Polyamide-based blow molding compositions and their uses

Abstract

The present invention relates to a blow molding or extrusion composition, in particular a blow molding composition, comprising by weight: a) 88 to 99.95%, in particular 89 to 99.9%, in particular 93 to 99.9%, of at least one semi-crystalline aliphatic polyamide having a carbon-to-nitrogen ratio greater than or equal to 7, in particular greater than or equal to 8; b) 0.05% to 10%, in particular 0.1 to 9%, in particular 0.1 to 5% by weight, of at least one branching agent selected from polyepoxys, polyanhydrides, and polyisocyanates, in particular maleic polyanhydrides and polyepoxys; c) 0 to 2% of at least one additive, in particular 0.1 to 2%, the composition having, after compounding, a melt viscosity of 10 000 to 300,000 Pa.s, preferably from 15,000 to 220,000 Pa.s, as measured in plane-plane geometry according to ISO 6721-10:2015 at a temperature of 250°C, a frequency of 0.292 rad / s and a strain of 2%, the sum of constituents a) + b) + c) making 100% by weight.

Description

Title of the invention: BLOW-MOLDED COMPOSITIONS BASED ON BRANCHED POLYAMIDES AND THEIR USES Technical field

[0001] The present invention relates to blow-molding or extrusion compositions, in particular blow-molding compositions, based on branched polyamide and their use for the preparation of single-layer or multi-layer tubular structures intended for the transport, distribution or storage of hydrogen and the process for preparing said structures. Prior art

[0002] One of the goals sought in the automotive field 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 impacts and the external environment, which may be at extreme temperatures and variable humidity. It is also necessary to avoid any risk of flames.

[0003] Furthermore, 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.

[0004] 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.

[0005] 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.

[0006] Nevertheless, the storage of hydrogen is technically difficult and expensive due to its very low molar mass and its very low liquefaction temperature, particularly when it comes to mobile storage. However, to be effective, storage must be carried out in a small volume, which requires maintaining the hydrogen under high pressure, taking into account the operating temperatures of the vehicles. This is the case, in particular, for hybrid road vehicles with fuel cells for which the aim is to achieve a autonomy of around 600 to 700 km, or even less for mainly urban uses in addition to an electric base on batteries.

[0007] Hydrogen tanks are generally made of a metal liner which must prevent the permeation of hydrogen. This first liner must itself be protected by a second liner (generally made of composite materials) designed to withstand the internal pressure of the tank (for example, 700 bars) and resist possible shocks or heat sources. The valve system must also be safe.

[0008] Application EP 0495363 relates to polyamide compositions based on a polyamide alloy (PA) and special olefin-acid anhydride copolymers and their use for the production of shaped hollow bodies.

[0009] However, the exemplified compositions are too fluid to allow extrusion of large reservoirs.

[0010] These structures are also based on polyamide 6 (PA 6) (poor resistance to zinc chloride and fragile when cold) and are therefore not compatible with reservoir applications for automotive fluids such as hydrogen.

[0011] International application WO20027031 relates to a composition based on polyamide 6 (PA6), impact modifier and metal halide.

[0012] As above, these structures are based on PA 6 (poor resistance to zinc chloride and fragile when cold) and are therefore not compatible with reservoir applications for automotive fluids such as hydrogen.

[0013] Application FR2996556 relates to a liner for the storage of gas, in particular compressed natural gas (CNG), methane or hydrogen comprising a composition based on branched polyamide and impact modifier.

[0014] The compositions exemplified are based on PA6 and therefore present the same problems as above. In addition, the compositions contain too much impact modifier which creates a risk of cavitation (blistering).

[0015] Application CA3101967 relates to polyamide compositions for blow molding based on PA 6 and impact modifier and consequently, they present the same problems as above.

[0016] It is therefore necessary to provide compositions which overcome the problems presented above and the present invention therefore relates to a blow-molding or extrusion composition, in particular blow-molding, comprising by weight:

[0017] a) from 88 to 99.95%, in particular from 89 to 99.9%, in particular from 93 to 99.9% of at least one semi-crystalline aliphatic polyamide having a number of carbons per nitrogen atom greater than or equal to 7, in particular greater than or equal to 8,

[0018] b) from 0.05% to 10%, in particular from 0.1 to 9%, in particular from 0.1 to 5% by weight of at least one branching agent chosen from polyepoxy, polyanhydrides and poly- isocyanates, in particular maleic polyanhydrides and polyepoxy,

[0019] c) from 0 to 2% of at least one additive, in particular from 0.1 to 2%,

[0020] the composition having, after compounding, a viscosity in the molten state of from 10,000 to 300,000 Pa.s, preferably from 15,000 to 220,000 Pa.s, as measured in plane-plane geometry according to standard 6721-10:2015 at a temperature of 250°C, a frequency of 0.292 rad / s and a deformation of 2%,

[0021] the sum of the constituents a) + b) + c) being 100% by weight.

[0022] The inventors have therefore unexpectedly found that the use of particular semi-crystalline aliphatic polyamides with a particular range of branching agent and the presence or absence of additives makes it possible to obtain compositions which, after compounding, have a viscosity in the molten state in a range allowing extrusion-blowing or extrusion, in particular extrusion-blowing for the constitution of a single-layer or multi-layer tubular structure intended for the transport, distribution or storage of hydrogen.

[0023] Another advantage of the compositions of the invention is good dimensional stability, i.e. low water uptake and good resistance to zinc chloride.

[0024] By “single-layer or multi-layer tubular structure” is meant a tank comprising or consisting of one or more layers.

[0025] The single-layer or multi-layer structure in the present invention also designates a pipe or tube intended for transporting hydrogen to the tank or from the tank to the fuel cell and which comprises or consists of one or more layers.

[0026] In one embodiment, non-functionalized impact modifiers are excluded from said composition.

[0027] In another embodiment, non-functionalized impact modifiers and low-functionalized impact modifiers are excluded from said composition.

[0028] By low-functionalized impact modifier is meant an impact modifier having an equivalent weight per reactive function greater than 10,000 g / mol, advantageously greater than 6000 g / mol.

[0029] In yet another embodiment, functionalized or non-functionalized impact modifiers are excluded from said composition.

[0030] In yet another embodiment, non-functionalized elastomers are excluded from said composition.

[0031] In yet another embodiment, plasticizers are excluded from said composition.

[0032] Regarding the optionally excluded shock modifier

[0033] By the expression "impact modifier" is meant a polymer of lower modulus to that of the resin, presenting good adhesion with the matrix, so as to dissipate the cracking energy.

[0034] The impact modifier is advantageously constituted by a polymer having a flexural modulus of less than 100 MPa measured according to the ISO 178 standard and a Tg of less than 0°C (measured according to the 11357-2 standard at the inflection point of the DSC thermogram), in particular a polyolefin.

[0035] The polyolefin of the impact modifier may 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 (B) and functionalized polyolefins (B1) and non-functionalized polyolefins (B2) have been described below.

[0036] 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, mention may be made of:

[0037] - homopolymers and copolymers of polyethylene, in particular LDPE, HDPE, LLDPE (linear low density polyethylene), VLDPE (very low density polyethylene) and metallocene polyethylene.

[0038] - homopolymers or copolymers of propylene.

[0039] - ethylene / alpha-olefin copolymers such as ethylene / propylene, EPRs (short for ethylene-propylene-rubber) and ethylene / propylene / diene (EPDM).

[0040] - styrene / ethylene-butene / styrene (SEBS) block copolymers, styrene / butadiene / styrene (SBS), styrene / isoprene / styrene (SIS), styrene / ethylene-propylene / styrene (SEPS).

[0041] - copolymers of ethylene with at least one product chosen from salts or esters of unsaturated carboxylic acids such as alkyl (meth)acrylate (e.g. methyl acrylate), or vinyl esters of saturated carboxylic acids such as vinyl acetate (EVA), the proportion of comonomer being up to 40% by weight.

[0042] The functionalized polyolefin (B1) may 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 terpolymerized by unsaturated epoxides such as glycidyl (meth)acrylate, or by carboxylic acids or the corresponding salts or esters such as (meth)acrylic acid (the latter being able to be neutralized totally or partially by metals such as Zn, etc.) or even by carboxylic acid anhydrides such as maleic anhydride. A functionalized polyolefin is for example a PE / EPR blend, the weight ratio of which can vary in large measurements, for example from 40 / 60 to 90 / 10, said mixture being co-grafted with an anhydride, in particular maleic anhydride, according to a grafting rate for example of 0.01 to 5% by weight, advantageously of 2.8 to 5% by weight.

[0043] The functionalized polyolefin (Bl) can be chosen from the following (co)polymers, grafted with maleic anhydride or glycidyl methacrylate, in which the grafting rate is for example from 0.01 to 5% by weight:

[0044] - PE, PP, copolymers of ethylene with propylene, butene, hexene, or octene containing for example from 35 to 80% by weight of ethylene;

[0045] - ethylene / alpha-olefin copolymers such as ethylene / propylene, EPR (short for ethylene-propylene-rubber) and ethylene / propylene / diene rubber (EPDM).

[0046] - styrene / ethylene-butene / styrene (SEBS) block copolymers, styrene / butadiene / styrene (SBS), styrene / isoprene / styrene (SIS), styrene / ethylene-propylene / styrene (SEPS).

[0047] - ethylene and vinyl acetate (EVA) copolymers, containing up to 40% in vinyl acetate weight;

[0048] - ethylene and alkyl (meth)acrylate copolymers, containing up to 40% in weight of alkyl (meth)acrylate;

[0049] - ethylene and vinyl acetate (EVA) and alkyl (meth)acrylate copolymers, containing up to 40% by weight of comonomers.

[0050] The functionalized polyolefin (Bl) can also be chosen from ethylene / propylene copolymers with a majority of propylene grafted with maleic anhydride then condensed with mono-amine polyamide (or a polyamide oligomer) (products described in EP-A-0342066).

[0051] The functionalized polyolefin (B 1) may also be a co- or terpolymer 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.

[0052] As examples of functionalized polyolefins of the latter type, the following copolymers may be mentioned, where ethylene preferably represents at least 60% by weight and where the ter monomer (the function) represents, for example, from 0.1 to 13% by weight of the copolymer:

[0053] - ethylene / alkyl (meth)acrylate / (meth)acrylic acid copolymers or maleic anhydride or glycidyl methacrylate;

[0054] - ethylene / vinyl acetate / maleic anhydride or methacrylate copolymers glycidyl;

[0055] - ethylene / vinyl acetate or alkyl (meth)acrylate / acid copolymers (meth)acrylic or maleic anhydride or glycidyl methacrylate.

[0056] In the above copolymers, (meth)acrylic acid can be salified with Zn or Li.

[0057] The term "alkyl (meth)acrylate" in (B1) or (B2) denotes C1 to C8 alkyl methacrylates and acrylates, and may be selected from methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, methyl methacrylate and ethyl methacrylate.

[0058] Furthermore, the aforementioned polyolefins (B 1) can also be crosslinked by any suitable 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 them or mixtures of at least two functionalized polyolefins capable of reacting with each other.

[0059] The above-mentioned copolymers, (B1) and (B2), can be copolymerized in a random or block manner and have a linear or branched structure.

[0060] The molecular weight, the MFI index, the density of these polyolefins can also vary to a large extent, which the person skilled in the art will appreciate. MFI, abbreviation of Melt Flow Index, is the melt flow index. It is measured according to the ASTM 1238 or ISO 1133:2011 standard.

[0061] Advantageously, the non-functionalized polyolefins (B2) are chosen from homopolymers or copolymers of polypropylene and any homopolymer of ethylene or copolymer of ethylene and a comonomer of higher alpha olefin type such as butene, hexene, octene or 4-methyl 1-pentene. Examples that may be mentioned are 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.

[0062] Advantageously, the functionalized polyolefins (B1) are chosen from any polymer comprising alpha olefinic units and units carrying polar reactive functions such as epoxy, carboxylic acid or carboxylic acid anhydride functions. Examples of such polymers include terpolymers of ethylene, alkyl acrylate and maleic anhydride or glycidyl methacrylate such as Lotader® from SK global Chemical or polyolefins grafted with maleic anhydride such as Orevac® from SK global Chemical as well as terpolymers of ethylene, alkyl acrylate and (meth)acrylic acid. Homopolymers or copolymers of polypropylene grafted with a carboxylic acid anhydride and then condensed with polyamides or monoamine oligomers of polyamide.

[0063] With regard to semi-crystalline aliphatic polyamide

[0064] The blow-molding or extrusion composition, in particular blow-molding, comprises from 88 to 99.95%, in particular from 89 to 99.8% of at least one semi-crystalline aliphatic polyamide having a number of carbons per nitrogen atom greater than or equal to 7, in particular greater than or equal to 8.

[0065] The nomenclature used to define polyamides is described in the ISO 1874-1:2011 standard "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.

[0066] The polyamide may be a homopolyamide or a copolyamide or a mixture thereof.

[0067] The expression “semi-crystalline”, within the meaning of the invention, designates a (co)polyamide which has a melting temperature (Tf) in DSC according to the ISO 11357-3:2013 standard, and an enthalpy of crystallization during the cooling step at a rate of 20K / min in DSC measured according to the ISO 11357-3:2013 standard of greater than 20 J / g, preferably greater than 30 J / g.

[0068] Said semi-crystalline aliphatic polyamide is derived from a repeating unit obtained by polycondensation:

[0069] of at least one amino acid in C9 to C18, preferably in C10 to C18, more preferably in C10 to C12, or

[0070] of at least one C9 to C18 lactam, preferably C10 to C18, more preferably C10 to C12, or

[0071] of at least one diamine Ca in C4-C36, preferably C6-C18, preferably C6-C12, more preferably C10-C12, with at least one dicarboxylic acid Cb in C4-C36, preferably C6-C18, preferably C6-C12, more preferably C10-C12,

[0072] or a mixture thereof,

[0073] provided that the number of carbon atoms per nitrogen atom of the repeating unit is greater than or equal to 7, in particular greater than or equal to 8.

[0074] A C9 to C18 amino acid is in particular 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.

[0075] A C9 to C18 lactam is notably lauryllactam.

[0076] Said at least one diamine Ca in C4-C36 may in particular be chosen from 1,4-butanediamine, 1,5-pentamethylenediamine, 1,6-hexamethylenediamine, 1,7-heptamethylenediamine, 1,8-octamethylenediamine, 1,9-nonamethylenediamine, 1,10-decamethylenediamine, 1,11-undecamethylenediamine, 1,12-dodecamethylenediamine, 1,13-tridecamethylenediamine, 1,14-tetradecamethylenediamine, 1,16-hexadecamethylenediamine and 1,18-octadecamethylenediamine, octadecenediamine, reicosanediamine, docosanediamine and diamines obtained from fatty acids.

[0077] Advantageously, said at least one diamine Ca is C6-C18 and chosen from 1,6-hexamethylenediamine, 1,7-heptamethylenediamine, 1,8-octamethylenediamine, 1,9-nonamethylenediamine, 1,10-decamethylenediamine, 1,11-undecamethylenediamine, 1,12-dodecamethylenediamine, 1,13-tridecamethylenediamine, 1,14-tetradecamethylenediamine, 1,16-hexadecamethylenediamine and 1,18-octadecamethylenediamine.

[0078] Said at least one Cb to C36 dicarboxylic acid may 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, hexadecanedioic acid, octadecanedioic acid, octadecenediamine, eicosanediamine, docosanediamine and diamines obtained from fatty acids.

[0079] Advantageously, said at least one dicarboxylic acid Cb 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, hexadecanedioic acid, octadecanedioic acid.

[0080] In one embodiment, said semi-crystalline aliphatic polyamide is chosen from PA610, PA612, PA 614, PA 10, PA11 and PA 12, in particular PA610, PA612 and PAU.

[0081] In one embodiment, said semi-crystalline aliphatic polyamide is a mixture of two semi-crystalline aliphatic polyamides having a number of carbons per nitrogen atom greater than or equal to 7, in particular greater than or equal to 8, in a weight proportion range of 5 / 95 to 95 / 5.

[0082] Advantageously, the polyamide has a concentration at the end of the amine chains of between 5 and 60 peq / g, very advantageously between 10 and 50 peq / g.

[0083] Advantageously, the polyamide has a concentration at the end of acid chains of from 5 to 60 peq / g, very advantageously of 10 to 50 peq / g.

[0084] The ends of amine chains are measured according to the following method: a sample of polyamide is dissolved in metacresol. Then, this sample is measured by potentiometry using a 0.02N perchloric acid solution.

[0085] The acid chain ends are measured according to the following method. A sample of polyamide is dissolved in benzyl alcohol. Then, this sample is measured by potentiometry with a 0.02N tetrabutylammonium hydroxide solution. Regarding the branching agent

[0086] The branching agent is present in the composition from 0.05% to 10%, in particular from 0.1 to 9%, in particular from 0.1 to 5% by weight and is chosen from polyepoxy, polyanhydrides, and polyisocyanates, in particular maleic polyanhydrides and polyepoxy.

[0087] In one embodiment, the branching agent is present in the composition from 0.1 to 2% by weight.

[0088] The branching agent may be an impact modifier, in particular a functionalized polyolefin or one other than an impact modifier.

[0089] Advantageously, it is different from the shock modifier. That is to say, it has a Tg greater than -30°C, very advantageously greater than 0°C.

[0090] Advantageously, the equivalent weight per reactive function of the branching agent is from 100 to 10,000 g / mol, advantageously from 120 to 6000 g / mol, more advantageously from 140 to 3300 g / mol.

[0091] In one embodiment, said branching agent has an average functionality in epoxy, anhydride or isocyanate functions of between 1.8 and 200, preferably between 2.1 and 150.

[0092] In yet another embodiment, the molar mass of the branching agents is from 300 to 120,000 g / mol, preferably from 400 to 100,000 g / mol.

[0093] Polyepoxys may be copolymers made from glycidyl maleic anhydride (GMA) or any other monomer comprising an epoxy function.

[0094] Examples of commercial polyepoxy are, for example, Xibond® 920 marketed by Polyscope or Joncryl® ADR 4400 marketed by BASF or lotader® AX 8900 marketed by SK Chemical.

[0095] The polyanhydrides may be copolymers comprising a copolymerized or grafted anhydride, such as maleic anhydride or itaconic anhydride.

[0096] In particular, the polyanhydrides are maleic polyanhydrides.

[0097] The other monomer of the copolymers comprising a copolymerized anhydride may be a vinyl aromatic monomer, such as styrene or styrenes in which the aromatic ring contains a halogen or an alkyl substituent.

[0098] In one embodiment, the other monomer of the copolymers comprising a copolymerized anhydride may be a vinyl monomer, such as ethylene or octadecene.

[0099] In particular, maleic polyanhydrides are copolymers of styrene and maleic anhydride.

[0100] Examples of commercial maleic polyanhydrides are, for example, Xibond® 125 (copolymer of styrene and maleic anhydride) marketed by Polyscope or Orevac IM 800 marketed by SK Chemicals or PA 18 (copolymer of 1-octadecene and maleic anhydride) marketed by Chevron Phillips Chemical Company.

[0101] The polyisocyanates are preferably oligomers of isocyanates such as isocyanurates or allophanates.

[0102] Examples of commercial polyisocyanates are, for example, Desmodur 3300 marketed by Covestro. Regarding the additive

[0103] The additives may be present up to 2% by weight relative to the total weight of the composition, in particular they are present from 0.1 to 2% by weight relative to the total weight of the composition.

[0104] The additive may be selected from a catalyst, an antioxidant, a heat stabilizer, a UV stabilizer, a light stabilizer, a lubricant, a flame retardant, a nucleating agent, a chain extender and a colorant.

[0105] In one embodiment, the additive is selected from a catalyst, an antioxidant, a heat stabilizer, a UV stabilizer, a light stabilizer, a lubricant, a flame retardant, a chain extender and a colorant.

[0106] The term "catalyst" designates a polycondensation catalyst such as a mineral or organic acid.

[0107] Advantageously, the proportion by weight of catalyst is from approximately 50 ppm to approximately 5000 ppm, in particular from approximately 100 to approximately 3300 ppm relative to the total weight of the composition.

[0108] Advantageously, the catalyst is chosen from phosphoric acid (H3PO4), phosphorous acid (H3PO3), hypophosphorous acid (H3PO2), or a mixture thereof.

[0109] The antioxidant may in particular be an antioxidant based on a copper complex of 0.05 to 5% by weight, preferably of 0.05 to 1% by weight, preferably of 0.1 to 1%.

[0110] The expression copper complex designates in particular a complex between a monovalent or divalent copper salt with an organic or inorganic acid and an organic ligand.

[0111] Advantageously, the copper salt is chosen from cupric salts (Cu(II)) of hydrogen halide, cuprous salts (Cu(I)) of hydrogen halide and salts of aliphatic carboxylic acids.

[0112] In particular, the copper salts are chosen from CuCl, CuBr, Cul, CuCN, CuC12, Cu(OAc)2, cupric stearate.

[0113] Copper complexes are notably described in US3505285.

[0114] Said copper-based complex may further comprise a ligand chosen from: phosphines, in particular triphenylphosphines, mercaptobenzimidazole, EDTA, acetylacetonate, glycine, ethylene diamine, oxalate, diethylene diamine, triethylene tetraamine, pyridine, tetrabromobisphenyl-A, tetrabisphenyl-A derivatives, such as epoxy derivatives, and derivatives of

[0115] chloro dimethanedibenzo(a,e)cyclooctene and mixtures thereof.diphosphone and dipyridyl or mixtures thereof, in particular triphenylphosphine and / or mercaptoben-zimidazole.

[0116] Phosphines refer to alkylphosphines, such as tributylphosphine or arylphosphines such as triphenylphosphine (TPP).

[0117] Advantageously, said ligand is triphenylphosphine.

[0118] Examples of complexes and their preparation are described in patent CA 02347258.

[0119] Advantageously, the quantity of copper in the composition of the invention is from 10 ppm to 1000 ppm by weight, in particular from 20 ppm to 70 ppm, in particular from 50 to 150 ppm relative to the total weight of the composition.

[0120] Advantageously, said copper-based complex further comprises a halogenated organic compound.

[0121] The halogenated organic compound may be any halogenated organic compound.

[0122] Advantageously, said halogenated organic compound is a bromine-based compound and / or an aromatic compound.

[0123] Advantageously, said aromatic compound is in particular chosen from decabro-mediphenyl, decabromodiphenyl ether, oligomers of bromo or chloro styrene, polydibromostyrene,

[0124] Advantageously, said halogenated organic compound is a bromine-based compound.

[0125] Said halogenated organic compound is added to the composition in a proportion of 50 to 30,000 ppm by weight of halogen relative to the total weight of the composition, in particular from 100 to 10,000, in particular from 500 to 1,500 ppm.

[0126] Advantageously, the copper:halogen molar ratio is from 1:1 to 1:3000, in particular from 1:2 to 1:100.

[0127] In particular, said ratio is from 1:1.5 to 1:15.

[0128] Advantageously, the antioxidant based on copper complex.

[0129] The thermal stabilizer may 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 irganox 245 or 1098 or 1010 from the company Ciba), a secondary antioxidant of the phosphite type.

[0130] The UV stabilizer can be a HALS, which means Hindered Amine Light Stabilizer or an anti-UV (for example Tinuvin 312 from the company Ciba).

[0131] The light stabilizer may be of the hindered amine type (for example Tinuvin 770 from Ciba), a phenolic or phosphorus-based stabilizer.

[0132] The lubricant may be a fatty acid type lubricant such as stearic acid.

[0133] The flame retardant may be a halogen-free flame retardant, such as described in US 2008 / 0274355 and in particular a phosphorus-based flame retardant, for example a metal salt chosen from a metal salt of phosphinic acid, in particular dialkyl phosphinate salts, in particular diethylphosphinate aluminum salt or aluminum diethylphosphinate, a metal salt of di-phosphinic acid, a mixture of flame retardant based on aluminum phosphinate and a nitrogen synergist or a mixture of flame retardant based on aluminum phosphinate and a phosphorus synergist, a polymer containing at least one metal salt of phosphinic acid, in particular on an ammonium base such as an ammonium polyphosphate, sulfamate or pentaborate,or melamine-based such as melamine, melamine salts, melamine pyrophosphates and melamine cyanurates, or cyanuric acid-based, or a polymer containing at least one metal salt of diphosphinic acid or red phosphorus, an antimony oxide, a zinc oxide, an iron oxide, a magnesium oxide or metal borates such as a zinc borate, or phosphazene, a phospham or a phosphoxynitride or a mixture thereof. They may also be halogenated flame retardants such as a brominated or polybrominated polystyrene, a brominated polycarbonate or a brominated phenol.

[0134] The nucleating agent may be silica, alumina, clay or talc, particularly talc.

[0135] Examples of suitable chain regulators are monoamines, monocarboxylic acids, diamines, triamines, dicarboxylic acids, tricarboxylic acids, tetraamines, tetracarboxylic acids and oligoamines or oligocarboxylic acids having in each case 5 to 8 amino or carboxy groups respectively and in particular dicarboxylic acids, tricarboxylic acids or a mixture of dicarboxylic acids and tricarboxylic acids. By way of example, it is possible to use dodecanedicarboxylic acid in the form of dicarboxylic acid and trimellitic acid as tricarboxylic acid. With regard to the composition

[0136] Throughout the description, all percentages are given by weight.

[0137] The blow-molding or extrusion composition, in particular blow-molding, comprises by weight:

[0138] a) from 88 to 99.95%, in particular from 89 to 99.9%, in particular from 93 to 99.9% of at least one semi-crystalline aliphatic polyamide having a number of carbons per nitrogen atom greater than or equal to 7, in particular greater than or equal to 8,

[0139] b) from 0.05% to 10%, in particular from 0.1 to 9%, in particular from 0.1 to 5% by weight of at least at least one branching agent chosen from polyepoxy, polyanhydrides, and polyisocyanates, in particular maleic polyanhydrides and polyepoxy.

[0140] c) from 0 to 2% of at least one additive, in particular from 0.1 to 2%,

[0141] the composition having after compounding a viscosity in the molten state of from 10,000 to 300,000 Pa.s, preferably from 15,000 to 220,000 Pa.s, as measured in plane-plane geometry according to standard ISO 6721-10:2015 at a temperature of 250°C, a frequency of 0.292 rad / s and a deformation of 2%,

[0142] the sum of the constituents a) + b) + c) making 100% by weight.

[0143] In one embodiment, said composition comprises:

[0144] a) from 88 to 99.95% of at least one semi-crystalline aliphatic polyamide having a number of carbons per nitrogen atom greater than or equal to 7, in particular greater than or equal to 8,

[0145] b) from 0.05% to 10% by weight of at least one branching agent chosen from polyepoxy, polyanhydrides and polyisocyanates, in particular maleic polyanhydrides and polyepoxy,

[0146] the composition having after compounding a viscosity in the molten state of from 10,000 to 300,000 Pa.s, preferably from 15,000 to 220,000 Pa.s, as measured in plane-plane geometry according to standard ISO 6721-10:2015 at a temperature of 250°C, a frequency of 0.292 rad / s and a deformation of 2%,

[0147] the sum of the constituents a) + b) making 100% by weight.

[0148] Advantageously in this embodiment, said composition consists of:

[0149] a) from 88 to 99.95% of at least one semi-crystalline aliphatic polyamide having a number of carbons per nitrogen atom greater than or equal to 7, in particular greater than or equal to 8,

[0150] b) from 0.05% to 10% by weight of at least one branching agent chosen from polyepoxy, polyanhydrides and polyisocyanates, in particular maleic polyanhydrides and polyepoxy,

[0151] the composition having after compounding a viscosity in the molten state of from 10,000 to 300,000 Pa.s, preferably from 15,000 to 220,000 Pa.s, as measured in plane-plane geometry according to standard ISO 6721-10:2015 at a temperature of 250°C, a frequency of 0.292.rad / s and a deformation of 2%,

[0152] the sum of the constituents a) + b) making 100% by weight.

[0153] In another embodiment, said composition comprises:

[0154] a) from 88 to 99.85% of at least one semi-crystalline aliphatic polyamide having a number of carbons per nitrogen atom greater than or equal to 7, in particular greater than or equal to 8,

[0155] b) from 0.05% to 10% by weight of at least one branching agent chosen from polyepoxy, polyanhydrides, and polyisocyanates, in particular polyan- maleic hydrides and polyepoxies

[0156] c) from 0.1 to 2% of at least one additive,

[0157] the composition having after compounding a viscosity in the molten state of from 10,000 to 300,000 Pa.s, preferably from 15,000 to 220,000 Pa.s, as measured in plane-plane geometry at a temperature of 250°C, a frequency of 0.292 rad / s and a deformation of 2%,

[0158] the sum of the constituents a) + b) + c) making 100% by weight.

[0159] Advantageously in this embodiment, said composition consists of:

[0160] a) from 88 to 99.85% of at least one semi-crystalline aliphatic polyamide having a number of carbons per nitrogen atom greater than or equal to 7, in particular greater than or equal to 8,

[0161] b) from 0.05% to 10% by weight of at least one branching agent chosen from polyepoxy, polyanhydrides and polyisocyanates, in particular maleic polyanhydrides and polyepoxy,

[0162] c) from 0.1 to 2% of at least one additive,

[0163] the composition having after compounding a viscosity in the molten state of from 10,000 to 300,000 Pa.s, preferably from 15,000 to 220,000 Pa.s, as measured in plane-plane geometry according to standard ISO 6721-10:2015 at a temperature of 250°C, a frequency of 0.292 rad / s and a deformation of 2%,

[0164] the sum of the constituents a) + b) + c) making 100% by weight.

[0165] In a first variant, said composition comprises:

[0166] a) from 89 to 99.9% of at least one semi-crystalline aliphatic polyamide having a number of carbons per nitrogen atom greater than or equal to 7, in particular greater than or equal to 8,

[0167] b) from 0.1 to 9%, by weight of at least one branching agent chosen from polyepoxy, polyanhydrides and polyisocyanates, in particular maleic polyanhydrides and polyepoxy,

[0168] c) from 0 to 2% of at least one additive, in particular from 0.1 to 2%,

[0169] the composition having after compounding a viscosity in the molten state of from 10,000 to 300,000 Pa.s, preferably from 15,000 to 220,000 Pa.s, as measured in plane-plane geometry according to standard ISO 6721-10:2015 at a temperature of 250°C, a frequency of 0.292 rad / s and a deformation of 2%,

[0170] the sum of the constituents a) + b) + c) making 100% by weight.

[0171] In one embodiment of this first variant, said composition comprises:

[0172] a) from 89 to 99.9% of at least one semi-crystalline aliphatic polyamide having a number of carbons per nitrogen atom greater than or equal to 7, in particular greater than or equal to 8,

[0173] b) from 0.1 to 9%, by weight of at least one branching agent chosen from polyepoxy, polyanhydrides and polyisocyanates, in particular maleic polyanhydrides and polyepoxy,

[0174] the composition having after compounding a viscosity in the molten state of from 10,000 to 300,000 Pa.s, preferably from 15,000 to 220,000 Pa.s, as measured in plane-plane geometry according to standard ISO 6721-10:2015 at a temperature of 250°C, a frequency of 0.292 rad / s and a deformation of 2%,

[0175] the sum of the constituents a) + b) making 100% by weight.

[0176] Advantageously in this embodiment of this first variant, the composition consists of:

[0177] a) from 89 to 99.9% of at least one semi-crystalline aliphatic polyamide having a number of carbons per nitrogen atom greater than or equal to 7, in particular greater than or equal to 8,

[0178] b) from 0.1 to 9%, by weight of at least one branching agent chosen from polyepoxy, polyanhydrides and polyisocyanates, in particular maleic polyanhydrides and polyepoxy,

[0179] the composition having after compounding a viscosity in the molten state of from 10,000 to 300,000 Pa.s, preferably from 15,000 to 220,000 Pa.s, as measured in plane-plane geometry according to standard ISO 6721-10:2015 at a temperature of 250°C, a frequency of 0.292 rad / s and a deformation of 2%,

[0180] the sum of the constituents a) + b) making 100% by weight.

[0181] In another embodiment of this first variant, said composition comprises:

[0182] a) from 89 to 99.8% of at least one semi-crystalline aliphatic polyamide having a number of carbons per nitrogen atom greater than or equal to 7, in particular greater than or equal to 8,

[0183] b) from 0.1 to 9%, by weight of at least one branching agent chosen from polyepoxy, polyanhydrides and polyisocyanates, in particular maleic polyanhydrides and polyepoxy,

[0184] c) from 0.1 to 2% of at least one additive,

[0185] the composition having after compounding a viscosity in the molten state of from 10,000 to 300,000 Pa.s, preferably from 15,000 to 220,000 Pa.s, as measured in plane-plane geometry according to standard ISO 6721-10:2015 at a temperature of 250°C, a frequency of 0.292 rad / s and a deformation of 2%,

[0186] the sum of the constituents a) + b) + c) making 100% by weight.

[0187] Advantageously, in this other embodiment of this first variant, the composition consists of:

[0188] a) from 89 to 99.8% of at least one semi-crystalline aliphatic polyamide having a number of carbons per nitrogen atom greater than or equal to 7, in particular greater than or equal to 8,

[0189] b) from 0.1 to 9%, by weight of at least one branching agent chosen from polyepoxy, polyanhydrides and polyisocyanates, in particular maleic polyanhydrides and polyepoxy,

[0190] c) from 0.1 to 2% of at least one additive,

[0191] the composition having after compounding a viscosity in the molten state of from 10,000 to 300,000 Pa.s, preferably from 15,000 to 220,000 Pa.s, as measured in plane-plane geometry according to standard ISO 6721-10:2015 at a temperature of 250°C, a frequency of 0.292 rad / s and a deformation of 2%,

[0192] the sum of the constituents a) + b) + c) making 100% by weight.

[0193] In a second variant, said composition comprises:

[0194] a) from 93 to 99.9% of at least one semi-crystalline aliphatic polyamide having a number of carbons per nitrogen atom greater than or equal to 7, in particular greater than or equal to 8,

[0195] b) from 0.1 to 5% by weight of at least one branching agent chosen from polyepoxy, polyanhydrides and polyisocyanates, in particular maleic polyanhydrides and polyepoxy,

[0196] c) from 0 to 2% of at least one additive, in particular from 0.1 to 2%,

[0197] the composition having after compounding a viscosity in the molten state of from 10,000 to 300,000 Pa.s, preferably from 15,000 to 220,000 Pa.s, as measured in plane-plane geometry according to standard ISO 6721-10:2015 at a temperature of 250°C, a frequency of 0.292 rad / s and a deformation of 2%,

[0198] the sum of the constituents a) + b) + c) making 100% by weight.

[0199] In one embodiment of this second variant, said composition understand :

[0200] a) from 93 to 99.9% of at least one semi-crystalline aliphatic polyamide having a number of carbons per nitrogen atom greater than or equal to 7, in particular greater than or equal to 8,

[0201] b) from 0.1 to 5% by weight of at least one branching agent chosen from polyepoxy, polyanhydrides and polyisocyanates, in particular maleic polyanhydrides and polyepoxy,

[0202] the composition having after compounding a viscosity in the molten state of from 10,000 to 300,000 Pa.s, preferably from 15,000 to 220,000 Pa.s, as measured in plane-plane geometry according to standard ISO 6721-10:2015 at a temperature of 250°C, a frequency of 0.292 rad / s and a deformation of 2%,

[0203] the sum of the constituents a) + b) making 100% by weight.

[0204] Advantageously, in this embodiment of this second variant, said com- position consists of:

[0205] a) from 93 to 99.9% of at least one semi-crystalline aliphatic polyamide having a number of carbons per nitrogen atom greater than or equal to 7, in particular greater than or equal to 8,

[0206] b) from 0.1 to 5% by weight of at least one branching agent chosen from polyepoxy, polyanhydrides and polyisocyanates, in particular maleic polyanhydrides and polyepoxy,

[0207] the composition having after compounding a viscosity in the molten state of from 10,000 to 300,000 Pa.s, preferably from 15,000 to 220,000 Pa.s, as measured in plane geometry according to standard ISO 6721-10:2015 at a temperature of 250°C, a frequency of 0.292 rad / s and a deformation of 2%,

[0208] the sum of the constituents a) + b) making 100% by weight.

[0209] In another embodiment of this second variant, said composition comprises:

[0210] a) from 93 to 99.8% of at least one semi-crystalline aliphatic polyamide having a number of carbons per nitrogen atom greater than or equal to 7, in particular greater than or equal to 8,

[0211] b) from 0.1 to 5% by weight of at least one branching agent chosen from polyepoxy, polyanhydrides and polyisocyanates, in particular maleic polyanhydrides and polyepoxy,

[0212] c) from 0.1 to 2% of at least one additive,

[0213] the composition having after compounding a viscosity in the molten state of from 10,000 to 300,000 Pa.s, preferably from 15,000 to 220,000 Pa.s, as measured in plane-plane geometry according to standard ISO 6721-10:2015 at a temperature of 250°C, a frequency of 0.292 rad / s and a deformation of 2%,

[0214] the sum of the constituents a) + b) + c) making 100% by weight.

[0215] Advantageously, in this other embodiment of this second variant, said composition consists of:

[0216] a) from 93 to 99.8% of at least one semi-crystalline aliphatic polyamide having a number of carbons per nitrogen atom greater than or equal to 7, in particular greater than or equal to 8,

[0217] b) from 0.1 to 5% by weight of at least one branching agent chosen from polyepoxy, polyanhydrides, and polyisocyanates, in particular maleic polyanhydrides and polyepoxy,

[0218] c) from 0.1 to 2% of at least one additive,

[0219] the composition having after compounding a viscosity in the molten state of from 10,000 to 300,000 Pa.s, preferably from 15,000 to 220,000 Pa.s, as measured in plane-plane geometry according to standard ISO 6721-10:2015 at a temperature of 250°C, a frequency of 0.292 rad / s and a deformation of 2%,

[0220] the sum of the constituents a) + b) + c) being 100% by weight.

[0221] In a third variant, said composition comprises:

[0222] a) from 98 to 99.9% of at least one semi-crystalline aliphatic polyamide having a carbon number per nitrogen atom greater than or equal to 7, in particular greater than or equal to 8,

[0223] b) from 0.1 to 2% by weight of at least one branching agent chosen from polyepoxy, polyanhydrides and polyisocyanates, in particular maleic polyanhydrides and polyepoxy,

[0224] c) from 0 to 2% of at least one additive, in particular from 0.1 to 2%,

[0225] the composition having, after compounding, a viscosity in the molten state of from 10,000 to 300,000 Pa.s, preferably from 15,000 to 220,000 Pa.s, as measured in plane-plane geometry according to the ISO standard 6721-10:2015 at a temperature of 250°C, a frequency of 0.292 rad / s and a deformation of 2%,

[0226] the sum of the constituents a) + b) + c) being 100% by weight.

[0227] In one embodiment of this third variant, said composition comprises:

[0228] a) from 98 to 99.9% of at least one semi-crystalline aliphatic polyamide having a number of carbons per nitrogen atom greater than or equal to 7, in particular greater than or equal to 8,

[0229] b) from 0.1 to 2% by weight of at least one branching agent chosen from polyepoxy, polyanhydrides and polyisocyanates, in particular maleic polyanhydrides and polyepoxy,

[0230] the composition having, after compounding, a viscosity in the molten state of from 10,000 to 300,000 Pa.s, preferably from 15,000 to 220,000 Pa.s, as measured in plane-plane geometry according to standard ISO 6721-10:2015 at a temperature of 250°C, a frequency of 0.292 rad / s and a deformation of 2%,

[0231] the sum of constituents a) + b) being 100% by weight.

[0232] Advantageously, in this embodiment of this third variant, said composition consists of:

[0233] a) from 98 to 99.9% of at least one semi-crystalline aliphatic polyamide having a number of carbons per nitrogen atom greater than or equal to 7, in particular greater than or equal to 8,

[0234] b) from 0.1 to 2% by weight of at least one branching agent chosen from polyepoxy, polyanhydrides and polyisocyanates, in particular maleic polyanhydrides and polyepoxy,

[0235] the composition having, after compounding, a viscosity in the molten state of from 10,000 to 300,000 Pa.s, preferably from 15,000 to 220,000 Pa.s, such that measured in plane-plane geometry according to ISO 6721-10:2015 at a temperature of 250°C, a frequency of 0.292 rad / s and a deformation of 2%,

[0236] the sum of the constituents a) + b) making 100% by weight.

[0237] In another embodiment of this third variant, said composition comprises:

[0238] a) from 96 to 99.8% of at least one semi-crystalline aliphatic polyamide having a number of carbons per nitrogen atom greater than or equal to 7, in particular greater than or equal to 8,

[0239] b) from 0.1 to 2% by weight of at least one branching agent chosen from polyepoxy, polyanhydrides and polyisocyanates, in particular maleic polyanhydrides and polyepoxy,

[0240] c) from 0.1 to 2% of at least one additive,

[0241] the composition having after compounding a viscosity in the molten state of from 10,000 to 300,000 Pa.s, preferably from 15,000 to 220,000 Pa.s, as measured in plane-plane geometry according to standard ISO 6721-10:2015 at a temperature of 250°C, a frequency of 0.292 rad / s and a deformation of 2%,

[0242] the sum of the constituents a) + b) + c) making 100% by weight.

[0243] Advantageously, in this other embodiment of this third variant, said composition consists of:

[0244] a) from 96 to 99.8% of at least one semi-crystalline aliphatic polyamide having a number of carbons per nitrogen atom greater than or equal to 7, in particular greater than or equal to 8,

[0245] b) from 0.1 to 2% by weight of at least one branching agent chosen from polyepoxy, polyanhydrides and polyisocyanates, in particular maleic polyanhydrides and polyepoxy,

[0246] c) from 0.1 to 2% of at least one additive,

[0247] the composition having after compounding a viscosity in the molten state of from 10,000 to 300,000 Pa.s, preferably from 15,000 to 220,000 Pa.s, as measured in plane-plane geometry according to standard ISO 6721-10:2015 at a temperature of 250°C, a frequency of 0.292 rad / s and a deformation of 2%,

[0248] the sum of the constituents a) + b) + c) making 100% by weight.

[0249] In all variants and embodiments of the compositions described above:

[0250] the MVR (volume flow index) as determined according to ISO 1133:2011 with a weight of 21.6 kg and at a temperature of 275°C is between 2 and 25 cmVIO min, advantageously between 5 and 20 cm3 / 10 min, very advantageously between 6 and 18 cm3 / 10 min.

[0251] The branching agent and the polyamide are linked by a covalent bond, advantageously Typically the branching agent and the polyamide are linked by an amide, ester or urea function.

[0252] Advantageously at least 5% by weight, very advantageously at least 15% by weight of the polyamide is covalently bonded to the branching agent,

[0253] the ratio of the melt viscosities as measured in plane-plane geometry at 0.292 rad.s 7292 rad.s 1 of said compositions is from 10 to 200, advantageously from 25 to 150. This ratio makes it possible to determine the branching rate of the polyamide of said composition. The higher the ratio, the more the polyamide is branched in the composition. Consequently, the polyamide must be fluid at 292 rad.s 1 and viscous at 0.292 rad.s 1 ;

[0254] the viscosity at 292 rad.s-1 is between 400 and 2000 and preferably between 600 and 1550;

[0255] The rheotensile strength at 250°C of the composition after compounding is from 22 mN to 200 mN, in particular from 25 mN to 150 mN; this strength determines the melt strength of the polyamide, the greater the strength, the less the polyamide is fine;

[0256] The Rheotens force can for example be determined using a Rheotens 71.97 device from Gottfert. A Rheotens device is a device equipped with toothed wheels capable of pulling on a rod at the outlet of a Rheotester 2000 capillary rheometer from Gottfert: shear at the capillary 100s-1 die of L / D=30 and D=1mm temperature 250°C, distance between rod outlet and axis of the toothed wheels 105mm, acceleration of the wheels 2.4mm / s 2

[0257] the swelling rate at the extruder outlet of the composition after compounding is greater than 1.15, preferably greater than 1.2. The swelling rate is achieved according to the operating method:

[0258] A 25 cm tubular parison is extruded using a blow molding line equipped with an accumulator. The expulsion speed is set at 0.lm / s, the temperature of the extrudate is checked manually using a thermal probe. The measurement of the diameter of the parison is carried out 10 cm below the die. 5 measurements are carried out to obtain an average. The temperature is chosen according to the flow characteristics of the polymer to limit the fining of the parison as much as possible.

[0259] The resistance of the parison makes it possible to analyze the capacity of the material to counterbalance the effect of gravity. Under its weight, a parison extruded horizontally or vertically will flow, thus modifying its dimensions. The resistance of the vertical parison of the composition after compounding is between 15 and 50 s, in particular between 20 and 45 s. These measurements were carried out as follows:

[0260] a parison weighing 1.2kg and 190mm long is extruded at a speed expulsion rate set at 0.lm / s. The time required for the parison length to increase by 40% by fining is measured. A long time will be representative of a viscous material. The temperature is chosen according to the flow characteristics of the polymer to limit the fining of the parison as much as possible.

[0261] Decompression tests under Hydrogen have shown that a quantity of shock modifier in the composition of the material less than or equal to 10% by mass makes it possible to avoid and limit cavitation mechanisms (blistering). The sample undergoes a pressure increase from 1 to 40 MPa with a speed of IMPa.min-1, the latter is maintained at 40 MPa for 7 days so that it reaches a saturated state. The decompression phase is carried out with a speed of 5 MPa.min-1. The samples are observed under a scanning electron microscope in order to observe any cavitations.

[0262] The compositions according to the invention resist decompression tests under hydrogen.

[0263] According to a second aspect, the present invention relates to a single-layer or multi-layer tubular structure intended for the transport, distribution or storage of hydrogen, comprising at least one sealing layer (1) comprising a composition as defined above.

[0264] In an embodiment of this second aspect, said structure is intended for the transport of hydrogen, said sealing layer having a total proportion of contaminants present in the hydrogen and extracted from said sealing layer after contact of the hydrogen therewith, less than or equal to 3% by weight, in particular less than 2% by weight of the sum of the constituents of the composition of said sealing layer, the total proportion of contaminants being determined according to a contaminant test as defined in the CSA / ANSI CHMC 2:19 standard.

[0265] Said sealing layer is therefore in contact with hydrogen.

[0266] In another embodiment of this second aspect, said structure further comprises at least one composite reinforcing layer (2), said innermost composite reinforcing layer being welded or not, to said outermost adjacent sealing layer.

[0267] Said composite reinforcement layer is therefore above said sealing layer which is in contact with the hydrogen.

[0268] The number of composite reinforcement layers is from 1 to m.

[0269] The composite reinforcing layer may consist of a fibrous material in the form of continuous fibers impregnated with a composition comprising predominantly at least one polymer P2j, j=1 to m, m being the number of reinforcing layers, in particular an epoxy or epoxy-based resin or a resin based on polyisocyanates, in particular polyisocyanurates,

[0270] Polymer P2j:

[0271] The polymer P2j can be thermoplastic or thermosetting.

[0272] Thermoplastic polymer P2j:

[0273] Thermoplastic, or thermoplastic polymer, is understood to mean a material that is generally solid at room temperature, which may be semi-crystalline or amorphous, in particular semi-crystalline, and which softens upon an increase in temperature, in particular after passing its glass transition temperature (Tg) and flows at a higher temperature when it is amorphous, or which may exhibit a frank melting upon passing its so-called melting temperature (Tf) when it is semi-crystalline, and which becomes solid again upon a decrease in temperature below its crystallization temperature, Te, (for a semi-crystalline) and below its glass transition temperature (for an amorphous).

[0274] Tg, Te and Tf are determined by differential scanning calorimetry (DSC) according to standard 11357-2:2013 and 11357-3:2013 respectively.

[0275] The number-average molecular mass Mn of said thermoplastic polymer is preferably in a range from 10000 to 40000, preferably from 10000 to 30000. These Mn values ​​may correspond to inherent viscosities greater than or equal to 0.8 as determined in m-cresol according to ISO 307:2007 but by changing the solvent (use of m-cresol instead of sulfuric acid and the temperature being 20°C).

[0276] Examples of suitable semi-crystalline thermoplastic polymers in the present invention include:

[0277] polyamides, in particular comprising an aromatic and / or cycloaliphatic structure, including copolymers, for example polyamide-polyether copolymers, polyesters,

[0278] polyaryletherketones (PAEK),

[0279] polyetherether ketones (PEEK),

[0280] polyetherketone ketones (PEKK),

[0281] polyetherketoneetherketone ketones (PEKEKK),

[0282] polyimides, in particular polyetherimides (PEI) or polyamide-imides,

[0283] polysulfones (PSU), in particular polyarylsulfones such as polyphenyl sulfones (PPSU),

[0284] polyethersulfones (PES).

[0285] Semi-crystalline polymers are more particularly preferred, and in particular polyamides and their semi-crystalline copolymers.

[0286] The nomenclature used to define polyamides is described in the ISO 1874-1:2011 standard "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 the person skilled in the art.

[0287] The polyamide may be a homopolyamide or a copolyamide or a mixture thereof.

[0288] Advantageously, the semi-crystalline polyamides are semi-aromatic polyamides, in particular a semi-aromatic polyamide of formula X / YAr, as described in EPI505099, 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 from 4 to 36, advantageously from 9 to 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 aliphatic diacids, linear or branched, cycloaliphatic diacids and aromatic diacids;

[0289] XT denotes a unit obtained from the polycondensation of a Cx diamine and terephthalic acid, with x representing the number of carbon atoms of the Cx diamine, x being from 5 to 36, advantageously from 9 to 18, in particular a polyamide of formula A / 5T, A / 6T, A / 9T, A / 10T or A / 1 1T, A being as defined above, in particular a polyamide chosen from a PA MPMDT / 6T, a PA11 / 10T, a PA 5T / 10T, a PA 11 / BACT, a PA 11 / 6T / 10T, a PA MXDT / 10T, a PA MPMDT / 10T, a PA BACT / 10T, a PA BACT / 6T, PA BACT / 10T / 6T, a PA 11 / BACT / 6T, PA 11 / MPMDT / 6T, PA 11 / MPMDT / 10T, PA 11 / BACT / 10T, one PA 11 / MXDT / 10T, one 11 / 5T / 10T.

[0290] T corresponds to terephthalic acid, MXD corresponds to m-xylylenediamine, MPMD corresponds to methylpentamethylenediamine and BAC corresponds to bis(aminomethyl)cyclohexane. Said semi-aromatic polyamides defined above have in particular a Tg greater than or equal to 80°C.

[0291] Thermosetting polymer P2j:

[0292] The thermosetting polymers are chosen from epoxy or epoxy-based resins, polyesters, vinylesters, polyisocyanate-based resins, in particular polyisocyanurates, and polyurethanes, or a mixture thereof, in particular epoxy or epoxy-based resins or a polyisocyanate-based resin, in particular polyisocyanurates.

[0293] Advantageously, each composite reinforcement layer consists of a composition comprising the same type of polymer, in particular an epoxy or epoxy-based resin or a resin based on polyisocyanates, in particular polyisocyanurates.

[0294] Said composition comprising said polymer P2j may be transparent to radiation suitable for welding.

[0295] Concerning the fibers constituting said fibrous material, these are in particular fibers of mineral, organic or vegetable origin.

[0296] Advantageously, said fibrous material may be sized or not sized.

[0297] Said fibrous material can therefore comprise up to 3.5% by weight of a material of an organic nature (thermosetting or thermoplastic resin type) called sizing.

[0298] 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, polyester 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 thermoplastic polymer or polymer mixture constituting the pre-impregnation matrix when the latter is amorphous, or greater than the Tf of the thermoplastic polymer or polymer mixture constituting the pre-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 pre-impregnation matrix when the latter is amorphous, or higher than the Tf of the polymer or mixture of thermoplastic polymers constituting the pre-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, particularly spider silk, sisal, and other cellulosic fibers, particularly viscose.These plant-based fibers can be used pure, treated or coated with a coating layer, in order to facilitate adhesion and impregnation of the thermoplastic polymer matrix.

[0299] The fibrous material may also be a fabric, braided or woven with fibers.

[0300] It may also correspond to fibers with holding threads.

[0301] These constituent 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.

[0302] Organic fiber wicks can have several weights. They can furthermore present several geometries. The fibers constituting the fibrous material can also be in the form of a mixture of these reinforcing fibers of different geometries. The fibers are continuous fibers.

[0303] Preferably the fibrous material is chosen from glass fibers, carbon fibers, basalt or basalt-based fibers, or a mixture thereof, in particular carbon fibers.

[0304] It is used in the form of one wick or several wicks.

[0305] According to a third aspect, the present invention relates to the use of 0.05% to 10%, in particular 0.1 to 9% by weight of at least one branching agent chosen from polyepoxy, polyanhydrides and polyisocyanates, in particular maleic polyanhydrides and polyepoxy, with 88 to 99.95%, in particular 89 to 99.9% of at least one semi-crystalline aliphatic polyamide having a carbon number per nitrogen atom greater than or equal to 7, in particular greater than or equal to 8, and optionally an additive for the constitution of a blow-molding or extrusion composition, in particular blow-molding, as defined above, the viscosity of which in the molten state after compounding is between 10,000 and 300,000 Pa.s, preferably between 15,000 and 20,000 Pa.s. at 220,000 Pa.s, as measured in plane-plane geometry according to ISO 6721-10:2015 at a temperature of 250°C, a frequency of 0.292 rad / s and a strain of 2%.

[0306] By "single or multi-layer tubular structure" is meant a tank comprising or consisting of one or more layers, namely a sealing layer and optionally one or more reinforcing layers, or several sealing layers and optionally several reinforcing layers, or several sealing layers and a reinforcing layer or even a sealing layer and a reinforcing layer.

[0307] The single-layer or multi-layer tubular structure in the present invention also designates a pipe or tube intended for the transport of hydrogen from the tank to the fuel cell and which comprises or is made up of one or more layers, as defined above.

[0308] All the characteristics defined above for the first aspect concerning the composition are valid for this third aspect.

[0309] According to a fourth aspect, the present invention relates to a process for preparing a blow-molding or extrusion composition, in particular blow-molding, as defined above, characterized in that it comprises a step of compounding said composition.

[0310] All the characteristics defined above for the first aspect concerning the composition are valid for this fourth aspect.

[0311] The compounding step is carried out in a particular way so that the alloys have melt viscosities ranging from 10,000 to 300,000 Pa.s, preferably from 15,000 to 220,000 Pa.s, as measured in plane geometry according to ISO 6721-10:2015 at a temperature of 250°C, a frequency of 0.292 rad / s and a deformation of 2%.

[0312] These viscosities can for example be obtained by compounding at a temperature of the molten polymer above 280°C, preferably above 300°C by increasing the residence time in the compounder. This branching reaction is advantageously catalyzed with for example phosphonium salts or hindered amines. The average residence time is advantageously from 20 seconds to 10 minutes, more advantageously from 45 seconds to 6 minutes.

[0313] According to a fifth aspect, the present invention relates to a process for preparing a single-layer or multi-layer tubular structure as defined above, characterized in that it comprises a step of blow-molding or extrusion, in particular blow-molding, of a composition as defined above.

[0314] In one embodiment of this fifth aspect, the method comprises a prior step of compodding a composition as defined above.

[0315] The preliminary compounding step is notably carried out as defined above.

[0316] All the characteristics defined above for the first aspect concerning the composition are valid for this fifth aspect.

[0317] EXAMPLES

[0318] The comparative compositions (CEI to CE4) and of the invention (Cil to CI6) of Table 2 below were prepared by compouding under the following conditions:

[0319] The alloys were manufactured using a ZSK 40 mm twin-screw extruder (Coperion). The barrel temperature was set at 280 °C and the screw speed was 300 rpm with a flow rate of 60 kg / h.

[0320] The PA6 used is a polyamide 6 having an acid chain end concentration of 25 peq / g and an amine chain end concentration of 22 peq / g.

[0321] The PA610 used is a polyamide 610 having an acid chain end concentration of 27 peq / g and an amine chain end concentration of 19 peq / g.

[0322] The PA612 used is a polyamide 612 having an acid chain end concentration of 22 peq / g and an amine chain end concentration of 20 peq / g.

[0323] The PA11 used is a polyamide 11 catalyzed with phosphoric acid having an acid chain end concentration of 30 peq / g and an amine chain end concentration of 33 peq / g.

[0324] Joncryl ADR 4400 is from BASF.

[0325] The Xibond 125 is from Polyscope.

[0326] Lotader 3410 is SK functional polymer.

[0327] The stabilizer Anox NBD TL 89 is from SI group.

[0328] Melt viscosity was measured using an Ares G2 Rotational Rheometer equipped with a 25mm plane-plane geometry at a temperature of 250°C, at 292 rad / s and at 0.292 rad / s (dwell time before launch 5 min under nitrogen, deformation of 1 to 10%, scanning from 628rad / s to 0.062rad / s and 3 points per decade, taking one point over 3 cycles, gap of 1.5mm)

[0329] The Rheotens force is determined using a Rheotens 71.97 device from Gottfert. A Rheotens device is a device equipped with toothed wheels capable of pulling on a rod at the outlet of a Gottfert Rheotester 2000 capillary rheometer shear at the capillary 100s-1 die of L / D=30 and D=1mm temperature 250°C, distance between rod outlet and axis of the toothed wheels 105mm, wheel acceleration 2.4mm / s2 The water uptake is determined either in an oven under a controlled atmosphere at 100% Rh or in water, in all cases after saturation at 70°C and the measurement of this water uptake is made by weighing the sample at 23°C, for regular sampling times, spaced several days apart, until a state of equilibrium is observed, which is reached when the mass of the sample becomes constant (to the uncertainty of the measurement) for three consecutive sampling times.In the case of conditioning in water, the equilibrium reached corresponds to the water saturation of the polymer, at a temperature of 70°C.

[0330] Liners with a thickness of 2 mm according to the compositions of the invention were prepared by blow molding and the hydrogen permeability at 15°C was tested.

[0331] This consists of sweeping the upper face of the film with the test gas (Hydrogen) and measuring by gas chromatography the flux which diffuses through the film in the lower part, swept by the carrier gas: Nitrogen.

[0332] The experimental conditions are presented in Table 1:

[0333] [Tables 1] Device Coupling LYSSY GPM500 / GC Chromatographic detection (TCD) Column Poraplot Q (L=27.5m, Dint=0.530mm, Ep.film=20p) Carrier gas NITROGEN Diffusing gas HYDROGEN U (H2) Test surface 50cm2 Calibration Absolute by direct injection through a septum Pressure at the column head 18psi Temperature Oven Isotherm 30°C Detector temperature 200°C detector: TCD [-] Injector temperature Temperature of the lyssy injection loop Temperature / Relative humidity 23°C / 0%RH

[0334] The results obtained are then compared to the requirements of the CSA / ANSI standard CHMC 2.19 described in Table 2 “material compatibility qualification rating”:

[0335] [Tables2] Material compatibility qualification score Evaluation test reference clause Unit Material compatibility score 10 8 6 4 2 0 Permeation flux 5.2 NcmVh <0.8 >0.8- 1.5 > 1.5 - 3 >3 - 6 >6- 16 >16

[0336] The compositions of the invention and the comparative compositions were tested on several parameters. The results are detailed in Table 3.

[0337] [Tables3] CE 1 CE 2 CE 3 CE 4 CI 1 CI 2 CI 3 CI 4 CI 5 CI 6 PA 6 76 PA 612 91 PA 610 91 PA 11 99 84 84 98 98.5 94 91 JONCRYL ADR 4400 0.5 Xibond 125 15 1 Lotader 3410 23 15 4 8 8 8 anox TL 89 stab 1 1 1 1 1 1 1 1 1 1 total 100 100 100 100 100 100 100 100 100 100 viscosity at 0.292 rad / s 9840 5819 7127 8730 2 191179 14302 6 2364 5 3104 7 30 267 2894 0 rheotens force (mN) 20 13 15 28 60 45 22 23 23 23 Water uptake (% H2O) Conditions 100% RH at 23°C 7.3 1 1 1 1 1 1 1 2 2.3 H2 permeability (Material compatibility rating from Table 2) 10 8 8 6 8 8 8 8 10 10

[0338] The results show that the use of a branching agent in a particular range and of a polyamide with an average number of carbon atoms per nitrogen atom greater than or equal to 7 makes it possible to obtain compositions having the best compromise on the different characteristics such as rheotensile strength, water uptake, viscosity at 0.292 rad / s and hydrogen permeability.

Claims

Claims

1. Blow-molding or extrusion composition, in particular blow-molding, comprising by weight: a) from 93 to 99.9% of at least one semi-crystalline aliphatic polyamide having a carbon number per nitrogen atom greater than or equal to 7, in particular greater than or equal to 8, b) from 0.1 to 5% by weight of at least one branching agent chosen from polyepoxy, polyanhydrides, and polyisocyanates, in particular maleic polyanhydrides and polyepoxy, c) from 0 to 2% of at least one additive, in particular from 0.1 to 2%, the composition having, after compounding, a viscosity in the molten state of from 10,000 to 300,000 Pa.s, preferably from 15,000 to 220,000 Pa.s, as measured in plane-plane geometry according to the ISO standard 6721-10:2015 at a temperature of 250°C, a frequency of 0.292 rad / s and a deformation of 2%, the sum of the components a) + b) + c) being 100% by weight.

2. Blow-molding or extrusion composition, in particular blow-molding, according to claim 1, characterized in that said branching agent has an average functionality in epoxy, anhydride or isocyanate functions of from 1.8 to 200, preferably from 2.1 to 150.

3. Blow-molding or extrusion composition, in particular blow-molding, according to claim 2, characterized in that said branching agent has an average equivalent weight in epoxy, anhydride or isocyanate functions of from 100 to 10,000 g / mol, preferably from 120 to 6000 g / mol, in particular from 140 to 3300 g / mol.

4. Blow-molding or extrusion composition, in particular blow-molding, according to one of claims 1 to 3, characterized in that the rheotensile force of the composition after compounding is from 22 mN to 200 mN, in particular from 25 mN to 150 mN.

5. Blow-molding or extrusion composition, in particular blow-molding, according to one of claims 1 to 4, characterized in that said semi-crystalline aliphatic polyamide is chosen from PA610, PA612, PA 614, PA 10, PAU and PA12, in particular PA610, PA612 and PAU.

6. Single-layer or multi-layer tubular structure intended for transport, the distribution or storage of hydrogen, in particular hydrogen, comprising at least one sealing layer (1) comprising a composition as defined in one of claims 1 to 5.

7. Single-layer or multi-layer tubular structure according to claim 6, characterized in that said sealing layer has a total proportion of contaminants present in the hydrogen and extracted from said sealing layer after contact of the hydrogen therewith, less than or equal to 3% by weight, in particular less than 2% by weight of the sum of the constituents of the composition of said sealing layer, the total proportion of contaminants being determined according to a contaminant test as defined in the CSA / ANSI CHMC 2:19 standard.

8. Single-layer or multi-layer tubular structure according to claim 6 or 7, characterized in that it further comprises at least one composite reinforcing layer (2), said innermost composite reinforcing layer being welded or not, to said outermost adjacent sealing layer.

9. Use of 0.1 to 5% by weight of at least one branching agent chosen from polyepoxy, polyanhydrides and polyisocyanates, in particular maleic polyanhydrides and polyepoxy, with 93 to 99.9% of at least one semi-crystalline aliphatic polyamide having a carbon number per nitrogen atom greater than or equal to 7, in particular greater than or equal to 8, and optionally an additive for the constitution of a blow-molding or extrusion composition, in particular blow-molding, as defined in one of claims 1 to 7, the viscosity of which in the molten state after compounding is between 10,000 and 300,000 Pa.s, preferably between 15,000 and 220,000 Pa.s, as measured in plane-plane geometry according to the ISO standard 6721-10:2015 at a temperature of 250°C, a frequency of 0.292 rad / s and a deformation of 2%.

10. Process for preparing a blow-molding or extrusion composition, in particular blow-molding, as defined in one of claims 1 to 5, characterized in that it comprises a step of compounding said composition.

11. Process for preparing a single-layer or multi-layer tubular structure as defined in claim 6, characterized in that it comprises a step of blow-molding or extrusion, in particular blow-molding, of a composition as defined in one of of claims 1 to 5.

12. Process for preparing a single-layer or multi-layer tubular structure according to claim 11, characterized in that it comprises a prior step of compounding a composition as defined in one of claims 1 to 5.