Flame retardant multi-layer tubular structure for cooling batteries in electric vehicles or batteries in stationary energy storage systems

Abstract

The present invention relates to a flame-retardant multi-layer tubular structure for cooling the battery of an electric vehicle or a battery of a stationary energy storage system, said structure comprising at least two layers, namely an inner layer (I) and an outer layer (II), the inner layer (I) containing at least 40% by weight of at least one thermoplastic polymer P1 chosen from polyolefins and thermoplastic elastomers, and up to 5% by weight of a compound chosen from heat stabilizers and metal deactivators, or a mixture thereof, and the outer layer (II) comprises a composition based on at least one primary polyamide, said composition comprising a) at least 50% by weight of at least one polyamide, b) 15-38% by weight of at least one flame retardant, c) 4-20% by weight, in particular 4-15% by weight of a polyolefin, d) 0-10% by weight, in particular 0.1-10% by weight of at least one plasticizer, e) 0-5% by weight, in particular 0.1-5% by weight of at least one additive, the sum of a)+b)+c)+d)+e) being equal to 100%.

Description

[Technical field]

[0001] The present invention relates to a flame retardant multi-layer tubular structure for cooling batteries in electric vehicles or batteries in stationary energy storage systems.

[0002] One of the desired objectives, especially in the automotive sector, is to propose less and less polluting vehicles, so the goal is to gradually replace internal combustion vehicles (for example gasoline or other diesel vehicles) with electric or hybrid vehicles equipped with batteries.

[0003] Indeed, batteries prove to be a relatively complex component of a vehicle: depending on the location of the battery in the vehicle, it may need to be protected from shocks and the external environment (e.g. very high temperatures and fluctuating humidity), and also to avoid the risk of fire.

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

[0005] Another desired objective, particularly in stationary energy storage systems, is to have available a system capable of facilitating the production of renewable energy, running electric vehicles, or quite simply, strengthening the electrical network.

[0006] Stationary storage thus becomes strategic as it helps ensure a balance between electricity production and consumption: energy is stored during off-peak or high production periods and then released at a later time when demand is high or production is low.

[0007] Thus, electric or hybrid vehicles, or energy storage systems, require devices for cooling the batteries, or in general, systems consisting of multi-layered tubular lines.

[0008] To protect the integrity of the vehicle or system, the lines must be fire resistant. These lines, especially for electric vehicles, fall into two categories: lines inside the battery pack and lines outside the battery pack. The specifications for lines outside the battery pack are more stringent and require resistance to zinc chloride (under the hood environment) and low temperature shock.

[0009] In these battery cooling lines, or cooling lines of stationary energy storage systems, generally a coolant is transported, and long-chain polyamides are well suited for such lines. They show good service life in contact with the coolant (90-110°C), while: - Flexible construction, which allows for easy installation in vehicles -Structure resistant to harsh under-hood environments results.

[0010] Polyamides can also be made fire resistant by adding flame retardant fillers using compounding procedures, but this fire resistance technique does not provide the key properties required for battery or stationary energy storage system cooling applications, as such polyamides are brittle and the tubular lines so formed have insufficient impact strength.

[0011] This objective is achieved by the development of multi-layer solutions, which make it possible to combine all the above mentioned properties and to meet the complex specifications of the applications.

[0012] The present invention therefore relates to a flame-retardant multi-layer tubular structure for cooling a battery of an electric vehicle or a battery of a stationary energy storage system, said structure comprising at least two layers, namely an inner layer (I) and an outer layer (II), the inner layer (I) contains at least 40% by weight, based on the total weight of said layer (I), of at least one thermoplastic polymer P1 selected from polyolefins, thermoplastic elastomers and blends thereof, and up to 5% by weight of a compound or mixtures thereof selected from heat stabilizers and metal deactivators, the outer layer (II) comprises at least one composition based on a primary polyamide, which composition comprises, by weight, based on the total weight of the layer (II): a) at least 50% by weight of at least one polyamide; b) 15 to 38% by weight of at least one flame retardant; c) 4 to 20% by weight, in particular 4 to 15% by weight, of polyolefins; d) 0 to 10% by weight, in particular 0.1 to 10% by weight, of at least one plasticizer, e) 0 to 5% by weight, in particular 0.1 to 5% by weight, of at least one additive, Contains, and the sum of a)+b)+c)+d)+e) equals 100%.

[0013] The present invention therefore relates to a flame-retardant multi-layer tubular structure for cooling a battery of an electric vehicle or a battery of a stationary energy storage system, said structure comprising at least two layers, namely an inner layer (I) and an outer layer (II), the inner layer (I) contains at least 40% by weight, based on the total weight of said layer (I), of at least one thermoplastic polymer P1 selected from polyolefins, thermoplastic elastomers and blends thereof, the outer layer (II) comprises at least one composition based on a primary polyamide, which composition comprises, by weight, based on the total weight of the layer (II): a) at least 50% by weight of at least one polyamide; b) 15 to 38% by weight of at least one flame retardant; c) 4 to 20% by weight, in particular 4 to 15% by weight, of polyolefins; d) 0 to 10% by weight, in particular 0.1 to 10% by weight, of at least one plasticizer, e) 0 to 5% by weight, in particular 0.1 to 5% by weight, of at least one additive, Contains, and the sum of a)+b)+c)+d)+e) equals 100%.

[0014] According to one embodiment, the present invention relates to a flame-retardant multi-layer tubular structure for cooling a battery of an electric vehicle or a battery of a stationary energy storage system, said structure comprising at least two layers, namely an inner layer (I) and an outer layer (II), the inner layer (I) contains at least 20% by weight of a polyolefin, optionally 0 to 80% by weight of an elastomer, and optionally 0 to 5% by weight of a heat stabilizer, based on the total weight of said layer (I); the outer layer (II) comprises at least one composition based on a primary polyamide, which composition comprises, by weight, based on the total weight of the layer (II): a) at least 50% by weight of at least one polyamide; b) 15 to 38% by weight of at least one flame retardant; c) 4 to 20% by weight, in particular 4 to 15% by weight, of polyolefins; d) 0 to 10% by weight, in particular 0.1 to 10% by weight, of at least one plasticizer, e) 0 to 5% by weight, in particular 0.1 to 5% by weight, of at least one additive, Contains, and the sum of a)+b)+c)+d)+e) equals 100%.

[0015] The inventors have unexpectedly found that a multi-layer structure comprising at least two layers, an inner layer made of an optionally stabilized polyolefin and an outer layer based on polyamide containing a flame retardant, allows the formation of a structure having a combination of fire resistance, good service life even in long contact with the coolant, flexibility, resistance to zinc chloride and good burst strength, essential properties for applications in cooling the batteries of electric vehicles or stationary energy storage systems.

[0016] In one embodiment, the inner layer (I) contains at least 40% by weight, in particular at least 50% by weight, in particular at least 60% by weight, of at least one thermoplastic polymer P1 selected from polyolefins, thermoplastic elastomers and blends thereof, based on the total weight of the layer (I), and up to 5% by weight of a compound or mixtures thereof selected from heat stabilizers and metal deactivators.

[0017] In one embodiment, the inner layer (I) contains at least 40% by weight, in particular at least 50% by weight, especially at least 60% by weight, of at least one polyolefin, based on the total weight of the layer (I).

[0018] In one embodiment, the inner layer (I) contains up to 5 wt. % of a heat stabilizer, based on the total weight of the layer (I), that is, from 0 wt. % (inclusive) to 5 wt. % (inclusive) of a heat stabilizer.

[0019] The expression "multi-layer tubular structures" should be understood to mean annular structures or pipe structures of cylindrical and circular cross section.

[0020] The term "battery" should be understood to mean a set of electrical storage cells (also called a "battery pack").

[0021] The term "vehicle" should be understood to mean a car, truck, train or aircraft, in particular a car.

[0022] The expression "stationary energy storage system" is to be understood to mean, for example, the storage of electricity produced by renewable energies, improving the stability of the electrical network or supporting private or commercial self-use of electricity, which is achieved by mechanical storage (e.g. pumping stations, compressed air or inertial storage, chemical storage or electrochemical storage.

[0023] The term "flame retardant" means that the tubular structure has a flame retardant property in the UL94 test (IEC 60695-11-10) of V0 at 0.8 mm.

[0024] The UL 94 test (usually performed on a bar of one product) is performed here on a single-layer structure (single-layer tube) or on a multi-layer structure, in particular on a three-layer tube, in which the flame is in contact with only the outer layer of the tube, the dimensions of the layers of this three-layer tube, respectively, from the outer layer to the inner layer, are as follows: 0.15mm / / 0.10mm / / 0.75mm, or 0.350mm / / 0.10mm / / 0.55mm.

[0025] About Polyamide The nomenclature used to define polyamides is set out in ISO standard 1874-1:2011, "Plastics - Polyamide (PA) molding and extrusion materials - Part 1: Designation", particularly page 3 (Tables 1 and 2), and is well known to those skilled in the art.

[0026] According to the present patent application, the term "polyamide" (also written "PA") covers: Homopolymers, Copolymers, or copolyamides (based on different amide units, for example copolyamide 6 / 12 with amide units derived from lactam-6 and from lactam-12) Polyamide alloy, where polyamide is the main component.

[0027] There is also a category of copolyamides in the broad sense, which, although not preferred, fall within the scope of the present invention. These are copolyamides that contain not only amide units (considered to be copolyamides in the broad sense due to the fact that they are predominant), but also non-amide units, such as ether units. The best-known examples are PEBA or polyether block amides and their copolyamide ester ether, copolyamide ether or copolyamide ester modifications. Among these, PEAB-12 (where the polyamide units are the same as those of PA12) and PEAB-6.12 (where the polyamide units are the same as those of PA6.12) can be mentioned.

[0028] The polyamide may be an amorphous or semi-crystalline polyamide.

[0029] Amorphous polyamides, within the meaning of the present invention, refer to polyamides which have only a glass transition temperature (no melting point (Tm)) or which have a glass transition temperature and a melting point such that the enthalpy of crystallization is less than 30 J / g, in particular less than 20 J / g, preferably less than 15 J / g, measured during a cooling step at a rate of 20 k / min according to ISO standard 11357-3:2013.

[0030] Semicrystalline polyamide, within the meaning of the present invention, is a polyamide which has a glass transition temperature, determined by dynamic mechanical analysis (DMA) according to ISO standard 6721-11:2019, a melting point (Tm), determined according to ISO standard 11357-3:2013, and an enthalpy of crystallization, measured during a cooling step at a rate of 20 K / min by DSC, according to ISO standard 11357-3:2013, of more than 30 J / g, preferably more than 35 J / g.

[0031] In a first alternative form, the polyamide may result from the polycondensation of at least one aminocarboxylic acid containing from 6 to 18 carbon atoms, preferably from 9 to 18 carbon atoms, more preferably from 10 to 18 carbon atoms, even more preferably from 10 to 12 carbon atoms, and may thus be chosen from 6-aminohexanoic acid, 7-aminoheptanoic acid, 8-aminooctanoic acid, 9-aminononanoic acid, 10-aminodecanoic acid, 11-aminoundecanoic acid, 12-aminododecanoic acid, 13-aminotridecanoic acid, 14-aminotetradecanoic acid, 15-aminopentadecanoic acid, 16-aminohexadecanoic acid, 17-aminoheptadecanoic acid or 18-aminooctadecanoic acid.

[0032] It preferably results from the polycondensation of one aminocarboxylic acid.

[0033] In a second alternative form, the polyamide may result from the polycondensation of at least one lactam containing from 6 to 18 carbon atoms, preferably from 9 to 18 carbon atoms, more preferably from 10 to 18 carbon atoms, even more preferably from 10 to 12 carbon atoms.

[0034] It preferably results from the polycondensation of one lactam.

[0035] In a third alternative form, the polyamide can be obtained from the polycondensation of at least one diamine X with at least one dicarboxylic acid Y, where the diamine X may be aliphatic, cycloaliphatic or aromatic, in particular aliphatic, having from 4 to 36 carbon atoms, advantageously from 6 to 18 carbon atoms, advantageously from 6 to 12 carbon atoms, advantageously from 10 to 12 carbon atoms, and the dicarboxylic acid Y may be aliphatic, cycloaliphatic or aromatic, in particular aliphatic, having from 4 to 36 carbon atoms, advantageously from 6 to 18 carbon atoms, advantageously from 6 to 12 carbon atoms, advantageously from 10 to 12 carbon atoms, forming repeat units XY.

[0036] The aliphatic diamines used are those having at least 4 carbon atoms and having a linear backbone.

[0037] This linear backbone may, where appropriate, carry one or more methyl and / or ethyl substituents, in which case the term "branched aliphatic diamine" is used. If the backbone does not carry any substituents, the aliphatic diamine is called a "linear aliphatic diamine".

[0038] The aliphatic diamine used to obtain this repeat unit XY, whether or not it has methyl and / or ethyl substituents in the main chain, has from 4 to 36 carbon atoms, advantageously from 4 to 18 carbon atoms, advantageously from 6 to 18 carbon atoms, advantageously from 6 to 14 carbon atoms.

[0039] When the diamine is a linear aliphatic diamine, it has the formula H2N-(CH2) x It corresponds to -NH2, which may be selected, for example, from butanediamine, pentanediamine, hexanediamine, heptanediamine, octanediamine, nonanediamine, decanediamine, undecanediamine, dodecanediamine, tridecanediamine, tetradecanediamine, hexadecanediamine, octadecanediamine, and octadecenediamine. The linear aliphatic diamines just mentioned may be biobased within the meaning of ASTM standard D6866.

[0040] When the diamine is a branched aliphatic diamine, it may in particular be 2-methylpentanediamine, 2-methyl-1,8-octanediamine, or (2,2,4- or 2,4,4-)trimethylhexanediamine.

[0041] The aliphatic diamines used are bis(3,5-dialkyl-4-aminocyclohexyl)methane, bis(3,5-dialkyl-4-aminocyclohexyl)ethane, bis(3,5-dialkyl-4-aminocyclohexyl)propane, bis(3,5-dialkyl-4-aminocyclohexyl)butane, bis(3-methyl-4-aminocyclohexyl)methane, or 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane (commonly known as BMACM or MACM, hereinafter referred to as "B"). ), bis(p-aminocyclohexyl)methane (commonly known as PACM, hereinafter referred to as "P"), in particular Dicykan®, isopropylidenedi(cyclohexylamine) (commonly known as PACP), isophoronediamine (hereinafter referred to as IPD), and 2,6-bis(aminomethyl)norbornane (commonly known as BAMN), and bis(aminomethyl)cyclohexane (BAC), in particular 1,3-BAC, or especially 1,4-BAC.

[0042] It is advantageously selected from bis(3-methyl-4-aminocyclohexyl)methane or 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane (commonly known as BMACM or MACM, hereinafter designated "B"), bis(p-aminocyclohexyl)methane (commonly known as PACM, hereinafter designated P), and bis(aminomethyl)cyclohexane (BAC), in particular 1,3-BAC, or especially 1,4-BAC.

[0043] A non-exhaustive list of these alicyclic diamines is given in "Cycloaliphatic Amines" (Encyclopedia of Chemical Technology, Kirk-Othmer, 4th edition (1992), pp. 386-405).

[0044] The aromatic diamine may be selected from 1,3-xylylenediamine and 1,4-xylylenediamine.

[0045] The dicarboxylic acid may be selected from linear or branched aliphatic dicarboxylic acids.

[0046] When the dicarboxylic acid is aliphatic and linear, it may be selected from succinic acid (4), pentanedioic acid (5), adipic acid (6), heptanedioic acid (7), octanedioic acid (8), azelaic acid (9), sebacic acid (10), undecanedioic acid (11), dodecanedioic acid (12), brassylic acid (13), tetradecanedioic acid (14), hexadecanedioic acid (16), octadecanedioic acid (18), octadecenedioic acid (18), eicosanediic acid (20), docosanediic acid (22), and fatty acid dimers having 36 carbon atoms.

[0047] The above-mentioned fatty acid dimers are dimerized fatty acids obtained by oligomerization or polymerization of unsaturated monobasic fatty acids with long hydrocarbon chains (such as linoleic acid and oleic acid) (as described in particular in European Patent Application 0 471 566 (EP 0 471 566)).

[0048] When the dicarboxylic acid is alicyclic, it may have the following carbon skeleton: norbornylmethane, cyclohexane, cyclohexylmethane, dicyclohexylmethane, dicyclohexylpropane, di(methylcyclohexyl) or di(methylcyclohexyl)propane.

[0049] When the dicarboxylic acid is aromatic, it is advantageously selected from terephthalic acid (designated "T"), isophthalic acid (designated "I"), and 2,6-naphthalenedicarboxylic acid (designated "N"), or mixtures thereof. It is especially selected from terephthalic acid (designated "T"), isophthalic acid (designated "I"), or mixtures thereof.

[0050] In a fourth alternative, the polyamide is obtained from a blend of at least two of these three alternatives.

[0051] Advantageously, the polyamide is a semi-crystalline polyamide.

[0052] In a first aspect, the polyamide has an average number of carbon atoms per nitrogen atom of C4 to C 15 and semicrystalline semi-aromatic polyamides (PPAs).

[0053] In the case of homopolyamides of type XV, where X represents the units derived from diamines and Y represents the units derived from dicarboxylic acids, the average number of carbon atoms per nitrogen atom is the average number of carbon atoms present in the units resulting from diamine X and from diacid Y. Thus, PA6.12 is a PA with 9 carbon atoms per nitrogen atom, in other words a C9PA. PA6.13 is a PA with 9 carbon atoms per nitrogen atom, in other words a C9PA. 9.5 I am a PA.

[0054] In the case of copolyamides, the average number of carbon atoms per nitrogen atom is calculated according to the same principle, the calculation being carried out on a molar proportion basis from the various amide units.

[0055] Said semi-aromatic polyamide PPA, optionally modified with urea units, is chosen in particular from PA MXD6, PA MXD10 or semi-aromatic polyamides of formula X / YAr (as described in EP 1 505 099), in particular semi-aromatic polyamides of formula A / ZT, in which A is units resulting from amino acids as defined above, units resulting from lactams as defined above and units corresponding to formula (Ca diamine).(Cb diacid), where a represents the average number of carbon atoms of the diamine, Ca diamine as defined above for diamine X, b represents the average number of carbon atoms of the diacid, Cb diacid as defined above for dicarboxylic acid Y and ZT represents units resulting from the polycondensation of an aliphatic or cycloaliphatic Cx diamine as defined above for diamine X with terephthalic acid.

[0056] A / ZT in particular represents a polyamide of the formula A / 6T, A / 9T, A / 10T or A / 11T, A being as defined above, in particular PA6 / 6T, PA66 / 6T, PA6I / 6T, PA610 / 10T, PA612 / 10T, PA1010 / 10T, PA1012 / 10T, PA1212 / 10T, PA610 / 12T, PA612 / 12T, PA1010 / 12T, PA1012 / 12T, PA1212 / 12T, PA11 / 6T / 10T, PA11 / 10T, PA12 / 10T, PA11 / 12T, PA12 / 12T, PAMPMDT / 6T, PAMXDT / 10T, PAM The polyamide is selected from PMDT / 10T, PABACT / 10T, PABACT / 6T, PABACT / 10T / 6T, or PA11 / BACT / 10T, in particular 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 PA11 / 10T and PA11 / 12T.

[0057] T corresponds to terephthalic acid, MXD corresponds to m-xylylenediamine, MPMD corresponds to methylpentamethylenediamine, and BAC corresponds to bis(aminomethyl)cyclohexane.

[0058] In an alternative form of this first embodiment, the semi-crystalline aliphatic polyamide has an average number of carbon atoms per nitrogen atom of from C4 to C9.

[0059] Advantageously, the semicrystalline aliphatic polyamide is selected from PA6, PA66, PA410, PA412, PA610 and PA612, in particular from PA610 and PA612.

[0060] The polyamide in a first alternative aspect of this first embodiment can be used in the outer layer (II) of the tubular structure of the invention, which is present inside the battery pack of the electric vehicle.

[0061] The polyamide in this first alternative aspect of the first embodiment can also be used in the outer layer (II) of the tubular structure of the invention, present inside and / or outside the battery pack of the stationary energy storage system.

[0062] In a second alternative aspect of this first embodiment, the semicrystalline aliphatic polyamide has an average number of carbon atoms per nitrogen atom of C 10 ~C 15 It is.

[0063] Advantageously, the semicrystalline aliphatic polyamide is selected from PA614, PA618, PA1010, PA1012, PA1014, PA1018, PA1210, PA1212, PA1214, PA1218, PA11 or PA12, in particular from PA11 and PA12.

[0064] In a second alternative aspect of this first embodiment, the polyamide can be used in the outer layer (II) of the tubular structure of the invention, present inside and / or outside the battery pack of the electric vehicle.

[0065] In a second alternative aspect of this first embodiment, the polyamide can also be used in the inner layer (II) of the tubular structure of the invention (present inside and / or outside the battery pack of a stationary energy storage system).

[0066] In a second embodiment, the polyamide is a semi-crystalline semi-aromatic polyamide (PPA).

[0067] Advantageously, the semicrystalline, semiaromatic polyamide of this second embodiment is selected from PA6 / 6T, PA66 / 6T, PA6I / 6T, PA610 / 10T, PA612 / 10T, PA1010 / 10T, PA1012 / 10T, PA1212 / 10T, PA610 / 12T, PA612 / 12T, PA1010 / 12T, PA1012 / 12T, PA1212 / 12T, PA11 / 6T / 10T, PA11 / 10T, PA11 / 12T, PAMPMDT / 6T, PAMXDT / 10T, PAMPMDT / 10T, PABACT / 10T, PABACT / 6T, PABACT / 10T / 6T, or PA11 / BACT / 10T.

[0068] More advantageously, the semicrystalline, semiaromatic polyamide of this second embodiment is selected from 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 from PA11 / 10T and PA11 / 12T.

[0069] The polyamide of this second embodiment can be used in the outer layer (II) of the tubular structure of the invention, present inside and / or outside the battery pack of the electric vehicle or inside and / or outside the battery pack of a stationary energy storage system.

[0070] About Thermoplastic Polymer P1 Polyolefin: According to one embodiment, layer (I) may comprise at least one polyolefin.

[0071] In one embodiment, the polyolefin of the inner layer (I) may be a non-functionalized polyolefin selected from polyethylene and polypropylene, and in particular may be a high density polyethylene (HDPE).

[0072] In one embodiment, the inner layer (I) contains at least 20 wt. % of a polyolefin, optionally 0-80 wt. % of an elastomer, and optionally 0-5 wt. % of a heat stabilizer, based on the total weight of the layer (I).

[0073] The polyolefins may be functionalized or non-functionalized, or blends thereof.

[0074] For simplicity, the polyolefins are designated (B) and functionalized polyolefins (B1) and non-functionalized polyolefins (B2) are discussed below.

[0075] The non-functional polyolefins (B2) are the conventional homopolymers or copolymers of α-olefins or diolefins, such as ethylene, propylene, 1-butadiene, 1-octene or butadiene. Examples thereof include, for example: Polyethylene homopolymers and copolymers, in particular LDPE, HDPE, LLDPE (linear low density polyethylene), VLDPE (very low density polyethylene), heat resistant PE (or PE-RT: PE-Raised Temperature), and metallocene polyethylene; Propylene homopolymer or copolymer Ethylene / α-olefin copolymers, such as ethylene / propylene copolymers, EPR (short for ethylene-propylene rubber), and ethylene / propylene / diene (EPDM), Copolymers of ethylene and at least one product (which may amount to 40% by weight of the comonomer proportion) chosen from salts or esters of unsaturated carboxylic acids (for example alkyl (meth)acrylates, such as methyl acrylate) or vinyl esters of saturated carboxylic acids (for example vinyl acetate (EVA)).

[0076] The functional polyolefin (B1) may be a polymer of an α-olefin having reactive units (functionality), such as acid, aldehyde or epoxy functional groups. It is, for example, the aforementioned polyolefin (B2), grafted, copolymerized or terpolymerized with unsaturated epoxides (for example glycidyl (meth)acrylate), or with carboxylic acids or the corresponding salts or esters (for example methacrylic acid), the latter of which may be fully or partially neutralized with metals, such as Zn, or with carboxylic anhydrides (for example maleic anhydride). The functional polyolefin is, for example, a PE / EPR blend, the proportions of which may vary within a wide range, for example between 40 / 60 and 90 / 10, which blend is cografted with anhydrides, in particular maleic anhydride, for example 0.01 to 5% by weight, depending on the degree of grafting.

[0077] The functional polyolefin (B1) may be chosen from the following (co)polymers grafted with maleic anhydride or with glycidyl methacrylate (degree of grafting, for example, between 0.01 and 5% by weight): PE, PP, copolymers of ethylene with propylene, butene, hexene or octene, for example containing 35 to 80% by weight of ethylene; · Ethylene / α-olefin copolymers, such as ethylene / propylene copolymers, EPR (short for ethylene-propylene rubber), and ethylene / propylene / diene (EPDM); · Block copolymers of styrene / ethylene-butadiene / styrene (SEBS), styrene / butadiene / styrene (SBS), styrene / isoprene / styrene (SIS), or styrene / ethylene-propylene / styrene (SEPS); · Copolymers of ethylene and vinyl acetate (EVA), containing up to 40% by weight of vinyl acetate; · Copolymers of ethylene and alkyl (meth)acrylates, containing up to 40% by weight of alkyl (meth)acrylates; Copolymers of ethylene and vinyl acetate (EVA) and alkyl (meth)acrylates with a maximum of 40% by weight of comonomer.

[0078] The functional polyolefin (B1) may also be selected from ethylene / propylene copolymers, predominantly propylene, grafted with maleic anhydride and then condensed with monoaminated polyamides (or monoaminated polyamide oligomers) (products described in European Patent Application No. 0 342 066 (EP-A-0 342 066)).

[0079] The functional polyolefin (B1) may also be a copolymer or terpolymer having at least the following units: (1) ethylene, (2) an alkyl (meth)acrylate or an unsaturated carboxylic acid vinyl ester, and (3) an anhydride, such as maleic anhydride, or (meth)acrylic acid, or an epoxy, such as glycidyl (meth)acrylate.

[0080] For example, examples of the latter type of functional polyolefins include copolymers in which ethylene preferably accounts for at least 60% by weight and the termonomer (functional group) accounts for, for example, 0.1 to 10% by weight of the copolymer, examples of which are: · Ethylene / alkyl (meth)acrylate / (meth)acrylic acid or maleic anhydride or glycidyl methacrylate copolymers; · Ethylene / vinyl acetate / maleic anhydride or glycidyl methacrylate copolymers; · Ethylene / vinyl acetate or alkyl (meth)acrylate / (meth)acrylic acid or maleic anhydride or glycidyl methacrylate copolymers.

[0081] In the above copolymers, the (meth)acrylic acid may be salified with Zn or Li.

[0082] The term "alkyl (meth)acrylate" in (B1) or (B2) represents a C1 to C8 alkyl methacrylate, which may be selected from methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, methyl methacrylate, and ethyl methacrylate.

[0083] Furthermore, the above-mentioned polyolefins (B1) may be crosslinked by any suitable process or agent (diepoxy, diacid, peroxide, etc.). The term "functional polyolefin" also includes mixtures of the above-mentioned polyolefins with difunctional reactants, such as diacids, dialdehydes, diepoxy, etc., capable of reacting with the above-mentioned polyolefins, or blends of at least two functional polyolefins capable of reacting with each other.

[0084] The copolymers (B1) and (B2) can be copolymerized randomly or in blocks and can have a linear or branched structure.

[0085] It will be understood by those skilled in the art that the molecular weight, MFI index, and density of these polyolefins may vary widely. MFI is an abbreviation for Melt Flow Index. It is measured according to ASTM standard 1238.

[0086] The non-functionalized polyolefin (B2) is advantageously selected from homopolymers or copolymers of polypropylene and homopolymers or copolymers of ethylene with higher α-olefin type comonomers, such as butene, hexene, octene or 4-methyl-1-pentene. Examples include, for example, PP, high density PE, medium density PE, linear low density PE, low density PE or very low density PE. These polyethylenes are known to those skilled in the art to be produced by the "radical" process, by "Ziegler" type catalysts or, more recently, by "metallocene" catalysts.

[0087] The functional polyolefin (B1) is advantageously selected from polymers containing α-olefin units and units with reactive polar functional groups, such as epoxy, carboxylic acid or carboxylic acid anhydride functional groups. Examples of such polymers include, for example, terpolymers of ethylene, alkyl acrylates and maleic anhydride or glycidyl methacrylate, such as the products of Lotader® (SK functional polymers), or polyolefins grafted with maleic anhydride, such as the products of Orevac®, as well as terpolymers of ethylene, alkyl acrylates and (meth)acrylic acid. Examples also include homopolymers or copolymers of polypropylene grafted with carboxylic acid anhydride and then condensed with monoaminated polyamides or oligomers of monoaminated polyamides.

[0088] In one embodiment, the polyolefin is crosslinked.

[0089] In another embodiment, the polyolefin is a mechanical blend (vulcanized) of a thermoplastic olefin polymer with a matrix of polyethylene or polypropylene and an elastomer, for example a vulcanized PP / EPDM blend.

[0090] Thermoplastic elastomers: According to one embodiment, layer (I) may comprise at least one thermoplastic elastomer.

[0091] Thermoplastic elastomers include block copolymers (ether-amide block copolymers: PEBA), ether-ester block copolymers), thermoplastic polyurethanes (TPU), and thermoplastic styrene elastomers.

[0092] Said thermoplastic polymer P1 of the inner layer (I) is advantageously chosen from non-functionalized polyolefins, functionalized polyolefins, and blends thereof.

[0093] Advantageously, at least one thermoplastic polymer P1 of the inner layer (I) is a non-functionalized polyolefin, and the tubular structure then comprises a tie layer (III) between the inner layer (I) and the outer layer (II).

[0094] In one embodiment, the at least one thermoplastic polymer P1 of the inner layer (I) is a non-functionalized polyolefin chosen from polyethylene and polypropylene. It may in particular be a high density polyethylene (HDPE).

[0095] According to one embodiment, the inner layer (I) contains at least 20% by weight of polyolefin, optionally 0-80% by weight of elastomer, and optionally 0-5% by weight of a heat stabilizer, based on the total weight of said layer (I).

[0096] The polyolefin may be as defined above.

[0097] As regards the elastomer, this may in particular be a TPE (thermoplastic elastomer), that is to say a compound made from a hard thermoplastic material (of the PP, PBT or PA type) combined with a soft rubber material.

[0098] Among these, examples of thermoplastic elastomers that are suitable for the present invention include thermoplastic olefins (TPE-O), styrenics of SBS, SEBS or SEPS (TPE-S), vulcanized PP / EPDM compounds (TPE-V), copolyester compounds (TPE-E), thermoplastic polyurethanes (TPU-U) and thermoplastic polyamides (TPE-A).

[0099] Regarding binders The binder may be an adhesive composition as described in EP 2 098 580, namely At least one polyamide (designated A) having an average number of carbon atoms per nitrogen atom (C A(denoted as ) is 4 to 8.5, advantageously 4 to 7; At least one polyamide (denoted as B) having a melting point of 180°C or higher and an average number of carbon atoms per nitrogen atom (C B (denoted as ) is 7 to 10, preferably 7.5 to 9.5; At least one polyamide (denoted as C) with an average number of carbon atoms per nitrogen atom (C C ) is 9 to 18, advantageously 10 to 18; An adhesive composition comprising: At least 50% by weight of the composition is formed from one or more polyamides selected from polyamides A, B and C; the weight-weighted average enthalpy of fusion of the polyamides in the composition is greater than 25 J / g (DSC); Furthermore, for polyamides A, B and C, the average number of carbon atoms per nitrogen atom corresponds to the exact equation: A <C B <C C .

[0100] Binders can be, for example, but not limited to: compositions based on 50% of copolyamide 6 / 12 (in a weight ratio of 70 / 30) and 50% of copolyamide 6 / 12 (in a weight ratio of 30 / 70), a composition based on PP (polypropylene) grafted with maleic anhydride (known under the name Admer QF551A from Mitsui), Compositions based on PA610 and PA6 and organic stabilizers, Compositions based on PA612 and PA6 and organic stabilizers, PA610(M n 30,000, as defined elsewhere) and compositions based on PA12 and organic stabilizers, Compositions based on PA6 and PA12, the functional EPR Exxelor VA1801 (Exxon) and organic stabilizers, or Compositions based on PA610 and PA6 with an impact modifier of the ethylene / ethyl acrylate / anhydride type (ratio by weight 68.5 / 30 / 1.5) (MFI 6 at 190°C and 2.16 kg) and organic stabilizers.

[0101] The binder may also be a copolymer of a functionalized polyolefin (eg, polyethylene or polypropylene) in which the functional comonomers are selected from acid, anhydride, or epoxide groups.

[0102] The functional group is selected from compounds of carboxylic acids or compounds of anhydride derivatives of unsaturated carboxylic acids.

[0103] Examples of unsaturated dicarboxylic anhydrides are, inter alia, maleic anhydride, itaconic anhydride, citraconic anhydride, tetrahydrophthalic anhydride. Preference is given to using maleic anhydride.

[0104] However, the functional comonomer may have unsaturated epoxide type functionality.

[0105] Examples of unsaturated epoxides are in particular: Aliphatic glycidyl esters and ethers, such as allyl glycidyl ether, glycidyl vinyl ether, glycidyl maleate, glycidyl itaconate, glycidyl acrylate, and glycidyl methacrylate (GMA), and alicyclic glycidyl esters and ethers, such as 2-cyclohexen-1-yl glycidyl ether, diglycidyl cyclohexene-4,5-dicarboxylate, glycidyl cyclohexene-4-carboxylate, glycidyl 2-methyl-5-norbornene-2-carboxylate, and diglycidyl endo-cis-bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylate.

[0106] Flame retardants This is present in the composition of the outer layer (II) in an amount of 15 to 38%.

[0107] The flame retardant may be a halogen-free flame retardant, such as those described in US 2008 / 0274355, especially phosphorus-based flame retardants.

[0108] The flame retardant is in particular a metal salt selected from metal salts of phosphinic acids, metal salts of diphosphinic acids, a polymer containing at least one metal salt of phosphinic acids or a polymer containing at least one metal salt of diphosphinic acids. The flame retardant can also be a mixture of the abovementioned flame retardants.

[0109] The flame retardant may also be selected from metal salts of phosphinic acids of formula (I) and metal salts of diphosphinic acids of formula (II): TIFF2025507994000001.tif60170, where R1 and R2 are each independently a linear or branched C1-C6 alkyl group or an aryl group; R3 is a linear or branched C1-C 10 Alkylene group, C6-C 10 Arylene group, C6-C 10 Alkyl arylene group, or C6-C 10 represents an arylalkylene group, M is an ion of Mg, Ca, Al, Sb, Sn, Ge, Ti, Zn, Fe, Zr, Ce, Bi, Sr, Mn, Li, Na or K, and / or a protonated amine base; m represents an integer of 1 to 4; n represents an integer of 1 to 4; x represents an integer of 1 to 4; n and m are selected so that the salt is neutral, ie, it bears no charge.

[0110] M is preferably an ion of calcium, magnesium, aluminium or zinc.

[0111] R1 and R2 preferably represent, independently of one another, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a tert-butyl group, an n-pentyl group and / or a phenyl group.

[0112] R3 is preferably a methylene group, an ethylene group, an n-propylene group, an isopropylene group, an n-butylene group, a tert-butylene group, an n-pentylene group, an n-octylene group, an n-dodecylene group; a phenylene group, a naphthylene group; a methylphenylene group, an ethylphenylene group, a tert-butylphenylene group, a methylnaphthylene group, an ethylnaphthylene group, a tert-butylnaphthylene group; a phenylmethylene group, a phenylethylene group, a phenylpropylene group, or a phenylbutylene group.

[0113] The flame retardant may also be of the phosphonic acid type, for example an organic phosphonate (salt with an organic or inorganic cation, or a phosphonic acid ester). Preferred phosphonic acid esters are diesters of alkylphosphonic acid or phenylphosphonic acid. Examples of phosphonic acid esters to be used as flame retardants according to the invention include phosphonates of the general formula (III): JPEG2025507994000002.jpg39170, R1 is a substituted or unsubstituted alkyl, cycloalkyl, or phenyl group, where two R1 radicals may be bonded together to form a ring; R2 is a substituted or unsubstituted alkyl, cycloalkyl, or phenyl radical.

[0114] The flame retardant may also be melamine or melamine cyanurate.

[0115] The flame retardant may also be a mixture of an aluminum phosphinate flame retardant and a flame retardant synergist.

[0116] Flame retardant synergists are especially described in WO 2005 / 121234.

[0117] These may be selected from nitrogen synergists, phosphorus synergists, and phosphorus / nitrogen synergists.

[0118] Preferred nitrogen synergists include benzoguanamine, tris(hydroxyethyl)isocyanurate, allantoin, glycoluril, melamine, melamine cyanurate, dicyandiamide, guanidine, and carbodiimide.

[0119] The nitrogen synergist preferably comprises a melamine condensation product, for example melem, melam or melon, or compounds of this type with higher condensates, or mixtures thereof, which can be prepared, for example, by the process described in United States 5,985,960.

[0120] The phosphorus / nitrogen synergists may comprise reaction products of melamine with phosphoric acid or condensed phosphoric acids, or reaction products of melamine condensation products with phosphoric acid or condensed phosphoric acids, or mixtures of the specified products with flame retardant synergists, especially nitrogen synergists, especially those based on melamine.

[0121] Compounds selected from heat stabilizers and metal deactivators The heat stabilizer may be an organic stabilizer or, more generally, a combination of organic stabilizers, such as primary antioxidants of phenolic type (for example, of the type Irganox 245 or 1098 or 1010 from Ciba), secondary antioxidants of phosphite type, and in fact optionally further stabilizers, such as HALS: Hindered Amine Light Stabilizers (for example, Tinuvin 770 from Ciba), UV absorbers (for example, Tinuvin 312 from Ciba), or phenolic or phosphorus stabilizers. Amine type antioxidants, such as Naugard 445 from Crompton, or multifunctional stabilizers, such as Nylostab S-EED from Clariant, can also be used.

[0122] The organic stabilizer may be selected from, but is not limited to, the following: phenolic antioxidants, such as Irganox 245, Irganox 1010 or Irganox 1098 from Ciba, Irganox MD1024 from Ciba or Lowinox 44B25 from Great Lakes, Phosphorus stabilizers, such as phosphites, e.g. Irgafos 168 from Ciba, UV absorbers, e.g. Tinuvin 312 from Ciba, HALS (as mentioned above) Amine type stabilizers, such as Naugard 445 from Crompton, or hindered amine type, such as Tinuvin 770 from Ciba, Multifunctional stabilizers, e.g. Nylostab S-EED from Clariant.

[0123] The stabilizer can also be an inorganic stabilizer, such as a copper-based stabilizer.

[0124] Copper-based stabilizers may be selected from copper(I) chloride, copper(II) chloride, copper(I) bromide, copper(II) bromide, copper(I) iodide, copper(II) iodide, copper(I) acetate, and copper(II) acetate. Halides or acetates of other metals, such as silver, may also be combined with copper-based stabilizers. These copper-based compounds are usually combined with alkali metal halides. A well-known example is a mixture of CuI and KI, where the ratio of CuI:KI is usually 1:5 to 1:15. An example of such a stabilizer is Polyadd P201 from Ciba.

[0125] Filler details regarding copper-based stabilizers can be found in patent US 2 705 227. More recently, copper-based stabilizers (e.g. complexed copper) have appeared, such as Bruggolen H3336, Bruggolen H3337, and Bruggolen H3373 from Brueggemann.

[0126] The copper-based stabilizer is advantageously selected from copper halides, copper acetate, mixtures of copper halides or copper acetate with at least one alkali metal halide, and mixtures thereof, with a mixture of copper iodide and potassium iodide (CuI / KI) being preferred.

[0127] The metal deactivators used are the conventional deactivators used for polyolefins; for example, hydrazine can be used.

[0128] Composition of the outer layer (II) The composition comprises, by weight, based on the total weight of the composition: a) at least 50% by weight of at least one polyamide; b) 15 to 38% by weight of at least one flame retardant; c) 4 to 20% by weight, in particular 4 to 15% by weight, of polyolefins; d) 0 to 10% by weight, in particular 0.1 to 10% by weight, of at least one plasticizer, e) 0 to 5% by weight, in particular 0.1 to 5% by weight, of at least one additive, Contains, and the sum of a)+b)+c)+d)+e) equals 100%.

[0129] In one embodiment, the composition comprises, by weight, based on the total weight of the composition: a) at least 50% by weight of at least one polyamide; b) 15 to 38% by weight of at least one flame retardant; c) 4 to 15% by weight of polyolefin; d) 0 to 10% by weight, in particular 0.1 to 10% by weight, of at least one plasticizer, e) 0 to 5% by weight, in particular 0.1 to 5% by weight, of at least one additive, Contains, and the sum of a)+b)+c)+d)+e) equals 100%.

[0130] In a first alternative form of this embodiment, the composition comprises, by weight, based on the total weight of the composition: a) at least 50% by weight of at least one polyamide; b) 15 to 38% by weight of at least one flame retardant; c) 4 to 15% by weight of polyolefin; d) 0.1 to 10% by weight of at least one plasticizer; e) 0 to 5% by weight, in particular 0.1 to 5% by weight, of at least one additive, Contains, and the sum of a)+b)+c)+d)+e) equals 100%.

[0131] In a second alternative form, the composition comprises, by weight, based on the total weight of the composition: a) at least 50% by weight of at least one polyamide; b) 15 to 38% by weight of at least one flame retardant; c) 4 to 15% by weight of polyolefin; d) 0 to 10% by weight, in particular 0.1 to 10% by weight, of at least one plasticizer, e) 0.1 to 5 wt. % of at least one additive; Contains, and the sum of a)+b)+c)+d)+e) equals 100%.

[0132] In a third alternative form, the composition comprises, by weight, based on the total weight of the composition: a) at least 50% by weight of at least one polyamide; b) 15 to 38% by weight of at least one flame retardant; c) 4 to 15% by weight of polyolefin; d) 0.1 to 10% by weight of at least one plasticizer; e) 0.1 to 5 wt. % of at least one additive; Contains, and the sum of a)+b)+c)+d)+e) equals 100%.

[0133] The present invention also relates to a composition comprising, by weight, the elements a)+b)+c)+d) as described in this embodiment and its three alternative forms.

[0134] About plasticizers The plasticizer may be present in an amount of up to 10% by weight, in particular from 0.1 to 10% by weight, based on the total weight of the composition.

[0135] The plasticizer may be any plasticizer commonly used in compositions based on one or more polyamides.

[0136] In order to avoid the formation of fumes during the steps of blending the various polymers and during the steps of transforming the resulting composition, it is advantageous to use plasticizers with good thermal stability.

[0137] The plasticizer may in particular be chosen from: Benzenesulfonamide derivatives, such as the ortho- and para-isomers of n-butylbenzenesulfonamide (BBSA), ethyltoluenesulfonamide (ETSA), N-cyclohexyltoluenesulfonamide and N-(2-hydroxypropyl)benzenesulfonamide (HP-BSA); Esters of hydroxybenzoic acid, such as 2-ethylhexyl parahydroxybenzoate (EHPB) and 2-hexyldecyl parahydroxybenzoate (HDPB); esters or ethers of tetrahydrofurfuryl alcohol, for example oligoethyleneoxy-tetrahydrofurfuryl alcohol, and Esters of citric acid or of hydroxymalonic acid, for example oligoethyleneoxymalonate.

[0138] A preferred plasticizer is n-butylbenzenesulfonamide (BBSA).

[0139] Another particularly preferred plasticizer is N-(2-hydroxypropyl)benzenesulfonamide (HP-BSA), since the latter has the advantage of avoiding the formation of deposits in the extrusion screw and / or die ("die tooling") during the deformation stage by extrusion.

[0140] Of course, mixtures of plasticizers can also be used.

[0141] Additives The additives may be present in an amount of up to 5% by weight, in particular from 0.1 to 5% by weight, based on the total weight of the composition.

[0142] The at least one additive may be selected from stabilizers, dyes, processing aids, surfactants, nucleating agents, pigments, brighteners, antioxidants, lubricants, waxes, or mixtures thereof.

[0143] The stabilizer can be, for example: UV stabilizers, organic stabilizers or, more generally, combinations of organic stabilizers, for example antioxidants of the phenolic type (for example those of the Irganox® 245 or 1098 or 1010 type from Ciba-BASF), antioxidants of the phosphite type (for example Irgafos® 126, or Irgafos® 168, from Ciba-BASF), and in fact optionally further stabilizers, such as HALS: hindered amine light stabilizers (for example Tinuvin® 770, from Ciba-BASF), UV absorbers (e.g. Tinuvin® 312 from Ciba), or Phosphorus stabilizer. Amine type antioxidants (eg Naugard® 445 from Crompton) or multifunctional stabilizers (eg Nylostab® S-EED from Clariant) can also be used.

[0144] The stabilizer may be an inorganic stabilizer, such as a copper-based stabilizer. Examples of such inorganic stabilizers include copper halides and copper acetate. It is noted that other metals, such as silver, may be optionally considered, but are known to be less effective. These copper-based compounds are usually combined with halides of alkali metals, especially potassium.

[0145] In one embodiment, the additives are selected from antioxidants and color pigments.

[0146] About the structure The structure comprises at least two layers as defined above: an inner layer (I) and an outer layer (II).

[0147] In one embodiment, the structure consists of two layers (I) and (II) as defined above.

[0148] In another embodiment, depending on the formulation of the polyolefin or blend of the thermoplastic elastomer with the polyolefin, a tie layer as defined above may be required to provide adhesion between the inner layer (I) and the outer layer (II).

[0149] In that case, the structure comprises, from the outside to the inside, the following layers: (II) / / combination / / (I).

[0150] In one embodiment, whatever the structure, the thickness of the outer layer comprises 5-30% of the total thickness of the structure.

[0151] In another embodiment, the thickness of the inner layer accounts for at least 70% of the total thickness, in particular for 70-95% of the total thickness.

[0152] In yet another embodiment, the thickness of the outer layer constitutes 5-30% of the total thickness of the structure, and the inner layer constitutes at least 70% of the total thickness, in particular 70-95% of the total thickness.

[0153] The at least one thermoplastic polymer P1 of the inner layer (I) is advantageously chosen from non-functionalized polyolefins, functionalized polyolefins, and blends thereof.

[0154] In one embodiment, the at least one thermoplastic polymer P1 of the inner layer (I) is a non-functionalized polyolefin, said polyolefin being chosen from polyethylene and polypropylene.

[0155] In another embodiment, the at least one thermoplastic polymer P1 of the inner layer (I) is a non-functionalized polyolefin, which is a polyethylene.

[0156] In yet another embodiment, the at least one thermoplastic polymer P1 of the inner layer (I) is a non-functionalized polyolefin, which is polypropylene.

[0157] In a first alternative form in which the structure comprises two or three layers, the structure comprises a layer (II) having an average number of carbon atoms per nitrogen atom of C4 to C 15 The present invention also includes compositions based on semi-crystalline aliphatic polyamides,

[0158] In one embodiment of this first alternative form, layer (I) of the structure is made of polypropylene, in particular stabilized by a compound chosen from heat stabilizers and metal deactivators, or a mixture thereof.

[0159] In a second alternative form in which the structure comprises two or three layers, the structure comprises a layer (II) comprising a composition based on a semicrystalline aliphatic polyamide with an average number of carbon atoms per nitrogen atom ranging from C4 to C9, and layer (I) of the structure is made of polypropylene, which is stabilized in particular by a compound chosen from a heat stabilizer and a metal deactivator, or a mixture thereof.

[0160] In this second alternative form, the auxiliary polyamide is advantageously selected from PA6, PA66, PA410, PA412, PA610 and PA612, in particular from PA610 and PA612.

[0161] In this second alternative, the structure resides within the battery pack of the electric vehicle.

[0162] In this second alternative, the structure may also be internal and / or external to the battery pack of the stationary energy storage system.

[0163] In a third alternative form in which the structure comprises two or three layers, the structure comprises a layer (II) having an average number of carbon atoms per nitrogen atom of C 10 ~C 15 and layer (I) of the structure is made of polypropylene, which is stabilized in particular by a compound chosen from heat stabilizers and metal deactivators, or a mixture thereof.

[0164] In this third alternative form, the polyamide is advantageously selected from PA614, PA618, PA1010, PA1012, PA1014, PA1018, PA1210, PA1212, PA1214, PA1218, PA11 or PA12, in particular from PA11 and PA12.

[0165] In this third alternative, the structure is internal and / or external to the battery pack of the electric vehicle.

[0166] In this third alternative, the structure may also be internal and / or external to the battery pack of the stationary energy storage system.

[0167] In all embodiments and various alternative forms of construction, it is advantageous if the polyolefin of the inner layer and the polyolefin of the outer layer are the same.

[0168] In all embodiments and various alternative forms of construction, it is advantageous for the polyolefin of the inner layer to be different from the polyolefin of the outer layer.

[0169] According to another aspect, the invention relates to the use of a flame-retardant tubular structure as defined above for cooling a battery of an electric vehicle or a battery of a stationary energy storage system.

[0170] All of the embodiments described above for the polyamides, polyolefins, flame retardants and structures are useful for this use.

[0171] The invention will now be illustrated by means of non-limiting examples of the invention.

[0172] Working Example The compositions in Table 1 were produced by melt blending polyamide granules with flame retardants, polyolefins, and optionally plasticizers and additives. The % values ​​are given as weight percent based on the total weight of the composition. The blending was carried out by compounding using a co-rotating twin screw extruder (diameter 40 mm, flat temperature profile (T°) at 250° C.). The screw speed is 225 rpm and the throughput is 55 kg / h.

[0173] The polyamide(s), polyolefin(s), optionally plasticizers and additives are introduced during the compounding process via the main hopper. Flame retardants are added to the molten polymer in the middle of the screw via a side feeder. If a plasticizer is present, it is also introduced into the molten polymer via a pump.

[0174] These compositions are then extruded and coextruded into 8x1 mm tubular shapes.

[0175] MLT (8x1 mm multi-layer tubes) or mono-layer tubes (8x1 mm mono-layer tubes) are produced on a conventional multi-layer tube extrusion line as described in EP 2 098 580 or, in the case of mono-layers, on a conventional Maillefer 60 mono-layer line and their mechanical properties and fire resistance are investigated according to the following criteria:

[0176] The temperature profile used for non-flame retardant and flame retardant PA is as follows (from the granule feed zone to the end of the screw): 210 / 220 / 220 / 220. The temperature (melt) at the die exit is around 220°C. The polyolefins were extruded with the following temperature profile: 160 / 210 / 220 / 220. The temperature of the melt at the die exit is around 220°C. The outer diameter of the mandrel is 12 mm and the inner diameter of the die is 18 mm. The tubes are obtained with a hole and their inner diameter is between 8.5 mm and 9.2 mm.

[0177] The monolayer and multilayer tubes produced by the above extrusions were then evaluated on several criteria: ·Flexibility VW-40℃ shock Cool mixed aging: The tube was filled with an aqueous glycol solution (Havoline solution (50% by weight), diluted with water) and thermally aged in an oven at 110°C.

[0178] The measurement results and methods are shown in Tables 2 to 4 below.

[0179] The construction according to the invention and the comparative construction were tested outside the tube by a test normally performed on flame propagation (called UL94 according to the standard IEC 60695-11-10).

[0180] The UL 94 test (which generally applies to bars of one product) is carried out here on a single-wall structure (single-wall tube) or on a multi-layer structure, in particular a three-wall tube, in which the flame is in contact with only the outer layer of the tube, the dimensions of the layers from the outer layer to the inner layer being as follows: 0.15mm / / 0.10mm / / 0.7mm, or 0.350mm / / 0.10mm / / 0.55mm.

[0181] TIFF2025507994000003.tif96170

[0182] TIFF2025507994000004.tif93170

[0183] TIFF2025507994000005.tif133170

[0184] TIFF2025507994000006.tif114170

[0185] (1) 8×1 mm single-layer tube and 8×1 mm multi-layer tube, the three layers are distributed as follows from the outer layer to the inner layer: 0.15mm / / 0.10mm / / 0.75mm, and 0.35mm / / 0.10mm / / 0.55mm. The tubes in the two layers are distributed from the outer layer to the inner layer as follows: 0.15mm / / 0.85mm. (2) Flexural modulus according to ISO 178:2010, determined at 23 °C and 50% relative humidity (RH) (expressed in MPa). (3) Impact at -40°C (% is breakage) according to VW TL-52435 §6.5, PV 3905 standard (4) Ageing resistance in air at 110°C, half-life (h) (corresponding to the point of 50% reduction in elongation according to ISO 527-1A). This ageing is fully representative of the application of ageing in air (outside the tube) / fluid (inside the tube): A = half-life > 1500 h; B = half-life >500h and <1500h; C=half-life <500h. (5) UL 94 rating according to IEC 60695-11-10 Orevac® IM 800: HDPE modified with maleic anhydride (SK functional polymer) Maleic anhydride grafted LDPE binder: Admer GT7 (Mitsui) ·HDPE*:Lupolen GX5038(LyondellBasell) HDPE-g-MAH**: A blend (as a dry blend) of 93% by weight of Lupolen GX5038 (LyondellBasell) and 7% by weight of Orevac OE25 (SK functional polymer). The addition of Orevac OE25 (LLDPE highly grafted with maleic anhydride) makes it possible to obtain HDPE-g-MAH for adhering to the polyamide layer.

Claims

1. A flame-retardant multilayer tubular structure for cooling the battery of an electric vehicle or the battery of a stationary energy storage system, the structure comprising at least two layers, namely an inner layer (I) and an outer layer (II), The inner layer (I) contains at least 40% by weight of at least one thermoplastic polymer P1 selected from polyolefins and thermoplastic elastomers, and up to 5% by weight of a compound selected from heat stabilizers and metal deactivators or a mixture thereof. - The outer layer (II) contains a composition based on at least one major polyamide, and the composition is expressed by weight, based on the total weight of layer (II). a) At least one polyamide in at least 50% by weight, b) At least one flame retardant in an amount of 15 to 38% by weight, c) Polyolefin in 4 to 20% by weight, especially 4 to 15% by weight, d) At least one plasticizer in 0 to 10% by weight, particularly 0.1 to 10% by weight, e) At least one additive in 0 to 5% by weight, particularly 0.1 to 5% by weight, It contains, and the sum of a) + b) + c) + d) + e) ​​is equal to 100%. Flame retardant multilayer tubular structure.

2. The flame-retardant multilayer tubular structure according to claim 1, characterized in that the polyamide is selected from semicrystalline aliphatic polyamides having an average number of carbon atoms per nitrogen atom of 4 to 15, and semicrystalline semi-aromatic polyamides (PPA).

3. The flame-retardant multilayer tubular structure according to claim 2, characterized in that the semicrystalline aliphatic polyamide has an average number of carbon atoms per nitrogen atom of 4 to 9.

4. The flame-retardant multilayer tubular structure according to claim 3, characterized in that the semicrystalline aliphatic polyamide is selected from PA6, PA66, PA410, PA412, PA610, and PA612, particularly from PA610 and PA612.

5. The flame-retardant multilayer tubular structure according to claim 3, characterized in that it is located inside the battery pack of the electric vehicle.

6. The flame-retardant multilayer tubular structure according to claim 2, characterized in that the semi-crystalline aliphatic polyamide has an average number of carbon atoms per nitrogen atom of 10 to 15.

7. The flame-retardant multilayer tubular structure according to claim 6, characterized in that the semicrystalline aliphatic polyamide is selected from PA614, PA618, PA1010, PA1012, PA1014, PA1018, PA1210, PA1212, PA1214, PA1218, PA11, and PA12, particularly from PA11 and PA12.

8. The flame-retardant multilayer tubular structure according to claim 6, characterized in that it exists inside and / or outside the battery pack of the electric vehicle.

9. The flame-retardant multilayer tubular structure according to claim 3, characterized in that it exists inside and / or outside the battery pack of a stationary energy storage system.

10. The flame-retardant multilayer tubular structure according to claim 2, characterized in that the polyamide is a semi-crystalline semi-aromatic polyamide (PPA).

11. The flame-retardant multilayer tubular structure according to claim 10, characterized in that the semi-crystalline semi-aromatic polyamide is selected from 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, particularly from PA11 / 10T and PA11 / 12T.

12. The flame-retardant multilayer tubular structure according to claim 10, characterized in that it exists inside and / or outside the battery pack of the electric vehicle, or inside and / or outside the battery pack of a stationary energy storage system.

13. The flame-retardant multilayer tubular structure according to claim 1, characterized in that the polyolefin P1 of the inner layer (I) is selected from non-functional polyolefins, functional polyolefins, and blends thereof.

14. The flame-retardant multilayer tubular structure according to claim 13, characterized in that the polyolefin P1 of the inner layer (I) is a non-functional polyolefin, and the tubular structure includes a binding layer (III) located between the inner layer (I) and the outer layer (II).

15. The flame-retardant multilayer tubular structure according to claim 1, characterized in that the polyolefin P1 of the inner layer (I) is a non-functional polyolefin selected from polyethylene and polypropylene.

16. The flame-retardant multilayer tubular structure according to claim 1, characterized in that the thickness of the outer layer (II) is 5 to 30% of the total thickness of the structure.

17. The flame-retardant multilayer tubular structure according to claim 1, characterized in that the thickness of the inner layer (I) is at least 70% of the total thickness of the structure.

18. The flame-retardant multilayer tubular structure according to claim 14, characterized in that the thickness of the outer layer (II) is 5 to 30% of the total thickness of the structure, and the thickness of the inner layer (I) is at least 70% of the total thickness of the structure.

19. Use of the flame-retardant multilayer tubular structure according to claim 1 for cooling an electric vehicle battery or a battery in a stationary energy storage system.