FR3148637A1 - SINGLE-LAYER OR MULTI-LAYER STRUCTURE FOR THE TRANSPORT, STORAGE OR DISTRIBUTION OF COMPRESSED GAS - Google Patents

Abstract

The present invention relates to a single-layer or multi-layer structure for the transport, storage or distribution of compressed gas, preferably under high pressure, in particular hydrogen, comprising: at least one composite reinforcement layer constituting the envelope of said structure made of a fibrous material in the form of continuous fibers impregnated with a composition mainly comprising at least one ductile thermoplastic polymer, preferably semi-crystalline, having a glass transition temperature (Tg) measured according to the ISO 11357-3: 2013 standard, said Tg being less than or equal to the operating temperature Tu, or Tg -Tu ≥ 100°C, the impregnated fibrous material constituting said composite reinforcement layer having, after consolidation, a transverse strain at break greater than the strain at break of said fibers, in particular greater than 1.6%, in particular 1.8%, in particular 2%, more particularly 2.2%, at the operating temperature and at the deformation rate representative of use, said structure being devoid of an internal sealing layer.

Description

SINGLE-LAYER OR MULTI-LAYER STRUCTURE FOR THE TRANSPORT, STORAGE OR DISTRIBUTION OF COMPRESSED GAS

The invention relates to single-layer or multi-layer structures for the transport, storage or distribution of compressed gas, preferably under high pressure, in particular hydrogen, their use and their method of preparation.

Structures for transporting, storing or distributing compressed gas, preferably under high pressure, in particular hydrogen, using composite reinforcement to ensure pressure resistance, i.e. type III or IV tanks, all include a liner (sealing layer), metallic (type III) or polymer (type IV) to ensure gas-tightness, in particular hydrogen, because the composite layer includes porosities and microfissures which prevent it from being impermeable to gas, in particular hydrogen.

Type V tanks, i.e. composite tanks without a liner, therefore remain an interesting target today, because they are more economical (no liner to manufacture) and more efficient (higher volumetric storage efficiency) but inaccessible to date due, in particular, to the transverse microcracking of composites which appears prematurely during pressurization, particularly repeated pressurization, i.e. which appears at a pressure value equal to a fraction of the pressure in service.

Thus the solution closest to a type IV, sometimes called type 4.5, consists of making a monolithic thermoplastic or thermosetting composite tank, in which the composite is welded to the liner. To do this it may be interesting to use several layers of composite, one of which has a matrix with a melting point close to that of the polymer making up the liner, so as to limit the residual thermal stresses on the liner.

Thus, international application WO 2021/019181 describes a multilayer structure chosen from a tank, a pipe or tube, intended for the transport, distribution or storage of hydrogen, comprising, from the inside to the outside, at least one sealing layer and at least one composite reinforcement layer.

The European Union has just validated the end of thermal engines which will take effect from 2035.

One of the goals sought is to offer vehicles that are less and less polluting. Thus, electric or hybrid vehicles with 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 shocks and the external environment, which can be at extreme temperatures and variable humidity. It is also necessary to avoid any risk of flames.

In addition, each battery manufacturer designs its batteries according to a specific model, making them unsuitable for mass use independent of the chosen vehicle model. Thus, each car manufacturer must adapt to the design constraints of the batteries, and revise its models accordingly to integrate them.

In addition, it is important that its operating temperature does not exceed 55°C to avoid damaging 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.

Furthermore, the electric vehicle still suffers today from several problems, namely the autonomy of the battery, the use in these batteries of rare earths whose resources are not inexhaustible 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 using a fuel cell and thus power electric vehicles.

However, storing hydrogen is technically difficult and expensive due to its very low molar mass and very low liquefaction temperature, particularly when it comes to mobile storage. However, to be effective, storage must be carried out in small volumes, which requires maintaining the hydrogen under high pressure, given the operating temperatures of the vehicles. This is the case, in particular, for hybrid fuel cell road vehicles for which the aim is to achieve a range of around 600 to 700 km, or even less for mainly urban uses in addition to an electric base on batteries.

It is therefore necessary to reduce the production costs of compressed gas tanks, particularly hydrogen tanks, while maintaining their gas-impermeability properties, particularly hydrogen-impermeability, and having a resistance which must be sufficient to allow the tank to be used repeatedly at the service (or usage) pressure, particularly during the pressure cycling inherent in its use.

The present invention therefore relates to a single-layer or multi-layer structure, for the transport, storage or distribution of compressed gas, preferably under high pressure, in particular hydrogen, comprising:

at least one composite reinforcement layer constituting the envelope of said structure consisting of a fibrous material in the form of continuous fibers impregnated with a composition mainly comprising at least one ductile thermoplastic polymer, preferably semi-crystalline, having a glass transition temperature (Tg) measured according to the ISO 11357-3: 2013 standard, said Tg being less than or equal to the operating temperature (Tu), or Tg -Tu ≥ 100°C, for example Tg -Tu > +100°C, in particular Tg -Tu ≥ 80°C, in particular Tg -Tu ≥ 50°C,

the impregnated fibrous material making up said composite reinforcement layer having, after consolidation, a transverse strain at break greater than the strain at break of said fibers, in particular greater than 1.6%, in particular 1.8%, in particular 2%, more particularly 2.2%, at the temperature of use and at the strain rate representative of the use,

said structure being devoid of an internal sealing layer.

The inventors have therefore unexpectedly found that a structure having at least one composite reinforcement layer whose thermoplastic polymer has a Tg as defined above and whose impregnated fibrous material composing said composite reinforcement layer has, after consolidation, a transverse deformation at break, as defined above, made it possible to dispense with the presence of an internal sealing layer (liner) but to maintain in parallel its gas impermeability properties, in particular to hydrogen and to have sufficient resistance to allow the repeated use of the tank at the service (or use) pressure, in particular during the pressure cycling inherent in its use and therefore to reduce the production costs of compressed gas tanks, in particular hydrogen tanks.

The structure defined above has several advantages, including:

- to have a greater volumetric storage efficiency than a tank with an internal sealing layer (liner),

- to present a gain in weight and mass storage efficiency compared to a tank with an internal sealing layer (liner),

- to eliminate the risk of collapse (detachment) of the liner (sealing layer), existing with type IV tanks having an internal sealing layer,

- to present an economic gain linked to the elimination of the liner manufacturing and liner drying stage, and to the saving of raw materials used to manufacture the liner,

- to simplify the manufacture of the tank by using hot-laid thermoplastic prepregs (or tapes), in particular tapes comprising a high-performance matrix with a high melting point

- to facilitate the recycling of the final tank with a single type of material used (carbon fibers impregnated with a thermoplastic polymer)

- to limit the number of interfaces and therefore the risks of leaks in the tank

- to eliminate differential deformations (liner vs composite) during the manufacturing phases and therefore reduce internal residual stresses;

- to present improved fatigue resistance (i.e. pressure cycling linked to filling and emptying cycles) of the tank and therefore to increase the service life.

The composite reinforcement layer is therefore made up of at least one layer which is a consolidated fibrous material.

The term “structure” means any hollow three-dimensional structure capable of withstanding pressure, excluding any structure such as a film or a granule.

The term “structure” refers in particular to a tank, pipe or tube, comprising or consisting of one or more layers, in particular a reservoir.

The structure may be a tank, pipe or tube for mobile storage of hydrogen, 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 supplying hydrogen or on a drone for supplying hydrogen, but it may also be a tank, pipe or tube for stationary storage of hydrogen at a station for distributing hydrogen to vehicles.

The term "high pressure" means several hundred bars, in particular 100 to 900 bar (or 100,000 to 900,000 hPa, in particular 300 to 900 bar (or 300,000 to 900,000 hPa).

In one embodiment, said structure comprises or consists of a single layer.

In another embodiment, said structure comprises or consists of two layers.

The term "gas" refers to any body which is in the state of an expansive and compressible fluid (gaseous state) under conditions of temperature greater than -250°C and pressure less than 3000 bars.

The term “gas” means in particular air, helium, oxygen, nitrogen, methane, natural gas, natural gas vehicle (NGV) such as compressed natural gas (CNG) or liquefied natural gas (LNG), liquefied petroleum gas (LPG), propane, butane and hydrogen, in particular methane, natural gas, natural gas vehicle (NGV) such as compressed natural gas (CNG) or liquefied natural gas (LNG), liquefied petroleum gas (LPG), propane, butane and hydrogen, in particular hydrogen.

The expression "operating temperature Tu" means the temperature at which the said structure is used. This temperature obviously depends on the type of gas transported (or conveyed), stored or distributed and the type of use. Thus, during rapid filling, the said structure (i.e. the tank or pipe) heats up and Tu increases with the increase in pressure. During rapid emptying, the said structure cools down and Tu decreases with the drop in pressure.

The use may be the storage of gas, in particular hydrogen, in a gas refueling station, in particular hydrogen for all types of vehicles, light and heavy fleets, for the mobility, industrial activities, storage and energy markets.

It can also be the transport of hydrogen under the sea to land from an offshore wind turbine on which the electrolysis of seawater is carried out to produce green hydrogen which will then be transported to land to a storage or refueling station.

In one embodiment, the operating temperature Tu is from -80°C to +160°C.

When using the structure, the composite reinforcement must be able to withstand the deformations of said structure depending on the temperature of the compressed gas. The composite reinforcement allows the structure to withstand the internal pressure in said structure generated by the fluid transported (or conveyed), stored or distributed.

According to the course given by Professor Antoine Chateauminois at ESCPI (Composite materials course, Fracture processes in unidirectional composites (UD), Sheet 3, May 2000), Under transverse loading, the failure of a unidirectional ply involves matrix cracking and decohesion at the fiber/matrix interface. This failure mode generally corresponds to the first damage observed in cross laminates subjected to tensile forces. Transverse cracks known as intra-laminar cracks are then observed in the plies disoriented with respect to the loading axis. These failures occur well before the failure of plies oriented at 0° with respect to the stress axis.

To avoid this appearance of transverse cracks, said impregnated fibrous material making up said composite reinforcement layer constituting the envelope of said structure must therefore present, after consolidation, a transverse strain at break greater than the strain at break of said fibers, in particular greater than 1.6%, in particular 1.8%, in particular 2%, more particularly 2.2%, at the temperature of use and at the strain rate representative of the use.

In one embodiment, the operating temperature Tu is from -252.8°C to +150°C.

In one embodiment, the operating temperature Tu is between -80°C and +150°C.

The behavior of a material, such as its fragility or ductility, depends, among other things, on the deformation rate.

In one embodiment, the strain rate representative of the use is from 10 ^-5 to 10 ² s ^-1 , in particular from 10 ^-5 s ^-1 to 1s ^-1 , in particular from 10 ^-3 to 1s ^-1 .

The term "ductile" refers to the ability of a material to deform plastically without breaking.

It was therefore found that if the deformation at transverse rupture of the composite occurs after the rupture of the fibres then the problem of premature microcracking during the use of the tanks no longer exists and the use of a liner can be eliminated, this all the more easily since it is also known that before mechanical stress, a composite with a semi-crystalline thermoplastic matrix can have a very low permeability to hydrogen, if this composite is well consolidated and does not present any defects (porosity, microcracking linked to the thermal cycle of manufacture etc.)

The said structure therefore comprises a composite whose transverse mechanical properties are sufficient to avoid the phenomenon of microcracking. This resistance is sufficient to allow the repeated use of the tank at the service pressure because the structure comprises a composite which has good transverse resistance, also during the pressure cycling inherent in its use.

The evaluation of the transverse deformation at break of the said composite reinforcement layers obtained is carried out according to the ISO 527-5:2021 standard on a coupon: a 2mm thick plate, 300x 300mm, composed of a stack of 16 unidirectional UD layers of impregnated fibrous material is obtained by flat laser deposition followed by autoclave consolidation. In the plate obtained, transverse tensile test specimens were machined (T90°), the axis of the fibers being perpendicular to the axis of the test specimen and then tested at a strain rate of 10 ^-5 s ^-1 , 10 ^-3 s ^-1 , 1s ^-1 and 10 ² s ^-1 and a temperature of -252.8°C, -60°C, +23°C and +85°C.

Although the tested plate is manufactured using a process different from the manufacturing process of said structure of the invention, the transverse fracture deformation results obtained on this plate guarantee the good behavior of said structure and in particular the sealing of said structure under pressure.

The assessment of the transverse fracture strain can also be determined by other methods, for example:

- on a unidirectional composite composed of the same type of fiber and the same polymer matrix, by performing traction on this composite, perpendicular to the axis of the fibers and in particular, a strain value at break greater than that of the fibers used, preferably greater than 1.6%, in particular 1.8%, in particular 2%, more particularly 2.2%, at the temperature of use and at the strain rate representative of the use, will be sought.

- or on a laminated plate with a 0-90° orientation by applying traction in one of the two directions and in particular, the rupture of the fibres stressed in their longitudinal direction (i.e. in the direction of the deformation imposed by the tensile testing machine) must occur before that of the folds transverse to the direction of traction.

- or a laminated plate with a 0-90° orientation, in biaxial bending, consisting of punching the plate in its middle and transversely to its thickness, the plate being previously deposited on a hollow support, and in particular, in the off-axis directions of the fibers, a radial or orthoradial deformation value greater than the deformation at break of the fiber used, preferably greater than 1.6%, in particular 1.8%, in particular 2%, more particularly 2.2%, at the temperature of use and at the deformation rate representative of the use, will be sought.

- or on a laminated plate with a 0-90° orientation, in biaxial traction, by performing traction simultaneously in the 2 directions of the fibers of the plate and in particular, in the off-axis directions of the fibers, a radial or orthoradial deformation value greater than the deformation at break of the fiber used, preferably greater than 1.6%, in particular 1.8%, in particular 2%, more particularly 2.2%, at the temperature of use and at the deformation rate representative of the use, will be sought.

- or on a laminated plate with a quasi-iso orientation of 0°/+-45°/90° by applying traction in one of the 4 directions of the plate fibres and in particular, and in particular, a strain at break greater than that of the fibres used, preferably greater than 1.6%, in particular 1.8%, in particular 2%, more particularly 2.2%, at the temperature of use and at the strain rate representative of the use, will be sought.

- or on a quasi-iso laminated plate with an orientation of 0°/+-45°/90°, in biaxial bending, consisting of punching the plate in its middle and transversely to its thickness, the plate being previously deposited on a hollow support, and in particular, a value of 1.6%, in particular at 1.8%, in particular at 2%, more particularly at 2.2%, of radial or orthoradial deformation, at the operating temperature and at the deformation speed representative of the use, will then be sought.

- or in biaxial traction, on a laminated plate with a quasi-iso orientation of 0°/+-45°/90° by carrying out traction in 2 of the 4 directions of the plate fibers and in particular, a value of 1.6%, in particular at 1.8%, in particular at 2%, more particularly at 2.2%, of radial or orthoradial deformation, at the operating temperature and at the deformation speed representative of the use, will then be sought.

Tensile tests are carried out at different temperatures according to ISO 527-1:2012 on type 1BA dumbbells.

The consolidated plates have a porosity rate of less than 5%, in particular less than 2%.

The porosity rate can be determined by image analysis.

It can also be determined by determining the relative difference between the theoretical density and the experimental density (general method):

a) The required data are:

- The density of the thermoplastic matrix

- The density of the fibers

• masse linéique (g/m) par exemple pour une tape ¼ de pouce (issu d’un seul rowing)
• masse surfacique (g/m²) par exemple pour une tape plus large ou un tissu

- The weight of the reinforcement:

• linear mass (g/m) for example for a ¼ inch tape (from a single rowing)
• surface mass (g/m²) for example for a wider tape or fabric

b) Measures to be carried out:

The number of samples must be at least 30 for the result to be representative of the material studied.

The measures to be taken are:

• Longueur (si masse linéique connue).
• Longueur et largeur (si masse surfacique connue).

- The size of the samples taken:

• Length (if linear mass known).
• Length and width (if surface mass known).

• Mesures de masse dans l’air et dans l’eau.

- The experimental density of the samples taken:

• Mass measurements in air and water.

- The measurement of the fiber content is determined according to ISO 1172:1999 or by thermogravimetric analysis (TGA) as determined for example in the document B. Benzler, Applikationslabor, Mettler Toledo, Giesen, UserCom 1/2001.

The measurement of carbon fiber content can be determined according to ISO 14127:2008.

Determination of the theoretical mass fiber rate:

a) Determination of the theoretical mass fiber rate:

With

m _l the linear mass of the tape,

L the length of the sample and

Me _air the mass of the sample measured in air.

The variation in the mass rate of fibers is assumed to be directly related to a variation in the matrix rate without taking into account the variation in the quantity of fibers in the reinforcement.

b) Determination of the theoretical density:

With dm and df the respective densities of the matrix and the fibers.

The theoretical density thus calculated is the accessible density if there is no porosity in the samples.

c) Evaluation of porosity:

Porosity is then the relative difference between theoretical density and experimental density.

In one embodiment, the plasticity threshold of the ductile thermoplastic polymer impregnating the fibrous material in the form of continuous fibers is less than 70, in particular less than 60, in particular less than 50.

The plasticity threshold, denoted σ0, represents the limit between the elastic domain and the plastic domain.

When a part is stressed (when it is pulled, compressed or twisted, etc.), it begins to deform reversibly (elastic deformation), i.e. its dimensions change, but it returns to its initial shape when the stress stops. Some materials, called brittle, break in this mode of deformation if the stress is too strong.

For so-called ductile materials, a sufficient increase in stress (i.e. the stress in the material) leads to definitive deformation; when the stress stops, the part remains deformed (i.e. the stress in the material has reached the plasticity threshold of the material and therefore the triggering of an irreversible deformation process).

The plasticity threshold can be determined by tension on ISO 527-1BA specimens.

The tensile test consists of pulling on a bar, and allows the extraction of the one-dimensional stress-strain curve of the material illustrated in the figure. . We observe during a monotonically increasing load that the curve presents two phases:

First phase. It is defined by σ < σ0. The relationship between σ and ɛ is linear. If the loading has not exceeded the stress limit σ0, the discharge will go through the same path:

there is reversibility; this is the definition of elasticity. The behavior relationship is written:

σ = E.ε

where E is Young's modulus, identified as the slope of the line.

Second phase. It is characterized by σ > σ0. The material reaches the plastic domain. To observe the irreversibility linked to the plastic behavior, it is necessary to perform a discharge of the specimen. The discharge is performed from a deformation greater than the elastic deformation, ɛ _e = σ/E. At this stage of deformation, the value of the stress in the material, σ, can be equal to the initial elastic limit, σ0 and remain constant for any deformation greater than ɛ _e : we then say that the material exhibits perfectly plastic behavior. Generally this is not the case in polymers and when the strain ɛ, exceeds the elastic strain, ɛ _e , the stress in the material continues to increase beyond σ0, as the total strain ɛt increases, but according to a slope, much lower than that imposed by the elastic modulus in the elastic deformation regime: we then speak of rheohardening and the slope of the curve connecting the stresses to the strain is the tangent modulus Et and its value is much lower than that of the elastic modulus E. Conversely, during the unloading of the material which occurs when the applied strain decreases, the decrease in stress follows a straight line of slope E and thus, when the stress becomes zero, we observe that the strain is not: a residual strain is observed, this is the plastic strain. We thus identify an additive partition of the uniaxial strain into elastic and plastic parts:

ɛ= ɛ _e + ɛ _p

where ɛ _e is the elastic, reversible deformation (recoverable upon discharge), linked to the stress through the law of elasticity (σ= Eɛ _e ) and where ɛ _p the plastic, irreversible or residual deformation.

In a simple tensile test (uniaxial), the plastic deformation produces an irreversible elongation of the specimen. On the stress-strain curve, the elastic part corresponds to the linear (straight) part of the curve, the plastic domain corresponds to the inflection of this curve. The limit in terms of stress, between the two domains defines the elastic limit noted here σo (usually in metals we often speak of Re 0.2% which is the nominal stress at 0.2% of plastic deformation, i.e. a value very close to the plasticity threshold σo, but more easily measurable in practical terms).

This mechanical analysis, which applies well to metals at T < Tf/2, remains approximate in the case of polymers which are subject to marked effects of temperature and strain rate which reflect the manifestation of viscous phenomena during the deformation of the polymer. Thus, the elastic modulus and the stress at the plasticity threshold depend on the strain rate and the temperature just like the plastic deformation: we then speak of viscoplastic deformation. The partition of the deformations is expressed as follows:

ɛ= ɛ _e + ɛ _vp

and the determination of ɛ _vp can be done exactly as explained for the plastic deformation above, except that this value will have to be determined immediately when the stress becomes zero. After a certain rest time without stress, the polymer may have recovered part of this deformation: the viscoplastic deformation depends on the observation time.

Furthermore, the manifestation of these viscous deformation phenomena means that the transition from elastic behavior to plastic behavior is gradual and that the shape of the stress-strain curve presents a curvature in the plasticity threshold domain which makes it difficult to measure σo, in practice. Thus, it is usual to determine σo by the intersection between the elastic modulus and the tangent modulus. As explained above, the effect of the strain rate and the temperature mean that this value depends on the stress conditions of the polymer and this is precisely what will control the appearance or not of transverse cracking of the composite using this polymer as a matrix: when the value of σo becomes too high, due to a decreasing temperature or an increasing strain rate, the rupture occurs preferentially at the fiber & matrix interface rather than in the resin, and the resin cannot deform (visco)plastically. Conversely, when the temperature is high enough or the strain rate is low enough, the value of the plasticity threshold, σo becomes low enough for the polymer to deform (visco)plastically and rupture occurs in the resin and for high strain levels, typically greater than the strain at break of the fibers, or even greater than 1.6%, especially 1.8%, especially 2%, more particularly 2.2%.

The evaluation of the strain at break of said fibers is carried out by a tensile test on the dry fiber (or on a strand of dry fibers) (according to the ISO 527-1: 2012 standard) which makes it possible to measure its breaking stress, its modulus and its strain at break.

The 3 quantities are linked by the relation S = E x epsilon (S = breaking stress, E = modulus, epsilon = breaking strain).

In one embodiment, said structure is devoid of an external sealing layer. The expression "external sealing layer" means a sealing layer located above said composite reinforcement layer.

Regarding the excluded internal sealing layer

The excluded internal sealing layer is any sealing layer consisting of a polymer or polymer composition without fiber, regardless of the polymer or polymer composition constituting it.

Regarding the composite reinforcement layer and the thermoplastic polymer

One or more layers of composite reinforcement may be present.

Each of said layers is made up of a composition mainly comprising at least one thermoplastic polymer. The number of layers present is in particular from 1 to 10, in particular from 1 to 5, in particular from 1 to 3, preferably it is 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.

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 total weight of the composition,

Said composition impregnating the fibrous material of said composite reinforcement layer may also comprise impact modifiers and/or additives.

The additives may be selected from an antioxidant, a heat stabilizer, a UV absorber, a light stabilizer, a lubricant, an inorganic filler, a flame retardant, a nucleating agent, a plasticizer and a colorant.

Advantageously, said composition consists of said thermoplastic polymer predominantly, from 0 to 5% by weight of impact modifier, from 0 to 5% by weight of additives, the sum of the constituents of the composition being equal to 100% (based on a minimum of thermoplastic polymer of 90%).

Said at least one majority polymer of each layer may be identical or different.

In one embodiment, only one major polymer is present at least in the composite reinforcement layer.

In one embodiment, each reinforcing layer comprises the same type of polymer.

Thermoplastic polymer

Thermoplastic, or thermoplastic polymer, means a material that is generally solid at room temperature, which may be semi-crystalline or amorphous, in particular semi-crystalline, and which softens when the temperature increases, in particular after passing its glass transition temperature (Tg) and flows at a higher temperature when it is amorphous, or which may exhibit a clear melting when passing its so-called melting temperature (Tf) when it is semi-crystalline, and which becomes solid again when the temperature decreases below its crystallization temperature, Tc, (for a semi-crystalline) and below its glass transition temperature (for an amorphous).

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

The thermoplastic polymer in the composition is ductile: this means that it exhibits (visco)plastic deformation when deformed beyond its elastic deformation, ɛ _e .

The thermoplastic polymer of the composition of at least one of said composite reinforcement layers is such that its Tg is less than or equal to the operating temperature Tu,

or that Tg -Tu ≥ 100°C, for example Tg -Tu > +100°C, in particular Tg -Tu ≥ 80°C, in particular Tg -Tu ≥ 50°C.

In a first variant, the thermoplastic polymer has a Tg less than or equal to the operating temperature Tu, regardless of the position of said reinforcing layer.

In one embodiment of this first variant, said reinforcing layer consisting of a composition comprising the thermoplastic polymer having a Tg less than or equal to the operating temperature Tu is the innermost layer in contact with the compressed gas.

In another embodiment of this first variant, said reinforcing layer consisting of a composition comprising the thermoplastic polymer having a Tg less than or equal to the operating temperature Tu is the outermost reinforcing layer of the structure.

In a second variant, the thermoplastic polymer has a Tg -Tu ≥ 100°C.

In one embodiment of this second variant, said reinforcing layer consisting of a composition comprising the thermoplastic polymer having a Tg -Tu ≥ 100°C is the innermost layer in contact with the compressed gas.

In another embodiment of this second variant, said reinforcing layer consisting of a composition comprising the thermoplastic polymer having a Tg -Tu ≥ 100°C is the outermost reinforcing layer of the structure.

In a third variant, the thermoplastic polymer has a Tg -Tu ≥ 80°C.

In one embodiment of this third variant, said reinforcing layer consisting of a composition comprising the thermoplastic polymer having a Tg -Tu ≥ 80°C is the innermost layer in contact with the compressed gas.

In another embodiment of this third variant, said reinforcing layer consisting of a composition comprising the thermoplastic polymer having a Tg -Tu ≥ 80°C is the outermost reinforcing layer of the structure.

In a fourth variant, the thermoplastic polymer has a Tg -Tu ≥ 50°C.

In one embodiment of this fourth variant, said reinforcing layer consisting of a composition comprising the thermoplastic polymer having a Tg -Tu ≥ 50°C is the innermost layer in contact with the compressed gas.

In another embodiment of this fourth variant, said reinforcing layer consisting of a composition comprising the thermoplastic polymer having a Tg -Tu ≥ 100°C is the outermost reinforcing layer of the structure.

In one embodiment of these four variants, all the reinforcing layers consisting of a composition comprising the thermoplastic polymer are identical and therefore correspond to both the innermost and outermost reinforcing layers of the structure.

The number average molecular weight Mn of said thermoplastic polymer is preferably in a range from 10000 to 40000g/mol, preferably from 12000 to 30000g/mol.

The Mn are determined in particular by calculation from the rate of terminal functions determined by potentiometric titration in solution.

Mn masses can also be determined by size exclusion chromatography or NMR.

Examples of semi-crystalline thermoplastic polymers suitable for use in the present invention include:

polyamides,

polyamides-polyethers, polyesters,

polyaryletherketones (PAEK),

polyetherether ketones (PEEK),

polyetherketone ketones (PEKK),

polyetherketoneetherketone ketones (PEKEKK),

polyimides, in particular polyetherimides (PEI) or polyamide-imides,

polysulfones (PSU) in particular polyarylsulfones such as polyphenyl sulfones (PPSU),

polyethersulfones (PES).

Semi-crystalline polymers are more particularly preferred.

In one embodiment, said thermoplastic polymer is a polyamide, in particular semi-crystalline.

Polyamide

The nomenclature used to define polyamides is described in the ISO 1874-1:2011 standard "Plastics - Polyamide (PA) materials for moulding 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 may be a homopolyamide or a copolyamide or a mixture thereof.

Advantageously, the polyamide, in particular semi-crystalline, has a C/N ratio greater than or equal to 5, preferably greater than or equal to 8, in particular greater than or equal to 9, and more particularly greater than or equal to 10.

The C/N ratio means the ratio of the number of carbon atoms to the number of nitrogen atoms in the polyamide.

In the case of a PA-XY type homopolyamide, the number of carbon atoms per nitrogen atom is the average of the X unit and the Y unit.

In the case of a copolyamide, the number of carbons per nitrogen atom is calculated according to the same principle. The calculation is carried out in molar proportion to the different amide units.

The polyamide, in particular semi-crystalline, can be an aliphatic, cycloaliphatic or semi-aromatic polyamide.

In a first variant, the polyamide, in particular semi-crystalline, is an aliphatic polyamide.

Said at least one aliphatic polyamide, in particular semi-crystalline, can be obtained from the polycondensation of at least one lactam, or from the polycondensation of at least one amino acid, or from the polycondensation of at least one diamine X with at least one dicarboxylic acid Y.

When said at least one aliphatic polyamide, in particular semi-crystalline, is obtained from the polycondensation of at least one lactam, it can therefore comprise a single lactam or several lactams.

When said at least one aliphatic polyamide, in particular semi-crystalline, is obtained from the polycondensation of at least one lactam, said at least one lactam is chosen from a C6 to C18 lactam, preferably a C8 to C12 lactam, more preferably a C10 to C12 lactam.

Advantageously, said at least one aliphatic polyamide, in particular semi-crystalline, is obtained from the polycondensation of a single lactam and said lactam may be chosen in particular from caprolactam, lauryllactam and undecanolactam, advantageously lauryllactam.

When said at least one aliphatic polyamide, in particular semi-crystalline, is obtained from the polycondensation of at least one amino acid, said at least one amino acid may be chosen from a C6 to C18 amino acid, preferably a C10 to C18, more preferably a C10 to C12 amino acid.

A C6 to C12 amino acid includes, in particular, 6-aminohexanoic acid, 9-aminononanoic acid, 10-aminodecanoic acid, 10-aminoundecanoic acid, 12-aminododecanoic acid and 11-aminoundecanoic acid as well as its derivatives, in particular N-heptyl-11-aminoundecanoic acid.

When said at least one aliphatic polyamide, in particular semi-crystalline, is obtained from the polycondensation of at least one amino acid, it may comprise a single amino acid or several amino acids.

Advantageously, said aliphatic polyamide, in particular semi-crystalline, is obtained from the polycondensation of a single amino acid and said amino acid is chosen from 11-aminoundecanoic acid and 12-aminododecanoic acid, advantageously 11-aminoundecanoic acid.

When said at least one aliphatic polyamide, in particular semi-crystalline, is obtained from the polycondensation of at least one diamine X with at least one diacid Y, then the diamine is C4-C36, preferably C6-C18, preferably C6-C12, more preferably C10-C12, with at least one diacid Y in C4-C36, preferably C6-C18, preferably C6-C12, more preferably C8-C12, and said at least one diamine X is an aliphatic diamine and said at least one diacid Y is an aliphatic diacid.

The diamine can be linear or branched. Advantageously, it is linear.

Said at least one C4-C36 diamine X may in particular be chosen from 1,4-butanediamine, 1,5-pentamethylenediamine, 1,6-hexamethylenediamine, 1,7-heptamethyldiamine, 1,8-octamethyldiamine, 1,9-nonamethyldiamine, 1,10-decamethyldiamine, 1,11-undecamethyldiamine, 1,12-dodecamethyldiamine, 1,13-tridecamethyldiamine, 1,14-tetradecamethyldiamine, 1,16-heXdecamethyldiamine and 1,18-octadecamethyldiamine, octadecenediamine, eicosanediamine, docosanediamine and diamines obtained from fatty acids.

Advantageously, said at least one diamine X is C4-C18 and chosen from 1,4-butanediamine, 1,5-pentanediamine, 1,6-hexamethylenediamine, 1,7-heptamethyldiamine, 1,8-octamethyldiamine, 1,9-nonamethyldiamine, 1,10-decamethyldiamine, 1,11-undecamethyldiamine, 1,12-dodecamethyldiamine, 1,13-tridecamethyldiamine, 1,14-tetradecamethyldiamine, 1,16-heXdecamethyldiamine and 1,18-octadecamethyldiamine.

Advantageously, said at least one diamine X is C6 to C12, in particular chosen from 1,6-hexamethylenediamine, 1,7-heptamethyldiamine, 1,8-octamethyldiamine, 1,9-nonamethyldiamine, 1,10-decamethyldiamine, 1,11-undecamethyldiamine, 1,12-dodecamethyldiamine.

Advantageously, the diamine X used is C10 to C12, in particular chosen from 1,10-decamethyldiamine, 1,11-undecamethyldiamine, 1,12-dodecamethyldiamine.

Said at least one dicarboxylic acid Y is C4 to C36 and can be chosen from succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, brassylic acid, tetradecanedioic acid, pentadecanedioic acid, hexdecanedioic acid, octadecanedioic acid, and diacids obtained from fatty acids.

The diacid can be linear or branched. Advantageously, it is linear.

Advantageously, said at least one dicarboxylic acid Y is C6 to C18 and is chosen from adipic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, brassylic acid, tetradecanedioic acid, pentadecanedioic acid, hexdecanedioic acid, octadecanedioic acid.

Advantageously, said at least one dicarboxylic acid Y is C6 to C12 and is chosen from adipic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid.

Advantageously, said at least one dicarboxylic acid Y is C8 to C12 and is chosen from suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid.

In one embodiment, the polyamide, in particular semi-crystalline, impregnating the continuous fibers of the composite reinforcing layer is an aliphatic polyamide, in particular chosen from PA410, PA 56, PA59, PA510, PA512, PA513, PA 514, PA6, PA 66, PA 69, PA610, PA612, PA614, PA618, PA1010, PA1012, PApip10, PApip12, PA1014, PA1018, PA1210, PA1212, PA1214, PA1218, PA11, PA12, preferably PA 6, PA66, PA410, PA510, PA 69, PA610, PA 512, PA612, PA 514, PA614, PA618, PA PA1010, PA1012, PA1014, PA1018, PA1214, PA1218, PA11 and PA12, more preferably PA 11 or PA12, and their mixture.

Advantageously, the aliphatic polyamide, in particular semi-crystalline, is partially or totally bio-resourced.

In a second variant, the polyamide, in particular semi-crystalline, is a semi-aromatic polyamide.

By semi-aromatic polyamide is meant here a polyamide derived from monomers comprising at least one monomer with an aromatic group and at least one aliphatic or cycloaliphatic monomer.

Examples of suitable monomers containing aromatic groups are terephthalic acid (T) and its derivatives, isophthalic acid (I) and its derivatives, naphthalene dicarboxylic acid (N) and its derivatives, C6 to C20 aromatic diamines, arylamines such as p-xylylenediamine (PXD) and m-xylylenediamine (MXD).

Advantageously, suitable monomers containing aromatic groups are terephthalic acid (T), isophthalic acid (I), p-xylylenediamine (PXD) and m-xylylenediamine (MXD), BAC.

Semi-aromatic polyamides can be of type XY with X alkylaromatic diamine (or arylamine) and Y dicarboxylic acid chosen from aliphatic, linear or branched dicarboxylic acids, or X aliphatic, linear or branched diamine, and Y chosen from aromatic dicarboxylic acids.

The semi-aromatic polyamide, optionally modified by urea units, may also be 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 (Ca diamine).(Cb diacid), with a representing the number of carbon atoms of the diamine and b representing the number of carbon atoms of the diacid, a and b each being between 4 and 36, advantageously between 9 and 18, the unit (Ca diamine) being chosen from linear or branched aliphatic diamines, cycloaliphatic diamines and alkylaromatic diamines and the unit (Cb diacid) being chosen from linear or branched aliphatic diacids, cycloaliphatic diamines and alkylaromatic diamines. cycloaliphatic and aromatic diacids;

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

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

In one embodiment of this second variant, the polyamide, in particular semi-crystalline, impregnating the continuous fibers of the composite reinforcement layer is a semi-aromatic polyamide, in particular chosen from PA MPMDT/6T, PA 11/10T, PA 11/BACT, PA 5T/10T, PA 11/6T/10T, PA MXDT/4T, PA MXDT/6T, PA MXDT/10T, PA MPMDT/4T, PA MPMDT/6T, PA MPMDT/10T, PA BACT/10T, PA BACT/6T, PA BACT/4T, PA BACT/10T/6T, PA 11/BACT/4T, PA 11/BACT/6T, PA 11/BACT/10T, PA 11/MXDT/4T, PA 11/MXDT/6T, PA 11/MXDT/10T, PA 11/MPMDT/4T, PA 11/MPMDT/6T, PA 11/MPMDT/10T, PA 11/MXDT/10T, PA11/5T/10T, and their mixture.

Advantageously, the semi-aromatic polyamide, in particular semi-crystalline, is partially or totally bio-resourced.

Regarding the fibrous material before and after its impregnation

Throughout the description, the term ribbon or strip or strips of fibrous material impregnated with a thermoplastic polymer or tape may be used and means the same thing.

Concerning the fibers constituting said fibrous material, these are in particular fibers of mineral, organic or plant origin in the form of strands.

In one embodiment, the number of fibers per strand is for carbon fibers greater than or equal to 24K (i.e. 24,000 fibers per strand), in particular from 24 to 30K.

In another embodiment, the number of fibers per strand is for carbon fibers greater than 30K, in particular is greater than or equal to 50K.

Advantageously, the weight for the glass fiber is greater than or equal to 1200 Tex, in particular less than or equal to 4800 tex, in particular between 1200 and 2400 tex.

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 thermoplastic or thermosetting polymer, such as semi-aromatic polyamide fibers, aramid fibers or polyolefin fibers for example. Preferably, they are based on amorphous thermoplastic polymer and have a glass transition temperature Tg greater than the Tg of the polymer or mixture of thermoplastic polymers constituting the impregnation matrix when the latter is amorphous, or greater than the Tf of the polymer or mixture of thermoplastic polymers constituting the impregnation matrix when the latter is semi-crystalline. Advantageously, they are based on semi-crystalline thermoplastic polymer and have a melting temperature Tf higher than the Tg of the polymer or mixture of thermoplastic polymers constituting the impregnation matrix when the latter is amorphous, or higher than the Tf of the polymer or mixture of thermoplastic polymers constituting the impregnation matrix when the latter is semi-crystalline. Thus, there is no risk of melting for the organic fibers constituting the 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, silk, in particular spider silk, sisal, and other cellulosic fibers, in particular viscose. These fibers of plant origin can be used pure, treated or coated with a coating layer, in order to facilitate the adhesion and impregnation of the thermoplastic polymer matrix.

It can also match fibers with holding wires.

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

Organic fiber wicks can have several weights. They can also have several geometries.

The fibers are in the form of continuous fibers, which make up 2D fabrics, nonwovens (NCF), braids or rovings of unidirectional fibers (UD) or nonwovens. The fibers constituting the fibrous material can also be in the form of a mixture of these reinforcing fibers of different geometries.

Preferably the fibrous material is selected from glass fibers, carbon fibers, basalt fibers and basalt-based fibers.

Advantageously, it is used in the form of a wick or several wicks.

In order to improve the physicochemical links between polymer and fibers, fiber manufacturers use sizes whose composition and rate can vary. However, being generally of an organic nature (thermosetting or thermoplastic resin type) and very often formulated for the impregnation of fibers with low melting point polymers or thermosetting polymers with low Tg point, the sizes are often degraded by the impregnation processes, in particular during the pre-impregnation stages (melted route, passage in solvent solution, etc.) and/or during the melting stages of the thermoplastic matrix, in particular when it has a high melting point (for a semi-crystalline or a high Tg (for an amorphous or thermosetting material). In addition, the chemical compatibility between the matrix polymer and the size is not always optimal; the resulting adhesion force can be modified in a positive or negative way compared to that observed with an unsized fiber.

However, sizing is essential or unavoidable in some cases. An unsized fiber is difficult to handle. In fact, sizing not only plays the role of promoting adhesion of the matrix to the fiber; but it also serves as a protector and binder for carbon or glass fibrils, for example, in order to handle them without breaking them.

In impregnated materials also called "ready-to-use", the impregnating polymer or mixture of thermoplastic polymers is distributed uniformly and homogeneously around the fibers. In this type of material, the impregnating thermoplastic polymer must be distributed as homogeneously as possible within the fibers in order to obtain a minimum of porosities, i.e. a minimum of voids between the fibers. Indeed, the presence of porosities in this type of material can act as stress concentration points, during mechanical tensile stress for example, and which then form rupture initiation points of the impregnated fibrous material and mechanically weaken it. A homogeneous distribution of the polymer or mixture of polymers therefore improves the mechanical strength and homogeneity of the composite material formed from these impregnated fibrous materials.

In a first embodiment, the fiber content in said impregnated fibrous material is from 30 to 65% by volume, in particular from 45 to 65% by volume, preferably from 50 to 60% by volume, in particular from 52 to 60% by volume, in particular from 53 to 57% by volume.

The measurement of the fibre content is determined according to ISO 1172:1999 or by thermogravimetric analysis (TGA) as determined for example in B. Benzler, Applikationslabor, Mettler Toledo, Giesen, UserCom 1/2001.

The measurement of carbon fiber content can be determined according to ISO 14127:2008.

In a second embodiment, the fiber content in said impregnated fibrous material is from 30 to 50% by volume, in particular from 30 to 40% by volume.

The measurement of the impregnation rate can be carried out by image analysis (using a microscope or a camera or digital camera, in particular), of a cross-section of the ribbon, by dividing the surface of the ribbon impregnated by the polymer by the total surface of the product (impregnated surface plus surface of the porosity). In order to obtain a good quality image, it is preferable to coat the ribbon cut in its transverse direction in a standard polishing resin and to polish with a standard protocol allowing the observation of the sample under a microscope at a magnification of at least 6 times.

Advantageously, the porosity rate of said impregnated fibrous material is less than 5%, in particular less than 2%.

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

The porosity rate corresponds to the closed porosity rate and can be determined either by electron microscopy or as the relative deviation between the theoretical density and the experimental density of said impregnated fibrous material as described above.

In all cases the porosity rate is an average rate over a significant volume of fibrous materials, i.e. over a volume greater than or equal to that of a 500m reel of tape with an average width of 12.7mm (1/2 inch) and 140µm thick.

Regarding the single-layer or multi-layer structure

The structure can be single-layer or multi-layer.

Single layer structure

According to one embodiment, the structure is single-layer and comprises at least one composite reinforcement layer as defined above.

In a first variant, said structure is single-layer and consists of a single layer of composite reinforcement as defined above, to the exclusion of any other composite or non-composite layer.

Said reinforcing layer may consist of one or more layers.

In one embodiment of this first variant, said single-layer structure is characterized in that the fiber content by volume of said composite reinforcement layer is from 50 to 60% by volume, in particular from 53 to 57% by volume.

Advantageously, the operating temperature in this embodiment of this first variant is higher than ambient temperature.

In another embodiment of this first variant, said single-layer structure is characterized in that the fiber content by volume of said composite reinforcement layer is from 30 to 50% by volume, in particular from 30 to 40% by volume.

Advantageously, the operating temperature in this embodiment of this first variant is less than -252.8°C at atmospheric pressure.

Advantageously, in this variant and these embodiments, the thermoplastic polymer of the composition impregnating the fibrous material is an aliphatic polyamide, in particular semi-crystalline, in particular chosen from PA410, PA 56, PA59, PA510, PA512, PA513, PA 514, PA6, PA 66, PA 69, PA610, PA612, PA614, PA618, PA1010, PA1012, PApip10, PApip12, PA1014, PA1018, PA1210, PA1212, PA1214, PA1218, PA11, PA12, preferably PA 6, PA66, PA410, PA510, PA 69, PA610, PA 512, PA612, PA 514, PA614, PA618, PA PA1010, PA1012, PA1014, PA1018, PA1214, PA1218, PA11 and PA12, more preferably PA 11 or PA12, and their mixture.

Advantageously, the fibrous material present in the composite reinforcement layer in the single-layer structure as defined above is chosen from glass fibers, carbon fibers, basalt or basalt-based fibers.

In one embodiment, said single-layer structure defined above comprises one or more injection-molded inserts made of semi-crystalline thermoplastic polymer, preferably aliphatic.

Multi-layer structure

In a second variant, said structure is multi-layered and comprises at least the following two successive layers, from the inside to the outside:

- at least one composite reinforcement layer as defined above, said composite reinforcement layer being in contact with the compressed gas,

- at least one external layer of composite reinforcement consisting of a fibrous material in the form of continuous fibers impregnated with a composition mainly comprising at least one thermoplastic polymer, preferably semi-crystalline,

said composite reinforcement layer and said external composite reinforcement layer being different,

said outermost composite reinforcement layer being welded to the innermost composite reinforcement outer layer.

The impregnated fibrous material making up said external composite reinforcement layer having, after consolidation, a transverse deformation at break identical to or different from that of the impregnated fibrous material making up said composite reinforcement layer after consolidation.

The thermoplastic polymer of said external composite reinforcement layer is as defined for the composite reinforcement layer (and therefore internal).

It is obvious that the thermoplastic polymer of said composite reinforcement layer and the thermoplastic polymer of said external composite reinforcement layer are different. By "different" it is meant that either the two polymers are of different nature, for example one polymer which is a PEI and the other chosen from polyaryletherketones (PAEK), polyetheretherketones (PEEK) and polyetherketoneketones (PEKK), in particular polyetheretherketones (PEEK), or the two polymers are of the same nature, for example the two polymers are polyamide but one is aliphatic and the other is semi-aromatic, but these two polymers are compatible i.e. partially or totally miscible or able to react with each other, or the two polymers are two different aliphatic polyamides or two different semi-aromatic polyamides or the fibrous material is different by its nature and/or by the number of fibers in the fibrous material.

Said composition impregnating the fibrous material of said external composite reinforcement layer may also comprise impact modifiers and/or additives.

The additives may be selected from an antioxidant, a heat stabilizer, a UV absorber, a light stabilizer, a lubricant, an inorganic filler, a flame retardant, a nucleating agent, a plasticizer and a colorant.

Advantageously, said composition impregnating the fibrous material of said external composite reinforcement layer consists of said thermoplastic polymer predominantly, from 0 to 5% by weight of impact modifier, from 0 to 5% by weight of additives, the sum of the constituents of the composition being equal to 100% (based on a minimum of thermoplastic polymer of 90%).

Said compositions impregnating the fibrous material of said composite reinforcing layer and the fibrous material of said external composite reinforcing layer are different.

In one embodiment, the thermoplastic polymer impregnating the continuous fibers of the composite reinforcing layer of said multilayer structure defined above is an aliphatic polyamide, in particular chosen from PA410, PA 56, PA59, PA510, PA512, PA513, PA 514, PA6, PA 66, PA 69, PA610, PA612, PA614, PA618, PA1010, PA1012, PApip10, PApip12, PA1014, PA1018, PA1210, PA1212, PA1214, PA1218, PA11, PA12, preferably PA 6, PA66, PA410, PA510, PA 69, PA610, PA 512, PA612, PA 514, PA614, PA618, PA PA1010, PA1012, PA1014, PA1018, PA1214, PA1218, PA11 and PA12, more preferably PA 11 or PA12, and their mixture.

In a first variant of this embodiment, the thermoplastic polymer impregnating the continuous fibers of the external composite reinforcement layer is an aliphatic polyamide, in particular chosen from PA410, PA 56, PA59, PA510, PA512, PA513, PA 514, PA6, PA 66, PA 69, PA610, PA612, PA614, PA618, PA1010, PA1012, PApip10, PApip12, PA1014, PA1018, PA1210, PA1212, PA1214, PA1218, PA11, PA12, preferably PA 6, PA66, PA410, PA510, PA 69, PA610, PA 512, PA612, PA 514, PA614, PA618, PA PA1010, PA1012, PA1014, PA1018, PA1214, PA1218, PA11 and PA12, more preferably PA 11 or PA12, and their mixture, and different from the thermoplastic polymer impregnating the continuous fibers of the composite reinforcement layer.

In a second variant of this embodiment, the thermoplastic polymer impregnating the continuous fibers of the external composite reinforcement layer is a semi-aromatic polyamide, in particular chosen from PA MPMDT/6T, PA 11/10T, PA 11/BACT, PA 5T/10T, PA 11/6T/10T, PA MXDT/4T, PA MXDT/6T, PA MXDT/10T, PA MPMDT/4T, PA MPMDT/6T, PA MPMDT/10T, PA BACT/10T, PA BACT/6T, PA BACT/4T, PA BACT/10T/6T, PA 11/BACT/4T, PA 11/BACT/6T, PA 11/BACT/10T, PA 11/MXDT/4T, PA 11/MXDT/6T, PA 11/MXDT/10T, PA 11/MPMDT/4T, PA 11/MPMDT/6T, PA 11/MPMDT/10T, PA 11/MXDT/10T, PA11/5T/10T, and their mixture.

In another embodiment, the thermoplastic polymer impregnating the continuous fibers of the composite reinforcing layer of said multilayer structure defined above is a semi-aromatic polyamide, in particular chosen from PA MPMDT/6T, PA 11/10T, PA 11/BACT, PA 5T/10T, PA 11/6T/10T, PA MXDT/4T, PA MXDT/6T, PA MXDT/10T, PA MPMDT/4T, PA MPMDT/6T, PA MPMDT/10T, PA BACT/10T, PA BACT/6T, PA BACT/4T, PA BACT/10T/6T, PA 11/BACT/4T, PA 11/BACT/6T, PA 11/BACT/10T, PA 11/MXDT/4T, PA 11/MXDT/6T, PA 11/MXDT/10T, PA 11/MPMDT/4T, PA 11/MPMDT/6T, PA 11/MPMDT/10T, PA 11/MXDT/10T, PA11/5T/10T, and their mixture.

In a first variant of this other embodiment, the thermoplastic polymer impregnating the continuous fibers of the external composite reinforcement layer is an aliphatic polyamide, in particular chosen from PA410, PA 56, PA59, PA510, PA512, PA513, PA 514, PA6, PA 66, PA 69, PA610, PA612, PA614, PA618, PA1010, PA1012, PApip10, PApip12, PA1014, PA1018, PA1210, PA1212, PA1214, PA1218, PA11, PA12, preferably PA 6, PA66, PA410, PA510, PA 69, PA610, PA 512, PA612, PA 514, PA614, PA618, PA PA1010, PA1012, PA1014, PA1018, PA1214, PA1218, PA11 and PA12, more preferably PA 11 or PA12, and their mixture, and different from the thermoplastic polymer impregnating the continuous fibers of the composite reinforcement layer.

In a second variant of this other embodiment, the thermoplastic polymer impregnating the continuous fibers of the external composite reinforcement layer is a semi-aromatic polyamide, in particular chosen from PA MPMDT/6T, PA 11/10T, PA 11/BACT, PA 5T/10T, PA 11/6T/10T, PA MXDT/4T, PA MXDT/6T, PA MXDT/10T, PA MPMDT/4T, PA MPMDT/6T, PA MPMDT/10T, PA BACT/10T, PA BACT/6T, PA BACT/4T, PA BACT/10T/6T, PA 11/BACT/4T, PA 11/BACT/6T, PA 11/BACT/10T, PA 11/MXDT/4T, PA 11/MXDT/6T, PA 11/MXDT/10T, PA 11/MPMDT/4T, PA 11/MPMDT/6T, PA 11/MPMDT/10T, PA 11/MXDT/10T, PA11/5T/10T, and their mixture.

In yet another embodiment, in the multilayer structure defined above, the composite reinforcing layer has a thickness of between 1 and 30%, more particularly a thickness of between 1 and 10%, even more preferably of between 1 and 5% relative to the total thickness of the layers of the structure .

In yet another embodiment, in the multilayer structure defined above, the volume fiber content of the composite reinforcement layer is from 30 to 50%, in particular from 30 to 40%.

In yet another embodiment, in the multilayer structure defined above, the volume fiber content of the external composite reinforcement layer is from 50 to 60%, in particular from 53 to 60% by volume, in particular from 53 to 57% by volume.

In yet another embodiment, in the multilayer structure defined above, the volume fiber content of the composite reinforcement layer is from 30 to 50%, in particular from 30 to 40%, and the volume fiber content of the external composite reinforcement layer is from 50 to 60%, in particular from 53 to 60% by volume, in particular from 53 to 57% by volume.

Advantageously, the fibrous material present in the composite reinforcement layer and in the external composite reinforcement layer in the multilayer structure as defined above is chosen from glass fibers, carbon fibers, basalt or basalt-based fibers.

In one embodiment, said multilayer structure defined above comprises one or more injection-molded inserts made of semi-crystalline thermoplastic polymer, preferably aliphatic.

In one embodiment, said multilayer structure consists of two layers.

In another embodiment, said multilayer structure further comprises at least one other layer consisting of a composition mainly comprising at least one thermoplastic polymer, preferably semi-crystalline, and located above the last external layer of composite reinforcement.

Advantageously, said thermoplastic polymer is a polyamide, in particular semi-crystalline.

In particular, said polyamide is chosen from an aliphatic polyamide and a semi-aromatic polyamide.

Advantageously, the fibers of the composite reinforcement layer are of higher strength than the fibers of the outer composite reinforcement layer.

In one embodiment, the fibers of the outer composite reinforcement layer are fibers greater than 30K.

In another embodiment, the fibers of the composite reinforcing layer are fibers less than or equal to 30K.

In yet another embodiment, the fibers of the outer composite reinforcement layer are fibers greater than 30K and the fibers of the composite reinforcement layer are fibers less than or equal to 30K.

In one embodiment, said multilayer structure consists of three layers.

In yet another embodiment, said multilayer structure comprises at least four layers:

at least one composite reinforcement layer constituting the envelope of said structure as defined above,

at least one external layer of composite reinforcement consisting of a fibrous material in the form of continuous fibers impregnated with a composition mainly comprising at least one thermoplastic polymer, preferably semi-crystalline,

said composite reinforcement layer and said external composite reinforcement layer being different,

said outermost composite reinforcement layer being welded to the innermost composite reinforcement outer layer,

at least one second external layer of composite reinforcement consisting of a fibrous material in the form of continuous fibers impregnated with a composition mainly comprising at least one thermoplastic polymer, preferably semi-crystalline,

said composite reinforcement layer and said external composite reinforcement layer being different,

said second external layer of composite reinforcement being welded to the first external layer of composite reinforcement,

at least a fourth layer consisting of a composition mainly comprising at least one thermoplastic polymer, preferably semi-crystalline, and located above the last external layer of the second composite reinforcement layer.

In one embodiment, the fibers of the composite reinforcing layer are fibers less than or equal to 30K.

In another embodiment, the fibers of the first outer layer of composite reinforcement are fibers less than or equal to 30K.

In yet another embodiment, the fibers of the second outer layer of composite reinforcement are fibers greater than 30K.

In yet another embodiment, the fibers of the composite reinforcing layer are fibers less than or equal to 30K and the fibers of the first composite reinforcing layer are fibers less than or equal to 30K.

In yet another embodiment, the fibers of the composite reinforcement layer are fibers less than or equal to 30K and the fibers of the second outer composite reinforcement layer are fibers greater than 30K.

In yet another embodiment, the fibers of the composite reinforcement layer are fibers less than or equal to 30K, the fibers of the first composite reinforcement layer are fibers less than or equal to 30K, and the fibers of the second outer composite reinforcement layer are fibers greater than 30K.

In one embodiment, said multilayer structure consists of four layers.

Advantageously, said thermoplastic polymer of the first layer is a polyamide, in particular semi-crystalline.

In particular, said polyamide of the first layer is chosen from an aliphatic polyamide and a semi-aromatic polyamide, in particular an aliphatic polyamide.

Advantageously, said thermoplastic polymer of the second layer is a polyamide, in particular semi-crystalline.

In particular, said polyamide of the second is chosen from an aliphatic polyamide and a semi-aromatic polyamide, in particular a semi-aromatic polyamide.

Advantageously, said thermoplastic polymer of the third layer is a polyamide, in particular semi-crystalline.

In particular, said polyamide of the third is chosen from an aliphatic polyamide and a semi-aromatic polyamide, in particular a semi-aromatic polyamide.

Advantageously, said thermoplastic polymer of the fourth layer is a polyamide, in particular semi-crystalline.

In particular, said polyamide is chosen from an aliphatic polyamide and a semi-aromatic polyamide.

According to another aspect, the present invention relates to a method for manufacturing the single-layer or multi-layer structure as defined above, characterized in that it comprises at least one step of selecting a composite reinforcement layer constituting the envelope of said structure, said composite reinforcement layer being made of a fibrous material in the form of continuous fibers impregnated with a composition mainly comprising at least one ductile thermoplastic polymer, preferably semi-crystalline, the impregnated fibrous material having, after consolidation, a transverse strain at break greater than the strain at break of said fibers, in particular greater than 1.6%, in particular 1.8%, in particular 2%, more particularly 2.2%, at the temperature of use and at the strain rate representative of the use

The step of selecting said composite reinforcement layer may comprise the following steps:

- Selection of a ductile thermoplastic polymer (or thermoplastic polymer resin),

- Impregnation of a fibrous material with said ductile resin by one of the methods well known to those skilled in the art, to produce unidirectional (UD) ribbons or bands or tapes,

- Preparation of the composite reinforcement layer from the above ribbons or bands or tapes,

- Evaluation of the deformation at transverse rupture of said composite reinforcement layer obtained,

- Evaluation of the deformation at transverse rupture of the fibrous material (or fibers) before impregnation,

- Selection of said composite reinforcement layer having a transverse deformation greater than the deformation at break of said fibers, in particular greater than 1.6%, in particular 1.8%, in particular 2%, more particularly 2.2% at the temperature of use and at the deformation rate representative of the use.

The selection of a ductile polymer resin can be done by determining the plasticity threshold which can be carried out by traction on ISO 527-1BA test pieces.

The polymer resin considered suitable for producing a ductile composite, i.e. having a transverse deformation greater than 1.6%, in particular 1.8%, in particular 2%, more particularly 2.2% at the temperature or at the deformation rate representative of the use of said composite, is selected if its plasticity threshold is less than 70, in particular less than 60, in particular less than 50 at the temperature or at the deformation rate representative of the use of said composite.

The preparation of the composite reinforcement layer can be done in particular by filament winding, from unidirectional (UD) tapes deposited in successive layers on a mandrel which can be heated, with one or more orientation angles relative to the axis of the mandrel.

The evaluation of the transverse fracture deformation of said composite reinforcement layer obtained is carried out as described above.

The evaluation of the transverse fracture strain of the fibrous material (or fibers) before impregnation is carried out as described above.

Said composite reinforcement layer having a transverse strain at break greater than the strain at break of said fibers, in particular greater than 1.6%, in particular 1.8%, in particular 2%, more particularly 2.2%, at the temperature of use and at the strain rate representative of the use is then selected.

In one embodiment, said method comprises, after said selection step, a step of filament winding said impregnated fibrous material.

In another embodiment, said method comprises, after the filament winding step, a step of welding the external composite reinforcement layer, as defined above, onto said composite reinforcement layer.

The outer reinforcing layer is wrapped over the outermost layer of the composite reinforcing layer and is welded thereto by heating using a heating system as described in international application WO22167757.

According to another aspect, the present invention relates to the use of at least one composite reinforcement layer consisting of a fibrous material in the form of continuous fibers impregnated with a composition mainly comprising at least one thermoplastic polymer, preferably semi-crystalline, having a glass transition temperature (Tg) measured according to the ISO 11357-3: 2013 standard, said Tg being less than or equal to the operating temperature Tu, or Tg -Tu ≥ 100°C, for example Tg -Tu > +100°C, in particular Tg -Tu ≥ 80°C, in particular Tg -Tu ≥ 50°C,

said composite reinforcement layer having, after consolidation, a transverse strain at break greater than the strain at break of said fibers, in particular greater than 1.6%, in particular 1.8%, in particular 2%, more particularly 2.2% at the temperature of use and at the strain rate representative of the use, as defined above,

to constitute the envelope of a single-layer or multi-layer structure for the transport, storage or distribution of compressed gas, preferably under high pressure, in particular hydrogen.

According to yet another aspect, the present invention relates to the use of the single-layer or multi-layer structure, as defined above, for the transport, storage or distribution of compressed gas, preferably under high pressure, in particular hydrogen.

Description of the figure

There shows the traction curve obtained on a polyamide 11, this test being interrupted in the plastic domain: we illustrate the method of determining the elastic deformation ε _e and plastic deformation ε _p as well as that of the plasticity threshold.

EXAMPLES

In all examples, the measurement of the carbon fiber rate by volume is determined by image analysis (using a microscope or a camera or digital camera, in particular), of a cross section of the ribbon, by dividing the surface of the ribbon impregnated by the polymer by the total surface of the product (impregnated surface plus surface of the porosity). In order to obtain a good quality image, it is preferable to coat the ribbon cut in its transverse direction in a standard polishing resin and to polish with a standard protocol allowing the observation of the sample under a microscope at a magnification of at least 6 times.

Selection of ductile matrix

Several resin compositions (PA 11/BACT/10T and PA11) were synthesized by polycondensation and then injected using techniques well known to those skilled in the art to make ISO 527-1BA tensile test specimens.

The selection of a ductile polymer resin was carried out by determining the plasticity threshold which was determined by traction on these test pieces. The polymer resin allowing to obtain a ductile composite and was selected when its plasticity threshold is less than 70 at the temperature and the deformation rate representative of the use.

Selected compositions:

PA 11/BACT/10T (Tg 140°C measured in DSC according to ISO 11357 -3: 2013) with a plasticity threshold of less than 70.

PA11 (Tg 50°C measured in DSC according to ISO 11357 -3: 2013) with a plasticity threshold of less than 70.

Composite reinforcement layers were then prepared, after selection of the ductile matrix, from a fibrous material previously impregnated with the thermoplastic resin (tape) according to WO2018/234436 (according to modified example 2: strip of fibrous material (or tape) with a Hyosung H2550 carbon fiber impregnated with PA 11/BACT/10T (Arkema) or PA11 (Arkema)).

BAC stands for bis(aminomethyl)cyclohexane and T stands for terephthalic acid.

The composite reinforcement layers were prepared by depositing the above tape prepared by filament winding using a robot with 1500W infrared heating at a speed of 12m/min on a mandrel.

The evaluation of the transverse deformation at break of the said composite reinforcement layers obtained is carried out on a coupon: a 2 mm thick plate, 300 x 300 mm, composed of a stack of 16 unidirectional (UD) layers of impregnated fibrous material is obtained by flat laser deposition followed by autoclave consolidation. In the plate obtained, transverse tensile test specimens were machined (T90 °), the axis of the fibers being perpendicular to the axis of the test specimen and then tested at a deformation rate of 10 ^-3 s ^-1 and a temperature of -252.8 ° C, -60 ° C, +23 ° C and +85 ° C.

Said composite reinforcement layer having a transverse strain at break greater than the strain at break of said fibers, in particular greater than 1.6%, in particular 1.8%, in particular 2%, more particularly 2.2%, at the temperature of use and at the strain rate representative of the use is then selected.

The PA 11 composite with a fiber content of 55% by volume was selected for temperatures of +23°C and +85°C.

The PA 11 composite with a fiber content of 45% by volume was selected for the temperature of - 60°C.

The PA 11 composite with a fiber content of 35% by volume was selected for temperatures of -252.8°C and -60°C.

The 11/BACT/10T composite with a fiber content of 40% by volume was selected for the temperature of +85°C.

The following tanks were then prepared by filament winding on a mandrel:

Example 1: Composite monolithic tank, obtained by stacking a single type of composite layer with a ductile PA11 matrix and a carbon fiber content of 55% by volume.

The tank is used at room temperature (RT) and T > RT.

It is tested under increasing pressure and no leaks are detected before reaching the burst pressure.

Example 2: Composite monolithic tank, with a single layer of ductile PA11 matrix composite and a carbon fiber content of 45% by volume, the tank being used at -60°C and T> -60°C.

Example 3

Composite monolithic tank consisting of two layers, a composite reinforcement layer (11/BACT/10T) with a low fiber content (40% by volume) to avoid microcracks, and an external composite reinforcement layer (11/BACT/10T) with a high fiber content to achieve mechanical properties (55% by volume).

The tank is used at +85°C and T> +85°C.

Example 4:

Composite monolithic tank consisting of two layers, a composite reinforcement layer (PA11) with a low fiber content (35% by volume) to avoid microcracks, and an external composite reinforcement layer (PA11) with a high fiber content to achieve mechanical properties (55% by volume).

The tank is used from – 252.8°C to T> - 252.8°C

Example 5:

Composite monolithic tank consisting of two layers, a composite reinforcement layer (PA11) with a low fiber content (45% by volume) to avoid microcracks, and an external composite reinforcement layer (PA11/BACT/10T) with a high fiber content to achieve mechanical properties (55% by volume).

The tank is used from - 60°C to T> - 60°C.

Determinations of the presence of microcracks for the tanks of examples 1 to 5.

The presence of microcracks was determined by detecting a leak before reaching the operating pressure or while maintaining the operating pressure according to the following protocol:

Detection of possible leaks by means of a pressure test under water when pressurizing the tank to the operating pressure and/or while maintaining the pressure at the operating pressure.

All prepared tanks show no leaks and therefore no microcracks.

Claims (19)

Single-layer or multi-layer structure, for the transport, storage or distribution of compressed gas, preferably under high pressure, in particular hydrogen, comprising:
at least one composite reinforcement layer constituting the envelope of said structure consisting of a fibrous material in the form of continuous fibers impregnated with a composition mainly comprising at least one ductile thermoplastic polymer, preferably semi-crystalline, having a glass transition temperature (Tg) measured according to standard ISO 11357-3: 2013, said Tg being less than or equal to the operating temperature Tu, or Tg -Tu ≥ +100°C,
the impregnated fibrous material making up said composite reinforcement layer having, after consolidation, a transverse strain at break greater than the strain at break of said fibers, in particular greater than 1.6%, in particular 1.8%, in particular 2%, more particularly 2.2%, at the temperature of use and at the strain rate representative of the use,
said structure being devoid of an internal sealing layer. Single-layer or multi-layer structure according to claim 1, characterized in that said thermoplastic polymer of the composite reinforcing layer is a polyamide, in particular semi-crystalline, having a C/N ratio greater than or equal to 5, preferably greater than or equal to 8, in particular greater than or equal to 9, and more particularly greater than or equal to 10. Single-layer or multi-layer structure according to claim 2, characterized in that the polyamide, in particular semi-crystalline, impregnating the continuous fibers of the composite reinforcing layer is an aliphatic polyamide, in particular chosen from PA410, PA 56, PA59, PA510, PA512, PA513, PA 514, PA6, PA 66, PA 69, PA610, PA612, PA614, PA618, PA1010, PA1012, PApip10, PApip12, PA1014, PA1018, PA1210, PA1212, PA1214, PA1218, PA11, PA12, preferably PA 6, PA66, PA410, PA510, PA 69, PA610, PA 512, PA612, PA 514, PA614, PA618, PA PA1010, PA1012, PA1014, PA1018, PA1214, PA1218, PA11 and PA12, more preferably PA 11 or PA12, and their mixture. Single-layer or multi-layer structure according to claim 2, characterized in that the polyamide, in particular semi-crystalline, impregnating the continuous fibers of the composite reinforcing layer is a semi-aromatic polyamide, in particular chosen from PA MPMDT/6T, PA 11/10T, PA 11/BACT, PA 5T/10T, PA 11/6T/10T, PA MXDT/4T, PA MXDT/6T, PA MXDT/10T, PA MPMDT/4T, PA MPMDT/6T, PA MPMDT/10T, PA BACT/10T, PA BACT/6T, PA BACT/4T, PA BACT/10T/6T, PA 11/BACT/4T, PA 11/BACT/6T, PA 11/BACT/10T, PA 11/MXDT/4T, PA 11/MXDT/6T, PA 11/MXDT/10T, PA 11/MPMDT/4T, PA 11/MPMDT/6T, PA 11/MPMDT/10T, PA 11/MXDT/10T, PA11/5T/10T, and their mixture. Single-layer or multi-layer structure according to one of claims 1 to 4, characterized in that it is single-layer and comprises at least one composite reinforcement layer as defined in claim 1. Single-layer structure according to claim 5, characterized in that the fiber content by volume of said at least one composite reinforcement layer is from 30 to 50% by volume, in particular from 30 to 40% by volume. Single-layer or multi-layer structure according to one of claims 1 to 4, characterized in that it is multi-layer and comprises at least the following two successive layers, from the inside to the outside:
- at least one composite reinforcing layer as defined in claim 1, said composite reinforcing layer being in contact with the compressed gas,
- at least one external layer of composite reinforcement consisting of a fibrous material in the form of continuous fibers impregnated with a composition mainly comprising at least one thermoplastic polymer, preferably semi-crystalline,
said composite reinforcement layer and said external composite reinforcement layer being different,
said outermost composite reinforcement layer being welded to the innermost composite reinforcement outer layer. Multilayer structure according to claim 7, characterized in that the thermoplastic polymer impregnating the continuous fibers of the composite reinforcing layer is as defined in claim 3. Multilayer structure according to claim 8, characterized in that the thermoplastic polymer impregnating the continuous fibers of the external composite reinforcement layer is as defined in claim 3 and different from the thermoplastic polymer impregnating the continuous fibers of the composite reinforcement layer. Multilayer structure according to claim 8, characterized in that the thermoplastic polymer impregnating the continuous fibers of the external composite reinforcement layer is as defined in claim 4. Multilayer structure according to claim 7, characterized in that the thermoplastic polymer impregnating the continuous fibers of the composite reinforcing layer is as defined in claim 4. Multilayer structure according to claim 11, characterized in that the thermoplastic polymer impregnating the continuous fibers of the external composite reinforcement layer is as defined in claim 3. Multilayer structure according to claim 11, characterized in that the thermoplastic polymer impregnating the continuous fibers of the external composite reinforcement layer is as defined in claim 4. Multilayer structure according to one of claims 7 to 13, characterized in that the composite reinforcement layer has a thickness of between 1 and 30%, more particularly a thickness of between 1 and 10%, even more preferably of between 1 and 5% relative to the total thickness of the layers of the structure. Single-layer or multi-layer structure according to one of claims 1 to 14, characterized in that it comprises one or more injection-molded inserts, made of semi-crystalline thermoplastic polymer, preferably aliphatic. Method for manufacturing the single-layer or multi-layer structure as defined in one of claims 1 to 15, characterized in that it comprises at least one step of selecting a composite reinforcement layer constituting the envelope of said structure, said composite reinforcement layer being made of a fibrous material in the form of continuous fibers impregnated with a composition mainly comprising at least one ductile thermoplastic polymer, preferably semi-crystalline, the impregnated fibrous material having, after consolidation, a transverse strain at break greater than the strain at break of said fibers, in particular greater than 1.6%, in particular 1.8%, in particular 2%, more particularly 2.2%, at the temperature of use and at the strain rate representative of the use. Method according to claim 16, characterized in that it comprises, after said selection step, a step of filament winding of said fibrous material. Use of at least one composite reinforcement layer consisting of a fibrous material in the form of continuous fibers impregnated with a composition mainly comprising at least one thermoplastic polymer, preferably semi-crystalline, having a glass transition temperature (Tg) measured according to standard ISO 11357-3: 2013, said Tg being less than or equal to the operating temperature Tu, or Tg -Tu ≥ 100°C,
said composite reinforcement layer having, after consolidation, a transverse strain at break greater than the strain at break of said fibers, in particular greater than 1.6%, in particular 1.8%, in particular 2%, more particularly 2.2% at the temperature of use and at the strain rate representative of the use, as defined above,
to constitute the envelope of a single-layer or multi-layer structure for the transport, storage or distribution of compressed gas, preferably under high pressure, in particular hydrogen. Use of the single-layer or multi-layer structure, as defined in any one of claims 1 to 15, for the transport, storage or distribution of compressed gas, preferably under high pressure, in particular hydrogen.