Composition of polyamide and graphene

Abstract

The invention relates to a composition comprising, relative to the total weight of the composition: at least 50% by weight of at least one polyamide having a C / N atomic ratio greater than 6.5; and from 0.05 to 20% of at least one graphene, graphene being distinct from graphene oxide. The invention also relates to the use of this composition for the preparation of monolayer or multilayer structures for the storage, transport, and distribution of fluids, particularly fluids for transport vehicles. Figure: none

Description

Title of the invention: Composition of polyamide and graphene Field of invention

[0001] The present invention relates to polyamide and graphene compositions for the manufacture of single-layer or multi-layer structures, in particular for applications in the transport, distribution or storage of fluids. Technical background

[0002] The supply of fluid to transport vehicles, for example motor vehicles, trains, trucks, etc., in particular the supply of fuel for thermal vehicles, the supply of cooling fluid, the supply of hydrogen to fuel cells, etc., requires the presence of storage, distribution and transport structures of the tank, pipe, etc. type.

[0003] These structures must fulfill two essential functions: Waterproofing or low permeability to limit fluid losses; Mechanical resistance (in traction and shock).

[0004] Furthermore, it is essential that the fluid does not carry, or carries very little, contaminants that would come from the storage, distribution or transport structures. Thus, it is essential that the compositions forming said storage, distribution or transport structures have the lowest possible extractable content.

[0005] There is therefore a real need to provide compositions making it possible to prepare structures for storing, distributing and / or transporting fluid, in particular fluid used in transport vehicles, having, in addition to good mechanical strength properties: Low permeability to limit fluid losses; and / or Low extractable rate.

[0006] There is also a need to provide such compositions for preparing structures for storing, distributing and / or transporting fluid, furthermore having: Good fire resistance, in particular the structure is fire resistant with a V0, VI or V2 result on the UL94 test (IEC 60695-11-10); and / or Good thermal and / or electrical conductivity; and / or A good compromise between low density and good mechanical resistance. Summary of the invention

[0007] The invention relates firstly to a composition comprising, relative to the total weight of the composition: - At least 50% by weight of at least one polyamide having a C / N atomic ratio greater than 6.5; - From 0.05 to 20% of at least one graphene, graphene being different from graphene oxide.

[0008] In one embodiment, the composition according to the invention further comprises: - up to 40% by weight, relative to the weight of the composition, of at least one impact modifier; and / or - Up to 5% by weight of at least one additive; and / or - Up to 14% by weight of at least one plasticizer; and / or - From 5 to 49% by weight of short reinforcing fibers.

[0009] In one embodiment, the polyamide of the composition according to the invention is: - An aliphatic polyamide resulting from polycondensation: • at least one amino acid in C6 to C18, preferably in C10 to C18, even more preferably in C10 to C12; or • at least one C6 to C18 lactam, preferably C10 to C18, even more preferably C10 to C12; or • at least one aliphatic diamine Xa in C4-C36, preferably C5-C18, preferably C5-C12, more preferably C10-C12 with at least one aliphatic diacid Yb in C4-C36, preferably C6-C18, preferably C6-C12, more preferably C10-C12; or - A semi-aromatic polyamide of formula XAr or Ar'Y in which XAr denotes a unit obtained from the polycondensation of a diamine X and an aromatic dicarboxylic acid Ar, the diamine X being C6-C36, preferably C6-C18, preferably C6-C12, more preferably C10-C12, Ar'Y denotes a unit obtained from the polycondensation of an aromatic diamine Ar' and an aliphatic dicarboxylic acid Y, the aromatic diamine Ar' being for example chosen from MXD (metaxylylene diamine) and PXD (paraxylylene diamine).

[0010] Preferably, the polyamide is: - An aliphatic polyamide chosen from PA610, PA612, PA 1010, PA1012, PA1014, PA1212, PA1214, PAU, PA12, preferably PA610, PA1010, PA1012, PA1014, PA1212, PA1214, PAU; preferably PAU, PA 12, preferably PA11 - A semi-aromatic polyamide chosen from PA 10T / TMDT, PA 1.3BACT / 6T / 10T, PA 1.3BACT / 6T, PA 12 / BI / BT, PA 12 / BI, PA TMDT, PA 10T / BACT, PA MXD6 / MXDT, PA 9T, PA 10T, PA MXD10 / MXDT, PA PXD6 / PXDT, PA PXD10 / PXDT, PA MXDT / BACT, The PA MXD10 / BACT.

[0011] In one embodiment, the impact modifier is chosen from functionalized or non-functionalized polyolefins or PEBAs.

[0012] The present invention also relates to single-layer or multi-layer structures in which the layer in the case of the single-layer structure or at least one of the layers in the case of the multi-layer structure is formed in whole or in part from the composition according to the invention.

[0013] In one embodiment, these structures are tubular structures.

[0014] In another embodiment, these structures are reservoirs.

[0015] The present invention also relates to the use of said structures for the transport, distribution and storage of a fluid.

[0016] In one embodiment, the fluid is hydrogen.

[0017] In another embodiment, the fluid is a fuel.

[0018] The present invention also relates to the use of a composition according to the invention for the manufacture of a single-layer or multi-layer structure by injection, extrusion, extrusion-blow molding or rotational molding, preferably by extrusion.

[0019] The present invention also relates to the use of 0.05 to 20% by weight of at least one graphene, said graphene not being a graphene oxide, in a composition comprising, relative to the total weight of the composition: - At least 50% by weight of at least one polyamide having a C / N atomic ratio greater than 6.5;

[0020] to obtain an extractable rate of less than 4 g / m2, preferably less than 3 g / m2 according to standard TL52712.

[0021] The present invention also relates to the use of 0.05 to 20% by weight of at least one graphene, said graphene not being a graphene oxide, in a composition comprising, relative to the total weight of the composition: - At least 50% by weight of at least one polyamide having a C / N atomic ratio greater than 6.5;

[0022] the percentages being given relative to the total weight of the composition,

[0023] to obtain a lower extractable rate than that obtained for the same composition free of graphene, in the graphene was replaced by the same amount of polyamide in the composition.

[0024] The present invention also relates to the use of 0.05 to 20% by weight of at least one graphene, said graphene not being a graphene oxide, in a composition comprising, relative to the total weight of the composition: - At least 50% by weight of at least one polyamide having a C / N atomic ratio greater than 6.5;

[0025] the percentages being given relative to the total weight of the composition,

[0026] to obtain a fluid permeability lower than that obtained for the same composition free of graphene, in the graphene was replaced by the same quantity of the polyamide of the composition.

[0027] The present invention also relates to a method of manufacturing a single-layer or multi-layer structure according to the invention, characterized in that it comprises a step of manufacturing a sealing layer by injection, extrusion, extrusion-blow molding or rotational molding.

[0028] In a particularly advantageous manner, the inventors have shown that the combination of polyamide with graphene makes it possible to improve in particular the mechanical resistance while limiting the density of the structures for storage, distribution and / or transport of fluid prepared from these compositions. Detailed description

[0029] The invention is now described in more detail and in a non-limiting manner in the following description.

[0030] Unless otherwise indicated, all percentages are mass percentages.

[0031] In this text, the quantities indicated for a given species may apply to this species according to all its definitions (as mentioned in this text), including the more restricted definitions. Composition Polyamide

[0032] Said at least one polyamide is a polyamide having a C / N ratio greater than 6.5, preferably greater than 8, advantageously greater than 9.

[0033] The composition according to the invention comprises at least 50% by weight, preferably from 70 to 99.5% by weight, more preferably from 90 to 99% by weight, of at least one polyamide having a C / N ratio greater than 6.5, preferably greater than 8, advantageously greater than 9, relative to the total weight of the composition.

[0034] The polyamide can be aliphatic or semi-aromatic.

[0035] Preferably the polyamide is an aliphatic polyamide.

[0036] The nomenclature used to define polyamides is described in ISO 1874-1:2011 "Plastics - Polyamide (PA) materials for molding and extrusion - Part 1: Designation" and is well known to those skilled in the art.

[0037] The term “polyamide” according to the invention designates both a homopolyamide and a copolyamide.

[0038] Advantageously, said polyamide is semi-crystalline.

[0039] The expression “semi-crystalline polyamide” within the meaning of the invention throughout the description designates polyamides which have a melting temperature (Tf) and an enthalpy of fusion AH > 25 J / g, in particular > 40 J / g, in particular > 45 J / g, as well as than a glass transition temperature (Tg) as determined by DSC according to ISO 11357-1:2016 and ISO 11357-2 and 3:2013, at a heating rate of 20K / min.

[0040] The number-average molecular mass Mn of said semi-crystalline polyamide is preferably in a range from 10,000 to 85,000 g / mol, in particular from 10,000 to 60,000 g / mol, preferably from 10,000 to 50,000 g / mol, even more preferably from 12,000 to 50,000 g / mol. The number-average molecular mass Mn can be measured by any method known to those skilled in the art and in particular The number-average (Mn) and weight-average (Mw) molar mass is determined by size exclusion chromatography according to ISO standards 16014-1:2012, 16014-2:2012 and 16014-3:2012 using the following conditions:

[0041] Device: Waters Alliance 2695 instrument

[0042] Solvent: hexafluoroisopropanol stabilized with 0.05M potassium trifluoroacetate

[0043] Flow rate: 1 ml / minute

[0044] Column temperature: 40°C.

[0045] Two columns in series: 1000 Â PFG and 100 Â PFG (PPS)

[0046] Sample concentration: 1 g / L (dissolution at room temperature for 24 h)

[0047] Filtration of samples using a syringe fitted with an ACRODISC PTFE filter, diameter 25mm, porosity 0.2 pm

[0048] Injection volume: lOOpl

[0049] Refractometric detection at 40°C with UV detection at 228 nm

[0050] Calibration by PMMA standards from 1,900,000 to 402 g.mol-1. Calibration curve modeled by a fifth-degree polynomial.

[0051] Said at least one polyamide when it is aliphatic is obtained from the polycondensation of at least one lactam, or from the polycondensation of at least one amino acid, or from the polycondensation of at least one diamine Xa with at least one dicarboxylic acid Yb.

[0052] When said at least one aliphatic polyamide is obtained from the polycondensation of at least one lactam, said at least one lactam may be chosen from a C6 to C18 lactam, preferably a C10 to C18 lactam, more preferably a C10 to C12 lactam. A C6 to C12 lactam is in particular caprolactam, decanolactam, undecanolactam, and lauryllactam.

[0053] When said at least one aliphatic polyamide is obtained from the polycondensation of at least one lactam, it can therefore comprise a single lactam or several lactams.

[0054] Advantageously, said at least one aliphatic polyamide is obtained from the polycondensation of a single lactam and said lactam is chosen from lauryllactam and undecanolactam, advantageously lauryllactam.

[0055] When said at least one aliphatic polyamide is obtained from the polycondensation of at least one amino acid, said at least one amino acid may be chosen from a C6 to C18 amino acid, preferably a C10 to C18 amino acid, more preferably a C10 to C12 amino acid.

[0056] A C6 to C12 amino acid is in particular 6-aminohexanoic acid, 9-aminononanoic acid, 10-aminodecanoic acid, 10-aminoundecanoic acid, 12-aminododecanoic acid and 11-aminoundecanoic acid as well as its derivatives, in particular N-heptyl-11-aminoundecanoic acid.

[0057] When said at least one aliphatic polyamide is obtained from the polycondensation of at least one amino acid, it can therefore comprise a single amino acid or several amino acids.

[0058] Advantageously, said aliphatic polyamide is obtained from the polycondensation of a single amino acid and said amino acid is chosen from 11-aminoundecanoic acid and 12-aminododecanoic acid, advantageously 11-aminoundecanoic acid.

[0059] When said at least one aliphatic polyamide is obtained from the polycondensation of at least one C4-C36, preferably C5-C18, preferably C5-C12, more preferably C10-C12, diamine Xa with at least one C4-C36, preferably C6-C18, preferably C6-C12, more preferably C10-C12, diacid Yb, then said at least one Xa diamine is an aliphatic diamine and said at least one Yb diacid is an aliphatic diacid.

[0060] The diamine may be linear or branched. Advantageously, it is linear.

[0061] Said at least one C4-C36 diamine Xa 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, eicosanediamine, docosanediamine and diamines obtained from fatty acids.

[0062] Advantageously, said at least one diamine Xa is C5-C18 and chosen from 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.

[0063] Advantageously, said at least one diamine Xa in C5 to C12, is in particular chosen from 1,5-pentamethylenediamine, 1,6-hexamethylenediamine, 1,7-heptamethylenediamine, 1,8-octamethylenediamine, 1,9-nonamethylenediamine, 1,10-decamethylenediamine, 1,11-undecamethylenediamine, 1,12-dodecamethylenediamine.

[0064] Advantageously, said at least one diamine Xa in C6 to C12, is in particular chosen from 1,6-hexamethylenediamine, 1,7-heptamethylenediamine, 1,8-octamethylenediamine, 1,9-nonamethylenediamine, 1,10-decamethylenediamine, 1,11-undecamethylenediamine, 1,12-dodecamethynediamine.

[0065] Advantageously, the diamine Xa used is C10 to C12, in particular chosen from 1,10-decamethylenediamine, 1,11-undecamethylenediamine, 1,12-dodecamethylenediamine.

[0066] Said at least one C4 to C36 dicarboxylic acid Yb 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, and diacids obtained from fatty acids.

[0067] The diacid may be linear or branched. Advantageously, it is linear.

[0068] Advantageously, said at least one dicarboxylic acid Yb 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.

[0069] Advantageously, said at least one dicarboxylic acid Yb is C6 to C12 and is chosen from adipic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid.

[0070] Advantageously, said at least one dicarboxylic acid Yb is C10 to C12 and is chosen from sebacic acid, undecanedioic acid, dodecanedioic acid.

[0071] When said aliphatic polyamide is obtained from the polycondensation of at least one diamine Xa with at least one dicarboxylic acid Yb, it can therefore comprise a single diamine or several diamines and a single dicarboxylic acid or several dicarboxylic acids.

[0072] Advantageously, said aliphatic polyamide is obtained from the polycondensation of a single diamine Xa with a single dicarboxylic acid Yb.

[0073] In one embodiment, the polyamide is aliphatic and is chosen from PA610, PA612, PA1010, PA1012, PA1014, PA1212, PA1214, PAU, the PA12.

[0074] Advantageously, it is chosen from PA612, PA 1010, PA 1012, PA 1014, PA1212, PA1214, PA11 and PA12, in particular from PAU and PA12. Advantageously, it is chosen from PA1010, PA1012, PA1014, PA1212, PA 1214, PAU, in particular the polyamide is PAU polyamide.

[0075] Preferably, the polyamide is polyamide PA11 or PA12, preferably PAU.

[0076] Said at least one semi-aromatic polyamide or polyphthalamide (PPA) may be a homopolyamide or a copolyamide.

[0077] When it is in the form of homopolyamide, it is of formula XAr or Ar'Y.

[0078] XAr denotes a unit obtained from the polycondensation of a diamine X and an aromatic dicarboxylic acid Ar, the diamine X being C6-C36, preferably C6-C18, preferably C6-C12, more preferably C10-C12.

[0079] The diamine may be linear or branched. Advantageously, it is linear.

[0080] Said at least one C6-C36 diamine X may in particular be chosen from 1,6-hexamethylenediamine, 2,2,4-trimethylhexanediamine (TMD), 1,7-heptamethylenediamine, 1,8-octamethylenediamine, 1,9-nonamethylenediamine, 1,10-decamethylenediamine, 1,11-undecamethylenediamine, 1,12-dodecamethyldiamine, 1,13-tridecamethylenediamine, 1,14-tetradecamethylenediamine, 1,16-hexadecamethylenediamine and 1,18-octadecamethylenediamine, octadecenediamine, eicosanediamine, docosanediamine and diamines obtained from fatty acids.

[0081] Advantageously, said at least one diamine X 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.

[0082] Advantageously, said at least one diamine X in C6 to C12, is in particular chosen from 1,6-hexamethylenediamine, 1,7-heptamethylenediamine, 1,8-octamethylenediamine, 1,9-nonamethylenediamine, 1,10-decamethylenediamine, 1,11-undecamethylenediamine, 1,12-dodecamethylenediamine.

[0083] Advantageously, said at least one diamine X in C6 to C12, is in particular chosen from 1,6-hexamethylenediamine, 1,7-heptamethylenediamine, 1,8-octamethylenediamine, 1,9-nonamethylenediamine, 1,10-decamethylenediamine, 1,11-undecamethylenediamine, 1,12-dodecamethylenediamine.

[0084] Advantageously, the diamine X used is C10 to C12, in particular chosen from 1,10-decamethylenediamine, 1,11-undecamethylenediamine, 1,12-dodecamethylenediamine.

[0085] The aromatic dicarboxylic acid being advantageously chosen from terephthalic acid (denoted T), isophthalic acid (denoted I), 2,5-furan dicarboxylic acid and 2,6-naphthalene dicarboxylic acid (denoted N) or mixtures thereof, in particular it is chosen from terephthalic acid (denoted T), isophthalic acid (denoted I) or mixtures thereof.

[0086] Ar'Y denotes a unit obtained from the polycondensation of an aromatic diamine Ar' and an aliphatic dicarboxylic acid Y, the aromatic diamine Ar' being for example chosen from MXD (metaxylylene diamine) and PXD (paraxylylene diamine).

[0087] MXDY denotes a unit obtained from the polycondensation of diamine metaxylylene diamine (MXD) and at least one aliphatic dicarboxylic acid Y.

[0088] PXDY denotes a unit obtained from the polycondensation of diamine paraxylylene diamine (MXD) and at least one aliphatic dicarboxylic acid Y.

[0089] Said at least one C6 to C36 dicarboxylic acid Y may be chosen from adipic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, brassylic acid, tetradecanedioic acid, pentadecanedioic acid, hexadecanedioic acid, octadecanedioic acid, and diacids obtained from fatty acids.

[0090] The diacid may be linear or branched. Advantageously, it is linear.

[0091] Advantageously, said at least one dicarboxylic acid Y is C6 to C18 and is chosen from adipic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, brassylic acid, tetradecanedioic acid, pentadecanedioic acid, hexadecanedioic acid, octadecanedioic acid.

[0092] Advantageously, said at least one dicarboxylic acid Y is C6 to C12 and is chosen from adipic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid.

[0093] Advantageously, said at least one dicarboxylic acid Y is C10 to C12 and is chosen from sebacic acid, undecanedioic acid, dodecanedioic acid.

[0094] Preferably, the semi-aromatic polyamides are chosen from PA PA PXD10 / PXDT, PA MXDT / BACT, PA MXD10 / BACT.

[0095] Preferably, the polyamide according to the invention has an inherent viscosity greater than 1.0, preferably greater than 1.2, more preferably greater than 1.4, even more preferably greater than 1.6.

[0096] The measurement of the inherent (or intrinsic) viscosity is carried out in m-cresol. The method is well known to those skilled in the art. The ISO 307:2007 standard is followed but the solvent (use of m-cresol instead of sulfuric acid), and the temperature (being 20°C), and the concentration (0.5% by mass) are changed.

[0097] In one embodiment of the invention, the polyamide used in the composition is a recycled polyamide. Graphene

[0098] The composition of the invention comprises from 0.05 to 20% by weight, preferably from 0.1 to 15% by weight, more preferably from 0.1 to 5% by weight, even more preferably from 0.1 to 2% by weight of at least one graphene, said graphene not being a graphene oxide.

[0099] In the case of an analysis of the graphene included in the composition, the physicochemical characterization of the graphene is carried out after calcination of the composition for 12 minutes at 600°C in a closed crucible placed in a muffle furnace or after dissolution of the matrix and filtration of the graphenes. The dissolution is preferably carried out in meta-cresol or hexafluoroispropanol at 25°C.

[0100] The specific surface area is measured according to the BET method as described in ISO 9277:2010.

[0101] Preferably, the graphene according to the invention has a content in number of carbon atoms, relative to the total number of atoms of the graphene (with the exception of any hydrogen atoms present in the graphene) of between 50 and 100%, preferably between 66 and 99.9%, advantageously between 90 and 99.5%, preferably the content in number of carbon atoms relative to the total number of atoms of the graphene (with the exception of any hydrogen atoms present in the graphene) is between 98 and 100%.

[0102] Preferably, the graphene according to the invention has a content in number of oxygen atoms relative to the total number of atoms of the graphene (with the exception of any hydrogen atoms present in the graphene) less than or equal to 20%, preferably less than or equal to 10%.

[0103] The determination of the ratio between the different atoms present in graphene can be carried out by elemental analysis. This method is described in the scientific article “Jianguo Song, Xinzhi Wang, Chang-Tang Chang, "Preparation and Characterization of Graphene Oxide", Journal of Nanomaterials, vol. 2014, Article ID 276143, 6 pages, 2014”.

[0104] The specific surface area according to the BET method is between 20 and 1000 m2 / g, preferably between 25 and 300 m2 / g.

[0105] Mono or multilayer graphene can comprise 1 layer of sp2 carbon atom (monolayer graphene in English), 2 to 5 layers (few layer graphene in English), 5 to 10 layers (multilayer graphene), beyond 10 layers but having a thickness of less than 100 nm (graphite or graphene nanoplatelets in English).

[0106] The number of graphene layers can be determined using X-ray diffraction or atomic force microscopy. Raman spectroscopy is preferred for graphene materials with few layers. The thickness and dimensions of graphene can also be determined using optical, scanning electron, or transmission electron microscopy. Methods for measuring the average thickness and lateral dimensions of graphene are described in ISO / TS 21356-1:2021

[0107] The graphene material can also be exfoliated graphite, thus retaining its crystallinity.

[0108] The graphene material can also be functionalized. The functions are advantageously chosen from primary amines, carboxylic acids and anhydrides.

[0109] The graphene according to the invention is not a graphene oxide.

[0110] The graphene preferably has an average thickness of between 1 and 100 nm, preferably between 1.5 and 50 nm, more preferably between 2 and 25 nm.

[0111] The graphene according to the invention has lateral dimensions of between 0.4 and 50 pm, preferably between 2 and 40 pm.

[0112] Advantageously, the graphene, when it comprises a function, and the polyamide are covalently linked by an amide, ester, urea or urethane function, preferably amide. Impact modifier

[0113] The composition of the invention may further comprise an impact modifier.

[0114] The impact modifier may be present up to 40% by weight relative to the total weight of the composition. Thus, the impact modifier content in the composition of the invention is between 0 and 40% by weight relative to the total weight of the composition.

[0115] In one embodiment, the impact modifier is present up to 35% by weight relative to the total weight of the composition, in particular up to 30% by weight relative to the total weight of the composition, preferably up to 15% by weight, preferably up to 12% by weight relative to the total weight of the composition.

[0116] In another embodiment, the impact modifier is present from 3 to 40% by weight relative to the total weight of the composition, in particular from 3 to 35% by weight, in particular from 3 to 30% by weight, preferably from 3 to 15% by weight, for example from 3 at 12% by weight, relative to the total weight of the composition.

[0117] The impact modifier is advantageously constituted by a polymer having a flexural modulus of less than 100 MPa measured according to the ISO 178: 2010 standard, determined at 23°C with a relative humidity: RH50%, and a Tg of less than 0°C (measured according to the 11357-2: 2013 standard at the inflection point of the DSC thermogram, at a heating rate of 20K / min), in particular a polyolefin, the polyolefin may be coupled, or not, with a PEBA having a flexural modulus of less than 200 Mpa, the impact modifier may also be a polyether block amide (PEBA).

[0118] The polyolefin 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.

[0119] A non-functionalized polyolefin (B2) is typically 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:

[0120] - homopolymers and copolymers of polyethylene, in particular LD PE, HDPE, LLDPE (linear low density polyethylene), VLDPE (very low density polyethylene) and metallocene polyethylene.

[0121] - homopolymers or copolymers of propylene.

[0122] - ethylene / alpha-olefin copolymers such as ethylene / propylene, EPR (short for ethylene-propylene-rubber) and ethylene / propylene / diene rubber (EPDM).

[0123] - styrene / ethylene-butene / styrene (SEBS) block copolymers, styrene / butadiene / styrene (SBS), styrene / isoprene / styrene (SIS), styrene / ethylene-propylene / styrene (SEPS).

[0124] - 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.

[0125] 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 anhydrides of carboxylic acids such as maleic anhydride. A functionalized polyolefin is for example a PE / EPR blend, the weight ratio of which can vary widely, for example between 40 / 60 and 90 / 10, said blend being co-grafted with an anhydride, in particular maleic anhydride, according to a grafting rate for example of 0.01 to 5% by weight.

[0126] 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:

[0127] - PE, PP, copolymers of ethylene with propylene, butene, hexene, or octene containing for example from 35 to 80% by weight of ethylene;

[0128] - ethylene / alpha-olefin copolymers such as ethylene / propylene, EPRs (short for ethylene-propylene-rubber) and ethylene / propylene / diene (EPDM).

[0129] - styrene / ethylene-butene / styrene (SEBS) block copolymers, styrene / butadiene / styrene (SBS), styrene / isoprene / styrene (SIS), styrene / ethylene-propylene / styrene (SEPS).

[0130] - ethylene and vinyl acetate (EVA) copolymers, containing up to 40% in vinyl acetate weight;

[0131] - ethylene and alkyl (meth)acrylate copolymers, containing up to 40% in weight of alkyl (meth)acrylate;

[0132] - ethylene and vinyl acetate (EVA) and alkyl (meth)acrylate copolymers, containing up to 40% by weight of comonomers.

[0133] 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).

[0134] The functionalized polyolefin (Bl) may also be a co- or ter-polymer of at least the following units: (1) ethylene, (2) alkyl (meth)acrylate or saturated carboxylic acid vinyl ester and (3) anhydride such as maleic anhydride or (meth)acrylic acid or epoxy such as glycidyl (meth)acrylate.

[0135] 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 10% by weight of the copolymer:

[0136] - ethylene / alkyl (meth)acrylate / (meth)acrylic acid copolymers or maleic anhydride or glycidyl methacrylate;

[0137] - ethylene / vinyl acetate / maleic anhydride or methacrylate copolymers glycidyl;

[0138] - ethylene / vinyl acetate or alkyl (meth)acrylate / acid copolymers (meth)acrylic or maleic anhydride or glycidyl methacrylate.

[0139] In the preceding copolymers, the (meth)acrylic acid can be salified with Zn or Li.

[0140] 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.

[0141] Furthermore, the abovementioned 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 abovementioned 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.

[0142] The above-mentioned copolymers, (B1) and (B2), can be copolymerized in a random or block manner and have a linear or branched structure.

[0143] The molecular weight, MFI index, and density of these polyolefins can also vary to a large extent, which will be appreciated by those skilled in the art. MFI, short for Melt Flow Index, is the melt flow index. It is measured according to ASTM 1238.

[0144] 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 olefinic 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.

[0145] Advantageously, the functionalized polyolefins (B1) are chosen from all polymers 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® (SK Functional polymer) or polyolefins grafted with maleic anhydride such as Orevac® (SK Functional polymer) 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 oligomers may also be mentioned. polyamide monoamines.

[0146] Preferably, the impact modifier of the invention, which is preferably a polyolefin as described above, has an atomic carbon content of less than 90%, preferably less than 80%, more preferably less than 70%, relative to the number of atoms of the polyolefin except the hydrogen atoms. This carbon content makes it possible to determine a certain polarity of the impact modifier. The carbon content of the impact modifier can be measured by any technique known to those skilled in the art and in particular by elemental analysis.

[0147] Preferably, the impact modifier is chosen from polyolefins comprising polar monomers such as vinyl acetates, acrylic or methacrylic acids, acrylates, methacrylates and glycidyl methacrylate or a PEBA, preferably the impact modifier is a PEBA.

[0148] In a particular embodiment, the composition according to the invention does not comprise an impact modifier of functionalized or non-functionalized polyolefin type or comprises less than 5% by weight, preferably less than 3% by weight, preferably less than 1% by weight, preferably less than 0.5% by weight, of impact modifier of functionalized or non-functionalized polyolefin type, relative to the total weight of the composition. In a particularly preferred embodiment, the composition according to the invention does not comprise an impact modifier of functionalized or non-functionalized polyolefin type.

[0149] In one embodiment the composition does not comprise an impact modifier or less than 5% by weight of impact modifier, preferably less than 3% by weight, preferably less than 1% by weight, preferably less than 0.5% by weight, relative to the total weight of the composition. In one embodiment, the composition does not comprise an impact modifier. Additive

[0150] The composition according to the invention may further comprise at least one additive. The additive may be present up to 5% by weight relative to the total weight of the composition. Thus, the composition according to the invention comprises from 0 to 5% by weight of additive relative to the total weight of the composition.

[0151] In one embodiment, the additive is present from 0.1 to 5% by weight relative to the total weight of the composition of the layer (I).

[0152] The additives may be selected from an antioxidant, a polycondensation catalyst, a heat stabilizer, a UV absorber, a light stabilizer, a lubricant, an inorganic filler, a flame retardant, a nucleating agent, a plasticizer, a colorant, carbon black and carbon nanofillers.

[0153] In the context of the present invention, the term “polycondensation catalyst” means the catalysts used for the preparation of the polyamide.

[0154] Preferably, the composition of the invention comprises as additive at least one organic or inorganic stabilizer such as phenolic, phosphite or copper-containing antioxidants.

[0155] In one embodiment, the composition of the invention may further comprise from 5 to 49% by weight, preferably from 5 to 30% by weight, relative to the total weight of the composition, of short reinforcing fibers.

[0156] the so-called short fibers have a length of between 100 and 400 pm, preferably between 200 and 400 pm.

[0157] These short reinforcing fibers can be chosen from: - natural fibers - mineral fibers, these having high melting temperatures Tf and higher than the melting temperature Tf of said semi-crystalline polyamide of the invention and higher than the polymerization and / or processing temperature. - polymeric or polymer fibers having a melting temperature Tf' or, failing Tf', a glass transition temperature Tg', higher than the polymerization temperature or higher than the melting temperature Tf of said semi-crystalline polyamide constituting said matrix of the thermoplastic material and higher than the processing temperature. - or mixtures of the fibers mentioned above.

[0158] As mineral fibers suitable for the invention, mention may be made of carbon fibers, which includes nanotube fibers or carbon nanotubes (CNTs), carbon nanofibers or graphenes; silica fibers such as glass fibers, in particular of type E, R or S2; boron fibers; ceramic fibers, in particular silicon carbide fibers, boron carbide fibers, boron carbonitride fibers, silicon nitride fibers, boron nitride fibers, basalt fibers; fibers or filaments based on metals and / or their alloys; fibers of metal oxides, in particular alumina (A12O3); metallized fibers such as metallized glass fibers and metallized carbon fibers or mixtures of the aforementioned fibers.

[0159] More particularly, these fibers can be chosen as follows: - the mineral fibers may be chosen from: carbon fibers, carbon nanotube fibers, glass fibers, in particular of type E, R or S2, boron fibers, ceramic fibers, in particular silicon carbide fibers, boron carbide fibers, boron carbonitride fibers, silicon nitride fibers, boron nitride fibers, basalt fibers, fibers or filaments based on metals and / or their alloys, fibers based on metal oxides such as Al2O3, metallized fibers such as glass fibers metallized and metallized carbon fibers or mixtures of the aforementioned fibers, and - the polymer or polymeric fibers, under the condition mentioned above, are chosen from: - thermosetting polymer fibers and more particularly chosen from: unsaturated polyesters, epoxy resins, vinyl esters, phenolic resins, polyurethanes, cyanoacrylates and polyimides, such as bis-maleimide resins, aminoplasts resulting from the reaction of an amine such as melamine with an aldehyde such as glyoxal or formaldehyde, - thermoplastic polymer fibers and more particularly chosen from: - polyamide fibers, in particular polyphthalamide fibers, - aramid fibers (such as Kevlar®) and aromatic polyamides such as those corresponding to one of the formulas: PPD.T, MPD.I, PAA and PPA, with PPD and MPD being respectively p- and m-phenylenediamine, PAA being polyarylamides and PPA being polyphthalamides, - polyamide block copolymer fibers such as polyamide / polyether, polyarylether ketone (PAEK) fibers such as polyetherether ketone (PEEK), polyetherketone ketone (PEKK), polyetherketone-etherketone ketone (PEKEKK).

[0160] The preferred short reinforcing fibers are short fibers chosen from: carbon fibers, including metallized, glass fibers, including metallized type E, R, S2, aramid fibers (such as Kevlar®) or aromatic polyamides, polyarylether ketone fibers (PAEK), such as polyetherether ketone (PEEK), polyetherketone ketone fibers (PEKK), polyetherketoneetherketone ketone fibers (PEKEKK) or mixtures thereof.

[0161] The natural fibers may be chosen from flax, castor, wood, sisal, kenaf, coconut, hemp and jute fibers.

[0162] Preferably, the reinforcing fibers present in the composition according to the invention are chosen from glass fibers, carbon fibers, flax fibers and their mixtures, and more preferably glass fibers and carbon fibers, and even more preferably glass fibers.

[0163] Preferably, the composition of the invention does not comprise continuous fibers.

[0164] In a preferred embodiment, the composition of the invention does not comprise long reinforcing fibers, i.e. reinforcing fibers of length greater than 400 μm. Plasticizer

[0165] The composition according to the invention may further comprise at least one plasticizer. The plasticizer content in the composition according to the invention is from 0 to 14% by weight relative to the total weight of the composition.

[0166] The plasticizers are, for example, chosen from benzene sulfonamide derivatives, such as n-butyl benzene sulfonamide (BBSA); ethyl toluene sulfonamide or N-cyclohexyl toluene sulfonamide; hydroxybenzoic acid esters, such as ethyl-2-hexyl parahydroxybenzoate and decyl-2-hexyl parahydroxybenzoate; esters or ethers of tetrahydrofurfuryl alcohol, such as oligoethyleneoxytetrahydrofurfuryl alcohol; and esters of citric acid or hydroxymalonic acid, such as oligoethyleneoxy malonate.

[0167] It would not be outside the scope of the invention to use a mixture of plasticizers.

[0168] In one embodiment, the plasticizer is present in the composition from 1 to 14% by weight, in particular from 1 to 12% by weight relative to the total weight of the composition.

[0169] In another embodiment, the plasticizer is present from 5 to 14%, in particular from 5 to 12% by weight relative to the total weight of the composition.

[0170] In a preferred embodiment, the composition of the invention does not comprise a plasticizer. Method of preparing the composition

[0171] The present invention also relates to a process for preparing a composition as described above.

[0172] In a first embodiment, the process for preparing the composition according to the invention comprises the steps of: i. Preparation of a masterbatch by dispersing graphene in a polyamide matrix; then ii. Mixing the masterbatch in the polyamide according to the invention comprising the possible impact modifiers, additives and plasticizers.

[0173] Preferably, in step (i) the graphene content is 10 to 50% by weight relative to the weight of the masterbatch.

[0174] Advantageously, the polyamide of the masterbatch is identical to the polyamide of the composition according to the invention.

[0175] Preferably in step (ii) the masterbatch content is between 1 and 20% relative to the total weight of the mixture obtained in step (ii).

[0176] Preferably, in step (ii), the masterbatch and the polyamide are mixed in the molten state. The mixing may take place in any device for mixing, kneading or extruding plastics in the molten state known to those skilled in the art, such as an internal mixer, a cylinder mixer, an extruder, such as a single-screw extruder or a contra- or co-rotating twin-screw extruder, a co-kneader, such as than a continuous co-kneader, or a stirred reactor. Preferably, the mixing takes place in an extruder or co-kneader, more preferably in an extruder, even more preferably in a twin-screw extruder.

[0177] Preferably, the mixing in step (ii) is carried out at a temperature at least 10°C higher than the melting point of the polyamide, preferably at a temperature at least 20°C higher than the melting point of the polyamide, preferably at a temperature at least 30°C higher than the melting point of the polyamide.

[0178] Advantageously, the mixing is carried out for a period of 30 seconds to 15 minutes, preferably 40 seconds to 10 minutes. Preferably, the mixing is carried out with stirring.

[0179] Before their mixing in step (ii), the masterbatch and the polyamide can independently be in the form of powder or granules.

[0180] Advantageously, the preparation process comprises a step of shaping the mixture obtained in step (ii) into granules or powder form. When the mixture is put into powder form, it is preferably first put into granules or flakes and then the granules or flakes are ground into powder. Any type of mill can be used, such as a hammer mill, a pin mill, an attrition disc mill or an impact classifier mill.

[0181] In another embodiment, the composition according to the invention can be prepared, preferably in one step, by dispersing the graphene in the polyamide according to the invention in the molten state, optionally in the presence of additives, impact modifier and / or plasticizer.

[0182] In this embodiment, the preparation method comprises a step of shaping the mixture obtained into granules or powder. When the mixture is formed into powder, it is preferably first formed into granules or flakes and then the granules or flakes are ground into powder. Any type of mill may be used, such as a hammer mill, a pin mill, an attrition disc mill or an impact classifier mill.

[0183] This second embodiment concerning the method is not preferred given that it poses health risks (inhalation in particular) due to the small size of the graphene particles.

[0184] Preferably, the composition according to the invention is not obtained by polymerization of the polyamide in the presence of graphene. Indeed, such a process requires significant quantities of solvent and is therefore not preferred for environmental and economic reasons. In addition, the use of graphene in the polymerization reactor pollutes said reactor. Single-layer or multi-layer structure

[0185] The present invention also relates to single-layer or multi-layer structures wherein the layer in the case of the single-layer structure or at least one of the layers in the case of the multi-layer structure is formed in whole or in part from the composition according to the invention, preferably consists of the composition according to the invention.

[0186] The structures according to the present invention are preferably intended for the transport, storage and / or distribution of fluid, in particular fluid for transport vehicles, in particular motor vehicles and other transport vehicles such as trains, trucks, metros, etc.

[0187] The expression “motor vehicle” means any vehicle with a thermal, electric or

[0188] hybrid equipped with wheels or tracks excluding a flying vehicle.

[0189] The motor vehicle may be two-wheeled, three-wheeled, four-wheeled or tracked.

[0190] It is for example chosen from an electric bicycle, a moped, a motorcycle, a sidecar, a car, a van, a tractor, a truck, a bus, a coach, a snowmobile, a half-track, a bulldozer, a snow groomer and a tank. In particular, it is chosen from a car, a van, a truck, a bus and a coach.

[0191] The single-layer or multi-layer structures of the present invention may be tanks, pipe (or tube), liner. Throughout the description, the term "tube" or "pipe" may be used and designates the same thing.

[0192] In one embodiment, the present invention relates to single-layer or multi-layer reservoir-type structures for fluid storage, comprising at least one layer obtained with the composition of the invention, preferably comprising at least one layer made of the composition of the invention.

[0193] In another embodiment, the present invention relates to single-layer or multi-layer tubular (MLT) structures intended for the transport and distribution of fluid, comprising at least one layer obtained with the composition of the invention, preferably comprising at least one layer made of the composition according to the invention.

[0194] Preferably, the multilayer structures comprise at least one further layer, preferably comprising a polyamide.

[0195] The multilayer structures according to the present invention (MLT or reservoir) comprise at least one layer obtained with the composition of the invention, preferably a layer consisting of the composition according to the invention, preferably this layer is the innermost layer (in contact with the fluid), and one or more other layers for example chosen from the group consisting of the reinforcing layers (in particular composite layer), the sealing layers (barrier layer), the chemical resistance layers, burst resistance layers, etc. These multilayer structures are well known to those skilled in the art.

[0196] The term "fluid" designates a gas, in particular used in automobiles, or a liquid, in particular used in the automotive field. Examples of liquids are in particular an oil, a brake fluid, a urea solution, a glycol-based coolant, fuels, in particular fuels, in particular gasoline, diesel, LPG, bio-gasoline or bio-diesel, in particular gasoline and more particularly alcoholic gasoline. The fluid according to the invention may also be hydrogen.

[0197] In a preferred embodiment, air, nitrogen and oxygen are excluded from the definition of said fluid.

[0198] In one embodiment, said fluid designates fuels, in particular gasoline, in particular alcoholic gasoline.

[0199] In another embodiment, said fluid designates hydrogen.

[0200] The term "gasoline" designates a mixture of hydrocarbons resulting from the distillation of petroleum to which additives or alcohols such as methanol and ethanol may be added, the alcohols being able to be the majority components in certain cases.

[0201] The term "alcohol-based gasoline" refers to gasoline to which methanol or ethanol has been added. It also refers to E95-type gasoline that does not contain petroleum distillation products.

[0202] In the present invention, the tank may be a tank for mobile storage of hydrogen, i.e. on a truck for transporting hydrogen, on a car for transporting hydrogen and supplying hydrogen to a fuel cell for example, on a train for supplying hydrogen or on a drone for supplying hydrogen, but it may also be a stationary hydrogen storage tank at a station for distributing hydrogen to vehicles. The tank may also be a tank for storing fuel or coolant.

[0203] In one embodiment, the multilayer structure according to the present invention may for example be a hydrogen tank and comprises or consists of several layers, in particular two layers, excluding a film or a granule. Generally, hydrogen tanks comprise at least one barrier layer (or sealing layer) and a reinforcing layer. The hydrogen tanks may comprise or consist of, for example, several sealing layers and several reinforcing layers, or a sealing layer and several reinforcing layers, or several sealing layers and a reinforcing layer or a sealing layer and a reinforcing layer.

[0204] The expression “barrier layer” (or “sealing layer”) designates a layer having characteristics of low permeability and good resistance to the various constituents of fluids, in particular fuels and hydrogen. That is to say that the barrier layer slows down the passage of the fluid, in particular fuel (both for its polar components (such as ethanol) and for its apolar components (hydrocarbons)) or hydrogen, into the other layers of the structure or even outside the structure. The barrier layer is therefore a layer which above all prevents too much gasoline from being lost into the atmosphere by diffusion, thus preventing atmospheric pollution.

[0205] Thus, the present invention preferably relates to: - a single-layer or multi-layer tubular structure, for the transport, distribution or storage of fluid, comprising at least one layer, preferably an internal layer, formed in whole or in part from the composition according to the invention, preferably comprising at least one layer, preferably an internal layer, made of the composition according to the invention; - a single-layer tubular structure, for the transport, distribution or storage of fluid, formed in whole or in part from the composition according to the invention, preferably the single-layer tubular structure is made of the composition according to the invention; - a multi-layer tubular structure, for the transport, distribution or storage of fluid, comprising at least one layer, preferably an internal layer, formed in whole or in part from the composition according to the invention, preferably comprising at least one layer, preferably an internal layer, consisting of the composition according to the invention and at least one other layer, preferably the other layer comprises a polyamide; - a single-layer or multi-layer tank for transporting or storing fluid, comprising at least one layer, preferably an internal layer, formed in whole or in part from the composition according to the invention, preferably comprising at least one layer, preferably an internal layer, made of the composition according to the invention; - a single-layer tank, for the transport or storage of fluid, formed in whole or in part from the composition according to the invention, preferably the single-layer tank is made of the composition according to the invention; - a multi-layer tank, for transporting or storing fluid, comprising at least one layer, preferably an internal layer, formed in whole or in part from the composition according to the invention, preferably comprising at least one layer, preferably an internal layer, consisting of the composition according to the invention and at least one other layer, preferably the other layer comprises a polyamide.

[0206] In one embodiment, the structures of the present invention can be used for the transportation, distribution and storage of hydrogen (H2).

[0207] In another embodiment, the structures of the present invention may be used for the transportation, distribution and storage of coolant.

[0208] In another embodiment, the structures of the present invention can be used for the transportation, distribution and storage of fuel.

[0209] The present invention also relates to a process for preparing single-layer or multi-layer structures as described above, comprising a step of manufacturing a sealing layer by injection, extrusion, extrusion-blow molding or rotational molding using the composition according to the invention.

[0210] In one embodiment, the structure is a multi-layer structure and further comprises a step of filament winding the reinforcing layer as defined above around the sealing layer as defined above. Use of the composition

[0211] The present invention also relates to the use of the composition according to the invention for the manufacture of a single-layer or multi-layer structure, as described above. The single-layer or multi-layer structure is preferably obtained by a step of preparing at least one layer comprising the composition according to the invention by injection, extrusion, extrusion-blow molding or rotational molding using the composition of the invention. Other layers may also be present and in particular implemented simultaneously. Use of graphene

[0212] The present invention also relates to the use of 0.05 to 20% by weight, preferably 0.1 to 15% by weight, more preferably 0.1 to 5% by weight, even more preferably 0.1 to 2% by weight, of at least one graphene, other than graphene oxide, in a composition comprising at least 50% by weight of at least one polyamide having a C / N atomic ratio greater than 6.5, preferably greater than 8, more preferably greater than 9, optionally up to 5% by weight of at least one additive, optionally up to 40% by weight of at least one impact modifier and / or optionally up to 14% by weight of at least one plasticizer, the percentages being given relative to the total weight of the composition, to obtain an extractable content less than or equal to 4g / m2, preferably less than or equal to 3g / m2.

[0213] The present invention also relates to the use of 0.05 to 20% by weight, preferably 0.1 to 15% by weight, more preferably 0.1 to 5% by weight, even more preferably 0.1 to 2% by weight, of at least one graphene, other than graphene oxide, in a composition comprising at least 50% by weight of at least one polyamide having a C / N atomic ratio greater than 6.5, preferably greater than 8, more preferably greater than 9, optionally up to 5% by weight of at least one additive, optionally up to 40% by weight of at least one impact modifier and / or optionally up to 14% by weight of at least one plasticizer, the percentages being given relative to the total weight of the composition, to obtain an extractable rate lower than that obtained for the same composition free of graphene. In the context of the present invention, the term "same composition free of graphene" means a comparative composition in which the graphene has been replaced by the same quantity of polyamide, all other things being equal.It should be understood that when the composition according to the invention comprises a mixture of polyamide then the polyamide which replaces the graphene in the comparative composition is the same mixture of polyamide as that of the composition according to the invention in the same relative proportions.

[0214] In one embodiment, the extractable content is determined by a test consisting of filling a tubular structure with FAM-B type alcoholic essence and heating the assembly to 60°C for 96 hours, then emptying the tube by filtering it into a beaker. The beaker filtrate is then allowed to evaporate at room temperature and the residue is weighed, thus giving the extractable content per unit of internal tube surface area. This measurement method is described in particular in standard TL52712.

[0215] Alcoholic gasoline FAM B is described in DIN 51604-1:1982, DIN 51604-2:1984 and DIN 51604-3:1984. Briefly, alcoholic gasoline FAM A is first prepared with a mixture of 50% toluene, 30% isooctane, 15% di-isobutylene and 5% ethanol and then FAM B is prepared by mixing 84.5% FAM A with 15% methanol and 0.5% water. In total, FAM B consists of 42.3% toluene, 25.4% isooctane, 12.7% di-isobutylene, 4.2% ethanol, 15% methanol and 0.5% water.

[0216] The term extractable is understood to mean all the compounds originating from the composition forming the layers of the monolayer or multilayer structure and which can be entrained by the fluid; examples of extractables are plasticizers, monomers, oligomers, additives, etc.

[0217] The present invention also relates to the use of 0.05 to 20% by weight, preferably 0.1 to 15% by weight, more preferably 0.1 to 5% by weight, even more preferably 0.1 to 2% by weight, of at least one graphene, other than graphene oxide, in a composition comprising at least 50% by weight of at least one polyamide having a C / N atomic ratio greater than 6.5, preferably greater than 8, more preferably greater than 9, optionally up to 5% by weight of at least one additive, optionally up to 40% by weight of at least one impact modifier and / or optionally up to 14% by weight of at least one plasticizer, the percentages being given relative to the total weight of the composition, to obtain a permeability lower than that obtained for the same composition free of graphene. In the context of the present invention, the same composition free of graphene is understood to mean a comparative composition in which the graphene has been replaced by the same quantity of polyamide, all other things being equal. It should be understood that when the composition according to the invention comprises a mixture of polyamide then the polyamide which replaces the graphene in the comparative composition is the same mixture of polyamide as that of the composition according to the invention in the same relative proportions.

[0218] The permeability according to the invention is the permeability of the single-layer or multi-layer structure to the fluid.

[0219] In a particular embodiment, the measured permeability is the hydrogen permeability and is measured according to ISO 15105-2 at atmospheric pressure.

[0220] The definitions and contents of polyamide, graphene, impact modifier, plasticizer and additive mentioned above also apply.

[0221] The single-layer or multi-layer structures of the invention therefore have good permeability, in particular permeability to hydrogen and a low extractable rate. Recyclable

[0222] Particularly advantageously, the structures obtained with the composition of the invention are recyclable.

[0223] The term "recyclable" means that said single or multi-layer structure after use and therefore after transport, distribution or storage of fluids, can be reused, in particular after grinding, that is to say implemented in a method for manufacturing a part, in particular a new single or multi-layer structure, in particular by extrusion while obtaining good mechanical properties, in particular cold impact, a high bursting stress, a high elongation at break, unlike the recycling of a structure not comprising graphene. In the context of the present invention, the term "same composition free of graphene" means a comparative composition in which the graphene has been replaced by the same quantity of the polyamide, all other things being equal.It should be understood that when the composition according to the invention comprises a mixture of polyamide then the polyamide which replaces the graphene in the comparative composition is the same mixture of polyamide as that of the composition according to the invention in the same relative proportions.

[0224] The grinding is carried out according to the conventional techniques of those skilled in the art to a size of 1 mm to 2 cm.

[0225] Said reuse of said used tubular structure can be carried out in a mixture or not with virgin material.

[0226] The invention will be explained in more detail in the following examples. Examples

[0227] Unless otherwise stated, the percentages are expressed by weight relative to the total weight of the composition.

[0228] The compositions described in Table 2 were prepared by compounding under the following conditions: The compositions 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. All the materials were added to the main hopper at the start of the screw.

[0229] 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.

[0230] Graphene is a graphene consisting of 99 mol% carbon atoms and having a BET surface area of ​​250 m2 / g. Graphene is not a graphene oxide.

[0231] The graphene used, from the company Graphene Production, has the following characteristics:

[0232] [Tables 1] Purity >99% Average thickness 1-2 nm Average lateral dimension (X&Y) 0.5-5 pm Number of layers 2-5 Bulk density 0.2-0.4 g / cm3 Specific surface area Approx. 250 m2 / g

[0233] Graphene was added as a master batch comprising 10% by weight of graphene and 90% of PA 11.

[0234] The organic stabilizer used is a mixture consisting of 80% Irganox® 1010 and 20% Irgafos® 168 from BASF.

[0235] [Tables2] Comparative Example 1 Inventive Example 1 Inventive Example 2 PA 11 (wt%) 99 98.5 97 Graphene (wt%) 0.5 2 Organic Stabilization (wt%) 1 1 1 Total 100 100 100

[0236] Liners with a thickness of 3 mm of the comparative and inventive compositions were prepared by blow-molding and the hydrogen permeability at 15°C was tested on plates of dimension 100*100*3 mm cut from the prepared liners.

[0237] This test 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. The measurement is carried out according to the ISO 15105-2 standard.

[0238] The experimental conditions are presented in the following Table 3.

[0239] [Tables3] Device Coupling LYSSY GPM500 / GC Chromatographic detection (TCD) Column Poraplot Q (L=27.5m, Dint=0.530mm, Ep.film=20q) 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 Isothermal oven 30°C Temperature Detector 200°C detector: TCD [-] Injector temperature Temperature of the lyssy injection loop Temperature / Relative humidity 15°C / 0%RH

[0240] Single-layer tubes of dimension 8*1mm were also extruded to evaluate the rate of soluble extractable after aging in FAM B gasoline according to VW standard TL52712. This test consists of filling the tube with FAM-B type alcoholic gasoline at 60°C for 96 hours. The tube is then emptied into a beaker and its contents are then evaporated and the residue obtained is weighed. The quantity of residue must be as small as possible.

[0241] The results are given in Table 4

[0242] [Tables4] Comparative Example 1 Inventive Example 1 Inventive Example 2 Permeability (NcmA3 / h, 3mm, 15°C, 1 am) 1.2 0.9 0.8 Soluble extractable content after aging in FAM B at 60°C 5.9 4 1.7

[0243] The compositions of the invention make it possible to obtain structures having low permeabilities to hydrogen and make it possible to improve the durability of thermal engines by significantly reducing the level of extractables in the gasoline lines.

Claims

Claims

1. Composition comprising, relative to the total weight of the composition: - At least 50% by weight of at least one polyamide having a C / N atomic ratio greater than 6.5; - From 0.05 to 20% of at least one graphene, the graphene being different from graphene oxide.

2. Composition according to claim 1, further comprising: - up to 40% by weight, relative to the weight of the composition of at least one impact modifier; and / or - Up to 5% by weight of at least one additive; and / or - Up to 14% by weight of at least one plasticizer; and / or - From 5 to 49% by weight of short reinforcing fibers.

3. Composition according to any one of the preceding claims in which the polyamide is: - An aliphatic polyamide resulting from the polycondensation of: • at least one C6 to C18 amino acid, preferably C10 to C18, even more preferably C10 to C12; or • at least one C6 to C18 lactam, preferably C10 to C18, even more preferably C10 to C12; or • at least one C4-C36 aliphatic diamine Xa, preferably C5-C18, preferably C5-C12, more preferably C10-C12 with at least one C4-C36 aliphatic diacid Yb, preferably C6-C18, preferably C6-C12, more preferably C10-C12;or - A semi-aromatic polyamide of formula XAr or Ar'Y in which XAr denotes a unit obtained from the polycondensation of a diamine X and an aromatic dicarboxylic acid Ar, the diamine X being C6-C36, preferably C6-C18, preferably C6-C12, more preferably C10-C12, Ar'Y denotes a unit obtained from the polycondensation of an aromatic diamine Ar' and a; aliphatic dicarboxylic acid Y, the aromatic diamine Ar' being for example chosen from MXD (metaxylylene diamine) and PXD (paraxylylene diamine).

4. Composition according to any one of the preceding claims in which the polyamide is: - An aliphatic polyamide chosen from PA610, PA612, PA1010, PA1012, PA1014, PA1212, PA1214, PAU, PA12, preferably PA610, PA1010, PA1012, PA1014, PA1212, PA1214, PAU; preferably PAU, PA 12, preferably PA11 - A semi-aromatic polyamide chosen from PA 10T / TMDT, PA 1,3BACT / 6T / 10T, PA 1,3BACT / 6T, PA 12 / BI / BT, PA 12 / BI, PA TMDT, PA 10T / BACT, PA MXD6 / MXDT, PA 9T, PA 10T, PA MXD10 / MXDT, PA PXD6 / PXDT, PA PXD10 / PXDT, PA MXDT / BACT, PA MXD10 / BACT.

5. Composition according to any one of the preceding claims in which the impact modifier is chosen from functionalized or non-functionalized polyolefins or PEBAs.

6. A single-layer or multi-layer structure wherein the layer in the case of the single-layer structure or at least one of the layers in the case of the multi-layer structure is formed in whole or in part from the composition as defined in any one of claims 1 to

7. J. Structure according to claim 6 characterized in that it is a tubular structure.

8. Structure according to claim 6 characterized in that it is a reservoir.

9. Use of the structure according to one of claims 6 to 9 for the transport, distribution and storage of a fluid.

10. Use according to claim 9, wherein the fluid is hydrogen.

11. Use according to claim 9, wherein the fluid is a coolant.

12. Use according to claim 9, wherein the fluid is a fuel.

13. Use of a composition according to any one of claims 1 to 5 for the manufacture of a single-layer or multi-layer structure by injection, extrusion, extrusion-blow molding or rotational molding, preferably by extrusion.

14. Use of 0.05 to 20% by weight of at least one graphene, said graphene not being a graphene oxide, in a composition comprising, relative to the total weight of the composition: - At least 50% by weight of at least one polyamide having a C / N atomic ratio greater than 6.5; the percentages being given relative to the total weight of the composition, to obtain an extractable rate of less than 4 g / m2, preferably less than 3 g / m2 according to standard TL52712.

15. Use of 0.05 to 20% by weight of at least one graphene, said graphene not being a graphene oxide, in a composition comprising, relative to the total weight of the composition: - At least 50% by weight of at least one polyamide having a C / N atomic ratio greater than 6.5; the percentages being given relative to the total weight of the composition, to obtain an extractable rate lower than that obtained for the same composition free of graphene, in which the graphene has been replaced by the same quantity of the polyamide of the composition.

16. Use of 0.05 to 20% by weight of at least one graphene, said graphene not being a graphene oxide, in a composition comprising, relative to the total weight of the composition: - At least 50% by weight of at least one polyamide having a C / N atomic ratio greater than 6.5; the percentages being given relative to the total weight of the composition, to obtain a fluid permeability lower than that obtained for the same composition without graphene, in which graphene was replaced by the same amount of polyamide in the composition.

17. Method of manufacturing a single-layer or multi-layer structure as defined according to one of claims 6 to 8, characterized in that it comprises a step of manufacturing a sealing layer by injection, extrusion, extrusion-blow molding or rotational molding.