EP4096922A1

EP4096922A1 - Multilayer structure for transporting or storing hydrogen

Info

Publication number: EP4096922A1
Application number: EP21708054.8A
Authority: EP
Inventors: Nicolas Dufaure; Patrick Dang; Antoine GOUPIL
Original assignee: Arkema France SA
Current assignee: Arkema France SA
Priority date: 2020-01-28
Filing date: 2021-01-26
Publication date: 2022-12-07
Also published as: CN115023344A; WO2021152253A1; US20230075842A1; FR3106646A1; CA3163652A1; FR3106646B1; JP2023511976A; MX2022008891A; KR20220133959A

Abstract

Multilayer structure for transporting, distributing and storing hydrogen, comprising, from the inside to the outside, at least one sealing layer (1) and at least one composite reinforcing layer (2), the innermost composite reinforcing layer being wound around the outermost adjacent sealing layer (1), the sealing layers consisting of a composition predominantly comprising at least one semi-crystalline, long-chain polyamide thermoplastic polymer P1i (i = 1 to n, n being the number of sealing layers), the Tf of which, as measured according to ISO 11357-3: 2013, is greater than 160°C, with the exception of one polyether block amide (PEBA), up to 50% by weight of impact modifier relative to the total weight of the composition and up to 1.5% by weight of plasticiser relative to the total weight of the composition, the composition being free of nucleating agent, the at least one polyamide thermoplastic polymer of each sealing layer being able to be identical or different, and at least one of the composite reinforcing layers consisting of a fibrous material in the form of continuous fibres impregnated by a composition predominantly comprising at least one polymer P2j (j = 1 to m, m being the number of reinforcing layers), in particular an epoxy resin or epoxy-based resin, and the structure being free of an outermost layer adjacent to the outermost polyamide polymer composite reinforcing layer.

Description

DESCRIPTION

TITLE: MULTI-LAYER STRUCTURE FOR THE TRANSPORT OR STORAGE OF

HYDROGEN

[Technical area]

The present patent application relates to composite multilayer structures for the transport, distribution or storage of hydrogen, in particular for the distribution or storage of hydrogen, and their manufacturing process.

[Prior art]

Hydrogen tanks are a subject that is currently attracting a lot of interest from many manufacturers, especially in the automotive field. One of the goals is to offer vehicles that pollute less and less. Thus, electric or hybrid vehicles comprising a battery aim to gradually replace thermal vehicles, such as gasoline or diesel vehicles. However, it turns out that the battery is a relatively complex component of the vehicle. Depending on the location of the battery in the vehicle, it may be necessary to protect it from impact and the external environment, which can be extreme temperatures and varying humidity. It is also necessary to avoid any risk of flames.

In addition, it is important that its operating temperature does not exceed 55 ° C so as not to damage the battery cells and preserve its lifespan. Conversely, for example in winter, it may be necessary to raise the temperature of the battery in order to optimize its operation.

In addition, the electric vehicle still suffers today from several problems, namely the autonomy of the battery, the use in these rare earth batteries whose resources are not inexhaustible, recharging times much longer than the durations. tank filling, as well as a problem of electricity production in the different countries to be able to recharge the batteries.

Hydrogen therefore represents an alternative to the electric battery since hydrogen can be transformed into electricity by means of a fuel cell and thus power electric vehicles.

Hydrogen tanks generally consist of a metal casing (liner or sealing layer) which must prevent the permeation of hydrogen. One of the types of tanks being considered, called Type IV, is based on a thermoplastic liner around which a composite is wrapped.

Their basic principle is to separate the two essential functions of sealing and mechanical strength in order to manage them one independently of the other. In this type of tank, a thermoplastic resin liner (or sealing sheath) is combined with a reinforcing structure made up of fibers (glass, aramid, carbon). called sheath or reinforcing layer which allow to work at much higher pressures while reducing the mass and avoiding the risk of explosive rupture in the event of severe external attacks.

Liners should have some basic characteristics:

The possibility of being transformed by extrusion blow molding, rotational molding, injection, or extrusion

Low hydrogen permeability, the permeability of the liner is indeed a key factor in limiting hydrogen losses from the tank;

Good mechanical properties (fatigue) at low temperatures (-40 to -70 ° C);

Thermal resistance at 120 ° C.

Indeed, it is necessary to increase the filling speed of the hydrogen tank which must be approximately equivalent to that of a gasoline tank for a heat engine (approximately 3 to 5 minutes) but this increase in speed causes the heating of the fuel tank. larger tank which then reaches a temperature of around 100 ° C.

The evaluation of the performance and safety of hydrogen tanks can be determined in a European reference laboratory (GasTeF: hydrogen tank test facility) as described in Galassi et al. (Word hydrogen energy conference 2012, Onboard compressed hydrogen storage: fast filing experiments and simulations, Energy Procedia 29, (2012) 192-200).

The first generation of type IV tanks used a liner based on high density polyethylene (HDPE).

However, HDPE has the drawback of having too low a melting temperature and high hydrogen permeability, which is a problem with the new thermal withstand requirements and does not allow the filling speed of the tank to be increased. tank.

For several years, liners based on polyamide PA6 have been developed. However, PA6 has the disadvantage of having poor cold resistance.

Application EP3112421 describes a polyamide resin composition for a molded article intended for high pressure hydrogen, the composition comprising: a polyamide 6 resin (A); and a polyamide resin (B) having a melting point, as determined by DSC, which is not higher than the melting point of the polyamide 6 resin (A) + 20 ° C and a cooling crystallization temperature, such as determined by DSC, which is higher than the cooling crystallization temperature of the polyamide 6 resin (A).

French application FR2923575 describes a reservoir for storing fluid under high pressure comprising at each of its ends along its axis a nozzle metal end, a liner enveloping said end caps and a structural layer of fiber impregnated with thermosetting resin enveloping said liner.

Application EP3222668 describes a polyamide resin composition for a molded article intended for high pressure hydrogen, the composition comprising a polyamide resin (A) comprising a unit derived from hexamethylenediamine and a unit derived from an aliphatic dicarboxylic acid of 8 to 12 carbon atoms and an ethylene / α-olefin copolymer (B) modified with an unsaturated carboxylic acid and / or a derivative thereof.

Application US2014 / 008373 describes a lightweight storage cylinder for a high pressure compressed gas, the cylinder having a liner wrapped in a stress layer, the liner comprising: a first inner layer of impact modified polyamide (PA) in contact with gas, an outer thermoplastic layer in contact with the stress layer; and an adhesive tie layer between the first impact modified inner PA layer and the outer thermoplastic layer.

WO1 8155491 describes a hydrogen transport component having a three-layer structure, the inner layer of which is a composition consisting of PA11, 15 to 50% of an impact modifier and 1 to 3% of plasticizer or without plasticizer which exhibits hydrogen barrier properties, good flexibility and durability at low temperature. However, this structure is suitable for pipes for transporting hydrogen but not for storing hydrogen.

Thus, it remains to optimize on the one hand, the matrix of the composite in order to optimize its mechanical resistance at high temperature and on the other hand the material composing the sealing sheath, in order to optimize its processing temperature. Thus, the possible modification of the composition of the material composing the sealing sheath, which will be made, must not result in a significant increase in the manufacturing temperature (extrusion-blow molding, injection, rotomoulding, etc.) of this liner, compared to what is practiced today.

These problems are solved by providing a multilayer structure of the present invention intended for the transport, distribution or storage of hydrogen. Throughout this description, the terms "liner" and "sealing sheath" have the same. meaning.

The present invention therefore relates to a multilayer structure, intended for the transport, distribution or storage of hydrogen, comprising, from the inside to the outside, at least one sealing layer (1) and at least one layer. of composite reinforcement (2), said innermost composite reinforcement layer being wrapped around said outermost adjacent sealing layer (1), said sealing layer (s) consisting of a composition mainly comprising: at least one thermoplastic polyamide polymer P1i, i = 1 to n, n being the number of sealing layers, semi-crystalline, of which the Tf, as measured according to ISO 11357-3: 2013, is greater than 160 ° C, in particular greater than 170 ° C, excluding a polyether block amide (PEBA), up to 50% by weight of impact modifier, in particular up to 'less than 15% by weight of impact modifier, in particular up to 12% by weight of impact modifier relative to the total weight of the composition, up to 1.5% by weight of plasticizer relative to the total weight of the composition, said composition being devoid of nucleating agent, said at least one thermoplastic polyamide polymer of each sealing layer possibly being the same or different, and at least one of said composite reinforcing layers being made of a fibrous material in the form of continuous fibers impregnated with a compound composition mainly comprising at least one polymer P2j, j = 1 to m, m being the number of reinforcing layers, in particular an epoxy resin or epoxy-based, said structure being devoid of an outermost layer and adjacent to the outermost layer of composite reinforcement in polyamide polymer.

The inventors have therefore unexpectedly found that the use of a thermoplastic polyamide polymer with a long semi-crystalline chain, comprising a proportion of impact modifier and of limited plasticizer, for the sealing layer, with a different polymer for the matrix. composite and in particular an epoxy resin or epoxy-based, said composite being wound on the waterproofing layer, made it possible to obtain a structure suitable for the transport, distribution or storage of hydrogen and in particular a increase in the maximum temperature of use up to 120 ° C, thus making it possible to increase the speed of filling the tanks.

By "multilayer structure" is meant a tank comprising or consisting of several layers, namely several sealing layers and several reinforcing layers, or one sealing layer and several reinforcing layers, or several sealing layers and a backing layer or a waterproofing layer and a backing layer.

The multilayer structure is therefore meant to the exclusion of a pipe or tube.

Poly ether block amide (PEBA) are copolymers with amide units (Ba1) and polyether units (Ba2), said amide unit (Ba1) corresponding to an aliphatic repeating unit chosen from a unit obtained from at least one amino acid or a unit obtained from at least one lactam, or an XY unit obtained from polycondensation: - at least one diamine, said diamine being preferably chosen from a linear or branched aliphatic diamine or a mixture thereof, and

- at least one dicarboxylic acid, said dicarboxylic acid being preferably chosen from: a linear or branched aliphatic dicacid, or a mixture of these, said diamine and said dicacid comprising from 4 to 36 carbon atoms, advantageously from 6 to 18 carbon atoms; said polyether units (Ba2) being in particular derived from at least one polyalkylene ether polyol, in particular a polyalkylene ether diol.

Nucleating agents are known to those skilled in the art and refer to a substance which, when incorporated into a polymer, forms nuclei for crystal growth in the molten polymer.

They can be chosen, for example, from micro talc, carbon black, silica, titanium dioxide and nanoclays.

In one embodiment, PA6 and PA610 are excluded from said composition. The expression "said structure being devoid of an outermost layer and adjacent to the outermost layer of composite reinforcement of polyamide polymer" means that the structure is devoid of a layer of polyamide polymer situated above the layer. outermost composite reinforcement.

In one embodiment, said multilayer structure consists of two layers, a waterproofing layer and a reinforcing layer.

The waterproofing layer or layers are the innermost layers compared to the composite reinforcing layers which are the outermost layers.

The tank can be a tank for the mobile storage of hydrogen, i.e. on a truck for the transport of hydrogen, on a car for the transport of hydrogen and the supply of hydrogen d '' a fuel cell for example, on a train for the supply of hydrogen or on a drone for the supply of hydrogen, but it can also be a stationary storage tank for hydrogen in a station for the distribution of hydrogen to vehicles.

Advantageously, the sealing layer (1) is impermeable to hydrogen at 23 ° C, that is to say that the permeability to hydrogen at 23 ° C is less than 500 cc.mm/m2. 24h. .atm at 23 ° C under 0% relative humidity (RH).

In one embodiment, said sealing layer (s) consist of a composition comprising mainly: at least one thermoplastic polyamide PU polymer, i = 1 to n, n being the number of sealing layers, semi-crystalline of which the Tm, as measured according to ISO 11357-3: 2013, is greater than 160 ° C, in particular greater than 170 ° C, excluding a polyether block amide (PEBA), and excluding PA11 . The composite reinforcing layer (s) is (are) wound (s) around the sealing layer by means of tapes (or tapes or rovings) of fibers impregnated with polymer which are deposited, for example, by filament winding.

When multiple layers are present, the polymers are different.

When the polymers of the reinforcing layers are identical, there may be several layers present, but advantageously, only one reinforcing layer is present and which then has at least one complete winding around the waterproofing layer.

This fully automated process, well known to those skilled in the art, makes it possible, layer by layer, to choose the winding angles which will give the final structure its ability to withstand internal pressure loading.

When multiple waterproofing layers are present, only the innermost layer of the waterproofing layers is in direct contact with hydrogen.

When only a waterproofing layer and a composite reinforcing layer are present, thus leading to a multilayer structure with two layers, then these two layers can adhere to each other, in direct contact with each other , in particular due to the winding of the composite reinforcing layer on the waterproofing layer. When several waterproofing layers are present and / or several composite reinforcing layers, then the outermost layer of said waterproofing layers, and therefore opposite the layer in contact with hydrogen, may or may not adhere to the innermost layer of said composite reinforcement.

The other composite reinforcement layers may or may not also adhere to each other. The other waterproofing layers may or may not adhere to each other. Advantageously, only a waterproofing layer and a reinforcing layer are present and do not adhere to each other.

Advantageously, only a sealing layer and a reinforcing layer are present and do not adhere to each other and the reinforcing layer consists of a fibrous material in the form of continuous fibers impregnated with a composition mainly comprising at least one polymer P2j , in particular an epoxy resin or based on epoxy.

In one embodiment, only a waterproofing layer and a reinforcing layer are present and do not adhere to each other and the reinforcing layer consists of a fibrous material in the form of continuous fibers impregnated with a composition mainly comprising a P2j polymer which is an epoxy or epoxy-based resin.

The term epoxy-based throughout the description means that the epoxy represents at least 50% by weight of the matrix.

Regarding the sealing layer (s) and the thermoplastic polymer P1i One or more sealing layers may or may be present.

Each of said layers consists of a composition mainly comprising at least one thermoplastic polymer P1i, i corresponding to the number of layers present i is from 1 to 10, in particular from 1 to 5, in particular from 1 to 3, preferably i = 1 .

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.

Advantageously, said at least one majority polymer is present at more than 60% by weight, in particular at more than 70% by weight, particularly at more than 80% by weight, more particularly greater than or equal to 90% by weight 90% by weight, relative to the total weight of the composition.

Said composition can also comprise up to 50% by weight relative to the total weight of the composition of impact modifiers and / or a plasticizer and / or additives.

The additives can 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 colorant, carbon black and carbonaceous nanofillers, with the exception of a nucleating agent, in particular the additives are chosen from an antioxidant, a heat stabilizer, a UV absorber, a light stabilizer, a lubricant, an inorganic filler, a flame retardant, a colorant, carbon black and carbonaceous nanofillers, except for a nucleating agent.

Said other polymer can be another semi-crystalline thermoplastic polymer or a different polymer and in particular an EVOH (Ethylene vinyl alcohol).

Advantageously, said composition comprises said thermoplastic polymer P1i predominantly, 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% plasticizer and 0 to 5% by weight of additives, the sum of the constituents of the composition being equal to 100%.

Advantageously, said composition consists of said thermoplastic polymer P1i predominantly, 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% plasticizer and 0 to 5% by weight of additives, the sum of the constituents of the composition being equal to 100%.

Said at least one majority polymer of each layer may be identical or different. In one embodiment, a single major polymer is present at least in the sealing layer which does not adhere to the composite reinforcing layer. In one embodiment, said composition comprises an impact modifier of 0.1 to 50% by weight, in particular from 0.1 to less than 15% by weight, in particular from 0.1 to 12% by weight of impact modifier by relative to the total weight of the composition.

In one embodiment, said composition is devoid of plasticizer.

In another embodiment, said composition comprises an impact modifier of 0.1 to 50% by weight, in particular from 0.1 to less than 15% by weight, in particular from 0.1 to 12% by weight of impact modifier and said composition is devoid of plasticizer relative to the total weight of the composition.

In yet another embodiment, said composition comprises an impact modifier of 0.1 to 50% by weight, in particular from 0.1 to less than 15% by weight, in particular from 0.1 to 12% by weight of modifier. impact and from 0.1 to 1.5% by weight of plasticizer relative to the total weight of the composition.

In another embodiment, said composition is devoid of impact modifier. Advantageously, said composition comprises from 0.1 to 1.5% by weight of plasticizer relative to the total weight of the composition and said composition is devoid of impact modifier.

In yet another embodiment, said composition is devoid of impact modifier and plasticizer.

In this last embodiment, said composition comprises said thermoplastic polymer P1i predominantly and from 0 to 5% by weight of additives, in particular from 0.1 to 5% of additives, the sum of the constituents of the composition being equal to 100%.

In this case, said majority thermoplastic polymer P1i is mixed with another polyamide.

Advantageously, said composition comprises said thermoplastic polymer P1i and from 0 to 5% by weight of additives, in particular from 0.1 to 5% of additives, the sum of the constituents of the composition being equal to 100%.

Advantageously, said composition consists of said thermoplastic polymer P1i predominantly and from 0 to 5% by weight of additives, in particular from 0.1 to 5% of additives, the sum of the constituents of the composition being equal to 100%.

Advantageously, said composition consists of said thermoplastic polymer P1i and from 0 to 5% by weight of additives, in particular from 0.1 to 5% of additives, the sum of the constituents of the composition being equal to 100%.

Thermoplastic polymer P1i

The term thermoplastic, or semi-crystalline thermoplastic polymer, is understood to mean a material which is generally solid at room temperature, and which softens during an increase. temperature, in particular after passing through its glass transition temperature (Tg), and which may present a clear melting when passing its so-called melting temperature (Tf), and which becomes solid again when the temperature drops below its crystallization temperature.

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

The number-average molecular mass Mn of said semi-crystalline polyamide thermoplastic polymer is preferably in a range from 10,000 to 85,000, in particular from 10,000 to 60,000, preferably from 10,000 to 50,000, even more preferably from 12,000 to 50,000. These Mn values may correspond to inherent viscosities greater than or equal to 0.8 as determined in m-cresol according to ISO 307: 2007 but by changing the solvent (use of m-cresol instead of sulfuric acid and the temperature being 20 ° C).

The nomenclature used to define polyamides is described in standard ISO 1874-1: 2011 "Plastics - Polyamide materials (PA) for molding and extrusion - Part 1: Designation", in particular on page 3 (tables 1 and 2) and is indeed known to those skilled in the art.

The polyamide can be a homopolyamide or a copolyamide or a mixture thereof. In one embodiment, said thermoplastic polymer is a long chain aliphatic polyamide, that is to say a polyamide having an average number of carbon atoms per nitrogen atom greater than 8.5, preferably greater than 9, in particular greater than 10.

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 a mixture thereof or a copolyamide thereof, in particular PA11 and PA12.

More particularly, polyamide 11 (PA11), polyamide 12 (PA12), polyamide 1012 (PA1012), polyamide 1212 (PA1012), or a mixture thereof or a copolyamide thereof, in particular PA11 and PA12.

In one embodiment, the long chain aliphatic polyamide is chosen from: polyamide 12 (PA12), polyamide 1010 (PA1010), polyamide 1012 (PA1012), polyamide 1212 (PA1012), or a mixture of these- ci or a copolyamide thereof, in particular PA12.

In another embodiment, the long chain aliphatic polyamide is selected from: polyamide 12 (PA12), polyamide 1012 (PA1012), polyamide 1212 (PA1012), or a mixture of these or a copolyamide of those here, in particular PA12. In another embodiment, said semi-crystalline polyamide thermoplastic polymer is a long-chain semi-crystalline semi-aromatic polyamide, that is to say a polyamide having an average number of carbon atoms per nitrogen atom. greater than 8.5, preferably greater than 9, in particular greater than 10, and a melting temperature of between 240 ° C to less than 280 ° C.

In particular, the long-chain semi-crystalline semi-aromatic polyamide is chosen from polyamide 11 / 5T or 11 / 6T or 11 / 10T, MXDT / 10T, MPMDT / 10T and BACT / 10T.

Advantageously, each waterproofing layer consists of a composition comprising the same type of polyamide.

In the event that soldering is required, there are various methods of soldering elements made of thermoplastic polyamide polymer. Thus, it can be used heated blades with or without contact, ultrasound, infrared, application of vibrations, a rotation of one element to be welded against the other or even laser welding.

Regarding the impact modifier

The impact modifier can be any impact modifier from the moment when a polymer of lower modulus than that of the resin, exhibiting good adhesion with the matrix, so as to dissipate the cracking energy.

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

In one embodiment, PEBAs are excluded from the definition of impact modifiers. The polyolefin of the impact modifier can be functionalized or non-functionalized or be a mixture of at least one functionalized and / or at least one non-functionalized. For simplicity, the polyolefin has been designated by (B) and functionalized polyolefins (B1) and unfunctionalized polyolefins (B2) have been described below.

An unfunctionalized polyolefin (B2) is conventionally a homopolymer or copolymer of alpha olefins or diolefins, such as, for example, ethylene, propylene, butene-1, octene-1, butadiene. By way of example, we can cite:

- polyethylene homopolymers and copolymers, in particular LDPE, HDPE, LLDPE (linear low density polyethylene, or linear low density polyethylene), VLDPE (very low density polyethylene, or very low density polyethylene) and metallocene polyethylene.

the homopolymers or copolymers of propylene. - ethylene / alpha-olefin copolymers such as ethylene / propylene, EPR (abbreviation of 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 with at least one product chosen from salts or esters of unsaturated carboxylic acids such as alkyl (meth) acrylate (for example methyl acrylate), or vinyl esters of carboxylic acids saturated such as vinyl acetate (EVA), the proportion of comonomer being up to 40% by weight. The functionalized polyolefin (B1) can be a polymer of alpha olefins having reactive units (the functionalities); such reactive units are acid, anhydride or epoxy functions. By way of example, mention may be made of the preceding polyolefins (B2) grafted or co- or ter polymerized with unsaturated epoxides such as glycidyl (meth) acrylate, or with carboxylic acids or the corresponding salts or esters such as (meth) acrylic acid (the latter being able to be totally or partially neutralized by metals such as Zn, etc.) or alternatively by carboxylic acid anhydrides such as maleic anhydride. A functionalized polyolefin is for example a PE / EPR mixture, the weight ratio of which can vary widely, for example between 40/60 and 90/10, said mixture being co-grafted with an anhydride, in particular maleic anhydride, according to a degree of grafting, for example from 0.01 to 5% by weight.

The functionalized polyolefin (B1) can be chosen from the following (co) polymers, grafted with maleic anhydride or glycidyl methacrylate, in which the degree of grafting is for example from 0.01 to 5% by weight:

- PE, PP, copolymers of ethylene with propylene, butene, hexene or octene containing, for example, from 35 to 80% by weight of ethylene;

- ethylene / alpha-olefin copolymers such as ethylene / propylene, EPR (abbreviation of ethylene-propylene-rubber) and ethylene / propylene / diene (EPDM).

- ethylene and vinyl acetate (EVA) copolymers, 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;

- copolymers of ethylene and vinyl acetate (EVA) and (meth) acrylate, containing up to 40% by weight of comonomers. The functionalized polyolefin (B1) can also be chosen from ethylene / propylene copolymers predominantly in propylene grafted with maleic anhydride then condensed with mono-amine polyamide (or a polyamide oligomer) (products described in EP-A-0342066) .

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

By way of example of functionalized polyolefins of the latter type, mention may be made of the following copolymers, where ethylene preferably represents at least 60% by weight and where the ter monomer (the function) represents for example from 0.1 to 10% by weight of the copolymer:

- ethylene / (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 (meth) acrylate / (meth) acrylic acid or maleic anhydride or glycidyl methacrylate copolymers.

In the above copolymers, (meth) acrylic acid can be salified with Zn or Li.

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

Furthermore, the aforementioned polyolefins (B1) can also be crosslinked by any suitable process or agent (diepoxy, diacid, peroxide, etc.); the term functionalized polyolefin also includes mixtures of the abovementioned polyolefins with a difunctional reagent such as diacid, dianhydride, diepoxy, and the like. capable of reacting with these or mixtures of at least two functionalized polyolefins capable of reacting with each other.

The copolymers mentioned above, (B1) and (B2), can be copolymerized in a random or block fashion and have a linear or branched structure.

The molecular weight, the MFI number, the density of these polyolefins can also vary to a large extent, which will be appreciated by those skilled in the art. MFI, short for Melt Flow Index, is the melt flow index. It is measured according to standard ASTM 1238. Advantageously, the unfunctionalized polyolefins (B2) are chosen from homopolymers or copolymers of polypropylene and any homopolymer of ethylene or copolymer of ethylene and of a comonomer of higher alpha olefinic type. such as butene, hexene, octene or 4-methyl 1-Pentene. Mention may be made, for example, of PPs, high density PE, medium density PE, linear low density PE, low density PE, very low density PE. These polyethylenes are known to those skilled in the art as being produced according to a “radical” process, according to a “Ziegler” type catalysis or, more recently, according to a so-called “metallocene” catalysis.

Advantageously, the functionalized polyolefins (B1) are chosen from any polymer comprising alpha olefinic units and units bearing polar reactive functions such as epoxy, carboxylic acid or carboxylic acid anhydride functions. As examples of such polymers, mention may be made of the ter polymers of ethylene, of alkyl acrylate and of maleic anhydride or of glycidyl methacrylate, such as Lotader® from the Applicant or polyolefins grafted with l. maleic anhydride such as Orevac® from the Applicant as well as ter polymers of ethylene, of alkyl acrylate and of (meth) acrylic acid. Mention may also be made of homopolymers or copolymers of polypropylene grafted with a carboxylic acid anhydride and then condensed with polyamides or mono-amino polyamide oligomers.

Advantageously, said constituent composition of said sealant layer or layers is devoid of polyether block amide (PEBA). In this embodiment, the PEBAs are therefore excluded from the impact modifiers.

Advantageously, said transparent composition is devoid of core-shell particles or “core-shell” core-shell polymers.

By core-shell particle, it is necessary to understand a particle of which the first layer forms the core and the second or all of the following layers form the respective shell.

The core-shell particle can be obtained by a multi-step process comprising at least two steps. Such a method is described for example in documents US2009 / 0149600 or EP0722961.

Regarding the plasticizer

The plasticizer can be a plasticizer commonly used in compositions based on polyamide (s).

Advantageously, a plasticizer is used which has good thermal stability so that no fumes are formed during the stages of mixing the various polymers and of processing the composition obtained.

In particular, this plasticizer can be chosen from: benzene sulfonamide derivatives such as n-butyl benzene sulfonamide (BBSA), ortho and para isomers of ethyl toluene sulfonamide (ETSA), N-cyclohexyl toluene sulfonamide and N- (2-hydroxypropyl) benzene sulfonamide (HP-BSA), esters of hydroxybenzoic acids such as 2-ethylhexyl para-hydroxybenzoate (EHPB) and 2-decylhexyl para-hydroxybenzoate (HDPB), esters or ethers of tetrahydrofurfuryl alcohol such as oligoethyleneoxy-tetrahydrofurfurylalcohol, and esters of citric acid or of hydroxymalonic acid, such as oligoethylene oxymalonate.

A preferred plasticizer is n-butyl benzene sulfonamide (BBSA).

Another more particularly preferred plasticizer is N- (2-hydroxy-propyl) benzene sulfonamide (HP-BSA). The latter in fact has the advantage of avoiding the formation of deposits at the level of the screw and / or of the extrusion die (“die tears”), during a step of transformation by extrusion.

It is of course possible to use a mixture of plasticizers.

Regarding the composite reinforcing layer and the polymer P2j The polymer P2j can be a thermoplastic polymer or a thermosetting polymer.

One or more composite reinforcement layers may or may be present.

Each of said layers consists of a fibrous material in the form of continuous fibers impregnated with a composition mainly comprising at least one thermoplastic polymer P2j, j corresponding to the number of layers present j is from 1 to 10, in particular from 1 to 5, in particular from 1 to 3, preferably j = 1.

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 and of the matrix of the composite. Advantageously, said at least one major polymer is present at more than 60% by weight, in particular at more than 70% by weight, particularly at more than 80% by weight, more particularly greater than or equal to 90% by weight, relative to the weight total composition,

Said composition can also comprise impact modifiers and / or additives.

The additives can be selected from an antioxidant, a heat stabilizer, a UV absorber, a light stabilizer, a lubricant, an inorganic filler, a flame retardant, a plasticizer and a colorant, except for a nucleating agent. Advantageously, said composition consists of said thermoplastic polymer P2j predominantly, 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 constituents of the composition being equal to 100% by weight.

Said at least one majority polymer of each layer may be identical or different. In one embodiment, a single major polymer is present at least in the composite reinforcing layer and which does not adhere to the sealing layer.

In one embodiment, each reinforcing layer comprises the same type of polymer, in particular an epoxy or epoxy-based resin.

P2j polymer

P2j thermoplastic polymer

The term thermoplastic, or thermoplastic polymer, is understood to mean a material which is generally solid at room temperature, which may be semi-crystalline or amorphous, in particular semi-crystalline and which softens during an increase in temperature, in particular after passing its temperature of glass transition (Tg) and flows at a higher temperature when it is amorphous, or may present a clear melting at the passage of its so-called melting temperature (Tf) when it is semi-crystalline, and which becomes solid again during 'a decrease in temperature below its crystallization temperature, Te, (for a semi-crystalline) and below its glass transition temperature (for an amorphous).

The number average molecular weight Mn of said thermoplastic polymer is preferably in a range of 10,000 to 40,000, preferably 10,000 to 30,000. These Mn values may correspond to inherent viscosities greater than or equal to 0.8 as determined in the m-cresol according to ISO 307: 2007 but changing the solvent (use of m-cresol instead of sulfuric acid and the temperature being 20 ° C).

As examples of semi-crystalline thermoplastic polymers suitable in the present invention, there may be mentioned: polyamides, in particular comprising an aromatic and / or cycloaliphatic structure, including copolymers, for example polyamide-polyether copolymers, polyesters, polyaryletherketones (PAEKs ), polyetherether ketones (PEEK), polyetherketone ketones (PEKK), polyetherketoneetherketone ketones (PEKEKK), polyimides in particular polyetherimides (PEI) or polyamide-imides, polylsulfones (PSU) in particular polyarylsulfones (PSU) polyphenyl sulfones

(PPSU), polyethersulfones (PES). semi-crystalline polymers are more particularly preferred, and in particular polyamides and their semi-crystalline copolymers.

The polyamide can be a homopolyamide or a copolyamide or a mixture thereof. Advantageously, the semi-crystalline polyamides are semi-aromatic polyamides, in particular 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 an amino acid, a unit obtained from a lactam and a unit corresponding to the formula (diamine in Ca). (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 ;

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 5 and 36, advantageously between 9 and 18, in particular a polyamide of formula A / 5T, A / 6T, A / 9T, A / 10T or A / 11 T, A being as defined above, in particular a polyamide chosen from a PA MPMDT / 6T, one PA11 / 10T, one PA 5T / 10T, one PA 11 / BACT, one PA 11 / 6T / 10T, one PA MXDT / 10T, one PA MPMDT / 10T, one PA BACT / 10T, one PA BACT / 6T, PA BACT / 10T / 6T, one PA 11 / BACT / 6T, PA 11 / MPMDT / 6T, PA 11 / MP M DT / 10T, PA 11 / BACT / 10T, one PA 11 / MXDT / 10T, one 11 / 5T / 10T.

T is terephthalic acid, MXD is m-xylylenediamine, MPMD is methylpentamethylene diamine, and BAC is bis (aminomethyl) cyclohexane. Said semi-aromatic polyamides defined above have in particular a Tg greater than or equal to 80 ° C.

P2j thermosetting polymer

The thermosetting polymers are chosen from epoxy or epoxy-based resins, polyesters, vinyl esters and polyurethanes, or a mixture of these, in particular epoxy or epoxy-based resins.

Advantageously, each composite reinforcing layer consists of a composition comprising the same type of polymer, in particular an epoxy resin or an epoxy-based resin. Said composition comprising said polymer P2j may be transparent to radiation suitable for welding.

In another embodiment, the winding of the composite reinforcing layer around the waterproofing layer is carried out in the absence of any subsequent welding.

Regarding the structure

Said multilayer structure therefore comprises at least one waterproofing layer and at least one composite reinforcing layer which is wrapped around the waterproofing layer and which may or may not adhere to each other.

Advantageously, said sealing and reinforcing layers do not adhere to each other and consist of compositions which respectively comprise different polymers.

However, said different polymers can be of the same type.

Thus, if one of the two composite sealing and reinforcing layers consists of a composition comprising an aliphatic polyamide, then the other layer consists of a composition comprising a polyamide which is not aliphatic and which is for example a semi-aromatic polyamide so as to have a high tg polymer as the matrix of the composite reinforcement.

Said multilayer structure can include up to 10 waterproofing layers and up to

10 layers of composite reinforcement of different types.

Advantageously, said structure is devoid of any binder or adhesive layer, whether between the sealing layers, or between the composite reinforcing layers, or between the outermost sealing layer and the innermost composite reinforcing layer. .

It is obvious that said multilayer structure is not necessarily symmetrical and that it can therefore include more waterproofing layers than composite layers or vice versa, but there cannot be alternation of layers and of reinforcing layer. Advantageously, said multilayer structure comprises one, two, three, four, five, six, seven, eight, nine or ten sealing layers and one, two, three, four, five, six, seven, eight, nine or ten layers composite reinforcement.

Advantageously, said multilayer structure comprises one, two, three, four or five waterproofing layers and one, two, three, four or five composite reinforcement layers. Advantageously, said multilayer structure comprises one, two or three waterproofing layers and one two or three composite reinforcement layers.

Advantageously, they consist of compositions which respectively comprise different polymers. Advantageously, they consist of compositions which respectively comprise polyamides corresponding to polyamides P1i and an epoxy resin or based on epoxy P2j.

In one embodiment, said multilayer structure comprises a single waterproofing layer and several reinforcing layers, said adjacent reinforcing layer being wrapped around said waterproofing layer and the other reinforcing layers being wrapped around the reinforcing layer. directly adjacent.

In another embodiment, said multilayer structure comprises a single reinforcing layer and several sealing layers, said reinforcing layer being wrapped around said adjacent sealing layer.

In an advantageous embodiment, said multilayer structure comprises a single waterproofing layer and a single composite reinforcing layer, said reinforcing layer being wrapped around said waterproofing layer.

All combinations of these two layers are therefore within the scope of the invention, provided that at least said innermost composite reinforcing layer is wrapped around said outermost adjacent sealing layer, the other layers adhering or not between them or not.

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

By the same type of polymer is meant, for example, a polyamide which can be an identical or different polyamide depending on the layers.

Advantageously, said polymer P1i is a polyamide and said polymer P2j is an epoxy or epoxy-based resin.

Advantageously, the polyamide P1i is identical for all the waterproofing layers. Advantageously, said polymer P1i is a long-chain aliphatic polyamide, in particular PA1010, PA 1012, PA 1212, PA11, PA12, in particular PA 11 or PA12. Advantageously, the polyamide P1i is a long-chain semi-aromatic polyamide, in particular PA 11 / 5T, PA 11 / 6T or PA 11 / 10T. Obviously in this case, the level of 11 must be chosen judiciously so that the Tm of said polymers is less than 280 ° C, preferably 265 ° C.

Advantageously, in said multilayer structure, each reinforcing layer consists of a composition comprising the same type of polymer P2j, in particular an epoxy or epoxy-based resin.

Advantageously, the P2j polyamide is identical for all the reinforcing layers. Advantageously, in said multilayer structure, each sealing layer consists of a composition comprising the same type of polymer P1i, in particular a polyamide and each reinforcing layer consists of a composition comprising the same type of polymer P2j, in particular an epoxy resin or an epoxy-based resin. Advantageously, said polymer P1 i is a long-chain aliphatic polyamide, in particular PA1010, PA 1012, PA 1212, PA11, PA12, in particular PA 11 or PA12 and said polymer P2j is a semi-aromatic polyamide, in particular chosen from a PA MPMDT / 6T, one PA11 / 10T, one PA 11 / BACT, one PA 5T / 10T, one PA 11 / 6T / 10T, one PA MXDT / 10T, one PA MPMDT / 10T, one PA BACT / 10T, one PA BACT / 6T, PA BACT / 10T / 6T, one PA 11 / BACT / 6T, PA 11 / MPMDT / 6T, PA 11 / MPMDT / 10T, PA 11 / BACT / 10T, one PA and 11 / MXDT / 10T.

In one embodiment, said multilayer structure consists of a single reinforcing layer and a single sealing layer in which said polymer P1 i is a long-chain aliphatic polyamide, in particular PA1010, PA 1012, PA 1212 , PA11, PA12, in particular PA 11 or PA12 and said polymer P2j is a semi-aromatic polyamide, in particular chosen from a PA MPMDT / 6T, a PA11 / 10T, a PA 11 / BACT, a PA 5T / 10T, a PA 11 / 6T / 10T, one PA MXDT / 10T, one PA MPMDT / 10T, one PA BACT / 10T, one PA BACT / 6T, PA BACT / 10T / 6T, one PA 11 / BACT / 6T, PA 11 / MPMDT / 6T,

PA 11 / MP M DT / 10T, PA 11 / BACT / 10T and a PA 11 / MXDT / 10T.

In another embodiment, said multilayer structure consists of a single reinforcing layer and a single sealing layer in which said polymer P1 i is a long-chain aliphatic polyamide, in particular PA1010, PA 1012, PA 1212, PA12, in particular PA12 and said polymer P2j is a semi-aromatic polyamide, in particular chosen from a PA MPMDT / 6T, a PA PA11 / 10T, a PA 11 / BACT, a PA 5T / 10T and a PA 11 / 6T / 10T, one PA MXDT / 10T, one PA MPMDT / 10T, one PA BACT / 10T, one PA BACT / 6T, PA BACT / 10T / 6T, one PA 11 / BACT / 6T, PA 11 / MPMDT / 6T, PA 11 / MPMDT / 10T, PA 11 / BACT / 10T and a PA 11 / MXDT / 10T.

In yet another embodiment, the multilayer structure consists of a single reinforcing layer and a single sealing layer in which said polymer P1i is a long-chain aliphatic polyamide, in particular PA1010, PA 1012, PA 1212, PA11, PA12, or semi-aromatic, in particular chosen from polyamide 11 / 5T or 11 / 6T or 11 / 10T, MXDT / 10T, MPMDT / 10T and BACT / 10T, in particular PA 11 or PA12 and said polymer P2j is an epoxy or epoxy-based resin.

In another embodiment, the multilayer structure consists of a single reinforcing layer and a single sealing layer in which said polymer P1 i is a long-chain aliphatic polyamide, in particular PA1010, PA 1012, PA 1212, PA12, or semi-aromatic, in particular chosen from polyamide 11 / 5T or 11 / 6T or 11 / 10T, MXDT / 10T, MPMDT / 10T and BACT / 10T, in particular PA12 and said polymer P2j is an epoxy or epoxy resin. Advantageously, said multilayer structure further comprises at least one outer layer made of a continuous fiberglass fibrous material impregnated with a transparent amorphous polymer, said layer being the outermost layer of said multilayer structure.

Said outer layer is a second but transparent reinforcing layer which makes it possible to put an inscription on the structure.

Said outer layer in no way corresponds to the layer located above the outermost composite reinforcing layer of polyamide polymer, the structure of which is not mentioned above.

Regarding the fibrous material

Regarding the constituent fibers of said fibrous material, they are in particular fibers of mineral, organic or plant origin.

Advantageously, said fibrous material can be sized or not sized.

Said fibrous material can therefore comprise up to 3.5% by weight of an organic material (thermosetting or thermoplastic resin type) called sizing.

Among the fibers of mineral origin, mention may be made of carbon fibers, glass fibers, basalt or basalt-based fibers, silica fibers, or silicon carbide fibers, for example. Among the fibers of organic origin, mention may be made of fibers based on a thermoplastic or thermosetting polymer, such as semi-aromatic polyamide fibers, aramid fibers or polyolefin fibers, for example. Preferably, they are based on an amorphous thermoplastic polymer and have a glass transition temperature Tg greater than the Tg of the polymer or mixture of thermoplastic polymer constituting the pre-impregnation matrix when the latter is amorphous, or greater than the Tm of the polymer or mixture of thermoplastic polymer constituting the prepreg matrix when the latter is semi-crystalline. Advantageously, they are based on a semi-crystalline thermoplastic polymer and have a melting point Tm greater than the Tg of the polymer or mixture of thermoplastic polymer constituting the prepreg matrix when the latter is amorphous, or greater than the Tm. of the polymer or mixture of thermoplastic polymer constituting the prepreg matrix when the latter is semi-crystalline. Thus, there is no risk of fusion for the organic fibers constituting the fibrous material during impregnation with the thermoplastic matrix of the final composite. Among the fibers of plant origin, mention may be made of natural fibers based on flax, hemp, lignin, bamboo, silk, in particular spider silk, sisal, and other cellulose 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 the impregnation of the thermoplastic polymer matrix.

The fibrous material can also be fabric, braided or woven with fibers.

It can also correspond to fibers with retaining threads.

These constitution fibers can be used alone or in mixtures. Thus, organic fibers can be mixed with mineral fibers to be pre-impregnated with thermoplastic polymer powder and to form the pre-impregnated fibrous material.

The rovings of organic fibers can have several grammages. They can also have several geometries. The fibers constituting the fibrous material can also be in the form of a mixture of these reinforcing fibers of different geometries. Fibers are continuous fibers.

Preferably, the fibrous material is chosen from glass fibers, carbon fibers, basalt or basalt-based fibers, or a mixture of these, in particular carbon fibers.

It is used as a wick or several wicks.

According to another aspect, the present invention relates to a method of manufacturing a multilayer structure as defined above, characterized in that it comprises a step of preparing the sealing layer by extrusion blow molding, by rotational molding, by injection and / or extrusion.

In one embodiment, said method of manufacturing a multilayer structure comprises a step of filament winding of the reinforcing layer as defined above around the sealing layer as defined above.

All of the features detailed above also apply to the process.

Brief description of the figures.

Figure 1 shows the notched Charpy impact at -40 ° C according to ISO 179-1: 2010 of four liners: from left to right PA11, PA12, PA6 and PA66.

Figure 2 shows the hydrogen permeability at 23 ° C of PA12 and HDPE liners.

It is expressed in cc.mm/m ² .24h.atm. It can be expressed in cc.25p / m ² .24h.Pa.

The permeability must then be multiplied by 101325.

Figure 3 shows the notched Charpy shock at -40 ° C according to ISO 179-1: 2010 for PA11 and PA12 liners: for each group of histograms, PA11 is on the left and PA12 is on the right. The first group corresponds to 0% plasticizer, the second group to 7% plasticizer and the last group to 12% plasticizer.

EXAMPLES

In all the examples, the tanks are obtained by rotational molding of the sealing layer (liner) at a temperature suited to the nature of the thermoplastic resin used. In the case of the epoxy resin or epoxy-based composite reinforcement, a wet filament winding process is then used which consists in winding fibers around the liner, which fibers are pre-impregnated in an epoxy bath. liquid or a liquid epoxy-based bath. The reservoir is then polymerized in an oven for 2 hours.

In all other cases, then a fibrous material impregnated with the thermoplastic resin (tape) is used. This tape is deposited by filament winding using a robot comprising a 1500W power laser heater at a speed of 12m / min and there is no polymerization step.

Example 1: Notched Charpy shock at -40 ° C according to ISO 179-1: 2010

Two long chain liners of PA11 and PA12 and two short chain liners were prepared by rotational molding as above.

These four liners were notched Charpy shock tested at -40 ° C and the results are shown in Figure 1.

The cold resistance of long-chain liners is much better than that of short-chain liners PA6 and PA66.

Example 2:

Permeability of PA 11 and PA12 (Arkema) and HDPE (Marlex® HMN TR-942 (Chevron Phillips) liners)

Two long chain liners: one in PA11 (Arkema) and the second in PA12 (Arkema) and one liner in HDPE were prepared by rotational molding and the hydrogen permeability at 23 ° C was tested.

This consists of sweeping the upper face of the film with the test gas (Hydrogen) and of measuring by gas chromatography the flow which diffuses through the film into the lower part, swept by the carrier gas: Nitrogen The conditions experiments are presented in Table 1:

[Tables 1]

The results are presented in Figure 2 and show that the PA11 liner and the PA12 liner both have a much lower permeability than an H DPE liner. Example 3: influence of the proportion of plasticizer (N-butyl benzene sulfonamide:

BBSA) on the notched Charpy impact at -40 ° C according to ISO 179-1: 2010

Two liners PA11 and PA12 without plasticizer or comprising 7 or 12% plasticizer (BBSA) relative to the total weight of the composition were prepared by rotational molding.

These liners were notched Charpy impact tested at -40 ° C according to ISO 179-1: 2010 and the results are shown in Figure 3.

The plasticizer has a deleterious cold effect, it weakens the structure and increases the permeability, in particular by 50% with 7% BBSA.

Example 4

Influence of the proportion of impact modifier (“LT cocktail” having the following composition: lotader® 4700 (50%) + lotader® AX8900 (25%) + lucalene® 3110 (25%)) on the permeability to hydrogen of the liner PA12.

The hydrogen permeability of the PA12 liner, without plasticizer and in the presence or absence of impact modifier was tested and is reported in Table 2.

[Tables 2]

The permeability can also be expressed in (cc.25p / m ² .24h.Pa).

The permeability must then be multiplied by 101325.

The results show that the proportion of impact modifier influences the hydrogen permeability.

The greater the proportion of impact modifier, the more the permeability increases. Example 5 Type IV hydrogen storage tank, composed of an epoxy composite reinforcement (Tg 120 ° C) T700SC31E carbon fibers (produced by Toray) and a waterproofing layer of PA11.

The operating temperature is sufficient for rapid filling of the tank, especially in 3 to 5 minutes.

Example 6 (counter example):

Type IV hydrogen storage tank, composed of an epoxy composite reinforcement (Tg 120 ° C) T700SC31E carbon fibers (produced by Toray) and an HDPE waterproofing layer.

The operating temperature is too low for rapid filling of the tank, especially in 3 to 5 minutes.

Example 7: Type IV hydrogen storage tank, composed of a reinforcement of BACT / 10T carbon fiber T700SC31 E composite (produced by Toray) and a waterproofing layer of PA12.

The BACT / 10T type composition chosen has a melting point, Tm, of 283 ° C, a crystallization temperature, Te, of 250 ° C and a glass transition temperature of 164 ° C.

A PA BACT / 10T-based composite exhibits a high Tg matrix, but without having long crosslinking, of the 8h type at 140 ° C.

Consequently, after the fiber removal, the tank is finished, which saves 8 hours of process time.

Claims

1. Multilayer structure intended for the transport, distribution and storage of hydrogen, comprising, from the inside to the outside, at least one waterproofing layer (1) and at least one composite reinforcing layer (2 ), said innermost composite reinforcing layer being wrapped around said outermost adjacent sealing layer (1), said sealing layers being made of a composition comprising: more than 50% by weight relative to total weight of the composition of at least one long-chain thermoplastic polyamide polymer P1i, i = 1 to n, n being the number of semi-crystalline waterproofing layers including the Tf, as measured according to ISO 11357-3: 2013, is greater than 160 ° C, in particular greater than 170 ° C, said long-chain polyamide thermoplastic polymer having an average number of carbon atoms per nitrogen atom greater than 9, excluding a polyether block amide (PEBA), up to 50% by weight of impact modifier, in particular up to 'less than 15% by weight of impact modifier, in particular up to 12% by weight of impact modifier relative to the total weight of the composition, up to 1.5% by weight of plasticizer relative to the total weight of the composition, said composition being devoid of nucleating agent, said at least one thermoplastic polyamide polymer of each sealing layer possibly being the same or different, and at least one of said composite reinforcing layers being made of a fibrous material in the form of continuous fibers impregnated with a composition comprising more than 50% by weight relative to the total weight of the composition of at least one polymer P2j, j = 1 to m, m being the number of reinforcing layers, in particular one epoxy or epoxy-based resin, said structure being devoid of a layer of polyamide polymer, said layer of polyamide polymer being the outermost and adjacent to the outermost layer of composite reinforcement.

2. Multilayer structure according to claim 1, characterized in that each sealing layer comprises the same type of polyamide.

3. Multilayer structure according to one of claims 1 or 2, characterized in that each reinforcing layer comprises the same type of polymer, in particular an epoxy resin or based on epoxy.

4. Multilayer structure according to claim 3, characterized in that each sealing layer comprises the same type of polyamide and each reinforcing layer comprises the same type of polymer, in particular an epoxy or epoxy-based resin.

5. Multilayer structure according to one of claims 1 to 4, characterized in that it has a single sealing layer and a single reinforcing layer.

6. Multilayer structure according to one of claims 1 to 5, characterized in that said PU polymer is a long chain aliphatic polyamide, in particular PA1010, PA 1012, PA 1212, PA11, PA12, in particular PA 11 or PA12 or semi - aromatic, in particular chosen from polyamide 11 / 5T or 11 / 6T or 11 / 10T, MXDT / 10T, MPMDT / 10T and BACT / 10T.

7. Multilayer structure according to one of claims 1 to 6, characterized in that said polymer P2j is an epoxy resin or based on epoxy.

8. Multilayer structure according to one of claims 6 or 7, characterized in that said multilayer structure consists of a single reinforcing layer and a single sealing layer in which said PU polymer is a long-lasting aliphatic polyamide. chain, in particular PA1010, PA 1012, PA 1212, PA11, PA12, or semi-aromatic, in particular chosen from polyamide 11 / 5T or 11 / 6T or 11 / 10T, MXDT / 10T, MPMDT / 10T and BACT / 10T, in particular PA 11 or PA12 and said polymer P2j is an epoxy resin or an epoxy-based resin.

9. Multilayer structure according to one of claims 1 to 8, characterized in that the fibrous material of the composite reinforcing layer is chosen from glass fibers, carbon fibers, basalt fibers or based on basalt, or a mixture thereof, in particular carbon fibers.

10. Multilayer structure according to one of claims 1 to 9, characterized in that said structure further comprises at least one outer layer consisting of a continuous fiberglass fibrous material impregnated with a transparent amorphous polymer, said layer being the outermost layer of said multilayer structure.

11. A method of manufacturing a multilayer structure as defined in one of claims 1 to 10, characterized in that it comprises a step of preparing the sealing layer by extrusion blow molding, by rotational molding, by injection and / or by extrusion.

12. A method of manufacturing a multilayer structure according to claim 11, characterized in that it comprises a step of filament winding of the reinforcing layer as defined in claim 1 around the sealing layer as defined. in claim 1.