Multilayer structures for transporting or storing hydrogen

Abstract

The present invention relates to a multi-layer structure for transporting, distributing and storing hydrogen, in particular for storing hydrogen, comprising, from the inside to the outside, at least one sealing layer (1) and at least one composite reinforcing layer (2), said innermost composite reinforcing layer (2) being welded to said outermost adjacent sealing layer (1), said sealing layer (1) being predominantly composed of at least one semi-crystalline polyamide thermoplastic polymer P1i, i=1 to n, n being the number of sealing layers excluding amide polyether blocks (PEBA), up to 50% by weight of an impact modifier, in particular less than 15% by weight, relative to the total weight of the composition. %, in particular up to 12% by weight of impact modifier, and up to 1.5% by weight of plasticizer relative to the total weight of the composition, wherein the at least one polyamide thermoplastic polymer of each sealing layer may be the same or different, and at least one of said composite reinforcing layers consists of a fibrous material in the form of continuous fibers impregnated with a composition comprising predominantly at least one semi-crystalline polyamide polymer P2j, j=1 to m, m being the number of reinforcing layers, and wherein the number of carbon atoms per amide functional group of the polyamide of the outermost adjacent sealing layer (1) differs by up to 20% from the number of carbon atoms of the polyamide of the innermost reinforcing layer (2).

Description

[Technical Field]

[0001] FIELD OF THE INVENTION This patent application relates to multi-layer composite structures for transporting, distributing or storing hydrogen, particularly for distributing or storing hydrogen, and methods for producing same. [Background technology]

[0002] Hydrogen tanks are currently attracting a great deal of attention from numerous manufacturers, particularly in the automotive sector. One of the desired goals is to propose even more low-emission vehicles. Thus, the aim is for electric or hybrid vehicles that include batteries to gradually replace internal combustion engine vehicles, such as gasoline or diesel vehicles. Batteries have proven to be relatively complex vehicle components. Depending on the battery's positioning in the vehicle, it may need to be protected from impacts and from the external environment, which may have very high temperatures and variable humidity. It may also be necessary to avoid any risk of fire.

[0003] Furthermore, it is important that their operating temperature does not exceed 55°C in order not to damage the battery cells and prolong their lifespan. Conversely, in winter, for example, it may be necessary to increase the battery temperature to optimize its operation.

[0004] Furthermore, electric vehicles today still suffer from several problems, namely battery range, the use of rare earth metals in these batteries, which are not infinite resources, charging times that are much longer than the length of time it takes to fill the tank, and problems in various countries with generating electricity to allow the batteries to be charged.

[0005] Hydrogen is therefore a substitute for electric batteries as hydrogen can be converted into electricity by fuel cells, thus powering electric vehicles.

[0006] Hydrogen tanks usually consist of a metal liner (or sealing layer) that must prevent hydrogen from permeating. One type of tank envisaged is called Type IV, which is based on a thermoplastic liner with a composite wrapped around it.

[0007] Its basic principle is to separate the two essential functions of sealing and mechanical strength and to manage them independently of each other. In this type of tank, a liner (or sealing sheath) made of thermoplastic resin is combined with a reinforcing structure, also known as a reinforcing sheath or layer, consisting of fibers (glass, aramid, carbon) wrapped in a thermoplastic or thermosetting matrix, which allows it to operate at much higher pressures while reducing its weight and avoiding the risk of explosion in case of a severe external attack.

[0008] The liner has the following principle characteristics: Can be converted by extrusion blow molding, rotational molding, injection molding or extrusion Low hydrogen permeability, and indeed the permeability of the liner, is an important factor in limiting hydrogen leakage from the tank. Good mechanical properties (fatigue) at low temperatures (-40 to -70°C), It must be heat resistant up to 120°C.

[0009] In fact, it is necessary to increase the filling rate of hydrogen tanks, which should be roughly equivalent to that of fuel tanks for internal combustion engines (about 3 to 5 minutes), but this increase in rate causes more significant heating of the tank, which then reaches temperatures of about 100°C.

[0010] First generation Type IV tanks used high density polyethylene (HDPE) based liners.

[0011] However, HDPE has the drawback of having a melting point that is too low and a hydrogen permeability that is too high, which presents a problem with new requirements in terms of heat resistance and does not make it possible to increase the filling speed of the tank.

[0012] Polyamide PA6-based liners have been under development for many years.

[0013] Nevertheless, PA6 has the drawback of having low resistance to cold.

[0014] WO18155491 describes a hydrogen transport component having a three-layer structure, the inner layer of which is a composition consisting of PA11, 15 to 50% impact modifier, and 1 to 3% plasticizer, or lacking plasticizer, the composition having hydrogen barrier properties, good flexibility and durability at low temperatures. However, this structure is suitable for pipes for transporting hydrogen, but not for storing hydrogen.

[0015] Therefore, on the one hand, there is a need to optimize the matrix of the composite so as to optimize its mechanical strength at high temperatures, and on the other hand, there remains a need to optimize the materials comprising the sealing sheath so as to optimize the operating temperature of the sealing sheath. Thus, any optional changes made to the materials of the composition comprising the sealing liner should not cause a significant increase in the manufacturing temperature of this liner (extrusion blow molding, injection molding, rotational molding, etc.) compared to those practiced today. Summary of the Invention

[0016] These problems are solved by providing a multi-layer structure of the present invention that is adapted to transport, distribute or store hydrogen.

[0017] Throughout this specification, the terms "liner" and "sealing sheath" have the same meaning.

[0018] The present invention therefore provides a multi-layer structure adapted for transporting, distributing and storing hydrogen, in particular for storing it, comprising: From the inside to the outside, it comprises at least one sealing layer (1) and at least one composite reinforcing layer (2), the innermost composite reinforcing layer (2) is welded to the outermost adjacent sealing layer (1); The sealing layer (1) is made of a composition, and the composition is at least one semi-crystalline polyamide thermoplastic polymer P1i, where i=1 to n and n is the number of sealing layers excluding polyether block amide (PEBA), up to 50% by weight of impact modifier, in particular up to 15% by weight of impact modifier, particularly up to 12% by weight of impact modifier, relative to the total weight of the composition; Mainly comprising up to 1.5% by weight of a plasticizer relative to the total weight of the composition, the at least one polyamide thermoplastic polymer in each sealing layer may be the same or different; at least one of the composite reinforcing layers consists of a fibrous material in the form of continuous fibers impregnated with a composition comprising predominantly at least one semi-crystalline polyamide polymer P2j, j=1 to m, m being the number of reinforcing layers; The multilayer structure relates to a multilayer structure in which the number of carbon atoms per amide functional group of the polyamide of the outermost adjacent sealing layer (1) differs by up to 20% from the number of carbon atoms of the polyamide of the innermost reinforcing layer (2).

[0019] The inventors have therefore unexpectedly found that the use of a semi-crystalline polyamide thermoplastic polymer P1i, in particular a short- or long-chain semi-crystalline polyamide thermoplastic polymer P1i, comprising limited proportions of impact modifiers and plasticizers, for the sealing layer, and a semi-crystalline thermoplastic polymer P2j for the matrix of a composite material, said composite material being fused to the sealing layer, and the two polymers P1i and P2j of the sealing layer adjacent to the composite reinforcing layer differing in the number of carbon atoms per amide function by at most 20%, makes it possible to achieve structures suitable for transporting, distributing or storing hydrogen, in particular structures suitable for storing hydrogen, and an increase in the maximum use temperature, which may be up to 120°C, and therefore makes it possible to increase the filling speed of the tank. DETAILED DESCRIPTION OF THE INVENTION

[0020] "Multi-layer structure" means a tank that comprises or consists of several layers, i.e. several sealing layers and several reinforcing layers, or one sealing layer and several reinforcing layers, or several sealing layers and one reinforcing layer, or one sealing layer and one reinforcing layer.

[0021] Multilayer structures are therefore understood to exclude pipes or tubes.

[0022] Polyether block amides (PEBA) are copolymers having amide units (Ba1) and polyether units (Ba2), the amide units (Ba1) being units derived from at least one amino acid, or units derived from at least one lactam, or: - the polycondensation of at least one diamine, said diamine being preferentially chosen from linear or branched aliphatic diamines, or mixtures thereof, and - corresponding to aliphatic repeating units chosen from units XY resulting from the polycondensation of at least one carboxylic diacid, said diacid being preferentially chosen from linear or branched aliphatic diacids, or mixtures thereof, said diamine and said diacid containing from 4 to 36 carbon atoms, advantageously from 6 to 18 carbon atoms; Said polyether units (Ba2) are in particular derived from at least one polyalkylene ether polyol, in particular a polyalkylene ether diol.In one embodiment, the composition of said components of said sealing layer is devoid of a nucleating agent.

[0023] Nucleating agents are known to those skilled in the art, and the term refers to a substance that, when incorporated into a polymer, forms nuclei for growing crystals in the molten polymer.

[0024] These may be chosen, for example, from microtalc, carbon black, silica, titanium dioxide and nanoclay.

[0025] In another embodiment, the component composition of the sealing layer is devoid of nucleating agents and plasticizers.

[0026] In one embodiment, the structure also lacks an outermost layer adjacent to the outermost layer of composite reinforcement made of polyamide polymer.

[0027] In one embodiment, the multi-layer structure consists of only two layers, a sealing layer and a reinforcing layer.

[0028] The sealing layer or layers are the innermost layers relative to the composite reinforcing layer which is the outermost layer.

[0029] The tanks may be tanks for mobile storage of hydrogen, i.e. on trucks for transporting hydrogen, on vehicles for transporting hydrogen and supplying hydrogen-based fuel cells, for example on trains for supplying hydrogen, or on drones for supplying hydrogen, but may also be tanks for fixed storage of hydrogen at depots for distributing hydrogen to vehicles.

[0030] Advantageously, the sealing layer (1) is hydrogen leak-tight at 23°C, i.e. the hydrogen permeability at 23°C is less than 500 cc.mm / m2.24h.atm at 23°C under 0% relative humidity (RH).

[0031] In one embodiment, the one or more sealing layers are primarily at least one polyamide thermoplastic polymer P1i, where i=1 to n, n being the number of sealing layers excluding polyether block amide (PEBA) and excluding PA11, and which is semi-crystalline; The composition comprises:

[0032] The composite reinforcing layer(s) are wrapped around the sealing layer by ribbons (or tapes or rovings) of polymer-impregnated fibers, which are deposited, for example, by filament winding.

[0033] If several layers are present, the polymers may be different.

[0034] If the polymer of the reinforcing layer is the same, there can be several layers, but advantageously there is a single reinforcing layer, this reinforcing layer having at least one complete turn around the sealing layer.

[0035] Even if there is a single layer, several successive complete wraps can be made around the sealing layer to make up said single layer.

[0036] This fully automated process, well known to those skilled in the art, makes it possible to select, layer by layer, the wrap angle that gives the final structure the ability to withstand internal pressure loads.

[0037] If several sealing layers are present, only the innermost sealing layer is in direct contact with hydrogen.

[0038] If there is only one sealing layer and composite reinforcing layer, then there is a multi-layer structure of two layers, and these two layers are then welded together, i.e., in direct contact with each other and adhered to each other.

[0039] If several sealing layers and / or several composite reinforcing layers are present, the outermost layer of said sealing layer, and therefore the layer opposite the layer in contact with hydrogen, is welded to the innermost layer of said composite reinforcing layer and is therefore in direct contact with and adheres to each other.

[0040] The other composite reinforcing layers are also bonded to one another.

[0041] The other sealing layers also adhere to each other.

[0042] Advantageously, there is only one sealing layer and one reinforcing layer, which are not welded to each other.

[0043] Regarding the sealing layer(s) and the thermoplastic polymer P1i There may be one or more sealing layers.

[0044] Each of said layers consists of a composition mainly comprising at least one thermoplastic polymer P1i, where i corresponds to the number of layers present and i is from 1 to 10, in particular from 1 to 5, in particular from 1 to 3, and preferentially i=1.

[0045] The term "predominantly" means that said at least one polymer is present in more than 50% by weight relative to the total weight of the composition.

[0046] Advantageously, said at least one predominant polymer is present in an amount greater than 60% by weight, in particular greater than 70% by weight, particularly greater than 80% by weight and more particularly greater than or equal to 90% by weight, relative to the total weight of the composition.

[0047] The composition may also contain up to 50% by weight of impact modifiers and / or plasticizers and / or additives, relative to the total weight of the composition.

[0048] The additive may be selected from another polymer, an antioxidant, a heat stabilizer, a UV absorber, a light stabilizer, a lubricant, an inorganic filler, a flame retardant, a pigment, carbon black, and a carbonaceous nanofiller; in particular, the additive is selected from an antioxidant, a heat stabilizer, a UV absorber, a light stabilizer, a lubricant, an inorganic filler, a flame retardant, a pigment, carbon black, and a carbonaceous nanofiller.

[0049] In one embodiment, nucleating agents are excluded from the additives.

[0050] In another embodiment, nucleating agents are excluded from the additives, in which case the composition also lacks plasticizers.

[0051] Said other polymer may be another semi-crystalline thermoplastic polymer or a different polymer, especially EVOH (ethylene vinyl alcohol).

[0052] Advantageously, said composition comprises mainly said thermoplastic polymer P1i, from 0 to 50% by weight of impact modifier, in particular from 0 to less than 15% of impact modifier, in particular from 0 to 12% of impact modifier, from 0 to 1.5% of plasticizer and from 0 to 5% by weight of additives, the sum of the constituents of the composition being equal to 100%.

[0053] Advantageously, said composition consists mainly of said thermoplastic polymer P1i, from 0 to 50% by weight of impact modifier, in particular from 0 to less than 15% of impact modifier, in particular from 0 to 12% of impact modifier, from 0 to 1.5% of plasticizer and from 0 to 5% by weight of additives, the sum of the constituents of the composition being equal to 100%.

[0054] Advantageously, said composition comprises mainly said thermoplastic polymer P1i, from 0 to 50% by weight of impact modifier, in particular from 0 to less than 15% of impact modifier, in particular from 0 to 12% of impact modifier, from 0 to 1.5% of plasticizer and from 0 to 5% by weight of additives, the sum of the constituents of the composition being equal to 100%.

[0055] Advantageously, said composition consists mainly of said thermoplastic polymer P1i, from 0 to 50% by weight of impact modifier, in particular from 0 to less than 15% of impact modifier, in particular from 0 to 12% of impact modifier, from 0 to 1.5% of plasticizer and from 0 to 5% by weight of additives, the sum of the constituents of the composition being equal to 100%.

[0056] Advantageously, said composition comprises mainly said thermoplastic polymer P1i, from 0 to 50% by weight of impact modifier, in particular from 0 to less than 15% of impact modifier, in particular from 0 to 12% of impact modifier, from 0 to 5% of plasticizer and from 0 to 5% by weight of additives, the sum of the constituents of the composition being equal to 100%.

[0057] Advantageously, said composition consists mainly of said thermoplastic polymer P1i, from 0 to 50% by weight of impact modifier, in particular from 0 to less than 15% of impact modifier, in particular from 0 to 12% of impact modifier, from 0 to 5% of plasticizer and from 0 to 5% by weight of additives, the sum of the constituents of the composition being equal to 100%.

[0058] The at least one predominant polymer in each layer may be the same or different.

[0059] In one embodiment, a single predominant polymer is present in at least the sealing layer that is adhered to the composite reinforcing layer.

[0060] In one embodiment, the composition comprises from 0.1 to 50 wt. %, especially from 0.1 to less than 15 wt. %, and particularly from 0.1 to 12 wt. %, of impact modifier relative to the total weight of the composition.

[0061] In one embodiment, the composition lacks a plasticizer.

[0062] In another embodiment, the composition comprises from 0.1 to 50 wt. %, especially from 0.1 to less than 15 wt. %, and particularly from 0.1 to 12 wt. %, of impact modifier, relative to the total weight of the composition, and the composition is devoid of plasticizer.

[0063] In yet another embodiment, the composition comprises from 0.1 to 50 wt. % of impact modifier, in particular from 0.1 to less than 15 wt. % of impact modifier and from 0.1 to 1.5 wt. % of plasticizer, relative to the total weight of the composition.

[0064] Semicrystalline Polyamide Thermoplastic Polymer P1i "Thermoplastic" or "semi-crystalline polyamide thermoplastic polymer" refers to a material that is generally solid at ambient temperature, softens during temperature increase, in particular after passing its glass transition temperature (Tg), can exhibit true melting above a temperature called the melting point (Tm), and becomes solid again when the temperature falls below its crystallization temperature.

[0065] Tg, Tc and Tm are determined by differential scanning calorimetry (DSC) according to standards 11357-2:2013 and 11357-3:2013, respectively.

[0066] The number average molecular weight Mn of said semicrystalline polyamide thermoplastic polymer preferably ranges from 10,000 to 85,000, in particular from 10,000 to 60,000, preferentially from 10,000 to 50,000, and even more preferentially from 12,000 to 50,000. These Mn values ​​may correspond to an intrinsic viscosity of 0.8 or greater, determined in m-cresol according to standard ISO 307:2007, but by changing the solvent (m-cresol instead of sulfuric acid, the temperature being 20° C.).

[0067] The nomenclature used to define polyamides is set out in ISO standard 1874-1:2011 "Plastiques - Materiaux polyamides (PA) pour moulage et extrusion - Partie 1: Designation", in particular on page 3 (Tables 1 and 2), and is well known to those skilled in the art.

[0068] The polyamide may be a homopolyamide or a copolyamide or a mixture thereof.

[0069] In one embodiment, the thermoplastic polymer is a short-chain semi-crystalline aliphatic polyamide, i.e., a polyamide with an average number of up to 9 carbon atoms per nitrogen atom, or a long-chain aliphatic polyamide, i.e., a polyamide with an average number of more than 9, preferably more than 10, carbon atoms per nitrogen atom.

[0070] In particular, the short-chain aliphatic polyamide is selected from PA6, PA610, PA612, and PA6 / polyolefin mixtures.

[0071] In particular, the long-chain aliphatic polyamide is chosen from polyamide 11 (PA11), polyamide 12 (PA12), polyamide 1010 (PA1010), polyamide 1012 (PA1012), polyamide 1212 (PA1012), or mixtures or copolyamides thereof, in particular PA11 and PA12.

[0072] In one embodiment, the long chain aliphatic polyamide is selected from polyamide 12 (PA12), polyamide 1010 (PA1010), polyamide 1012 (PA1012), polyamide 1212 (PA1012), or mixtures or copolyamides thereof, in particular PA12.

[0073] In another embodiment, the semi-crystalline polyamide thermoplastic polymer is a semi-crystalline, semi-aromatic polyamide, in particular a semi-crystalline, semi-aromatic polyamide having an average number of more than 8, preferably more than 9, carbon atoms per nitrogen atom and a melting temperature of 240°C to less than 280°C.

[0074] Advantageously, the semicrystalline polyamide is a semi-aromatic polyamide, in particular a semi-aromatic polyamide of formula X / YAr as described in EP 1 505 099, in particular a semi-aromatic polyamide of formula A / XT, in which A is selected from units resulting from amino acids, units resulting from lactams, and units corresponding to the formula (Ca diamine).(Cb diacid), a represents the number of carbon atoms in the diamine, b represents the number of carbon atoms in the diacid, a and b each being between 4 and 36, advantageously between 9 and 18, in which the units (Ca diamine) are selected from linear or branched aliphatic diamines, cycloaliphatic diamines and alkylaromatic diamines, and the units (Cb diacid) are selected from linear or branched aliphatic diacids, cycloaliphatic diacids and aromatic diacids.

[0075] XT denotes a unit resulting from the polycondensation of a Cx diamine and terephthalic acid, x representing the number of carbon atoms in the Cx diamine, x being between 5 and 36, advantageously between 9 and 18, and in particular polyamides having the formula A / 5T, A / 6T, A / 9T, A / 10T or A / 11T, A being as defined above, in particular polyamides such as PA MPMDT / 6T, PA11 / 10T, PA 5T / 10T, PA 11 / BACT, PA 11 / 6T / 10T, PA MXDT / 10T, PA MPMDT / 10T, PA BACT / 10T, PA BACT / 6T, PA BACT / 10T / 6T, PA 11 / BACT / 6T, PA 11 / MPMDT / 6T, PA 11 / MPMDT / 10T, PA 11 / BACT / 10T, PA Select from 11 / MXDT / 10T or 11 / 5T / 10T.

[0076] In particular, the semi-aromatic semi-crystalline polyamide is selected from polyamide 11 / 5T or 11 / 6T or 11 / 10T, MXDT / 10T, MPMDT / 10T and BACT / 10T.

[0077] T corresponds to terephthalic acid, MXD corresponds to m-xylylenediamine, MPMD corresponds to methylpentamethylenediamine and BAC corresponds to bis(aminomethyl)cyclohexane. The semi-aromatic polyamides defined above have in particular a Tg of greater than or equal to 80° C.

[0078] Advantageously, each sealing layer consists of a composition comprising the same type of polyamide.

[0079] The composition comprising the polymer P1i may be black and may absorb radiation suitable for welding after wrapping the composite reinforcing layer around the sealing layer.

[0080] If welding is required, there are various methods that make it possible to weld elements made of polyamide thermoplastic polymer: thus, contact or non-contact heated blades, ultrasonic, infrared, induction, vibration, rotation to weld one element to another, or even laser welding can be used.

[0081] Welding polyamide thermoplastic polymer elements, particularly by laser welding, can require that the two elements to be welded have different properties with respect to radiation, particularly laser radiation: one of the elements must be transparent to radiation, particularly laser radiation, and the other must absorb radiation, particularly laser radiation. The radiation, particularly laser radiation, passes through the transparent part and then reaches the absorbing element, where it is converted into heat. This melts the contact area between the two elements, thus causing welding to occur.

[0082] In the case of carbon fibers, the preferred case is to melt the interface upon removal.

[0083] To make them absorbent, it is known to add various additives, including for example carbon black, which gives the polymer a black colour and allows it to absorb radiation suitable for welding.

[0084] In one embodiment, welding is performed by a system selected from laser, infrared (IR) heating, LED heating, induction or microwave heating, or radio frequency (HF) heating.

[0085] If the welding is carried out by laser welding, the composition P1i comprises a carbonaceous filler.

[0086] If the welding is carried out by induction, the composition P1i comprises metal particles.

[0087] Advantageously, the welding is carried out by a laser system.

[0088] Regarding impact modifiers The impact modifier can be any impact modifier, so long as it is a polymer that has a modulus below that of the resin and has good adhesion to the matrix so as to dissipate crack energy.

[0089] The impact modifier advantageously consists of a polymer, in particular a polyolefin, having a flexural modulus of less than 100 MPa, measured according to standard ISO 178, and a Tg of less than 0°C (measured according to standard 11357-2 at the inflection point of the DSC thermogram).

[0090] In one embodiment, PEBA is excluded from the definition of impact modifier.

[0091] The polyolefins of the impact modifier may be functionalized or non-functionalized, or may be a mixture of at least one functionalized polyolefin and / or at least one non-functionalized polyolefin. For simplicity, polyolefins are designated (B), functionalized polyolefins are designated (B1), and non-functionalized polyolefins are designated (B2) below.

[0092] Non-functionalized polyolefins (B2) are classically homopolymers or copolymers of alpha-olefins or diolefins, such as ethylene, propylene, 1-butene, 1-octene, butadiene. By way of example, the following may be mentioned: - polyethylene, in particular homopolymers and copolymers of LDPE, HDPE, LLDPE (linear low density polyethylene), VLDPE (very low density polyethylene) and metallocene polyethylene; - propylene homopolymers or copolymers, - ethylene / alpha-olefin copolymers, such as ethylene / propylene, EPR (short for ethylene-propylene-rubber) and ethylene / propylene / diene (EPDM); - styrene / ethylene-butene / styrene (SEBS), styrene / butadiene / styrene (SBS), styrene / isoprene / styrene (SIS), styrene / ethylene-propylene / styrene (SEPS) block copolymers, - copolymers of ethylene and at least one product chosen from salts or esters of unsaturated carboxylic acids, such as alkyl (meth)acrylates (for example methyl acrylate), or vinyl esters of saturated carboxylic acids, such as vinyl acetate (EVA), in which the proportion of comonomers can reach 40% by weight.

[0093] The functionalized polyolefin (B1) can be a polymer of alpha-olefins having reactive units (functional groups), such as acid, anhydride, or epoxy functional groups. By way of example, mention may be made of the aforementioned polyolefin (B2) grafted or copolymerized or terpolymerized with unsaturated epoxides, such as glycidyl (meth)acrylate, or with carboxylic acids or their corresponding salts or esters, such as (meth)acrylic acid (which can be fully or partially neutralized with metals, such as Zn), or even with carboxylic anhydrides, such as maleic anhydride. The functionalized polyolefin can be, for example, a PE / EPR mixture, the weight ratio of which can vary widely, for example, from 40 / 60 to 90 / 10, and which is cografted with an anhydride, especially maleic anhydride, according to a grafting rate of, for example, 0.01 to 5% by weight.

[0094] The functionalized polyolefin (B1) may be chosen from the following maleic anhydride or glycidyl methacrylate grafted (co)polymers, the grafting rate being, for example, between 0.01 and 5% by weight: PE, PP, copolymers of ethylene and propylene, butene, hexene or octene, containing, for example, 35 to 80% by weight of ethylene; - ethylene / alpha-olefin copolymers, such as ethylene / propylene, EPR (short for ethylene-propylene-rubber) and ethylene / propylene / diene (EPDM); - styrene / ethylene-butene / styrene (SEBS), styrene / butadiene / styrene (SBS), styrene / isoprene / styrene (SIS), styrene / ethylene-propylene / styrene (SEPS) block copolymers, - ethylene and vinyl acetate copolymers (EVA), containing up to 40% by weight of vinyl acetate; - ethylene and alkyl(meth)acrylate copolymers containing up to 40% by weight of alkyl(meth)acrylate; - Ethylene and vinyl acetate (EVA) and alkyl (meth)acrylate copolymers containing up to 40% by weight of comonomer.

[0095] The functionalized polyolefins (B1) may also be selected from ethylene / propylene copolymers, mainly with propylene grafted with maleic anhydride, condensed with monoamine polyamides (or polyamide oligomers) (products described in EP-A-0,342,066).

[0096] The functionalized polyolefin (B1) can also be a co- or terpolymer of at least the following units: (1) ethylene, (2) alkyl (meth)acrylate or vinyl ester of a saturated carboxylic acid, and (3) anhydride, such as maleic anhydride or (meth)acrylic acid, or an epoxy, such as glycidyl (meth)acrylate.

[0097] As examples of functionalized polyolefins of the latter type, the following copolymers may be mentioned, in which ethylene is preferably equal to at least 60% by weight and the termonomer (functional group) is, for example, equal to 0.1 to 10% by weight of the copolymer: ethylene / alkyl (meth)acrylate / (meth)acrylic acid or maleic anhydride or glycidyl methacrylate copolymers, - ethylene / vinyl acetate / maleic anhydride or glycidyl methacrylate copolymers, - Ethylene / vinyl acetate or alkyl (meth)acrylate / (meth)acrylic acid or maleic anhydride or glycidyl methacrylate copolymers.

[0098] In the aforementioned copolymers, the (meth)acrylic acid may be salified with Zn or Li.

[0099] The term "alkyl (meth)acrylate" in (B1) or (B2) denotes C1 to C8 alkyl methacrylates and acrylates, and may be selected from methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, 2-ethyl-hexyl acrylate, cyclohexyl acrylate, methyl methacrylate, and ethyl methacrylate.

[0100] Furthermore, the previously cited polyolefins (B1) may also be crosslinked by any suitable method or agent (diepoxy, diacid, peroxide), and the term functionalized polyolefin also includes mixtures of the previously cited polyolefins with difunctional agents capable of reacting therewith, such as diacids, dianhydrides, diepoxy, or mixtures of at least two functionalized polyolefins capable of reacting together.

[0101] The copolymers (B1) and (B2) referred to above may be copolymerized in a statistical or sequential manner and have a linear or branched structure.

[0102] The molecular weight, index MFI, and density of these polyolefins may also vary widely, as will be appreciated by those skilled in the art. MFI, short for Melt Flow Index, is a measure of the fluidity of a polymer in the molten state. It is measured according to standard ASTM 1238.

[0103] Advantageously, the non-functionalized polyolefin (B2) is selected from homopolymers or copolymers of polypropylene and any ethylene homopolymer or copolymer and higher alpha-olefin comonomers, such as butene, hexene, octene or 4-methyl-1-pentene. Mention may be made, for example, of PP, high density PE, medium density PE, linear low density PE, low density PE and very low density PE. These polyethylenes are known to those skilled in the art as being produced according to the "free radical" process, according to the "Ziegler" catalysis process or, more recently, by "metallocene" catalysis.

[0104] Advantageously, the functionalized polyolefin (B1) is selected from any polymer containing alpha-olefin units and units carrying polar reactive functional groups, such as epoxy, carboxylic acid, or carboxylic acid anhydride functional groups. Examples of such polymers include terpolymers of ethylene, alkyl acrylate, and maleic anhydride or glycidyl methacrylate, such as Lotader® from the applicant, or polyolefins grafted with maleic anhydride, such as Orevac® from the applicant, and terpolymers of ethylene, alkyl acrylate, and (meth)acrylic acid. Mention may also be made of homopolymers or copolymers of polypropylene grafted with carboxylic acid anhydrides and then condensed with polyamide or monoamine polyamide oligomers.

[0105] Advantageously, the composition constituting the sealing layer(s) is devoid of polyether block amide (PEBA), in this embodiment PEBA is therefore excluded from the impact modifiers.

[0106] Advantageously, said permeable composition is devoid of core-shell particles or core-shell polymers.

[0107] Core-shell particles are to be understood as particles in which the first layer forms the nucleus and the second and all subsequent layers form the respective shells.

[0108] The core-shell particles are obtained by a process having several steps, including at least two steps, such a process being described, for example, in document US 2009 / 0149600 or EP 0,722,961.

[0109] Regarding plasticizers The plasticizer may be any plasticizer commonly used in polyamide(s) based compositions.

[0110] Advantageously, plasticizers are used that have good thermal stability so as not to form fumes during the steps of mixing the different polymers and converting the resulting composition.

[0111] In particular, the plasticizer is benzenesulfonamide derivatives, such as the ortho and para isomers of n-butylbenzenesulfonamide (BBSA), ethyltoluenesulfonamide (ETSA), N-cyclohexyltoluenesulfonamide and N-(2-hydroxypropyl)benzenesulfonamide (HP-BSA); Hydroxybenzoic acid esters, such as 2-ethylhexyl parahydroxybenzoate (EHPB) and 2-decylhexyl parahydroxybenzoate (HDPB), an ester or ether of tetrahydrofurfuryl alcohol, for example oligoethyleneoxytetrahydrofurfuryl alcohol; Esters of citric acid or hydroxymalonic acid, such as oligoethyleneoxymalonate may be selected from:

[0112] A preferred plasticizer is n-butylbenzenesulfonamide (BBSA).

[0113] Another, more particularly preferred, plasticizer is N-(2-hydroxypropyl)benzenesulfonamide (HP-BSA). Indeed, the latter has the advantage of preventing the formation of deposits ("scum") in the extrusion screw and / or die during the conversion step by extrusion.

[0114] Of course, it is possible to use mixtures of plasticizers.

[0115] Regarding the composite reinforcement layer and polymer P2j Polymer P2j is a semi-crystalline polyamide thermoplastic polymer, said semi-crystalline polyamide thermoplastic polymer having the same definition as above.

[0116] There may be one or more composite reinforcing layers.

[0117] Each of said layers consists of a fibrous material in the form of continuous fibers impregnated with a composition comprising mainly at least one thermoplastic polymer P2j, j corresponding to the number of layers present.

[0118] j ranges from 1 to 10, in particular from 1 to 5, especially from 1 to 3, with j=1 being preferred.

[0119] The term "predominantly" means that said at least one polymer is present in an amount of more than 50% by weight, based on the total weight of the composition and matrix of the composite.

[0120] Advantageously, said at least one predominant polymer is present in an amount greater than 60% by weight, in particular greater than 70% by weight, particularly greater than 80% by weight and more particularly greater than or equal to 90% by weight, relative to the total weight of the composition.

[0121] The composition may further comprise impact modifiers and / or additives.

[0122] The additives may be selected from antioxidants, heat stabilizers, UV absorbers, light stabilizers, lubricants, inorganic fillers, flame retardants, plasticizers and pigments.

[0123] In one embodiment, the additives exclude nucleating agents.

[0124] Advantageously, said composition consists mainly of said polyamide thermoplastic polymer P2j, from 0 to 15% by weight of impact modifier, in particular from 0 to 12% by weight of impact modifier, from 0 to 5% by weight of additives, the sum of the constituents of the composition being equal to 100% by weight.

[0125] Advantageously, said composition consists mainly of said polyamide thermoplastic polymer P2j, from 0 to 15% by weight of impact modifier, in particular from 0 to 12% by weight of impact modifier, from 0 to 5% by weight of additives, the sum of the constituents of the composition being equal to 100% by weight.

[0126] Advantageously, said composition consists mainly of said polyamide thermoplastic polymer P2j, from 0 to 15% by weight of impact modifier, in particular from 0 to 12% by weight of impact modifier, from 0 to 5% by weight of additives, the sum of the constituents of the composition being equal to 100% by weight.

[0127] Advantageously, said composition consists mainly of said polyamide thermoplastic polymer P2j, from 0 to 15% by weight of impact modifier, in particular from 0 to 12% by weight of impact modifier, from 0 to 5% by weight of additives, the sum of the constituents of the composition being equal to 100% by weight.

[0128] The at least one predominant polymer in each layer may be the same or different.

[0129] In one embodiment, each reinforcing layer comprises the same type of polyamide.

[0130] Polymer P2j Polyamide thermoplastic polymer P2j "Thermoplastic" or "semi-crystalline polyamide thermoplastic polymer" refers to a material that is generally solid at ambient temperature, softens during temperature increase, in particular after passing its glass transition temperature (Tg), can exhibit true melting above a temperature called the melting point (Tm), and becomes solid again when the temperature falls below its crystallization temperature.

[0131] Tg, Tc and Tm are determined by differential scanning calorimetry (DSC) according to standards 11357-2:2013 and 11357-3:2013, respectively.

[0132] The number average molecular weight Mn of said polyamide thermoplastic polymer P2j preferably ranges from 10,000 to 40,000, preferably from 10,000 to 30,000. These Mn values ​​may correspond to an intrinsic viscosity of 0.8 or greater, determined in m-cresol according to standard ISO 307:2007, but by changing the solvent (m-cresol instead of sulfuric acid, the temperature being 20° C.).

[0133] The nomenclature used to define polyamides is set out in ISO standard 1874-1:2011 "Plastiques - Materiaux polyamides (PA) pour moulage et extrusion - Partie 1: Designation", in particular on page 3 (Tables 1 and 2), and is well known to those skilled in the art.

[0134] The polyamide may be a homopolyamide, or a copolyamide, or a mixture thereof.

[0135] In one embodiment, the thermoplastic polymer is a short-chain semi-crystalline aliphatic polyamide, i.e., a polyamide with an average number of up to 9 carbon atoms per nitrogen atom, or a long-chain aliphatic polyamide, i.e., a polyamide with an average number of more than 9, preferably more than 10, carbon atoms per nitrogen atom.

[0136] In particular, the short-chain aliphatic polyamide is selected from PA6, PA610, PA612, and PA6 / polyolefin mixtures.

[0137] In particular, the long-chain aliphatic polyamide is chosen from polyamide 11 (PA11), polyamide 12 (PA12), polyamide 1010 (PA1010), polyamide 1012 (PA1012), polyamide 1212 (PA1012), or mixtures or copolyamides thereof, in particular PA11 and PA12.

[0138] In one embodiment, the long chain aliphatic polyamide is selected from polyamide 12 (PA12), polyamide 1010 (PA1010), polyamide 1012 (PA1012), polyamide 1212 (PA1012), or mixtures or copolyamides thereof, in particular PA12.

[0139] In another embodiment, the semi-crystalline polyamide thermoplastic polymer is a semi-crystalline, semi-aromatic polyamide, in particular a semi-crystalline, semi-aromatic polyamide having an average number of more than 8, preferably more than 9, carbon atoms per nitrogen atom and a melting temperature of 240°C to less than 280°C.

[0140] Advantageously, the semicrystalline polyamide is a semi-aromatic polyamide, in particular a semi-aromatic polyamide of formula X / YAr as described in EP 1 505 099, in particular a semi-aromatic polyamide of formula A / XT, in which A is selected from units resulting from amino acids, units resulting from lactams, and units corresponding to the formula (Ca diamine).(Cb diacid), a represents the number of carbon atoms in the diamine, b represents the number of carbon atoms in the diacid, a and b each being between 4 and 36, advantageously between 9 and 18, in which the units (Ca diamine) are selected from linear or branched aliphatic diamines, cycloaliphatic diamines and alkylaromatic diamines, and the units (Cb diacid) are selected from linear or branched aliphatic diacids, cycloaliphatic diacids and aromatic diacids.

[0141] XT denotes a unit resulting from the polycondensation of a Cx diamine and terephthalic acid, x representing the number of carbon atoms in the Cx diamine, x being between 5 and 36, advantageously between 9 and 18, and in particular polyamides having the formula A / 5T, A / 6T, A / 9T, A / 10T or A / 11T, A being as defined above, in particular polyamides such as PA MPMDT / 6T, PA11 / 10T, PA 5T / 10T, PA 11 / BACT, PA 11 / 6T / 10T, PA MXDT / 10T, PA MPMDT / 10T, PA BACT / 10T, PA BACT / 6T, PA BACT / 10T / 6T, PA 11 / BACT / 6T, PA 11 / MPMDT / 6T, PA 11 / MPMDT / 10T, PA 11 / BACT / 10T, PA Select from 11 / MXDT / 10T or 11 / 5T / 10T.

[0142] In particular, the semi-aromatic semi-crystalline polyamide is selected from polyamide 11 / 5T or 11 / 6T or 11 / 10T, MXDT / 10T, MPMDT / 10T and BACT / 10T.

[0143] T corresponds to terephthalic acid, MXD corresponds to m-xylylenediamine, MPMD corresponds to methylpentamethylenediamine and BAC corresponds to bis(aminomethyl)cyclohexane. The semi-aromatic polyamides defined above have in particular a Tg of greater than or equal to 80° C.

[0144] Regarding the structure The multi-layer structure thus comprises at least one sealing layer and at least one composite reinforcing layer, the innermost reinforcing layer being welded to the outermost sealing layer and thus adhered to each other.

[0145] All sealing layers present are adhered to one another and all reinforcing layers present are adhered to one another.

[0146] In one embodiment, the Tm of the polyamide of said outermost adjacent sealing layer (1) differs by at most 30° C. from the Tm of the polyamide of said innermost reinforcing layer (2), measured according to ISO 11357-3:2013.

[0147] In another embodiment, the Tg of the polyamide of said outermost adjacent sealing layer (1) differs from the Tg of the polyamide of said innermost reinforcing layer (2) by at most 30° C., measured according to ISO 11357-2:2013.

[0148] Advantageously, the Tm and Tg of the polyamide of said outermost adjacent sealing layer (1) differ by at most 30° C. from the Tm and Tg of the polyamide of said innermost reinforcing layer (2).

[0149] In one embodiment, each sealing layer comprises the same type of polyamide and each reinforcing layer comprises the same type of polyamide.

[0150] The multi-layer structure may include up to 10 sealing layers and up to 10 composite reinforcing layers of different nature.

[0151] It will be apparent that the multi-layer structure is not necessarily symmetrical and may therefore include more sealing layers than composite layers or vice versa, but there may not be alternating layers and reinforcing layers.

[0152] Advantageously, said multilayer structure comprises 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 sealing layers and 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 composite reinforcing layers.

[0153] Advantageously, said multi-layer structure comprises 1, 2, 3, 4 or 5 sealing layers and 1, 2, 3, 4 or 5 composite reinforcing layers.

[0154] Advantageously, said multi-layer structure comprises one, two or three sealing layers and one, two or three composite reinforcing layers.

[0155] In one embodiment, the multi-layer structure comprises a single sealing layer and several reinforcing layers, the reinforcing layers adjacent to a sealing layer being welded to the sealing layer, and other reinforcing layers being wrapped around the directly adjacent reinforcing layers.

[0156] In another embodiment, the multi-layer structure comprises a single reinforcing layer and several sealing layers, the reinforcing layers being welded to the adjacent sealing layers.

[0157] In one advantageous embodiment, the multi-layer structure comprises a single sealing layer and a single composite reinforcing layer, the reinforcing layer being welded to the sealing layer.

[0158] Advantageously, in said multilayer structure, each sealing layer consists of a composition comprising the same type of polyamide polymer P1i.

[0159] Advantageously, the polyamide P1i is the same in all sealing layers.

[0160] Advantageously, said polymer P1i is a short-chain aliphatic polyamide, in particular chosen from PA6, PA610, PA612 and PA6 / polyolefin mixtures, or a long-chain one, in particular chosen from PA1010, PA1012, PA1212, PA11 and PA12, in particular PA11 and PA12, or a semi-aromatic polyamide, in particular chosen from polyamides 11 / 5T, 11 / 6T, 11 / 10T, MXDT / 10T, MPMDT / 10T and BACT / 10T.

[0161] Advantageously, in said multilayer structure, each reinforcing layer consists of a composition comprising the same type of polyamide polymer P2j.

[0162] Advantageously, the polyamide P2j is the same in all reinforcing layers.

[0163] Advantageously, said polymer P2j is a short-chain aliphatic polyamide, in particular chosen from PA6, PA610, PA612, or a long-chain one, in particular chosen from PA1010, PA1012, PA1212, PA11 and PA12, in particular chosen from PA11 and PA12, or a semi-aromatic polyamide, in particular chosen from polyamides 11 / 5T, 11 / 6T, 11 / 10T, MXDT / 10T, MPMDT / 10T and BACT / 10T.

[0164] Advantageously, in said multilayer structure, each sealing layer consists of a composition comprising the same type of polyamide polymer P1i and each reinforcing layer consists of a composition comprising the same type of polyamide polymer P2j.

[0165] Advantageously, said polymer P1i is a short-chain aliphatic polyamide, in particular chosen from PA6, PA610, PA612 and PA6 / polyolefin mixtures, or a long-chain one, in particular chosen from PA1010, PA1012, PA1212, PA11 and PA12, in particular chosen from PA11 and PA12, or a semi-aromatic polyamide, in particular chosen from polyamides 11 / 5T, 11 / 6T, 11 / 10T, MXDT / 10T, MPMDT / 10T and BACT / 10T. The polymer P2j is a short-chain aliphatic polyamide, in particular a short-chain aliphatic polyamide selected from PA6, PA610, PA612, or a long-chain one, in particular selected from PA1010, PA1012, PA1212, PA11 and PA12, in particular PA11 and PA12, or a semi-polyamide-aromatic, in particular selected from polyamide 11 / 5T, 11 / 6T, 11 / 10T, MXDT / 10T, MPMDT / 10T and BACT / 10T.

[0166] In one embodiment, the multilayer structure consists of a single reinforcing layer and a single sealing layer, and the polymer P1i is a short-chain aliphatic polyamide, in particular a short-chain aliphatic polyamide selected from PA6, PA610, PA612 and PA6 / polyolefin, or a long-chain mixture, in particular a long-chain mixture selected from PA1010, PA1012, PA1212, PA11 and PA12, in particular a long-chain mixture selected from PA11 and PA12, or a semi-aromatic polyamide, in particular polyamide 11 / 5T, 11 / 6T, 11 / 10T, MXDT / 10T, MPMDT / 10T and and BACT / 10T, said polymer P2j being a short-chain aliphatic polyamide, in particular selected from PA6, PA610, PA612, or a long-chain, in particular selected from PA1010, PA1012, PA1212, PA11 and PA12, in particular PA11 and PA12, or a semi-aromatic polyamide, in particular selected from polyamides 11 / 5T, 11 / 6T, 11 / 10T, MXDT / 10T, MPMDT / 10T and BACT / 10T.

[0167] In one embodiment, the multilayer structure consists of a single reinforcing layer and a single sealing layer, wherein the polymer P1i is a short-chain aliphatic polyamide, in particular a short-chain aliphatic polyamide selected from PA6, PA610, PA612 and PA6 / polyolefin blends, and the polymer P2j is a short-chain aliphatic polyamide, in particular a short-chain aliphatic polyamide selected from PA6, PA610, PA612.

[0168] In one embodiment, the multilayer structure consists of a single reinforcing layer and a single sealing layer, wherein the polymer P1i is a short-chain aliphatic polyamide, in particular a short-chain aliphatic polyamide selected from PA6, PA610, PA612 and PA6 / polyolefin blends, and the polymer P2j is a long-chain aliphatic polyamide, in particular a long-chain aliphatic polyamide selected from PA1010, PA1012, PA1212, PA11 and PA12, in particular PA11 and PA12.

[0169] In one embodiment, the multilayer structure consists of a single reinforcing layer and a single sealing layer, wherein the polymer P1i is a short-chain aliphatic polyamide, in particular a short-chain aliphatic polyamide selected from PA6, PA610, PA612 and PA6 / polyolefin blends, and the polymer P2j is a semi-aromatic polyamide, in particular a semi-aromatic polyamide selected from polyamides 11 / 5T, 11 / 6T, 11 / 10T, MXDT / 10T, MPMDT / 10T and BACT / 10T.

[0170] In one embodiment, the multilayer structure consists of a single reinforcing layer and a single sealing layer, wherein the polymer P1i is a long-chain aliphatic polyamide, in particular a long-chain aliphatic polyamide selected from PA1010, PA1012, PA1212, PA11 and PA12, in particular PA11 and PA12, and the polymer P2j is a short-chain aliphatic polyamide, in particular a short-chain aliphatic polyamide selected from PA6, PA610, PA612.

[0171] In one embodiment, the multilayer structure consists of a single reinforcing layer and a single sealing layer, wherein the polymer P1i is a long-chain aliphatic polyamide, in particular a long-chain aliphatic polyamide selected from PA1010, PA1012, PA1212, PA11 and PA12, in particular PA11 and PA12, and wherein the polymer P2j is a long-chain aliphatic polyamide, in particular a long-chain aliphatic polyamide selected from PA1010, PA1012, PA1212, PA11 and PA12, in particular PA11 and PA12.

[0172] In one embodiment, the multilayer structure consists of a single reinforcing layer and a single sealing layer, wherein the polymer P1i is a long-chain aliphatic polyamide, in particular a long-chain aliphatic polyamide selected from PA1010, PA1012, PA1212, PA11 and PA12, in particular PA11 and PA12, and wherein the polymer P2j is a semi-aromatic polyamide, in particular a semi-aromatic polyamide selected from polyamide 11 / 5T, 11 / 6T, 11 / 10T, MXDT / 10T, MPMDT / 10T and BACT / 10T.

[0173] In one embodiment, the multilayer structure consists of a single reinforcing layer and a single sealing layer, wherein the polymer P1i is a semi-aromatic polyamide, in particular a semi-aromatic polyamide selected from polyamides 11 / 5T, 11 / 6T, 11 / 10T, MXDT / 10T, MPMDT / 10T and BACT / 10T, and the polymer P2j is a short-chain aliphatic polyamide, in particular a short-chain aliphatic polyamide selected from PA6, PA610, PA612.

[0174] In one embodiment, the multilayer structure consists of a single reinforcing layer and a single sealing layer, wherein the polymer P1i is a semi-aromatic polyamide, in particular a semi-aromatic polyamide selected from polyamides 11 / 5T, 11 / 6T, 11 / 10T, MXDT / 10T, MPMDT / 10T and BACT / 10T, and the polymer P2j is a long-chain aliphatic polyamide, in particular a long-chain aliphatic polyamide selected from PA1010, PA1012, PA1212, PA11 and PA12, in particular PA11 and PA12.

[0175] In one embodiment, the multilayer structure consists of a single reinforcing layer and a single sealing layer, wherein the polymer P1i is a semi-aromatic polyamide, in particular a semi-aromatic polyamide selected from polyamides 11 / 5T, 11 / 6T, 11 / 10T, MXDT / 10T, MPMDT / 10T and BACT / 10T, and the polymer P2j is a semi-aromatic polyamide, in particular a semi-aromatic polyamide selected from polyamides 11 / 5T, 11 / 6T, 11 / 10T, MXDT / 10T, MPMDT / 10T and BACT / 10T.

[0176] Advantageously, said multilayer structure further comprises at least one outer layer of fibrous material made of continuous glass fibers impregnated with a transparent amorphous polymer, said layer being the outermost layer of said multilayer structure.

[0177] The outer layer is a second, reinforcing layer but is permeable, allowing text to be placed on the structure.

[0178] Regarding fibrous materials As regards the fibres that make up said fibrous material, these are in particular inorganic, organic or vegetable fibres.

[0179] Advantageously, said fibrous material may be sized or unsized.

[0180] The fibrous material may therefore contain up to 3.5% by weight of organic material (of the thermoset or thermoplastic type) called sizing.

[0181] Inorganic fibers include, for example, carbon fibers, glass fibers, basalt or basalt-based fibers, silica fibers, or silicon carbide fibers. Organic fibers include thermoplastic or thermosetting polymer-based fibers, such as semi-aromatic polyamide fibers, aramid fibers, or polyolefin fibers. Preferably, they are based on amorphous thermoplastic polymers, with a glass transition temperature (Tg) higher than the glass transition temperature (Tg) of the polymer or thermoplastic polymer mixture that constitutes the pre-impregnated matrix if the thermoplastic polymer mixture is amorphous, or higher than the glass transition temperature (Tm) of the polymer or thermoplastic polymer mixture that constitutes the pre-impregnated matrix if the thermoplastic polymer mixture is semi-crystalline. Advantageously, they are based on semi-crystalline thermoplastic polymers, with a melting temperature (Tm) higher than the glass transition temperature (Tg) of the polymer or thermoplastic polymer mixture that constitutes the pre-impregnated matrix if the thermoplastic polymer mixture is amorphous, or higher than the glass transition temperature (Tm) of the polymer or thermoplastic polymer mixture that constitutes the pre-impregnated matrix if the thermoplastic polymer mixture is semi-crystalline. Therefore, there is no risk of the organic fibers that constitute the fibrous material melting during impregnation with the thermoplastic matrix of the final composite. Plant fibers include natural linen, hemp, lignin, bamboo, silk, particularly spider silk, sisal, and other cellulosic fibers, particularly viscose. These plant fibers can be used alone or can be treated or coated with a coating layer to promote adhesion and impregnation of the thermoplastic polymer matrix.

[0182] The fibrous material can also be a woven fabric using cloth, string or fibers.

[0183] This may also correspond to a fiber with supporting threads.

[0184] These component fibers can be used alone or in mixtures. Thus, organic fibers can be mixed with inorganic fibers and pre-impregnated with a thermoplastic polymer powder to form a pre-impregnated fibrous material.

[0185] The strands of organic fibers may have several basis weights. They may also have several shapes. The component fibers of the fibrous material may also take the form of a mixture of these reinforcing fibers having different shapes. The fibers are continuous fibers.

[0186] Preferably, the fibrous material is selected from glass fibers, carbon fibers, basalt fibers or basalt-based fibers, or mixtures thereof, in particular carbon fibers.

[0187] It is used in the form of one roving or several rovings.

[0188] According to another aspect, the invention relates to a method for manufacturing a multilayer structure as defined above, characterized in that it comprises a step of filament winding a reinforcing layer as defined above around a sealing layer as defined above.

[0189] All the properties detailed above also apply to the method. [Example]

[0190] In all cases, the tank is obtained by rotational moulding of a sealing layer (liner) at a temperature adapted to the properties of the thermoplastic resin used.

[0191] For the composite reinforcement, a fibrous material (tape) previously impregnated with a thermoplastic resin is used, which is deposited by filament winding using a robot with a 1500W laser heater at a speed of 12 m / min, without a polymerization step.

[0192] Example 1 (counterexample): Type IV hydrogen storage tank, consisting of epoxy composite reinforcement (Tg100℃) T700SC31E carbon fiber (manufactured by Toray) and PA11 sealing layer.

[0193] Example 2: Type IV hydrogen storage tank constructed of T700SC31E carbon fiber PA11 composite reinforcement (manufactured by Toray) and a PA11 sealing layer.

[0194] The resulting tank is subjected to a cyclic pressure test varying between 10 and 800 bar. Water is used to apply the pressure. The test is stopped after 10,000 cycles.

[0195] Following this, strips of approximately 1 cm width are cut from the tank. Removal is then initiated at the interface and a peel test is carried out using a traction machine to measure the adhesion between the liner and the composite. The peel strength is expressed in N / cm strip width. In the case of Example 1, removal is observed at a value of 3 N / cm. In the case of Example 2, forces of more than 30 N / cm are reached.

Claims

1. A multi-layer structure configured to transport, distribute and store hydrogen, comprising: From the inside to the outside, it comprises at least one sealing layer (1) and at least one composite reinforcing layer (2), an innermost composite reinforcing layer (2) welded to an adjacent outermost sealing layer (1); The sealing layer (1) is made of a composition, the composition comprising: at least 50% by weight of at least one semi-crystalline polyamide thermoplastic polymer P1i, i=1 to n, n being the number of sealing layers, up to 50% by weight, based on the total weight of the composition, of an impact modifier; Up to 1.5% by weight of a plasticizer, based on the total weight of the composition Including, The composition in each sealing layer excludes polyether block amide (PEBA); the at least one polyamide thermoplastic polymer in each sealing layer may be the same or different; at least one of said composite reinforcing layers consists of a fibrous material in the form of continuous fibers impregnated with a composition comprising at least 50% by weight of at least one semicrystalline polyamide polymer P2j, j=1 to m, m being the number of reinforcing layers; the number of carbon atoms per amide functional group of the polyamide of the outermost adjacent sealing layer (1) differs by up to 20% from the number of carbon atoms per amide functional group of the polyamide of the innermost reinforcing layer (2); the structure further comprises at least one outer layer of a fibrous material made of continuous glass fibers impregnated with a transparent amorphous polymer, said layer being the outermost layer of the multi-layer structure; Multilayer structure.

2. 2. The multilayer structure according to claim 1, characterized in that the Tm of the polyamide of the outermost adjacent sealing layer (1) differs by a maximum of 30° C. from the Tm of the polyamide of the innermost reinforcing layer (2), measured according to ISO 11357-3:2013.

3. 2. The multilayer structure according to claim 1, characterized in that the Tg of the polyamide of the outermost adjacent sealing layer (1) differs by a maximum of 30° C. from the Tg of the polyamide of the innermost reinforcing layer (2), measured according to ISO 11357-2:2013.

4. 4. A multilayer structure according to claim 2 or 3, characterized in that the Tm and Tg of the polyamide of the outermost adjacent sealing layer (1) differs by up to 30° C. from the Tm and Tg of the polyamide of the innermost reinforcing layer (2).

5. 5. A multi-layer structure according to claim 1, wherein each sealing layer comprises the same polyamide.

6. 5. A multilayer structure according to claim 1, wherein each reinforcing layer comprises the same polyamide.

7. 7. A multi-layer structure according to claim 5 or 6, characterized in that each sealing layer comprises the same polyamide and each reinforcing layer comprises the same polyamide.

8. 5. A multi-layer structure according to any one of claims 1 to 4, characterized in that it has a single sealing layer and a single reinforcing layer.

9. 9. A multilayer structure according to claim 1 , characterized in that the polymer P1i is a short-chain aliphatic polyamide with an average number of up to 9 carbon atoms per nitrogen atom, or a long-chain aliphatic polyamide with an average number of more than 9 carbon atoms per nitrogen atom, or a semi-aromatic polyamide.

10. 9. A multilayer structure according to claim 1 , characterized in that the polymer P2j is a short-chain aliphatic polyamide with an average number of up to 9 carbon atoms per nitrogen atom, or a long-chain aliphatic polyamide with an average number of more than 9 carbon atoms per nitrogen atom, or a semi-aromatic polyamide.

11. 11. Multilayer structure according to claim 9 or 10, characterized in that the polymer P1i is a short-chain aliphatic polyamide with an average number of up to 9 carbon atoms per nitrogen atom, or a long-chain aliphatic polyamide with an average number of more than 9 carbon atoms per nitrogen atom, or a semi-aromatic polyamide, and the polymer P2j is a short-chain aliphatic polyamide with an average number of up to 9 carbon atoms per nitrogen atom, or a long-chain aliphatic polyamide with a number average number of more than 9 carbon atoms per nitrogen atom, or a semi-aromatic polyamide.

12. 12. A multilayer structure according to any one of claims 1 to 11, characterized in that the fibrous material of the composite reinforcing layer is selected from glass fibres, carbon fibres, basalt fibres or basalt-based fibres, or mixtures thereof.

13. 13. A method for manufacturing a multi-layer structure according to any one of claims 1 to 12, characterized in that it comprises the step of welding a reinforcing layer according to claim 1 to a sealing layer according to claim 1.