Polyamide composition and polar graphene

Abstract

The invention relates to a composition comprising, with respect to the total weight of the composition: - at least 50 wt.% of at least one polyamide having an inherent viscosity of greater than 1.2; - from 0.05 to 20 wt.% of a polar graphene having an average thickness of between 0.5 and 75 nm; and - from 3 to 40 wt.% of at least one impact modifier. The invention also relates to the use of this composition for preparing single-layer or multi-layer structures for storing, transporting and dispensing fluid, in particular transport vehicle fluid.

Description

[0001] Composition of polyamide and polar graphene

[0002] Field of invention

[0003] The present invention relates to polyamide and graphene compositions for the manufacture of single-layer or multi-layer structures, in particular for fluid transport, distribution or storage applications.

[0004] Technical background

[0005] The fluid supply of transport vehicles, for example motor vehicles, trains, trucks, etc., including fuel supply for thermal vehicles, coolant supply, hydrogen supply for fuel cells, etc., requires the presence of storage, distribution and transport structures such as tanks, pipes, etc.

[0006] These structures must fulfill two essential functions:

[0007] Waterproofing or low permeability to limit fluid losses;

[0008] Mechanical resistance (tensile and shock).

[0009] 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.

[0010] 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, which, in addition to good mechanical strength properties, have:

[0011] Low permeability to limit fluid losses; and / or Low extractable rate.

[0012] There is also a need to provide such compositions for preparing fluid storage, distribution and / or transport structures further comprising:

[0013] Good fire resistance, in particular the structure is fire resistant with a VO, V1 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.

[0014] Summary of the invention

[0015] The invention relates firstly to a composition comprising, relative to the total weight of the composition:

[0016] - At least 50% by weight of at least one polyamide having an inherent viscosity greater than 1.2;

[0017] From 0.05 to 20% by weight of a polar graphene;

[0018] From 3 to 40% by weight of at least one impact modifier.

[0019] Particularly preferably, the present invention relates to a composition comprising, relative to the total weight of the composition:

[0020] - At least 50% by weight of at least one polyamide having an inherent viscosity greater than 1.2;

[0021] From 0.05 to 20% by weight of a polar graphene having an average thickness between 0.5 and 75 nm;

[0022] From 3 to 40% by weight of at least one impact modifier.

[0023] In one embodiment, the polar graphene is a graphene oxide or a graphene functionalized with at least one function reacting with the polyamide, preferably a function chosen from maleic anhydrides, carboxylic acids, primary amines, isocyanates, preferably maleic anhydrides and amines.

[0024] In one embodiment, the polyamide of the composition according to the invention is:

[0025] An aliphatic polyamide resulting from the polycondensation: o of at least one amino acid in C6 to C18, preferably in C9 to C18, more preferably in C10 to C18, even more preferably in C10 to C12, in particular in C11; or o of at least one lactam in C6 to C18, preferably in C9 to C18, more preferably in C10 to C18, even more preferably in C10 to C12, in particular in C12; or o at least one aliphatic diamine Ca in C4-C36, in particular in C6-C36, preferably C6-C18, preferably C6-C12, more preferably C10-C12 with at least one aliphatic diacid Cb in C4-C36, in particular in C6-C36, preferably C6-C18, preferably C10-C18, more preferably C10-C12; or

[0026] A semi-aromatic polyamide of formula A / XT in which A is selected from a unit obtained from an amino acid, a unit obtained from a lactam and a unit corresponding to the formula (Ce diamine). (Cd diacid), with c representing the number of carbon atoms of the diamine and d representing the number of carbon atoms of the diacid, c and d each being between 4 and 36, advantageously between 9 and 18, the unit (Ce diamine) being selected from linear or branched aliphatic diamines, as defined above, cycloaliphatic diamines and alkylaromatic diamines and the unit (Cd diacid) being selected from linear or branched aliphatic diacids, cycloaliphatic diacids and aromatic diacids; X.T denotes a unit obtained from the polycondensation of a Cx diamine and terephthalic acid, with x representing the number of carbon atoms of the Cx diamine, x being between 5 and 36, advantageously between 9 and 18, T corresponds to terephthalic acid.

[0027] Preferably, the polyamide is:

[0028] An aliphatic polyamide selected from PA6, PA66, PA11, PA12, PA610, PA612, PA1010, PA1012 and PA1212;

[0029] A semi-aromatic polyamide selected from 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 11 / MXDT / 10T, 11 / 5T / 10T, T is terephthalic acid, MXD is m-xylylenediamine, MPMD is methylpentamethylenediamine and BAC is bis(aminomethyl)cyclohexane.

[0030] According to one embodiment, the composition preferably comprises, relative to the total weight of polyamide, more than 50% by weight, preferably more than 70% by weight, more preferably more than 85% by weight, of aliphatic polyamide. Preferably, the composition according to the invention comprises, by weight relative to the total weight of polyamide, 100% by weight of aliphatic polyamide.

[0031] In one embodiment, the impact modifier is chosen from olefin copolymers and in particular copolymers comprising ethylene or propylene units. 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.

[0032] In one embodiment, these structures are tubular structures.

[0033] In another embodiment, these structures are reservoirs.

[0034] The present invention also relates to the use of said structures for the transport, distribution and storage of a fluid.

[0035] In one embodiment, the fluid is hydrogen.

[0036] In another embodiment, the fluid is a fuel.

[0037] 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.

[0038] The present invention also relates to the use of 0.05 to 20% by weight of at least one polar graphene having an average thickness of between 0.5 and 75 nm in a composition comprising at least 50% by weight of at least one polyamide having an inherent viscosity greater than 1.2, 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 1% by weight of at least one plasticizer, the percentages being given relative to the total weight of the composition, to obtain an extractable rate of less than or equal to 4g / m 2 , preferably less than or equal to 3g / m 2 .

[0039] The present invention also relates to the use of from 0.05 to 20% by weight of at least one polar graphene having an average thickness of between 0.5 and 75 nm in a composition comprising at least 50% by weight of at least one polyamide having an inherent viscosity greater than 1.2, 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 1% 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 which the graphene has been replaced by the same quantity of the polyamide.The present invention also relates to the use of 0.05 to 20% by weight of at least one polar graphene having an average thickness of between 0.5 and 75 nm in a composition comprising at least 50% by weight of at least one polyamide having an inherent viscosity greater than 1.2, 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 1% 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 which the graphene has been replaced by the same quantity of the polyamide.

[0040] The present invention also relates to a method for manufacturing a single-layer or multi-layer structure, characterized in that it comprises a step of manufacturing a sealing layer by injection, extrusion, extrusion-blow molding or rotational molding.

[0041] Particularly advantageously, 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.

[0042] Particularly advantageously, the composition according to the invention makes it possible to obtain a hydrogen permeability measured according to standard ISO 15105-2 at atmospheric pressure and at 60°C, less than 10.00 x 10 -16 mol.m / m 2 .s.Pa, preferably less than 9.50 x 10 -16 mol.m / m 2 .spa.

[0043] In addition to this characteristic, the composition according to the invention preferably makes it possible to obtain at least one of the following properties:

[0044] An extractable rate, measured according to the TL52712 standard, less than or equal to 4g / m 2 , preferably less than 3g / m 2 ;

[0045] A thermal conductivity, measured according to ASTMD5930-17, greater than 0.5 W / mK, preferably greater than 0.6 W / mK;

[0046] A surface resistivity, measured according to standard IEC62631-3-2 (2015) less than 10 A 6 Qm, preferably less than 10 A 4 Qm;

[0047] A tensile modulus measured according to ISO527 after conditioning for 15 days at 23°C and 50% relative humidity of between 100 and 3000 MPa, preferably between 800 and 2000 MPa; An elongation at break measured according to ISO527 after conditioning for 15 days at 23°C and 50% relative humidity of greater than 10%, preferably greater than 20%, in particular greater than 100%;

[0048] Impact resilience at 23°C, measured according to ISO1791eA, greater than 5 kJ / m 2 , preferably greater than 8 kJ / m 2 .

[0049] Detailed description

[0050] The invention is now described in more detail and in a non-limiting manner in the following description.

[0051] Unless otherwise stated, all percentages are by mass.

[0052] 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.

[0053] The present invention relates to a composition comprising, relative to the total weight of the composition:

[0054] - At least 50% by weight of at least one polyamide having an inherent viscosity greater than 1.2;

[0055] From 0.05 to 20% by weight of a polar graphene;

[0056] From 3 to 40% by weight of at least one impact modifier.

[0057] Preferably, the present invention relates to a composition comprising, relative to the total weight of the composition:

[0058] - At least 50% by weight of at least one polyamide having an inherent viscosity greater than 1.2;

[0059] From 0.05 to 20% by weight of a polar graphene having an average thickness between 0.5 and 75 nm;

[0060] From 3 to 40% by weight of at least one impact modifier.

[0061] The present invention also relates to the use of 0.05 to 20% by weight of at least one polar graphene in a composition comprising, relative to the total weight of the composition, at least 50% by weight of at least one polyamide having an inherent viscosity greater than 1.2, 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; to obtain an extractable rate of less than or equal to 4 g / m 2 , preferably less than 3 g / m 2according to standard TL52712. Preferably, the present invention also relates to the use of 0.05 to 20% by weight of at least one polar graphene having an average thickness of between 0.5 and 75 nm, in a composition comprising, relative to the total weight of the composition at least 50% by weight of at least one polyamide having an inherent viscosity greater than 1.2, 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; to obtain an extractable rate of less than or equal to 4 g / m 2 , preferably less than 3 g / m 2 according to the TL52712 standard.

[0062] The present invention also relates to the use of 0.05 to 20% by weight of at least one polar graphene in a composition comprising, relative to the total weight of the composition, at least 50% by weight of at least one polyamide having an inherent viscosity greater than 1.2, 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; to obtain an extractable rate lower than that obtained for the same composition free of graphene, in the graphene has been replaced by the same quantity of the polyamide of the composition.

[0063] Preferably, the present invention relates to the use of 0.05 to 20% by weight of at least one polar graphene having an average thickness of between 0.5 and 75 nm, in a composition comprising, relative to the total weight of the composition at least 50% by weight of at least one polyamide having an inherent viscosity greater than 1.2, 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; to obtain an extractable rate lower than that obtained for the same composition free of graphene, in the graphene has been replaced by the same quantity of the polyamide of the composition.

[0064] The present invention also relates to the use of 0.05 to 20% by weight of at least one polar graphene in a composition comprising, relative to the total weight of the composition at least 50% by weight of at least one polyamide having an inherent viscosity greater than 1.2, 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, to obtain a fluid permeability 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.The present invention preferably relates to the use of 0.05 to 20% by weight of at least one polar graphene having an average thickness of between 0.5 and 75 nm, in a composition comprising, relative to the total weight of the composition at least 50% by weight of at least one polyamide having an inherent viscosity greater than 1.2, 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, to obtain a fluid permeability 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.

[0065] Composition

[0066] Polyamide

[0067] 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.

[0068] The nomenclature used to define polyamides is described in ISO 1874-1:2011 "Plastics - Polyamide (PA) materials for molding and extrusion - Part 1: Designation", particularly on page 3 (tables 1 and 2) and is well known to those skilled in the art.

[0069] The polyamide has an inherent viscosity greater than 1.2, preferably greater than 1.3, more preferably greater than 1.4, even more preferably greater than 1.6.

[0070] The measurement of inherent (or intrinsic) viscosity is carried out in m-cresol. The method is well known to those skilled in the art. ISO 307:2007 is followed, but the solvent (using m-cresol instead of sulfuric acid), the temperature (being 20°C), and the concentration (0.5% by mass) are changed.

[0071] The polyamide of the invention is advantageously a polyamide compatible with use in injection or extrusion, preferably in extrusion.

[0072] The polyamide may be a homopolyamide or a copolyamide or a mixture thereof.

[0073] Polyamide is a semi-crystalline polyamide, i.e. a material which is generally solid at room temperature, and which softens when the temperature increases, in particular after passing its glass transition temperature (Tg), and which can exhibit a clear melting when passing its so-called melting temperature (Tf), and which becomes solid again when the temperature decreases below its crystallization temperature.

[0074] Tg, Te (crystallization temperature) and Tf are determined by differential scanning calorimetry (DSC) according to 11357-2:2013 and 11357-3:2013 respectively.

[0075] 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 1,000 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:

[0076] Device: Waters Alliance 2695 instrument

[0077] Solvent: Hexafluoroisopropanol stabilized with 0.05M potassium trifluoroacetate Flow rate: 1 ml / minute

[0078] Column temperature: 40°C.

[0079] Two columns in series: 1000 Â PFG and 100 Â PFG (PPS)

[0080] Sample concentration: 1 g / L (dissolution at room temperature for 24 h) Filtration of samples using a syringe fitted with an ACRODISC PTFE filter, diameter 25 mm, porosity 0.2 pm

[0081] Injection volume: 10Opl

[0082] Refractometric detection at 40°C with UV detection at 228 nm

[0083] Calibration by PMMA standards from 1,900,000 to 402 g.mol-1. Calibration curve modeled by a fifth-degree polynomial.

[0084] In one embodiment, the polyamide is chosen from an aliphatic polyamide, a semi-aromatic polyamide and a mixture of the two, advantageously an aliphatic polyamide.

[0085] Said aliphatic polyamide may be derived from the polycondensation: of at least one amino acid in C6 to C18, preferably in C9 to C18, more preferably in C10 to C18, even more preferably in C10 to C12, in particular in C11; or of at least one lactam in C6 to C18, preferably in C9 to C18, more preferably in C10 to C18, even more preferably in C10 to C12, in particular in C12; or at least one aliphatic diamine Ca in C4-C36, in particular in C6-C36, preferably C6-C18, preferably C6-C12, more preferably C10-C12 with at least one aliphatic diacid Cb in C4-C36, in particular in C6-C36, preferably C6-C18, preferably C10-C18, more preferably C10-C12.

[0086] 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. When said at least one aliphatic semi-crystalline polyamide is obtained from the polycondensation of at least one amino acid, it can therefore comprise a single amino acid or several amino acids.

[0087] Advantageously, said aliphatic semi-crystalline 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.

[0088] C6 to C12 lactams include caprolactam, decanolactam, undecanolactam, and lauryllactam.

[0089] When said at least one aliphatic semi-crystalline polyamide is obtained from the polycondensation of at least one lactam, it can therefore comprise a single lactam or several lactams.

[0090] Advantageously, said at least one aliphatic semi-crystalline polyamide is obtained from the polycondensation of a single lactam and said lactam is chosen from lauryllactam and undecanolactam, advantageously lauryllactam.

[0091] The Ca diamine can be linear or branched. Advantageously, it is linear.

[0092] Said at least one C4-C36 diamine Ca may in particular be chosen from butanemethylenediamine, 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.

[0093] Advantageously, said at least one diamine Ca is C6-C36 and chosen from 1,6-hexamethylenediamine, 1,7-heptamethylenediamine, 1,8-octamethylenediamine, 1,9-nonamethylenediamine, 1,10-decamethylenediamine, 2,2,4-trimethylhexanediamine (TMD), 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.

[0094] Said at least one Cb dicarboxylic acid in C4 to C36 can be chosen from butanedioic acid, pentanedioic 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.

[0095] The diacid may be linear or branched. Advantageously, it is linear. Preferably, the polyamide according to the invention has a C / N ratio greater than 6.5, preferably greater than 8, advantageously greater than 9.

[0096] Advantageously, the aliphatic polyamide is chosen from PA6, PA66, PA11, PA12, PA610, PA612, PA1010, PA1012 and PA1212, preferably PA11, PA12, PA610, PA612, PA1010, PA1012 and PA1212, preferably PA11, PA610, PA1010, PA1012 and PA1212, preferably PA11 and PA12, preferably PA11.

[0097] Said semi-aromatic polyamide may be, in particular, a semi-aromatic polyamide of formula X / YAr, as described in EP1505099, in particular a semi-aromatic polyamide of formula A / XT in which A is chosen from a unit obtained from an amino acid as defined above, a unit obtained from a lactam as defined above and a unit corresponding to the formula (Ce diamine). (Cd diacid), with c representing the number of carbon atoms of the diamine and d representing the number of carbon atoms of the diacid, c and d each being between 4 and 36, advantageously between 9 and 18, the (Ce diamine) unit being chosen from aliphatic diamines, linear or branched, as defined above, cycloaliphatic diamines and alkylaromatic diamines and the (Cd diacid) unit being chosen from aliphatic diacids, linear or branched, as defined above, cycloaliphatic diacids and aromatic diacids;

[0098] XT denotes a unit obtained from the polycondensation of a Cx diamine and terephthalic acid, with x representing the number of carbon atoms of the Cx diamine, x being between 5 and 36, advantageously between 9 and 18, in particular a polyamide of formula A / 5T, A / 6T, A / 9T, A / 10T or A / 11T, A being as defined above, in particular a polyamide chosen from a PA MPMDT / 6T, a PA11 / 10T, a PA 5T / 10T, a PA 11 / BACT, a PA 11 / 6T / 10T, a PA MXDT / 10T, a PA MPMDT / 10T, a PA BACT / 10T, a PA BACT / 6T, PA BACT / 10T / 6T, a PA 11 / BACT / 6T, PA 11 / MPMDT / 6T, PA 11 / MPMDT / 10T, PA 11 / BACT / 10T, one PA 11 / MXDT / 10T, one 11 / 5T / 10T.

[0099] T stands for terephthalic acid, MXD stands for m-xylylenediamine, MPMD stands for methylpentamethylenediamine, and BAC stands for bis(aminomethyl)cyclohexane.

[0100] Said semi-aromatic polyamide may also be a polyamide of formula ZAr in which Z is a unit resulting from the polycondensation of at least one aliphatic diamine in Ca as defined above and Ar is an aromatic dicarboxylic acid, in particular terepthalic acid, isophthalic acid and naphthalenic acid.

[0101] In one embodiment, the polyamide is aliphatic and selected from PA6, PA66, PA11, PA12, PA610, PA612, PA1010, PA1012 and PA1212.

[0102] In another embodiment, the polyamide is semi-aromatic and selected from polyamide 11 / 5T, 11 / 6T, 11 / 10T, MXDT / 10T, MPMDT / 10T and BACT / 10T. Preferably, the content of semi-aromatic polyamide is less than 30% by weight relative to the total weight of polyamide in the composition according to the invention.

[0103] In one embodiment, said polyamide of said composition is previously washed at least once with a system chosen from a polar solvent, in particular methanol, water or water vapor, or a mixture thereof.

[0104] According to a preferred embodiment, the composition comprises, relative to the total weight of polyamide, more than 50% by weight, preferably more than 70% by weight, more preferably more than 85% by weight, of aliphatic polyamide. Preferably, the composition according to the invention comprises, by weight relative to the total weight of polyamide, 100% by weight of aliphatic polyamide.

[0105] Polar graphene

[0106] 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, preferably from 0.1 to 1.75% by weight, more preferably from 0.1 to 1.5% by weight, more preferably from 0.1 to 1% by weight, and even more preferably between 0.1 and 0.75% by weight of at least one polar graphene.

[0107] 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 graphene 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.

[0108] The specific surface area is measured according to the BET method as described in ISO 9277:2010.

[0109] "Polar graphene" means graphene comprising more than just carbon atoms, i.e. graphene comprising carbon atoms and other atoms such as, for example, heteroatoms, for example, O, N, F, etc.

[0110] Preferably, the polar graphene comprises oxygen atoms. Preferably, the polar graphene according to the invention has a carbon atom content, relative to the total number of atoms of the graphene (with the exception of any hydrogen atoms present in the graphene) of less than or equal to 99.9%, preferably between 55 and 99.5%, advantageously between 65 and 98%, more preferably between 75 and 95%, even more preferably between 90 and 99.5%.

[0111] Preferably, the polar graphene according to the invention has a heteroatom content (for example O, N, F, etc.) of between 0.1 and 45%.

[0112] Preferably, the polar 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) of between 0.1 and 45%, preferably between 5 and 35%, preferably between 0.5 and 10%.

[0113] Preferably, the polar graphene according to the invention has a content in number of nitrogen atoms relative to the total number of atoms of the graphene (with the exception of any hydrogen atoms present in the graphene) of between 0.1 and 5%, preferably between 0.1 and 2%, preferably between 0.5 and 2%.

[0114] The determination of the ratios 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”.

[0115] The specific surface area according to the BET method is between 20 and 1000 m 2 / g, preferably between 50 and 750 m 2 / g.

[0116] Polar graphene may in particular be oxidized graphene (graphene oxide in English) or graphene comprising at least one function reacting with the polyamide, in particular at least one function chosen from maleic anhydrides, carboxylic acids, primary amines, isocyanates, preferably maleic anhydrides and amines.

[0117] Polar graphene may also be reduced oxidized graphene, possibly called reduced graphene oxide. This type of graphene is obtained by reduction of oxidized graphene, resulting in a reduction of the oxygen level in the graphene. This reduction step may, for example, be carried out thermally (exposure to heat), chemically (placement in the presence of a reducing agent such as sodium borohydride NaBH4, hydroiodic acid HI, hydrazine N2H4) and / or photochemically (exposure to radiation in the presence of a photocatalyst). In one embodiment, the polar graphene comprises one or more of the functions chosen from alcohol functions, ketone functions, carboxylic acid functions, and epoxide functions.Preferably, the polar graphene comprises at least 2, advantageously at least 3 different functions chosen from alcohol functions, ketone functions, carboxylic acid functions, epoxide functions. The polar graphene preferably has an average thickness of between 0.5 and 100 nm, preferably between 1 and 100 nm, preferably between 0.5 and 75 nm, preferably between 1 and 50 nm, preferably between 1.5 and 50 nm, more preferably between 2 and 25 nm.

[0118] Polar graphene has lateral dimensions of between 0.1 and 100 pm, in particular between 0.25 and 75 pm, advantageously between 0.4 and 50 pm, preferably between 0.5 and 40 pm, more preferably between 0.5 and 10 pm.

[0119] 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. Graphene thickness and dimensions 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.

[0120] Advantageously, the graphene and the polyamide are covalently linked by an amide, ester, urea or urethane function, preferably amide.

[0121] Preferably, the composition according to the invention comprises less than 10% by weight, preferably less than 1% by weight, and preferentially less than 0.1% by weight of carbon nanotubes, relative to the total weight of the composition.

[0122] In one embodiment, the composition according to the invention is free of carbon nanotubes.

[0123] Shock modifier

[0124] The impact modifier may be present up to 40% by weight relative to the total weight of the composition.

[0125] 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.

[0126] 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%, especially from 3 to 30% by weight, preferably from 3 to 15% by weight, for example from 3 to 12% by weight, relative to the total weight of the composition.

[0127] The impact modifier is advantageously made up of a polymer having a flexural modulus of less than 100 MPa measured according to standard ISO 178: 2010, determined at 23°C with a relative humidity: RH50%, and a Tg of less than 0°C (measured according to standard 11357-2: 2013 at the inflection point of the DSC thermogram, at a heating rate of 20K / min), in particular a polyolefin.

[0128] In one embodiment, polyether block amides (PEBA) are excluded from the definition of impact modifiers.

[0129] The polyolefin of the impact modifier may be functionalized or non-functionalized or be a mixture of at least one functionalized and / or at least one non-functionalized. For simplicity, the polyolefin has been designated (B) and functionalized polyolefins (B1) and non-functionalized polyolefins (B2) have been described below.

[0130] 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. Examples include:

[0131] - homopolymers and copolymers of polyethylene, in particular LDPE, HDPE, LLDPE (linear low density polyethylene), VLDPE (very low density polyethylene) and metallocene polyethylene.

[0132] - homopolymers or copolymers of propylene.

[0133] - ethylene / alpha-olefin copolymers such as ethylene / propylene, EPR (abbreviation for ethylene-propylene-rubber) and ethylene / propylene / diene (EPDM). styrene / ethylene-butene / styrene (SEBS), styrene / butadiene / styrene (SBS), styrene / isoprene / styrene (SIS), styrene / ethylene-propylene / styrene (SEPS) block copolymers.

[0134] - copolymers of ethylene with at least one product chosen from salts or esters of unsaturated carboxylic acids such as alkyl (meth)acrylate (for example methyl acrylate), or vinyl esters of saturated carboxylic acids such as vinyl acetate (EVA), the proportion of comonomer being able to reach 40% by weight.

[0135] 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. As an example, mention may be made of the preceding polyolefins (B2) grafted or co- or terpolymerized by unsaturated epoxides such as glycidyl (meth)acrylate, or by carboxylic acids or the corresponding salts or esters such as (meth)acrylic acid (the latter being able to be neutralized totally or partially by metals such as Zn, etc.) or even by carboxylic acid anhydrides such as maleic anhydride. A functionalized polyolefin is, for example, a PE / EPR blend, the weight ratio of which can vary 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 of, for example, 0.01 to 5% by weight.

[0136] The functionalized polyolefin (B1) 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:

[0137] - PE, PP, copolymers of ethylene with propylene, butene, hexene, or octene containing for example 35 to 80% by weight of ethylene;

[0138] - ethylene / alpha-olefin copolymers such as ethylene / propylene, EPR (abbreviation for ethylene-propylene-rubber) and ethylene / propylene / diene (EPDM). styrene / ethylene-butene / styrene (SEBS), styrene / butadiene / styrene (SBS), styrene / isoprene / styrene (SIS), styrene / ethylene-propylene / styrene (SEPS) block copolymers.

[0139] - ethylene and vinyl acetate (EVA) copolymers, containing up to 40% by weight of vinyl acetate;

[0140] - ethylene and alkyl (meth)acrylate copolymers, containing up to 40% by weight of alkyl (meth)acrylate;

[0141] - ethylene vinyl acetate (EVA) and alkyl (meth)acrylate copolymers, containing up to 40% by weight of comonomers.

[0142] The functionalized polyolefin (B1) 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).

[0143] The functionalized polyolefin (B1) 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.

[0144] 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 terminomer (the function) represents, for example, from 0.1 to 10% by weight of the copolymer:

[0145] - ethylene / alkyl (meth)acrylate / (meth)acrylic acid or maleic anhydride or glycidyl methacrylate copolymers;

[0146] - ethylene / vinyl acetate / maleic anhydride or glycidyl methacrylate copolymers; - ethylene / vinyl acetate or alkyl (meth)acrylate / (meth)acrylic acid or maleic anhydride or glycidyl methacrylate copolymers.

[0147] In the above copolymers, (meth)acrylic acid can be salified with Zn or Li.

[0148] The term "alkyl (meth)acrylate" in (B1) or (B2) means C1-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.

[0149] Furthermore, the above-mentioned polyolefins (B1) can also be crosslinked by any suitable process or agent (diepoxy, diacid, peroxide, etc.); the term functionalized polyolefin also includes mixtures of the above-mentioned 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.

[0150] The above-mentioned copolymers, (B1) and (B2), can be copolymerized in a random or block manner and have a linear or branched structure.

[0151] The molecular weight, MFI index, and density of these polyolefins can also vary widely, as those skilled in the art will appreciate. MFI, short for Melt Flow Index, is the melt flow index. It is measured according to ASTM 1238.

[0152] Advantageously, the non-functionalized polyolefins (B2) are chosen from homopolymers or copolymers of polypropylene and any homopolymer of ethylene or copolymer of ethylene and a comonomer of higher alpha olefin type such as butene, hexene, octene or 4-methyl 1-pentene. Examples that may be mentioned are PP, high density PE, medium density PE, linear low density PE, low density PE, very low density PE. These polyethylenes are known to those skilled in the art as being produced according to a “radical” process, according to a “Ziegler” type catalysis or, more recently, according to a so-called “metallocene” catalysis.

[0153] 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 monoamine oligomers of polyamide.Preferably, the impact modifier of the invention, which is preferably a polyolefin as described above, has an atomic carbon content greater than 70%, preferably greater than 80%, more preferably greater than 90%, relative to the number of atoms of the polyolefin except 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.

[0154] Preferably, the impact modifier is chosen from olefin copolymers and in particular copolymers comprising ethylene or propylene units.

[0155] Additive

[0156] 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.

[0157] 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).

[0158] 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.

[0159] In the context of the present invention, the term “polycondensation catalyst” means the catalysts used for the preparation of the polyamide.

[0160] Preferably, the composition of the invention comprises as additive at least one organic or inorganic stabilizer such as phenolic, phosphite or copper-containing antioxidants.

[0161] 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.

[0162] The so-called short fibers are between 100 and 400 pm in length, preferably between 200 and 400 pm.

[0163] 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.

[0164] Mineral fibers suitable for the invention include carbon fibers, which include 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 (AI2O3); metallized fibers such as metallized glass fibers and metallized carbon fibers or mixtures of the aforementioned fibers.

[0165] More particularly, these fibers may 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 AI2O3, metallized fibers such as metallized glass fibers 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), polyetherketoneetherketone ketone (PEKEKK).,

[0166] Preferred short reinforcing fibers are short fibers selected from: carbon fibers, including metallized, glass fibers, including metallized type E, R, S2, aramid fibers (such as Kevlar®) or aromatic polyamides, polyarylether ketone (PAEK) fibers, such as polyetherether ketone (PEEK), polyetherketone ketone (PEKK) fibers, polyetherketoneetherketone ketone (PEKEKK) fibers or mixtures thereof.

[0167] Natural fibers can be chosen from linen, castor, wood, sisal, kenaf, coconut, hemp, and jute fibers.

[0168] 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.

[0169] Preferably, the composition of the invention does not comprise continuous fibers.

[0170] In a preferred embodiment, the composition of the invention does not comprise long reinforcing fibers, i.e. reinforcing fibers with a length greater than 400 μm.

[0171] Plasticizer

[0172] 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.

[0173] The plasticizers are, for example, selected 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.

[0174] It would not be outside the scope of the invention to use a mixture of plasticizers. 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.

[0175] 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.

[0176] In a particularly preferred embodiment, the composition comprises, relative to the total weight of the composition, less than 1% by weight of plasticizer, preferably less than 0.5% by weight of plasticizer.

[0177] In a particularly preferred embodiment, the composition of the invention does not comprise a plasticizer.

[0178] Particularly preferably, the present invention relates to a composition comprising, relative to the total weight of the composition:

[0179] - At least 50% by weight of at least one polyamide having an inherent viscosity greater than 1.2;

[0180] From 0.05 to 20% by weight of a polar graphene having an average thickness between 0.5 and 75 nm;

[0181] From 3 to 40% by weight of at least one impact modifier.

[0182] Method of preparing the composition

[0183] The present invention also relates to a process for preparing a composition as described above.

[0184] In a first embodiment, the process for preparing the composition according to the invention comprises the steps of:

[0185] (i) Preparation of a masterbatch by dispersing graphene in a polyamide matrix; then

[0186] (ii) Mixing the masterbatch in the polyamide according to the invention comprising the possible impact modifiers, additives and plasticizers.

[0187] Preferably, in step (i) the graphene content is 10 to 50% by weight relative to the weight of the masterbatch.

[0188] Advantageously, the polyamide of the masterbatch is identical to the polyamide of the composition according to the invention.

[0189] Preferably in step (ii) the masterbatch content is between 1 and 20% relative to the total weight of the mixture obtained in step (ii).

[0190] 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 a continuous co-kneader, or a stirred reactor. Preferably, the mixing takes place in an extruder or a co-kneader, more preferably in an extruder, even more preferably in a twin-screw extruder.

[0191] 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.

[0192] 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.

[0193] Prior to their mixing in step (ii), the masterbatch and the polyamide may independently be in powder or granule form.

[0194] 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.

[0195] 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.

[0196] In this embodiment, the preparation method comprises a step of shaping the resulting mixture 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.

[0197] This second embodiment of the process is not preferred given that it poses health risks (inhalation in particular) due to the small size of the graphene particles.

[0198] 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.

[0199] Single-layer or multi-layer structure

[0200] 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, preferably consists of the composition according to the invention.

[0201] 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.

[0202] The term “motor vehicle” means any vehicle with a thermal, electric or hybrid engine equipped with wheels or tracks, excluding a flying vehicle.

[0203] The motor vehicle may be two-wheeled, three-wheeled, four-wheeled or tracked.

[0204] For example, it is 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.

[0205] 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.

[0206] 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 at least one layer of which is made up of the composition according to the invention.

[0207] In another embodiment, the present invention relates to single- or multi-layer tubular (MLT) structures 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 of the invention.

[0208] Preferably, the multilayer structures comprise at least one further layer, preferably comprising a polyamide.

[0209] 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 reinforcement layers (in particular composite layer), sealing layers (barrier layer), chemical resistance layers, burst resistance layers, etc. These multilayer structures are well known to those skilled in the art.

[0210] The term "fluid" designates a gas, in particular used in automobiles, or a liquid, in particular used in the automotive field. Examples of liquids include an oil, a brake fluid, a urea solution, a glycol-based coolant, fuels, in particular fuels including 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.

[0211] In a preferred embodiment, air, nitrogen and oxygen are excluded from the definition of said fluid.

[0212] In one embodiment, said fluid designates fuels, in particular gasoline, in particular alcoholic gasoline.

[0213] In another embodiment, said fluid designates hydrogen.

[0214] The term "gasoline" refers to a mixture of hydrocarbons derived from the distillation of petroleum to which additives or alcohols such as methanol and ethanol may be added, with alcohols being the major components in some cases.

[0215] The term "alcohol-based gasoline" refers to gasoline to which methanol or ethanol has been added. It also refers to E95 gasoline that does not contain petroleum distillation products.

[0216] 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.

[0217] In one embodiment, the multilayer structure according to the present invention may for example be a hydrogen tank and comprises or is made up 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 one reinforcing layer. The hydrogen tanks may comprise or be made up of, for example, several sealing layers and several reinforcing layers, or one sealing layer and several reinforcing layers, or several sealing layers and one reinforcing layer or one sealing layer and one reinforcing layer. 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, the barrier layer slows down the passage of 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 that above all prevents too much gasoline from being lost into the atmosphere by diffusion, thus preventing atmospheric pollution.

[0218] 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 inner layer, formed in whole or in part from the composition according to the invention, preferably comprising at least one layer, preferably an inner 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 inner layer, formed in whole or in part from the composition according to the invention, preferably comprising at least one layer, preferably an inner 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 the transport or storage of fluid, comprising at least one layer, preferably an inner layer, formed in whole or in part from the composition according to the invention, preferably comprising at least one layer, preferably an inner layer, consisting of the composition according to the invention;a single-layer tank, for transporting or storing 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 inner layer, formed in whole or in part from the composition according to the invention, preferably comprising at least one layer, preferably an inner layer, made of the composition according to the invention and at least one other layer, preferably the other layer comprises a polyamide.;

[0219] In one embodiment, the structures of the present invention can be used for the transportation, distribution, and storage of hydrogen (H2).

[0220] In another embodiment, the structures of the present invention may be used for the transportation, distribution and storage of coolant.

[0221] In another embodiment, the structures of the present invention may be used for the transportation, distribution and storage of fuel.

[0222] 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.

[0223] 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.

[0224] Use of the composition

[0225] 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.

[0226] Use of graphene

[0227] 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, preferably 0.1 to 1.75% by weight, more preferably 0.1 to 1.5% by weight, more preferably 0.1 to 1% by weight, and even more preferably between 0.1 and 0.75% by weight, of at least one polar graphene having an average thickness of between 0.5 and 100 nm, preferably between 1 and 100 nm, preferably between 0.5 and 75 nm, preferably between 1 and 50 nm, preferably between 1.5 and 50 nm, more preferably between 2 and 25 nm, in a composition comprising at least 50% by weight ... weight of at least one polyamide having an inherent viscosity greater than 1.2, 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,preferably less than 1% by weight of plasticizer, even more preferably less than 0.1% by weight of plasticizer, preferably the composition is free of plasticizer, the percentages being given relative to the total weight of the composition, to obtain an extractable rate less than or equal to 4g / m, 2 , preferably less than or equal to 3g / m 2 .

[0228] According to a preferred embodiment, the composition comprises, relative to the total weight of polyamide, more than 50% by weight, preferably more than 70% by weight, more preferably more than 85% by weight, of aliphatic polyamide. Preferably, the composition according to the invention comprises, by weight relative to the total weight of polyamide, 100% by weight of aliphatic polyamide.

[0229] 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, preferably 0.1 to 1.75% by weight, more preferably 0.1 to 1.5% by weight, more preferably 0.1 to 1% by weight and even more preferably between 0.1 and 0.75% by weight, of at least one polar graphene having an average thickness of between 0.5 and 100 nm, preferably between 1 and 100 nm, preferably between 0.5 and 75 nm, preferably between 1 and 50 nm, preferably between 1.5 and 50 nm, more preferably between 2 and 25 nm, in a composition comprising at least 50% by weight of at least one polyamide having an inherent viscosity greater than 1.2, 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,preferably less than 1% by weight of plasticizer, even more preferably less than 0.1% by weight of plasticizer, preferably the composition is free of 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 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 polyamide mixture then the polyamide which replaces the graphene in the comparative composition is the same polyamide mixture as that of the composition according to the invention in the same relative proportions.,

[0230] Preferably, the composition preferably comprises, relative to the total weight of polyamide, more than 50% by weight, preferably more than 70% by weight, more preferably more than 85% by weight, of aliphatic polyamide. Preferably, the composition according to the invention comprises, by weight relative to the total weight of polyamide, 100% by weight of aliphatic polyamide.

[0231] In one embodiment, the extractable rate 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 rate per unit of internal tube surface area. This measurement method is described in particular in standard TL52712.

[0232] FAM B alcoholic gasoline is described in DIN 51604-1:1982, DIN 51604-2:1984 and DIN 51604-3:1984. Briefly, FAM A alcoholic gasoline 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.

[0233] The term extractable is understood to mean all compounds originating from the composition forming the layers of the monolayer or multilayer structure and which can be carried away by the fluid; examples of extractables are plasticizers, monomers, oligomers, additives, etc.

[0234] The extractable rate is measured according to the TL52712 standard. Preferably, the use of the composition according to the invention makes it possible to achieve an extractable rate less than or equal to 4 g.nr. 2 , preferably 3 g.nr 2 .

[0235] 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, preferably 0.1 to 1.75% by weight, more preferably 0.1 to 1.5% by weight, more preferably 0.1 to 1% by weight, and even more preferably between 0.1 and 0.75% by weight, of at least one polar graphene having an average thickness of between 0.5 and 100 nm, preferably between 1 and 100 nm, preferably between 0.5 and 75 nm, preferably between 1 and 50 nm, preferably between 1.5 and 50 nm, more preferably between 2 and 25 nm, in a composition comprising at least 50% by weight ... weight of at least one polyamide having an inherent viscosity greater than 1.2, 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,preferably less than 1% by weight of plasticizer, even more preferably less than 0.1% by weight of plasticizer, preferably the composition is free of 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 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 polyamide mixture then the polyamide which replaces the graphene in the comparative composition is the same polyamide mixture as that of the composition according to the invention in the same relative proportions.,

[0236] According to a preferred embodiment, the composition preferably comprises, relative to the total weight of polyamide, more than 50% by weight, preferably more than 70% by weight, more preferably more than 85% by weight, of aliphatic polyamide. Preferably, the composition according to the invention comprises, by weight relative to the total weight of polyamide, 100% by weight of aliphatic polyamide.

[0237] The permeability according to the invention is the permeability of the single-layer or multi-layer structure to the fluid.

[0238] In a particular embodiment, the measured permeability is hydrogen permeability and is measured according to ISO 15105-2 at atmospheric pressure and 60°C. Preferably, the hydrogen permeability measured according to ISO 15105-2 at atmospheric pressure and 60°C is less than 10.00 x 10 -16 mol.m / m 2 .s.Pa, preferably less than 9.50 x 10 -16 mol.m / m 2 .spa.

[0239] The definitions and contents of polyamide, graphene, impact modifier, plasticizer and additive mentioned above also apply.

[0240] The single-layer or multi-layer structures of the invention therefore have good permeability, in particular permeability to hydrogen and a low extractable rate.

[0241] Recyclable

[0242] Particularly advantageously, the structures obtained with the composition of the invention are recyclable.

[0243] The term "recyclable" means that said mono- 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 process for manufacturing a part, in particular a new mono- 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 same graphene-free composition 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 polyamide mixture then the polyamide which replaces the graphene in the comparative composition is the same polyamide mixture as that of the composition according to the invention in the same relative proportions.

[0244] Grinding is carried out according to conventional techniques of those skilled in the art to a size of 1 mm to 2 cm.

[0245] Said reuse of said used tubular structure can be carried out in a mixture or not with virgin material.

[0246] [Examples]

[0247] Unless otherwise stated, percentages are expressed by weight relative to the total weight of the composition.

[0248] The compositions described in Table 1 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.

[0249] The PA11 used is a phosphoric acid-catalyzed polyamide 11 with an acid chain end concentration of 30 peq / g and an amine chain end concentration of 33 peq / g.

[0250] The PPA used is an MXD10 PPA with an acid chain end concentration of 72 peq / g and an amine chain end concentration of 17 peq / g.

[0251] The shock modifier is Tafmer MH5020C marketed by Mitsui Chemicals.

[0252] Graphene 1 is a non-polar graphene with an average thickness of 2 nm and average lateral dimensions of 980 nm. Graphene 1 is not a graphene oxide.

[0253] Graphene 2 is a polar graphene consisting of 99 mol% carbon atoms and having an average thickness of 102 nm and average lateral dimensions of 1050 nm.

[0254] Graphene 3 is a reduced oxidized graphene comprising 6 mol% oxygen atoms relative to carbon atoms, having an average thickness of 1.6 nm and average lateral dimensions of 2300 nm. Graphene 4 is a graphene comprising 1 mol% nitrogen atoms relative to carbon atoms, having an average thickness of 1 nm and average lateral dimensions of 4300 nm.

[0255] The graphenes were added as a master batch comprising 10% by weight of graphene and 90% of polyamide (PA 11 or PPA).

[0256] The organic stabilizer used is a mixture of 80% Irganox® 1010 and 20% Irgafos® 168 from BASF.

[0257] Table 1

[0258] Liners with a thickness of 2 mm of the comparative and inventive compositions were prepared by blow-molding and the hydrogen permeability measured according to ISO 15105-2 at atmospheric pressure and at 60°C was tested on plates of dimension 100*100*2 mm cut from the prepared liners.

[0259] This test consists of sweeping the upper face of the film with the test gas (Hydrogen) and measuring by gas chromatography the flow 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.

[0260] The experimental conditions are presented in the following Table 2. Table 2

[0261] 1A specimens (according to ISO 527) and impact bars (according to ISO179) were manufactured by injection molding using a Battenfeld BA800 CDC press using unpolished molds. The following parameters were applied during injection for compositions comprising PA 11:

[0262] - Sheath temperature: 250°C

[0263] - Nozzle temperature: 270°C

[0264] - Mold temperature: 40°C

[0265] - Cycle time: 60 s

[0266] The following parameters were applied during injection for the composition comprising MXD10 (comparative example s):

[0267] - Sheath temperature: 300°C

[0268] - Nozzle temperature: 320°C

[0269] - Mold temperature: 60°C

[0270] - Cycle time: 60 s

[0271] Elongation at break is measured at 23°C on 1A specimens according to ISO527. Impact toughness at 23°C was measured according to ISO 179 1 eA. Elongation at break and impact toughness were measured after conditioning for 15 days at 23°C and 50% relative humidity.

[0272] The results are given in Table 3 Table 3

[0273] The compositions of the invention make it possible to obtain better compromises between hydrogen barrier properties and mechanical properties (elongation at break and impact).

[0274] Example 1 according to the invention makes it possible to obtain a permeability close to that of Comparative Example 1 while significantly improving impact resilience. Example 2 according to the invention makes it possible to obtain improved permeability while maintaining the level of mechanical properties.

Claims

Claims 1. Composition comprising, relative to the total weight of the composition: - At least 50% by weight of at least one polyamide having an inherent viscosity greater than 1.2; From 0.05 to 20% by weight of a polar graphene having an average thickness between 0.5 and 75 nm; From 3 to 40% by weight of at least one impact modifier.

2. Composition according to claim 1, further comprising: - Up to 5% by weight of at least one additive; and / or Less than 1% by weight of at least one plasticizer; and / or From 5 to 49% by weight of short reinforcing fibers.

3. Composition according to claim 1 or 2, in which the polar graphene is a graphene oxide or a graphene functionalized with at least one function reacting with the polyamide, preferably a function chosen from maleic anhydrides, carboxylic acids, primary amines, isocyanates, preferably maleic anhydrides and amines.

4. Composition according to any one of the preceding claims, in which the polar graphene has a number of oxygen atoms of between 0.1 and 45%, preferably between 0.5 and 10%, relative to the total number of atoms of the graphene with the exception of any hydrogen atoms present in the graphene.

5. Composition according to any one of the preceding claims in which the polyamide is: An aliphatic polyamide resulting from the polycondensation: o of at least one amino acid in C6 to C18, preferably in C9 to C18, more preferably in C10 to C18, even more preferably in C10 to C12, in particular in C11; or o at least one lactam in C6 to C18, preferably in C9 to C18, more preferably in C10 to C18, even more preferably in C10 to C12, in particular in C12; or o at least one aliphatic diamine Ca in C4-C36, in particular in C6-C36, preferably C6-C18, preferably C6-C12, more preferably C10-C12 with at least one aliphatic diacid Cb in C4-C36, in particular in C6-C36, preferably C6-C18, preferably C10-C18, more preferably C10-C12; or A semi-aromatic polyamide of formula A / XT in which A is selected from a unit obtained from an amino acid, a unit obtained from a lactam and a unit corresponding to the formula (Ce diamine). (Cd diacid), with c representing the number of carbon atoms of the diamine and d representing the number of carbon atoms of the diacid, c and d each being between 4 and 36, advantageously between 9 and 18, the unit (Ce diamine) being selected from linear or branched aliphatic diamines, as defined above, cycloaliphatic diamines and alkylaromatic diamines and the unit (Cd diacid) being selected from linear or branched aliphatic diacids, cycloaliphatic diacids and aromatic diacids; X.T denotes a unit obtained from the polycondensation of a Cx diamine and terephthalic acid, with x representing the number of carbon atoms of the Cx diamine, x being between 5 and 36, advantageously between 9 and 18, T corresponds to terephthalic acid.

6. Composition according to any one of the preceding claims in which the polyamide is: An aliphatic polyamide selected from PA6, PA66, PA11, PA12, PA610, PA612, PA1010, PA1012 and PA1212; A semi-aromatic polyamide selected from 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 11 / MXDT / 10T, 11 / 5T / 10T, T is terephthalic acid, MXD is m-xylylenediamine, MPMD is methylpentamethylenediamine and BAC is bis(aminomethyl)cyclohexane.

7. Composition according to any one of the preceding claims comprising, relative to the total weight of polyamide - at least 50%, preferably at least 70%, more preferably at least 85% by weight of aliphatic polyamide.

8. Composition according to any one of the preceding claims in which the graphene content is between 0.1 and 1.75% by weight relative to the total weight of the composition.

9. Composition according to any one of the preceding claims in which the impact modifier is chosen from olefin copolymers and in particular copolymers comprising ethylene or propylene units.

10. Single-layer or multi-layer structure 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 as defined in any one of claims 1 to 9.

11. Structure according to claim 10 characterized in that it is a tubular structure.

12. Structure according to claim 10 characterized in that it is a reservoir.

13. Use of the structure according to one of claims 10 to 12 for the transport, distribution and storage of a fluid.

14. Use according to claim 13, wherein the fluid is hydrogen.

15. Use according to claim 13, wherein the fluid is a coolant.

16. Use according to claim 13, wherein the fluid is a fuel.

17. Use of a composition according to any one of claims 1 to 9 for the manufacture of a single-layer or multi-layer structure by injection, extrusion, extrusion-blow molding or rotational molding, preferably by extrusion.

18. Use of 0.05 to 20% by weight of at least one polar graphene having an average thickness of between 0.5 and 75 nm in a composition comprising at least 50% by weight of at least one polyamide having an inherent viscosity greater than 1.2, 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 less than 1% by weight of at least one plasticizer, the percentages being given relative to the total weight of the composition, to obtain an extractable rate of less than or equal to 4g / m 2 , preferably less than or equal to 3g / m 2 .

19. Use of 0.05 to 20% by weight of at least one polar graphene having an average thickness of between 0.5 and 75 nm in a composition comprising at least 50% by weight of at least one polyamide having an inherent viscosity greater than 1.2, 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 less than 1% 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 which the graphene has been replaced by the same quantity of the polyamide.

20. Use of 0.05 to 20% by weight of at least one polar graphene having an average thickness of between 0.5 and 75 nm, in a composition comprising at least 50% by weight of at least one polyamide having an inherent viscosity greater than 1.2, 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 less than 1% 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 which the graphene has been replaced by the same quantity of the polyamide.

21. Method for manufacturing a single-layer or multi-layer structure as defined according to one of claims 10 to 12, characterized in that it comprises a step of manufacturing a sealing layer by injection, extrusion, extrusion-blow molding or rotational molding.

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