Overmolded composite structure

Abstract

The invention relates to an overmolded composite structure comprising: i) a first component C1 comprising at least one fibrous material and a matrix resin composition, said matrix resin composition comprising at least one reactive thermoplastic polymer, and optionally a chain extender or chain limiter, said thermoplastic polymer having a number-average molecular weight Mn between 3,000 and 35,000 g / mol, preferably between 5,000 and 20,000 g / mol, preferably between 5,000 and 15,000 g / mol, preferably between 5,000 and 10,000 g / mol; and ii) a second component C2 comprising an overmolding resin composition, the first component C1 having at least one surface S, and component C2 adhering to component C1 on at least part of surface S.

Description

[0001] Overmolded composite structure

[0002] Field of invention

[0003] The present invention relates to an overmolded structure comprising a composite and a thermoplastic polymer overmolded component.

[0004] Technical background

[0005] Composite materials are increasingly being developed in various fields such as automotive, aeronautics, sports equipment, etc. Hybrid structures (composite / metal, composite / polymer, or metal / polymer, etc.) are developing and are also seen as an interesting alternative not only to lighten and strengthen structures, but also to provide multiple functions to the part thus manufactured. There is in particular a desire to replace the metal parts of certain parts to reduce the weight of said parts and reduce production costs. Such composites are notably used for the manufacture of overmolded composite structures where a component is overmolded on at least part of a surface of the composite.

[0006] Thus, many players in the automotive and aeronautics sectors have developed manufacturing processes for improved parts.

[0007] For example, localized reinforcements based on composites (carbon fibers + thermoplastic polymer) are placed in an automotive part injection mold to locally and intelligently reinforce the injected part (car door for example). This lightens the part and strengthens it in its preferred direction(s) of stress.

[0008] In addition to these areas of use, other players in cutting-edge technological and performance fields have sought to appropriate these new transformation technologies and adapt them to their needs.

[0009] For several years now, there have been numerous developments in sports, leisure, and electronics. For example, more and more manufacturers of running and athletic shoes, as well as cycling and other competitive and leisure sports, are incorporating composite reinforcement elements into their shoes. These composites can provide improved and diverse performance features to their products, such as greater durability, higher performance (especially energy return), and weight reduction, for example.

[0010] These composites generally come in the form of plates which are manufactured beforehand by traditional processes and are generally based on carbon fibers impregnated with thermosetting resins (epoxies) or in rare cases thermoplastic (acrylics, PC, PP). These composite reinforcements can then be integrated into the finished products using different processes, in particular bonding to an existing support. This bonding is essential and ensures cohesion between the composite part and the overmolded polymer / elastomer which are generally not of the same chemical nature. It also allows the composite to be held in place for the following stages of manufacturing the finished product.Without cohesion, the composite and the overmolded product will only have limited performance over time and / or will not meet certain essential performance criteria upon leaving the production line (dimensions and positioning in the finished product, finish appearance, optical quality, thermal or electrical conductivity / insulation, transfer of mechanical load from the overmolded to the composite and vice versa, premature rupture of the stressed interface, etc.).

[0011] Bonding solutions, to be as compatible as possible with the elements to be assembled, are generally based on reactive thermosetting resins (cold or hot) and / or solvent-based. They are therefore not perfectly compatible with the two components of the overmolded composite if they are of a different chemical nature. Furthermore, they are not depolymerizable in a possible disassembly and recycling phase of the product at the end of its life.

[0012] To overcome these inconveniences, alternative solutions have been proposed:

[0013] - the preparation of the surface state of the composites to make them rougher / textured. Thus the specific contact surface is larger and therefore potentially of better quality between the composite and the adhesive. However, there remains a chemical / physical incompatibility which limits the performance and / or the duration of use with maintenance of the performance the use of thermoplastic adhesives instead of thermosetting adhesives. However, the application of these adhesives is often more complicated, and very generally it is only compatible with one of the two components to be assembled

[0014] - surface treatment to functionalize one or both surfaces to make them more compatible. However, this step, which generally consists of plasma treatment (cold or hot), is expensive and the surface treatment has a short lifespan (a few hours at best).

[0015] Overmolded composite structures are known from US2012108122 that do not require the use of adhesive. However, before the overmolding step, the composite is heated close to its melting temperature, which can damage the physical properties of the composite, in particular its degree of consolidation, which influences the mechanical performance of the final part. There is therefore a real need to provide a composite material compatible with the overmolding polymer layer that makes it possible to dispense with any additional adhesion primer between the composite and the overmolded component. There is also a real need to provide a composite material compatible with the overmolding polymer layer and allowing good adhesion between the composite material and the overmolding layer, and in particular making it possible to obtain a peel strength greater than 50N / cm, preferably greater than or equal to 70 N / cm and particularly preferably greater than or equal to 100 N / cm.

[0016] Summary of the invention

[0017] The invention relates firstly to an overmolded composite structure comprising: i) a first component (C1) comprising at least one fibrous material and a matrix resin composition, said matrix resin composition comprising at least one reactive thermoplastic polymer, and optionally a chain extender and / or chain limiter and / or catalyst and / or one or more additives, said thermoplastic polymer has a number-average molecular weight Mn of between 3000 and 35000 g / mol, preferably between 5000 and 20000 g / mol, preferably between 5000 and 15000 g / mol, preferentially between 5000 and 10000 g / mol; and ii) a second component (C2) comprising an overmolding resin composition, said first component (C1) comprising at least one surface (S) and said component (C2) adhering to said component (C1) on at least a portion of said surface (S).

[0018] Preferably, said at least one reactive thermoplastic polymer is a polyamide, polycarbonate or polymethacrylate, preferably polyamide, and optionally comprises epoxy type groups, preferably said reactive thermoplastic polymer is a polyamide.

[0019] Preferably, said at least one reactive thermoplastic polymer is chosen from:

[0020] An aliphatic polyamide selected from polyamide 6 (PA-6), polyamide 11 (PA-11), polyamide 12 (PA-12), polyamide 66 (PA-66), polyamide 46 (PA-46), polyamide 610 (PA-610), polyamide 612 (PA-612), polyamide 1010 (PA-1010), polyamide 1012 (PA-1012), polyamide 11 / 1010 and polyamide 12 / 1010, or a mixture thereof or a copolyamide thereof, and polyetheramide or polyetheresteramide (PEBA) copolymers (or polyamide block and polyether block copolymer), or a semi-aromatic polyamide is a semi-aromatic polyamide, optionally modified with urea units, in particular a PA MXD6 and a PA MXD10 or a semi-aromatic polyamide of formula A / XT in which A is chosen from a unit obtained from at least one amino acid, a unit obtained from at least one lactam and at least one unit corresponding to the formula (Ca diamine).(Cb diacid), with a representing the number of carbon atoms of the diamine and b representing the number of carbon atoms of the diacid, a and b each being between 4 and 36, advantageously between 9 and 18, the unit (Ca diamine) being chosen from aliphatic, linear or branched diamines, cycloaliphatic diamines and alkylaromatic diamines and the unit (Cb diacid) being chosen from aliphatic, linear or branched diacids, cycloaliphatic diacids and aromatic diacids; X.T denotes a unit obtained from the polycondensation of a Cx diamine and terephthalic acid, with x representing the number of carbon atoms of the Cx diamine, x being between 6 and 36, advantageously between 9 and 18, in particular a polyamide of formula A / 6T, A / 9T, A / 10T or A / 11T, A being as defined above, in particular a polyamide PA 6 / 6T, a PA 66 / 6T, a PA 6I / 6T, a PA MPMDT / 6T, a PA PA11 / 10T, a PA 11 / 6T / 10T, a PA MXDT / 10T, a PA MPMDT / 10T, a PA BACT / 10T, a PA BACT / 6T, a PA 11 / BACT, PA BACT / 10T / 6T, PA 11 / BACT / 10T, T corresponds to the acid terephthalic acid, MXD stands for m-xylylene diamine, MPMD stands for methylpentamethylene diamine, and BAC stands for 1,3-bis(aminomethyl)cyclohexane.

[0021] Preferably, said at least one reactive thermoplastic polymer is chosen from:

[0022] - an aliphatic polyamide chosen from polyamide 11 (PA-11), polyamide 12 (PA-12), polyamide 66 (PA-66), polyamide 46 (PA-46), polyamide 610 (PA-610), polyamide 612 (PA-612), polyamide 1010 (PA-1010), polyamide 1012 (PA-1012), polyamide 11 / 1010 and polyamide 12 / 1010, or a mixture thereof or a copolyamide thereof, and polyetheramide or polyetheresteramide copolymers (PEBA) (or copolymer with polyamide blocks and polyether blocks), or - a semi-aromatic polyamide, optionally modified with urea units, in particular a PA MXD6 and a PA MXD10 or a semi-aromatic polyamide of formula A / XT in which A is chosen from a unit obtained from at least one amino acid, a unit obtained from at least one lactam and at least one unit corresponding to the formula (Ca diamine).(Cb diacid), with a representing the number of carbon atoms of the diamine and b representing the number of carbon atoms of the diacid, a and b each being between 4 and 36, advantageously between 9 and 18, the unit (Ca diamine) being chosen from aliphatic, linear or branched diamines, cycloaliphatic diamines and alkylaromatic diamines and the unit (Cb diacid) being chosen from aliphatic, linear or branched diacids, cycloaliphatic diacids and aromatic diacids; X.T denotes a unit obtained from the polycondensation of a Cx diamine and terephthalic acid, with x representing the number of carbon atoms of the Cx diamine, x being between 6 and 36, advantageously between 9 and 18, in particular a polyamide of formula A / 6T, A / 9T, A / 10T or A / 11T, A being as defined above, in particular a polyamide PA 6 / 6T, a PA 66 / 6T, a PA 6I / 6T, a PA MPMDT / 6T, a PA PA11 / 10T, a PA 11 / 6T / 10T, a PA MXDT / 10T, a PA MPMDT / 10T, a PA BACT / 10T, a PA BACT / 6T, a PA 11 / BACT, PA BACT / 10T / 6T, PA 11 / BACT / 10T, T corresponds to the acid terephthalic acid, MXD stands for m-xylylene diamine, MPMD stands for methylpentamethylene diamine, and BAC stands for 1,3-bis(aminomethyl)cyclohexane.

[0023] Preferably, the reactive thermoplastic polymer is a semi-aromatic polyamide chosen from a PA MPMDT / 6T, a PA PA11 / 10T, a PA 11 / BACT, a PA 11 / 6T / 10T, a PA MXDT / 10T, a PA MPMDT / 10T, a PA BACT / 10T, a PA BACT / 6T, PA BACT / 10T / 6T, a PA 11 / BACT / 6T, PA 11 / MPMDT / 10T, PA 11 / BACT / 10T, PA 11 / MXDT / 10T.

[0024] Preferably, the reactive thermoplastic polymer is PA11 or PA12, preferably PA11.

[0025] Preferably, the overmolding resin composition is the same as or different from the matrix resin, preferably it comprises an aliphatic or semi-aromatic polyamide polymer as defined above. Preferably, the fibrous material comprises continuous fibers selected from:

[0026] - fibers of mineral origin such as carbon, glass, silicon carbide, basalt, silica fibers;

[0027] - fibres of plant origin, in particular fibres based on flax, hemp, lignin, bamboo, silk, in particular spider silk or sisal, cellulosic fibres, in particular viscose;

[0028] - fibers of organic origin such as amorphous thermoplastic fibers with a glass transition temperature Tg greater than the Tg of the polymer of the matrix resin composition when the latter is amorphous or greater than the Tf of the polymer of the matrix resin composition when the latter is semi-crystalline and whose Tg (in the case of an amorphous material) or Tf (in the case of a semi-crystalline material) is greater than the injection temperature of the overmolding resin composition, or semi-crystalline thermoplastic fibers with a melting temperature Tf greater than the Tg of the polymer of the matrix resin composition when the latter is amorphous or greater than the Tf of the polymer of the matrix resin composition and whose Tg (in the case of an amorphous material) or Tf (in the case of a semi-crystalline material) is greater than the injection temperature of the overmolding resin composition, or a mixture of two or of several of said fibers,preferably a mixture of carbon, glass or silicon carbide fibers, in particular carbon fibers, or mixtures thereof.,

[0029] Preferably, the overmolded composite structure does not include an adhesion primer between components C1 and C2.

[0030] Preferably, the matrix resin composition does not comprise a filler or comprises less than 2% by weight of filler, preferably from 0.01 to 0.5% by weight of filler relative to the weight of the matrix resin composition.

[0031] Preferably, the reactive thermoplastic polymer has a melt viscosity measured by capillary rheology at a shear rate of 1800 s-1 of between 0.05 and 1000 Pa.s, preferably between 0.1 and 1000 Pa.s, preferably between 0.3 and 1000 Pa.s, preferably between 0.3 and 500 Pa.s, more preferably between 0.3 and 250 Pa.s, for example between 0.3 and 100 Pa.s, even more preferably between 0.3 and 50 Pa.s, more preferably between 0.3 and 25 Pa.s, even more preferably between 0.3 and 10 Pa.s, preferably between 0.3 and 5 Pa.s. Preferably, the reactive thermoplastic polymer is an amorphous polyamide or a semi-crystalline polyamide having an absolute enthalpy of fusion in component (C1) before overmolding of less than 12 J / g of matrix resin, preferably less than 8 J / g of matrix resin, preferably less than 5 J / g of matrix resin, calculated according to equation (1)

[0032] Equation (1): the enthalpy measurement being carried out by differential scanning calorimetry (DSC) according to the ISO 11357-3 standard of 2013, the melting and crystallization peaks being the first heating peaks at a rate of 20 K / min.

[0033] Preferably:

[0034] - the matrix resin comprises an aliphatic polyamide, preferably PA11 or PA12, preferably PA11, and the overmolding resin a PEBA; or

[0035] - the matrix resin comprises an aliphatic polyamide, preferably PA11 or PA12, preferably PA11, and the overmolding resin an aliphatic polyamide, preferably PA11 or PA12, preferably PA11; or

[0036] - the matrix resin comprises an aliphatic polyamide, preferably PA11 or PA12, preferably PA11, and the overmolding resin a semi-aromatic polyamide; or

[0037] - the matrix resin comprises a semi-aromatic polyamide and the overmolding resin an aliphatic polyamide, preferably PA11 or PA12, preferably PA11.

[0038] The present invention also relates to a method of manufacturing an overmolded composite structure according to the invention, comprising a step of overmolding the component C2 on at least part of the surface S of the component C1.

[0039] Preferably, the overmolding step is an injection overmolding step.

[0040] The present application also relates to the use of the overmolded composite structures according to the invention for the manufacture of parts, particularly in the fields of mechanics, aeronautics, nautical, automotive, oil and gas (in particular offshore, gas storage), energy, health and medicine, sports and leisure and electronics.

[0041] The present application also relates to the use of a matrix resin composition according to the invention for the preparation of an overmolded composite structure comprising a first component (C1) comprising at least one fibrous material and said matrix resin composition; and a second component (C2) comprising an overmolding resin composition, to obtain a peel force measured according to a protocol adapted from the ISO 4578:1997 standard (90° peel) greater than or equal to 50 N / cm, preferably greater than or equal to 70 N / cm and particularly preferred greater than or equal to 100 N / cm between the component (C1) and the component (C2).

[0042] Description of figures

[0043] Figure 1 is a DSC thermogram of a component C1 according to the invention obtained with a matrix resin comprising a semi-aromatic polyamide. This graph corresponds to the 1 ère heating of the DSC analysis program and shows the area (A) under the peak of 1ère heating corresponding to the crystallization peak of 1 ère heating and the area (B) under the peak of 1 ère heating corresponding to the melting peak of 1 ère heating. The enthalpy measurement is carried out by differential scanning calorimetry (DSC) according to ISO 11357-3 of 2013, the melting and crystallization peaks being the first heating peaks at a rate of 20 K / min.

[0044] Figure 2 is a representative schematic of the test specimens prepared in Example 2.

[0045] Detailed description

[0046] The invention is now described in more detail and in a non-limiting manner in the following description.

[0047] Unless otherwise stated, all percentages are by mass.

[0048] In this text, the quantities indicated for a given species may apply to this species according to all its definitions (as mentioned in this text), including the more restricted definitions.

[0049] In the present description, the term "fibrous material" means a set of unitary reinforcing fibers. The term "thermoplastic," or thermoplastic polymer, means a material that is generally solid at room temperature, which may be semi-crystalline or amorphous, and which softens upon an increase in temperature, in particular after passing its glass transition temperature (Tg) and flows at a higher temperature when it is amorphous, or which may exhibit a frank melting upon passing its so-called melting temperature (Tf) when it is semi-crystalline, and which becomes solid again upon a decrease in temperature below its crystallization temperature (for a semi-crystalline material) and below its glass transition temperature (for an amorphous material).

[0050] Tg and Tf are determined by differential scanning calorimetry (DSC) according to standard 11357-2:2013 and 11357-3:2013 respectively.

[0051] Overmolded composite structure

[0052] The invention relates firstly to an overmolded composite structure comprising: i) a first component (C1) comprising at least one fibrous material and a matrix resin composition, said matrix resin composition comprising at least one reactive thermoplastic polymer, and optionally a chain extender and / or chain limiter and / or catalyst and / or one or more additives, said thermoplastic polymer has a number-average molecular weight Mn of between 3000 and 35000 g / mol, preferably between 5000 and 20000 g / mol, preferably between 5000 and 15000 g / mol, preferentially between 5000 and 10000 g / mol; and ii) a second component (C2) comprising an overmolding resin composition, said first component (C1) comprising at least one surface (S) and said component (C2) adhering to said component (C1) on at least a portion of said surface (S).

[0053] It should be understood that the first component (C1) may be of any shape, 2D or 3D, and in particular may be in the form of a parallelepiped, or a more complex 2D or 3D shape and may therefore comprise several surfaces (S). The component (C2) adheres to said component (C1) on at least one of its surfaces (S). The invention also covers the case where the component (C2) adheres to said component (C1) on several distinct surfaces (S), said component (C2) being able to be identical or different depending on the surfaces (S). In a particularly advantageous manner, the inventors have shown that the specific choice of the matrix resin composition makes it possible to obtain good cohesion between the components (C1) and (C2) and in particular good adhesion (or "cohesion" in English) without requiring the use of an adhesion primer between the components (C1) and (C2).Particularly advantageously, the inventors have shown that the specific choice of the matrix resin composition makes it possible to obtain good adhesion between the components (C1) and (C2), characterized by a peel force, measured according to a protocol adapted from the ISO 4578:1997 standard (90° peel) greater than or equal to 50N / cm, preferably greater than or equal to 70 N / cm and particularly preferred greater than or equal to 100 N / cm.

[0054] Overmolding consists of performing a molding on a product (here the component (C1)). It must be understood that an overmolded composite structure is different from a combination of two impregnated fibrous materials. The overmolding resin composition, unlike impregnated fibrous materials, cannot include continuous fibers. Indeed, the presence of continuous fibers would make it unusable in overmolding processes, for example in injection overmolding processes.

[0055] Overmolding consists of molding, in a mold containing the prefabricated component (C1), the second component (C2) which is introduced at a temperature higher than the glass transition temperature of the composition (C2) if said composition (C2) comprises an amorphous polymer or higher than the melting temperature of the composition (C2) if said composition (C2) comprises a semi-crystalline polymer.

[0056] Matrix resin composition

[0057] The term "reactive thermoplastic polymer" means that said thermoplastic polymer is capable of reacting with the overmolding resin or optionally with itself by condensation with release of water or by substitution or by reaction with a chain extender by polyaddition or polycondensation. Particularly advantageously, said polymer can react with the overmolding resin via its terminal functionalities, or by exchange reaction between their respective repeating units, or by reaction between their repeating units and their terminal functionalities. Optionally, this reaction is made possible by the addition of additives. When this "reactive thermoplastic polymer" reacts with itself, it has an initial number-average molecular weight M and an initial melt viscosity rp.When its temperature is higher than its glass transition temperature, in particular higher than its melting temperature, this mass evolves by reaction with itself, which means that the number-average molecular mass Mm and the melt viscosity r|2 of the polymer resulting from the reaction of the reactive thermoplastic polymer with itself are greater than or equal to the initial molecular mass M and the initial melt viscosity rp. Preferably, Mm is greater than Mm by at least 5%, preferably by at least 10%.

[0058] In the following, we will designate by molecular mass in number of the reactive thermoplastic polymer the molecular mass in number of the thermoplastic polymer if it has not reacted with itself or that of the polymer resulting from its reaction with itself (Mm). By analogy, in the following, we will designate by viscosity in the molten state the viscosity of the thermoplastic polymer if it has not reacted with itself or that of the polymer resulting from its reaction with itself (q 2)

[0059] The chain extenders can be any type of chain extender known to those skilled in the art, such as those cited in patent application FR1907685.

[0060] These number-average molecular masses are obviously understood to be in the solid state after cooling of the polymer.

[0061] Preferably, the reactive thermoplastic polymer is a polyamide, polycarbonate or polymethacrylate, preferably polyamide. Optionally, it comprises epoxy-type functional groups.

[0062] Preferably, the reactive polymer is a polyamide, especially an aliphatic, cycloaliphatic or semi-aromatic polyamide.

[0063] Advantageously, the reactive thermoplastic polymer is a homopolyamide or a copolyamide or a mixture thereof.

[0064] The number-average molecular mass Mn of said reactive thermoplastic polymer is between 3000 and 35000 g / mol, preferably between 5000 and 20000 g / mol, preferably between 5000 and 15000 g / mol, preferentially between 5000 and 10000 g / mol. This number-average molecular mass can be determined in particular by measurement by size exclusion chromatography according to ISO 16014-1:2012, 16014-2:2012 and 16014-3 using the following conditions:

[0065] - Device: Waters Alliance 2695 instrument

[0066] - Solvent: hexafluoroisopropanol stabilized with 0.05M potassium trifluoroacetate

[0067] - Flow rate: 1 ml / minute

[0068] - Column temperature: 40°C.

[0069] - Two columns in series: 1000 Â PFG and 100 Â PFG (PPS)

[0070] - Sample concentration: 1 g / L (dissolution at room temperature for 24 h)

[0071] - Filtration of samples using a syringe fitted with an ACRODISC PTFE filter, diameter 25mm, porosity 0.2 pm

[0072] - Injection volume: 100pl

[0073] - Refractometric detection at 40°C with LIV detection at 228 nm

[0074] - Calibration by PMMA standards from 1,900,000 to 402 g.mol-1. Calibration curve modeled by a fifth-degree polynomial.

[0075] Advantageously, the composite obtained with such a matrix makes it possible to obtain even more improved adhesion with the overmolding matrix and in particular even greater peel strength.

[0076] Preferably, said at least one reactive thermoplastic polymer has a viscosity in the molten state measured by capillary rheology at a shear of 1800 s' 1between 0.05 and 1000 Pa.s, preferably between 0.1 and 1000 Pa.s, preferably between 0.3 and 1000 Pa.s, preferably between 0.3 and 500 Pa.s, more preferably between 0.3 and 250 Pa.s, for example between 0.3 and 100 Pa.s, even more preferably between 0.3 and 50 Pa.s, more preferably between 0.3 and 25 Pa.s, even more preferably between 0.3 and 10 Pa.s, preferably between 0.3 and 5 Pa.s. The melt viscosity is measured by capillary rheology using a Gottfert Rheotester 2000 device. The measurement temperature (T) follows the following inequality Tf < T < Tf+70°C. The measurement is carried out according to the ISO11443:2014 standard. The preheating time is 240 seconds, the die has a diameter of 1 mm and a length of 30 mm. The shear and viscosity are corrected by Rabinowitsch. Preferably, the melt viscosity is preferably measured at Tf+50°C, Tf being the melting temperature of at least one polyamide.Advantageously, the composite obtained with such a matrix makes it possible to obtain even more improved adhesion with the overmolding matrix and in particular even greater peel strength.

[0077] The reactive thermoplastic polymer constituting the matrix resin of the fibrous material may consist of a mixture of thermoplastic polymers, at least one of which is reactive. This polymer or mixture of polymers may be ground into powder form, so that it can be used in a device such as a tank, in particular in a fluidized bed or in aqueous or solvent dispersion.

[0078] The device in the form of a tank, particularly in a fluidized bed, can be open or closed.

[0079] Optionally, the matrix resin further comprises carbonaceous fillers, in particular carbon black or carbonaceous nanofillers, preferably selected from carbonaceous nanofillers, in particular graphenes and / or carbon nanotubes and / or carbon nanofibrils or mixtures thereof. These fillers make it possible to conduct electricity and heat, and therefore make it possible to facilitate the melting of the matrix when it is heated.

[0080] Optionally, said reactive thermoplastic polymer comprises at least one additive, in particular chosen from a catalyst, an antioxidant, a thermal stabilizer, a UV stabilizer, a light stabilizer, a lubricant, a filler, a plasticizer, a flame retardant, a nucleating agent, a colorant, an electrically conductive agent, a thermally conductive agent or a mixture thereof.

[0081] Advantageously, said additive is chosen from a flame retardant agent, an electrically conductive agent and a thermally conductive agent.

[0082] Said flame retardants may be halogen-free flame retardants, as described in US 2008 / 0274355 and in particular a metal salt chosen from a metal salt of phosphinic acid, a metal salt of diphosphinic acid, a polymer containing at least one metal salt of phosphinic acid, a polymer containing at least one metal salt of diphosphinic acid or red phosphorus, an antimony oxide, a zinc oxide, an iron oxide, a magnesium oxide or metal borates such as a zinc borate or melamine pyrophosphates and melamine cyanurates. They may also be halogenated flame retardants such as a brominated or polybrominated polystyrene, a brominated polycarbonate or a brominated phenol.

[0083] Advantageously, said reactive thermoplastic polymer is a polyamide and is chosen from aliphatic polyamides, cycloaliphatic polyamides and semi-aromatic polyamides (polyphthalamides).

[0084] Preferably,

[0085] - said aliphatic polyamide is chosen from polyamide 6 (PA-6), polyamide 11 (PA-11), polyamide 12 (PA-12), polyamide 66 (PA-66), polyamide 46 (PA-46), polyamide 610 (PA-610), polyamide 612 (PA-612), polyamide 1010 (PA-1010), polyamide 1012 (PA-1012), polyamide 11 / 1010 and polyamide 12 / 1010, or a mixture thereof or a copolyamide thereof, and polyetheramide or polyetheresteramide (PEBA) copolymers (or copolymer with polyamide blocks and polyether blocks), preferably chosen from polyamide 6 (PA-6), polyamide 11 (PA-11), polyamide 12 (PA-12), polyamide 66 (PA-66), polyamide 46 (PA-46), polyamide 610 (PA-610), polyamide 612 (PA-612), polyamide 1010 (PA-1010), polyamide 1012 (PA-1012), polyamide 11 / 1010 and polyamide 12 / 1010, or a mixture thereof, and

[0086] - said semi-aromatic polyamide is a semi-aromatic polyamide, optionally modified by urea units, in particular a PA MXD6 and a PA MXD10 or a semi-aromatic polyamide of formula X / YAr, as described in EP1505099, in particular a semi-aromatic polyamide of formula A / XT in which A is chosen from a unit obtained from at least one amino acid, a unit obtained from at least one lactam and at least one unit corresponding to the formula (Ca diamine).(Cb diacid), with a representing the number of carbon atoms of the diamine and b representing the number of carbon atoms of the diacid, a and b each being between 4 and 36, advantageously between 9 and 18, the unit (Ca diamine) being chosen from aliphatic, linear or branched diamines, cycloaliphatic diamines and alkylaromatic diamines and the unit (Cb diacid) being chosen from aliphatic, linear or branched diacids, cycloaliphatic diacids and aromatic diacids;.

[0087] XT denotes a unit obtained from the polycondensation of a Cx diamine and terephthalic acid, with x representing the number of carbon atoms of the Cx diamine, x being between 6 and 36, advantageously between 9 and 18, in particular a polyamide of formula A / 6T, A / 9T, A / 10T or A / 11T, A being as defined above, in particular a polyamide PA 6 / 6T, a PA 66 / 6T, a PA 6I / 6T, a PA MPMDT / 6T, a PA PA11 / 10T, a PA 11 / 6T / 10T, a PA MXDT / 10T, a PA MPMDT / 10T, a PA BACT / 10T, a PA BACT / 6T, a PA 11 / BACT, PA BACT / 10T / 6T, a PA 11 / BACT / 10T.

[0088] T stands for terephthalic acid, MXD stands for m-xylylenediamine, MPMD stands for methylpentamethylenediamine, and BAC stands for 1,3-bis(aminomethyl)cyclohexane.

[0089] Preferably:

[0090] - said aliphatic polyamide is chosen from polyamide 11 (PA-11), polyamide 12 (PA-12), polyamide 66 (PA-66), polyamide 46 (PA-46), polyamide 610 (PA-610), polyamide 612 (PA-612), polyamide 1010 (PA-1010), polyamide 1012 (PA-1012), polyamide 11 / 1010 and polyamide 12 / 1010, or a mixture thereof or a copolyamide thereof, and polyetheramide or polyetheresteramide (PEBA) copolymers (or copolymer with polyamide blocks and polyether blocks), preferably chosen from polyamide 11 (PA-11), polyamide 12 (PA-12), polyamide 66 (PA-66), polyamide 46 (PA-46), polyamide 610 (PA-610), polyamide 612 (PA-612), polyamide 1010 (PA-1010), polyamide 1012 (PA-1012), polyamide 11 / 1010 and polyamide 12 / 1010, or a mixture thereof, and

[0091] - said semi-aromatic polyamide is a semi-aromatic polyamide, optionally modified by urea units, in particular a PA MXD6 and a PA MXD10 or a semi-aromatic polyamide of formula X / YAr, as described in EP1505099, in particular a semi-aromatic polyamide of formula A / XT in which A is chosen from a unit obtained from at least one amino acid, a unit obtained from at least one lactam and at least one unit corresponding to the formula (Ca diamine).(Cb diacid), with a representing the number of carbon atoms of the diamine and b representing the number of carbon atoms of the diacid, a and b each being between 4 and 36, advantageously between 9 and 18, the unit (Ca diamine) being chosen from aliphatic, linear or branched diamines, cycloaliphatic diamines and alkylaromatic diamines and the unit (Cb diacid) being chosen from aliphatic, linear or branched diacids, cycloaliphatic diacids and aromatic diacids;.

[0092] XT denotes a unit obtained from the polycondensation of a Cx diamine and terephthalic acid, with x representing the number of carbon atoms of the Cx diamine, x being between 6 and 36, advantageously between 9 and 18, in particular a polyamide of formula A / 6T, A / 9T, A / 10T or A / 11T, A being as defined above, in particular a polyamide PA 6 / 6T, a PA 66 / 6T, a PA 6I / 6T, a PA MPMDT / 6T, a PA PA11 / 10T, a PA 11 / 6T / 10T, a PA MXDT / 10T, a PA MPMDT / 10T, a PA BACT / 10T, a PA BACT / 6T, a PA 11 / BACT, PA BACT / 10T / 6T, a PA 11 / BACT / 10T.

[0093] T stands for terephthalic acid, MXD stands for m-xylylenediamine, MPMD stands for methylpentamethylenediamine, and BAC stands for 1,3-bis(aminomethyl)cyclohexane.

[0094] Preferably, ledit polyamide is a semi-aromatic polyamide chosen from a MPMDT / 6T PA, a PA11 / 10T PA, an 11 / BACT PA, an 11 / 6T / 10T PA, an MXDT / 10T PA, an MPMDT / 10T PA, and a PABA10 / PAT / PAT BACT / 10T / 6T, and PA 11 / BACT / 6T, PA 11 / MPMDT / 10T, PA 11 / BACT / 10T, and PA 11 / MXDT / 10T.

[0095] Preferably, the read polyamide is an aliphatic PA11 or PA12 polyamide, preferably PA11 .

[0096] According to one variant, the polyamide is a polyetheramide or polyetheresteramide (PEBA) copolymer (or polyamide block and polyether block copolymer). The polyamide blocks of these copolymers can be chosen from polyamide 6, polyamide 11, polyamide 6.10, polyamide 6.12, polyamide 10.10, polyamide 10.12, polyamide 10.14, polyamide 12 blocks, and combinations thereof. The polyether blocks of these copolymers can be chosen from PEG (polyethylene glycol), PPG (polypropylene glycol), PO3G (polytrimethylene glycol), PTMG (polytetramethylene glycol or polytetrahydrofuran) blocks, and combinations thereof. Such copolymers can be prepared according to one of the patent applications FR2846332 in the name of ATOFINA or EP1482011 in the name of UBE INDUSTRIE

[0097] Preferably, the reactive thermoplastic polymer is an amorphous polyamide or a semi-crystalline polyamide having an absolute enthalpy of fusion in component (C1) before overmolding of less than 12 J / g of matrix resin, preferably less than 8 J / g of matrix resin, preferably less than 5 J / g of matrix resin, calculated according to equation (1)

[0098] Equation (1): the enthalpy measurement being carried out by differential scanning calorimetry (DSC) according to the ISO 11357-3 standard of 2013, the melting and crystallization peaks being the first heating peaks at a speed of 20 K / min. Advantageously, the composite obtained with such a matrix makes it possible to obtain an even more improved adhesion with the overmolding matrix and in particular an even greater peel force. It must therefore be understood that the component (C1) is preferably obtained by the use of a matrix resin composition in which the at least one polyamide is an amorphous or a semi-crystalline polyamide an absolute value of fusion enthalpy in the component (C1) before overmolding of less than 12 J / g of matrix resin, preferably less than 8 J / g, preferably less than 5 J / g.

[0099] The following information helps to understand how the measurement of the enthalpy of fusion is carried out from the component (C1). It should be understood that during the DSC analysis of the component (C1), and in particular during the first heating, crystals initially not present in the component (C1) may be formed during the first heating cycle and the formation of these crystals not initially present in the component (C1) will increase the enthalpy of fusion measured in this same first heating. In order to determine the actual enthalpy of fusion of the component (C1), it is therefore necessary to subtract from the area of ​​the peak of the enthalpy of fusion of 1 ère heating (peak B in figure 1) the area of ​​the crystallization enthalpy peak of 1 èreheating (peak A in figure 1) if it is present. It is also agreed that this real fusion enthalpy of the component (C1) is noted in absolute value. It is also agreed that the crystallization enthalpy of the first heating can be zero if this is zero then the real fusion enthalpy of the component (C1) is equal to the fusion enthalpy of 1 ère heated.

[0100] The actual fusion enthalpy thus measured and calculated is then corrected with respect to the mass rate of matrix resin (and any fusible charges of the matrix resin) in component (01) and related to the mass of matrix resin in component (01), the enthalpies mentioned above are therefore in J / g of matrix resin.

[0101] The mass content of matrix resin can be obtained according to ASTM D3171-22 by acid digestion of the resin and weighing before / after digestion. Fibrous material

[0102] Preferably, the fibrous material consists of fibers, in particular fibers of mineral, organic or vegetable origin, generally in the form of strands.

[0103] The fibers are preferably continuous fibers.

[0104] Among the fibers of mineral origin, we can cite carbon fibers, glass fibers, basalt fibers, silica fibers, or silicon carbide fibers for example.

[0105] Advantageously, these are carbon fibers whose number of fibers per strand is greater than or equal to 12K (therefore 12,000 filaments / strand), in particular greater than or equal to 24K (24,000 filaments per strand) or glass fibers whose grammage is greater than or equal to 1200 Tex, in particular greater than or equal to 2400 Tex, in particular greater than or equal to 2400 Tex.

[0106] Among the fibers of plant origin, we can cite in particular fibers based on flax, hemp, lignin, bamboo, silk, in particular spider silk or sisal, cellulosic fibers, in particular viscose. These fibers of plant origin can be used pure, treated or coated with a coating layer, in order to facilitate the adhesion and impregnation of the matrix resin composition.

[0107] Among the fibers of organic origin, mention may be made of fibers of organic origin such as amorphous thermoplastic fibers with a glass transition temperature Tg greater than the Tg of the polymer of the matrix resin composition when the latter is amorphous or greater than the Tf of the polymer of the matrix resin composition when the latter is semi-crystalline and whose Tg (in the case of an amorphous material) or Tf (in the case of a semi-crystalline material) is greater than the injection temperature of the overmolding resin composition, or semi-crystalline thermoplastic fibers with a melting temperature Tf greater than the Tg of the polymer of the matrix resin composition when the latter is amorphous or greater than the Tf of the polymer of the matrix resin composition and whose Tg (in the case of an amorphous material) or Tf (in the case of a semi-crystalline material) is greater than the injection temperature of the overmolding resin composition. overmolding,or a mixture of two or more of said fibers, preferably a mixture of carbon, glass or silicon carbide fibers, in particular carbon fibers.,

[0108] Preferably, the fibers are mineral fibers, especially a mixture of carbon, glass or silicon carbide fibers, especially carbon fibers.

[0109] The fibrous material can also be a fabric, braided or woven with fibers. It can also correspond to fibers with holding threads.

[0110] These constituent fibers can be used alone or in blends. Thus, organic fibers can be blended with mineral fibers to be impregnated with thermoplastic polymer, optionally with a chain extender, and form the impregnated fibrous material.

[0111] Organic fiber strands can have several weights. They can also have several geometries. The fibers can be in the form of short fibers, which then make up felts or nonwovens which can be in the form of strips, sheets, or pieces, or in the form of continuous fibers, which make up 2D fabrics, braids or strands of unidirectional (UD) fibers or nonwovens. The fibers constituting the fibrous material can also be in the form of a mixture of these reinforcing fibers of different geometries. Preferably, the fibers are continuous.

[0112] Preferably the fibrous material consists of continuous carbon, glass or silicon carbide fibers or their mixture, in particular carbon fibers. It is used in the form of a strand or several strands.

[0113] In one embodiment, the matrix resin composition is distributed as homogeneously as possible within the fibers in order to obtain a minimum of porosities, that is to say a minimum of voids between the fibers. Indeed, the presence of porosities in this type of material can act as stress concentration points, during mechanical tensile stress for example, and which then form rupture initiation points of the impregnated fibrous material and weaken it mechanically. A homogeneous distribution of the matrix resin composition therefore improves the mechanical strength and homogeneity of the composite material (component (C1)) formed from these impregnated fibrous materials.

[0114] The fiber content in component (C1) is preferably between 40 and 65% by volume, preferably between 40 and 60% by volume, in particular between 50 and 60% by volume.

[0115] The measurement of the impregnation rate can be carried out by image analysis (using a microscope or a camera or digital camera, in particular), of a cross-section of the component (C1), by dividing the surface of the component (C1) impregnated with the matrix resin composition by the total surface of the product (impregnated surface including the matrix resin and the fibers plus the surface of the porosity). In order to obtain a good quality image, it is preferable to coat the component (C1) cut in its transverse direction in a standard cold-polymerizing polishing resin and to polish with a standard protocol allowing observation of the sample under a microscope at a magnification of at least 6 times. Advantageously, the porosity rate of said impregnated fibrous material (component (C1)) is less than 10%, in particular less than 5%, in particular less than 2%.

[0116] It should be noted that a zero porosity rate is difficult to achieve (or measure) and that consequently, advantageously the porosity rate is greater than 0% but lower than the rates cited above.

[0117] The porosity rate corresponds to the closed porosity rate and can be determined either by electron microscopy or as the relative difference between the theoretical density and the experimental density of said impregnated fibrous material as described in the examples section of the present invention.

[0118] The component (C1) can be obtained by any method known to those skilled in the art from the fibrous material and in particular for example by coating on a fluidized bed, impregnation in aqueous or solvent dispersion of polymer powder, extrusion at the head of a square of molten polymer (or molten route), dusting of dry powder excluding exclusive voluntary electrostatic dusting.

[0119] Particularly preferably, the component (C1) of the invention can be obtained according to the method described in WO2018 / 234436 and particularly preferably the fluidized method described on pages 15 to 21 of WO2018 / 234436.

[0120] Overmolding resin composition

[0121] The overmolding resin composition according to the present invention comprises at least one polymer chosen from the polymers used in the matrix resin.

[0122] Preferably, the polymer of the overmolding resin is the same as or different from the polymer of the matrix resin. Preferably, the polymer of the overmolding resin composition and that of the matrix resin composition are of the same chemical nature (in particular functional group) and have the same physical properties.

[0123] Preferably, the overmolding resin composition according to the present invention comprises at least one polymer chosen from polyamides, or polyetheramide or polyetheresteramide copolymers.

[0124] The polyamides are preferably as defined above for the matrix resin.

[0125] When the overmolding resin composition comprises at least one polyamide, this may be identical to or different from that of the matrix resin composition. Preferably, the polymer of the overmolding resin composition and that of the matrix resin composition are of the same chemical nature (in particular functional group) and have the same physical properties.

[0126] Preferably, the polymer of the overmolding resin composition and that of the matrix resin composition are identical.

[0127] Particularly preferably:

[0128] - the matrix resin comprises an aliphatic polyamide, preferably PA11 or PA12, for example PA11, and the overmolding resin a PEBA; or

[0129] - the matrix resin comprises an aliphatic polyamide, preferably PA11 or PA12, for example PA11, and the overmolding resin an aliphatic polyamide, preferably PA11 or PA12, preferably PA11; or

[0130] - the matrix resin comprises an aliphatic polyamide, preferably PA11 or PA12, for example PA11, and the overmolding resin a semi-aromatic polyamide; or

[0131] - the matrix resin comprises a semi-aromatic polyamide and the overmolding resin an aliphatic polyamide, preferably PA11 or PA12, for example PA11.

[0132] Optionally, the overmolding resin composition comprises at least one additive, in particular chosen from a catalyst, an antioxidant, a thermal stabilizer, a LIV stabilizer, a light stabilizer, a lubricant, a release agent, a filler, a plasticizer, a flame retardant, a nucleating agent, a chain extender and a colorant, an electrically conductive agent, a thermally conductive agent or a mixture thereof.

[0133] Advantageously, said additive is chosen from a thermal stabilizer, an antioxidant, a flame retardant, an electrically conductive agent and a thermally conductive agent.

[0134] The surface resin composition may further comprise liquid crystal polymers or cyclized poly(butylene terephthalate), or mixtures thereof. These compounds notably make it possible to fluidize the matrix resin in the molten state, for better penetration into the core of the fibrous material.

[0135] The fillers may for example be chosen from carbonaceous fillers, in particular carbon black or carbonaceous nanofillers, preferably chosen from graphenes, carbon nanotubes, carbon nanofibrils or mixtures thereof. Particularly preferably, the overmolding resin composition of the invention comprises from 0.01% to 2% by weight of filler, preferably from 0.01% to 0.5% by weight of filler relative to the total weight of the overmolding resin composition. The overmolding resin composition may also comprise fibers, and more preferably short fibers, preferably short glass fibers or short carbon fibers.

[0136] The fibers preferably have a length of between 2 and 13 mm, preferably 3 to 8 mm before use of the compositions.

[0137] Component (C2) may be in the form of a foam, thus making it lighter. The term "foam" or "polymer foam" refers to a two-phase material containing a continuous phase consisting of the polymer matrix and a continuous or discontinuous gas phase. A foam is said to have closed porosity when the polymer matrix is ​​the only continuous phase in the system. The gas is present only in the form of discrete gas bubbles. Otherwise, in an open porosity foam, the gas phase and the polymer phase are continuous. The foam according to the invention may be prepared by mixing the overmolding resin with a blowing agent (and optionally one or more additives), then carrying out a foaming step. The blowing agent may be a chemical or physical agent, or may also consist of any type of hollow object or any type of expandable microsphere.By way of example, but not limited to, the physical blowing agent may be nitrogen or carbon dioxide, or a hydrocarbon, chlorofluorocarbon, hydrochlorocarbon, hydrofluorocarbon or hydrochlorofluorocarbon (saturated or unsaturated) or a mixture thereof. The physical blowing agent may be in gaseous, liquid or supercritical form and in this case be converted into gaseous phase during the foaming step. This same foaming step may be caused by a thermodynamic instability such as a pressure and / or temperature jump. For polyamides in particular, said foam has a density less than or equal to 1000 kg / m3, preferably less than or equal to 800 kg / m3, preferably less than or equal to 600 kg / m3, preferably less than or equal to 500 kg / m3, preferably less than or equal to 400 kg / m3, more particularly preferably less than or equal to 300 kg / m3, ideally less than or equal to 200 kg / m3.Foam density control can be achieved using techniques known to those skilled in the art, particularly by adapting the parameters of the preparation process. The density, or density, is measured according to ISO 1183-1 using the vertical thrust method in water (23°C).

[0138] Preferably, the thickness of the component (C1) is between 0.07 and 50 mm, preferably between 0.15 and 50 mm, even more preferably between 0.15 and 10 mm, for example between 0.15 and 4 mm and the thickness of the component (C2) is between 0.5 and 50 mm, preferably between 0.5 and 10 mm, preferably between 0.5 and 5 mm, preferably between 0.15 and 2 mm.

[0139] Particularly advantageously, the overmolded composite structure of the present invention does not comprise an adhesion primer between the components (C1) and (C2). Thus, and particularly advantageously, the component (C1) and the component (C2) in the composite overmolded structure are in direct contact without any intermediate layer. The cohesion between the components (C1) and (C2) is provided by the specific choice of the polyamide of the matrix resin composition defined above.

[0140] The absence of an adhesion primer allows easier recycling of the overmolded composite structure. Recycling may be carried out in particular by grinding the overmolded composite structure to obtain a ground material, heating the ground material until it melts to form a molten mass; and extruding the molten mass in the form of granules. Recycling may also be carried out by disassembling the two components (C1) and (C2), for example by heating or cooling, then recycling or reusing components (C1) and (C2) separately.

[0141] The expression "adhesion primer" means a compound which, when applied to a support, in this case component (C1), and intended to receive a second support, in this case component (C2), makes it possible to strengthen the bond between the two supports and therefore the creation of a chemical and / or physical bond between the two supports resulting in strong adhesion between said supports and thus making it possible to secure and therefore increase the adhesion of component (C2) to component (C1). Such adhesion primers are, for example, an epoxy, a combination of epoxies, an ethyl silicate, a polyurethane, aromatic or aliphatic, and a mixture thereof, for example an aromatic or aliphatic polyurethane, an epoxy, a mixture of aromatic or aliphatic polyurethane, and epoxy.

[0142] Preferably, the overmolded composite structure does not comprise an adhesion primer selected from an epoxy, a combination of epoxides, an ethyl silicate, an aromatic or aliphatic polyurethane, and a mixture thereof, for example an aromatic or aliphatic polyurethane, an epoxy, a mixture of aromatic or aliphatic polyurethane, and epoxy. Method

[0143] The present application also relates to a method for manufacturing an overmolded composite structure according to the invention comprising a step of overmolding the component (C2) on at least a portion of a surface (S) of the component (C1). The overmolding method is known to those skilled in the art. Thus, the second component (C2) is molded in a mold containing the prefabricated component (C1). The overmolding resin composition is introduced in the molten state.

[0144] Any overmolding technique known to those skilled in the art can be implemented. Preferably, the overmolding of the method of the invention is done by injection (the overmolding resin composition is injected into the mold).

[0145] The component (C1) is manufactured before implementing the method of the invention by any technique known to those skilled in the art. A shape can be given to the component (C1) before the overmolding step.

[0146] Advantageously, the method of the invention does not include a step of assembling the components (C1) and (C2) using primary adhesion means.

[0147] Preferably, the method of the invention does not require heating of the component (C1) before the overmolding step. Preferably, the mold during the overmolding step is heated to a maximum temperature corresponding to the Tg of the matrix resin composition +40°C.

[0148] Use

[0149] The present invention also relates to the use of the overmolded composite structures described above for the manufacture of parts, particularly in the fields of mechanics, aeronautics, nautical, automotive, oil and gas (in particular offshore, gas storage), energy, health and medicine, sports and leisure and electronics.

[0150] The present invention also relates to the use of a matrix resin composition as defined above, for the preparation of an overmolded composite structure comprising a first component (C1) comprising at least one fibrous material and said matrix resin composition; and a second component (C2) comprising an overmolding resin composition, for improving the adhesion between the component (C1) and the component (C2).

[0151] The present invention also relates to the use of a matrix resin composition as defined above, for the preparation of an overmolded composite structure comprising a first component (C1) comprising at least one fibrous material and said matrix resin composition; and a second component (C2) comprising an overmolding resin composition, to obtain a peel force measured according to a protocol adapted from the ISO 4578:1997 standard (90° peel) greater than or equal to 50 N / cm, preferably greater than or equal to 70 N / cm and particularly preferred greater than or equal to 100 N / cm between the component (C1) and the component (C2).

[0152] The present invention also relates to the use of a matrix resin composition as defined above, for the preparation of an overmolded composite structure comprising a first component (C1) comprising at least one fibrous material and said matrix resin composition; and a second component (C2) comprising an overmolding resin composition, not requiring an adhesion primer between the component (C1) and the component (C2).

[0153] The invention will be explained in more detail in the following examples.

[0154] Examples

[0155] Unless otherwise stated, percentages are expressed by weight relative to the total weight of the composition.

[0156] Example 1

[0157] Preparation of components (C1) (also called composites):

[0158] The composites are all unidirectional composites, meaning that the reinforcing fibers are all oriented in the same direction. The fibers used are made up of carbon filaments with a unit diameter of 7 μm. These carbon fibers, initially made up of 24,000 filaments each, are impregnated in a process known as a powder fluidized bed, as described in WO2018 / 234436, using reactive or non-reactive polyamide 11 (PA11) powders with the same average particle size D50 = 108 μm. The powders are first supplemented with 0.1% by weight of Monarch 800 carbon black (Cabot). The prepregs obtained have an average width of 98 mm and an average thickness of 145 μm and have an average fiber content of 55% vol + / - 1% as measured by the ASTM D3171-22 standard.

[0159] The prepregs thus obtained are either used alone as component C1 at the end of the impregnation process, or they are post-crystallized under vacuum, or finally they are assembled and consolidated to make unidirectional composites by superimposing several of these prepregs in automated deposition (AFP) followed by consolidation under hot press. The consolidation time under press at the temperature plateau (above Tf, here at 210°C) allows to adjust the molar mass if a reactive resin is used. Here, we place 3 min at the consolidation plateau at 210°C, always under a pressure of 10 bar. The cooling speeds of the plates under press are also varied (from very fast by carrying out an air quenching of the sample to very slow (5°C / min)) to adjust the crystallinity rate of the composite samples.

[0160] The samples will be named as follows:

[0161] T01: prepreg from the fluidized bed impregnation process

[0162] T02: prepreg from the fluidized bed impregnation process recrystallized for 3 hours at 130°C under vacuum

[0163] P31: T01 prepregs assembled and consolidated for 3 minutes under pressure and cooled by air quenching

[0164] P32: T01 prepregs assembled and consolidated for 3 min under pressure and cooled slowly at 5°C / min

[0165] The plates thus obtained have a final thickness of 1.1 mm on average.

[0166] The composites integrated into the overmolding mold are first cut to 98 x 98 mm format 2 and dried for 24 hours under vacuum at 80°C.

[0167] Before being integrated into the overmolding mold, a 7mm wide strip of composite at the edge of the composite is covered with self-adhesive polyimide film, in order to initiate a peeling process after overmolding.

[0168] Overinjection polymers and overmolding process:

[0169] The polymer used for over-injection is BESNO TL grade polyamide 11. Over-injection was performed using a vertical press and a mold with dimensions of 100 x 100 x 2 mm3 cavity volume and central point injection. The PA11 was injected using a barrel temperature of 290°C, a mold temperature of 80°C (i.e. approximately 100°C below the melting point of the polyamide 11 used to manufacture the composite (matrix resin) or for over-injection). The holding pressure for these tests was 60% of the switching pressure and a holding time of 15s.

[0170] Characterization of composites before overmolding:

[0171] Fiber content measurement according to ASTM D3171-22: 55%vol + / - 1%vol

[0172] Measurement of the enthalpy of fusion of the matrix resin in DSC (ISO 11357-3:2013 standard)

[0173] Measurement of the molar mass Mn in GPC of the matrix resin Measurement of the viscosity of the matrix resin as mentioned above

[0174] Preparation of peel specimens and peel tests:

[0175] The overmolded plates obtained are then cut to extract peel samples measuring 98 x 15 mm. 2 , cut in the longitudinal direction of the fibers (therefore 98mm corresponds to the length of the test piece in the fiber direction).

[0176] The adhesive performance measurement was carried out using the 90° peel method adapted from the ISO4578:1997 standard described above. The assembly used is that imposed by the pulley plate and is connected to a Criterion C42 dynamometer equipped with a suitable load cell. The test is carried out at a speed of 50mm / min, with a crosshead displacement of 50mm. 5 separate specimens are analyzed for each type of overmolded component.

[0177] Results

[0178] For examples C001 to C004, the polyamide 11 powder used in the impregnation process to create component (C1) (also called composite) is a reactive PA11 powder and having the following characteristics before impregnation: melt viscosity at 240°C and at a shear of 1800 s-1 = 0.4 Pa.s, Mn = 5400 g / mol (molar mass GPC), IP = 2.1. For example C005, the polyamide 11 powder used in the impregnation process to create component (C1) (also called composite) is a non-reactive PA11 powder with the following characteristics before impregnation: melt viscosity at 240°C and at a shear of 1800 s-1 = 0.4 Pa.s, Mn = 6200 g / mol (molar mass GPC), IP = 2.1.

[0179] For example C006, the polyamide 11 powder used in the impregnation process to create component (C1) (also called composite) is a non-reactive PA11 powder with the following characteristics before impregnation: a melt viscosity at 240°C and a shear of 1800 s-1 = 1.3 Pa.s, Mn = 10100 g / mol (molar mass GPC), IP = 2.1.

[0180]

[0181] All composite data is measured before preheating the composite.

[0182] 5 The above examples show that, by comparing C001 with C005, but also C003 with C006, a higher peel force is obtained when the matrix resin of the composite before overmolding is reactive. Similarly, by comparing tests C001 to C003 and C004, we note that in the case of a matrix resin of the composite that is reactive before overmolding, we have higher peel forces if the viscosity of the matrix resin before overmolding is low, and the molar masses are low.

[0183] Example 2

[0184] Preparation of components (C1) (also called composites):

[0185] The composites are all unidirectional composites, meaning that the reinforcing fibers are all oriented in the same direction. The fibers used are made up of carbon filaments with a unit diameter of 7 μm. These carbon fibers, initially made up of 24,000 filaments each, are impregnated in a process known as a powder fluidized bed, as described in WO2018 / 234436, using polyamide 11 (PA11) powders with the same average particle size D50 = 108 μm. The powders are first supplemented with 0.1% by weight of Monarch 800 carbon black (Cabot).

[0186] The prepregs obtained (or C1 components) have an average width of 98mm and an average thickness of 145pm and have an average fiber content of 55% vol + / -1% as measured by standard ASTM D3171 - 22.

[0187] Overmolding process

[0188] The components (C1) obtained are cut to obtain test pieces with the following dimensions (LxWxH): 125x25x1.5 mm.

[0189] The test pieces are placed in a mold allowing the test pieces to be received on one side and the polymer of the overmolding composition to be injected on the other, in order to generate a contact zone between the composite substrate and the overmolded composition with a surface area of ​​25x25 mm. The representative diagram of these test pieces is shown in Figure 2 (in black the composite (C1) and in white the overmolded component (C2)).

[0190] Storage and analysis conditions

[0191] The overmolded specimens are conditioned for a minimum of 240 hours at 23°C in a sealed bag after overmolding. After opening the bag and until testing, the specimens are placed in a desiccator at room temperature.

[0192] The offset support tensile tests were carried out under conditions approaching standard NF EN 1465 (2009), the details of which are as follows: o Initial distance between the jaws: 115mm o Test speed: 1.3mm / min o Test temperature: 23°C + / - 2°C o Relative humidity: 50% + / - 10% A breaking force is measured as soon as the composite / polymer interface is broken.

[0193] The device used in the tests is a ZWICK 1455 dynamometer equipped with a 20kN cell.

[0194] The area of ​​the composite (C1) which will then be in contact with the overmolding composition (C2) can be preheated, before the overmolding step.

[0195] Overmolding is carried out at a temperature of 260°C.

[0196] The matrices implemented in the components (C1) are as follows:

[0197] 51: The PA11 powder used in the impregnation process to create component (C1) is a reactive PA11 powder with the following characteristics before impregnation: melt viscosity at 240°C and at a shear of 1800 s-1 = 0.7 Pa.s, Mn = 7500 g / mol (GPC molar mass), IP = 2.3

[0198] 52: The PA11 powder used in the impregnation process to create component (C1) is a non-reactive PA11 powder, and having the following characteristics before impregnation: melt viscosity at 240°C and at a shear of 1800 s-1 = 0.4 Pa.s, Mn = 6200 g / mol (molar mass GPC), IP = 2.1

[0199] 53: The PA11 powder used in the impregnation process to create component (C1) is a reactive PA11 powder, and having the following characteristics before impregnation: melt viscosity at 240°C and at a shear of 1800 s-1 = 0.4 Pa.s, Mn = 5400 g / mol (GPC molar mass), IP = 2.1

[0200] 54 (comparative): The PA11 powder used in the impregnation process to create component (C1) is a non-reactive PA11 powder, and having the following characteristics before impregnation: melt viscosity at 240°C and at a shear of 1800 s-1 = 205 Pa.s, Mn = 39500 g / mol (GPC molar mass), IP = 2.1

[0201] The results obtained are presented in the tables below: Table 2

[0202] Table 3

[0203] The tests show that the use of the matrix resins according to the invention in the C1 components for the preparation of overmolded composites makes it possible to obtain good adhesion without requiring preheating of the C1 component before the overmolding step. The tests also show that with preheating of the C1 component, adhesion is improved compared to an overmolded composite whose matrix resin is different from that of the invention. The comparative tests with S2 must be compared to the tests with S3

[0204] (equal viscosity). This comparison shows that the combination of molar mass and reactivity characteristics improves adhesion between the component (C1) and the overmolded component (C2).

Claims

Claims 1. Overmolded composite structure comprising: i) a first component (C1) comprising at least one fibrous material and a matrix resin composition, said matrix resin composition comprising at least one reactive thermoplastic polymer, and optionally a chain extender and / or chain limiter and / or catalyst and / or one or more additives, said thermoplastic polymer has a number-average molecular weight Mn of between 3000 and 35000 g / mol, preferably between 5000 and 20000 g / mol, preferably between 5000 and 15000 g / mol, preferentially between 5000 and 10000 g / mol; and ii) a second component (C2) comprising an overmolding resin composition, said first component (C1) comprising at least one surface (S) and said component (C2) adhering to said component (C1) on at least a portion of said surface (S).

2. Overmolded composite structure according to claim 1, in which said at least one reactive thermoplastic polymer is a polyamide, polycarbonate or polymethacrylate, preferably polyamide, and optionally comprises epoxy-type groups, preferably said reactive thermoplastic polymer is a polyamide.

3. Overmolded composite structure according to claim 1 or 2, in which said at least one reactive thermoplastic polymer is chosen from: An aliphatic polyamide selected from polyamide 6 (PA-6), polyamide 11 (PA-11), polyamide 12 (PA-12), polyamide 66 (PA-66), polyamide 46 (PA-46), polyamide 610 (PA-610), polyamide 612 (PA-612), polyamide 1010 (PA-1010), polyamide 1012 (PA-1012), polyamide 11 / 1010 and polyamide 12 / 1010, or a mixture thereof or a copolyamide thereof, and polyetheramide or polyetheresteramide (PEBA) copolymers (or polyamide block and polyether block copolymer), or a semi-aromatic polyamide is a semi-aromatic polyamide, optionally modified by urea units, in particular a PA MXD6 and a PA MXD10 or a semi-aromatic polyamide of formula A / XT in which A is chosen from a unit obtained from at least one amino acid, a unit obtained from at least one lactam and at least one unit corresponding to the formula (Ca diamine). (Cb diacid), with a representing the number of carbon atoms of the diamine and b representing the number of carbon atoms of the diacid, a and b each being between 4 and 36, advantageously between 9 and 18, the unit (Ca diamine) being chosen from aliphatic, linear or branched diamines, cycloaliphatic diamines and alkylaromatic diamines and the unit (Cb diacid) being chosen from aliphatic, linear or branched diacids, cycloaliphatic diacids and aromatic diacids; X.T denotes a unit obtained from the polycondensation of a Cx diamine and terephthalic acid, with x representing the number of carbon atoms of the Cx diamine, x being between 6 and 36, advantageously between 9 and 18, in particular a polyamide of formula A / 6T, A / 9T, A / 10T or A / 11T, A being as defined above, in particular a polyamide PA 6 / 6T, a PA 66 / 6T, a PA 6I / 6T, a PA MPMDT / 6T, a PA PA11 / 10T, a PA 11 / 6T / 10T, a PA MXDT / 10T, a PA MPMDT / 10T, a PA BACT / 10T, a PA BACT / 6T, a PA 11 / BACT, PA BACT / 10T / 6T, PA 11 / BACT / 10T, T corresponds to the acid terephthalic acid, MXD stands for m-xylylene diamine, MPMD stands for methylpentamethylene diamine, and BAC stands for 1,3-bis(aminomethyl)cyclohexane.

4. Overmolded composite structure according to any one of claims 1 to 3, in which said at least one reactive thermoplastic polymer is chosen from: - an aliphatic polyamide chosen from polyamide 11 (PA-11), polyamide 12 (PA-12), polyamide 66 (PA-66), polyamide 46 (PA-46), polyamide 610 (PA-610), polyamide 612 (PA-612), polyamide 1010 (PA-1010), polyamide 1012 (PA-1012), polyamide 11 / 1010 and polyamide 12 / 1010, or a mixture thereof or a copolyamide thereof, and polyetheramide or polyetheresteramide (PEBA) copolymers (or copolymer with polyamide blocks and polyether blocks), or - a semi-aromatic polyamide, optionally modified by urea units, in particular a PA MXD6 and a PA MXD10 or a semi-aromatic polyamide of formula A / XT in which A is chosen from a unit obtained from at least one amino acid, a unit obtained from at least one lactam and at least one unit corresponding to the formula (Ca diamine). (Cb diacid), with a representing the number of carbon atoms of the diamine and b representing the number of carbon atoms of the diacid, a and b each being between 4 and 36, advantageously between 9 and 18, the unit (Ca diamine) being chosen from linear or branched aliphatic diamines, cycloaliphatic diamines and alkylaromatic diamines and the unit (Cb diacid) being chosen from linear or branched aliphatic diacids, cycloaliphatic diacids and aromatic diacids; X.T denotes a unit obtained from the polycondensation of a Cx diamine and terephthalic acid, with x representing the number of carbon atoms of the Cx diamine, x being between 6 and 36, advantageously between 9 and 18, in particular a polyamide of formula A / 6T, A / 9T, A / 10T or A / 11T, A being as defined above, in particular a polyamide PA 6 / 6T, a PA 66 / 6T, a PA 6I / 6T, a PA MPMDT / 6T, a PA PA11 / 10T, a PA 11 / 6T / 10T, a PA MXDT / 10T, a PA MPMDT / 10T, a PA BACT / 10T, a PA BACT / 6T, a PA 11 / BACT, PA BACT / 10T / 6T, PA 11 / BACT / 10T, T corresponds to the acid terephthalic acid, MXD stands for m-xylylene diamine, MPMD stands for methylpentamethylene diamine, and BAC stands for 1,3-bis(aminomethyl)cyclohexane.

5. Overmolded composite structure according to any one of claims 1 to 4, wherein the reactive thermoplastic polymer is a semi-aromatic polyamide chosen from a PA MPMDT / 6T, a PA PA11 / 10T, a PA 11 / BACT, a PA 11 / 6T / 10T, a PA MXDT / 10T, a PA MPMDT / 10T, a PA BACT / 10T, a PA BACT / 6T, PA BACT / 10T / 6T, a PA 11 / BACT / 6T, PA 11 / MPMDT / 10T, PA 11 / BACT / 10T, a PA 11 / MXDT / 10T.

6. Overmolded composite structure according to any one of claims 1 to 4, in which the reactive thermoplastic polymer is PA11 or PA12, preferably PA11.

7. Overmolded composite structure according to any one of claims 1 to 6, in which the overmolding resin composition is identical to or different from the matrix resin, preferably it comprises an aliphatic or semi-aromatic polyamide polymer as defined according to one of claims 3 to 6.

8. Overmolded composite structure according to any one of claims 1 to 7, in which the fibrous material comprises continuous fibers selected from: - fibers of mineral origin such as carbon, glass, silicon carbide, basalt, silica fibers; - fibres of plant origin, in particular fibres based on flax, hemp, lignin, bamboo, silk, in particular spider silk or sisal, cellulose fibres, in particular viscose; - fibers of organic origin such as amorphous thermoplastic fibers with a glass transition temperature Tg greater than the Tg of the polymer of the matrix resin composition when the latter is amorphous or greater than the Tf of the polymer of the matrix resin composition when the latter is semi-crystalline and whose Tg (in the case of an amorphous material) or Tf (in the case of a semi-crystalline material) is greater than the injection temperature of the overmolding resin composition, or semi-crystalline thermoplastic fibers with a melting temperature Tf greater than the Tg of the polymer of the matrix resin composition when the latter is amorphous or greater than the Tf of the polymer of the matrix resin composition and whose Tg (in the case of an amorphous material) or Tf (in the case of a semi-crystalline material) is greater than the injection temperature of the overmolding resin composition, or a mixture of two or of several of said fibers,preferably a mixture of carbon, glass or silicon carbide fibers, in particular carbon fibers, or mixtures thereof., 9. Overmolded composite structure according to any one of claims 1 to 8, characterized in that it does not comprise an adhesion primer between components C1 and C2.

10. An overmolded composite structure according to any one of claims 1 to 9, wherein the matrix resin composition does not comprise a filler or comprises less than 2% by weight of filler, preferably 0.01 at 0.5% by weight of filler relative to the weight of the matrix resin composition.

11. Overmolded composite structure according to any one of claims 1 to 10, in which the reactive thermoplastic polymer has a melt viscosity measured by capillary rheology, measured at Tf+50°C, Tf being the melting temperature of the at least one polyamide, at a shear of 1800 s-1 of between 0.05 and 1000 Pa.s, preferably between 0.1 and 1000 Pa.s, preferably between 0.3 and 1000 Pa.s, preferably between 0.3 and 500 Pa.s, more preferably between 0.3 and 250 Pa.s, for example between 0.3 and 100 Pa.s, even more preferably between 0.3 and 50 Pa.s, more preferably between 0.3 and 25 Pa.s, even more preferably between 0.3 and 10 Pa.s, preferably between 0.3 and 10 ... and 5 Pa.s.

12. Overmolded composite structure according to any one of claims 1 to 11, in which the reactive thermoplastic polymer is an amorphous polyamide or a semi-crystalline polyamide having an absolute enthalpy of fusion in the component (C1) before overmolding of less than 12 J / g of matrix resin, preferably less than 8 J / g of matrix resin, preferably less than 5 J / g of matrix resin, calculated according to equation (1) Equation (1): the enthalpy measurement being carried out by differential scanning calorimetry (DSC) according to the ISO 11357-3 standard of 2013, the melting and crystallization peaks being the first heating peaks at a rate of 20 K / min.

13. Overmolded composite structure according to any one of claims 1 to 12, in which: - the matrix resin comprises an aliphatic polyamide, preferably PA11 or PA12, preferably PA11, and the overmolding resin a PEBA; or - the matrix resin comprises an aliphatic polyamide, preferably PA11 or PA12, preferably PA11, and the overmolding resin an aliphatic polyamide, preferably PA11 or PA12, preferably PA11; or - the matrix resin comprises an aliphatic polyamide, preferably PA11 or PA12, preferably PA11, and the overmolding resin a semi-aromatic polyamide; or - the matrix resin comprises a semi-aromatic polyamide and the overmolding resin an aliphatic polyamide, preferably PA11 or PA12, preferably PA11.

14. Method for manufacturing an overmolded composite structure according to any one of claims 1 to 13, comprising a step of overmolding the component C2 on at least a portion of the surface S of the component C1.

15. The method of claim 14, wherein the overmolding step is an injection overmolding step.

16. Use of the overmolded composite structures according to any one of claims 1 to 11 for the manufacture of parts, particularly in the fields of mechanics, aeronautics, nautical, automotive, oil and gas (in particular offshore, gas storage), energy, health and medicine, sports and leisure and electronics.

17. Use of a matrix resin composition as defined in claims 1 to 6, and 10 to 13, for the preparation of an overmolded composite structure comprising a first component (C1) comprising at least one fibrous material and said matrix resin composition; and a second component (C2) comprising an overmolding resin composition, to obtain a peel force measured according to a protocol adapted from the ISO 4578:1997 standard (90° peel) greater than or equal to 50 N / cm, preferably greater than or equal to 70 N / cm and particularly preferred greater than or equal to 100 N / cm between the component (C1) and the component (C2).

Images