Tubular structure having low ion conductivity

Abstract

The present invention relates to a single-layer or multi-layer tubular structure for transporting a coolant, comprising at least one inner layer (I) containing at least one thermoplastic polymer selected from polyolefins, thermoplastic vulcanizates (TPV), fluoropolymers, polyphenylene sulfide (PPS), and polyphthalamide (PPA), the tube being intended for fuel cell cooling, and the aforementioned coolant having a dielectric conductivity of less than 30 μS / cm as determined after aging the aforementioned single-layer or multi-layer tubular structure at 80 °C for 168 hours in contact with the aforementioned coolant.

Description

Technical Field

[0001] The present invention relates to a single-layer or multi-layer tubular structure for transporting a coolant, and the aforementioned tube is for fuel cell cooling purposes.

Background Art

[0002] A fuel cell is an electrochemical power generation device that enables the direct conversion of the chemical energy of a fuel (e.g., hydrogen) into electrical energy. The thermal control of this fuel cell is important for ensuring good yield and good service life. Heat exchange via a fluid remains the most efficient and most economical system.

[0003] The heat transfer fluid circulates inside the battery. Therefore, the fluid must be a dielectric so as not to interfere with or, worse still, degrade the performance of the fuel cell. The fluid should also not contain chemical elements (oligomers, additives) that could contaminate the battery.

[0004] The tubular structure for transporting the coolant of a fuel cell must not change the dielectric conductivity of the aforementioned coolant, especially. It must not release oligomers and / or ions into the aforementioned coolant and must have very good resistance to contact with the heat transfer fluid.

[0005] U.S. Patent Application Publication No. 2019 / 0285203 describes a tubular structure having five layers, especially HDPE / binder / PA6 / binder / HDPE, as a cooling tube for automobiles.

[0006] International Publication No. 2020 / 039356 describes a line having at least three layers of TPV / PP / TPV (TPV: thermoplastic vulcanizate) for automobiles, especially an automobile temperature control line for fluid temperature control and a cooling medium.

[0007] U.S. Patent Application Publication No. 2007 / 148388 describes an engine coolant line that includes at least two layers: an outer layer made of a polyamide composition and an inner layer made of a polypropylene composition containing at least 50 wt% polypropylene, where the polypropylene is a heterophasic copolymer of propene and ethene.

[0008] European Patent Application Publication No. 3670172 describes a multilayer pipe that includes at least one inner layer made of polypropylene (PP) and at least one outer layer made of polyphthalamide (PPA).

[0009] However, neither the use of these pipes for fuel cell cooling, nor the mode of dielectric conduction of the coolant transported by these pipes, nor the release of oligomers and / or ions are disclosed by these pipes.

[0010] Therefore, there is a need to provide a pipe that can be used for fuel cell cooling, can transport a coolant having a dielectric conductivity, and does not release oligomers and / or ions into the aforementioned coolant.

Summary of the Invention

[0011] Accordingly, the present invention relates to a single-layer or multilayer tubular structure for transporting a coolant, including at least one inner layer (I) containing at least one thermoplastic polymer selected from polyolefins, thermoplastic vulcanizates (TPV), fluoropolymers, polyphenylene sulfide (PPS), and polyphthalamide (PPA), wherein the aforementioned tubular structure is for the purpose of fuel cell cooling, and the aforementioned coolant has a dielectric conductivity of less than 30 μS / cm determined after aging the aforementioned single-layer or multilayer tubular structure in contact with the aforementioned coolant at 80 °C for 168 hours.

[0012] Accordingly, the inventors have unexpectedly found that a single-layer or multilayer tubular structure for transporting a coolant, comprising at least one inner layer (I) having a dielectric conductivity of less than 30 μS / cm and comprising at least one thermoplastic polymer as defined above, enables fuel cell cooling while avoiding the release of oligomers and / or ions into the aforementioned coolant.

[0013] Throughout the specification, the expression "tubular structure" and the terms "tube" or "pipe" have the same meaning and can be used interchangeably.

[0014] The aforementioned coolant is any heat transfer liquid, especially a coolant based on water and additives.

[0015] It is based on water containing glycols, especially propylene glycol or ethylene glycol.

[0016] The electrical conductivity or dielectric conductivity, expressed in microsiemens per centimeter (μS / cm), characterizes the ability of a material or solution to move charges freely and thus allow the passage of an electric current. This is measured on the coolant at ambient temperature with magnetic stirring after aging the aforementioned single-layer or multilayer tubular structure in contact with the aforementioned coolant at 80 °C for 168 hours using a calibrated conductivity meter with automatic temperature compensation (HORIBA LAQUA-EC220K model equipped with a HORIBA 3552 3G0E0042 probe).

[0017] Regarding the thermoplastic polymer of the inner layer (I) It is selected from polyolefins, thermoplastic vulcanizates (TPV), fluoropolymers, polyphenylene sulfide (PPS) and polyphthalamide (PPA).

[0018] According to the present invention, the inner layer (I) consists essentially of a polyolefin, a thermoplastic vulcanizate (TPV), a fluoropolymer, polyphenylene sulfide (PPS) or polyphthalamide (PPA). The inner layer (I) may also contain, inter alia, additives or conventional additives in addition to the aforementioned thermoplastic materials.

[0019] Among the additives, those selected, inter alia, from catalysts, antioxidants, heat stabilizers, UV stabilizers, light stabilizers, lubricants, fillers, plasticizers, flame retardants, nucleating agents, dyes, conductive agents, heat conductors, impact resistance improvers or mixtures thereof may be mentioned.

[0020] The inner layer is suitably composed of at least 90% by weight, preferably at least 92% by weight, more preferably at least 95% by weight and very preferably at least 98% by weight of a polyolefin, a thermoplastic vulcanizate (TPV), a fluoropolymer, polyphenylene sulfide (PPS) or polyphthalamide (PPA).

[0021] Polyolefin In one embodiment, the thermoplastic polymer of the inner layer (I) is a polyolefin selected from non-functionalized polyolefins, functionalized polyolefins and mixtures of the two.

[0022] For the sake of simplicity, the polyolefin is denoted by (B), and the functionalized polyolefin (B1) and the non-functionalized polyolefin (B2) are described below.

[0023] The non-functionalized polyolefin (B2) is conventionally a homopolymer or copolymer of an α-olefin or diolefin, for example ethylene, propylene, 1-butene, 1-octene or butadiene. By way of example, - Polyethylene homopolymers and copolymers, in particular LDPE, HDPE, LLDPE (linear low density polyethylene), VLDPE (very low density polyethylene) and metallocene polyethylene, - Propylene homopolymers or copolymers, - Ethylene / α-olefin, for example ethylene / propylene, copolymer, EPR (abbreviation for ethylene propylene rubber) and ethylene / propylene / diene (EPDM), - A copolymer of ethylene and at least one product selected from salts or esters of unsaturated carboxylic acids such as alkyl (meth)acrylates (for example methyl acrylate), or vinyl esters of saturated carboxylic acids such as vinyl acetate (EVA), wherein the proportion of comonomer can be up to 40% by weight can be mentioned.

[0024] The functionalized polyolefin (B1) may be a polymer of an α-olefin having a reactive unit (functional group). Such reactive units are acid, anhydride or epoxy functional groups. As examples, unsaturated epoxides such as glycidyl (meth)acrylate, or carboxylic acids or corresponding salts or esters such as (meth)acrylic acid (the latter can be completely or partially neutralized with a metal such as Zn), or carboxylic acid anhydrides such as maleic anhydride grafted or copolymerized or terpolymerized with the aforementioned polyolefin (B2) can be mentioned. The functionalized polyolefin is, for example, a PE / EPR mixture, and its weight ratio can vary within a wide range, for example between 40 / 60 and 90 / 10, and the aforementioned mixture is co-grafted with an anhydride, especially maleic anhydride, at a grafting degree of, for example, 0.01% to 5% by weight.

[0025] The functionalized polyolefin (B1) is the following (co)polymer grafted with maleic anhydride or glycidyl methacrylate (the grafting degree is, for example, 0.01% to 5% by weight): - PE, PP, copolymers of ethylene and propylene, butene, hexene or octene, for example copolymers containing 35% to 80% by weight of ethylene; - Ethylene / α-olefin, for example ethylene / propylene, copolymer, EPR (abbreviation for ethylene propylene rubber) and ethylene / propylene / diene (EPDM); - Styrene / ethylene-butene / styrene (SEBS), styrene / butadiene / styrene (SBS), styrene / isoprene / styrene (SIS) and styrene / ethylene-propylene / styrene (SEPS) block copolymers; - Copolymers of ethylene and vinyl acetate (EVA) containing up to 40% by weight of vinyl acetate; - Copolymers of ethylene and alkyl (meth)acrylate containing up to 40% by weight of alkyl (meth)acrylate; - Copolymers of ethylene, vinyl acetate (EVA) and alkyl (meth)acrylate, containing up to 40% by weight of comonomers can be selected from.

[0026] The functionalized polyolefin (B1) may also be selected from ethylene / propylene copolymers (products described in European Patent Application Publication No. 0342066) which are preponderant in propylene, grafted with maleic anhydride and then condensed with monoaminated polyamide (or monoaminated polyamide oligomer).

[0027] The functionalized polyolefin (B1) may also be a copolymer or terpolymer of at least the following units: (1) ethylene, (2) alkyl (meth)acrylate or vinyl ester of saturated carboxylic acid and (3) anhydride such as maleic anhydride, or (meth)acrylic acid, or epoxy such as glycidyl (meth)acrylate.

[0028] Examples of the latter type of functionalized polyolefin are the following copolymers: - Ethylene / alkyl (meth)acrylate / (meth)acrylic acid or maleic anhydride or glycidyl methacrylate copolymer; - Ethylene / vinyl acetate / maleic anhydride or glycidyl methacrylate copolymer; - Ethylene / vinyl acetate or alkyl (meth)acrylate / (meth)acrylic acid or maleic anhydride or glycidyl methacrylate copolymer can be mentioned, where ethylene preferably represents at least 60% by weight, and the termonomer (functional group) represents, for example, a copolymer of 0.1% to 10% by weight.

[0029] In the above-mentioned copolymer, (meth)acrylic acid can be saltified with Zn or Li.

[0030] The term "alkyl (meth)acrylate" in (B1) or (B2) refers to C1-C8 alkyl methacrylate and acrylate, and can be selected from methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, methyl methacrylate and ethyl methacrylate.

[0031] Furthermore, the above-mentioned polyolefin (B1) may also be crosslinked via any suitable process or reagent (diepoxy, diacid, peroxide, etc.). The term "functionalized polyolefin" also includes a mixture of the above-mentioned polyolefin and a bifunctional reagent such as a diacid, dianhydride, diepoxy that can react with these polyolefins, or a mixture of at least two functionalized polyolefins that can react with each other.

[0032] The above-mentioned copolymers (B1) and (B2) may be copolymerized randomly or in block form, and may have a linear or branched structure.

[0033] The molecular weight, MFI index and density of these polyolefins can also vary within a wide range as understood by those skilled in the art. MFI is the abbreviation of Melt Flow Index. This is measured according to the standard ASTM 1238.

[0034] Advantageously, the non-functionalized polyolefin (B2) is selected from polypropylene homopolymers or copolymers, and any ethylene homopolymer or copolymer of ethylene and higher alpha-olefin type comonomers such as butene, hexene, octene, or 4-methyl-1-pentene. Examples include PP, high density PE, medium density PE, linear low density PE, low density PE, or ultra-low density PE. These polyethylenes are known to those skilled in the art as being produced according to "radical" processes, according to "Ziegler" type catalysis, or more recently according to "metallocene" catalysis.

[0035] Advantageously, the functionalized polyolefin (B1) is selected from any polymer containing alpha-olefin units and units having polar reactive functional groups such as epoxy, carboxylic acid, or carboxylic acid anhydride functional groups. Examples of such polymers include terpolymers of ethylene, alkyl acrylate, and maleic anhydride or glycidyl methacrylate, such as Lotader® products (SK Functional Polymer), or polyolefins grafted with maleic anhydride, such as Orevac® products (SK Functional Polymer), and terpolymers of ethylene, alkyl acrylate, and (meth)acrylic acid. Also included are polypropylene homopolymers or copolymers grafted with carboxylic acid anhydride and then condensed with monoaminated polyamide or monoaminated polyamide oligomers.

[0036] In one embodiment, the polyolefin is non-functionalized.

[0037] Advantageously, the non-functionalized polyolefin is selected from polyethylene and polypropylene, particularly polyethylene, particularly high density polyethylene (HDPE).

[0038] Thermoplastic vulcanizate In another embodiment, the thermoplastic polymer of the inner layer (I) is a thermoplastic vulcanizate (TPV).

[0039] A thermoplastic vulcanizate (TPV) is a mechanical mixture of an olefinic thermoplastic polymer and a polyethylene or polypropylene matrix, especially a polypropylene matrix, and a vulcanized elastomer such as a vulcanized PP / EPDM (ethylene propylene diene monomer) mixture.

[0040] Fluoropolymer In one embodiment, the aforementioned thermoplastic polymer of the inner layer (I) is a fluoropolymer.

[0041] A fluoropolymer is a polymer having fluorocarbons as repeating units.

[0042] It can consist of the following monomers: ethylene (E), propylene (P), vinyl fluoride (VF1), vinylidene fluoride (VDF or VF2), tetrafluoroethylene (TFE), hexafluoropropylene (HFP), perfluoropropyl vinyl ether (PPVE), perfluoromethyl vinyl ether (PMVE) and chlorotrifluoroethylene (CTFE): CFCl=CF2.

[0043] In particular, the fluoropolymer is selected from poly(vinylidene fluoride) (PVDF), polytetrafluoroethylene (PTFE), polychlorotrifluoroethylene (PCTFE), ethylene tetrafluoroethylene (ETFE), a terpolymer of tetrafluoroethylene, ethylene and hexafluoropropylene (EFEP), a copolymer of tetrafluoroethylene and a perfluoroalkyl vinyl ether, and mixtures thereof, especially ethylene tetrafluoroethylene (ETFE).

[0044] Polyphenylene sulfide (PPS) In one embodiment, the aforementioned thermoplastic polymer of the inner layer (I) is polyphenylene sulfide (PPS).

[0045] Polyphenylene sulfide (PPS) is a thermally stable semi-crystalline polymer.

[0046] Polyphthalamide (PPA) In one embodiment, the aforementioned thermoplastic polymer of the inner layer (I) is polyphthalamide (PPA).

[0047] The nomenclature used to define polyamides is described in ISO 1874-1:2011 "Plastics - Polyamide (PA) moulding and extrusion materials - Part 1: Designation system", in particular on page 3 (Tables 1 and 2), and is well known to those skilled in the art.

[0048] Polyphthalamide may be a homopolyamide or a copolyamide.

[0049] In the form of a homopolyamide, it is of the formula XAr or MXDY.

[0050] XAr represents units obtained from the polycondensation of diamine X and aromatic dicarboxylic acid, and diamine X is C6 - C36, preferably C6 - C18, preferably C6 - C12, more preferably C10 - C12.

[0051] The diamine may be linear or branched. Advantageously, it is linear.

[0052] At least one of the aforementioned C6 - C36 diamines X may be selected in particular from 1,6 - hexamethylenediamine, 1,7 - heptamethylenediamine, 1,8 - octamethylenediamine, 1,9 - nonamethylenediamine, 1,10 - decamethylenediamine, 1,11 - undecamethylenediamine, 1,12 - dodecamethylenediamine, 1,13 - tridecamethylenediamine, 1,14 - tetradecamethylenediamine, 1,16 - hexadecamethylenediamine and 1,18 - octadecamethylenediamine, octadecenediamine, eicosanediamine, docosanediamine and diamines obtained from fatty acids.

[0053] Advantageously, at least one of the aforementioned diamines X has 6 to 18 carbon atoms and is selected from 1,6-hexamethylenediamine, 1,7-heptamethylenediamine, 1,8-octamethylenediamine, 1,9-nonamethylenediamine, 1,10-decamethylenediamine, 1,11-undecamethylenediamine, 1,12-dodecamethylenediamine, 1,13-tridecamethylenediamine, 1,14-tetradecamethylenediamine, 1,16-hexadecamethylenediamine, and 1,18-octadecamethylenediamine.

[0054] Advantageously, at least one of the aforementioned C6-C12 diamines X is particularly selected from 1,6-hexamethylenediamine, 1,7-heptamethylenediamine, 1,8-octamethylenediamine, 1,9-nonamethylenediamine, 1,10-decamethylenediamine, 1,11-undecamethylenediamine, and 1,12-dodecamethylenediamine.

[0055] Advantageously, at least one of the aforementioned C6-C12 diamines X is particularly selected from 1,6-hexamethylenediamine, 1,7-heptamethylenediamine, 1,8-octamethylenediamine, 1,9-nonamethylenediamine, 1,10-decamethylenediamine, 1,11-undecamethylenediamine, and 1,12-dodecamethylenediamine.

[0056] Advantageously, the diamine X used is a C10-C12 diamine particularly selected from 1,10-decamethylenediamine, 1,11-undecamethylenediamine, and 1,12-dodecamethylenediamine.

[0057] The aromatic dicarboxylic acid is advantageously selected from terephthalic acid (denoted as T), isophthalic acid (denoted as I), and 2,6-naphthalenedicarboxylic acid (denoted as N) or a mixture thereof. In particular, it is selected from terephthalic acid (denoted as T), isophthalic acid (denoted as I), or a mixture thereof.

[0058] MXDY represents units obtained from the polycondensation of meta-xylylenediamine (MXD) and at least one aliphatic dicarboxylic acid Y.

[0059] The aforementioned at least one C6-C36 dicarboxylic acid Y can be selected from adipic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, brassilic acid, tetradecanedioic acid, pentadecanedioic acid, hexadecanedioic acid, octadecanedioic acid, and diacids obtained from fatty acids.

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

[0061] Advantageously, the aforementioned at least one dicarboxylic acid Y is a C6-C18 dicarboxylic acid and is selected from adipic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, brassilic acid, tetradecanedioic acid, pentadecanedioic acid, hexadecanedioic acid, and octadecanedioic acid.

[0062] Advantageously, the aforementioned at least one dicarboxylic acid Y is a C6-C12 dicarboxylic acid and is selected from adipic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, and dodecanedioic acid.

[0063] [[ID=2@]]Advantageously, the aforementioned at least one dicarboxylic acid Y is a C10-C12 dicarboxylic acid and is selected from sebacic acid, undecanedioic acid, and dodecanedioic acid.

[0064] Therefore, when the aforementioned semi-crystalline aliphatic polyamide is obtained from the polycondensation of at least one diamine X and at least one dicarboxylic acid Y, it may contain a single diamine or several diamines and a single dicarboxylic acid or several dicarboxylic acids.

[0065] Advantageously, the aforementioned semi-crystalline aliphatic polyamide is obtained from the polycondensation of a single diamine X and a single dicarboxylic acid Y.

[0066] In particular, the polyphthalamide (PPA) is selected from PA5T, PA6T, PA9T, PA10T, PA11T, PA12T, MXD6, MXD10 and MXD12.

[0067] Throughout the specification, it should be noted that the C9 diamine contains diamine units containing 1,9-nonanediamine units and / or 2-methyl-1,8-octanediamine units in an amount of 60 mol% or more with respect to all C9 diamine units.

[0068] When it is in the form of a copolyamide, it has the formula: PA11 / 10T, PA12 / 10T, PA11 / 12T, PA12 / 12T, PA610 / 10T, PA612 / 10T, PA1010 / 10T, PA1012 / 10T, PA1212 / 10T, PA610 / 12T, PA612 / 12T, PA1010 / 12T, PA1012 / 12T and PA1212 / 12T, in particular those of PA11 / 10T and PA11 / 12T.

[0069] It is in particular a semi-aromatic polyamide of the formula X / YAr as described in European Patent No. 1505099, especially of the formula A / XT, wherein A is selected from units obtained from amino acids, units obtained from lactams and units corresponding to the formula (Ca diamine).(Cb diacid), a represents the number of carbon atoms of the diamine, b represents the number of carbon atoms of the diacid, a and b are each from 4 to 36, preferably from 9 to 18, the (Ca diamine) units are selected from linear or branched aliphatic diamines, cycloaliphatic diamines and alkylaromatic diamines, and the (Cb diacid) units are selected from linear or branched aliphatic diacids, cycloaliphatic diacids and aromatic diacids. XT represents units resulting from the polycondensation of Cx diamines and terephthalic acid, x representing the number of carbon atoms in the Cx diamine, x being 6 to 36, advantageously 9 to 18, especially polyamides of the formula A / 5T, A / 6T, A / 9T, A / 10T, A / 11T or A / 12T, where A is as defined above, in particular PA 5T / 10T, PA11 / 10T, PA MPMDT / 6T, PA MXDT / 6T, PA MXDT / 10T, PA MPMDT / 10T, PA BACT / 6T, PA BACT / 10T, PA 11 / BACT, PA 11 / 6T / 10T, PA BACT / 10T / 6T, PA 11 / BACT / 6T, PA 11 / MPMDT / 6T, PA 11 / MPMDT / 10T, PA 11 / BACT / 10T, PA The polyamide is selected from 11 / MXDT / 6T, PA 11 / MXDT / 10T and 11 / 5T / 10T.

[0070] T corresponds to terephthalic acid, MXD corresponds to m-xylylenediamine, MPMD corresponds to methylpentamethylenediamine, and BAC corresponds to bis(aminomethyl)cyclohexane.

[0071] In particular, the said thermoplastic polymer of the inner layer (I) is a polyphthalamide (PPA) selected from PA9T, PA6T, PA11 / 10T, PA12 / 10T, PA11 / 12T, PA 12 / 12T, PA610 / 10T, PA612 / 10T, PA1010 / 10T, PA1012 / 10T, PA1212 / 10T, PA610 / 12T, PA612 / 12T, PA1010 / 12T, PA 1012 / 12T and PA1212 / 12T, in particular PA11 / 10T and PA11 / 12T.

[0072] About the structure itself The tubular structures of the present invention may be single or multi-layered and are used to transport coolant, such tubes being intended for fuel cell cooling.

[0073] Whether single-layer or multi-layer, it includes at least one layer (I) containing at least one thermoplastic polymer selected from polyolefin, thermoplastic vulcanizate (TPV), fluoropolymer, polyphenylene sulfide (PPS), and polyphthalamide (PPA). The aforementioned coolant has a dielectric conductivity of less than 30 μS / cm as determined after aging the aforementioned single-layer or multi-layer tubular structure at 80 °C for 168 hours in contact with the aforementioned coolant.

[0074] In one embodiment, it includes at least one layer (I) containing at least one thermoplastic polymer selected from non-functionalized polyolefin, thermoplastic vulcanizate (TPV), fluoropolymer, polyphenylene sulfide (PPS), and polyphthalamide (PPA). The aforementioned coolant has a dielectric conductivity of less than 30 μS / cm as determined after aging the aforementioned single-layer or multi-layer tubular structure at 80 °C for 168 hours in contact with the aforementioned coolant.

[0075] In one embodiment, it includes at least one layer (I) containing at least one thermoplastic polymer selected from non-functionalized polyolefin, thermoplastic vulcanizate (TPV), fluoropolymer (such as ETFE), polyphenylene sulfide (PPS), and polyphthalamide (PPA). The aforementioned coolant has a dielectric conductivity of less than 30 μS / cm as determined after aging the aforementioned single-layer or multi-layer tubular structure at 80 °C for 168 hours in contact with the aforementioned coolant.

[0076] In another embodiment, it includes at least one layer (I) containing at least one thermoplastic polymer selected from non-functionalized polyolefin, thermoplastic vulcanizate (TPV), polyphenylene sulfide (PPS), and polyphthalamide (PPA). The aforementioned coolant has a dielectric conductivity of less than 30 μS / cm as determined after aging the aforementioned single-layer or multi-layer tubular structure at 80 °C for 168 hours in contact with the aforementioned coolant.

[0077] In the first variant, the aforementioned structure is single-layered, and thus layer (I) is in contact with the coolant.

[0078] In the second variant, the aforementioned structure is multi-layered, and thus layer (I) is the inner layer in contact with the coolant.

[0079] In one embodiment of this second variant, the aforementioned structure is multi-layered, which includes an outer layer (II) containing at least one thermoplastic polymer, particularly polyamide.

[0080] In one embodiment, the aforementioned structure is multi-layered, which includes an outer layer (II) made of at least one thermoplastic polymer, particularly polyamide.

[0081] Advantageously, the aforementioned structure is two-layered, and thus consists of layer (II) / / (I) from the outside to the inside.

[0082] Advantageously, the aforementioned inner layer (I) consists of at least one of the aforementioned thermoplastic polymers selected from polyolefin, thermoplastic vulcanizate (TPV), fluoropolymer, polyphenylene sulfide (PPS), and polyphthalamide (PPA).

[0083] Advantageously, the aforementioned outer layer (II) consists of at least one of the aforementioned thermoplastic polymers, particularly polyamide.

[0084] Advantageously, the aforementioned inner layer (I) consists of at least one of the aforementioned thermoplastic polymers selected from polyolefin, thermoplastic vulcanizate (TPV), fluoropolymer, polyphenylene sulfide (PPS), and polyphthalamide (PPA), and the aforementioned outer layer (II) consists of at least one of the aforementioned thermoplastic polymers, particularly polyamide.

[0085] The outer layer (II) may also include additives or conventional additives, especially in addition to the aforementioned thermoplastic substances.

[0086] Among the additives, those selected particularly from catalysts, antioxidants, heat stabilizers, UV stabilizers, light stabilizers, lubricants, fillers, plasticizers, flame retardants, nucleating agents, dyes, conductive agents, heat conductors, impact resistance improvers or mixtures thereof may be mentioned.

[0087] The outer layer (II) is suitably composed of at least 90% by weight, preferably at least 92% by weight, more preferably at least 95% by weight, very preferably at least 98% by weight of a thermoplastic polymer, in particular polyamide.

[0088] In one embodiment, the aforementioned tubular structure releases ions in an amount of 700 mg / kg or less, more particularly 500 mg / kg or less, especially 300 mg / kg or less, and particularly 100 mg / kg or less, into the aforementioned coolant, and the amount of the released ions is determined by inductively coupled plasma mass spectrometry (ICP-MS) or ion chromatography including the aforementioned coolant in an 8×1 mm 2 single-layer tube.

[0089] Regarding the polyamide of the outer layer (II) The polyamide (PA) may be a homopolyamide or a copolyamide or a mixture thereof.

[0090] Advantageously, the polyamide is selected from semi-crystalline aliphatic polyamides, cycloaliphatic polyamides, and semi-aromatic polyamides (polyphthalamides or PPA).

[0091] In particular, the polyamide of layer (II) is selected from semi-crystalline aliphatic polyamides and semi-aromatic polyamides (PPA) having an average number of carbon atoms per nitrogen atom of C4 to C15. [[ID=2,6]]

[0092] The semi-crystalline aliphatic polyamide of the outer layer (II) "Semicrystalline polyamide" is generally solid at ambient temperature, softens during temperature increase, especially after passing through its glass transition temperature (Tg), and can melt rapidly when passing through its so-called melting temperature (Tm), and becomes solid again when the temperature decreases below its crystallization temperature.

[0093] Tg, Tc and Tm are determined by differential scanning calorimetry (DSC) in accordance with Standards 11357-2:2013 and 11357-3:2013 respectively.

[0094] The number average molecular weight Mn of the aforementioned semicrystalline polyamide is preferably in the range of 10,000 to 85,000, particularly 10,000 to 60,000, preferentially 10,000 to 50,000, and even more preferentially 12,000 to 50,000. These Mn values are determined in m-cresol in accordance with Standard ISO 307:2007, but can correspond to an intrinsic viscosity of 0.8 or more with the solvent changed (using m-cresol instead of sulfuric acid, and the temperature is 20 °C).

[0095] The nomenclature used to define polyamides is described in Standard ISO 1874-1:2011 "Plastics - Polyamide (PA) Molding and Extrusion Materials - Part 1: Naming System", particularly on page 3 (Tables 1 and 2), and is well-known to those skilled in the art.

[0096] The term polyamide includes both homopolyamides and copolyamides.

[0097] The aforementioned at least one semicrystalline aliphatic polyamide is obtained from the polycondensation of at least one lactam, or from the polycondensation of at least one amino acid, or from the polycondensation of at least one diamine X and at least one dicarboxylic acid Y or a mixture thereof.

[0098] When the at least one semi-crystalline aliphatic polyamide described above is obtained from polycondensation of at least one lactam, the at least one lactam described above can be selected from lactams having 8 to 18 carbon atoms, preferably 10 to 18 carbon atoms, more preferably 10 to 12 carbon atoms. Lactams having 8 to 18 carbon atoms are, inter alia, decanolactam, undecanolactam and lauryllactam.

[0099] Therefore, when the at least one semi-crystalline aliphatic polyamide described above is obtained from polycondensation of at least one lactam, it can contain a single lactam or several lactams.

[0100] Advantageously, the at least one semi-crystalline aliphatic polyamide described above is obtained from polycondensation of a single lactam, and the lactam described above is selected from lauryllactam and undecanolactam, preferably lauryllactam.

[0101] When the at least one semi-crystalline aliphatic polyamide described above is obtained from polycondensation of at least one amino acid, the at least one amino acid described above can be selected from amino acids having 8 to 18 carbon atoms, preferably 10 to 18 carbon atoms, more preferably 10 to 12 carbon atoms.

[0102] Amino acids having 8 to 18 carbon atoms are, inter alia, 9-aminononanoic acid, 10-aminodecanoic acid, 10-aminoundecanoic acid, 12-aminododecanoic acid and 11-aminoundecanoic acid, and derivatives thereof, especially N-heptyl-11-aminoundecanoic acid.

[0103] Therefore, when the at least one semi-crystalline aliphatic polyamide described above is obtained from polycondensation of at least one amino acid, it can contain a single amino acid or several amino acids.

[0104] Advantageously, the semi-crystalline aliphatic polyamide described above is obtained from polycondensation of a single amino acid, and the amino acid described above is selected from 10-aminodecanoic acid, 11-aminoundecanoic acid and 12-aminododecanoic acid, preferably 11-aminoundecanoic acid.

[0105] When at least one of the aforementioned semi-crystalline aliphatic polyamides is obtained from the polycondensation of at least one diamine X and at least one aliphatic dicarboxylic acid Y, the diamine X may be as defined above, and the aliphatic dicarboxylic acid Y may be as defined above.

[0106] In one embodiment, the polyamide of layer (II) is selected from semi-crystalline aliphatic polyamides and semi-aromatic polyamides (PPAs) having an average number of carbon atoms per nitrogen atom of C4 to C15.

[0107] In particular, the polyamide of layer (II) is a semi-crystalline aliphatic polyamide having an average number of carbon atoms per nitrogen atom of C8 to C15, particularly C9 to C15, particularly C10 to 15.

[0108] In particular, the semi-crystalline aliphatic polyamides of layer (II) are selected from PA610, PA612, PA614, PA618, PA1010, PA1012, PA1014, PA1018, PA1210, PA1212, PA1214, PA1218, PA11 and PA12, particularly PA612, PA614, PA618, PA1010, PA1012, PA1014, PA1018, PA1210, PA1212, PA1214, PA1218, PA11 and PA12, especially PA614, PA618, PA1010, PA1012, PA1014, PA1018, PA1210, PA1212, PA1214, PA1218, PA11 and PA12.

[0109] Advantageously, the semi-crystalline aliphatic polyamide of layer (II) is selected from PA11 and PA12.

[0110] The semi-aromatic polyamide of the outer layer (II) It is as defined for the PPA of the inner layer (I).

[0111] In another embodiment of this second variant, the aforementioned structure is multilayered and comprises an outer layer (II) containing at least one thermoplastic polymer, in particular polyamide, and a binder layer (III) located between the aforementioned inner layer (I) and the aforementioned outer layer (II).

[0112] Advantageously, the aforementioned structure is three-layered and thus consists of layer (II) / / binder / / (I) from the outside to the inside.

[0113] Advantageously, the aforementioned inner layer (I) consists of at least one of the aforementioned thermoplastic polymers selected from polyolefin, thermoplastic vulcanizate (TPV), fluoropolymer, polyphenylene sulfide (PPS) and polyphthalamide (PPA).

[0114] Advantageously, the aforementioned outer layer (II) consists of at least one of the aforementioned thermoplastic polymers, in particular polyamide.

[0115] Advantageously, the aforementioned inner layer (I) consists of at least one of the aforementioned thermoplastic polymers selected from polyolefin, thermoplastic vulcanizate (TPV), fluoropolymer, polyphenylene sulfide (PPS) and polyphthalamide (PPA), and the aforementioned outer layer (II) consists of at least one of the aforementioned thermoplastic polymers, in particular polyamide.

[0116] In one embodiment of this second variant and its embodiments, the inner layer (I) has a thickness corresponding to 5% to 95% of the total thickness of the aforementioned structure.

[0117] In another embodiment of this second variant and its embodiments, the outer layer (II) has a thickness of at least 5% of the total thickness of the aforementioned structure.

[0118] In yet another embodiment of this second variant and its embodiments, the inner layer (I) has a thickness of 5% to 95% of the total thickness of the aforementioned structure, and the outer layer (II) has a thickness of at least 5% of the total thickness of the aforementioned structure.

[0119] Regarding the binder layer The aforementioned binder layer can include a binder as described, in particular, in European Patent No. 1452307, European Patent No. 1162061, European Patent No. 1216826, and European Patent No. 0428833.

[0120] It is implicitly shown that layer (II) and (binder) or (I) and (binder) adhere to each other. The binder layer is intended to be interposed between two layers that do not adhere to each other or that have difficulty adhering to each other.

[0121] Binders include, for example, but are not limited to, compositions based on 50% Mn16000 copolyamide 6 / 12 (mass ratio 70 / 30) and 50% Mn16000 copolyamide 6 / 12 (mass ratio 30 / 70), compositions based on PP (polypropylene) grafted with maleic anhydride known under the name Admer® QF551A from Mitsui Chemicals, Inc., PA610 (Mn30000, as defined elsewhere), and 36% (Mn28000) PA6 and 1.2% organic stabilizer (consisting of 0.8% phenolic Lowinox® 44B25 from Great Lakes, 0.2% phosphite Irgafos® 168 from BASF, and 0.2% UV stabilizer Tinuvin® 312 from BASF), compositions based on PA612 (Mn29000, as defined elsewhere), and 36% PA6 (Mn28000, as defined elsewhere) and 1.2% organic stabilizer (consisting of 0.8% phenolic Lowinox® 44B25 from Great Lakes, 0.2% phosphite Irgafos® 168 from BASF, and 0.2% UV stabilizer Tinuvin® 312 from BASF), compositions based on PA610 (Mn30000, as defined elsewhere), and 36% PA12 (Mn35000, as defined elsewhere) and 1.2% organic stabilizer (consisting of 0.8% phenolic Lowinox® 44B25 from Great Lakes, 0.2% phosphite Irgafos® 168 from BASF, and 0.2% UV stabilizer Tinuvin® 312 from BASF), compositions of 40% PA6 (Mn28000, as defined elsewhere), 40% PA12 (Mn35000, as defined elsewhere), and 20% functionalized EPR Exxelor® VA1801 (Exxon), and 1.2% organic stabilizer (consisting of 0.8% phenolic Lowinox® 44B25 from Great Lakes, 0.2% phosphite Irgafos® 168 from BASF, and 0.2% UV stabilizer Tinuvin® 312 from BASF), and 0.Comprising 2% of the UV stabilizer Tinuvin® 312, or 40% of PA6.10 (Mn 30,000, as defined elsewhere), 40% of PA6 (Mn 28,000, as defined elsewhere) and 20% of an impact modifier of the ethylene / ethyl acrylate / anhydride type with a mass ratio of 68.5 / 30 / 1.5 (MFI 6 at 190 °C with 2.16 kg), and 1.2% of an organic stabilizer (comprising 0.8% of the phenol Lowinox® 44B25 from Great Lakes, 0.2% of the phosphite Irgafos® 168 from BASF and 0.2% of the UV stabilizer Tinuvin® 312 from BASF) may also be a composition based thereon.

[0122] It is very clear that the multilayer tubular structure of the present invention can include other layers, provided that layer (I) is always the inner layer and layer (II) is always the outer layer, and there is adhesion between the various layers.

[0123] For example, it is possible to consider a structure of the (from the outside to the inside) type: (II) / / binder / / PA / / binder / / / (I).

[0124] Whatever the above tubular structure, the aforementioned tubular structure has an amount of soluble and insoluble extracts released into the aforementioned coolant of less than 1 g / m 2 after aging the aforementioned multilayer tubular structure in contact with the aforementioned coolant at 80 °C for 1200 hours.

[0125] According to another aspect, the present invention relates to a tubular structure as defined above for fuel cell cooling.

[0126] All the properties defined for the structure are effective for its use.

Examples

[0127] The present invention will now be explained in more detail by the following examples, which are not limiting.

[0128] The following structures were prepared by extrusion: The multi-layer tubes are manufactured by co-extrusion. A McNeil industrial multi-layer extrusion line equipped with five extruders connected to a multi-layer extrusion head with a spiral mandrel is used.

[0129] The screws used are single extrusion screws with a screw profile suitable for polyamide. In addition to the five extruders and the multi-layer extrusion head, the extrusion line includes - a die punch assembly arranged at the end of the co-extrusion head, where the inner diameter of the die and the outer diameter of the punch are selected as a function of the structure to be manufactured and the materials that make it up, as well as the dimensions of the tube and the line speed; - a vacuum tank with an adjustable vacuum level and. Water generally maintained at 20 °C circulates through this tank, and a gauge for bringing the tube to its final dimensions is immersed in this water. The diameter of the gauge is adapted to the dimensions of the tube to be manufactured and is typically 8.5 to 10 mm for a tube with an outer diameter of 8 mm and a thickness of 1 mm; - a series of cooling tanks in which water is maintained at about 20 °C to cool the tube along the path from the head to the draw bench; - a diameter measuring device; - a draw bench.

[0130] A configuration with five extruders is used to manufacture tubes in the range of 2 to 5 layers. For structures with less than 5 layers, the same material is supplied to some of the extruders.

[0131] For structures containing 6 layers, an additional extruder is connected to manufacture the inner layer in contact with the fluid, and a spiral mandrel is added to the existing head.

[0132] Before the test, to ensure the best properties of the tube and good extrusion quality, it is confirmed that the extruded material has a residual moisture content before extrusion of less than 0.08%. Otherwise, an additional step of drying the material before the test is generally carried out at 80 °C overnight in a vacuum dryer.

[0133] The tube that meets the characteristics described in this patent application is taken out after the extrusion parameters have stabilized and the target dimensions of the tube no longer change over time. The diameter is monitored by a laser diameter measuring instrument installed at the end of the line.

[0134] Generally, the line speed is usually 20 m / min. It generally varies between 5 and 100 m / min.

[0135] The screw speed of the extruder depends on the layer thickness and the diameter of the screw, as is known to those skilled in the art.

[0136] Generally, the temperatures of the extruder and the tools (head and connector) should be set to be well above the melting temperature of the composition under consideration, so that as a result, they remain in a molten state and thus are prevented from solidifying and blocking the machine.

[0137] The tubular structure was tested with respect to various parameters (Table 1).

[0138] The amounts of soluble and insoluble extracts, conductivity, total amount of extractable ions, resistance to coolant, and impact and rupture at 110 °C after 1200 hours at 80 °C were also evaluated. PA11 = Rilsan BESN P123 Black TL (Arkema) Fluoropolymer: ETFE EP7000 (Daikin Chemicals) PA9T: Genestar N1001D (Kuraray) Binder 1: Orevac® 18342N (SK Functional Polymer) Binder 2: Orevac® 18729 (SK functional polymer) HDPE = Lupolen® 4261 AIM (LyondellBasell) PP = SABIC® PP 4935 (Sabic) TPV: Santoprene® 101-87 (Exxonmobil) [Table 1] TIFF2025524393000001.tif114170NT: Not tested

[0139] Table 2 shows the tests used and the classification of the results. [Table 2] TIFF2025524393000002.tif122170

Claims

1. A single-layer or multi-layer tubular structure for transporting a coolant, comprising at least one inner layer (I) comprising at least one thermoplastic polymer selected from polyolefins, thermoplastic vulcanized products (TPVs), fluoropolymers, polyphenylene sulfide (PPS), and polyphthalamide (PPA), wherein the tube is intended for fuel cell cooling, and the coolant has a dielectric conductivity of less than 30 μS / cm, determined after aging the single-layer or multi-layer tubular structure in contact with the coolant at 80°C for 168 hours.

2. A single-layer or multi-layer tubular structure for transporting coolant according to claim 1, characterized in that it is a single layer.

3. A single-layer or multi-layer tubular structure for transporting a coolant according to claim 1, characterized in that it is multilayer and comprises an outer layer (II) containing at least one thermoplastic polymer.

4. The single-layer or multilayer tubular structure according to any one of claims 1 to 3, characterized in that the thermoplastic polymer of the inner layer (I) is a polyolefin selected from unfunctionalized polyolefins, functionalized polyolefins, and mixtures thereof.

5. A single-layer or multilayer tubular structure according to any one of claims 1 to 3, characterized in that the inner layer (I) polyolefin is a non-functionalized polyolefin.

6. The single-layer or multilayer tubular structure according to claim 5, characterized in that the non-functionalized polyolefin is selected from polyethylene and polypropylene.

7. The single-layer or multilayer tubular structure according to claim 6, characterized in that the non-functionalized polyolefin is selected from high-density polyethylene.

8. A multilayer tubular structure according to any one of claims 1 to 3, characterized in that the thermoplastic polymer of the inner layer (I) is a fluoropolymer.

9. The multilayer tubular structure according to claim 8, characterized in that the thermoplastic polymer of the inner layer (I) is selected from poly(vinylidene fluoride) (PVDF), polytetrafluoroethylene (PTFE), polychlorotrifluoroethylene (PCTFE), ethylenetetrafluoroethylene, a thermopolymer of tetrafluoroethylene, ethylene, and hexafluoropropylene (EFEP), a copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether, and mixtures thereof.

10. A multilayer tubular structure according to any one of claims 1 to 3, characterized in that the thermoplastic polymer of the inner layer (I) is polyphthalamide (PPA).

11. The multilayer tubular structure according to claim 10, characterized in that the polyphthalamide (PPA) is selected from PA9T, PA6T, PA11 / 10T, PA12 / 10T, PA11 / 12T, PA12 / 12T, PA610 / 10T, PA612 / 10T, PA1010 / 10T, PA1012 / 10T, PA1212 / 10T, PA610 / 12T, PA612 / 12T, PA1010 / 12T, PA1012 / 12T, and PA1212 / 12T.

12. The multilayer tubular structure according to claim 3, characterized in that the polyamide of layer (II) is selected from semicrystalline aliphatic polyamides and semi-aromatic polyamides (PPAs) having an average number of carbon atoms per nitrogen atom of C4 to C15.

13. The multilayer tubular structure according to claim 12, characterized in that the polyamide of layer (II) is a semicrystalline aliphatic polyamide having an average number of carbon atoms per nitrogen atom of C8 to C15.

14. The multilayer tubular structure according to claim 13, characterized in that the semicrystalline aliphatic polyamide is selected from PA610, PA612, PA614, PA618, PA1010, PA1012, PA1014, PA1018, PA1210, PA1212, PA1214, PA1218, PA11, and PA12.

15. The multilayer tubular structure according to claim 13 or 14, characterized in that the semicrystalline aliphatic polyamide is selected from PA11 and PA12.

16. The multilayer tubular structure according to claim 3, characterized in that the inner layer (I) has a thickness corresponding to 5% to 95% of the total thickness of the structure.

17. The multilayer tubular structure according to claim 3, characterized in that the outer layer (II) has a thickness of at least 5% of the total thickness of the structure.

18. The multilayer tubular structure according to claim 16 or 17, characterized in that the inner layer (I) has a thickness of 5% to 95% of the total thickness of the structure, and the outer layer (II) has a thickness of at least 5% of the total thickness of the structure.

19. The multilayer tubular structure according to claim 3, characterized in that the tubular structure includes a binder layer (III) located between the inner layer (I) and the outer layer (II).

20. After the tubular structure has been in contact with the coolant, and the multilayer tubular structure has been aged at 80°C for 1200 hours, the amount of material added is 1 g / m². ２ The single-layer or multilayer tubular structure according to claim 1, characterized in that it has an amount of soluble extract and insoluble extract released into the coolant of less than .

21. Use of the tubular structure according to claim 1 for cooling a fuel cell.