EP4221975A1

EP4221975A1 - Multi-layer structure for storing hydrogen

Info

Publication number: EP4221975A1
Application number: EP21798078.8A
Authority: EP
Inventors: Jean-Jacques Flat; Patrick Dang
Original assignee: Arkema France SA
Current assignee: Arkema France SA
Priority date: 2020-10-01
Filing date: 2021-09-28
Publication date: 2023-08-09
Also published as: US20230356514A1; KR20230079128A; MX2023003270A; CA3192554A1; WO2022069826A1; FR3114768B1; FR3114768A1; JP2023543906A; CN116406326A

Abstract

Multi-layer structure for 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), at least the innermost sealing layer being made of a composition comprising, relative to the total weight of the composition: a. 20.5 to 99.845% by weight of at least one polyamide; b. 0.005 to 0.5% by weight of at least one catalyst; c. 0.05 to 1% by weight of at least one heat stabiliser; d. 0.1 to 3% by weight of at least one oligo- or poly-carbodiimide; e. 0 to 1.5% by weight of at least one plasticiser; f. 0 to less than 15% by weight of at least one polyolefin, in particular from 1 to less than 15% by weight; g. 0 to 30% of at least one additive, and at least one of the composite reinforcing layers being made of a fibrous material in the form of continuous fibres impregnated with 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.

Description

DESCRIPTION

TITLE: MULTILAYER STRUCTURE FOR HYDROGEN STORAGE [Technical field]

This patent application relates to composite multilayer structures for the storage of hydrogen, and their method of manufacture.

[prior technique]

Hydrogen tanks are a subject that is currently attracting a lot of interest from many manufacturers, particularly in the automotive field. One of the goals sought is to offer less and less polluting vehicles. 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 where the battery is located in the vehicle, it may need to be protected from impact and the external environment, which may 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, recharge times much longer than the durations tank filling, as well as a problem of electricity production in the various 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 envelope (liner or sealing layer) which must prevent the permeation of hydrogen. One of the types of tanks 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 to manage them independently of each other. In this type of tank, the liner (or sealing sheath) in thermoplastic resin is associated with a reinforcing structure made up of fibers (glass, aramid, carbon) also called sheath or reinforcing layer which make it possible to work at much higher pressures. all in reducing the mass and avoiding the risk of explosive rupture in the event of severe external attacks.

The liners must have certain basic characteristics:

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

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 larger tank which then reaches a temperature of about 100°C.

The performance and safety evaluation 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 defect of having a too low melting temperature and a high hydrogen permeability, which represents a problem with the new requirements in terms of thermal resistance and does not allow to increase the filling speed of the tank.

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

WO2018155491 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, 1 to 3% of plasticizer or devoid of plasticizer, and which has hydrogen barrier properties, good flexibility and durability at low temperature. However, this structure is suitable for pipes for the transport of hydrogen but not for the storage of hydrogen and, moreover, this composition has a viscosity that is too progressive to be stable for transformation by extrusion blow molding, a transformation technology which can generate very high melt residence times (up to 20 minutes) at high temperature within the accumulation blocks.

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

These problems are solved by the provision of a multilayer structure of the present invention intended for the 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 storage of hydrogen, comprising, from the inside outwards, at least one sealing layer (1) and at least one composite reinforcement layer (2), said innermost composite reinforcing layer being wrapped around said outermost adjacent sealing layer (1), at least said innermost sealing layer consisting of a composition comprising, relative to the total weight of the composition : has. 20.5 to 99.845% by weight of at least one polyamide; b. 0.005 to 0.5% by weight of at least one catalyst; vs. 0.05 to 1% by weight of at least one heat stabilizer; d. 0.1 to 3% by weight of at least one oligo- or poly-carbodiimide; e. 0 to 1.5% by weight of at least one plasticizer, f. 0 to less than 15% by weight of at least one polyolefin; g. 0 to 30% of at least one additive, the sum of constituents a to g representing 100% by weight, and at least one of said layers of composite reinforcement consisting of a fibrous material in the form of continuous fibers impregnated with a composition mainly comprising at least one polymer P2j, j=1 to m, m being the number of reinforcing layers, in particular an epoxy or epoxy-based resin.

Advantageously, said structure is devoid of nucleating agent.

Advantageously, said structure does not have an outermost layer adjacent to the outermost layer of composite reinforcement made of polyamide polymer. Advantageously, said structure is devoid of nucleating agent and is devoid of an outermost layer and adjacent to the outermost layer of composite reinforcement made of polyamide polymer.

The inventors have therefore unexpectedly found that the use of a semi-crystalline long-chain polyamide thermoplastic polymer, comprising a limited proportion of impact modifier and plasticizer, a catalyst, a heat stabilizer and an oligo- or poly-carbodiimide allowed not only to obtain compositions for the layer sealants, which have good viscosities, that is to say viscosities in the molten state that are sufficiently high to be able to be transformed, in particular by extrusion-blow molding, without however increasing the viscosity in solution, in other words the viscosity inherent, said viscosity in the molten state being moreover sufficiently stable during the transformation, in particular for extrusion blow molding. They also found that the combination of said sealing layer with a different polymer for the matrix of the composite and in particular an epoxy or epoxy-based resin, said composite being wound on the sealing layer, also allowed the obtaining a structure adapted to the storage of hydrogen, and in particular an increase in the maximum temperature of use which can go up to 120° C., thus making it possible to increase the speed of filling of 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 reinforcing layer or a sealing layer and a reinforcing layer. The multilayer structure is therefore understood to exclude a pipe or a tube.

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

The sealing layer or layers are the innermost layers compared to the composite reinforcement layers which are the outermost layers.

The tank can be a tank for mobile hydrogen storage, i.e. on a truck for transporting hydrogen, on a car for transporting hydrogen and supplying hydrogen to a fuel cell for example, on a train for hydrogen supply or on a drone for hydrogen supply, but it can also be a stationary hydrogen storage tank in a station for hydrogen distribution 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).

The composite reinforcement layer(s) is (are) wound 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 several layers are present, the polymers are different.

When the polymers of the reinforcing layers are identical, there may be several layers present, but advantageously a single reinforcing layer is present and which then has at least one complete winding around the sealing layer. This totally 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 resist the change in internal pressure.

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

When only a sealing layer and a composite reinforcement layer are present, thus leading to a two-layer multilayer structure, then these two layers can adhere to each other, in direct contact with each other , in particular due to the winding of the composite reinforcement layer on the sealing layer.

When several layers of sealing are present and/or several layers of composite reinforcement, then the outermost layer of said sealing layers, and therefore opposite the layer in contact with the hydrogen, may or may not adhere to the innermost layer of said composite reinforcement.

The other layers of composite reinforcement may also adhere or not to each other.

The other sealing layers may or may not adhere to each other.

Advantageously, only a sealing layer and a reinforcing layer are present and do not adhere to each other.

Advantageously, only a sealing layer and a reinforcement layer are present and do not adhere to each other and the reinforcement 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 or epoxy-based resin.

In one embodiment, only a sealing layer and a reinforcement layer are present and do not adhere to each other and the reinforcement 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 specification means that the epoxy constitutes at least 50% by weight of the matrix.

With regard to the waterproofing layer(s) and the composition

One or more sealing layers may be present.

From 1 to 10 layers may be present, in particular from 1 to 5, in particular from 1 to 3, preferentially only 1 sealing layer is present.

At least said innermost sealing layer consists of a composition comprising, relative to the total weight of the composition: a. 20.5 to 99.845% by weight of at least one polyamide; b. 0.005 to 0.5% by weight of at least one catalyst; vs. 0.05 to 1% by weight of at least one heat stabilizer; d. 0.1 to 3% by weight of at least one oligo- or poly-carbodiimide; e. 0 to 1.5% by weight of at least one plasticizer, f. 0 to less than 15% by weight of at least one polyolefin; g. 0 to 30% of at least one additive, the sum of constituents a to g representing 100% by weight.

In one embodiment, said composition consists of: a. 20.5 to 99.845% by weight of at least one polyamide; b. 0.005 to 0.5% by weight of at least one catalyst; vs. 0.05 to 1% by weight of at least one heat stabilizer; d. 0.1 to 3% by weight of at least one oligo- or poly-carbodiimide; e. 0 to 1.5% by weight of at least one plasticizer, f. 0 to less than 15% by weight of at least one polyolefin; g. 0 to 30% of at least one additive, the sum of constituents a to g representing 100% by weight.

The catalyst:

The term “catalyst” designates a polycondensation catalyst such as an inorganic or organic acid.

The proportion by weight of catalyst is between about 50 ppm to about 5000 ppm, in particular from about 100 to about 3000 ppm relative to the total weight of the composition. Advantageously, the catalyst is chosen from phosphoric acid (H3PO4), phosphorous acid (H3PO3), hypophosphorous acid (H3PO2), or a mixture thereof. Advantageously, the proportion by weight of catalyst is between about 50 ppm to about 5000 ppm, in particular from about 100 to about 3000 ppm relative to the total weight of the composition and said catalyst is chosen from phosphoric acid (H3PO4 ), phosphorous acid (H3PO3), hypophosphorous acid (H3PO2), or a mixture thereof. Advantageously, the catalyst is chosen from phosphoric acid (H3PO4), phosphorous acid (H3PO3) in a proportion of approximately 100 to approximately 3000 ppm.

Heat stabilizer:

This stabilizer can be an organic stabilizer or more generally a combination of organic stabilizers, such as a primary antioxidant of the phenol type (for example of the type of that of irganox 245 or 1098 or 1010 from the company Ciba), a secondary antioxidant of the phosphite and even possibly other stabilizers such as a HALS, which means Hindered Amine Light Stabilizer or hindered amine type light stabilizer (for example Tinuvin 770 from the company Ciba), a phenol phosphite type antioxidant such as ANOXONDB TL89, a anti-UV (for example Tinuvin 312 from Ciba), a phenolic or phosphorus-based stabilizer. It is also possible to use antioxidants of the type amine such as Naugard 445 from the company Crompton or even polyfunctional stabilizers such as Nylostab S-EED from the company Clariant.

This stabilizer can also be an inorganic stabilizer, such as a copper-based stabilizer. By way of example of such inorganic stabilizers, mention may be made of copper halides and acetates. Incidentally, one can possibly consider other metals such as silver, but these are known to be less effective. These copper-based compounds are typically associated with alkali metal halides, particularly potassium.

Advantageously, the heat stabilizer is an organic stabilizer.

The heat stabilizer is in a proportion of about 0.05% to about 1%, in particular from about 0.05% to about 0.3% by weight relative to the total weight of the composition. Advantageously, the proportion by weight of catalyst is between about 50 ppm to about 5000 ppm, in particular from about 100 to about 3000 ppm relative to the total weight of the composition, the thermal stabilizer is in a proportion of about 0, 0.05% to approximately 1%, in particular from approximately 0.05% to approximately 0.3% by weight relative to the total weight of the composition, and said catalyst being chosen from phosphoric acid (H3PO4), acid phosphorous (H3PO3), hypophosphorous acid (H3PO2), or a mixture of these. Advantageously, the catalyst is chosen from phosphoric acid (H3PO4), phosphorous acid (H3PO3) in a proportion of approximately 100 to approximately 3000 ppm.

Carbodiimide:

Carbodiimide is a conventionally known carbodiimide oligomer and polymer and can be prepared by polymerization of diisocyanates.

This reaction can be accelerated by catalysts and products with elimination of carbon dioxide (J. Org. Chem, 28, 2069 (1963). J. Am. Chem. Soc. 84, 3673 (1962); Chem. Rev. , 81, 589 (1981);Ange.Chem., 93, 855 (1981)).

NCO end group reagents may include a CH, NH or OH reactive compound, for example esters of malonic acid, caprolactam, alcohols or phenols.

Alternatively, mixtures of mono- and diisocyanates can be polymerized to obtain oligo- or polycarbodiimides containing essentially unreactive end groups.

The carbodiimide used is an oligo or polycarbodiimide of general formula:

R1 -N=C=N(-R2-N=C=N-)n-R3 in which R1 and R3 represent C1 to C20 alkyls, C5 to C20 cycloalkyls, aryls having from 6 to 20 carbon atoms or aralkyls having 7 to 20 carbon atoms, each being optionally substituted by an isocyanate group optionally comprising a CH, an NH or an OH reactive compound; R2 represents alkylene having 2 to 20 carbon atoms, cycloalkylene having 5 to 20 carbon atoms, arylene having 6 to 20 carbon atoms or aralkylene having 7 to 20 carbon atoms; n = 1 to 100, preferably 2 to 80 and preferably 3 to 70.

The oligo- or polycarbodiimide can be a homopolymer or a copolymer, for example a copolymer of 2,4-diisocyanato-1,3,5-triisopropylbenzene and 1,3-diisocyanato-3,4-diisopropylbenzene.

The oligo- or polycarbodiimide can also be chosen from those described in US 5,360,888.

Suitable oligo and polycarbodiimides can be obtained from commercially available sources such as Rhein Chemie, Raschig or Ziko.

Advantageously, the proportion by weight of oligo- or poly-carbodiimide used is between approximately 0.1 and approximately 3%, in particular from 0.5 to 2%, in particular approximately equal to 1% relative to the total weight of the composition.

Advantageously, the oligo- or poly-carbodiimide is chosen from Stabilizers, in particular Stabilizer® 9000, Stabaxol®, in particular a stabaxol® P, in particular Stabaxol® P100 or Stabaxol® P400, or a mixture of those -this.

Advantageously, the present invention therefore relates to the structure defined above comprising an innermost sealing layer consisting of a composition comprising, relative to the total weight of the composition, at least one catalyst, at least one heat stabilizer, and at least an oligo- or poly-carbodiimide in a proportion of approximately 0.1 to approximately 3%, in particular of 0.5 to 2%, in particular approximately equal to 1% by weight relative to the total weight of the composition, with a matrix comprising at least one thermoplastic polymer, in particular a polyamide, the said oligo- or poly-carbodiimide being chosen from a Stabilizer, in particular Stabilizer® 9000, a Stabaxol®, in particular a stabaxol® P, in particular Stabaxol® P100 or Stabaxol ® P400, or a mixture of these and, where appropriate, at least one plasticizer up to 1.5% by weight and/or at least one polyolefin up to 15% by weight.

Advantageously, the proportion by weight of catalyst comprised from approximately 50 ppm to approximately 5000 ppm, in particular from approximately 100 to approximately 3000 ppm relative to the total weight of the composition, and the oligo- or poly-carbodiimide is in proportion from approximately 0.1 to approximately 3%, in particular from 0.5 to 2%, in particular approximately equal to 1% by weight relative to the total weight of the composition, with a matrix comprising at least one thermoplastic polymer, in particular a polyamide, said catalyst being chosen from phosphoric acid (H3PO4), phosphorous acid (H3PO3), hypophosphorous acid (H3PO2), or a mixture thereof and said oligo- or poly-carbodiimide being chosen from a Stabilize, in particular the Stabilizer® 9000, a Stabaxol®, in particular a Stabaxol® P, in particular Stabaxol® P100 or Stabaxol® P400, or a mixture of these.

Advantageously, the catalyst is chosen from phosphoric acid (H3PO4), phosphorous acid (H3PO3) in a proportion of approximately 100 to approximately 3000 ppm. Advantageously, the heat stabilizer is in a proportion of about 0.05% to about 1%, in particular from about 0.05% to about 0.3% by weight relative to the total weight of the composition, and the oligo - or poly-carbodiimide is in a proportion of approximately 0.1 to approximately 3%, in particular from 0.5 to 2%, in particular approximately equal to 1% by weight relative to the total weight of the composition, and said oligo- or polycarbodiimide being chosen from a Stabilizer, in particular Stabilizer® 9000, a Stabaxol®, in particular a stabaxol® P, in particular Stabaxol® P100 or Stabaxol® P400, or a mixture of these.

Advantageously, the proportion by weight of catalyst comprised from approximately 50 ppm to approximately 5000 ppm, in particular from approximately 100 to approximately 3000 ppm relative to the total weight of the composition, the heat stabilizer is in a proportion of approximately 0.05 % to approximately 1%, in particular from approximately 0.05% to approximately 0.3% by weight relative to the total weight of the composition, and the oligo- or poly-carbodiimide is in a proportion of approximately 0.1 to approximately 3%, in particular from 0.5 to 2%, in particular approximately equal to 1% by weight relative to the total weight of the composition, said catalyst being chosen from phosphoric acid (H3PO4), phosphorous acid ( H3PO3), hypophosphorous acid (H3PO2), or a mixture thereof, said oligo- or poly-carbodiimide being chosen from a Stabilizer, in particular Stabilizer® 9000, a Stabaxol®, in particular a stabaxol® P, in in particular Stabaxol® P100 or Stabaxol® P400, or a mixture thereof.

Advantageously, the catalyst is chosen from phosphoric acid (H3PO4), phosphorous acid (H3PO3) in a proportion of approximately 100 to approximately 3000 ppm. Additives:

Additives can be selected from other polymer, UV absorber, light stabilizer, lubricant, inorganic filler, flame retardant, colorant, carbon black and carbon nanofillers, except for a nucleating agent, in particular the additives are chosen from a UV absorber, a light stabilizer, a lubricant, an inorganic filler, a flame retardant, a colorant, carbon black and carbon nanofillers, at the exception of a nucleating agent.

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

In one embodiment, a single polyamide is present at least in the sealing layer which does not adhere to the composite reinforcement layer.

Polyamide The polyamide is in particular a semi-crystalline, in particular aliphatic or semi-aromatic, in particular aliphatic, polyamide.

The term "semi-crystalline polyamide" means a material that is generally solid at room temperature, and which softens when the temperature rises, in particular after passing its glass transition temperature (Tg), and which may exhibit a sharp melting on passing of 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 weight Mn of said semi-crystalline polyamide is preferably in a range ranging 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 at inherent viscosities greater than or equal to 0.8 as determined in 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).

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

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

Polyamide 10 (PA10), Polyamide 11 (PA11), Polyamide 12 (PA12), Polyamide 1010 (PA1010), Polyamide 1012 (PA1012), Polyamide 1212 (PA1012), or a mixture of these 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 of these or a copolyamide of these, in particular PA11 and the 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 chosen from: polyamide 12 (PA12), polyamide 1012 (PA1012), polyamide 1212 (PA1012), or a mixture of these or a copolyamide of these, in particular PA12.

In another embodiment, said semi-crystalline polyamide thermoplastic polymer is a semi-aromatic semi-crystalline polyamide, in particular with a long chain, that is to say a polyamide having an average number of carbon atoms per carbon atom. nitrogen 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 11/1 OT, MXDT/10T, MPMDT/10T and BACT/1 OT.

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

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

Regarding the polyolefin

In one embodiment, PEBAs are excluded from the definition of polyolefins.

The polyolefin 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 non-functionalized polyolefins (B2) have been described below.

A non-functionalized 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:

- homopolymers and copolymers of polyethylene, 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 possibly reaching 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 possibly being totally or partially neutralized by metals such as Zn, etc.) or else 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 of 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 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;

- ethylene and vinyl acetate (EVA) and alkyl (meth)acrylate copolymers, containing up to 40% by weight of comonomers.

The functionalized polyolefin (B1) can also be chosen from ethylene/propylene copolymers with a majority of propylene grafted with maleic anhydride then condensed with monoamino 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 saturated carboxylic acid vinyl ester 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 this last type, mention may be made of the following copolymers, in which the ethylene preferably represents at least 60% by weight and in which 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 alkyl (meth)acrylate/(meth)acrylic acid or maleic anhydride or glycidyl methacrylate copolymers.

In the above copolymers, the (meth)acrylic acid can be salified with Zn or Li. The term "alkyl (meth)acrylate" in (B1) or (B2) denotes alkyl methacrylates and acrylates C1 to C8, and can be selected from methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, ethyl-2-hexyl acrylate, l cyclohexyl acrylate, methyl methacrylate and ethyl methacrylate.

Furthermore, the aforementioned polyolefins (B1) can also be crosslinked by any appropriate process or agent (diepoxy, diacid, peroxide, etc.); the term functionalized polyolefin also includes mixtures of the aforementioned polyolefins with a difunctional reagent such as diacid, dianhydride, diepoxy, etc. 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 randomly or block copolymerized and have a linear or branched structure.

The molecular weight, the MFI index, the density of these polyolefins can also vary to a large extent, which those skilled in the art will appreciate. MFI, short for Melt Flow Index, is the Melt Flow Index. It is measured according to the ASTM 1238 standard.

Advantageously, the non-functionalized polyolefins (B2) are chosen from polypropylene homopolymers or copolymers and any homopolymer of ethylene or copolymer of ethylene and a comonomer of the higher alpha olefinic type 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, 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-olefin units and units carrying polar reactive functions such as epoxy, carboxylic acid or carboxylic acid anhydride functions. As examples of such polymers, mention may be made of ter-polymers of ethylene, alkyl acrylate and maleic anhydride or glycidyl methacrylate such as the Applicant's Lotader® or polyolefins grafted with maleic anhydride such as Orevac® from the company SK Chemicals as well as ter polymers of ethylene, alkyl acrylate and (meth)acrylic acid. Mention may also be made of homopolymers or copolymers polypropylene grafted with a carboxylic acid anhydride and then condensed with polyamides or monoamino polyamide oligomers.

Advantageously, said constituent composition of said sealing layer(s) is devoid of polyether block amide (PEBA). In this embodiment, the PEBAs are therefore excluded from the polyolefins.

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 steps of mixing the various polymers and of converting 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), hydroxybenzoic acid esters such as 2-ethylhexyl para-hydroxybenzoate (EHPB) and 2-decylhexyl para-hydroxybenzoate (HDPB), tetrahydrofurfuryl alcohol esters or ethers, such as oligoethyleneoxytetrahydrofurfurylalcohol, and citric acid or hydroxymalonic acid esters, such as oligoethyleneoxymalonate.

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

Another more particularly preferred plasticizer is N-(2-hydroxy-propyl)benzenesulfonamide (HP-BSA). The latter indeed 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.

In one embodiment, said composition of said at least one innermost sealing layer comprises at least one polyolefin, in a proportion of 1% to less than 15% by weight, in particular from 1% to 12% by weight, in particular from 1% to 10% by weight, relative to the total weight of the composition.

In one embodiment, said composition is devoid of plasticizer.

In one embodiment, said composition of said at least one innermost sealing layer comprises at least one polyolefin, in a proportion of 1% to less than 15% by weight, in particular from 1% to 12% by weight, in particular from 1% to 10% by weight, relative to the total weight of the composition and said composition is devoid of plasticizer In yet another embodiment, said composition of said at least one innermost sealing layer comprises at least one polyolefin, in a proportion of 1% to less than 15% by weight, in particular from 1% to 12% by weight, in particular from 1% to 10% by weight, relative to the total weight of the composition and from 0.1 to 1.5% by weight of plasticizer relative to the total weight of the composition.

Regarding the composite reinforcement layer and the P2j polymer

The polymer P2j can be a thermoplastic polymer or a thermosetting polymer. One or more layers of composite reinforcement 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 comprised 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 at 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 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, relative to the weight composition total,

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

Impact modifiers

The impact modifiers are advantageously made up of a polymer having a flexural modulus of less than 100 MPa measured according to the ISO 178 standard and a Tg of less than 0° C. (measured according to the 11357-2 standard at the level of the inflection bridge of the DSC thermogram ), in particular a polyolefin.

The polyolefin is as defined above.

The additives of said composition of the composite reinforcement layer can be chosen from an antioxidant, a heat stabilizer, a UV absorber, a light stabilizer, a lubricant, an inorganic filler, a flame retardant, a plasticizer and a dye, with the exception of a nucleating agent.

Advantageously, said composition consists of said thermoplastic polymer P2j mainly, 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 can be identical or different. In one embodiment, a single majority polymer is present at least in the composite reinforcement layer and which does not adhere to the sealing layer. In one embodiment, each reinforcement layer comprises the same type of polymer, in particular an epoxy or epoxy-based resin.

Polymer P2j

P2j Thermoplastic Polymer

Thermoplastic or thermoplastic polymer is understood to mean a material which is generally solid at ambient temperature, which may be semi-crystalline or amorphous, in particular semi-crystalline and which softens when the temperature rises, in particular after passing from its temperature of glass transition (Tg) and flows at a higher temperature when it is amorphous, or which can present a frank melting on passing its so-called melting temperature (Tf) when it is semi-crystalline, and which becomes solid again when 'a decrease in temperature below its crystallization temperature, Te, (for a semi-crystalline) and below its glass transition temperature (for an amorphous). 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 thermoplastic polymer when it corresponds to a polyamide, is preferably in a range going from 10,000 to 40,000, preferably from 10,000 to 30,000. These Mn values can correspond to inherent viscosities greater than or equal to 0.8 as determined in 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)

Examples of suitable semi-crystalline thermoplastic polymers in the present invention include: polyamides, in particular comprising an aromatic and/or cycloaliphatic structure, including copolymers, for example polyamide-polyether copolymers, polyesters, polyaryletherketones (PAEK ), polyetherether ketones (PEEK), polyetherketone ketones (PEKK), polyetherketoneetherketone ketones (PEKEKK), polyimides in particular polyetherimides (PEI) or polyamide-imides, polylsulfones (PSU) in particular polyarylsulfones such as polyphenyl sulfones (PPSU), polyether sulfones (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 (diamine in Ca) being chosen from aliphatic diamines, linear or branched, cycloaliphatic diamines and alkylaromatic diamines and the unit (diacid in Cb) being chosen from aliphatic diacids, linear or branched, cycloaliphatic diacids and aromatic diacids ;

X.T denotes a unit obtained from the polycondensation of a Cx diamine and terephthalic acid, with x representing the number of carbon atoms of the Cx diamine, x being between 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, 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, one PA 11/BACT/6T, PA 11/MPMDT/6T, PA 11/MPMDT/10T, PA 11/BACT/10T, one PA 11/MXDT/10T, one 11/5T/10T.

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

The expression "stable in transformation" means that the viscosity in the molten state does not evolve by more than 70% as a function of time, and precisely between 1 minute (time necessary to melt the product) and at least 30 minutes , in particular between 1 minute and 30 minutes. Advantageously, the melt viscosity of said composition of said innermost sealing layer is substantially constant for up to 20 minutes.

By "substantially constant" is meant that the viscosity in the molten state does not change in a proportion of more than 20% up to 20 minutes, between 1 minute and at least 5 minutes, in particular between 1 minute and 5 minutes.

Advantageously, said composition also exhibits resistance to thermo-oxidation. The expression "resistance to thermo-oxidation" is characterized by the half-life (in hours) of the materials. It corresponds to the time after which the ISO 527-2 1 BA specimens, aged in air at 140°C, lost half their initial elongation at break measured according to ISO 527-2 (2012).

Advantageously, the resistance to thermoxidation is at least 80 days, in particular 100 days.

Advantageously, said composition has a melt viscosity of approximately 13,000 to approximately 23,000 Pa.s, as determined by oscillatory rheology at 270° C. as defined above.

The melt viscosity is determined by oscillatory rheology at 270°C at 10 rad/sec under nitrogen sweep with 5% strain and a shear of 10 sec-1 on a Physica MCR301 apparatus between two parallel planes of 25 mm in diameter.

The inherent viscosity is determined according to ISO 307-2007 but in m-cresol instead of sulfuric acid, the temperature being 20°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 reinforcement layer consists of a composition comprising the same type of polymer, in particular an epoxy or epoxy-based resin.

Said composition comprising said polymer P2j can be transparent to radiation suitable for welding.

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

Regarding the structure

Said multilayer structure therefore comprises at least one sealing layer and at least one layer of composite reinforcement which is wound around the sealing 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. Nevertheless, said different polymers may be of the same type.

Thus, if one of the two composite waterproofing and reinforcement 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 comprise up to 10 layers of sealing and up to 10 layers of composite reinforcement of different natures. It is obvious that said multilayer structure is not necessarily symmetrical and that it can therefore comprise more sealing layers than composite layers or vice versa, but there cannot be an alternation of layers and reinforcement 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 of composite reinforcement.

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

Advantageously, they consist of compositions which respectively comprise different polymers.

Advantageously, they consist of compositions which respectively comprise polyamides, in particular semi-crystalline polyamides, in particular aliphatic or aromatic, and an epoxy or epoxy-based resin P2j .

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

All combinations of these two layers are therefore within the scope of the invention, provided that at least said innermost composite reinforcement 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 polyamide, in particular a semi-crystalline, in particular aliphatic, in particular long-chain or semi-aromatic, in particular long-chain polyamide. chain.

By the expression same type of polyamide, it is necessary to understand for example a polyamide which can be an identical or different polyamide according to the layers. Advantageously, said polyamide is a semi-crystalline, in particular aliphatic, in particular long-chain, polyamide or a semi-aromatic, in particular long-chain, polyamide and said polymer P2j is an epoxy or epoxy-based resin.

In a first variant, said polyamide is a semi-crystalline polyamide, in particular aliphatic, in particular long-chain, and said polymer P2j is an epoxy or epoxy-based resin.

In a second variant, said polyamide is a semi-aromatic polyamide, in particular with a long chain, and said polymer P2j is an epoxy or epoxy-based resin. Advantageously, the polyamide is identical for all the sealing layers. Advantageously, said semi-crystalline polyamide is a long-chain aliphatic polyamide, in particular PA1010, PA 1012, PA 1212, PA11, PA12, in particular PA11 or PA12. Advantageously, the polyamide is a long-chain semi-aromatic polyamide, in particular PA 11/5T, PA 11/6T or PA 11/1 OT. Obviously in this case, the Amino 11 level in the copolyamide must be chosen judiciously so that the Tm of said polymers is less than 280°C, preferably 266°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 polyamide P2j is identical for all the reinforcing layers. Advantageously, in said multilayer structure, each sealing layer consists of a composition comprising the same type of polyamide, in particular a semi-crystalline polyamide and each reinforcing layer consists of a composition comprising the same type of polymer P2j , in particular an epoxy or epoxy-based resin.

Advantageously, said polyamide is a long-chain aliphatic semi-crystalline polyamide, in particular PA1010, PA 1012, PA 1212, PA11, PA12, in particular PA 11 or PA12 and said polymer P2j is a semi-aromatic semi-crystalline polyamide, in particular chosen from a PA MPMDT/6T, a PA1 1/1 OT, a PA 1 1/BACT, a PA 5T/10T, a PA 1 1/6T/10T, a PA MXDT/10T, a PA MPMDT/10T, one PA BACT/1 OT, one PA BACT/6T, PA BACT/10T/6T, one PA 11/BACT/6T, PA 1 1/MPMDT/6T, PA 1 1/MPMDT/10T, PA 1 1/ BACT/ 1 OT, an AP and 1 1/MXDT/1 OT.

In one embodiment, said multilayer structure consists of a single reinforcing layer and a single sealing layer in which said polyamide is a long-chain aliphatic semi-crystalline 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 PA1 1/1 OT, a PA 1 1/BACT, a PA 5T/ 10T, a PA 1 1/6T/10T, a PA MXDT/10T, a PA MPMDT/10T, a PA BACT/1 OT, a PA BACT/6T, PA BACT/10T/6T, PA 1 1/BACT/6T, PA 11/MPMDT/6T, PA 11/MPMDT/1 OT,

PA 11/ BACT/10T and a PA 1 1/MXDT/10T.

In yet 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 semi-crystalline polyamide, in particular PA1010 , PA 1012, PA 1212, PA1 1 , PA12, or semi-crystalline semi-aromatic, in particular chosen from polyamide 1 1/5T or 1 1/6T or 1 1/1 OT, MXDT/10T, MPMDT /10T and BACT/10T, in particular PA 11 or PA12 and said polymer P2j is an epoxy or epoxy-based resin.

Advantageously, said multilayer structure further comprises at least one outer layer consisting of a fibrous material of continuous fiberglass impregnated with a transparent amorphous polymer, said layer being the outermost layer of said multilayer structure.

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

Regarding the fibrous material

As regards the fibers forming said fibrous material, these are in particular fibers of mineral, organic or plant origin.

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

Said fibrous material may therefore comprise up to 3.5% by weight of a material of organic nature (thermosetting or thermoplastic resin type) called size.

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 higher than the Tg of the polymer or mixture of thermoplastic polymer constituting the pre-impregnation matrix when the latter is amorphous, or higher than the Tm polymer or mixture of thermoplastic polymer constituting the pre-impregnation matrix when the latter is semi-crystalline. Advantageously, they are based on a semi-crystalline thermoplastic polymer and have a melting point Tf higher than the Tg of the polymer or thermoplastic polymer mixture constituting the pre-impregnation matrix when the latter is amorphous, or higher than the Tm polymer or mixture of thermoplastic polymer constituting the pre-impregnation matrix when the latter is semi-crystalline. Thus, there is no risk of fusion for the organic fibers of constitution fibrous material during impregnation by 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, sisal, and other cellulosic fibers, in particular viscose. These fibers of plant origin can be used pure, treated or even coated with a coating layer, in order to facilitate adhesion and impregnation of the thermoplastic polymer matrix.

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

It can also match fibers with holding threads.

These building 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 form the pre-impregnated fibrous material.

Organic fiber rovings can have several grammages. They may also have several geometries. The fibers making up the fibrous material may also be in the form of a mixture of these reinforcing fibers of different geometries. The fibers are continuous fibers.

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

It is used in the form of a wick or several wicks.

According to another aspect, the present invention relates to a method for 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 or by half-shell injection.

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

All the characteristics detailed above also apply to the process.

Brief description of figures.

EXAMPLES

In all the examples, the tanks are obtained by rotational molding of the sealing layer (liner) at a temperature adapted to the nature of the thermoplastic resin used.

Examples:

Products used

The polyamide used is Rilsan®PA11 (BESNO marketed by the company Arkema), the thermal stabilizer is ANOX® NDB TL89: organic stabilizer of the phenol phosphite type marketed by the company Chemtura. The carbodiimide used is Stabiliser® 9000 (Poly-(1,3,5-triisopropylphenylene-2,4-carbodiimide) marketed by the company Raschig.

The catalyst used is H3PO3 or H3PO4.

BBSA: n-butyl benzene sulfonamide marketed by the company PROVIRON

EXXELOR VA 1801: polyolefin (copolymer of ethylene - propylene functionalized maleic anhydride) marketed by Exxon.

Example 1: Evaluation of the compositions of the invention: Viscosity in the molten state and Thermal resistance at 140°C.

The proportions indicated are percentages by weight relative to the total weight of the composition.

Test on twin screws (Coperion ZSK40 having two screws with a diameter of 40mm and a length corresponding to 40 times its diameter) at 280°C - 300 rpm under vacuum - 600 mm/hg at 60 kg/h. The PA base is dried (<0.1% humidity)

The compositions of the invention and comparisons are shown in Table 1

[Table 1 ]

Example 2: Comparison of the properties of the compositions according to the invention with the comparative composition 1

Liners in PA1 1 with the comparative composition 1 and comparative 2 and the compositions of the invention 1 and 2 were prepared by rotational molding.

The permeability to hydrogen is determined according to the following protocol: it consists of sweeping the upper face of the film with the test gas (Hydrogen) and measuring by gas phase chromatography the flux which diffuses through the film in the part lower, swept by the carrier gas: Nitrogen

The experimental conditions are shown in Table 2 and the results are shown in Table 3:

[Table 2]

[Table 3]

The results in Table 3 show a lower hydrogen permeability of the liners prepared from the compositions of the invention (Inv 1 and Inv 2).

Example 3: Notched Charpy impact at -30°C according to ISO 179-1:2010

The same liners as for example 2 were prepared by rotational molding.

These liners have been notched Charpy impact tested at -30°C. Notched Charpy impact results are presented in Table 4.

[Table 4]

The cold resistance of PA11 liners without plasticizer or with 1.5% plasticizer is superior to those of PA11 liner with 6% plasticizer or 12% plasticizer.

Claims

26 CLAIMS

1 . Multilayer structure intended for the storage of hydrogen, comprising, from the inside outwards, at least one sealing layer (1) and at least one composite reinforcement layer (2), the said outermost composite reinforcement layer innermost layer being wrapped around said outermost adjacent sealing layer (1), at least said innermost sealing layer consisting of a composition comprising, relative to the total weight of the composition: a. 20.5 to 99.845% by weight of at least one polyamide; b. 0.005 to 0.5% by weight of at least one catalyst; vs. 0.05 to 1% by weight of at least one heat stabilizer; d. 0.1 to 3% by weight of at least one oligo- or poly-carbodiimide; e. 0 to 1.5% by weight of at least one plasticizer; f. 0 to less than 15% by weight of at least one polyolefin, in particular from 1 to less than 15% by weight; g. 0 to 30% of at least one additive. and at least one of said composite reinforcement layers consisting of a fibrous material in the form of continuous fibers impregnated with a composition mainly comprising at least one polymer P2j, j=1 to m, m being the number of reinforcement layers , in particular an epoxy or epoxy-based resin

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 or epoxy-based resin.

4. Multilayer structure according to one of claims 2 or 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 resin or based on epoxy.

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. Tl Multilayer structure according to one of Claims 1 to 5, characterized in that the said polyamide of the innermost sealing layer 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 1 1/6T or 1 1/1 OT, MXDT/10T, MPMDT/10T and BACT/10T. Multilayer structure according to one of Claims 1 to 6, characterized in that the said polymer P2j is an epoxy or epoxy-based resin. Multilayer structure according to one of Claims 6 or 7, characterized in that the said multilayer structure consists of a single reinforcing layer and a single sealing layer in which the said 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 1 1/1 OT, MXDT/10T, MPMDT/10T and BACT/ 10T, in particular PA 11 or PA12 and said polymer P2j is an epoxy or epoxy-based resin. Multilayer structure according to one of Claims 1 to 8, characterized in that the said viscosity in the molten state of the said composition of the said innermost sealing layer is substantially constant up to 20 minutes, Multilayer structure according to one of Claims 1 to 9, characterized in that the said composition of the said innermost sealing layer also exhibits resistance to thermo-oxidation. Multilayer structure according to one of Claims 1 to 10, characterized in that the said composition of the said innermost sealing layer has a melt viscosity of 13,000 to 23,000 Pa.s, as determined by oscillatory rheology at 270°C, at 10 rad/sec under nitrogen sweep with 5% deformation and a shear of 10 sec-1 between two parallel planes 25 mm in diameter. Multilayer structure according to one of Claims 1 to 11, characterized in that the fibrous material of the composite reinforcing layer is chosen from glass fibers, carbon fibers, basalt or basalt-based fibers, or a mixture of these, in particular carbon fibers. Multilayer structure according to one of Claims 1 to 12, characterized in that the said structure further comprises at least one outer layer consisting of a fibrous material of continuous fiberglass impregnated with a transparent amorphous polymer, the said layer being the layer outermost of said multilayer structure. Process for manufacturing a multilayer structure as defined in one of Claims 1 to 13, characterized in that it comprises a step of preparing the sealing layer by extrusion blow molding, in particular by reactive extrusion, by rotational molding, by injection or extrusion. Process for manufacturing a multilayer structure according to claim 14, characterized in that it comprises a step of filament winding the reinforcing layer as defined in claim 1 around the sealing layer as defined in claim 1.