Multi-layered tubular structure with low extractables content for transporting hydrogen - Patents.com

Abstract

The present invention relates to a multi-layer tubular structure (MLT) intended for transporting hydrogen, comprising, from the outside to the inside, at least one barrier layer (1) and at least one inner layer (2) located underneath said barrier layer, The inner layer (2), or the combination of layer (2) and other optional layers located below the barrier layer, comprises, on average, 0% to 1.5% by weight of a plasticizer, based on the total weight of the composition of layer (2), or based on the total weight of the composition of layer (2) and other optional layers located below the barrier layer, The inner layer (2) exhibits an extractables content of not more than 3% by weight, in particular less than 2% by weight, of the sum of the components of the composition, the inner layer (2) mainly comprises at least one polyamide of aliphatic type or consists of more than 75% aliphatic units, the aliphatic polyamide being - a polyamide represented by A, A having an average number of carbon atoms per nitrogen atom of the formula: - a polyamide of the formula B, B having an average number of carbon atoms per nitrogen atom of the formula: - a polyamide represented by the formula C C having an average number of carbon atoms per nitrogen atom of 9 to 18, preferably 10 to 18; provided that, when the inner layer (2) comprises at least three polyamides, at least one of the polyamides A, B, and C is excluded.

Description

[Technical field]

[0001] The present invention relates to a multi-layered tubular structure exhibiting low extractable content and its use for transporting hydrogen.

[0002] The invention relates more particularly to tubes present in motor vehicles, which may be intended for example for the transport of hydrogen to supply fuel cells. [Background technology]

[0003] Hydrogen is currently a subject of great interest to many manufacturers, especially in the automotive field. One of the aims pursued is to provide vehicles that are less and less polluting. Electric or hybrid vehicles equipped with batteries are therefore intended to gradually replace thermal vehicles such as gasoline or diesel vehicles. In fact, the battery proves to be 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 from the external environment, which may be extreme temperatures and fluctuating humidity. Fire risks must also be avoided.

[0004] Moreover, to avoid damaging the battery cells and to preserve their service life, it is important that the operating temperature does not exceed 55°C. Conversely, in winter, for example, it may be necessary to increase the battery temperature to optimize its operation.

[0005] Furthermore, electric vehicles still suffer from several problems today, including battery range, the use of rare earth metals in the batteries, which are not inexhaustible, recharging times that are much longer than the time it takes to fill the tank, and issues with generating electricity in various countries to be able to charge the batteries.

[0006] Hydrogen can therefore be converted into electricity by fuel cells to power electric vehicles, making it an alternative to batteries.

[0007] Supplying hydrogen to a fuel cell therefore requires both a hydrogen storage tank on the vehicle and a pipe to transport the hydrogen from the tank to the fuel cell.

[0008] Hydrogen tanks or pipes for transporting hydrogen generally consist of a metal or thermoplastic liner (or gas-tight layer) that must prevent hydrogen permeation.

[0009] The basic principle is to separate two important functions, gas tightness and mechanical strength, to manage them independently of each other. In this type of tank, a liner (or gas tight sheath) made of thermoplastic resin is combined with a reinforcing structure made of fibers (glass, aramid, carbon), also called reinforcing sheath or layer, which allows operation at much higher pressures while reducing the weight and avoiding the risk of explosive rupture in the event of a violent external attack.

[0010] Hydrogen transport pipes must limit hydrogen permeation as much as possible.

[0011] They should exhibit low hydrogen permeability, since pipe permeability is a key factor in limiting hydrogen loss in the pipe; Good mechanical (fatigue) properties at low temperatures (-40 to -60°C); Heat resistant at 85℃.

[0012] Nevertheless, fuel cells are highly sensitive to a variety of contaminants that degrade their performance quality and durability.

[0013] These contaminants come from several sources: The hydrogen itself resulting from the production process, The manufacture of tanks and / or pipes for the transportation of hydrogen, in which various natural constituents, such as volatile organic compounds or water, are trapped in particular in the thermoplastic polymer of the gas-tight layer and are subsequently extracted by hydrogen coming into contact with said gas-tight layer, The presence of components in the thermoplastic polymer that can be extracted by hydrogen that subsequently comes into contact with the gas-tight layer. It is possible that this is due to

[0014] According to Chen et al. (A Review of PEM Hydrogen Fuel Cell Contamination: Impact, Mechanisms and Mitigation, Journal of Power Sources, 165 (2007), 739-756), hydrogen used as fuel for fuel cells in research, development and demonstration is mainly obtained from commercially available sources. Hydrogen production processes are mainly carried out by reforming starting from hydrocarbons or oxygenated hydrocarbons, including methane from natural gas and methanol from biomass, but also by electrolysis, partial oxidation of small organic molecules, and hydrolysis of sodium borohydride.

[0015] Therefore, hydrogen transport pipes for use with fuel cells must not only exhibit the basic properties listed above, but the hydrogen must also contain minimal contaminants that are extracted from the gas-tight layers of the tanks and / or pipes after coming into contact with the gas-tight layers. Summary of the Invention

[0016] This dual problem is solved by providing a multi-layer structure of the present invention for the transport of hydrogen.

[0017] The present invention relates to a multi-layer tubular structure (MLT) intended for transporting hydrogen, comprising, from the outside to the inside, at least one barrier layer (1) and at least one inner layer (2) located below said barrier layer, The inner layer (2), or the combination of layer (2) and other optional layers located below the barrier layer, comprises, on average, 0% to 1.5% by weight of a plasticizer, based on the total weight of the composition of layer (2), or based on the total weight of the composition of layer (2) and other optional layers located below the barrier layer, the inner layer (2) exhibits an extractable content of less than or equal to 3% by weight, in particular less than 2% by weight, of the sum of the components of the composition; The inner layer (2) mainly comprises at least one aliphatic type polyamide or consists of more than 75% aliphatic units, the aliphatic polyamide being - a polyamide represented by A, A having an average number of carbon atoms per nitrogen atom of the formula: - a polyamide of the formula B, B having an average number of carbon atoms per nitrogen atom of the formula: - a polyamide represented by the formula C C having an average number of carbon atoms per nitrogen atom of the formula: is selected from However, when the inner layer (2) contains at least three polyamides, at least one of the polyamides A, B, and C is excluded. This concerns multi-layer tubular structures (MLT).

[0018] It would not depart from the scope of the invention if an object intended for the transport of hydrogen was also used for storing hydrogen.

[0019] The phrase "layer (2) in combination with other optional layers underlying the barrier layer" refers to all layers underlying the barrier layer.

[0020] The inventors have therefore found that the absence, or at least a very low presence, of plasticizer in the inner layer(s), i.e. the layer(s) located below the barrier layer, makes it possible to significantly reduce the proportion of contaminants present in hydrogen and extracted from said inner layer (2) after contact of hydrogen with said inner layer (2), so that the sum of the proportions of said contaminants extracted in hydrogen is less than or equal to 3% by weight, in particular less than 2% by weight, of the sum of the components of the composition.

[0021] In one embodiment, the extractables content is determined according to standard CSA / ANSI CHMC 2:19.

[0022] In another embodiment, the extractables content is determined by filling the tubular structure with alcohol-containing gasoline of FAM-B type at 60° C. for 96 hours, then emptying the contents of the tubular structure, filtering the contents into a beaker, evaporating, and then weighing the evaporation residue, which corresponds to the extractables content.

[0023] In yet another embodiment, the extractables content is determined according to standard CSA / ANSI CHMC 2:19 or by filling the tubular structure with alcohol-containing gasoline of FAM-B type at 60° C. for 96 hours, then emptying the contents of the tubular structure, filtering the contents into a beaker, evaporating and then weighing the evaporation residue, which corresponds to the extractables content.

[0024] Thus, the multi-layer structure of the present invention exhibits good permeability to hydrogen and low extractable volatile organic compounds (VOCs).

[0025] The expression "the inner layer (2) satisfies the test for contaminants present in hydrogen and extracted from the inner layer (2) by hydrogen" means that the proportion of contaminants present in hydrogen, whether in a tank or a pipe, and arising from the inner layer (2) after contact with hydrogen, does not exceed limit values ​​that would interfere with the proper functioning of the fuel cell.

[0026] Standard CSA / ANSI CHMC 2:19 details the procedures used to determine the volatile components in the headspace of polymers during use and exposure to hydrogen.

[0027] The expression "after contact of the latter with hydrogen" refers, as above, to exposure to hydrogen during use. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] Device The test equipment must include the following: (a) Cryofocusing for preconcentrating gas samples; (b) a gas chromatograph using a suitable column connected in series with a suitable selective mass detector; (c) headspace vial (40 ml), septum, closure, and vial sealant; (d) an analytical balance capable of weighing up to 60.0001 g; and (e) A convection oven capable of maintaining a temperature of 70 ± 5°C.

[0029] Testing environment Hydrogen gas purity As explained below, the conditioning hydrogen gas must be of known composition and known purity.

[0030] The purity of the hydrogen gas used to fill the test cells must at least comply with parts 1-3 of ISO standard 14687:2019 or SAE J2719(2015). ISO 14687-2 provides the most stringent hydrogen quality specifications among these ISO standards, with the lowest thresholds for each impurity (see Table 1). SAE J2719 also applies to proton exchange membrane (PEM) fuel cell vehicles and is harmonized with ISO 14687-2. TIFF2024536101000001.tif126170

[0031] Measurement and Instrumentation The temperature at which the hydrogen permeability is measured must be controlled to within ±1°C. The test pressure must be kept constant within 1% of the test value.

[0032] Test procedure The test procedure is described in section 5.6 of the ISO standard 14687:2019.

[0033] Contaminants The term "contaminant" is understood in the broad sense of the term, starting from the moment that said contaminant is extracted from the gas-tight layer by hydrogen and is not yet present in the hydrogen introduced into the multilayer structure for operating a vehicle's fuel cell, for example by the process from which hydrogen is obtained.

[0034] For example, the term "contaminants" includes contaminants that may be produced by stabilizers used in polyamides, such as K + , Cu 2+ , Ni 2+ , and Fe 3+ metal cations such as , organic stabilizers or metal stabilizers themselves, plasticizers, oligomers, in particular caprolactam and its cyclic dimer 1,8-diazacyclotetradecane-2,7-dione (DCDD), e.g. NH3, NO x , SOx x , N2, benzoic acid compounds, volatile organic compounds such as O3, water absorbed into the polyamide after production of the airtight layer, and fatty substances such as oils.

[0035] Thus, volatile organic compounds exclude all other substances listed above.

[0036] The sum of the proportions of the extracted contaminants in the hydrogen is not more than 3% by weight, in particular less than 2% by weight, of the sum of the components of the composition, and thus does not take into account the proportion of contaminants originating from the hydrogen production process or any other source.

[0037] Advantageously, the total proportion of said extracted contaminants in the hydrogen is between 0.01% and 3% by weight, in particular between 0.01% and 2% by weight, more particularly between 0.01% and 1% by weight, in particular between 0.01% and 0.5% by weight.

[0038] In a first alternative form, the extracted contaminants are selected from plasticizers, stabilizers, oligomers, water, fatty substances, volatile organic compounds, and mixtures thereof.

[0039] Advantageously, in this first alternative form, the weight percentage of each individual extracted contaminant is less than 1%.

[0040] In one embodiment of this first alternative form, the composition of the extracted contaminants is as follows: Maximum 1% plasticizer, Maximum 0.5% stabilizer, Maximum 1% oligomers, Maximum 0.5% water, Maximum 0.5% fatty substances, and Maximum 0.5% volatile organic compounds, The total amount of extracted contaminants is less than or equal to 3%, in particular less than 2% by weight of the total components of the composition.

[0041] Advantageously, in this embodiment of this first alternative form, the sum of the proportions of said extracted contaminants in the hydrogen is between 0.01% and 3% by weight, in particular between 0.01% and 2% by weight, more particularly between 0.01% and 1% by weight, in particular between 0.01% and 0.5% by weight.

[0042] Even more advantageously, in this embodiment of this first alternative form, the weight percentage of each individual extracted contaminant is less than 1%.

[0043] In a second alternative, the extracted contaminants are selected from stabilizers, water, oil, volatile organic compounds, and mixtures thereof.

[0044] Advantageously, in this second alternative form, the weight percentage of each individual extracted contaminant is less than or equal to 0.5%.

[0045] In one embodiment of this second alternative form, the composition of the extracted contaminants is as follows: Maximum 0.5% stabilizer, Maximum 0.5% water, Maximum 0.5% fatty substances, and Maximum 0.5% volatile organic compounds, The total amount of contaminants is less than or equal to 2% by weight of the total components of said composition.

[0046] Advantageously, in this embodiment of this second alternative form, the sum of the proportions of said extracted contaminants in the hydrogen is between 0.01% and 2% by weight, more particularly between 0.01% and 1% by weight, in particular between 0.01% and 0.5% by weight.

[0047] Even more advantageously, in this embodiment of this second alternative form, the weight percentage of each individual extracted contaminant is less than or equal to 0.5%.

[0048] Barrier layer The expression "barrier layer" means a layer having properties of low permeability and good resistance to hydrogen, i.e., the barrier layer slows down the passage of hydrogen to other layers of the structure or to the outside of the structure.

[0049] A barrier layer is therefore, first and foremost, a layer which makes it possible to prevent the loss of excess hydrogen into the atmosphere by diffusion, thereby avoiding problems of explosion and fire.

[0050] Advantageously, the barrier layer (1) is leak-tight to hydrogen at 23° C., i.e. the permeability to hydrogen at 23° C. is less than 100 cc.mm / m at 23° C. and 0% relative humidity (RH). 2 .24 hours. less than .atm.

[0051] The transmittance is also expressed as (cc.mm / m 2 It can also be expressed in units of 1.24 hours (Pa).

[0052] Next, the transmittance must be multiplied by 101,325.

[0053] These barrier materials can be polyamides with a low carbon content, i.e. polyamides with an average number of carbon atoms (C) to nitrogen atoms (N) less than 9, preferably semi-crystalline and high melting point polyphthalamide (PPA) and / or non-polyamide barrier materials, such as highly crystalline polymers, such as copolymers of ethylene and vinyl alcohol (hereinafter indicated as EVOH), and in fact functionalized fluorinated materials, such as functionalized polyvinylidene fluoride (PVDF), functionalized copolymers of ethylene and tetrafluoroethylene (ETFE), functionalized copolymers of ethylene, tetrafluoroethylene and hexafluoropropylene (EFEP), functionalized polyphenylene sulfide (PPS) or functionalized polybutylene naphthalate (PBN). If these polymers are not functionalized, it is possible to add intermediate tie layers to ensure good adhesion within the MLT structure.

[0054] In one embodiment, said barrier layer (1) is selected from an EVOH layer, a fluoropolymer layer, in particular a PVDF layer, and a PPA layer.

[0055] Among these barrier materials, EVOH, especially those EVOH most rich in vinyl alcohol comonomer, and impact modified EVOH, are particularly advantageous since they can produce stronger structures.

[0056] In another embodiment, the present invention relates to a multi-layer tubular structure (MLT) as defined above, wherein the barrier layer (1) is an EVOH layer.

[0057] In another embodiment, the present invention relates to a multi-layer tubular structure (MLT) as defined above, wherein the EVOH is an EVOH containing up to 27% ethylene.

[0058] In another embodiment, the present invention relates to a multi-layer tubular structure (MLT) as defined above, wherein the EVOH is an EVOH comprising an impact modifier.

[0059] In another embodiment, the present invention relates to a multi-layer tubular structure (MLT) as defined above, wherein the barrier layer (1) is a polyphthalamide (PPA) layer.

[0060] The term "PPA" refers to compositions based on polyamides containing a majority of units containing at least one aromatic monomer, in particular polyphthalamides of the copolyamide 6.T / x type (where x represents one or more comonomers), such as Zytel HTN products from DuPont, Grivory HT products from EMS, Amodel products from Solvay, Genestar products from Kuraray, such as PPA compositions based on coPA6T / 6I, coPA6T / 66, coPA6T / 6, coPA6T / 6I / 66, PPA9T, coPPA9T / x, PPA10T, coPPA10T / x.

[0061] About Polyamide According to the present patent application, the term "polyamide", also called "PA", covers: - homopolymer, - copolymers or copolyamides based on different amide units, for example copolyamide 6 / 12, which has amide units derived from lactam-6 and lactam-12; - Polyamide alloys, provided that they consist mainly of polyamide.

[0062] There is also a broad category of copolyamides, which are not preferred but are included within the scope of the present invention. They are copolyamides (considered as broad copolyamides because of the predominance of amide units) that contain not only amide units but also units of non-amide nature, such as ether units. The best known examples are PEBA or polyether-block-amides and their copolyamide-ester-ether, copolyamide-ether or copolyamide-ester variants. Among these, mention may be made of PEBA-12, whose polyamide units are the same as those of PA12, and PEBA-6.12, whose polyamide units are the same as those of PA6.12.

[0063] Homopolyamides, copolyamides, and alloys are also differentiated by the number of carbon atoms per nitrogen atom, it being known that there are as many nitrogen atoms as there are amide (-CO-NH-) groups.

[0064] High carbon content polyamides are polyamides with a high content of carbon (C) atoms relative to nitrogen (N) atoms. These polyamides have at least 9 carbon atoms per nitrogen atom, such as polyamide-9, polyamide-12, polyamide-11, polyamide-10.10 (PA10.10), copolyamide 12 / 10.T, copolyamide 11 / 10.T, polyamide-12.T, or polyamide-6.12 (PA6.12), where T stands for terephthalic acid.

[0065] The nomenclature used to define polyamides is described in ISO standard 1874-1:1992, "Plastics - Polyamide (PA) moulding and extrusion materials - Part 1: Designation", in particular page 3 (Tables 1 and 2), and is well known to those skilled in the art.

[0066] Low carbon content polyamides are polyamides that have a low content of carbon (C) atoms relative to nitrogen (N) atoms. These include polyamides having less than about 9 carbon atoms per nitrogen atom, such as polyamide-6, polyamide-6.6, polyamide-4.6, copolyamide-6.T / 6.6, copolyamide 6.I / 6.6, copolyamide 6.T / 6.I / 6.6, or polyamide 9.T, where I represents isophthalic acid.

[0067] In the case of homopolyamides of the PA-XY type (X denotes units derived from diamines and Y denotes units derived from diacids), the number of carbon atoms per nitrogen atom is the average of the number of carbon atoms present in the units resulting from diamine X and diacid Y. Thus, PA6.12 is a PA with 9 carbon atoms per nitrogen atom, in other words, a C9PA. PA6.13 is a C9.5 It is.

[0068] For copolyamides, the number of carbon atoms per nitrogen atom is calculated according to the same principle. The calculation is done on a molar proportion basis from the various amide units. For copolyamides with non-amide type units, the calculation is done only on the part of the amide units. Thus, for example, for PEBA-12, which is a block copolymer of amide-12 and ether units, the average number of carbon atoms per nitrogen atom will be 12 for PA12; for PEBA-6.12, it will be 9, as for PA6.12.

[0069] Thus, polyamides with a high carbon content, such as polyamide PA12 or 11, have difficulty adhering to EVOH polymers, polyamides with a low carbon content, such as polyamide PA6, or alloys of polyamide PA6 with polyolefins (for example Orgalloy® sold by Arkema).

[0070] Layer (2) If only one layer (2) is present, it is in contact with hydrogen.

[0071] If several layers (2) are present, one of the inner layers may exhibit a proportion of plasticizer exceeding 1.5% by weight, but in this case this proportion is compensated for by a very thin layer thickness, so that the average value of the plasticizer present in the combined inner layers does not exceed 1.5%. The proportion of plasticizer in this layer may be up to 15%, but its thickness does not exceed 10% of the total thickness of the tube; preferably, the thickness does not exceed 100 μm.

[0072] This very thin layer can be in direct contact with the barrier layer or can be the innermost layer in contact with hydrogen.

[0073] The expression "the inner layer (2) mainly comprises at least one aliphatic type polyamide" means that the aliphatic type polyamide is present in the layer (2) in a proportion of more than 50% by weight. The aliphatic type polyamide is linear and is not of cycloaliphatic type.

[0074] Advantageously, said predominantly aliphatic type polyamide of layer(s) (2) comprises predominantly aliphatic units, ie more than 50% of aliphatic units.

[0075] Advantageously, said predominantly aliphatic type polyamide of layer(s) (2) consists of more than 75% aliphatic units; preferably, said predominantly aliphatic type polyamide of layer(s) (2) is completely aliphatic.

[0076] In an advantageous embodiment, said inner layer (2), or said layer (2) and each of the other optional layers located below the barrier layer, respectively, comprises from 0% to 1.5% by weight of a plasticizer, relative to the total weight of the composition of layer (2), or relative to the total weight of each of the compositions of layer (2) and the other optional layers located below the barrier layer.

[0077] In an advantageous embodiment, in the multi-layer tubular structure (MLT) defined above, said inner layer (2), or said layer (2) and each of the other optional layers located below the barrier layer, do not contain a plasticizer.

[0078] In this embodiment, all layers underlying the barrier layer are completely free of plasticizer, constituting one of the preferred structures of the present invention.

[0079] In one embodiment, PA12 is excluded from the definition of polyamide C of layer (2) or of any layer (2) present.

[0080] Advantageously, in the multilayer tubular structure (MLT) defined above, the polyamide of the inner layer (2) is a composition based on a polyamide selected from A, B or C defined above, in particular PA6, PA66, PA6 / 66, PA11, PA610, PA612 or PA1012, the corresponding copolyamides and blends of said polyamides or copolyamides, the polyamides obtained from lactam being advantageously washed, and the polyamide of the outer layer (3) is a polyamide selected from B or C defined above, in particular PA11, PA12, PA610, PA612 or PA1012, the corresponding copolyamides and blends of said polyamides or copolyamides, the polyamides obtained from lactam being advantageously washed.

[0081] In another embodiment, the present invention relates to a multi-layer tubular structure (MLT) as defined below, in which the polyamide of at least one of the inner or other layers (2) is a conductive polyamide.

[0082] When the tubular structure of the invention comprises several layers (2), the conductive layer is the innermost layer, ie the layer in contact with hydrogen.

[0083] Advantageously, in the multilayer tubular structure (MLT) defined above, the polyamide of the inner layer (2) is a composition based on a polyamide selected from A, B or C as defined above, in particular PA6, PA66, PA6 / 66, PA11, PA610, PA612 or PA1012, the corresponding copolyamides and blends of said polyamides or copolyamides, the polyamides obtained from lactams being advantageously washed.

[0084] Layer (3) In an advantageous embodiment, the invention relates to a multilayer tubular structure (MLT) as defined above, in which there is at least one further outer layer (3) located on the barrier layer, said outer layer (3) mainly comprising at least one polyamide of aliphatic type or consisting of more than 75% of aliphatic units, in particular said aliphatic polyamide exhibiting an average number of carbon atoms per nitrogen atom between 9.5 and 18, advantageously between 11 and 18.

[0085] The expression "said outer layer (3) mainly comprises at least one aliphatic type polyamide" means that said aliphatic type polyamide is present in a proportion of more than 50% by weight in layer (3). The aliphatic type polyamide is linear and not of cycloaliphatic type.

[0086] Advantageously, said predominantly aliphatic type polyamide of layer(s) (3) comprises predominantly aliphatic units, ie more than 50% of aliphatic units.

[0087] Advantageously, said predominantly aliphatic type polyamide of layer(s) (3) consists of more than 75% aliphatic units; preferably, said predominantly aliphatic type polyamide of layer(s) (3) is completely aliphatic.

[0088] Advantageously, said predominantly aliphatic type polyamide of layer(s) (2) and layer(s) (3) comprises mainly aliphatic units, i.e. more than 50% of aliphatic units.

[0089] Advantageously, said predominantly aliphatic type polyamide of layer(s) (2) and layer(s) (3) consists of more than 75% aliphatic units; preferably, said predominantly aliphatic type polyamide of layer(s) (2) and layer(s) (3) is completely aliphatic.

[0090] Advantageously, the invention relates to a multilayer tubular structure (MLT) as defined above, wherein said outer layer (3) comprises between 0% and 15% of plasticizer relative to the total weight of the composition of layer (3), or the combined outer layers comprise, on average, between 0% and 5% of plasticizer.

[0091] It is possible to include a greater proportion of plasticizer in the outer layer, ie, the layer or layers located above the barrier layer, without significantly increasing the proportion of extractables.

[0092] As already indicated for layer (2), if there are several layers (3), it is also possible for one of the outer layers to exhibit a larger proportion of plasticizer, for example 15% by weight, but in this case the proportion of plasticizer is compensated for by a much thinner layer thickness, so that the average value of plasticizer present in the combined inner layers does not exceed 5%. The proportion of plasticizer in this layer can be up to 15%, but its thickness does not exceed 20% of the total thickness of the tube; preferably, the thickness does not exceed 200 μm.

[0093] Regarding layer (3') Advantageously, the invention relates to a multilayer tubular structure (MLT) comprising a layer (3) as defined above, in which there is at least one second outer layer (3') located on the barrier layer, preferably on layer (3), said layer (3') being plasticized, said plasticizer being present, in particular in a proportion between 1.5% and 15% by weight relative to the total weight of the composition of said layer; preferably, the thickness of said layer (3') represents up to 20% of the total thickness of the tubular structure, in particular up to 200 μm.

[0094] Layer (3'), like layer (3), mainly comprises aliphatic type polyamide, i.e. said aliphatic type polyamide is present in layer (3') in a proportion of more than 50% by weight. The aliphatic type polyamide is linear and not of alicyclic type.

[0095] Advantageously, said predominantly aliphatic type polyamide of layer(s) (3') comprises mainly aliphatic units, ie more than 50% of aliphatic units.

[0096] Advantageously, said predominantly aliphatic type polyamide of layer(s) (3') consists of more than 75% aliphatic units; preferably, said predominantly aliphatic type polyamide of layer(s) (3') is completely aliphatic.

[0097] In another embodiment, the present invention relates to a multi-layer tubular structure (MLT) wherein the layer(s) (3) comprises up to 1.5 wt.-% of a plasticizer, based on the total weight of the composition of said layer or the combined composition of layer (3).

[0098] Advantageously, the multi-layer tubular structure (MLT) comprises only one layer (3) and is free of plasticizers.

[0099] Advantageously, the multi-layer tubular structure (MLT) comprises only one layer (3) and only one layer (2), layers (2) and (3) being free of plasticizers.

[0100] In another embodiment, the present invention relates to a multi-layer tubular structure (MLT) in which the plasticizer content of all layers located above a barrier layer is at most 5 wt.-%, based on the total weight of the composition of all layers located above a barrier layer.

[0101] In another embodiment, the present invention relates to a multi-layer tubular structure (MLT) in which layer (3') is the outermost layer and is the only layer that is plasticized, and layer(s) (3) does not contain a plasticizer.

[0102] The proportion of plasticizer can represent up to 15% by weight of the total weight of the composition of layer (3'). The higher the proportion of plasticizer, the thinner the layer (3'), the thickness of said layer (3') preferably representing up to 20% of the total thickness of the tubular structure, in particular up to 200 μm.

[0103] Advantageously, the multi-layer tubular structure (MLT) consists of four layers, from the outside to the inside: (3') / / (3) / / (1) / / (2), layer (3') being the only layer plasticized in the ratio defined above, layers (3) and (2) being free of plasticizer.

[0104] A multi-layer tubular structure (MLT) consisting of four layers, from outside to inside, (3') / / (3) / / (1) / / (2), shows the advantage of having a breaking elongation at t=0 when the structure is very dry with a very low moisture content of 0%-30% relative humidity, which is very good, especially compared to a structure of layers (3'), (3), and (2) without plasticizer.

[0105] Advantageously, in this latter embodiment, layer (3') is the outermost layer, the latter polyamide being a long-chain polyamide, i.e. having an average number of carbon atoms per nitrogen atom, denoted Cc, between 9.5 and 18, and layer (3) being located between the barrier layer and layer (3'), the polyamide of this layer (3) being a short-chain polyamide, i.e. having an average number of carbon atoms per nitrogen atom, denoted Cc, between 9.5 and 18, A The average number of carbon atoms per nitrogen atom represented by the formula is 4 to 9.

[0106] Advantageously, in this latter embodiment, layer (3') has a thickness comprised between 100 and 200 μm, layer (3) presents a thickness of at least 200 μm and layer (1) presents a thickness comprised between 100 and 200 μm.

[0107] Advantageously, in this latter embodiment, layer (3') is the outermost layer, the latter polyamide is a long-chain polyamide, i.e. the average number of carbon atoms per nitrogen atom, denoted Cc, is between 9.5 and 18, and layer (3) is located between the barrier layer and layer (3'), the polyamide of this layer (3) is a short-chain polyamide, i.e. the average number of carbon atoms per nitrogen atom, denoted CA, is between 4 and 9, layer (3') has a thickness of 100 to 200 μm, layer (3) presents a thickness of at least 200 μm and layer (1) presents a thickness of 100 to 200 μm.

[0108] Advantageously, the multi-layer tubular structure (MLT) consists of five layers, from the outside to the inside: (3') / / (3) / / (1) / / (2) / / (2'), where layer (3') is the only layer plasticized in the ratio defined above, layer (3) and layers (2) and (2') do not contain plasticizer, and layer (2') is a polyamide as defined for layer (2), but different from the polyamide of layer (2). This type of structure allows the elongation at break to be increased under very low humidity conditions without over-hardening the structure.

[0109] Whether the number of layers is three, four, five or more, the preferred tubular structures are those that contain as little plasticizer as possible, with the innermost layer, i.e., the layer closest to the fluid, preferably containing the least amount of plasticizer. These structures can be as follows: - Multi-layer tubular construction (MLT) containing no more than 1.5% plasticizer in the first 50% of the thickness from the inner surface in contact with hydrogen - Multi-layer tubular construction (MLT) containing no more than 1.5% plasticizer in the first 75 percent of the thickness from the inner surface in contact with hydrogen - Multi-layer tubular construction (MLT) containing no more than 1.5% plasticizer in the first 85 percent of the thickness from the inner surface in contact with hydrogen - Multi-Layer Tubular Construction (MLT) with no plasticizers in the first 50% of the thickness from the inner surface in contact with hydrogen - Multi-Layer Tubular Construction (MLT) that is free of plasticizers in the first 75 percent of its thickness from the inner surface in contact with hydrogen - Multi-Layer Tubular Construction (MLT) that is free of plasticizers in the first 85 percent of its thickness from the inner surface in contact with hydrogen

[0110] Layer (4) and Layer (4') In another embodiment, the invention relates to a multilayer tubular structure (MLT) as defined above, in which at least one layer (4) is present, said layer (4) does not comprise more than 15% by weight of plasticizer, preferably not more than 1.5% by weight of plasticizer, relative to the total weight of the constituents of layer (4); advantageously, layer (4) does not comprise a plasticizer, said layer (4) mainly comprising at least one polyamide of aliphatic type or consisting of more than 75% of aliphatic units, wherein said aliphatic polyamide is - polyamides of the type A having an average number of carbon atoms per nitrogen atom of the type CA between 4 and 8.5, advantageously between 4 and 7; - polyamides of the type B, which have an average number of carbon atoms per nitrogen atom of the type CB between 7 and 10, advantageously between 7.5 and 9.5; - polyamides of the formula C, having an average number of carbon atoms per nitrogen atom of the formula CC ranging from 9 to 18, advantageously from 10 to 18; is selected from However, when the layer (4) contains at least three polyamides, at least one of the polyamides A, B, and C is excluded; said layer (4) being located between the barrier layer (1) and the inner layer (2) and / or between the outer layer (3) and the barrier layer (1); or Said layer (4) is a tie layer, the thickness of which represents a maximum of 15% of the (MLT) structure.

[0111] Layer (4), if not a tie layer, is an aliphatic type polyamide as defined for layers (2), (3), and (3').

[0112] Advantageously, the tubular structure of the invention is a four-layer structure consisting of, from the outside to the inside, (3) / / (4) / / (1) / / (2), layer (3) being plasticized by up to 15% as described above, being thin, layer (4), if different from the bonding layer defined above, being free of plasticizer, and layer (2) being free.

[0113] Advantageously, the tubular structure of the invention is a four-layer structure, consisting of the following layers from the outside to the inside: (3) / / (1) / / (4) / / (2), layer (3) being plasticized to a maximum of 15% by weight as defined above and preferably thin, layer (4), if different from the bonding layer defined above, does not contain any plasticizer and layer (2) does not contain any.

[0114] Nevertheless, this layer (3), plasticized by up to 15% by weight, must not be too thin, otherwise there is a risk that the barrier layer will not be centered enough and the MLT structure will not be good enough in terms of impact.On the other hand, if there is an additional thick (non-plasticized) layer between layer (3) and layer (1), the layer can be made very thin, so that layer (1) is not too far off center.

[0115] In these two types of four-layer structures, further layers (2') and / or layers (3') may also be present.

[0116] Said layer (4) may also be a tie layer, as described in particular in EP 1 452 307, EP 1 162 061, EP 1 216 826 and EP 0 428 833.

[0117] It is implied that layers (3) and (1), or (1) and (2), adhere to one another. A tie layer is intended to be interposed between two layers that do not adhere to one another or that are difficult to adhere to one another.

[0118] The bonding layer may be, for example, a composition based on 50% copolyamide 6 / 12 (70 / 30 by weight) with Mn 16,000 and 50% copolyamide 6 / 12 (30 / 70 by weight) with Mn 16,000; a composition based on PP (polypropylene) grafted with maleic anhydride, known under the name Admer QF551A (Mitsui); PA610 (Mn 30,000, as defined elsewhere), 36% PA6 (Mn 28,000) and 1.2% organic stabilizers (0.8% phenol Lowinox 44B25 (Great Lakes), 0.2% phosphorous Irgafos 168 (Ciba) and the UV stabilizer Tinuvin a composition based on PA612 (Mn 29,000, as defined elsewhere), 36% PA6 (Mn 28,000, as defined elsewhere) and 1.2% organic stabilizer (0.8% phenolic Lowinox 44B25 (Great Lakes), 0.2% phosphorous acid Irgafos 168 (Ciba), and 0.2% UV stabilizer Tinuvin 312 (Ciba); a composition based on PA610 (Mn 30,000, as defined elsewhere), 36% PA12 (Mn 35,000, as defined elsewhere) and 1.2% organic stabilizer (0.8% phenolic Lowinox 44B25 (Great Lakes), 0.2% phosphorous acid Irgafos a composition based on PA6 (Mn 28,000, as defined elsewhere), 40% PA12 (Mn 35,000, as defined elsewhere), 20% functionalized EPR Exxelor VA1801 (Exxon), and 1.2% organic stabilizers (phenolic Lowinox 44B25 (Great Lakes), phosphorous acid Irgafos 168 (Ciba), 0.2%, and UV stabilizer Tinuvin 312 (Ciba) 0.2%); 312 (Ciba) 0.2%; or a composition based on PA6.10 (Mn 30,000, as defined elsewhere) 40%, PA6 (Mn 28,000, as defined elsewhere) 40%, and a weight ratio of 68.5 / 30 / 1.The composition may be based on, but is not limited to, 20% of an impact modifier of ethylene / ethyl acrylate / anhydride type 5 (MFI 6 at 190°C, 2.16 kg) and 1.2% of an organic stabilizer consisting of 0.8% phenolic Lowinox 44B25 (Great Lakes), 0.2% phosphorous acid Irgafos 168 (Ciba), and 0.2% UV stabilizer Tinuvin 312 (Ciba).

[0119] In another embodiment, the present invention relates to a multilayer tubular structure (MLT) as defined above, in which a layer (4') is present, said layer (4') mainly comprising at least one polyamide of aliphatic type or consisting of more than 75% of aliphatic units, wherein said aliphatic polyamide is - polyamides of the type A having an average number of carbon atoms per nitrogen atom of the type CA between 4 and 8.5, advantageously between 4 and 7; - polyamides of the type B, which have an average number of carbon atoms per nitrogen atom of the type CB between 7 and 10, advantageously between 7.5 and 9.5; - polyamides of the formula C, having an average number of carbon atoms per nitrogen atom of the formula CC ranging from 9 to 18, advantageously from 10 to 18; is selected from However, when the layer (4') contains at least three polyamides, at least one of the polyamides A, B, and C is excluded, or said layer (4') being a bonding layer, the thickness of which corresponds to a maximum of 15% of the (MLT) structure; The at least one polyamide of the layer (4') can be the same as or different from the polyamide of the layer (4); The layer (4') is located between the outer layer (3) and the barrier layer (1), and the tie layer (4) is located between the barrier layer (1) and the inner layer (2).

[0120] Layer (4') may or may not contain a plasticizer, and is advantageously devoid of plasticizer, as are layers (2) and (4), layer (3) being plasticized as defined above but thin.

[0121] In another embodiment, the present invention relates to a multilayer tubular structure (MLT) as defined above, wherein the polyamide of the inner layer (2) or the polyamide of the outer layer (3) is a fully aliphatic polyamide; preferably, the polyamide of the inner layer (2) and the polyamide of the outer layer (3) are fully aliphatic polyamides.

[0122] Advantageously, in the multilayer tubular structure (MLT) defined above, the polyamide of layers (4) and / or (4') is a blend of polyamides having an average number of carbon atoms per nitrogen atom of 10 or more and polyamides having an average number of carbon atoms per nitrogen atom of 6 or less, such as PA12 and PA6, and anhydride-functionalized (co)polyolefins.

[0123] Advantageously, in the multilayer tubular structure (MLT) defined above, the polyamide of layers (4) and / or (4') is selected from the following binary blends: PA6 and PA12, PA6 and PA612, PA6 and PA610, PA12 and PA612, PA12 and PA610, PA1010 and PA612, PA1010 and PA610, PA1012 and PA612, PA1012 and PA610, and ternary blends: PA6, PA610, and PA12; PA6, PA612, and PA12; PA6, PA614, and PA12.

[0124] About layer (5) In another embodiment, the present invention relates to a multi-layer tubular structure (MLT) as defined above, wherein a second barrier layer (5) is present, said second barrier layer (5) being adjacent or non-adjacent to the first barrier layer (1) and located below said barrier layer (1).

[0125] Particularly in the case of alcohol-containing gasoline, especially methanol-containing gasoline, it may be advantageous to provide a second barrier layer to further limit the diffusion of the gasoline into the atmosphere and / or to reduce the content of extractables.

[0126] This second barrier layer is different from the first barrier layer (1).

[0127] About the second barrier layer In another embodiment, the present invention relates to a multilayer tubular structure (MLT) as defined above, in which the barrier layer (1) is an EVOH layer and the second barrier layer (5) is a PPA layer or a fluoropolymer layer, the fluoropolymer being in particular of the ETFE, EFEP or CPT type.

[0128] Advantageously, the barrier layer (1) is an EVOH layer and the second barrier layer (5) is a PPA layer.

[0129] In another embodiment, the present invention relates to a multi-layer tubular structure (MLT) as defined above, wherein the barrier layer (1) is an EVOH layer and the second barrier layer (5) is a PPA layer.

[0130] In another embodiment, the present invention relates to a multilayer tubular structure (MLT) as defined above, in which the barrier layer (1) is an EVOH layer and the second barrier layer (5) is a fluoropolymer layer, the fluoropolymer being in particular of the ETFE, EFEP or CPT type.

[0131] Advantageously, in the multilayer tubular structure (MLT) defined above, the polyamide of the outer layer (3) is a polyamide selected from B or C defined above, in particular PA11, PA12, PA610, PA612 or PA1012, the corresponding copolyamides and blends of said polyamides or copolyamides, the polyamides obtained from lactams being advantageously washed.

[0132] Various structural embodiments In another embodiment, the present invention relates to a multi-layer tubular structure (MLT) as defined above, wherein at least one of layers (2), (3), (3'), (4) and (4') comprises at least one impact modifier and / or at least one additive.

[0133] It is very clear that the impact modifiers or additives are not plasticizers.

[0134] Advantageously, layers (2) and (3) contain at least one impact modifier and / or at least one additive.

[0135] Advantageously, layers (2), (3) and (3') contain at least one impact modifier and / or at least one additive.

[0136] Advantageously, layers (2), (3), (3') and (4') contain at least one impact modifier and / or at least one additive.

[0137] Advantageously, layers (2), (3), (3'), (4) and (4') comprise at least one impact modifier and / or at least one additive.

[0138] In another embodiment, the invention relates to a multi-layer tubular structure (MLT) as defined above, wherein the structure comprises three layers in the order (3) / / (1) / / (2), and wherein layers (3) and / or (2) do not comprise more than 1.5% by weight of plasticizer, relative to the total weight of the composition of each layer; in particular, layers (3) and / or (2) do not comprise a plasticizer.

[0139] In another embodiment, the invention relates to a multi-layer tubular structure (MLT) as defined above, wherein the structure comprises four layers in the order (3') / / (3) / / (1) / / (2), wherein layer (3') is as defined above, and wherein layers (2) and / or (3) do not comprise more than 1.5% by weight of plasticizer, relative to the total weight of the composition of each layer; in particular, layers (2) and / or (3) do not comprise a plasticizer.

[0140] In another embodiment, the present invention relates to a multi-layer tubular structure (MLT) as defined above, wherein the structure comprises five layers in the following order: (3') / / (3) / / (1) / / (5) / / (2), where layer (1) is an EVOH layer, layer (5) is a PPA layer, and layer (2) does not contain more than 1.5 wt. % of a plasticizer, based on the total weight of the composition of each layer; in particular, layer (2) does not contain a plasticizer and layers (3) and (3') contain a plasticizer; or (3') / / (3) / / (1) / / (2) / / (5), wherein layer (1) is an EVOH layer, layer (5) is a PPA layer, and layer (2) does not contain more than 1.5% by weight of a plasticizer, based on the total weight of the composition of each layer; in particular, layer (2) does not contain a plasticizer, and layers (3) and (3') contain a plasticizer; or (3) / / (4') / / (1) / / (4) / / (2), wherein layer (3) is as defined in claim 3 and layers (2) and (4) do not contain more than 1.5% by weight of plasticizer, relative to the total weight of the composition of each layer; in particular layers (2) and / or (4) do not contain a plasticizer; layer (4') contains a plasticizer; in particular layer (4') does not contain a plasticizer.

[0141] According to another embodiment, the present invention relates to a multi-layer tubular structure (MLT) as defined above, wherein the structure comprises layers in the following order: (3') / / (3) / / (4') / / (1) / / (4) / / (2), wherein layers (3) and (3') are as defined above and layers (2) and (4) do not contain more than 1.5% by weight of plasticizer, relative to the total weight of the composition of each layer; in particular layers (2) and / or (4) do not contain a plasticizer; layer (4') contains a plasticizer; in particular layer (4') does not contain a plasticizer.

[0142] In particular, layer (3') of said 6-layer structure is plasticized, said plasticizer being present in particular in a proportion of 1.5% to 15% by weight relative to the total weight of the composition of said layer; preferably, the thickness of layer (3') corresponds to at most 20% of the total thickness of the tubular structure, in particular at most 200 μm; in particular, layer (3') is the outermost layer and the only layer that is plasticized, layer (3) or layers (3) being free of plasticizer.

[0143] According to another aspect, the invention relates to a multi-layer structure as defined above, characterized in that it comprises polyamide connectors at one and / or the other of its ends, said connectors being welded to said structure.

[0144] The welding can be performed, for example, using a laser.

[0145] the polyamides are selected from the aliphatic polyamides defined above, and semi-aromatic polyamides, in particular semi-aromatic polyamides of formula X / YAr as described in EP 1 505 099 A1, in particular semi-aromatic polyamides of formula A / XT, in which A is selected from units resulting from amino acids, units resulting from lactams and units corresponding to the formula (Ca diamine).(Cb diacid), in which a represents the number of carbon atoms of the diamine and b represents the number of carbon atoms of the diacid, a and b each being between 4 and 36, advantageously between 9 and 18, (Ca diamine) units selected from linear or branched aliphatic diamines, cycloaliphatic diamines and alkylaromatic diamines, and (Cb diacid) units selected from linear or branched aliphatic diacids, cycloaliphatic diacids and aromatic diacids; XT represents units resulting from the polycondensation of a Cx diamine with terephthalic acid, x representing the number of carbon atoms of the Cx diamine, x being between 5 and 36, advantageously between 9 and 18, in particular polyamides of formula A / 5T, A / 6T, A / 9T, A / 10T or A / 11T, A being as defined above, in particular PA MPMDT / 6T, PA11 / 10T, PA 5T / 10T, PA 11 / BACT, PA 11 / 6T / 10T, PA MXDT / 10T, PA MPMDT / 10T, PA BACT / 10T, PA BACT / 6T, PA BACT / 10T / 6T, PA 11 / BACT / 6T, PA 11 / MPMDT / 6T, PA 11 / MPMDT / 10T, PA 11 / BACT / 10T, PA The polyamide is selected from PA 11 / MXDT / 10T, or PA 11 / 5T / 10T.

[0146] T corresponds to terephthalic acid, MXD corresponds to m-xylylenediamine, MPMD corresponds to methylpentamethylenediamine, and BAC corresponds to bis(aminomethyl)cyclohexane.

[0147] In one embodiment, PA12 is excluded from the aliphatic polyamides that make up the connector.

[0148] In another embodiment, the aliphatic polyamide of the connector is selected from PA6, PA66, PA6 / 66, PA11, PA610, PA612, or PA1012, in particular PA11.

[0149] In one embodiment, the connector is made from the polyamide composition defined above, which is a fiber-filled composition.

[0150] In one embodiment, the fibers are of inorganic, organic, or vegetable origin.

[0151] Among the fibres of inorganic origin, mention may be made, for example, of carbon fibres, glass fibres, basalt or basalt-based fibres, silica fibres or silicon carbide fibres. Among the fibres of organic origin, mention may be made, for example, of fibres based on thermoplastic or thermosetting polymers, such as semi-aromatic polyamide fibres, aramid fibres or polyolefin fibres.

[0152] Advantageously, the fibres are glass and / or carbon fibres.

[0153] According to another aspect, the present invention relates to the use of a multi-layer tubular structure (MLT) as defined above for transporting hydrogen. EXAMPLES

[0154] The present invention will now be described in more detail by the following non-limiting examples. The following compositions were prepared according to techniques well known to those skilled in the art for forming the inner layer (2) of the structures of the present invention (Table 1). TIFF2024536101000002.tif40170

[0155] I1 to I2: Compositions of the Present Invention C1~C2: Comparative composition PA11: PA11 is a polyamide 11 with Mn (number average molecular weight) of 45,000. Melting point 190°C, enthalpy of fusion 56 J / g. PA11 / 10T: Rilsan HT (Arkema) Plasticizer: BBSA (n-butylbenzenesulfonamide) Impact modifier: Lotader® 4700 (50%) + Lotader® AX8900 (25%) + Lucalene® 3110 (25%) Additives: Stabilizers

[0156] The following structures were produced by extrusion: The multi-layer tubes are produced by co-extrusion using a McNeil multi-layer extrusion industrial line equipped with five extruders connected to a multi-layer extrusion head with a spiral mandrel.

[0157] The screw used is a single extrusion screw with a screw profile suitable for polyamides. In addition to the five extruders and the multi-layer extrusion head, the extrusion line includes: · a die punch assembly located at the end of the coextrusion head; the inner diameter of the die and the outer diameter of the punch are selected as a function of the structure to be produced and the material from which it is made, as well as the size of the tube and the line speed; A vacuum tank with adjustable vacuum level, in which water, usually at 20°C, circulates, into which the gauges are immersed and the tubes can be formed to their final dimensions. The gauge diameter is appropriate to the dimensions of the tube to be produced, typically 8.5-10 mm for a tube with an outer diameter of 8 mm and a thickness of 1 mm; A series of cooling tanks in which water is maintained at approximately 20°C and allows cooling of the tubes along their path from the head to the drawbench; ·Diameter measuring instrument; Draw bench.

[0158] A five-extruder setup is used to produce tubes ranging from 2 to 5 layers, with several extruders fed with the same material for structures with fewer than five layers.

[0159] For structures containing six layers, an additional extruder is connected and a spiral mandrel is added to the existing head for the purpose of producing the inner layer in contact with hydrogen.

[0160] Before testing, ensure that the extrusion material has a residual moisture content of less than 0.08% before being extruded to provide the best properties and good extrusion quality for the tube. If this is not the case, an additional step is taken, usually drying the material in a vacuum dryer at 80°C overnight, before testing.

[0161] Tubes meeting the characteristics described in this patent application are removed after the extrusion parameters have stabilized, so that the tube's target dimensions do not change over time. The diameter is monitored by a laser diameter gauge installed at the end of the line.

[0162] Typically the line speed is usually 20 m / min. It typically varies between 5 and 100 m / min.

[0163] As known to those skilled in the art, the extruder screw speed depends on the layer thickness and the screw diameter.

[0164] Generally, the temperatures of the extruder and equipment (heads and connectors) must be adjusted to be sufficiently higher than the melting point of the composition under consideration so that the composition remains in a molten state and prevents it from solidifying and blocking the machine.

[0165] The tubular structures were tested for various parameters (Table 2).

[0166] The amount of extractables was determined and the barrier properties were evaluated.

[0167] The content of extractables, measured by contact with alcohol-containing gasoline ("power washing"), makes it possible to simulate the use of an H2 transport pipe over several years. The procedure used is described in Table 3.

[0168] Table 3 shows the tests used and the classification of results. TIFF2024536101000003.tif255170TIFF2024536101000004.tif56170TIFF2024536101000005.tif80170

[0169] Measurement of the permeability to gasoline (bio-gasoline barrier) is determined at 0°C according to the gravimetric method using CE10: isooctane / toluene / ethanol = 45 / 45 / 10 vol.%.

[0170] The instantaneous transmittance during the induction period is zero, and then gradually increases to an equilibrium value, which corresponds to the transmittance value under continuous operating conditions. This value obtained under continuous operating conditions is considered to be the permeability of the material.

[0171] The contaminants extracted into hydrogen from the various inner layers of the multilayer structure made from the above composition were quantified according to standard CSA / ANSI CHMC 2:19: Multilayer structure with an airtight layer based on composition I1: <0.5% Multilayer structure with an airtight layer based on composition I2: <0.5% Multilayer structure with an airtight layer based on composition I3: <0.5% Multilayer structure with an airtight layer based on composition I4: <0.5% Multilayer structure with an airtight layer based on composition I5: <0.5% Multilayer structure with an airtight layer based on composition C1: >3% Multilayer structure with an airtight layer based on composition C2: >3%

[0172] composition PA12-TL: represents a composition based on polyamide 12 with Mn (number average molecular weight) 35,000, containing 6% plasticizer BBSA (benzyl butyl sulfonamide), 6% anhydride-functionalized EPR Exxelor VA1801 (Exxon), and 1.2% organic stabilizer consisting of 0.8% phenol Lowinox 44B25 (Great Lakes), 0.2% phosphorous acid Irgafos 168 (Ciba), and 0.2% UV stabilizer Tinuvin 312 (Ciba). The melting point of this composition is 175°C.

[0173] PA12-NoPlast = PA12-TL without plasticizer (the latter is replaced by the same % of PA12).

[0174] PA11-TL: represents a composition based on polyamide 11 with Mn (number average molecular weight) 29,000, containing 5% plasticizer BBSA (benzyl butyl sulfonamide), 6% impact modifier of ethylene / ethyl acrylate / anhydride type in a weight ratio of 68.5 / 30 / 1.5 (MFI 6 at 190°C, 2.16 kg), and 1.2% organic stabilizer (consisting of 0.8% phenol Lowinox 44B25 (Great Lakes), 0.2% phosphorous acid Irgafos 168 (Ciba), and 0.2% UV stabilizer Tinuvin 312 (Ciba)). The melting point of this composition is 185°C.

[0175] PA11-NoPlast = PA11-TL without plasticizer (the latter is replaced by PA11) PA610-TL = PA610 + 12% impact modifier EPR1 + organic stabilizer + 10% plasticizer PA610-NoPlast = PA610-TL without plasticizer (the latter is replaced by PA610) PA612-TL = PA612 + 12% impact modifier EPR1 + organic stabilizer 9 percent plasticizer PA612-NoPlast = PA612-TL without plasticizer (the latter is replaced by PA612) PA6-TL = PA6 + 12% impact modifier EPR1 + organic stabilizer 12 percent plasticizer PA6-NoPlast = PA6-TL without plasticizer (the latter is replaced by PA6) PA12: Polyamide 12 with Mn (number average molecular weight) of 35,000. The melting point is 178°C and the enthalpy of fusion is 54 kJ / m 2 It is. PA11: Polyamide 11 with Mn (number average molecular weight) of 29,000. The melting point is 190°C and the fusion enthalpy is 56 kJ / m 2 It is. PA610: Polyamide 6.10 with Mn (number average molecular weight) of 30,000. The melting point is 223°C and the enthalpy of fusion is 61 kJ / m 2 It is. PA612: Polyamide 6.12 with Mn (number average molecular weight) of 29,000. The melting point is 218°C and the enthalpy of fusion is 67kJ / m 2 It is. PA6: Polyamide 6 with Mn (number average molecular weight) of 28,000. The melting point is 220°C and the enthalpy of fusion is 68kJ / m 2 It is. EPR1: EPR functionalized with anhydride functional reactive groups (0.5% to 1% by weight) of type Exxellor VA1801 from Exxon, MFI (230°C, 10 kg) 9.

[0176] Organic Stabilizer = 1.2% organic stabilizer consisting of 0.8% phenol (Lowinox 44B25, Great Lakes), 0.2% phosphorous acid (Irgafos 168, Ciba), and 0.2% UV stabilizer (Tinuvin 312, Ciba).

[0177] Plasticizer = BBSA (benzyl butyl sulfonamide)

[0178] coPA612-6T-NoPlast = 20 mol% of 6.T (hence 80 mol% of 6.12) (this coPA has MFI 235°C, 5kg = (melting point = 200°C)) + 20% EPR1 + organic stabilizer, coPA6.12 / 6.T

[0179] PPA10T = coPA10.T / 6T with molar ratio 60 / 40, melting point 280°C + 18% EPR1 + organic stabilizer

[0180] PA11cond-NoPlast = PA11 with Mn15,000 + 9% EPR1 + 22% Ensaco 200 type carbon black

[0181] Tie = composition based on 43.8% PA612 (defined elsewhere), 25% PA6 (defined elsewhere), 20% impact modifier of EPR1 type, 1.2% organic stabilizer (consisting of 0.8% phenolic Lowinox 44B25 (Great Lakes), 0.2% phosphorous acid Irgafos 168 (Ciba) and 0.2% UV stabilizer Tinuvin 312 (Ciba)) and 10% plasticizer BBSA (benzyl butyl sulfonamide).

[0182] Tie-NoPlast = composition based on 48.8% PA612 (defined elsewhere), 30% PA6 (defined elsewhere), 20% impact modifier of EPR1 type and 1.2% organic stabilizer (consisting of 0.8% phenolic Lowinox 44B25 (Great Lakes), 0.2% phosphorous acid Irgafos 168 (Ciba) and 0.2% UV stabilizer Tinuvin 312 (Ciba)).

[0183] Tie2 = composition based on 43.8% PA610 (defined elsewhere), 25% PA6 (defined elsewhere), 20% impact modifier of EPR1 type, 1.2% organic stabilizer (consisting of 0.8% phenolic Lowinox 44B25 (Great Lakes), 0.2% phosphorous acid Irgafos 168 (Ciba) and 0.2% UV stabilizer Tinuvin 312 (Ciba)) and 10% plasticizer BBSA (benzyl butyl sulfonamide).

[0184] Tie2-NoPlast = composition based on 48.8% PA610 (defined elsewhere), 30% PA6 (defined elsewhere) and 20% impact modifier of EPR1 type, and 1.2% organic stabilizer (consisting of 0.8% phenolic Lowinox 44B25 (Great Lakes), 0.2% phosphorous acid Irgafos 168 (Ciba) and 0.2% UV stabilizer Tinuvin 312 (Ciba)).

[0185] EVOH = EVOH with 32% ethylene, EVAL FP101B type (Eval)

[0186] EVOH24 = EVOH with 24% ethylene, EVAL M100B type (Eval)

[0187] EVOHhi = EVOH with 27% ethylene and impact modifier EVAL LA170B type (Eval)

[0188] PPA10T / 6T = 40 mol% 6.T (MFI = 8 at 300 °C, 5 kg, melting point 280 °C) + 15% EPR1 + coPA10.T / 6.T with organic stabilizer

[0189] EFEPc = functionalized conductive EFEP of Neoflon RP5000AS type (Daikin)

[0190] Tie PA610+PA6. Shows a composition based on PA612 (Mn 29,000, as defined elsewhere), 36% PA6 (Mn 28,000, as defined elsewhere) and 1.2% organic stabilizer consisting of 0.8% phenolic Lowinox 44B25 (Great Lakes), 0.2% phosphorous Irgafos 168 (Ciba), and 0.2% UV stabilizer Tinuvin 312 (Ciba).

[0191] The structures presenting a plasticizer-free layer located under the barrier and in particular in contact with hydrogen, show excellent results with respect to the extractables tests, results that are much better than the counterexamples in which the layer in contact with hydrogen is plasticized.

Claims

1. A multi-layer tubular structure (MLT) intended for transporting hydrogen, comprising, from the outside to the inside, at least one barrier layer (1) and at least one inner layer (2) located below the barrier layer, said inner layer (2), or the combination of layer (2) with other optional layers located below the barrier layer, comprises, on average, 0 to 1.5 wt. % of a plasticizer, relative to the total weight of the composition of layer (2), or the total weight of the combination of the composition of layer (2) with other optional layers located below the barrier layer; the inner layer (2) exhibits an extractive content of less than or equal to 3% by weight, in particular less than 2% by weight, of the sum of the components of the composition, determined according to standard CSA / ANSI CHMC 2:19, The inner layer (2) mainly comprises at least one aliphatic type polyamide or consists of more than 75% aliphatic units, the aliphatic polyamide being - A polyamide having the formula C Ａ wherein the average number of carbon atoms per nitrogen atom is from 4 to 8.5, preferably from 4 to 7; - Polyamides of the type indicated by B, Ｂ wherein the average number of carbon atoms per nitrogen atom is from 7 to 10, preferably from 7.5 to 9.5; - Polyamides of the formula C, Ｃ wherein the average number of carbon atoms per nitrogen atom is from 9 to 18, preferably from 10 to 18; is selected from However, when the inner layer (2) contains at least three polyamides, at least one of the polyamides A, B, and C is excluded. Multilayer tubular structure (MLT).

2. 2. A multilayer tubular structure (MLT) according to claim 1, wherein the barrier layer is selected from an EVOH layer, a fluoropolymer layer, in particular a PVDF layer, and a PPA layer.

3. 2. The multi-layer tubular structure (MLT) of claim 1, wherein the inner layer (2), or the layer (2) and each of the other optional layers located below the barrier layer, are plasticizer-free.

4. there is at least one further outer layer (3) located on the barrier layer, said outer layer (3) mainly comprising at least one polyamide of aliphatic type or consisting of more than 75% aliphatic units, in particular said aliphatic polyamide exhibiting an average number of carbon atoms per nitrogen atom of 9.5 to 18, preferably 11 to 18, The multi-layer tubular structure (MLT) according to claim 1.

5. 5. A multilayer tubular structure (MLT) according to claim 4, wherein the outer layer (3) comprises from 0% to 15% of plasticizer relative to the total weight of the composition of said layer (3), or the combined outer layers comprise on average from 0% to 5% of plasticizer.

6. 5. A multilayer tubular structure (MLT) according to claim 4, wherein there is present at least one second outer layer (3') located on the barrier layer, preferably on layer (3), said layer (3') being plasticized, said plasticizer being present in particular in a proportion of 1.5% to 15% by weight relative to the total weight of the composition of said layer; preferably the thickness of said layer (3') represents at most 20% of the total thickness of the tubular structure, in particular at most 200 μm.

7. 7. A multi-layer tubular structure (MLT) according to claim 6, wherein the layer (3') is the outermost layer and is the only layer that is plasticized, and the layer(s) (3) are plasticizer-free.

8. at least one layer (4) is present, said layer (4) not comprising more than 15% by weight of plasticizer, preferably not more than 1.5% by weight of plasticizer, relative to the total weight of the constituents of said layer (4); advantageously, layer (4) does not comprise a plasticizer, The layer (4) mainly comprises at least one aliphatic type polyamide or consists of more than 75% aliphatic units, the aliphatic polyamide being - A polyamide having the formula C Ａ wherein the average number of carbon atoms per nitrogen atom is from 4 to 8.5, preferably from 4 to 7; - Polyamides of the type indicated by B, Ｂ wherein the average number of carbon atoms per nitrogen atom is from 7 to 10, preferably from 7.5 to 9.5; - Polyamides of the formula C, Ｃ wherein the average number of carbon atoms per nitrogen atom is from 9 to 18, preferably from 10 to 18; is selected from However, if the layer (4) comprises at least three polyamides, at least one of the polyamides A, B, and C is excluded; or said layer (4) being a bonding layer, the thickness of which corresponds to a maximum of 15% of the (MLT) structure; The layer (4) is located between the barrier layer (1) and the inner layer (2) and / or between the outer layer (3) and the barrier layer (1), A multi-layer tubular structure (MLT) according to claim 4.

9. There is a layer (4') present, said layer (4') mainly comprising at least one polyamide of aliphatic type or consisting of more than 75% aliphatic units, said aliphatic polyamide being - A polyamide having the formula C Ａ wherein the average number of carbon atoms per nitrogen atom is from 4 to 8.5, preferably from 4 to 7; - Polyamides of the type indicated by B, Ｂ wherein the average number of carbon atoms per nitrogen atom is from 7 to 10, preferably from 7.5 to 9.5; - Polyamides of the formula C, Ｃ wherein the average number of carbon atoms per nitrogen atom is from 9 to 18, preferably from 10 to 18; is selected from However, if the layer (4') comprises at least three polyamides, at least one of the polyamides A, B, and C is excluded, or said layer (4') is a bonding layer, the thickness of which corresponds to a maximum of 15% of the (MLT) structure; The at least one polyamide of the layer (4') can be the same as or different from the polyamide of the layer (4); The layer (4') is located between the outer layer (3) and the barrier layer (1), and the tie layer (4) is located between the barrier layer (1) and the inner layer (2). A multi-layer tubular structure (MLT) according to claim 8.

10. 5. The multilayer tubular structure (MLT) according to claim 4, wherein the polyamide of the inner layer (2) or the polyamide of the outer layer (3) is entirely aliphatic; preferably the polyamide of the inner layer (2) and the polyamide of the outer layer (3) are entirely aliphatic polyamides.

11. 5. The multilayer tubular structure (MLT) according to claim 4, wherein a second barrier layer (5) is present, said second barrier layer (5) being located below the first barrier layer (1) with or without being adjacent to said barrier layer (1).

12. 3. The multi-layer tubular structure (MLT) of claim 2, wherein the barrier layer is an EVOH layer containing up to 27% ethylene.

13. 3. The multi-layer tubular structure (MLT) of claim 2, wherein the barrier layer is an EVOH layer containing an impact modifier.

14. 12. A multilayer tubular structure (MLT) according to claim 11, wherein the barrier layer (1) is an EVOH layer and the second barrier layer (5) is a PPA or fluoropolymer layer, the fluoropolymer being in particular of the ETFE, EFEP or CPT type.

15. 2. The multilayer tubular structure (MLT) according to claim 1, wherein the polyamide of the inner layer (2) is a polyamide-based composition selected from A, B or C according to claim 1, in particular PA6, PA66, PA6 / 66, PA11, PA610, PA612 or PA1012, corresponding copolyamides and blends of said polyamides or copolyamides, the polyamides obtained from lactams being advantageously washed.

16. 5. The multilayer tubular structure (MLT) according to claim 4, wherein the polyamide of the outer layer (3) is a polyamide selected from B or C according to claim 1, in particular PA11, PA12, PA610, PA612 or PA1012, corresponding copolyamides and blends of said polyamides or copolyamides, the polyamides obtained from lactams being advantageously washed.

17. 2. A multilayer tubular structure (MLT) according to claim 1, wherein the polyamide of the inner layer (2) is a polyamide-based composition selected from A, B or C according to claim 1, in particular PA6, PA66, PA6 / 66, PA11, PA610, PA612 or PA1012, the corresponding copolyamides and blends of said polyamides or copolyamides, polyamides obtained from lactams being advantageously washed, and the polyamide of the outer layer (3) is a polyamide selected from B or C according to claim 1, in particular PA11, PA12, PA610, PA612 or PA1012, the corresponding copolyamides and blends of said polyamides or copolyamides, polyamides obtained from lactams being advantageously washed.

18. 2. A multilayer tubular structure (MLT) according to claim 1, wherein the polyamide of the inner layer (2) or at least one of the polyamides of the other layers (2) is a conductive polyamide.

19. 10. Multilayer tubular structure (MLT) according to claim 9, wherein the polyamide of layers (4) and / or (4') is selected from the following binary blends: PA6 and PA12, PA6 and PA612, PA6 and PA610, PA12 and PA612, PA12 and PA610, PA1010 and PA612, PA1010 and PA610, PA1012 and PA612, PA1012 and PA610, and the following ternary blends: PA6, PA610, and PA12; PA6, PA612, and PA12; PA6, PA614, and PA12.

20. 10. The multi-layer tubular structure (MLT) of claim 9, wherein at least one of the layers (2), (3), (4), and (4') comprises at least one impact modifier and / or at least one additive.

21. 5. A multilayer tubular structure (MLT) according to claim 4, wherein the structure comprises three layers in the order (3) / / (1) / / (2), and wherein layers (3) and / or (2) do not comprise more than 1.5% by weight of plasticizer, relative to the total weight of the composition of each layer; in particular, layers (3) and / or (2) do not comprise any plasticizer.

22. The structure comprises four layers in the order (3') / / (3) / / (1) / / (2), with layer (3') being 7. A multilayer tubular structure (MLT) according to claim 6, wherein layers (2) and / or (3) do not contain more than 1.5% by weight of plasticizer, relative to the total weight of the composition of each layer; in particular, layers (2) and / or (3) do not contain any plasticizer.

23. The structure has five layers: (3') / / (3) / / (1) / / (5) / / (2) in this order, where layer (1) is an EVOH layer and layer (5) is a PPA layer, and layer (2) does not contain more than 1.5 wt. % of a plasticizer, based on the total weight of the composition of each layer; in particular, layer (2) does not contain a plasticizer, and layers (3) and (3') contain a plasticizer; or (3') / / (3) / / (1) / / (2) / / (5) in this order, where layer (1) is an EVOH layer and layer (5) is a PPA layer, and layer (2) does not contain more than 1.5 wt. % of a plasticizer, based on the total weight of the composition of each layer; in particular, layer (2) does not contain a plasticizer, and layers (3) and (3') contain a plasticizer; or (3) / / (4') / / (1) / / (4) / / (2) in that order, wherein layer (3) is as defined in claim 4, and layers (2) and (4) do not contain more than 1.5% by weight of plasticizer, relative to the total weight of the composition of each layer; in particular, layers (2) and / or (4) do not contain a plasticizer, and layer (4') contains a plasticizer. A multi-layer tubular structure (MLT) according to claim 11.

24. The structure is layered, 10. A multilayer tubular structure (MLT) according to claim 8, comprising layers (3') / / (3) / / (4') / / (1) / / (4) / / (2) in that order, wherein layers (3) and (3') are as defined in claim 4 or 6, and layers (2) and (4) do not contain more than 1.5 wt. % of a plasticizer, relative to the total weight of the composition of each layer; in particular, layers (2) and / or (4) do not contain a plasticizer, and layer (4') contains a plasticizer.

25. 10. The multi-layer structure of claim 1, including polyamide connectors at one and / or the other of the ends, said connectors being welded to the structure.

26. 26. The structure of claim 25, wherein the polyamide of the connector is selected from PA6, PA66, PA6 / 66, PA11, PA610, PA612, or PA1012.

27. 10. Use of the multi-layer tubular structure (MLT) according to claim 1 for transporting hydrogen.