircraft cabin or space vehicle.
  • a composite is produced by adding side by side a “Ghent” copper fabric (called “copper mesh”) with a weight equal to 80 g/m 2 , intended to distribute the electrical charges evenly over the entire the surface, and a copper foil 10 cm wide and a few tenths of a mm thick, which has the function of collecting the charges from the copper fabric and evacuating them towards the rear of the aircraft, then by superimposing on the assembly thus obtained, part of the surface of which is made up of Ghent copper fabric and the other part of the surface is made up of copper foil, a layer of woven carbon fibers preimpregnated with resin epoxy. This material is very difficult to drape, all the more so in complex three-dimensional form. This material was pierced and delaminated at the first lightning strike.
  • An electrically conductive knit is produced with one or more mesh, filler and/or float yarn(s) each consisting of a copper wire 0.1 mm in diameter and a thermoplastic polymer material integrated into the metallic knitted structure in the form of one or more knit, filler and/or float yarn(s) and/or one or more weft yarn(s) added to the knit in the form of yarn(s) unidirectional(s).
  • This knitting is directly made to any desired three-dimensional shape, regardless of its complexity. It presents a continuity of its conductive threads/fibers.
  • a three-dimensional electrically conductive knit is superimposed one or more reinforcing ply(ies) of the same three-dimensional geometry, and consisting of a fabric, a mat or a knit of reinforcing fibers such as carbon, glass or aramid, combined with a thermoplastic polymer material.
  • a first example of a reinforcing knit is a Kevlar® (aramid) and thermoplastic knit, that is to say having one or more mesh, filler and/or float yarn(s) consisting of aramid on the one hand, thermoplastic on the other hand, in which are inserted several unidirectional carbon yarns UD and several unidirectional thermoplastic yarns UD as weft yarns.
  • a second example of a reinforcing knit is a knit of glass and thermoplastic.
  • a third example of a reinforcing knit is a carbon and thermoplastic knit.
  • the composite material can be obtained in any desired three-dimensional complex shape, in one piece, with fiber continuity, after curing at a temperature above the Tg of the thermoplastic, and cooling.
  • Example 1 The electrically conductive knit of Example 1 is modified by inserting therein twelve parallel unidirectional UD copper threads 0.2 mm in diameter as the weft threads of the knit. On this three-dimensional electrically conductive knit, the same reinforcing fabrics, mats and knits as in Example 1 are superimposed. Examples 3 and 4
  • Examples 1 and 2 are reproduced, with the difference that the reinforcing fabrics, mats and knits are preimpregnated with liquid thermosetting resin in an amount such that the polymer material of the composite material constitutes at least 40% by volume, being distributed in a major part of thermosetting polymer and a minor part of thermoplastic polymer.
  • Examples 1 and 2 are reproduced, but without using one or more reinforcing plies. Instead of these, the reinforcing function is integrated into the copper knit, by means of one or more mesh, filler and/or float yarn(s) and/or one or more unidirectional UD yarns as weft yarns, made of reinforcing fibers such as carbon, glass or aramid.
  • Examples 5 and 6 are reproduced by impregnating the reinforced copper knit with liquid thermosetting resin in an amount such that the polymer material of the composite material constitutes at least 40% by volume, being divided into a major part of thermosetting polymer and a minor part of thermoplastic polymer.
  • the function of uniform charge distribution over the entire surface by the copper knit is very effective: the paint was burned evenly despite at least four lightning strikes without destroying the copper knit, which still conducts the current evenly electric even after these impacts.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Composite Materials (AREA)
  • Textile Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Mathematical Physics (AREA)
  • Aviation & Aerospace Engineering (AREA)
  • Knitting Of Fabric (AREA)
  • Laminated Bodies (AREA)
  • Reinforced Plastic Materials (AREA)
  • Woven Fabrics (AREA)

Abstract

The invention relates to a three-dimensional electroconductive mat formed of an electroconductive knitted fabric capable of homogeneously distributing electrical charges over the entire surface thereof, characterised in that the knitted fabric comprises at least one electroconductive metal filament yarn; a composite material comprising such a mat, and 40 to 95% by volume of a thermoplastic and/or thermosetting polymer material; and the use of such a three-dimensional electroconductive mat or such a composite material as a lightning-resistant wall.

Description

Description Description
Titre de l'invention : Nappe électroconductrice tridimensionnelle tricotée pour constituer une paroi résistant à la foudre Title of the invention: Knitted three-dimensional electrically conductive sheet to form a wall resistant to lightning
La présente invention a trait aux parois / surfaces devant résister à la foudre, à laquelle elles sont susceptibles d’être exposées de manière particulière. Elle est donc par exemple relative, à cet égard, aux pièces de carlingues d’avion. The present invention relates to the walls / surfaces that must withstand lightning, to which they are likely to be exposed in a particular way. It therefore relates, for example, in this respect, to aircraft cabin parts.
Les avantages des composites notamment carbone / époxy ne sont plus à démontrer par rapport à l’aluminium en raison de leur performance mécanique et de leur légèreté. Toutefois la réalisation de pièces exposées à la foudre en composite nécessite de garantir leur résistance à l’impact de foudre, et leur capacité à écouler les charges électriques le long du fuselage d’avion, par exemple, sans endommagement des pièces, alors que la conductivité de l’aluminium est suffisante pour exercer cette fonction. The advantages of composites, in particular carbon/epoxy, are well established compared to aluminum due to their mechanical performance and their lightness. However, the production of composite parts exposed to lightning requires guaranteeing their resistance to lightning impact, and their ability to flow electric charges along the aircraft fuselage, for example, without damaging the parts, whereas the conductivity of aluminum is sufficient to perform this function.
Cette fonction anti-foudre est généralement traitée dans les composites carbone / époxy de plusieurs manières différentes, ne s’excluant pas les unes les autres, mais éventuellement cumulatives. Bien qu’étant un bon conducteur, le carbone est endommagé lors du passage de la foudre, ce qui fait chuter les performances notamment mécaniques du composite. This anti-lightning function is usually dealt with in carbon/epoxy composites in several different ways, not mutually exclusive, but possibly cumulative. Although it is a good conductor, carbon is damaged by the passage of lightning, which lowers the performance, particularly the mechanical performance of the composite.
Une première manière consiste en l’adjonction d’une couche de surface en tissage communément désignée sous les termes de tissu « gantois » (cuivre / aluminium / bronze) (appelé en anglais «copper mesh » par exemple) généralement de très faible grammage (50 - 300, notamment environ 80 g/m2), en métal déployé, en clinquant percé (disponible notamment chez la Société 3M), destinée à répartir les charges électriques de manière homogène sur toute la surface. A first way consists of adding a surface layer of weaving commonly referred to as "Ghent" fabric (copper / aluminum / bronze) (called in English "copper mesh" for example) generally of very low weight ( 50 - 300, in particular approximately 80 g/m 2 ), in expanded metal, in pierced foil (available in particular from the 3M Company), intended to distribute the electrical charges evenly over the entire surface.
Une seconde manière consiste en l’adjonction d’un clinquant plein de largeur comprise entre 1 et 15 cm et d’épaisseur comprise entre 0,05 et 1 mm, qui peut avoir pour fonction de collecter les charges du tissu de cuivre et de les évacuer vers les autres pièces, à destination de l’arrière de l’avion. Lorsque l’utilisation d’une couche conductrice n’est pas possible, par exemple lorsque la pièce doit être radio-transparente comme dans le cas des radômes, on utilise un diverter qui peut prendre la forme d’un clinquant. Celui-ci a une fonction de paratonnerre, en attirant directement la foudre et en évacuant les charges. Dans certaines réalisations, le clinquant est positionné à la jonction entre deux pièces, constituant une bande d’équipotentiel vissée, la vis réalisant une conduction électrique entre les deux pièces. A second way consists in the addition of a solid foil of width between 1 and 15 cm and thickness between 0.05 and 1 mm, which can have the function of collecting the charges of the copper fabric and of evacuate to the other rooms, bound for the rear of the aircraft. When the use of a conductive layer is not possible, for example when the part must be radio-transparent as in the case of radomes, we use a diverter which can take the form of a tinsel. This has a lightning rod function, directly attracting lightning and evacuating the charges. In some embodiments, the foil is positioned at the junction between two parts, constituting a screwed equipotential strip, the screw performing electrical conduction between the two parts.
Une troisième manière consiste à employer des matériaux composites à constituants électroconducteurs sous l’une des deux formes citées précédemment, en matrices thermodurcissables. A third way consists in using composite materials with electrically conductive constituents in one of the two forms mentioned above, in thermosetting matrices.
Ces solutions ne donnent pas satisfaction. These solutions are not satisfactory.
Tout d’abord, l’utilisation de tissus est particulièrement courante, en particulier de tissus pré-imprégnés de matière polymérique (ou « prépreg »). Ces tissus sont traditionnellement formés de fils de trame et de fils de chaîne disposés perpendiculairement, et présentent classiquement une structure plane. Afin d’obtenir un produit en trois dimensions (ou 3D), les tissus sont généralement découpés et disposées dans un moule dont la forme générale correspond à celle de la pièce à réaliser, la matière polymérique (ou résine) étant ensuite injectée et polymérisée dans le moule afin notamment de donner une pièce rigide. Le drapage de renforts tissés sur un moule est une opération longue est délicate. Elle nécessite l’utilisation de plusieurs couches de « prépeg » qui doivent être découpées et disposées judicieusement suivant la forme du moule pour assurer une épaisseur suffisante tout en évitant trop de recouvrement. La découpe des tissus métalliques pré-imprégnés ou non implique des chutes de produit pouvant représenter 30% de matière. Les tissus électroconducteurs métalliques sont difficiles à draper d’autant plus que la forme de la pièce est tridimensionnelle. First of all, the use of fabrics is particularly common, in particular fabrics pre-impregnated with polymeric material (or “prepreg”). These fabrics are traditionally formed of weft threads and warp threads arranged perpendicularly, and conventionally have a planar structure. In order to obtain a three-dimensional (or 3D) product, the fabrics are generally cut out and placed in a mold whose general shape corresponds to that of the part to be produced, the polymeric material (or resin) then being injected and polymerized in the mold in order in particular to give a rigid part. The draping of woven reinforcements on a mold is a long and delicate operation. It requires the use of several layers of "prepeg" which must be cut and arranged judiciously according to the shape of the mold to ensure sufficient thickness while avoiding too much overlap. The cutting of metallic fabrics, pre-impregnated or not, involves scraps of product that can represent 30% of material. Metallic electrically conductive fabrics are difficult to drape especially since the shape of the piece is three-dimensional.
Plusieurs pièces de tissus métalliques peuvent être cousues ensemble pour réaliser des surfaces complexes : leur mise en œuvre est complexe, et la continuité des fibres n’est alors pas assurée, diminuant l’homogénéité de la répartition des charges électriques sur toute la surface. Several pieces of metal fabric can be sewn together to create complex surfaces: their implementation is complex, and the continuity of the fibers is therefore not ensured, reducing the homogeneity of the distribution of electrical charges over the entire surface.
D’autre part, l’utilisation d’un clinquant plein nécessite une découpe relativement complexe, et la production de chutes à mettre au rebut. Enfin, l’emploi d’une matrice thermodurcissable dans un composite électroconducteur présente l’inconvénient que le composite a tendance à absorber l’énergie thermique, à se dégrader et se percer. On the other hand, the use of a solid foil requires relatively complex cutting, and the production of offcuts to be discarded. Finally, the use of a thermosetting matrix in an electrically conductive composite has the disadvantage that the composite tends to absorb thermal energy, to degrade and to pierce.
Le document US 2020/290296 A1 décrit une nappe électroconductrice tridimensionnelle constituée d’un tricot électroconducteur en carbone, qui est trop résistif pour pouvoir constituer une paroi résistant à la foudre. Document US 2020/290296 A1 describes a three-dimensional electrically conductive sheet consisting of an electrically conductive carbon knit, which is too resistive to be able to constitute a wall resistant to lightning.
Le document US 4 755 904 A décrit une nappe électroconductrice constituée d’un tricot électroconducteur ; cette nappe est plane et non tridimensionnelle. Document US 4,755,904 A describes an electrically conductive sheet consisting of an electrically conductive knit; this web is flat and not three-dimensional.
L’invention a eu pour but de mettre à disposition une pièce anti-foudre, ou résistant à la foudre, dont la surface peut être de géométrie complexe tridimensionnelle, de fabrication et mise en œuvre aisément industrialisables, ne présentant pas les inconvénients décrits précédemment. A cette fin, l’invention a pour objet une nappe électroconductrice tridimensionnelle constituée d’un tricot électroconducteur apte à répartir les charges électriques de manière homogène sur toute sa surface, caractérisée en ce que le tricot comprend au moins un fil continu électroconducteur métallique. The aim of the invention was to provide an anti-lightning or lightning-resistant part, the surface of which can be of complex three-dimensional geometry, of manufacture and implementation easily industrializable, not having the drawbacks described above. To this end, the subject of the invention is a three-dimensional electrically conductive sheet consisting of an electrically conductive knit able to distribute the electrical charges homogeneously over its entire surface, characterized in that the knit comprises at least one continuous electrically conductive metallic yarn.
Le tricot électroconducteur est obtenu à partir d’au moins un fil continu en matériau électroconducteur (qui peut être mono-ou multi-filament(s) et/ou formé de fibres discontinues liées par exemple par retordage ou guipage, ou tout autre procédé textile). Au sens de l’invention, on convient que le tricot comprend un ou plusieurs fils tricotés ou de tricotage pouvant consister, du point de vue de leur forme, en fil(s) de maille (boucle), en fil(s) de charge (ondulation), en fil(s) flotté(s) mais non en fil(s) de trame (unidirectionnel). Différentes techniques de tricotage (en particulier circulaire ou rectiligne) permettent notamment d’obtenir des tricots formant une pièce unitaire, en 2 D ou en 3D, sans couture. Du point de vue de la technologie, le tricot électroconducteur peut être obtenu par la technologie trame : il s’agit de la direction privilégiée du fil par analogie au tissu nonobstant sa forme, le sens trame étant le sens rangée par opposition au sens chaîne qui est le sens colonne. Ces structures tricotées présentent de nombreux avantages par rapport aux structures tissées. En effet, outre la possibilité de réaliser d’emblée une structure en 3D en une seule pièce sans couture, le tricotage peut se faire le cas échéant à partir d’une seule bobine de fil pour le fil de maille, alors que les tissus nécessitent toujours plusieurs bobines distinctes. En outre, alors que le drapage de structures tissées sur un moule est une opération longue et délicate, notamment lorsque la forme recherchée est complexe, nécessitant l’utilisation de plusieurs couches de tissus qui doivent être découpés (avec des chutes de produit pouvant représenter 30% de matière) et disposés judicieusement suivant la forme du moule pour assurer une épaisseur suffisante tout en évitant trop de recouvrement et nécessitant d'ajouter des pièces de renfort localement pour assurer la reprise de la résistance mécanique, cette reprise étant imparfaite car les fibres ne sont pas continues, le tricotage en 2D ou 3D permet pour sa part de réaliser un produit complexe, pouvant le cas échéant être directement drapé sur une forme en 2D ou en 3D et assurant la continuité des fils dans tout le produit obtenu, le tricot, présentant déjà une forme adaptée pour obtenir le produit recherché, n’ayant par exemple besoin que d’être positionné autour d’un support souple tel qu’une vessie en silicone, l’ensemble étant alors déposé dans un moule pour réaliser sous vide la consolidation permettant d’obtenir le produit fini. The electrically conductive knit is obtained from at least one continuous yarn of electrically conductive material (which may be mono- or multi-filament(s) and/or formed from discontinuous fibers bonded for example by twisting or wrapping, or any other textile process ). Within the meaning of the invention, it is agreed that the knitted fabric comprises one or more knitted or knitting yarns which may consist, from the point of view of their shape, of knit (loop) yarn(s), of filler yarn(s) (ripple), in float yarn(s) but not in weft yarn(s) (unidirectional). Different knitting techniques (in particular circular or rectilinear) make it possible in particular to obtain knits forming a unitary piece, in 2D or in 3D, without seams. From the point of view of technology, electrically conductive knitting can be obtained by weft technology: this is the preferred direction of the yarn by analogy to the fabric regardless of its shape, the weft direction being the row direction as opposed to the warp direction which is the column direction. These knitted structures have many advantages over woven structures. In fact, in addition to the possibility of immediately creating a 3D structure in a single seamless piece, knitting can be done if necessary from a single spool of yarn for the knit yarn, whereas the fabrics require always several separate coils. In addition, while the draping of woven structures on a mold is a long and delicate operation, especially when the desired shape is complex, requiring the use of several layers of fabric that must be cut (with product scraps that can represent 30 % of material) and arranged judiciously according to the shape of the mold to ensure sufficient thickness while avoiding too much overlap and requiring the addition of reinforcement parts locally to ensure the recovery of the mechanical resistance, this recovery being imperfect because the fibers do not are not continuous, 2D or 3D knitting makes it possible to produce a complex product, which can, if necessary, be directly draped over a 2D or 3D shape and ensuring the continuity of the yarns throughout the product obtained, the knit, already having a shape adapted to obtain the desired product, needing for example only to be positioned around a flexible support such as a bladder silicone, the assembly then being placed in a mold to achieve vacuum consolidation to obtain the finished product.
De plus, les structures tissées, lorsqu’elles sont pré-imprégnées de matière polymérique (par exemple gélifiée) les plus couramment utilisées doivent en outre être manipulées délicatement, ces structures étant collantes lorsque le film de protection est enlevé, et ne se conservant que durant une période limitée à température ambiante. A contrario, le tricotage permet d’intégrer le cas échéant la matière polymérique thermoplastique sous forme de fils ou fibres mélangés avec les fils ou fibres électroconduc(teur)(trice)s et d’obtenir une préforme (forme intermédiaire/temporaire avant la forme définitive) dite « sèche », contenant à la fois le(s) matériau (x) électroconducteur(s) et la matrice. In addition, the most commonly used woven structures, when they are pre-impregnated with polymeric material (for example gelled), must also be handled delicately, these structures being sticky when the protective film is removed, and only keeping for a limited period at room temperature. Conversely, knitting makes it possible to integrate, where appropriate, the thermoplastic polymeric material in the form of yarns or fibers mixed with the electroconductive yarns or fibers and to obtain a preform (intermediate/temporary form before the final) called "dry", containing both the material (s) electrically conductive (s) and the matrix.
La nappe tricotée de l’invention est donc avantageusement réalisée dans la forme de la pièce finale, y compris complexe tridimensionnelle. L’invention apporte une facilité de mise en œuvre et une continuité des fibres électroconductrices améliorant la conductivité électrique et l’homogénéité de la répartition des charges électriques. The knitted web of the invention is therefore advantageously made in the shape of the final piece, including three-dimensional complex. The invention provides ease of implementation and continuity of the electrically conductive fibers improving the electrical conductivity and the homogeneity of the distribution of electrical charges.
De préférence, le tricot comprend au moins un fil continu électroconducteur, notamment un à quatre fils, par exemple quatre fils de cuivre de 0,1 mm de diamètre. Preferably, the knit comprises at least one electrically conductive continuous yarn, in particular one to four yarns, for example four copper yarns 0.1 mm in diameter.
De préférence, le au moins un fil électroconducteur est alors métallique, tel qu’en cuivre, bronze, aluminium, laiton, titane, argent, or ou alliages de ceux-ci. Preferably, the at least one electrically conductive wire is then metallic, such as copper, bronze, aluminum, brass, titanium, silver, gold or alloys thereof.
De préférence, le tricot comprend alors un seul fil continu métallique tel qu’en cuivre de 0,01 à 1 mm de diamètre. Preferably, the knit then comprises a single continuous metal wire such as copper 0.01 to 1 mm in diameter.
De préférence, le tricot électroconducteur comprend au moins un fil unidirectionnel UD électroconducteur apte à déplacer - évacuer les charges électriques dans la direction du fil UD. Chaque fil UD est un fil de trame. Preferably, the electrically conductive knit comprises at least one unidirectional electrically conductive UD yarn capable of displacing--evacuating the electrical charges in the direction of the UD yarn. Each UD yarn is a weft yarn.
De préférence, le ou les fil(s) UD électroconducteur(s) est (sont) alors métallique(s), tel(s) qu’en cuivre, bronze ou aluminium. Preferably, the electrically conductive UD wire(s) is (are) then metallic, such as copper, bronze or aluminum.
De préférence, les fils UD métalliques sont constitués d’un faisceau de douze fils de cuivre de 0,02 à 2 mm de diamètre, ou ont une conductivité électrique du même ordre que celle d’un tel faisceau. Ces fils UD ont par conséquent la capacité à évacuer une quantité importante de charges électriques correspondant à un impact de foudre, éventuellement répété. Preferably, the metallic UD wires consist of a bundle of twelve copper wires of 0.02 to 2 mm in diameter, or have an electrical conductivity of the same order as that of such a bundle. These UD wires therefore have the capacity to evacuate a large quantity of electrical charges corresponding to a lightning strike, possibly repeated.
Dans une alternative intéressante, le tricot électroconducteur comprend au moins deux matériaux électroconducteurs différents. In an interesting alternative, the electrically conductive knit comprises at least two different electrically conductive materials.
Dans une autre alternative intéressante, le tricot électroconducteur comprend 0 à 40 % en volume d’un ou plusieurs fil(s) de renfort tel(s) qu’en fibre de carbone, verre ou aramide. Ce ou ces fils de renfort peut ou peuvent par exemple être présent(s) sous la forme d’un ou plusieurs fils de maille, de charge et/ou flotté(s), et/ou d’un ou plusieurs fils de trame ajouté(s) dans le tricot sous forme de fil(s) unidirectionnel(s). In another interesting alternative, the electrically conductive knit comprises 0 to 40% by volume of one or more reinforcing yarn(s) such as carbon fibre, glass or aramid. This or these reinforcing threads may for example be present in the form of one or more knit, filler and/or floated threads, and/or one or more weft threads added (s) in knitting in the form of unidirectional yarn(s).
Un autre objet de l’invention consiste en un matériau composite caractérisé en ce qu’il comprend une nappe telle que décrite précédemment, et 40 à 95 % en volume de matériau polymère thermoplastique et/ou thermodurcissable. Le matériau composite (produit final) est obtenu à partir de plusieurs constituants décrits plus en détails dans la suite, parmi lesquels une nappe décrite précédemment comprenant un ajout facultatif de 0 à 60 % en volume de matériau polymère thermoplastique et/ou thermodurcissable, de préférence exclusivement thermoplastique (produit intermédiaire). Le matériau polymère peut être exclusivement thermoplastique ou exclusivement thermodurcissable. Le matériau polymère thermoplastique peut être intégré dans la structure tricotée métallique de la nappe sous la forme d’un ou plusieurs fil(s) de maille, de charge et/ou flotté(s) et/ou d’un ou plusieurs fil(s) de trame ajouté(s) dans le tricot sous forme de fil(s) unidirectionnel(s), par exemple. Comme exemples de polymères thermoplastiques, on peut citer les polycarbonate (PC), polyétherimide (PEI), polypropylène (PP), polyamide (PA), poly(méthacrylate de méthyle) (PMMA), poly(téréphtalate d'éthylène) (PET), poly(sulfure de phénylène) (PPS), polyétheréthercétone (PEEK), polyéthercétonecétone (PEKK), seuls ou en mélanges ou copolymères de plusieurs d’entre eux. Le matériau polymère thermodurcissable peut être intégré dans le tricot électroconducteur de la nappe par une imprégnation ultérieure. Comme matériau polymère thermodurcissable, on peut citer les polyuréthane (PU), résine époxy, ester de cyanate, résine phénolique, polyester insaturé. Another object of the invention consists of a composite material characterized in that it comprises a sheet as described previously, and 40 to 95% by volume of thermoplastic and/or thermosetting polymer material. The material composite (final product) is obtained from several constituents described in more detail below, among which a web described above comprising an optional addition of 0 to 60% by volume of thermoplastic and/or thermosetting polymer material, preferably exclusively thermoplastic (intermediate product). The polymer material can be exclusively thermoplastic or exclusively thermosetting. The thermoplastic polymer material may be integrated into the metallic knitted structure of the web in the form of one or more mesh, filler and/or float yarn(s) and/or one or more ) of added weft(s) in the knitting in the form of unidirectional yarn(s), for example. Examples of thermoplastic polymers include polycarbonate (PC), polyetherimide (PEI), polypropylene (PP), polyamide (PA), poly(methyl methacrylate) (PMMA), poly(ethylene terephthalate) (PET) , poly(phenylene sulfide) (PPS), polyetheretherketone (PEEK), polyetherketoneketone (PEKK), alone or as mixtures or copolymers of several of them. The thermosetting polymer material can be integrated into the electrically conductive knit of the web by subsequent impregnation. As thermosetting polymer material, mention may be made of polyurethane (PU), epoxy resin, cyanate ester, phenolic resin, unsaturated polyester.
Dans ce matériau composite, le matériau polymère comprend avantageusement 100 à 5 % en volume de matériau thermoplastique et 0 à 95 % en volume de résine thermodurcissable. Comme la structure tricotée métallique présente une continuité des fibres améliorant la conductivité électrique, la répartition et l’évacuation des charges, elle chauffe moins sous l’effet de la foudre, et il est possible de constituer la matrice polymère exclusivement de matériau thermoplastique, en l’absence de résine thermodurcissable. Une absence de matériau thermoplastique est possible, comme déjà précisé, mais n’est pas préférée. En effet, une proportion mineure de polymère thermoplastique dans un matériau polymère majoritairement thermodurcissable rend le matériau polymère soudable. D’autre part, le matériau thermodurcissable risque moins de se percer eu égard à échauffement diminué sous l’effet de la foudre mentionné ci-dessus. On recherche de préférence une nature thermoplastique à relativement haute température de transition vitreuse Tg, en employant un polymère thermoplastique de température de transition vitreuse supérieure à celle de la résine thermodurcissable, en particulier une Tg supérieure à 120 °C, afin de garantir une résistance à la chaleur de la matrice polymère. In this composite material, the polymer material advantageously comprises 100 to 5% by volume of thermoplastic material and 0 to 95% by volume of thermosetting resin. As the metallic knitted structure has a continuity of the fibers improving the electrical conductivity, the distribution and the evacuation of the charges, it heats up less under the effect of lightning, and it is possible to constitute the polymer matrix exclusively of thermoplastic material, in the absence of thermosetting resin. An absence of thermoplastic material is possible, as already specified, but is not preferred. Indeed, a minor proportion of thermoplastic polymer in a predominantly thermosetting polymer material makes the polymer material weldable. On the other hand, the thermosetting material is less likely to be pierced with regard to reduced heating under the effect of lightning mentioned above. Preferably, a thermoplastic nature with a relatively high glass transition temperature Tg is sought, by using a thermoplastic polymer with a glass transition temperature greater than that of the thermosetting resin, in particular a Tg greater than 120°C, in order to guarantee heat resistance of the polymer matrix.
Une absence de matériau polymère thermodurcissable est possible. Si du polymère thermodurcissable est présent, sa proportion en volume est de préférence supérieure à celle du matériau polymère thermoplastique. An absence of thermosetting polymer material is possible. If thermosetting polymer is present, its proportion by volume is preferably greater than that of the thermoplastic polymer material.
De préférence, le matériau composite de l’invention est obtenu en associant des fibres de renfort à une nappe électroconductrice tricotée décrite précédemment. Les fibres de renfort peuvent être ainsi associées sous forme de fils tissés, de mats, éventuellement eux-mêmes préalablement associés à des matériaux polymères thermoplastiques, et/ou préimprégnés de matériaux polymères thermodurcissables. Preferably, the composite material of the invention is obtained by combining reinforcing fibers with a knitted electrically conductive sheet described above. The reinforcing fibers can thus be combined in the form of woven yarns, mats, optionally themselves previously combined with thermoplastic polymer materials, and/or preimpregnated with thermosetting polymer materials.
Cependant, dans une variante préférée de cette réalisation, le matériau composite est obtenu en superposant une nappe électroconductrice tricotée selon l’invention, et un ou plusieurs tricots de fil(s) de renfort. Chaque tricot de fil(s) de renfort peut également être préalablement associé à des matériaux polymères thermoplastiques, et/ou préimprégné de matériaux polymères thermodurcissables. However, in a preferred variant of this embodiment, the composite material is obtained by superimposing a knitted electrically conductive sheet according to the invention, and one or more knitted reinforcing thread(s). Each knit of reinforcing yarn(s) can also be previously associated with thermoplastic polymer materials, and/or preimpregnated with thermosetting polymer materials.
L’invention a également pour objet l’utilisation d’une nappe électroconductrice tridimensionnelle ou d’un matériau composite décrit(e) ci-dessus pour constituer la paroi résistant à la foudre d’un véhicule terrestre, aquatique ou aérien, ou d’un bâtiment, en particulier une partie de carrosserie de train, carlingue d’avion ou véhicule spatial. The invention also relates to the use of a three-dimensional electrically conductive sheet or of a composite material described above to constitute the lightning-resistant wall of a land, water or air vehicle, or of a building, in particular a part of a train body, aircraft cabin or space vehicle.
L’invention sera mieux comprise à la lumière des exemples suivants. The invention will be better understood in the light of the following examples.
Contre-exemple 1 Counterexample 1
On réalise un composite par l’adjonction côte à côte d’un tissu « gantois » de cuivre (appelé en anglais «copper mesh ») de grammage égal à 80 g/m2, destiné à répartir les charges électriques de manière homogène sur toute la surface, et d’un clinquant de cuivre de 10 cm de largeur et quelques dixièmes de mm d’épaisseur, qui a pour fonction de collecter les charges du tissu de cuivre et de les évacuer vers l’arrière de l’avion, puis par la superposition à l’ensemble ainsi obtenu, dont une partie de la surface est constituée du tissu gantois de cuivre et l’autre partie de la surface est constituée du clinquant de cuivre, d’une nappe de fibres tissées de carbone préimprégnées de résine époxy. Ce matériau est très difficile à draper, d’autant plus en forme complexe tridimensionnelle. Ce matériau a été percé et s’est délaminé au premier impact de foudre. A composite is produced by adding side by side a “Ghent” copper fabric (called “copper mesh”) with a weight equal to 80 g/m 2 , intended to distribute the electrical charges evenly over the entire the surface, and a copper foil 10 cm wide and a few tenths of a mm thick, which has the function of collecting the charges from the copper fabric and evacuating them towards the rear of the aircraft, then by superimposing on the assembly thus obtained, part of the surface of which is made up of Ghent copper fabric and the other part of the surface is made up of copper foil, a layer of woven carbon fibers preimpregnated with resin epoxy. This material is very difficult to drape, all the more so in complex three-dimensional form. This material was pierced and delaminated at the first lightning strike.
Exemple 1 Example 1
On réalise un tricot électroconducteur avec un ou plusieurs fil(s) de maille, de charge et/ou flotté(s) consistant chacun en un fil de cuivre de 0,1 mm de diamètre et un matériau polymère thermoplastique intégré dans la structure tricotée métallique sous la forme d’un ou plusieurs fil(s) de maille, de charge et/ou flotté(s) et/ou un ou plusieurs fil(s) de trame ajouté(s) dans le tricot sous forme de fil(s) unidirectionnel(s). Ce tricot est directement réalisé à la forme voulue quelconque tridimensionnelle, quelle que soit sa complexité. Il présente une continuité de ses fils / fibres conducteur(trice)s. An electrically conductive knit is produced with one or more mesh, filler and/or float yarn(s) each consisting of a copper wire 0.1 mm in diameter and a thermoplastic polymer material integrated into the metallic knitted structure in the form of one or more knit, filler and/or float yarn(s) and/or one or more weft yarn(s) added to the knit in the form of yarn(s) unidirectional(s). This knitting is directly made to any desired three-dimensional shape, regardless of its complexity. It presents a continuity of its conductive threads/fibers.
A ce tricot électroconducteur tridimensionnel, on superpose une ou plusieurs nappe(s) de renfort de même géométrie tridimensionnelle, et constituée(s) d’un tissu, d’un mat ou d’un tricot de fibres de renfort telles que carbone, verre ou aramide, associé à un matériau polymère thermoplastique. Un premier exemple de tricot de renfort est un tricot de kevlar® (aramide) et de thermoplastique, c’est-à-dire ayant un ou plusieurs fil(s) de maille, de charge et/ou flotté(s) constitués d’aramide d’une part, de thermoplastique d’autre part, dans lequel sont insérés plusieurs fils de carbone unidirectionnels UD et plusieurs fils thermoplastiques unidirectionnels UD comme fils de trame. Un deuxième exemple de tricot de renfort est un tricot de verre et de thermoplastique. Un troisième exemple de tricot de renfort est un tricot de carbone et de thermoplastique. On this three-dimensional electrically conductive knit is superimposed one or more reinforcing ply(ies) of the same three-dimensional geometry, and consisting of a fabric, a mat or a knit of reinforcing fibers such as carbon, glass or aramid, combined with a thermoplastic polymer material. A first example of a reinforcing knit is a Kevlar® (aramid) and thermoplastic knit, that is to say having one or more mesh, filler and/or float yarn(s) consisting of aramid on the one hand, thermoplastic on the other hand, in which are inserted several unidirectional carbon yarns UD and several unidirectional thermoplastic yarns UD as weft yarns. A second example of a reinforcing knit is a knit of glass and thermoplastic. A third example of a reinforcing knit is a carbon and thermoplastic knit.
Le matériau composite peut être obtenu à une forme quelconque complexe tridimensionnelle désirée, d’un seul tenant, avec continuité des fibres, après cuisson à une température supérieure à la Tg du thermoplastique, et refroidissement. The composite material can be obtained in any desired three-dimensional complex shape, in one piece, with fiber continuity, after curing at a temperature above the Tg of the thermoplastic, and cooling.
Exemple 2 Example 2
On modifie le tricot électroconducteur de l’exemple 1 en y insérant douze fils unidirectionnels UD parallèles de cuivre de 0,2 mm de diamètre comme fils de trame du tricot. A ce tricot électroconducteur tridimensionnel, on superpose les mêmes tissus, mats et tricots de renfort qu’à l’exemple 1 . Exemples 3 et 4 The electrically conductive knit of Example 1 is modified by inserting therein twelve parallel unidirectional UD copper threads 0.2 mm in diameter as the weft threads of the knit. On this three-dimensional electrically conductive knit, the same reinforcing fabrics, mats and knits as in Example 1 are superimposed. Examples 3 and 4
On reproduit les exemples 1 et 2, à la différence près que les tissus, mats et tricots de renfort sont préimprégnés de résine thermodurcissable liquide en quantité telle que le matériau polymère du matériau composite en constitue au moins 40 % en volume, se répartissant en une majeure partie de polymère thermodurcissable et une partie mineure de polymère thermoplastique. Examples 1 and 2 are reproduced, with the difference that the reinforcing fabrics, mats and knits are preimpregnated with liquid thermosetting resin in an amount such that the polymer material of the composite material constitutes at least 40% by volume, being distributed in a major part of thermosetting polymer and a minor part of thermoplastic polymer.
Exemples 5 et 6 Examples 5 and 6
On reproduit les exemples 1 et 2, mais sans utiliser une ou plusieurs nappes de renfort. Au lieu de celles-ci, on intègre la fonction de renfort dans le tricot de cuivre, au moyen d’un ou plusieurs fil(s) de maille, de charge et/ou flotté(s) et/ou d’un ou plusieurs fils unidirectionnels UD comme fils de trame, constitués de fibres de renfort telles que carbone, verre ou aramide. Examples 1 and 2 are reproduced, but without using one or more reinforcing plies. Instead of these, the reinforcing function is integrated into the copper knit, by means of one or more mesh, filler and/or float yarn(s) and/or one or more unidirectional UD yarns as weft yarns, made of reinforcing fibers such as carbon, glass or aramid.
Exemples 7 et 8 Examples 7 and 8
On reproduit les exemples 5 et 6 en imprégnant le tricot de cuivre renforcé de résine thermodurcissable liquide en quantité telle que le matériau polymère du matériau composite en constitue au moins 40 % en volume, se répartissant en une majeure partie de polymère thermodurcissable et une partie mineure de polymère thermoplastique. Examples 5 and 6 are reproduced by impregnating the reinforced copper knit with liquid thermosetting resin in an amount such that the polymer material of the composite material constitutes at least 40% by volume, being divided into a major part of thermosetting polymer and a minor part of thermoplastic polymer.
La fonction de répartition homogène des charges sur toute la surface par le tricot de cuivre est très efficace : la peinture a été brûlée de manière homogène malgré au moins quatre impacts de foudre sans destruction du tricot de cuivre, qui conduit toujours de manière homogène le courant électrique même après ces impacts. The function of uniform charge distribution over the entire surface by the copper knit is very effective: the paint was burned evenly despite at least four lightning strikes without destroying the copper knit, which still conducts the current evenly electric even after these impacts.
La fonction de déplacement / évacuation des charges par les fils unidirectionnels UD de cuivre de section et conductivité électrique relativement importantes reste très efficace, les fils UD ayant été suffisamment conducteurs pour drainer les charges sans brûlure de la peinture, donc sans échauffement. The displacement/discharge function of the charges by the unidirectional UD copper wires of relatively large section and electrical conductivity remains very effective, the UD wires having been sufficiently conductive to drain the charges without burning the paint, therefore without overheating.
La fonction mécanique assurée par les fibres / fils de renfort des tissus, mats et tricots de renfort reste intègre après les tirs répétés sans dégradation structurelle par l’onde de choc qui a été absorbée par le matériau très tenace sans percement de la matière, alors que le composite du contre-exemple 1 a été percé et s’est délaminé dès le premier impact de foudre. The mechanical function ensured by the reinforcing fibres/threads of the reinforcing fabrics, mats and knits remains intact after repeated shots without structural degradation by the shock wave which has been absorbed by the very tenacious material without piercing the material, so that the composite of counter-example 1 was pierced and delaminated from the first lightning strike.

Claims

Revendications Claims
[Revendication 1] jNappe électroconductrice tridimensionnelle constituée d’un tricot électroconducteur apte à répartir les charges électriques de manière homogène sur toute sa surface, caractérisée en ce que le tricot comprend au moins un fil continu électroconducteur métallique. [Claim 1] Three-dimensional electrically conductive sheet consisting of an electrically conductive knit suitable for distributing electrical charges evenly over its entire surface, characterized in that the knit comprises at least one continuous electrically conductive metal yarn.
[Revendication 2] Nappe selon la revendication 1 , caractérisée en ce que le au moins un fil électroconducteur est en cuivre, bronze, aluminium, laiton, titane, argent, or ou alliages de ceux-ci. [Claim 2] Sheet according to claim 1, characterized in that the at least one electrically conductive wire is made of copper, bronze, aluminum, brass, titanium, silver, gold or alloys thereof.
[Revendication 3] Nappe selon la revendication 2, caractérisée en ce que le tricot comprend un seul fil continu métallique tel qu’en cuivre de 0,01 à 1 mm de diamètre. [Claim 3] Tablecloth according to claim 2, characterized in that the knit comprises a single continuous metal wire such as copper of 0.01 to 1 mm in diameter.
[Revendication 4] Nappe selon l’une des revendications 1 ou 2, caractérisée en ce que le tricot électroconducteur comprend au moins un fil unidirectionnel UD électroconducteur apte à déplacer - évacuer les charges électriques dans la direction du fil UD. [Claim 4] Tablecloth according to one of Claims 1 or 2, characterized in that the electrically conductive knit comprises at least one unidirectional electrically conductive UD yarn capable of displacing - evacuating the electrical charges in the direction of the UD yarn.
[Revendication 5] Nappe selon la revendication 4, caractérisée en ce que le ou les fil(s) UD électroconducteur(s) est (sont) métallique(s), tel(s) qu’en cuivre, bronze ou aluminium. [Claim 5] Sheet according to claim 4, characterized in that the electrically conductive UD wire(s) is (are) metallic, such as copper, bronze or aluminium.
[Revendication 6] Nappe selon la revendication 5, caractérisée en ce que les fils UD métalliques sont constitués d’un faisceau de douze fils de cuivre de 0,02 à 2 mm de diamètre, ou ont une conductivité électrique du même ordre que celle d’un tel faisceau. [Claim 6] Sheet according to claim 5, characterized in that the metallic UD son consist of a bundle of twelve copper son 0.02 to 2 mm in diameter, or have an electrical conductivity of the same order as that of such a beam.
[Revendication 7] Nappe selon l’une des revendications précédentes, caractérisée en ce que le tricot électroconducteur comprend au moins deux matériaux électroconducteurs différents. [Claim 7] Sheet according to one of the preceding claims, characterized in that the electrically conductive knit comprises at least two different electrically conductive materials.
[Revendication 8] Nappe selon l’une des revendications précédentes, caractérisée en ce que le tricot électroconducteur comprend 0 à 40 % en volume d’un ou plusieurs fil(s) de renfort tel(s) qu’en fibre de carbone, verre ou aramide. [Claim 8] Sheet according to one of the preceding claims, characterized in that the electrically conductive knit comprises 0 to 40% by volume of one or more reinforcing thread(s) such as carbon fibre, glass or aramid.
[Revendication 9] Matériau composite, caractérisé en ce qu’il comprend une nappe selon l’une des revendications précédentes, et 40 à 95 % en volume de matériau polymère thermoplastique et/ou thermodurcissable. [Claim 9] Composite material, characterized in that it comprises a web according to one of the preceding claims, and 40 to 95% by volume of thermoplastic and/or thermosetting polymer material.
[Revendication 10] Matériau composite selon la revendication 9, caractérisé en ce que le matériau polymère comprend 100 à 5 % en volume de matériau thermoplastique et 0 à 95 % en volume de résine thermodurcissable. [Claim 10] Composite material according to claim 9, characterized in that the polymeric material comprises 100 to 5% by volume of thermoplastic material and 0 to 95% by volume of thermosetting resin.
[Revendication 11] Matériau composite selon la revendication 10, caractérisé en ce que la proportion en volume de matériau polymère thermodurcissable est supérieure à la proportion en volume de matériau polymère thermoplastique. [Claim 11] Composite material according to Claim 10, characterized in that the proportion by volume of thermosetting polymer material is greater than the proportion by volume of thermoplastic polymer material.
[Revendication 12] Matériau composite selon l’une des revendications 9 à 11 , caractérisé en ce qu’il est obtenu en associant des fibres de renfort à une nappe selon l’une des revendications 1 à 8. [Claim 12] Composite material according to one of Claims 9 to 11, characterized in that it is obtained by combining reinforcing fibers with a sheet according to one of Claims 1 to 8.
[Revendication 13] Matériau composite selon la revendication 12, caractérisé en ce qu’il est obtenu en superposant une nappe selon l’une des revendications 1 à 8, et un ou plusieurs tricots de fil(s) de renfort. [Claim 13] Composite material according to Claim 12, characterized in that it is obtained by superimposing a ply according to one of Claims 1 to 8, and one or more knits of reinforcing yarn(s).
[Revendication 14] Utilisation d’une nappe électroconductrice tridimensionnelle selon l’une des revendications 1 à 8 ou d’un matériau composite selon l’une des revendications 9 à 13 pour constituer la paroi résistant à la foudre d’un véhicule terrestre, aquatique ou aérien, ou d’un bâtiment, en particulier une partie de carrosserie de train, carlingue d’avion ou véhicule spatial. ! [Claim 14] Use of a three-dimensional electrically conductive sheet according to one of Claims 1 to 8 or of a composite material according to one of Claims 9 to 13 to constitute the lightning-resistant wall of a terrestrial, aquatic vehicle or aerial, or of a building, in particular a part of the body of a train, aircraft cabin or space vehicle. !
EP22744266.2A 2021-07-06 2022-06-22 Knitted three-dimensional electroconductive mat for use as a lightning-resistant wall Pending EP4366937A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR2107293A FR3124973A1 (en) 2021-07-06 2021-07-06 Knitted three-dimensional electrically conductive sheet to form a wall resistant to lightning
PCT/FR2022/051221 WO2023281180A1 (en) 2021-07-06 2022-06-22 Knitted three-dimensional electroconductive mat for use as a lightning-resistant wall

Publications (1)

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EP4366937A1 true EP4366937A1 (en) 2024-05-15

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Application Number Title Priority Date Filing Date
EP22744266.2A Pending EP4366937A1 (en) 2021-07-06 2022-06-22 Knitted three-dimensional electroconductive mat for use as a lightning-resistant wall

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EP (1) EP4366937A1 (en)
KR (1) KR20240029021A (en)
CN (1) CN117615901A (en)
CA (1) CA3223958A1 (en)
FR (1) FR3124973A1 (en)
IL (1) IL309672A (en)
WO (1) WO2023281180A1 (en)

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4755904A (en) * 1986-06-06 1988-07-05 The Boeing Company Lightning protection system for conductive composite material structure
ES2214343T3 (en) * 1999-12-15 2004-09-16 N.V. Bekaert S.A. COMPOSITE FABRIC TILE.
DE202014009963U1 (en) * 2014-12-16 2015-01-15 Tec-Knit Creativcenter Für Technische Textilien Gmbh Knit with unidirectional fibers
FR3093667B1 (en) * 2019-03-11 2021-04-23 Saint Gobain Performance Plastics France PREPARATION OF A COMPOSITE MATERIAL PRODUCT CONTAINING ZONES OF DIFFERENT FUNCTIONALITIES

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FR3124973A1 (en) 2023-01-13
KR20240029021A (en) 2024-03-05
CN117615901A (en) 2024-02-27
IL309672A (en) 2024-02-01
CA3223958A1 (en) 2023-01-12

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