Barrier layer based on mpmd.t units

Abstract

The invention relates to a polyamide (PA), the recurring units (RPA) of which are formed from the polycondensation of a diamine component (A) and a diacid component (B), wherein: - the diamine component (A) consists essentially of or consists of: - between 50.0 mol% (this value being excluded) and 70.0 mol% of 2-methylpentanediamine (MPMD); and - between 30.0 and 50.0 mol% of at least one other diamine (DA) of formula 2HN-R1-NH2 where R1 is a C8-C11 linear or branched alkylene group; - these proportions in mol% being based on the total amount of diamines in the diamine component (A); - the diacid component (B) consists essentially of or consists of: - between 90.0 and 100.0 mol.% of terephthalic acid; and - between 0 and 10.0 mol.% of another diacid (DI) selected in the group consisting of isophthalic acid, adipic acid (AA) and a combination thereof; - these proportions in mol% being based on the total amount of diacids in the dicarboxylic acid component (B); - wherein the proportion of MPMD.T recurring units in the polyamide (PA) are greater than 50.0 mol% (> 50.0 mol%), this proportion being given relative to the total number of moles of recurring units in the polyamide (PA).

Description

BARRIER LAYER BASED ON MPMD.T UNITSThis international application claims priority of US patent application No. 63 / 579725 filed on 30 August 2023 and European patent application No. 23196801.7 filed on 12 September 2023, the content of which being entirely incorporated herein by reference for all purposes. In case of any incoherency between this international application and the two priority applications that would affect the clarity of a term or expression, it should be made reference to the PCT application only.[FIELD OF THE INVENTION]

[0001] The invention relates to a novel semi-aromatic polyamide based on 2- methylpentanediamine (MPMD) and its use as a barrier for H2 and to a multilayer structure comprising said polyamide.[BACKGROUND OF THE INVENTION]

[0002] In recent years, environmentally-friendly natural gas vehicles and fuel cell vehicles have become more widespread. Fuel cell vehicles are powered by fuel cells in which hydrogen is used as a fuel.

[0003] With the requirement to decrease the weight of the vehicles, tanks of H2 based on composite materials are preferred over tanks made of steel. These tanks need to withstand the internal pressure of H2 and the loss of H2 over time should be minimized.

[0004] High-pressure gas storage tanks comprising a liner having barrier properties and an outer layer comprising a fiber-reinforced composite material have been developed to address this need. Type IV tanks have thus been developed. These tanks are made of thermoplastic liner wrapped with a composite material.

[0005] For instance, US 2023 / 0142635 discloses such a high-pressure gas storage tank wherein the liner is made of a thermoplastic polymer, notably a polyamide as disclosed in WO 2016 / 084175.

[0006] JP 2023 / 058318 discloses a hydrogen tank liner that is excellent in gas barrier properties against hydrogen which is formed of a resin composition containing a copolymer containing a conjugated diene unit, a non-conjugated olefin unit, and an aromatic vinyl unit.

[0007] KR 102493982 Bl discloses a polymeric film for a hydrogen tank liner comprising a copolymer comprising a polyamide-based segment and a polyether-based segment.

[0008] US 5,302,691 discloses copolyamides based on a diamine component comprising MPMD and 1,6-hexamethylenediamine.

[0009] WO 2017 / 102385 discloses a pressure vessel comprising a hollow body comprising endless fibers embedded in a thermoplastic matrix based. There is no disclosure of the polyamide of the invention.

[0010] WO 2022 / 069826 discloses a multilayer structure intended to contain hydrogen comprising from the inside to the outside at least one barrier layer and at least one reinforcing layer, the barrier layer comprising from 20.5 to 99.845 wt% of a polyamide, from 0.005 to 0.5 wt% of a catalyst, from 0.05 to 1 wt% of a heat stabilizer and from 0.1 to 3 wt% of an oligo- or polycarbodimide. The polyamide of said barrier layer may be selected in the group consisting of PA 10.10, PA 10.12, PA 11, PA12, 11 / 5T, 11.6T, 11.10T, MXD.T / 10.T, MPMD.T / 10.T and BAC.T / 10.T. There is no disclosure of the copolyamide of claim 1.

[0011] US 6,162,317 (DI) discloses in Table 2 several copolyamides based on MPMD and on 1,6-hexanediamine (C6).

[0012] US 2023 / 0151255 (D2) discloses the use of a sealing layer consisting of a composition comprising at least one polyamide for preparing a multilayer structure intended for the transport, the distribution or the storage of hydrogen, said sealing layer being based on a polyamide selected in the group consisting of 11 / 5T, 11 / 6T, 11 / 10T, MXDT / 10T, MPMD.T / 10.T and BAC.T / 10.T. There is no disclosure of the copolyamide of claim 1.

[0013] WO 2023 / 083783 discloses a multilayer structure for storing or transporting H2 comprising a sealing layer made of MPMD.T / 10.T with a Tg of 125°C. There is no disclosure of the copolyamide of claim 1.

[0014] US 11,345,131 discloses a barrier structure chosen from bottles, tanks, pipes comprising a barrier layer comprising a MPMD.T / X.T copolyamide with the following proportions: from 5 to 50 mol% of MPMD. T units and from 50 to 95 mol% of X.T units. In particular, the sole example of US'131 discloses a polyamide with 41 mol% of MPMD. T units and 59 mol% of 10. T units. The polyamide of the invention differs in that the proportions of MPMD. T units is strictly higher than 50.0 mol%.

[0015] US 8,338,561 B2 discloses a polyamide having a melting point Tm between 330° C and 370°C, comprising a diamine component (a) comprising of at least 22 mole % and at most 28 mole %, of at least one aliphatic diamine having more than 6 carbon atomsselected from 1,9-nonanediamine and 2-methyl-l,8-octanediamine, and at least 72 mole% and at most 78 mole %, based on the total number of moles of the diamine component (a), of 1,6-hexanediamine, and a dicarboxylic acid component (b) consisting essentially of terephthalic acid.

[0016] GB 1383757 discloses a polyamide which comprises condensing a mixture of 2- methyl-pentamethylene diamine and l,3-bis-(aminomethyl)-cyclohexane, which latter can, if desired, be partially replaced by l,4-bis-(aminomethyl)-cyclohexane, the proportion of the 2-methyl-pentamethylene-diamine being in the range of 20 to 80 mol %, preferably from 40 to 60 mol %, based on the total amount of diamine, with an aromatic dicarboxylic acid having from 7 to 20 carbon atoms, preferably from 8 to 14 carbon atoms, advantageously a mono-nuclear dicarboxylic acid carrying the carboxylic groups in meta- or para- position, or a mixture of two or more of these acids.

[0017] JP 2014 / 240148 discloses an electroconductive laminate tube consisting of at least three layers including: a layer consisting of an aliphatic polyamide; a layer consisting of a semi-aromatic polyamide having a specified structure consisting of diamine units including at least 80% of C9-C13 aliphatic diamine units and dicarboxylic acid units including at least 80% of terephthalic acid units and / or naphthalenedicarboxylic acid units; and a layer consisting of an electroconductive semi-aromatic polyamide copolymer composition consisting of: a semi-aromatic polyamide copolymer having a specified structure; and an electroconductive filler. The following semi-aromatic polyamide containing 20 mol% of MPMD.T units is disclosed: 9T / M8T / 6T / M5T=30 / 30 / 20 / 20 mol% having a melting temperature of 217°C.[TECHNICAL PROBLEM]

[0018] There is the need of a thermoplastic polymer exhibiting good barrier properties towards H2 (low permeability) even at high temperatures while being easily processable into a liner, notably by extrusion. Moreover, the thermoplastic polymer should exhibit a combination of thermal properties: a high glass transition temperature Tg for withstanding high temperatures, a low melting temperature Tm for processability and a low crystallization temperature Tc for easier processing.

[0019] The polyamide of the invention aims at solving this technical problem.[BRIEF DISCLOSURE OF THE INVENTION]

[0020] The invention is notably disclosed in the appended claims.

[0021] The invention relates to a polyamide as disclosed in any one of claims 1-20.

[0022] The invention also relates to a process of preparation of a polyamide as disclosed in claims 21 or 22.

[0023] The invention also relates to a polymer composition as disclosed in any one of claims 23-27.

[0024] The invention also relates to a use as disclosed in claims 28 or 29.

[0025] The invention also relates to a hydrogen barrier layer as disclosed in any one of claims 30-32.

[0026] The invention also relates to a multilayer structure intended to store or transport H2 as disclosed in any one of claims 33-36.

[0027] The invention also relates to a vessel or a pipe as disclosed in claim 37.

[0028] The invention also relates to a thermoplastic composite as in claim 38.

[0029] More precisions and details about these subject-matters are now provided below.[DEFINITIONS]

[0030] wt% means % by weight. mol% means % by mole.

[0031] In all numerical ranges (also in those without upper or lower end points), unless otherwise indicated, the end-points are included.

[0032] In the present application, unless otherwise indicated, any specific embodiment or technical feature relating to a subject-matter is applicable to and interchangeable with another embodiment or technical feature also relating to the same subject-matter and disclosed elsewhere in the application.

[0033] The proportions of diamines in the diamine component (A) are given in mol% and relative to the total amount of diamines in the diamine component (A).

[0034] The proportions of dicarboxylic acids in the dicarboxylic acid component (B) are given in mol% and relative to the total amount of dicarboxylic acids - also referred to as diacids - in the dicarboxylic acid component (B).

[0035] A dicarboxylic acid is an organic compound that contains two functional carboxylic acid (-COOH) groups. Terephthalic acid, isophthalic acid and adipic acid are examples of dicarboxylic acids.

[0036] The proportions of recurring units in the polyamide are expressed in mol% and relative to the total amount of recurring units.[DETAILED DESCRIPTION OF THE INVENTION]

[0037] As a first aspect, the invention relates to a polyamide (PA), the recurring units (RPA) of which are formed from the polycondensation of a diamine component (A) and a dicarboxylic acid component (B), wherein:- the diamine component (A) comprises, consists essentially of or consists of■ between 50.0 mol% (this value being excluded) and 70.0 mol% of 2- methylpentanediamine (MPMD); and■ between 30.0 and 50.0 mol% of at least one other diamine (DA) of formula 2HN-R1-NH2 where Ri is a Cs-Cn linear or branched alkylene group;■ these proportions in mol% being based on the total amount of diamines in the diamine component (A);- the dicarboxylic acid component (B) comprises, consists essentially of or consists of■ between 90.0 and 100.0 mol.% of terephthalic acid; and■ between 0 and 10.0 mol.% of another diacid (DI) selected in the group consisting of isophthalic acid, adipic acid (AA) and a combination thereof;■ these proportions in mol% being based on the total amount of dicarboxylic acids in the dicarboxylic acid component (B);- wherein the proportion of MPMD. T recurring units in the polyamide (PA) are greater than 50.0 mol% (> 50.0 mol%), this proportion being given relative to the total number of moles of recurring units in the polyamide (PA).

[0038] All monomers of the diamine component (A) and dicarboxylic acid component (B) are substantially present in the polyamide in polymerized form.

[0039] Diamine component (A)

[0040] The diamine component (A) comprises, consists essentially of or consists of between 50.0 mol% (this value being excluded) and 70.0 mol% of 2-methylpentanediamine (MPMD) and between 30.0 and 50.0 mol% of at least one other diamine (DA) of formula 2HN-R1-NH2 where Ri is a Cs-Cn linear or branched alkylene group. The diamine component (A) more particularly consists essentially of or consists of between 50.0 mol% (this value being excluded) and 70.0 mol% of 2- methylpentanediamine (MPMD) and between 30.0 and 50.0 mol% of at least one other diamine (DA) of formula 2HN-R1-NH2 where Ri is a Cs-Cn linear or branched alkylene group. These proportions in mol% are based on the total amount of diamines in the diamine component (A).

[0041] The expression "consist essentially" means in the context of the invention in relation to the diamine component that the diamine component (A) consists of MPMD, at least one diamine (DA) and up to 1.0 mol%, more preferably up to 0.5 mol%, of one or more diamines other than MPMD and diamine (DA), this proportion in mol% being based on the total amount of diamines in the diamine component (A).

[0042] MPMD (or 2-methylpentane-l,5-diamine) is the diamine of formula:number: 15520-10-2]

[0043] Diamine (DA) is of formula 2HN-R1-NH2 where Ri is a Cs-Cn linear or branched alkylene group.

[0044] The proportion of the other diamine(s) (DA) of formula 2HN-R1-NH2 where Ri is a Cs-Cn linear or branched alkylene group is between 30.0 and 50.0 mol%. This proportion in mol% is based on the total amount of diamines in the diamine component (A).

[0045] The proportion of MPMD and the total proportion of diamine(s) (DA) may more particularly be respectively between 53.0 and 63.0 mol% and 37.0 and 47.0 mol%.

[0046] Ri is more particularly a Cs-Cio linear or branched alkylene group.

[0047] Ri is more particularly a Cs-Cio linear alkylene group.

[0048] Diamine (DA) may more particularly be selected in the group consisting of 1,8- octanediamine, 1,9-diaminononane, 1,10-diaminodecane, 2-methyl-l,8- octanediamine and combination of two or more of these diamines. If diamine (DA) corresponds to the combination of 2-methyl-l,8-octanediamine and at least one diamine selected in the group consisting of 1,8-octanediamine, 1,9-diaminononane,1.10-diaminodecane, the proportion of 2-methyl- 1,8-octanediamine in the diamine component (A) is preferably lower than or equal to 10.0 mol% (< 10.0 mol%), more preferably lower than or equal to 5.0 mol% (< 5.0 mol%).

[0049] Diamine (DA) may more particularly be selected in the group consisting of 1,8- octanediamine, 1,9-diaminononane, 1,10-diaminodecane and combination of two or more of these diamines.

[0050] Diamine (DA) may more particularly be selected in the group consisting of 1,9- diaminononane, 1,10-diaminodecane and combination of 1,9-diaminononane and1.10-diaminodecane (2HN-(CH2)IO-NH2)..

[0051] Diamine (DA) may more particularly be 1,9-diaminononane (2HN-(CH2)9-NH2).

[0052] Diamine (DA) may be any one of the diamines in the lists disclosed herein.

[0053] Dicarboxylic acid component (B)

[0054] The dicarboxylic acid component (B) comprises, consists essentially of or consists of between 90.0 and 100.0 mol% of terephthalic acid; and between 0 and 10.0 mol.% of another diacid (DI) selected in the group consisting of isophthalic acid, adipic acid (AA) and a combination thereof. The dicarboxylic acid component (B) more particularly consists essentially of or consists of between 90.0 and 100.0 mol% of terephthalic acid; and between 0 and 10.0 mol.% of another diacid (DI) selected in the group consisting of isophthalic acid, adipic acid (AA) and a combination thereof. These proportions in mol% are based on the total amount of diacids in the dicarboxylic acid component (B).

[0055] Diacid (DI) may be isophthalic acid or adipic acid or a combination of isophthalic acid and adipic acid.

[0056] The expression "consist essentially" means in the context of the invention in relation to the dicarboxylic acid component that the dicarboxylic acid component (B) consists of terephthalic acid, optionally of another diacid (DI) selected in the group consisting of isophthalic acid, adipic acid (AA) and a combination thereof and up to 1.0 mol%, more preferably up to 0.5 mol%, of one or more diacids other than terephthalic acid and diacid(s) (DI), this proportion in mol% being based on the total amount of dicarboxylic acids in the dicarboxylic acid component (B).

[0057] The proportion of terephthalic acid and the total proportion of diacid(s) (DI) may more particularly be respectively between 95.0 and 100.0 mol% and between 0 and 5.0 mol%; preferably respectively between 97.0 and 100.0 mol% and between 0 and 3.0 mol%; preferably respectively between 99.0 and 100.0 mol% and between 0 and 1.0 mol%.

[0058] According to a preferred embodiment (E), the dicarboxylic acid component (B) consists essentially of or consists of terephthalic acid. The expression "consist essentially" means here that the dicarboxylic acid component (B) consists of terephthalic acid and up to 1.0 mol%, more preferably up to 0.5 mol%, of one or more diacids other than terephthalic acid, this proportion in mol% being based on the total amount of di carboxylic acids in the di carboxylic acid component (B).

[0059] The copolyamide (PA) of the invention is notably selected in the group of MPMD.T / 10. T and MPMD.T / 9.T copolyamides.

[0060] Recurring units (RPA)

[0061] The recurring units (RPA) of the polyamide (PA) consist essentially or consist of the following units:

[0001] The expression "consist essentially" means in the context of the invention in relation to the recurring units that the recurring units of polyamide (PA) consist of recurring units (RPAI)-(RPA4) and up to 1.0 mol%, more preferably up to 0.50 mol%, more preferably up to 0.25 mol%, more preferably up to 0.10 mol%, of recurring units other than said recurring units, this proportion in mol% being based on the total amount of recurring units in the polyamide (PA).

[0002] As is visible for (RPAI) in the table above, MPMD is an asymmetric molecule, so that the recurring units derived from this diamine may be according to two configurations.

[0003] The proportion of units (RPAI) in polyamide (PA) is >50.0 mol%.

[0004] According to preferred embodiment (E), the recurring units of polyamide (PA) consist essentially of or consist of units (RPAI) and (RPA2). The proportions of these two units correspond to the proportions of MPMD and diamine (DA) as disclosed herein. Therefore, the proportion of (RPAI) is between 50.0 mol% (this value being excluded) and 70.0 mol% and the proportion of (RPA2) is between 30.0 and 50.0 mol%. More particularly, the proportion of (RPAI) is between 53.0 mol% and 63.0 mol% and the proportion of (RPA2) is between 37.0 and 47.0 mol%.

[0005] The polyamide (PA) is (i) preferably free of or (ii) preferably does not comprise recurring units derived from 1,6-hexam ethylene diamine.

[0006] The polyamide (PA) is (i) preferably free of or (ii) preferably does not comprise recurring units derived from 2-methyl-l,8-octanediamine.

[0007] The polyamide (PA) is (i) preferably free of or (ii) preferably does not comprise recurring units derived from m-xylylenediamine or p-xylylenediamine.

[0008] The polyamide (PA) is (i) preferably free of or (ii) preferably does not comprise recurring units derived from l,3-bis(aminomethyl)cyclohexane or 1,4- bis(aminomethyl)cyclohexane.

[0009] The polyamide (PA) is (i) preferably free of or (ii) preferably does not comprise recurring units derived from a lactam or an amino-acid.

[0010] The expression “free of” in relation to specific recurring units means that the proportion of said recurring units in polyamide (PA) is lower than or equal to 1.0 mol% (< 1.0 mol%), preferably lower than or equal to 0.50 mol% (< 0.50 mol%), preferably lower than or equal to 0.25 mol% (< 0.25 mol%), preferably lower than or equal to 0.10 mol% (< 0.10 mol%).

[0011] End-groups of the polyamide (PA)

[0012] The end-groups of the polyamide (PA) are selected in the group of -NEE, -COOH and amide end-groups. Indeed, the end-groups in the polyamide (PA) may be -NH2 or - COOH. Yet, when the polycondensation involves the addition of an end-capping agent, these end-groups may be converted, partially or totally, into amide end-groups.

[0013] The amide end groups are of formula -NH-C(=O)-R where R is an alkyl group, an aryl group or a cycloalkyl group and / or of formula -C(=O)-NH-R' where R' is an alkyl group or a cycloalkyl group. R is more particularly a linear or branched Ci-Cis alkyl group or a C5-C10 cycloalkyl group. R' is more particularly a linear or branched C2- Ci8 alkyl group.

[0014] The amide end groups of formula -NH-C(=O)-R result from the reaction of the end- groups -NH2 with a monocarboxylic acid (end-capping agent) of formula R-COOH.

[0015] The monocarboxylic acid (end-capping agent) may advantageously be selected in the group consisting of benzoic acid; cyclohexanoic acid; R-COOH where R is a linear or branched Ci-Cis alkyl group and combination of two or more of these acids. R is the radical derived from the acid of formula R-COOH.

[0016] The monocarboxylic acid (end-capping agent) may more particularly be selected in the group consisting of acetic acid, propanoic acid, butyric acid, valeric acid, caproicacid, lauric acid, stearic acid, 2-ethylhexanoic acid, cyclohexanoic acid, benzoic acid and combination of two or more of these acids.

[0017] The monocarboxylic acid (end-capping agent) is more particularly of formula CH3- (CH2)m-COOH where m is an integer between 0 and 16. The amide end groups are then of formula -NH-C(=O)-(CH2)m-CH3.

[0018] The amide end groups of formula -C(=O)-NH-R' result from the reaction of the end- groups -COOH with a primary amine (end-capping agent) of formula R'-NH2.

[0019] The primary amine (end-capping agent) may advantageously be selected in the group consisting of the amines of formula R-NH2 where R' is a linear or branched C2-C18 alkyl group. R' is the radical derived from the amine of formula R-NH2.

[0020] The primary amine (end-capping agent) is more particularly of formula CH3-(CH2)m- NH2 where m' is an integer between 2 and 18. The amide end groups are then of formula -C(=O)-NH-(CH2)m-CH3.

[0021] The primary amine (end capping agent) may more particularly be selected in the group consisting of propyl amine, butylamine, pentylamine, hexylamine, 2- ethylhexylamine, n-octylamine, n-dodecylamine, n-tetradecylamine, n- hexadecylamine, stearylamine, cyclohexylamine and combination of two or more of these amines.

[0022] The proportion of the end groups can be quantified byJH NMR spectroscopy or by potentiometric techniques.

[0062] Properties of polyamide (PA)

[0063] The polyamide (PA) of the invention generally has a number average molecular weight ("Mn") ranging from 1,000 g / mol to 40,000 g / mol, for example from 2,000 g / mol to 35,000 g / mol, from 4,000 to 30,000 g / mol, or from 5,000 g / mol to 20,000 g / mol. Mn can be determined using the following equation (1): Mn = 2,000,000 / [EG] (1) wherein [EG] is the proportion of end-groups in the PA expressed in mmol / kg.

[0064] Polyamide (PA) preferably exhibits an inherent viscosity (IV) of at least 0.9 dL / g, the IV being measured according to ASTM D5336 - 22 with the use of a mixture phenol / 1, 1, 2, 2-tri chloroethane (60 / 40 wt. ratio). To be noted, this mixture is commercialized by Sigma-Aldrich(https: / / www.sigmaaldrich.com / FR / fr / product / aldrich / 33514).

[0065] IV is generally between 0.9 and 1.3 dL / g (measured in the same conditions).

[0066] Glass transition temperature (Tg)

[0067] The polyamide exhibits a Tg of at least 115°C. The Tg of the polyamide (PA) is preferably at least 120°C, preferably at least 125°C. Tg is preferably strictly higher than 125°C (> 125°C).

[0068] The polyamide (PA) generally exhibits a Tg of at most 150°C.

[0069] The Tg may more particularly be between 115°C and 150°C.

[0070] Tg is measured by Differential Scanning Calorimetry (“DSC”) according to ASTM D3418, notably using a heating and cooling rate of 20°C / min.

[0071] Tg can more particularly be measured as described in the experimental section.

[0072] Tg can be measured by Differential Scanning Calorimetry (“DSC”) according to ASTM D3418 using a heating and cooling rate of 20°C / min. Three scans are used for each DSC test: a first heat up to 350°C, followed by a first cool down to 30°C, followed by a second heat up to 360°C. The Tg is determined from the second heat up.

[0073] Melting point (Tm)

[0074] The polyamide (PA) exhibits a Tm of at most 270 °C. The Tm is preferably at most 250 °C, preferably at most 245°C.

[0075] Tm is generally at least 230°C. Tm is preferably at least 238°C.

[0076] The Tm may be between 230°C and 270°C.

[0077] Tm is measured by Differential Scanning Calorimetry (“DSC”) according to ASTM D3418, notably using a heating and cooling rate of 20°C / min.

[0078] Tm can more particularly be measured as described in the experimental section.

[0079] Tm can be measured by Differential Scanning Calorimetry (“DSC”) according to ASTM D3418 using a heating and cooling rate of 20°C / min. Three scans are used for each DSC test: a first heat up to 350°C, followed by a first cool down to 30°C, followed by a second heat up to 360°C. Tm is determined from the second heat up.

[0080] Crystallization temperature (Tc)

[0081] Polyamide (PA) exhibits a Tc of at most 200 °C. Tc is preferably at most 190 °C.

[0082] Tc is generally at least 170°C.

[0083] The Tm may be between 170°C and 200°C.

[0084] Tc is measured by Differential Scanning Calorimetry (“DSC”) according to ASTM D3418, notably using a heating and cooling rate of 20°C / min.

[0085] Tc can be measured by Differential Scanning Calorimetry (“DSC”) according to ASTM D3418 using a heating and cooling rate of 20°C / min. Three scans are used foreach DSC test: a first heat up to 350°C, followed by a first cool down to 30°C, followed by a second heat up to 360°C. Tc is determined from the first cool down.

[0086] Heat of fusion (Hm)

[0087] The polyamide (PA) is semi-crystalline.

[0088] The polyamide (PA) exhibits a Hm of at least 20.0 J / g, preferably at least 25.0 J / g.

[0089] Hm is generally at most 50.0 J / g.

[0090] Hm may be between 20.0 J / g and 50.0 J / g.

[0091] Hm is measured by Differential Scanning Calorimetry (“DSC”) according to ASTM D3418, notably using a heating and cooling rate of 20°C / min.

[0092] Hm can more particularly be measured as described in the Experimental Section.

[0093] Hm can be measured by Differential Scanning Calorimetry (“DSC”) according to ASTM D3418 using a heating and cooling rate of 20°C / min. Three scans are used for each DSC test: a first heat up to 350°C, followed by a first cool down to 30°C, followed by a second heat up to 360°C. The Hm is measured from the second heat up.

[0094] In the context of the invention, Tm, Tg, Tc and Hm of polyamide (PA) can be measured according to the protocol disclosed in the Experimental Section.

[0095] Process of preparation of polyamide (PA)

[0096] The polyamide (PA) described herein can be prepared by any conventional method adapted to the synthesis of polyamides and polyphthalamides. Polyamide (PA) is prepared by a method as claimed.

[0097] The polyamide (PA) is prepared by polycondensation by heating a reaction mixture (RM) comprising the monomers, preferably in the presence of less than 60 wt.% of water, preferentially less than 30 wt.%, preferably less than 20 wt.%, preferably less than 10 wt.%, this proportion being based on the total weight of the reaction mixture, preferentially with no added water.

[0098] The polyamide (PA) is more particularly prepared by polycondensation by heating a reaction mixture (RM) comprising, consisting essentially of or consisting of:- a mixture of monomers (MM) comprising, consisting essentially of or consisting of the diamine component (A) and the dicarboxylic acid component (B);- optionally a catalyst, notably selected in the group consisting of phosphorous acid, ortho-phosphoric acid, meta-phosphoric acid, alkali-metal hypophosphite such as sodium hypophosphite and phenylphosphinic acid;- optionally at least one capping agent;- optionally water in a proportion which is preferably less than 80.0 wt.%, preferably less than 50.0 wt.% water, this proportion of water being based on the total weight of the reaction mixture (RM).

[0099] The reaction mixture (RM) contains a mixture of monomers (MM) comprising all diamines and all dicarboxylic acids as monomers of the polyamide (PA). The monomer mixture (MM) is preferably free of any lactam or any aminoacid, the expression “free of” meaning that the total proportion of lactam(s) and the total proportion of aminoacid(s) are each lower than or equal to 1.0 wt% (< 1.0 wt%), these proportions being expressed relative to the total weight of mixture (MM). Said proportion of lactam(s) is preferably lower than or equal to 0.5 wt% (< 0.5 wt%), preferably lower than or equal to 0.1 wt% (< 0.1 wt%), preferably lower than or equal to 0.05 wt% (< 0.05 wt%). Said proportion of aminoacid(s) is preferably lower than or equal to 0.5 wt% (< 0.5 wt%), preferably lower than or equal to 0.1 wt% (< 0.1 wt%), preferably lower than or equal to 0.05 wt% (< 0.05 wt%).

[0100] As is well known in polycondensation, the reaction mixture comprises the abovereferenced diamines and diacids in a quantity such that the proportion of -COOH groups from the diacids and the proportion of -NH2 groups from the diamines are substantially equimolar. The ratio -NH2 / -COOH, notably the ratio -NH2 from the diamines of the diamine component (A) / -COOH from the dicarboxylic acids of the dicarboxylic acid component (B), is typically comprised between 0.9 to 1.1, preferentially 0.95 to 1.05, even more preferentially between 0.98 to 1.02.

[0101] The reaction mixture (RM) typically comprises a catalyst. The catalyst may be selected in the group consisting of phosphorous acid, ortho-phosphoric acid, metaphosphoric acid, alkali-metal hypophosphite such as sodium hypophosphite and phenylphosphinic acid. A convenient catalyst used is phosphorous acid.

[0102] For control of the molecular weight of the polyamide (PA), the reaction mixture (RM) may also further comprise at least one end-capping agent, notably as disclosed above.

[0103] The end-capping agent that can be used in the polycondensation process is selected in the group of monocarboxylic acids of formula R-COOH, primary amine of formula R'-NH2 and combination thereof, R and R’ being as disclosed herein.

[0104] The end-capping agent that can be used in the polycondensation process may be selected in one or more lists disclosed herein or may be any one of the end-capping agents disclosed herein.

[0105] The temperature at which the reaction mixture (RM) is heated must be high enough to induce the reaction between the amine groups of the diamines and the carboxylic groups of the dicarboxylic acids and to decrease the viscosity of the reaction mixture. This temperature is generally at least 140°C, preferably at least 200°C. The polycondensation results in the formation of the amide bonds and the release of water as a by-product.

[0106] The temperature can be step-wise increased in the course of the polycondensation. An example of step-wise increase is given in example 1 and may be followed for the preparation of the polyamide (PA) of the invention.

[0107] The polycondensation is advantageously performed in a well stirred vessel equipped with means to remove the volatile products of the reaction. As the viscosity of the reaction mixture increases over time, the stirrer is adapted to provide sufficient stirring to the reaction mixture at the beginning of the polymerization and when the conversion of the polycondensation is nearly complete.

[0108] The experimental conditions disclosed in the experimental section may conveniently be used for the preparation of the polyamide (PA).

[0109] Polyamide (PA) may be part of a polymer composition (PC) or a thermoplastic composite (TPC). Details are provided below.

[0110] Polymer composition (PC)

[0111] The invention also relates to a polymer composition (PC) comprising at least 50.0 wt% of at least one polyamide (PA) as disclosed herein and optionally at most 20.0 wt% of at least one inorganic filler and / or at least one plastic additive other than inorganic filler, this proportion being based on the total weight of the polymer composition (PC), the components of polymer composition (PC) being preferably blended together.

[0112] The inorganic filler is typically selected in the group consisting of talc, clay, mica, kaolin, calcium carbonate, calcium silicate, magnesium carbonate, glass fibers, carbon fibers and combinations thereof.

[0113] The inorganic filler may more particularly be a clay. The clay may be selected in the group consisting of montmorillonite, hectorite, saponite, vermiculite and combination of two or more of said clays.

[0114] The plastic additive other than inorganic filler is typically selected in the group consisting of tougheners, plasticizers, colorants, pigments, antistatic agents, dyes,lubricants, thermal stabilizers, light stabilizers, flame retardants, nucleating agents, antioxidants, UV absorbers, acid scavengers and combinations thereof.

[0115] The polymer composition (PC) may comprise at least one aliphatic polyamide. The proportion of the aliphatic polyamide(s) in the polymer composition (PC) is typically at least 10.0 wt%, this proportion being based on the total weight of the polymer composition (PC).

[0116] The total proportion of fillers and plastic additives in the polymer composition (PC) may be 20.0 wt% or less, even 15.0 wt% of less, even 10.0 wt% or less, even 5.0 wt% or less with respect to the total weight of polymer composition (PC). When present the one or more additives is at least 0.1 wt%, even at least 0.5 wt%, relative to the total weight of polymer composition (PC).

[0117] The proportion of polyamide(s) (PA) in the polymer composition (PC) is preferably at least 95.0 wt%, preferably at least 97.0 wt%, preferably at least 99.0 wt%.

[0118] The polymer composition (PC) is prepared by a method Ml comprising a step in which the components of the polymer composition (PC) are introduced into a mixer, such as single screw extruder or twin screw extruder, agitator, single screw or twin screw kneader or Banbury mixer. The mixer is conveniently an extruder.

[0119] Method Ml comprises at least one step wherein the polymer composition (PC) is in the molten form.

[0120] Method Ml ensures with the use of a mixer as disclosed ensures that the plastic additive(s) and / or the filler(s) are blended with the polyamide(s) (PA).

[0121] Polymer composition (PC) notably prepared by method Ml can be in the form of a powder of in the form of pellets.

[0122] Thermoplastic composite (TPC)

[0123] The invention also relates to a thermoplastic composite (TPC) comprising:- a matrix comprising at least 40.0 wt% of at least one polyamide (PA) as disclosed herein and optionally at least one plastic additive as disclosed above, this proportion being given relative to the total weight of the TPC;- continuous fibers embedded in the matrix and selected in the group of continuous glass fibers, continuous carbon fibers and combination thereof.

[0124] The thermoplastic composite (TPC) is prepared by a method M2 comprising the steps of impregnating the fibers with a composition in the molten form which forms the matrix and which comprises at least 40.0 wt% of at least one polyamide (PA) asdisclosed herein and optionally at least one plastic additive as disclosed above. Pressure is generally applied on the structure fibers / composition.

[0125] The impregnation may be performed by a slurry process as disclosed notably in US 4,894,105 where the composition is in the form of particles dispersed in an aqueous medium which are brought into contact with the fibers.

[0126] The thermoplastic composite (TPC) may also be used as a hydrogen barrier layer.

[0127] Use of polyamide (PA) or of polymer composition (PC)

[0128] Polyamide (PA) as disclosed herein or the polymer composition (PC) as disclosed herein may be used for the preparation of a hydrogen barrier layer (Lb). For instance, polyamide (PA) may be used as a polyphthalamide in the preparation of a barrier layer as disclosed in US 2019 / 0242525.

[0129] A "hydrogen barrier layer" is a layer which prevents or impedes the transport of hydrogen through itself.

[0130] The hydrogen barrier layer (Lb) may be (i) monolayer or (ii) multilayer wherein at least one layer comprises at least one polyamide (PA) as disclosed herein or the polymer composition (PC) as disclosed herein.

[0131] The hydrogen barrier layer (Lb) is made or comprises at least one polyamide (PA) as disclosed herein or the polymer composition (PC) as disclosed herein.

[0132] Layer (Lb) has a thickness which provides the required value of gas permeation for the application. Layer (Lb) typically has a thickness of at least 100 microns, generally at least 250 microns. Layer (Lb) may have a thickness of up to 10.0 mm, even up to 8.5 mm, even up to 7.5 mm. Layer (Lb) may have a thickness of 100 microns to 10.0 mm, generally from 250 microns to 10.0 mm, even from 300 microns to 8.5 mm, still from 500 microns to 6.0 mm.

[0133] Permeability P

[0134] The hydrogen barrier layer (Lb) of the invention typically exhibits a permeability P of at most 90.0 Ncm3.mm / m2.bar.day, preferably at most 70.0 Ncm3.mm / m2.bar.day, preferably at most 50.0 Ncm3.mm / m2.bar.day, preferably at most 40.0 Ncm3.mm / m2.bar.day.

[0135] The permeability P (or permeation coefficient) of a sample measures its susceptibility to be penetrated and crossed by LU P is obtained by measuring the steady state of transmission using the carrier gas method and a sensor. This method is more precise then the manometric testing method.

[0136] The method of measurement of P is defined in protocol (p2) in the Experimental Section.

[0137] The sample in the form of a circular film is mounted in a cell so as to form a barrier between two chambers. One chamber contains the test gas (EE) and the other chamber is purged with a sweep gas (synthetic air). The feed side is pressurized with EE and during the measurement, the concentration of Eb in the sweep gas flow is measured, typically with an electrochemical Eb sensor. The permeation coefficient (P) is calculated according to the following equation (eq. 1):P = (C.D.d. / A.pP).(T°.p / T.p°) (eq. 1)P = permeation coefficient, typically expressed in Ncm3.mm.d'1.bar1.m'2C = penetrant concentration in ppmD = sweep gas flow rate (typically measured in mL.min'1) d = sample thickness (mm)A = testing area in contact with the gas (m2) pP= penetrant partial pressure (bar) T = ambient temperature (K) p = ambient pressure (bar)T° = standard temperature (273.15 K) p° = standard pressure (1013 bar)

[0138] Further normalization is done to standard temperature and pressure (273.15 K and 1013 bar).

[0139] The film to be tested can notably be prepared according to protocol (pl) in the Experimental Section.

[0140] The conditions provided in the Experimental Section can be followed for the measurement of permeability P.

[0141] Multilayer structure

[0142] The invention also relates to a multilayer structure comprising at least one hydrogen barrier layer (Lb) as disclosed herein, said multilayer structure being intended to store or transport Eb and being selected from a vessel and a pipe.

[0143] The multilayer structure thus comprises from the inside to the outside of the structure:- at least one hydrogen barrier layer (Lb) as disclosed herein;- at least one structural layer (Ls).

[0144] Advantageously, the barrier layer (Lb) or one of the barrier layers (Lb) is in contact or is intended to be in contact with the contained fluid (Eh).

[0145] According to an embodiment, the multilayer structure comprises only one barrier layer (Lb). The multilayer structure may comprise another barrier layer made of or comprising a polymer which is not a polyamide having the composition disclosed in claim 1.

[0146] The function of the structural layer (Ls) is to provide the structural rigidity to the structure and the protection of the hydrogen barrier layer (Lb). The structural layer (Ls) is selected in the group of metallic layers and layers made of a composite material.

[0147] The multilayer structure may comprise two or more reinforcing layers. For instance, the multilayer structure may comprise from the inside to the outside of the structure:- at least one hydrogen barrier layer (Lb) as disclosed herein;- at least one structural layer (Lsi) made of a composite;- at least one metallic structural layer (LS2).

[0148] The composite may be either a thermoset composite or a thermoplastic composite.

[0149] Vessel

[0150] According to an embodiment, the multilayer structure is a vessel.

[0151] The term “vessel” is used herein to refer to a hollow container. The vessel is in particular a hollow container for containing a gas, preferably a pressurized gas.

[0152] The length of the vessel depends on the end use and may for example be between 50.0 cm and up to lengths as large as 10.0 m. These higher lengths are usually employed for gas transport. As an example, for vessels in trucks the length is usually between 1.0 m and 3.0 m.

[0153] The vessel may have an internal volume between 3.5 dm3and 5.0 m3, even from 5.0 dm3and 1.0 m3. The internal volume of the vessel may be at least 10.0 dm3, even at least 15.0 dm3. The internal volume may be up to 1.0 m3, even up to 0.5 m3.

[0154] The vessel typically exhibits a nominal pressure of at least 2.5 MPa, typically at least 20.0 MPa, even at least 30.0 MPa. The nominal pressure may be up to 70.0 MPa, 100 MPa, even 150.00 MPa and more. Advantageously, the vessel has a nominal pressure of 20.0 to 70.0 MPa.

[0155] The vessel typically has a cylindrical shape and a boss is placed at the end. Often, a vessel has two bosses at each end of the cylindrical shape.

[0156] The shape of the hollow body is determined by the desired use. It is usually but not exclusively cylindrical; it typically has a diameter of between 10.0 cm and 1.00 m.

[0157] A further object of the invention is a vessel as disclosed herein and intended to contain H2 or containing H2.

[0158] As a further object of the invention is a vehicle comprising the vessel as disclosed herein. The vehicle may be a car, a truck, a train, a ship, an urban mobility vehicle, an airplane, a helicopter or any other vehicle that could be powered using the conversion of a gas into energy by any means.

[0159] The hydrogen barrier layer (Lb) may be incorporated in a vessel as illustrated in:- US 2019 / 0242525: the vessel may thus notably be a vessel as disclosed in US 2019 / 0242525 comprising a monolayer liner and a reinforcing structure arranged on top of the liner, wherein the liner includes the hydrogen barrier layer (Lb) as disclosed herein; or- US 2010 / 0075200: the vessel may thus notably be a vessel as disclosed in US 2010 / 0075200 comprising: a cap; a liner; and a reinforced layer that is provided on the liner, wherein the liner includes the hydrogen barrier layer (Lb) as disclosed herein; or- US 11,441,732 B2: the vessel may thus notably be a vessel as disclosed in US 11,441,732 B2 including a liner, wherein the liner includes the hydrogen barrier layer (Lb) as disclosed herein.

[0160] Pipe

[0161] According to an embodiment, the multilayer structure is a pipe.

[0162] The pipe is preferably not a three-layer pipe.[EXPERIMENTAL SECTION]

[0163] The present examples illustrate the invention.

[0164] Raw materials used

[0165] The following raw materials were used to prepare the polymer samples: 2- methylpentanediamine (MPMD; from Azelis); 1,9-diaminononane (C9; from Solvay), 1,10-diaminodecane (CIO; from Hangzhou); meta-xylenediamine (MXDA; from Mitsubishi Gas Chemical Company) terephthalic acid (TP A; from Sigma Aldrich), isophthalic acid (IA; from Sigma Aldrich), adipic acid (AA; from Invista), and phosphorus acid (from Sigma Aldrich).

[0166] All of the copolyamides disclosed in Table I were prepared in an autoclave reactor equipped with a distillate line fitted with a pressure control valve. The procedure detailed below for Ex 1 was followed (except for the proportions of the monomers) for the preparation of all copolyamides.

[0167] Example 1

[0168] The polyamide of Exl was prepared by charging into the reactor 2.53 g of MPMD, 2.45 g of CIO, 5.58 g of TP A, 5.21 g of deionized water, and 0.0035 g of phosphorus acid. The reactor was sealed, purged with N2 gas and heated to 145 °C and held for 45 min, followed by heating to 195 °C and holding for 45 min, followed by heating to 230 °C and holding for 35 min, followed by heating to 270 °C and holding for 35 min. The steam generated was slowly released to keep the internal pressure under 200 psig. Once the temperature was at 270 °C for 35 min, the reactor pressure was slowly reduced to atmospheric within 45 min while maintaining 270 °C ± 30 °C. After holding for an additional 30 min with N2 gas purging, the reactor was cooled to RT and the polymer was retrieved from the reactor.

[0169] Thermal Performance

[0170] Tg, Tm and Hm were measured by Differential Scanning Calorimetry (“DSC”) according to ASTM D3418 using a heating and cooling rate of 20 °C / min. Three scans were used for each DSC test: a first heat up to 350 °C, followed by a first cool down to 30 °C, followed by a second heat up to 360 °C. Tg, Tm and Hm were determined from the second heat up. Tc was determined from the first cool down.

[0171] Permeability P

[0172] Preparation of the samples for the measurement of permeability P

[0173] The samples were processed in a micro-compounder / extruder Xplore and injection device (DSM).

[0174] Extruder used: twin screw co rotating extruder

[0175] Useful volume of the extruder: 15 cc

[0176] Temperature setting of the extruder: 275°C

[0177] The extruder was filled with 18 g of the material to be tested (e.g. polyamide) and the screw speed was set at 100 rpm. Once the extruder is filled, the material was kept in the extruder for 3 minutes in recirculating mode at 150 rpm. Then, the melt is transferred in the 12 cc barrel of the injection module, the temperature of the barrel was set at 275°C. The material was injected from the barrel into the mold with a pressure of 8 bars and the pressure was held for 10 seconds. The temperature of the mold was set at 125°C.

[0178] A specific mold cavity was used to prepare square platelets 30x30x1.3 mm from which circular films were obtained.

[0179] Protocol (pl): preparation of the circular filmsparticularly, the following details were followed:- the platelets were placed in a mold. A plastic film is preferably used to avoid sticking between the platelets and the two inner sides of the mold;- the mold was placed on the lower pressure plate;- the temperature of the upper and lower pressure plates was set at 255°C and the force at 15 kN;- the lower plate was raised;- the programmed temperature is held for 5 minutes;- the plates are cooled to 40°C while pressure is maintained;- the lower plate is lowered once the temperature of 40°C is reached.

[0181] Protocol (p2): method of determination of the permeability P

[0182] The calibrated leak detector used was Inficon Sentrac H2.

[0183] The permeation coefficient P was calculated with equation (eq. 1).Table I* proportions of the monomers are given in mol% relative to the diamines in the diamine component(A) and to the diacids in the diacid component (B)** P expressed in Ncm3.mm.m'2.bar1.day1t in the context of the present invention, diacid is equivalent to dicarboxylic acid

[0184] The polyamides of the invention are semi-crystalline and exhibit a higher Tg, a high Tm and a lower Tc. This combination of properties ensure that the polyamides can be processed into a liner having good permeability P.

[0185] The polyamide CE4 has a Tg of only 83°C. The melting temperature Tm of polyamides El and E2 are also higher than the Tm of polyamide CE4.

Claims

CLAIMSClaim 1. Polyamide (PA), the recurring units (RPA) of which are formed from the polycondensation of a diamine component (A) and a dicarboxylic acid component (B), wherein:- the diamine component (A) comprises, consists essentially of or consists of:■ between 50.0 mol% (this value being excluded) and 70.0 mol% of 2- methylpentanediamine (MPMD); and■ between 30.0 and 50.0 mol% of at least one other diamine (DA) of formula 2HN-R1-NH2 where Ri is a Cs-Cn linear or branched alkylene group;■ these proportions in mol% being based on the total amount of diamines in the diamine component (A);■ the expression "consist essentially" meaning that the diamine component (A) consists of MPMD and at least one diamine (DA) with the indicated proportions and up to 1.0 mol%, more preferably up to 0.5 mol%, of one or more diamines other than MPMD and other than diamine (DA), this proportion in mol% being based on the total amount of diamines in the diamine component (A);- the dicarboxylic acid component (B) comprises, consists essentially of or consists of:■ between 90.0 and 100.0 mol.% of terephthalic acid; and■ between 0 and 10.0 mol.% of another diacid (DI) selected in the group consisting of isophthalic acid, adipic acid (AA) and a combination thereof;■ these proportions in mol% being based on the total amount of diacids in the dicarboxylic acid component (B);■ the expression "consist essentially" meaning that the dicarboxylic acid component (B) consists of terephthalic acid and optionally of the other diacid (DI) with the indicated proportions and a combination thereof and up to 1.0 mol%, more preferably up to 0.5 mol%, of one or more dicarboxylic acids other than terephthalic acid and other than diacid (DI), this proportion in mol% being based on the total amount of di carboxylic acids in the dicarboxylic acid component (B);- wherein the proportion of MPMD. T recurring units in the polyamide (PA) are greater than 50.0 mol% (> 50.0 mol%), this proportion being given relative to the total number of moles of recurring units in the polyamide (PA).Claim 2. Polyamide (PA) according to claim 1, wherein:- the diamine component (A) consists essentially of or consists of:■ between 50.0 mol% (this value being excluded) and 70.0 mol% of 2- methylpentanediamine (MPMD); and■ between 30.0 and 50.0 mol% of at least one other diamine (DA) of formula 2HN-R1-NH2 where Ri is a Cs-Cn linear or branched alkylene group;■ these proportions in mol% being based on the total amount of diamines in the diamine component (A);■ the expression "consist essentially" meaning that the diamine component (A) consists of MPMD and at least one diamine (DA) with the indicated proportions and up to 1.0 mol%, more preferably up to 0.5 mol%, of one or more diamines other than MPMD and other than diamine (DA), this proportion in mol% being based on the total amount of diamines in the diamine component (A); and / or- the dicarboxylic acid component (B) consists essentially of or consists of:■ between 90.0 and 100.0 mol.% of terephthalic acid; and■ between 0 and 10.0 mol.% of another diacid (DI) selected in the group consisting of isophthalic acid, adipic acid (AA) and a combination thereof;■ these proportions in mol% being based on the total amount of diacids in the dicarboxylic acid component (B);■ the expression "consist essentially" meaning that the dicarboxylic acid component (B) consists of terephthalic acid and optionally of the other diacid (DI) with the indicated proportions and a combination thereof and up to 1.0 mol%, more preferably up to 0.5 mol%, of one or more dicarboxylic acids other than terephthalic acid and other than diacid (DI), this proportion in mol% being based on the total amount of di carboxylic acids in the dicarboxylic acid component (B).Claim 3. Polyamide (PA) according to claim 1 or 2, wherein the proportion of MPMD and the total proportion of diamine(s) (DA) in the diamine component (A) are respectively between 53.0 and 63.0 mol% and 37.0 and 47.0 mol%.Claim 4. Polyamide (PA) according to any one of the preceding claims, wherein the proportion of terephthalic acid and the total proportion of diacid(s) (DI) in the dicarboxylic acid component (B) are respectively between 95.0 and 100.0 mol% and between 0 and 5.0 mol%; preferably respectively between 97.0 and 100.0 mol% and between 0 and 3.0 mol%; preferably respectively between 99.0 and 100.0 mol% and between 0 and 1.0 mol%.Claim 5. Polyamide (PA) of any one of the preceding claims, wherein the diacid component (B) consists essentially of or consists of terephthalic acid.Claim 6. Polyamide (PA) according to any one of the preceding claims, wherein the recurring units (RPA) of polyamide (PA) consist essentially or consist of the following units (RPAI)- (RPA4):the expression "consist essentially" meaning that the recurring units of polyamide (PA) consist of recurring units (RPAI)-(RPA4) and up to 1.0 mol%, more preferably up to 0.50 mol%, more preferably up to 0.25 mol%, more preferably up to 0.10 mol%, of recurring units other than said recurring units (RPAI)-(RPA4), this proportion in mol% being based on the total amount of recurring units in the polyamide (PA).Claim 7. Polyamide (PA), notably according to any one of the preceding claims, the recurring units of which consist essentially of or consist of recurring units (RPAI) and (RPA2):where Ri is a Cs-Cn linear or branched alkylene group derived from at least one diamine (DA) of formula 2HN-R1-NH2, wherein the proportions of units (RPAI) and (RPA2) relative to the total number of recurring units in the polyamide (PA) are the following:- (RPAI): 50.0 mol% (this value being excluded) and 70.0 mol%;- (RPA2): between 30.0 and 50.0 mol%; or the following ones- (RPAI): 53.0 and 63.0 mol%;- (RPA2): between 37.0 and 47.0 mol%.Claim 8. Polyamide (PA) according to any one of the preceding claims, wherein the diamine (DA) is selected in the group consisting of:1,8-octanediamine, 1,9-diaminononane, 1,10-diaminodecane and 2-methyl-l,8- octanediamine and combination of two or more of these diamines; or- 1,8-octanediamine, 1,9-diaminononane, 1,10-diaminodecane and combination of two or more of these diamines; or- 1,8-octanediamine, 1,9-diaminononane, 1,10-diaminodecane and combination of 1,9- diaminononane and 1,10-diaminodecane.Claim 9. Polyamide (PA) according to any one of the preceding claim, which is (i) free of or (ii) does not comprise units derived from:- 1,6-hexamethylene diamine; and / or- 2-methyl-l,8-octanediamine; and / or- m-xylylenediamine or p-xylylenediamine; and / or- l,3-bis(aminomethyl)cyclohexane or l,4-bis(aminomethyl)cyclohexane; and / or- a lactam or an amino-acid; the expression “free of” in relation to specific recurring units meaning that the proportion of said recurring units in the polyamide (PA) is lower than or equal to 1.0 mol%, preferably lower than or equal to 0.50 mol%, preferably lower than or equal to 0.25 mol%, preferably lower than or equal to 0.10 mol%.Claim 10. Polyamide (PA) according to any one of the preceding claims, wherein the end- groups of the polyamide (PA) are selected in the group of -NH2, -COOH and amide end- groups.Claim 11. Polyamide (PA) selected in the group of MPMD.T / 10. T and MPMD.T / 9.T copolyamides.Claim 12. Polyamide (PA) according to any one of the preceding claims, exhibiting an inherent viscosity (IV) of at least 0.9 dL / g, preferably between 0.9 and 1.3 dL / g, the IV being measured according to ASTM D5336 - 22 with the use of a mixture phenol / 1, 1, 2, 2-tri chloroethane (60 / 40 wt ratio).Claim 13. Polyamide (PA) according to any one of the preceding claims, exhibiting a glass transition temperature (Tg) of at least 115°C, preferably at least 120°C, preferably at least 125°C, preferably strictly higher than 125°C (> 125°C), Tg being measured by Differential Scanning Calorimetry (“DSC”) according to ASTM D3418, notably using a heating and cooling rate of 20°C / min.Claim 14. Polyamide (PA) according to any one of the preceding claims, exhibiting a melting temperature (Tm) which is:- at most 270 °C, preferably at most 250 °C, preferably at most 245°C; and / or- at least 230°C;Tm being measured by Differential Scanning Calorimetry (“DSC”) according to ASTM D3418, notably using a heating and cooling rate of 20°C / min; and / orClaim 15. Polyamide (PA) according to any one of the preceding claims, exhibiting a crystallization temperature (Tc) at most 200 °C, preferably at most 190 °C, Tc being measured by Differential Scanning Calorimetry (“DSC”) according to ASTMD3418, using a heating and cooling rate of 20°C / min, Tc being measured from the first cool down.Claim 16. Polyamide (PA) according to any one of the preceding claims, wherein the polyamide (PA) is semi -crystalline.Claim 17. Polyamide (PA) according to any one of the preceding claims, exhibiting a heat of fusion (Hm) of at least 20.0 J / g, preferably at least 25.0 J / g, Hm being measured by Differential Scanning Calorimetry (“DSC”) according to ASTM D3418, notably using a heating and cooling rate of 20°C / min.Claim 18. Polyamide (PA) according to any one of the preceding claims, prepared by polycondensation by heating a reaction mixture (RM) comprising the monomers, preferably in the presence of less than 60 wt.% of water, preferentially less than 30 wt.%, preferably less than 20 wt.%, preferably less than 10 wt.%, this proportion being based on the total weight of the reaction mixture, preferentially with no added water.Claim 19. Polyamide (PA) according to any one of the preceding claims, prepared by polycondensation by heating a reaction mixture (RM) comprising, consisting essentially of or consisting of:- a mixture of monomers (MM) comprising, consisting essentially of or consisting of the diamine component (A) and the dicarboxylic acid component (B);- optionally a catalyst, notably selected in the group consisting of phosphorous acid, ortho-phosphoric acid, meta-phosphoric acid, alkali-metal hypophosphite such as sodium hypophosphite and phenylphosphinic acid;- optionally at least one capping agent, notably selected in the group of monocarboxylic acids of formula R-COOH, primary amines of formula R-NH2 where R is an alkyl group, an aryl group or a cycloalkyl group and R' is a linear or branched C2-C18 alkyl group;- optionally water in a proportion which is preferably less than 80.0 wt.%, preferably less than 50.0 wt.% water, this proportion of water being based on the total weight of the reaction mixture (RM).Claim 20. Polyamide (PA) according to claim 18 or 20, wherein the reaction mixture (RM) contains a mixture of monomers (MM) comprising all diamines and all dicarboxylic acids as monomers of the polyamide (PA), the monomer mixture (MM) being preferably free of any lactam or any aminoacid, the expression “free of” meaning that the total proportion of lactam(s) and the total proportion of aminoacid(s) are each lower than or equal to 1.0 wt% (< 1.0 wt%), these proportions being expressed relative to the total weight of mixture (MM).Claim 21. Process of preparation of a polyamide (PA) as disclosed in any one of claims 1-20, by polycondensation, the process comprising a step of heating a reaction mixture (RM) comprising the monomers, preferably in the presence of less than 60 wt.% of water, preferentially less than 30 wt.%, preferably less than 20 wt.%, preferably less than 10 wt.%, this proportion being based on the total weight of the reaction mixture, preferentially with no added water.Claim 22. Process of preparation of a polyamide (PA) as disclosed in any one of claims 1-20, by polycondensation, the process comprising a step of heating a reaction mixture (RM) comprising, consisting essentially of or consisting of:- a mixture of monomers (MM) comprising, consisting essentially of or consisting of the diamine component (A) and the dicarboxylic acid component (B);- optionally a catalyst, notably selected in the group consisting of phosphorous acid, ortho-phosphoric acid, meta-phosphoric acid, alkali-metal hypophosphite such as sodium hypophosphite and phenylphosphinic acid;- optionally at least one capping agent, notably selected in the group of monocarboxylic acids of formula R-COOH, primary amines of formula R'-NH2 where R is an alkyl group, an aryl group or a cycloalkyl group and R' is a linear or branched C2-C18 alkyl group;- optionally water in a proportion which is preferably less than 80.0 wt.%, preferably less than 50.0 wt.% water, this proportion of water being based on the total weight of the reaction mixture (RM).Claim 23. Polymer composition (PC) comprising at least 50.0 wt% of at least one polyamide (PA) according to any one of claims 1-20 and optionally at most 20.0 wt% of at least one inorganic filler and / or at least one plastic additive other than inorganic filler, this proportion being based on the total weight of the polymer composition (PC), the components of polymer composition (PC) being preferably blended together.Claim 24. Polymer composition (PC) according to claim 23, wherein the inorganic filler is selected in the group consisting of talc, clay, mica, kaolin, calcium carbonate, calcium silicate, magnesium carbonate, glass fibers, carbon fibers and combinations thereof.Claim 25. Polymer composition (PC) according to claim 23, wherein the inorganic filler is a clay, notably selected in the group consisting of montmorillonite, hectorite, saponite, vermiculite and combination of two or more of said clays.Claim 26. Polymer composition (PC) according to any one of claims 23-25, wherein the plastic additive is selected in the group consisting of tougheners, plasticizers, colorants, pigments, antistatic agents, dyes, lubricants, thermal stabilizers, light stabilizers, flame retardants, nucleating agents, antioxidants, UV absorbers, acid scavengers and combinations thereof.Claim 27. Polymer composition (PC) according to any one of claims 23-25 in the form of a powder of in the form of pellets.Claim 28. Use of a polyamide (PA) according to any one of claims 1-20 or the polymer composition (PC) according to any one of claims 22-27, for the preparation of a hydrogen barrier layer (Lb) or for the preparation of a vessel or a pipe intended to contain H2 or containing H2.Claim 29. Use according to claim 28, wherein the hydrogen barrier layer (Lb) is (i) monolayer or (ii) multilayer wherein at least one layer comprises the polyamide (PA) or the polymer composition (PC).Claim 30. Hydrogen barrier layer (Lb) made of or comprising at least one polyamide (PA) as disclosed in any one of claims 1-20 or a polymer composition as disclosed in any one of claims 23-27.Claim 31. Hydrogen barrier layer (Lb) according to claim 30, exhibiting a permeability P of at most 90 Ncm3.mm / m2.bar.day, preferably at most 70.0 Ncm3.mm / m2.bar.day, preferably at most 50.0 Ncm3.mm / m2.bar.day, preferably at most 40.0 Ncm3.mm / m2.bar.day, the conditions of measurement of the permeability P being defined in protocol (p2) in the Experimental Section or in the Experimental Section.Claim 32. Hydrogen barrier layer (Lb) according to claim 30 or 31, having a thickness of 100 pm to 10.0 mm.Claim 33. Multilayer structure intended to store or transport H2 and selected from a vessel and a pipe, comprising at least one hydrogen barrier layer (Lb) as disclosed in any one of claims 30-32.Claim 34. Multilayer structure intended to store or transport H2 and selected from a vessel and a pipe, comprising from the inside to the outside of the structure:- at least one hydrogen barrier layer (Lb) as disclosed in any one of claims 30-32;- at least one structural layer (Ls).Claim 35. Multilayer structure according to claim 33 or 34, wherein the barrier layer (Lb) or one of the barrier layer (Lb) is in contact or is intended to be in contact with the contained fluid (H2).Claim 36. Multilayer structure according to any one of claims 33-35, wherein the multilayer structure comprises only one barrier layer (Lb), being understood that the multilayer structure may comprise another barrier layer made of or comprising a polymer which is not a polyamide having the composition disclosed in claim 1.Claim 37. Vessel or pipe having a multilayer structure as disclosed in any one of claims 33-36 and intended to contain H2 or containing H2.Claim 38. Thermoplastic composite (TPC) comprising:- a matrix comprising at least 40.0 wt% of at least one polyamide (PA) as disclosed in any one of claims 1-20 and optionally at least one plastic additive, notably selected in the group consisting of tougheners, plasticizers, colorants, pigments, antistatic agents, dyes, lubricants, thermal stabilizers, light stabilizers, flame retardants, nucleating agents, antioxidants, UV absorbers, acid scavengers and combinations thereof, this proportion being given relative to the total weight of the TPC;- continuous fibers embedded in the matrix and selected in the group of continuous glass fibers, continuous carbon fibers and combination thereof.

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