METHOD FOR MANUFACTURING A COMPOSITE PLATE

Abstract

The invention relates to a method (100) for manufacturing a composite plate (1), in which, during a first step (110), a succession of layers is deposited so as to form at least one laminate comprising at least one inner layer (10, 10a, 12, 12a) comprising carbon fiber scraps and a thermoplastic or thermosetting binder. During a second step, the laminate obtained at the end of step (110) is heated and the laminate is consolidated so as to allow the diffusion of the thermoplastic material as close as possible to the carbon fibers, and to bind the layers of the laminate to obtain a single-piece stack. Finally, it is allowed to cool to obtain a composite plate. The composite plate obtained can be directly used in a process for manufacturing industrial parts by thermoforming or thermocompression, which makes it possible to complete the industrial chain for exploiting carbon fiber scraps. Figure for the abstract: Fig. 5

Description

Title of the invention: METHOD FOR MANUFACTURING A COMPOSITE PLATE Technical field of the invention

[0001] The invention relates to the technical field of methods for manufacturing composite plates based on a material based on carbon fiber scraps for the manufacture of a part by thermoforming or thermocompression. Technical background

[0002] The consumption of carbon fibers has exploded over the last ten years. Production has adapted to meet the growing demand. Mainly used in composite structures, carbon fibers are widely used in the production of woven composite blades for new generation turbojets, particularly woven composite blades for dual-flow turbojets. During their manufacture, the layers of warp and weft yarns are released as the preform is created in order to achieve the different thicknesses of the blade. When the blade is released from the loom, a cutting operation of the warp and weft floats is carried out. The cut carbon yarns then become scraps from the weaving process.Thus, for the manufacture of woven composite blades alone, carbon fiber scraps represent a potential of several hundred tons / year spread across all production plants. In addition, these carbon fiber scraps have mechanical performance that is still intact because they have not been stressed. They can be used for the manufacture of new composite reinforcements.

[0003] However, until recently, these carbon fiber scraps were practically not recovered. Indeed, although reprocessing channels for such carbon fiber scraps have developed, the latter are saturated with demand, particularly from the automotive industry. Carbon fiber scraps are therefore not highly recovered (of the order of €1 / kg) and the outlets for the reuse of such fibers are still not very developed. They are mostly pyrolyzed and then ground into powder constituting fillers for primers, paints, or thermoplastic materials.

[0004] The applicant plans to recover carbon fiber scraps in order to set up a new sector. In this regard, research and development efforts have made it possible to develop a semi-finished recycling product based on carbon fiber scraps and a method for manufacturing such a product. The product is in the form of a roll of a non-woven strip comprising carbon fiber scraps having a length less than or equal to 100 mm and a binder ensuring the cohesion of the fibers between them and the holding of the strip. This semi-finished product as such cannot be used directly in a process of manufacturing a part by thermoforming or thermocompression and must be transformed to be able to be fully used. For example, after transformation, the product could be used for the manufacture of semi-structural parts. This type of part is widely used in the aeronautics field, in particular for making interiors, cabins and seats, or for panel-type assemblies. In addition, it could be more widely used in the transport sector (automobile, nautical) or in industrial manufacturing, for example the manufacture of molds.

[0005] However, to date and to the knowledge of the applicant, no measures aimed at exploiting this product have been undertaken. The invention therefore aims to provide a method for manufacturing a composite plate based on carbon fiber scraps for the manufacture of a part by thermoforming or thermocompression. Summary of the invention

[0006] The invention proposes for this purpose a method of manufacturing a composite plate, the method comprising the following steps: - place successively on a support:

[0007] - a first outer layer of a thermoplastic material,

[0008] - at least one inner layer, the inner layer or at least one of the layers interiors comprising carbon fiber scraps and a thermoplastic or thermosetting binder, and

[0009] - a second outer layer of the same thermoplastic material as the first outer layer so as to form at least one laminate,

[0010] - heating the laminate obtained at the end of the deposition step to a higher temperature or equal to the melting point of the thermoplastic material from which the first and second outer layers are made and consolidate the laminate so as to allow the diffusion of the thermoplastic material as close as possible to the carbon fibers, and to bond the layers of the laminate to obtain a single-piece stack, and

[0011] - let cool to obtain a composite plate.

[0012] The exploitation of semi-finished recycled products to produce a composite plate makes it possible to complete the recycling sector for carbon fiber scraps from production lines, and therefore allows the creation of a new sector for the recycling of such scraps. Indeed, at the input of the production line, there are scraps of carbon fibers at the end of their life. These are then revalued and are made available in the form of dry non-woven strips, through an intermediate step.

[0013] The invention uses these nonwovens in the or each inner layer of the laminate. formed during the deposition step. From this laminate, a composite plate is obtained after heating and consolidation, then cooling, which can be directly used in a manufacturing process for industrial parts, small and medium series, by thermoforming or thermocompression, thus completing the industrial chain for exploiting carbon fiber scraps.

[0014] Furthermore, the composite plate obtained by the process of the invention constitutes an interesting alternative to glass fiber-based composite materials, particularly in applications which require fiber-based composite materials having both good mechanical properties and low weight. These issues are of particular importance in the transport industry, particularly in the aeronautical field where fuel consumption is directly linked to the weight of the aircraft. The invention thus contributes to the decarbonization of the transport industry.

[0015] Finally, the invention makes it possible to aim for savings on the recycled materials produced, compared to “virgin materials” alternatives.

[0016] According to different characteristics of the invention which can be taken together or separately: • during the deposition step, at least two inner layers are deposited comprising carbon fiber scraps and a thermoplastic or thermosetting binder; • at least one of the inner layers is made of the same thermoplastic material as the first and second outer layers; • during the deposition step, each inner layer has a surface mass of between 100 g / m2 and 1000 g / m2, preferably between 200 g / m2 and 600 g / m2. • the thermoplastic material of said first and second outer layers is polyphenylene sulfide; • the thermoplastic material of said first and second outer layers is based on polyethersulfone; • the thermoplastic material of said first and second outer layers is based on polyphenylsulfone; • the thermoplastic material of said first and second outer layers is based on polycarbonate; • the binder is made of polyethylene; • the binder is made of polypropylene; • the binder is a polyethylene / polypropylene copolymer; • each of the outer layers has a thickness between 0.05 and 1 mm, preferably a thickness between 0.1 mm and 0.6 mm; • each of the inner layers has a thickness of between 0.05 mm and 1 mm, preferably between 0.1 mm and 0.6 mm; • during the heating and consolidation step, the laminate is heated to a temperature both greater than or equal to the melting point of the thermoplastic material from which the first and second outer layers are made and greater than or equal to the melting point of the thermoplastic material of the or each inner layer.

[0017] The invention further relates to a laminate for implementing the method as previously described. The laminate comprises a first outer layer of a thermoplastic material, a second outer layer of the same thermoplastic material as the first outer layer, and at least one inner layer located between the first and second outer layers, the inner layer or at least one of these inner layers comprising carbon fiber scraps, and a thermoplastic or thermosetting binder.

[0018] The invention also relates to a composite plate for the manufacture of a part by thermoforming or thermocompression, this plate being obtained by the method as previously mentioned and comprising a single-piece stack comprising at least one thermoplastic material, carbon fiber scraps, and a thermoplastic or thermosetting matrix in which the fibers are embedded.

[0019] It is understood that this matrix is ​​formed by the aforementioned outer layers as well as by the binder of the fibers.

[0020] The invention finally relates to a method of manufacturing a part, in particular for the aeronautical industry, by means of a composite plate as previously described, the method comprising a step of thermoforming or thermocompression of the composite plate. Brief description of the figures

[0021] Other objects, characteristics and advantages of the invention will appear more clearly in the description which follows, made with reference to the appended figures, in which:

[0022] - [Fig.1a] is a schematic representation of the manufacturing process of the composite plate according to a particular implementation of the invention,

[0023] - [Fig.lb] is a schematic representation of the manufacturing process of the composite plate according to another particular implementation of the invention,

[0024] - [Fig.2] illustrates carbon fiber scraps,

[0025] - [Fig.3] illustrates a composite plate according to the invention,

[0026] - [Fig.4] is a schematic representation of a laminate according to an example of rea use of the present invention,

[0027] - [Fig.5] is a schematic representation of a laminate according to another example of carrying out the present invention. Detailed description of the invention

[0028] The invention relates to a method 100 for manufacturing a composite plate 1. An example of a composite plate 1 is illustrated in [Fig.3].

[0029] The composite plate 1 is intended to be used for the manufacture of a part by thermoforming or thermocompression. The part to be manufactured is an industrial part, generally produced in small and medium series. The part can be used in non-structural or semi-structural applications, namely applications in which the part is able to support its own weight, while being able to support light external loads. In particular, in the aeronautical industry, such properties are sought after because they make it possible to obtain parts having a particularly interesting mechanical characteristic / on-board mass ratio.However, it is not only in the aeronautics industry that the invention can find outlets since this type of property is highly sought after in the transport industry, particularly in the automotive and nautical sectors, or in industrial manufacturing, for example in the manufacture of molds. For example, in the automotive sector, there is a real interest in reducing the weight of vehicles in order to simultaneously reduce their energy consumption.

[0030] A first step 110) of the method consists of successively depositing different layers on a support so as to form at least one laminate 2. In the context of the invention, the term “laminate” designates a stack of several layers (i.e. the first and second outer layers as well as the inner layers which will be described below) which are not agglomerated. The layers are said to be “non-agglomerated” because they are not bonded to each other, for example by means of a binder. A laminate therefore designates a stack of several layers which is not a single-piece stack. However, this does not exclude each layer of the laminate considered in isolation, namely the first outer layer considered in isolation, the second outer layer considered in isolation or any one of the inner layers considered in isolation, from itself being formed of several agglomerated layers.The first step 110) of the manufacturing method of the invention, called the deposition step, is therefore likely to vary depending on the nature, number and arrangement of the layers of the laminate 2.

[0031] According to an example of implementation of the method according to the invention illustrated in [Fig.1a], the following are successively deposited on a support S:

[0032] 111) a first outer layer 20 of a thermoplastic material,

[0033] 112) inner layers comprising at least one inner layer 10, 12 comprising carbon fiber scraps and a thermoplastic or thermosetting binder, and

[0034] 113) a second outer layer 22 of the same thermoplastic material as the first outer layer 20.

[0035] [Fig.4] illustrates a laminated example 2 obtained by implementing the deposition step 110) as previously mentioned, in particular with two inner layers 10, 12.

[0036] The arrangement of the layers within the laminate 2 gives it a “sandwich” structure. Indeed, as previously implemented, the deposition step 110) makes it possible to form a laminate 2 comprising a first outer layer 20 of a thermoplastic material, a second outer layer 22 of the same thermoplastic material as the first outer layer 20 and at least one inner layer located between the first and second outer layers 20, 22. In other words, the inner layer or layers are interposed between the first outer layer 20 and the second outer layer 22, which gives the laminate 2 the “sandwich” structure mentioned above.

[0037] The outer layers 20, 22 play a dual role. They ensure, before consolidation of the composite plate, the formation of an easily handled sandwich structure, and during consolidation good migration of the thermoplastic to the heart of the carbon fibers and the most intimate mixing possible.

[0038] As mentioned previously, at least one 10, 12 of the inner layers comprises carbon fiber scraps, and a thermoplastic or thermosetting binder. Preferably, the binder is compatible on the one hand with a method implemented to form the inner layers 10, 12, on the other hand with the thermoplastic material of the first and second outer layers. This ensures cohesion between the outer layers 20, 22 on the one hand and the inner layers 10, 12 comprising the carbon fiber scraps on the other hand.

[0039] The carbon fiber scraps, an example of which is illustrated in [Fig. 2], which are used in the inner layers 10, 12 of the composite plate 1 of the invention may result from the cutting of turbojet blade preforms. These preforms are produced by three-dimensional weaving of carbon fibers using a loom. That being said, they could also come from other processes. For example, the carbon fiber scraps could come from used wind turbine blades, however this would require a preliminary step of fiber / resin separation and preparation of these fiber scraps to ensure their implementation in a non-woven fabric of one of the inner layers.

[0040] The carbon fiber scraps can be obtained in the following manner. The blade of a turbojet blade is made from a fiber preform which is placed in a mold, and into which a polymerizable resin is injected. The fiber preform is obtained by cutting a preform made by three-dimensional weaving of carbon fibers using a weaving machine such as the Jacquard type, for example. Cutting the preform produces a preform that substantially has the shape of the blade to be obtained, and generates waste that is carbon fiber scraps. These scraps have a length less than or equal to 100 mm, and generally between 10 and 50 mm.

[0041] By way of non-limiting example, the inner layers 10, 12 comprising the carbon fiber scraps can be manufactured according to a carbon fiber recycling process comprising the following steps: 1. recover scraps of carbon fibers C, having a length typically less than or equal to 100 mm, 2. untangle, or even open, the carbon fibers and mix them with a thermoplastic or thermosetting binder, 3. use a dry air stream to disperse the fibers, 4. make a fiber mat comprising carbon fibers, air and the binding material, and 5. hot calendering the mattress to a temperature greater than or equal to the glass transition temperature of the thermoplastic or thermosetting binder, so as to produce an inner layer 10, 12 in the form of a roll of non-woven strip.

[0042] It should be noted that the invention does not relate to this manufacturing method, which is the subject of another application by the applicant. The inner layer(s) comprising the carbon fiber scraps are therefore in the form of carbon fibers impregnated with the thermoplastic or thermosetting binder, thus reinforcing the cohesion of the non-woven strip thus formed.

[0043] Then, during a second step 120) of the method according to the invention, the laminate is heated to a temperature greater than or equal to the melting point of the thermoplastic material from which the outer layers 20, 22 are made and the laminate is consolidated. During this step 120), called the heating and consolidation step, the outer thermoplastic layers 20, 22 will gradually melt, so as to allow: • the diffusion of the thermoplastic material as close as possible to the carbon fibers, • the bonding of the outer layers 20, 22 and inner layers 10, 12 until the formation of a single-piece stack in which the outer layers 20, 22 and inner layers become integral with each other to form a common matrix in which the fibers are embedded.

[0044] At the end of step 120) of heating and consolidation, the stratification carried out during of the deposition step 110) has thus “disappeared”, the composite plate 1 formed being made of a single-piece stack. The stack is called “single-piece” because the different layers from which it is formed are integral, that is to say that the outer layers 20, 22 and the inner layer(s) are no longer visible and form only one piece. A composite plate 1 comprising a stack of the aforementioned type, namely single-piece, is illustrated in [Fig.3].

[0045] At this stage, it should be noted that during the heating and consolidation step 120), the laminate may be heated to a temperature both greater than or equal to the melting point of the thermoplastic material from which the first and second outer layers are made, and greater than or equal to the melting point of the thermoplastic material of the or each inner layer. Indeed, if it is important in the first place that the first and second outer layers 20, 22 are capable of being transformed, that is to say that they are capable of being treated, it may be advantageous that the or each inner layer comprising carbon fiber scraps can also be transformed, and therefore that the thermoplastic material of the or each inner layer comprising carbon fiber scraps can be melted.That being said, let us specify that the melting point of the thermoplastic material of the or each inner layer can be indifferently lower or higher than the melting point of the thermoplastic material from which the first and second outer layers 20, 22 are made.

[0046] Advantageously, the heating and consolidation step 120) can be carried out under pressure. The press makes it possible to control the structure given to the composite plate 1.

[0047] Finally, the next step 130) consists of allowing the composite plate 1 to cool so that it acquires sufficient rigidity for its possible transport, and its use in a subsequent manufacturing process of an industrial part by thermoforming or thermocompression. Thus, during this step, called the cooling step, the hardness of the composite plate 1 increases. At the end of the cooling step 130), a homogeneous composite plate 1 is obtained.

[0048] A composite plate 1 is thus obtained made from the laminate as illustrated in [Fig.4]. The composite plate 1 made according to such an arrangement of layers can then be directly used in the manufacturing process by thermoforming or thermocompression. Indeed, these processes are conventionally implemented from a plate comprising a plastic material. In a process for manufacturing a part by thermoforming or by thermocompression, the composite plate 1 can be directly heated and then deformed so as to obtain an appearance part or a semi-structural part.

[0049] That being said, the manufacturing process of the composite plate 1 made from the laminate 2 as illustrated in [Fig.4] is only one example of implementation of the method according to the invention and other implementations can be envisaged.

[0050] According to another example of implementation of the manufacturing method according to the invention illustrated in [Fig.lb], during the deposition step 110), the following layers are successively deposited on a support S:

[0051] 111a) a first outer layer 20 of a thermoplastic material,

[0052] 112a) inner layers comprising at least one inner layer 10, 12 comprising carbon fiber scraps having a length less than or equal to 100 mm and a thermoplastic or thermosetting binder,

[0053] 113a) a second outer layer 22 of the same thermoplastic material as the first outer layer 20,

[0054] 114) a central inner layer 14 of the same nature as the inner layers filed in step 112a),

[0055] 111b) another first outer layer 20a of the same thermoplastic material that the first outer layer 20,

[0056] 112b) other inner layers comprising at least one layer 10a, 12a in inner layer comprising carbon fiber scraps, the other inner layers being of the same nature as the inner layers deposited in step 112a),

[0057] 113b) another second outer layer 22a of the same thermoplastic material than the first outer layer 20.

[0058] When step 110) is thus implemented, at least one laminate such as that illustrated in [Fig. 5] is obtained. The inner layers 10, 10a, 12, 12a, 14 can be manufactured according to the method described previously by implementing steps 1) to 5).

[0059] In practice, the laminate illustrated in [Fig. 5] consists of two laminates 2, as illustrated in [Fig. 4], which are separated by another inner layer 14, here identical to the other inner layers 10, 12. In other words, the laminate of [Fig. 5] corresponds to a complex laminate 2a comprising two “primary” laminates 2. Indeed, each laminate 2 comprises two inner layers and a first outer layer 20, 20a and a second outer layer 22, 22a. Each primary laminate 2 is therefore simply presented as the laminate 2 of the embodiment associated with [Fig. 4]. The first laminate 2 comprises the inner layers 10 and 10a and the first and second outer layers 20, 22 while the second laminate 2 comprises the inner layers 12 and 12a and the first and second outer layers 20a, 22a.

[0060] It should be noted that the addition of inner layers comprising carbon fiber scraps makes it possible, subject to appropriate impregnation with the thermoplastic binder, to increase the fiber volume ratio of the composite plate 1 produced and to improve its mechanical properties while offering a wider range of possibilities in the shapes of the part to be manufactured by thermoforming and thermocompression. Impregnation is appropriate when dry areas are avoided, i.e. areas where the carbon fibers are not or are only slightly impregnated with the thermoplastic binder. Indeed, a large number of dry areas, for example representing at least 20% of the volume of the inner layers, would harm the properties of the part to be manufactured by thermoforming or thermocompression.

[0061] In this respect, the ratio of the total number of outer layers 20, 22 to the total number of inner layers 10, 10a, 12, 12a, 14 on the other hand is preferably between 4:3 and 1:2, even more preferably between 1:1 and 3:4. It should be noted that the notation 4:3 means that there are 4 outer layers for 3 inner layers comprising the carbon fibers, the notation 1:2 means that there is 1 outer layer for 2 inner layers comprising the carbon fibers, etc. In all cases, there are always at least two outer layers to ensure the consolidation of the composite plate 1, as has been seen previously. For example, the ratio of 1 outer layer for 2 inner layers can be obtained by providing two outer layers and 4 inner layers.

[0062] The composite plate 1 thus obtained has significantly improved mechanical properties compared to the composite plate 1 of [Fig. 4]. It has improved mechanical properties compared to a composite plate 1 obtained from a laminate 2 which would not include the inner layer 14. Indeed, the inner layer 14 here plays the role of a reinforcing layer which makes it possible to avoid a concentration of thermoplastic in the central zone, according to the direction of stratification of the layers, of the composite plate 1 finally obtained.

[0063] If the composite plate 1 obtained by the method according to the first embodiment is more intended for industrial trim parts, that obtained by the method according to the second embodiment makes it possible to produce industrial parts requiring more enhanced mechanical properties and / or capable of supporting weights significantly higher than their own weight. In any event, other complex laminates 2a comprising three, or even four primary laminates 2 can be envisaged. Depending on the case, the deposition step 110) can be implemented by repeating the sub-steps 11 la) to 113 b) and by inserting another inner layer 14 between each primary laminate 2. Other variant embodiments within the reach of those skilled in the art can be implemented within the limits of the inventive concept at the basis of the present invention.

[0064] The steps 120) of heating and consolidation and 130) of cooling can advantageously be implemented in a manner similar to that described previously, only the nature of the laminate varying. Once the composite plate 1 has thus been manufactured, it can then be used in a method of manufacturing a part, in particular for the aeronautical industry, the method comprising a step of thermoforming or thermocompression of the composite plate 1. Such a method is also the subject of the invention.

[0065] The invention further relates to a composite plate 1 obtained by the manufacturing method as previously described. The composite plate 1 comprises a single-piece stack comprising at least one thermoplastic material, carbon fiber scraps, and a thermoplastic or thermosetting matrix in which the fibers are embedded.

[0066] Composite plates 1 respectively obtained from the laminate 2 according to the embodiment example of [Fig.4] and from the complex laminate 2a according to the embodiment example of [Fig.5] have been described in more detail previously. In the following, embodiment variants are described.

[0067] Advantageously, each of the outer layers 20, 22, 20a, 22a has a thickness of between 0.05 mm and 1 mm, preferably a thickness of between 0.1 mm and 0.6 mm, while, in parallel, each of the inner layers has a thickness of between 0.05 mm and 1 mm, preferably a thickness of between 0.1 mm and 0.6 mm.

[0068] The thickness of the outer layers 20, 22, 20a, 22a is chosen appropriately to allow both sufficient mechanical strength and adequate coating and impregnation of the inner layers of the composite plate 1.

[0069] The thickness of the inner layers makes it possible to meet the requirements in terms of mechanical strength but it can also be chosen according to the intended application. For example, thicknesses between 0.2 mm and 0.7 mm will be preferred for a composite plate 1 intended to be used as a lining in industrial parts while thicknesses between 0.7 mm and 1 mm will be chosen for applications in which the composite plate 1 is intended to be used as a support or even as a wall in industrial parts, this being in no way limiting and the choice of assembly will then depend on the functional specifications of the desired final composite plate.

[0070] In this regard, each of the inner layers has a surface mass advantageously between 100 g / m2 and 1000 g / m2. A surface mass of at least 100 g / m2 provides sufficient mechanical strength to the inner layers and their integration into a conventional production line for manufacturing industrial parts. A surface mass of at most 1000 g / m2 provides, subject to good impregnation, very good mechanical strength to the inner layers while having layers of an appropriate weight to produce a composite plate 1 intended to be used for the manufacture of parts having both excellent mechanical properties and low weight.

[0071] Preferably, each inner layer has a surface mass of between 200 g / m2 and 600 g / m2, which allows them to combine all the advantages seen previously. For comparison, the surface mass of a book page is generally between 135 g / m2 and 160 g / m2 while the surface mass of a bath mat is approximately 1000 g / m2.

[0072] Furthermore, as has been seen previously, the carbon fibers of the scraps used for the manufacture of the composite plate 1 according to the invention have a length less than or equal to 100 mm. Carbon fibers of such a dimension are obtained from scraps typically recovered from the production lines of turbojet blades as described previously. This being so, advantageously, the carbon fibers have a length of between 10 mm and 50 mm. Such dimensions considerably increase the mechanical strength of the inner layers made from these carbon fibers and, in addition, give them better conductivity.

[0073] The binder of the inner layers 10, 10a, 12, 12a is advantageously chemically compatible with the thermoplastic material of the first and second outer layers 20, 20a, 22, 22a, which makes it possible to reduce, or even considerably limit, the defects at the interfaces between the layers. This reduces the risk of porosities or other defects at the heart of the composite plate 1 over time.

[0074] Alternatively, only one or more inner layers 10, 10a, 12, 12a comprising the carbon fiber scraps comprises / comprise a binder compatible with the thermoplastic material of the first and second outer layers 20, 20a, 22, 22a. Other combinations within the reach of those skilled in the art may be envisaged without departing from the inventive concept underlying the present invention.

[0075] According to an exemplary implementation of the present invention, the first outer layer 20, 20a and the second outer layer 22, 22a may be based on polyphenylene sulfide (PPS). PPS is a thermoplastic material particularly suitable for thermoforming and thermocompression operations because it is fluid at forming temperatures, which facilitates the manufacture of industrial parts. It is therefore particularly suitable for use in the composite plate 1 according to the invention. That being said, other materials compatible with the method of manufacturing the composite plate may be used. As alternatives, the first outer layer 20, 20a and the second outer layer 22, 22a may be based on polyethersulfone (PESU) or polyphenylsulfone (PPSU) or polycarbonate (PC).

[0076] According to an exemplary implementation of the present invention, the binder of the inner layers 10, 10a, 12, 12a comprising the carbon fiber scraps is made of polyethylene (PE), polypropylene (PP) or based on a PE / PP copolymer.

[0077] Other thermoplastic or thermosetting binders may be considered, provided that they are compatible on the one hand with the process used to form the inner layers, and on the other hand with the thermoplastic used during the lamination. In this regard, it is preferable for the binder to be in the form of powder or fibers.

Claims

Claims

1. Method (100) for manufacturing a composite plate (1), the method comprising the following steps: > (110) successively depositing on a support (S): - (111, 111a, 111b) a first outer layer (20, 20a) of a thermoplastic material, - (112, 112a, 112b) at least one inner layer, the inner layer or at least one of the inner layers (10, 10a 12, 12a) comprising carbon fiber scraps and a thermoplastic or thermosetting binder, and - (113, 113a, 113b) a second outer layer (22, 22a) of the same thermoplastic material as the first outer layer (20, 20a) so as to form at least one laminate (2, 2a), > (120) heating the laminate obtained at the end of the deposition step at a temperature greater than or equal to the melting point of the thermoplastic material from which the first and second outer layers (20, 22, 20a, 22a) are made,and consolidate the laminate so as to allow the diffusion of the thermoplastic material as close as possible to the carbon fibers, and to bond the layers of the laminate to obtain a single-piece stack, and > (130) allow to cool to obtain a composite plate (1) the method (100) being characterized in that during the deposition step (110), each of the outer layers (20, 22, 20a, 22a) has a thickness of between 0.05 mm and 1 mm, preferably a thickness of between 0.1 mm and 0.6 mm, and each of the inner layers has a thickness of between 0.05 mm and 1 mm, preferably between 0.1 mm and 0.6 mm.,

2. Method (100) according to claim 1, in which, during the deposition step (110), at least two inner layers (10, 10a 12, 12a) are deposited comprising carbon fiber scraps and a thermoplastic or thermosetting binder.

3. The method (100) of claim 1 or 2, wherein at least one of the inner layers is made of the same thermoplastic material as the first and second outer layers (20, 20a, 22, 22a).

4. Method (100) according to any one of the preceding claims, wherein, during the deposition step (110), the or each inner layer (10, 10a 12, 12a) has a surface mass of between 100 g / m2 and 1000 g / m2, preferably between 200 g / m2 and 600 g / m2

5. A method (100) according to any preceding claim, wherein the thermoplastic material of said first and second outer layers (20, 20a, 22, 22a) is polyphenylene sulfide (PPS).

6. A method (100) according to any preceding claim, wherein the binder is polyethylene (PE), polypropylene (PP) or a polyethylene / polypropylene copolymer (PE-PP).

7. Laminate (2, 2a) for implementing the method according to any one of the preceding claims, the laminate (2) comprising: - a first outer layer (20, 20a) of a thermoplastic material, - a second outer layer (22, 22a) of the same thermoplastic material as the first outer layer (20, 20a), and - at least one inner layer located between the first and second outer layers, the inner layer or at least one of these inner layers (10, 10a 12, 12a) comprising carbon fiber scraps, and a thermoplastic or thermosetting binder, the laminate being characterized in that each of the outer layers (20, 22, 20a, 22a) has a thickness of between 0.05 mm and 1 mm, preferably a thickness of between 0.1 mm and 0.6 mm, and each of the inner layers has a thickness between 0.05 mm and 1 mm, preferably between 0.1 mm and 0.6 mm.

8. Composite plate (1) for the manufacture of a part by thermoforming or thermocompression, this plate being obtained by the method according to any one of claims 1 to 6 and comprising a single-piece stack comprising at least one thermoplastic material, carbon fiber scraps, and a thermoplastic or thermosetting matrix in which the fibers are embedded.

9. Method for manufacturing a part, in particular for the aeronautical industry, by means of a composite plate (1) according to claim 8, the method comprising a step of thermoforming or thermocompression of the composite plate (1).

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