Fireproof multilayer tubular structure for cooling electric vehicle battery or stationary energy storage system battery

Abstract

The invention relates to a fireproof multilayer tubular structure for cooling an electric vehicle battery or a stationary energy storage system battery, comprising at least two layers: an inner layer (I) comprising at least 40% of at least one thermoplastic polymer P1 selected from the group consisting of polyolefins and thermoplastic elastomers, and up to 5% by weight of a compound selected from the group consisting of thermal stabilizers and metal deactivators or mixtures thereof; and an outer layer (II) comprising a composition based on at least one main polymer comprising: a) at least 50% by weight of at least one polyamide, b) from 15% to 38% by weight of at least one fire retardant; c) from 4% to 20% by weight, in particular from 4% to 15% by weight, of a polyolefin; d) from 0% to 10% by weight, in particular from 0.1% to 10% by weight, of at least one plasticizer, and e) from 0% to 5% by weight, in particular from 0.1% to 5% by weight, of at least one additive, the sum of a) + b) + c) + d) + e) being equal to 100% by weight.

Description

Technical Field

[0001] The present invention relates to a flame retardant multilayer tubular structure for cooling batteries of electric vehicles or stationary energy storage systems. Background Art

[0002] One of the desired goals, in particular in the field of motor vehicles, is to come up with vehicles that pollute less and less. Therefore, electric or hybrid vehicles containing batteries aim to gradually replace thermal vehicles such as gasoline or diesel vehicles.

[0003] In fact, it turns out that the battery is a relatively complex component of a vehicle. Depending on the location of the battery in the vehicle, it may be necessary to protect it from impacts and the external environment, which may be at extreme temperatures and variable humidity. It must also be protected from any risk of fire.

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

[0005] Another desired goal, especially in stationary energy storage systems, is to have available systems which make it possible to produce renewable energy sources smoothly, to operate electric vehicles or very simply to reinforce the power grid.

[0006] Stationary energy storage therefore becomes strategic as it helps ensure a balance between electricity production and consumption. Energy is stored during off-peak or high production periods and released later in situations of high demand or low production.

[0007] Electric or hybrid motor vehicles or stationary energy storage systems therefore require a device for cooling the battery or the system, which device generally consists of a multilayer tubular line.

[0008] In order to protect the integrity of the vehicle or the system, the tubing must provide flame retardancy. These tubings fall into two categories, especially for electric vehicles: tubing inside the battery pack and tubing outside the battery pack. The specifications for tubing outside the battery pack are more stringent and also require resistance to zinc chloride (under-the-hood environment) and cold shock.

[0009] These battery cooling lines or stationary energy storage system cooling lines generally transport coolants, and long-chain polyamides are very suitable for these lines. They show good service life when in contact with coolants (90-110°C), while providing:

[0010] - flexibility of the structure, which facilitates installation on vehicles,

[0011] -Structure is resistant to the harsh environment under the hood.

[0012] It is also possible to impart fire resistance to polyamides by adding flame retardant fillers using a compounding route. However, this fire protection technology has not been able to provide the required primary properties for battery or stationary energy storage system cooling applications, since polyamides such as these are brittle and the impact strength of the tubular lines so formed is therefore insufficient.

[0013] This was achieved by developing a multi-layer solution, thus being able to combine all the above mentioned properties and meet the complex specifications of the application. Summary of the invention

[0014] The present invention therefore relates to a flame retardant multilayer tubular structure for an electric vehicle battery or a stationary energy storage system battery, comprising at least two layers:

[0015] an inner layer (I) comprising at least 40% by weight, relative to the total weight of said layer (I), of at least one thermoplastic polymer P1 chosen from polyolefins, thermoplastic elastomers and blends of these; and at most 5% by weight of a compound chosen from thermal stabilizers and metal deactivators or mixtures of these,

[0016] an outer layer (II) comprising a composition based on at least one main polyamide, said composition comprising by weight, relative to the total weight of said layer (II):

[0017] a) at least 50% of at least one polyamide,

[0018] b) from 15% to 38% of at least one flame retardant,

[0019] c) from 4 to 20%, in particular from 4 to 15%, of polyolefins,

[0020] d) from 0 to 10% by weight, in particular from 0.1 to 10% by weight, of at least one plasticizer,

[0021] e) from 0% to 5%, in particular from 0.1% to 5%, of at least one additive,

[0022] The sum a)+b)+c)+d)+e) equals 100%.

[0023] The present invention therefore relates to a flame retardant multilayer tubular structure for cooling an electric vehicle battery or a stationary energy storage system battery, comprising at least two layers:

[0024] an inner layer (I) comprising at least 40% by weight, relative to the total weight of said layer (I), of at least one thermoplastic polymer P1 chosen from polyolefins, thermoplastic elastomers and blends of these,

[0025] an outer layer (II) comprising a composition based on at least one main polyamide, said composition comprising by weight, relative to the total weight of said layer (II):

[0026] a) at least 50% of at least one polyamide,

[0027] b) from 15% to 38% of at least one flame retardant,

[0028] c) from 4 to 20%, in particular from 4 to 15%, of polyolefins,

[0029] d) from 0 to 10% by weight, in particular from 0.1 to 10% by weight, of at least one plasticizer,

[0030] e) from 0% to 5%, in particular from 0.1% to 5%, of at least one additive,

[0031] The sum a)+b)+c)+d)+e) equals 100%.

[0032] According to one embodiment, the present invention relates to a flame retardant multilayer tubular structure for cooling an electric vehicle battery or a stationary energy storage system battery, comprising at least two layers:

[0033] an inner layer (I) comprising at least 20% by weight of a polyolefin, optionally from 0% to 80% by weight of an elastomer, and optionally from 0% to 5% by weight of a heat stabilizer, relative to the total weight of said layer (I),

[0034] an outer layer (II) comprising a composition based on at least one main polyamide, said composition comprising by weight, relative to the total weight of said layer (II):

[0035] a) at least 50% by weight of at least one polyamide,

[0036] b) from 15 to 38% by weight of at least one flame retardant,

[0037] c) from 4 to 20% by weight, in particular from 4 to 15% by weight, of polyolefins,

[0038] d) from 0 to 10% by weight, in particular from 0.1 to 10% by weight, of at least one plasticizer,

[0039] e) from 0 to 5% by weight, in particular from 0.1 to 5% by weight, of at least one additive,

[0040] The sum a)+b)+c)+d)+e) equals 100%. The inventors have thus surprisingly found that a multilayer structure comprising at least two layers, the inner layer of which consists of an optionally stabilized polyolefin and the outer layer of which is based on a polyamide comprising a flame retardant, makes it possible to form a structure combining fire resistance with good service life in prolonged contact with coolants, flexibility, zinc chloride resistance and good burst strength, which are essential for applications in cooling batteries for electric vehicles or batteries for stationary energy storage systems.

[0041] In one embodiment, the inner layer (I) comprises at least 40% by weight, in particular at least 50% by weight, especially at least 60% by weight, relative to the total weight of the layer (I), of at least one thermoplastic polymer P1 chosen from polyolefins, thermoplastic elastomers and blends of these, and up to 5% by weight of a compound chosen from heat stabilizers and metal deactivators or mixtures of these.

[0042] In one embodiment, the inner layer (I) comprises at least 40% by weight, in particular at least 50% by weight, especially at least 60% by weight, of at least one polyolefin, relative to the total weight of the layer (I).

[0043] In one embodiment, the inner layer (I) comprises up to 5 wt. % of heat stabilizer relative to the total weight of the layer (I), that is to say from 0 wt. % to 5 wt. % of heat stabilizer.

[0044] The expression "multilayer tubular structure" is understood to mean a tubular structure or a pipe structure which is cylindrical and circular in cross section.

[0045] The term "battery" is understood to mean a storage battery, also called a "battery".

[0046] The term "vehicle" is understood to mean a car, a truck, a train or an airplane, in particular a car.

[0047] The expression “stationary energy storage system” is to be understood as meaning, for example, the storage of electricity generated from renewable sources, increasing the stability of the power grid or supporting the self-use of electricity by individuals or businesses, which is achieved by mechanical storage (e.g. pumping stations, compressed air or inertial storage), chemical storage or electrochemical storage methods.

[0048] The term "flame retardant" means that the flame retardancy result of the tubular structure is V0 in the UL94 test (IEC 60695-11-10) at 0.8 mm.

[0049] The UL94 test is generally applicable to rods of a single product, here performed on a single-layer structure (single-layer tube) or a multi-layer structure, in particular a three-layer tube, wherein the flame contacts only the outer layer of the tube, the three-layer tube exhibiting the following layer dimensions: from outer layer to inner layer: 0.15 mm / / 0.10 mm / / 0.75 mm or 0.350 mm / / 0.10 mm / / 0.55 mm.

[0050] About polyamide

[0051] The nomenclature used to define polyamides is described in standard ISO 1874-1:2011, "Plastics—Polyamide (PA) molding and extrusion materials—Part 1: Designation", in particular on page 3 (Tables 1 and 2), and is familiar to those skilled in the art.

[0052] According to this patent application, the term "polyamide", also referred to as "PA", refers to:

[0053] - homopolymers,

[0054] - copolymers or copolyamides based on different amide units, such as copolyamide 6 / 12 having amide units derived from lactam-6 and lactam-12,

[0055] - Polyamide alloys, provided that polyamide is the main component.

[0056] There is also a class of generalized copolyamides which, although not preferred, nevertheless fall within the scope of the invention. These copolyamides contain not only amide units (which are the main ones, so in fact they are considered as copolyamides in the generalized sense), but also units of a non-amide nature, such as ether units. The best-known examples are PEBA or polyether block amides, and their copolyamide-ester-ether, copolyamide-ether or copolyamide-ester variants. Among these, mention may be made of PEBA-12, in which the polyamide units are identical to those of PA12, and PEBA-6.12, in which the polyamide units are identical to those of PA6.12.

[0057] The polyamide may be an amorphous or a semi-crystalline polyamide.

[0058] Within the meaning of the present invention, an amorphous polyamide is a polyamide which exhibits only a glass transition temperature (without a melting point (Tm)), or is an extremely microcrystalline polyamide having a glass transition temperature and a melting point such that the crystallization enthalpy during the cooling stage at a rate of 20 K / min, measured in accordance with standard ISO 11357-3:2013, is less than 30 J / g, in particular less than 20 J / g, preferably less than 15 J / g.

[0059] Within the meaning of the present invention, a semi-crystalline polyamide is a polyamide which exhibits a glass transition temperature and a melting point (Tm) as determined according to Standard ISO 6721-11:2019, by dynamic mechanical analysis (DMA), and a crystallization enthalpy as determined according to Standard ISO 11357-3:2013, as well as a cooling stage at a rate of 20 K / min in DSC of greater than 30 J / g, preferably greater than 35 J / g.

[0060] In a first form, the polyamide is obtainable by the polycondensation of at least one aminocarboxylic acid comprising from 6 to 18 carbon atoms, preferably from 9 to 18 carbon atoms, more preferably from 10 to 18 carbon atoms, still more preferably from 10 to 12 carbon atoms. Thus, it can 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.

[0061] Preferably, it is obtained by polycondensation of a single aminocarboxylic acid.

[0062] In a second alternative form, the polyamide is obtainable by polycondensation of at least one lactam comprising from 6 to 18 carbon atoms, preferably from 9 to 18, more preferably from 10 to 18 and even more preferably from 10 to 12 carbon atoms.

[0063] Preferably, it is obtained by polycondensation of a single lactam.

[0064] In a third alternative form, the polyamide is obtainable by polycondensation of at least one diamine X, which may be aliphatic, cycloaliphatic or aromatic, in particular aliphatic, containing 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 at least one dicarboxylic acid Y, which may be aliphatic, cycloaliphatic or aromatic, in particular aliphatic, containing 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, to form repeating units XY.

[0065] The aliphatic diamine used is an aliphatic diamine exhibiting a linear main chain comprising at least 4 carbon atoms.

[0066] If appropriate, this linear backbone may contain one or more methyl and / or ethyl substituents; in this latter configuration, the term "branched aliphatic diamine" is used. In the case where the backbone does not contain any substituents, the aliphatic diamine is referred to as a "linear aliphatic diamine".

[0067] The aliphatic diamine used to obtain the repeating unit XY comprises 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, whether or not it comprises methyl and / or ethyl substituents in its main chain.

[0068] When the diamine is a linear aliphatic diamine, it corresponds to the formula H2N-(CH2) x -NH2, and can be chosen, for example, from butanediamine, pentanediamine, hexanediamine, heptanediamine, octanediamine, nonanediamine, decanediamine, undecanediamine, dodecanediamine, tridecanediamine, tetradecanediamine, hexadecanediamine, octadecanediamine and octadecenediamine. The linear aliphatic diamines just mentioned can all be biobased within the meaning of standard ASTM D6866.

[0069] 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.

[0070] The alicyclic diamine used may be selected from 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, generally referred to as BMACM or MACM (and hereinafter indicated as B); bis(p-aminocyclohexyl)methane, generally referred to as PACM (and hereinafter indicated as P), in particular Isopropylidene di(cyclohexylamine), generally referred to as PACP; isophorone diamine (hereinafter referred to as IPD); 2,6-bis(aminomethyl)norbornane, generally referred to as BAMN; and bis(aminomethyl)cyclohexane (BAC), particularly 1,3-BAC or particularly 1,4-BAC.

[0071] Advantageously, it is chosen from bis(3-methyl-4-aminocyclohexyl)methane or 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane, generally known as BMACM or MACM (and hereinafter represented by B); bis(p-aminocyclohexyl)methane, generally known as PACM (and hereinafter represented by P); and bis(aminomethyl)cyclohexane (BAC), in particular 1,3-BAC or in particular 1,4-BAC.

[0072] A non-exhaustive list of these cycloaliphatic diamines is found in the publication “Cycloaliphatic Amines” (Encyclopedia of Chemical Technology, Kirk-Othmer, 4th edition (1992), pages 386-405).

[0073] The aromatic diamine may be selected from 1,3-phenylenediamine and 1,4-phenylenediamine.

[0074] The dicarboxylic acid may be selected from linear or branched aliphatic dicarboxylic acids.

[0075] When the dicarboxylic acid is aliphatic and linear, it may be selected from succinic acid (4), glutaric acid (5), adipic acid (6), pimelic acid (7), suberic acid (8), azelaic acid (9), decanedioic acid (10), undecanedioic acid (11), dodecanedioic acid (12), brassic acid (13), tetradecanedioic acid (14), hexadecanedioic acid (16), octadecanedioic acid (18), octadecenedioic acid (18), eicosanedioic acid (20), docosanedioic acid (22) and a fatty acid dimer containing 36 carbons.

[0076] The fatty acid dimers mentioned above are dimerized fatty acids obtained by oligomerization or polymerization of unsaturated monobasic fatty acids having long-chain hydrocarbons, such as linoleic acid and oleic acid, as described in particular in document EP 0 471566.

[0077] When the dicarboxylic acid is alicyclic, it may comprise the following carbon backbone: norbornylmethane, cyclohexane, cyclohexylmethane, dicyclohexylmethane, dicyclohexylpropane, di(methylcyclohexyl) or di(methylcyclohexyl)propane.

[0078] When the dicarboxylic acid is aromatic, it is advantageously chosen from terephthalic acid (denoted by T), isophthalic acid (denoted by I) and 2,6-naphthalene dicarboxylic acid (denoted by N) or mixtures thereof; in particular, it is chosen from terephthalic acid (denoted by T), isophthalic acid (denoted by I) or mixtures thereof.

[0079] In a fourth alternative form, the polyamide is obtained by blending at least two of these three alternatives.

[0080] Advantageously, said polyamide is a semi-crystalline polyamide.

[0081] In a first embodiment, the polyamide is selected from the group consisting of polyamides having an average number of carbon atoms per nitrogen atom of C4 to C 15 Semi-crystalline aliphatic polyamide and semi-crystalline semi-aromatic polyamide (PPA).

[0082] In the case of homopolyamides of the XY type, X represents a unit obtained from a diamine and Y represents a unit obtained from a dicarboxylic acid, the number of carbon atoms per nitrogen atom being the average of the number of carbon atoms present in the units resulting from the diamine X and in the units resulting from the dicarboxylic acid Y. Thus, PA6.12 is a PA having 9 carbon atoms per nitrogen atom, in other words a C9 PA. PA6.13 is a C 9.5 PA.

[0083] In the case of copolyamides, the number of carbon atoms per nitrogen atom is calculated according to the same principle. The calculation is carried out on the basis of the molar proportions of the various amide units.

[0084] The semiaromatic polyamide PPA, optionally modified with urea units, is chosen in particular from PA MXD6, PAMXD10 or from a semiaromatic polyamide of formula X / YAr as described in EP 1 505 099, in particular from a semiaromatic polyamide of formula A / ZT, in which A is chosen from units obtained from amino acids as defined above, units obtained from lactams as defined above and units corresponding to the formula (Ca diamine)(Cb dicarboxylic acid), in which a represents the number of carbon atoms of the diamine and the Ca diamine is as defined above for the diamine X, and b represents the number of carbon atoms of the dicarboxylic acid and the Cb diacid is as defined above for the dicarboxylic acid Y;

[0085] ZT represents a unit obtained by polycondensation of an aliphatic or alicyclic Cx diamine (as defined above for the diamine X) with terephthalic acid.

[0086] A / ZT particularly represents a polyamide of the formula A / 6T, A / 9T, A / 10T or A / 11T, A being as defined above, and particularly the polyamide being selected from PA6 / 6T, PA66 / 6T, PA61 / 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, PAMP MDT / 6T, PAMXDT / 10T, PAMPMDT / 10T, PABACT / 10T, PABACT / 6T, PABACT / 10T / 6T or PA11 / BACT / 10T,

[0087] In particular, polyamides are selected from the group consisting of 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.

[0088] T corresponds to terephthalic acid, MXD corresponds to meta-xylylenediamine, MPMD corresponds to methylpentamethylenediamine, and BAC corresponds to bis(aminomethyl)cyclohexane.

[0089] In a first alternative form of this first embodiment, the semicrystalline aliphatic polyamide has an average number of carbon atoms per nitrogen atom of from C4 to C9.

[0090] Advantageously, the semicrystalline aliphatic polyamide is chosen from PA6, PA66, PA410, PA412, PA610 and PA612, in particular PA610 and PA612.

[0091] The polyamide of this first alternative form of this first embodiment can be used for the outer layer (II) of the tubular structure of the invention, which is present inside the battery of the electric vehicle.

[0092] The polyamide of this first alternative form of this first embodiment can also be used for the outer layer (II) of the tubular structure of the invention, which is present inside and / or outside a battery of a stationary energy storage system.

[0093] In a second alternative form of this first embodiment, the semicrystalline aliphatic polyamide exhibits C 10 To C 15 The average number of carbon atoms per nitrogen atom.

[0094] Advantageously, the semicrystalline aliphatic polyamide is chosen from PA614, PA618, PA1010, PA1012, PA1014, PA1018, PA1210, PA1212, PA1214, PA1218, PA11 or PA12, in particular PA11 and PA12.

[0095] The polyamide of this second alternative form of this first embodiment can be used for the outer layer (II) of the tubular structure of the invention, present inside and / or outside the battery pack of the electric vehicle.

[0096] The polyamide of this second alternative form of the first embodiment can also be used for the outer layer (II) of the tubular structure of the invention, which is present inside and / or outside a battery of a stationary energy storage system.

[0097] In a second embodiment, the polyamide is a semi-crystalline semi-aromatic polyamide (PPA).

[0098] Advantageously, the semicrystalline semiaromatic polyamide in this second embodiment is chosen 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.

[0099] More advantageously, the semicrystalline semiaromatic polyamide in this second embodiment is chosen 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 PA11 / 10T and PA11 / 12T.

[0100] The polyamide of this second embodiment can be used for the outer layer (II) of the tubular structure of the invention, which is present inside and / or outside the battery pack of the electric vehicle or the battery pack of a stationary energy storage system.

[0101] About thermoplastic polymer P1:

[0102] Polyolefins:

[0103] According to one embodiment, said layer (I) may comprise at least one polyolefin.

[0104] In one embodiment, the polyolefin of the inner layer (I) may be a non-functionalized polyolefin selected from polyethylene and polypropylene. It may in particular be a high density polyethylene (HDPE).

[0105] According to one embodiment, the inner layer (I) comprises at least 20% by weight of polyolefin, optionally from 0% to 80% by weight of elastomer and optionally from 0% to 5% by weight of heat stabilizer relative to the total weight of layer (I).

[0106] The polyolefins may be functionalized or non-functionalized, or blends of these.

[0107] For simplicity, the polyolefin is represented as (B), and the functionalized polyolefin (B1) and the non-functionalized polyolefin (B2) are described below.

[0108] The non-functionalized polyolefin (B2) is generally a homopolymer or copolymer of an α-olefin or a diene such as ethylene, propylene, 1-butene, 1-octene or butadiene. As examples, mention may be made of:

[0109] - polyethylene homopolymers and copolymers, in particular LDPE, HDPE, LLDPE (linear low-density polyethylene), VLDPE (very low-density polyethylene), PE-RT (or PE-RT) and metallocene polyethylene,

[0110] - propylene homopolymer or copolymer,

[0111] - ethylene / α-olefins, such as ethylene / propylene, copolymers, EPR (abbreviation for ethylene-propylene rubber) and ethylene / propylene / diene (EPDM),

[0112] - copolymers of ethylene and at least one product selected from the group consisting of salts or esters of unsaturated carboxylic acids, such as alkyl (meth)acrylates (e.g. methyl acrylate), or vinyl esters of saturated carboxylic acids, such as vinyl acetate (EVA), the proportion of comonomers being up to 40% by weight.

[0113] The functionalized polyolefin (B1) may be a polymer of an α-olefin having a reactive unit (functionality / group); such a reactive unit is an acid, anhydride or epoxy functional group. By way of example, the aforementioned polyolefin (B2) may be grafted or copolymerized or terpolymerized with an unsaturated epoxide, such as glycidyl (meth)acrylate, or with a carboxylic acid or a corresponding salt or ester, such as (meth)acrylic acid (the latter may be completely or partially neutralized with a metal such as zinc, etc.), or with a carboxylic anhydride such as maleic anhydride. The functionalized polyolefin is, for example, a PE / EPR blend, the weight ratio of which may vary within wide limits, for example between 40 / 60 and 90 / 10, the blend being co-grafted with an anhydride, in particular maleic anhydride, the degree of grafting being, for example, from 0.01% to 5% by weight.

[0114] The functionalized polyolefin (B1) can be chosen from the following (co)polymers grafted with maleic anhydride or glycidyl methacrylate, wherein the degree of grafting is, for example, from 0.01% to 5% by weight:

[0115] - PE, PP, copolymers of ethylene with propylene, butene, hexene or octene, for example from 35 to 80% by weight of ethylene;

[0116] - ethylene / α-olefins, such as ethylene / propylene, copolymers, EPR (abbreviation for ethylene-propylene rubber) and ethylene / propylene / diene (EPDM);

[0117] - styrene / ethylene-butylene / styrene (SEBS), styrene / butadiene / styrene (SBS), styrene / isoprene / styrene (SIS) or styrene / ethylene-propylene / styrene (SEPS) block copolymers;

[0118] - copolymers of ethylene and vinyl acetate (EVA), containing up to 40% by weight of vinyl acetate;

[0119] - copolymers of ethylene and alkyl (meth)acrylates containing up to 40% by weight of alkyl (meth)acrylates;

[0120] - Copolymers of ethylene with vinyl acetate (EVA) and alkyl (meth)acrylates containing up to 40% by weight of comonomers.

[0121] Functionalized polyolefins (B1) can also be selected from ethylene / propylene copolymers, mainly propylene, grafted with maleic anhydride and then condensed with monoaminated polyamides (or monoaminated polyamide oligomers) (products described in EP-A-0 342 066).

[0122] The functionalized polyolefin (B1) may also be a copolymer or terpolymer of at least the following units: (1) ethylene, (2) an alkyl (meth)acrylate or a saturated carboxylic acid vinyl ester and (3) an anhydride, such as maleic anhydride, or a (meth)acrylic acid or an epoxide, such as glycidyl (meth)acrylate.

[0123] As examples of functionalized polyolefins of the latter type, mention may be made of the following copolymers, in which ethylene preferably represents at least 60% by weight, and in which the termonomer (functional group) represents, for example, from 0.1% to 10% by weight of the copolymer:

[0124] - ethylene / alkyl (meth)acrylate / (meth)acrylic acid or maleic anhydride or glycidyl methacrylate copolymers;

[0125] - Ethylene / vinyl acetate / maleic anhydride or glycidyl methacrylate copolymer

[0126] - Ethylene / vinyl acetate or alkyl (meth)acrylate / (meth)acrylic acid or maleic anhydride or glycidyl methacrylate copolymers.

[0127] In the foregoing copolymers, (meth)acrylic acid may be salified with Zn or Li.

[0128] The term "alkyl (meth)acrylate" in (B1) or (B2) means C1 to C8 alkyl methacrylate and C1 to C8 alkyl acrylate, and may be selected from methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, methyl methacrylate and ethyl methacrylate.

[0129] In addition, the above-mentioned polyolefin (B1) can also be cross-linked by any appropriate process or reagent (diepoxy, dibasic acid, peroxide, etc.); the term "functionalized polyolefin" also includes a mixture of the above-mentioned polyolefin and a difunctional reactant (such as dibasic acid, dianhydride, diepoxy, etc.) capable of reacting with these above-mentioned polyolefins, or a blend of at least two functionalized polyolefins capable of reacting together.

[0130] The above-mentioned copolymers (B1) and (B2) may be copolymerized randomly or in blocks, and may exhibit a linear or branched structure.

[0131] The molecular weight, MFI index and density of these polyolefins can also vary within a wide range, which will be appreciated by those skilled in the art. MFI is the abbreviation for melt flow index. It is measured according to standard ASTM 1238.

[0132] Advantageously, the non-functionalized polyolefin (B2) is chosen from polypropylene homopolymers or copolymers and any ethylene homopolymer or copolymer of ethylene and a comonomer of the higher alpha-olefin type (such as butene, hexene, octene or 4-methyl-1-pentene). For example, PP, high-density PE, medium-density PE, linear low-density PE, low-density PE or very low-density PE may be mentioned. These polyethylenes are known to those skilled in the art to be produced according to "free radical" processes, "Ziegler" type catalysis or more recently "metallocene" catalysis.

[0133] Advantageously, the functionalized polyolefin (B1) is chosen from any polymer comprising alpha-olefin units and units carrying reactive polar functional groups such as epoxy, carboxylic acid or carboxylic anhydride functional groups. Examples of such polymers include terpolymers of ethylene, alkyl acrylates, maleic anhydride or glycidyl methacrylate, such as Products (SKFunctional Polymer), or polyolefins grafted with maleic anhydride, such as Products of SK Functional Polymer, and terpolymers of ethylene, alkyl acrylates and (meth) acrylic acid. Mention may also be made of polypropylene homopolymers or copolymers grafted with carboxylic anhydride and then condensed with monoaminated polyamide or monoaminated polyamide oligomers.

[0134] In one embodiment, the polyolefin is cross-linked.

[0135] In another embodiment, the polyolefin is a mechanical blend of a thermoplastic olefin polymer having a polyethylene or polypropylene matrix and an elastomer, which is vulcanized, such as a vulcanized PP / EPDM blend.

[0136] Thermoplastic Elastomers:

[0137] According to one embodiment, said layer (I) may comprise at least one thermoplastic elastomer.

[0138] The thermoplastic elastomer is a block copolymer (ether-amide block copolymer: PEBA), ether-ester block copolymer, thermoplastic polyurethane: TPU, thermoplastic styrene elastomer).

[0139] Advantageously, said thermoplastic polymer P1 of the inner layer (I) is chosen from non-functionalized polyolefins, functionalized polyolefins and blends of these.

[0140] Advantageously, said at least one thermoplastic polymer P1 of the inner layer (I) is a non-functionalized polyolefin and said tubular structure comprises a tie layer (III) situated between said layer (I) and said layer (II).

[0141] 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. In particular, it may especially be a high-density polyethylene (HDPE).

[0142] According to one embodiment, the inner layer (I) comprises at least 20% by weight of polyolefin, optionally from 0% to 80% by weight of elastomer, and optionally from 0% to 5% by weight of heat stabilizer, relative to the total weight of layer (I).

[0143] The polyolefin may be as described above.

[0144] As regards the elastomer, it may in particular be a TPE (thermoplastic elastomer), ie a compound made from a hard thermoplastic material of the PP, PBT or PA type combined with a soft rubber material.

[0145] As examples of thermoplastic elastomers suitable for the present invention, mention may in particular be made of thermoplastic olefins (TPE-O), SBS, SEBS or SEPS styrene compounds (TPE-S), vulcanized PP / EPDM compounds (TPE-V), copolyester compounds (TPE-E), thermoplastic polyurethanes (TPE-U) and thermoplastic polyamides (TPE-A).

[0146] About Adhesives

[0147] The adhesive may be an adhesive composition as described in EP 2 098 580, that is to say, the adhesive composition comprises:

[0148] - at least one polyamide, denoted A, exhibiting a relative humidity, denoted C, between 4 and 8.5, advantageously between 4 and 7 A The average number of carbon atoms per nitrogen atom;

[0149] - at least one polyamide, denoted B, exhibiting a melting point greater than or equal to 180° C. and denoted C between 7 and 10, advantageously between 7.5 and 9.5 B The average number of carbon atoms per nitrogen atom;

[0150] - at least one polyamide denoted C, exhibiting between 9 and 18, advantageously between 10 and 18, denoted C C The average number of carbon atoms per nitrogen atom,

[0151] At least 50% by weight of the composition consists of one or more polyamides selected from polyamides A, B and C,

[0152] The weight-weighted average melting enthalpy of the polyamides in the composition is greater than 25 J / g (DSC),

[0153] The average carbon atoms per nitrogen atom of polyamides A, B and C also correspond to the following strict inequality: A <C B <C C .

[0154] For example, the adhesive may also be (but not limited to) a composition based on 50% copolyamide 6 / 12 (70 / 30 by weight) and 50% copolyamide 6 / 12 (30 / 70 by weight), a composition based on PP (polypropylene) grafted with maleic anhydride (from Mitsui, named Admer QF551A), a composition based on PA610 and PA6 and an organic stabilizer, a composition based on PA612, PA6 and an organic stabilizer, a composition based on PA610 (Mn is 30,000, as defined elsewhere) and PA12 and an organic stabilizer, a composition based on PA6, PA12 and a functionalized EPR Exxelor A composition of VA1801 (Exxon) and an organic stabilizer, or a composition based on PA610, PA6 and an ethylene / ethyl acrylate / anhydride type impact modifier in a weight ratio of 68.5 / 30 / 1.5 (MFI at 190°C under 2.16 kg is 6) and an organic stabilizer.

[0155] The adhesive may also be a functionalized polyolefin (such as polyethylene or polypropylene) copolymer whose functional comonomer is selected from acid, anhydride or epoxide groups.

[0156] The functional group is selected from compounds of carboxylic acids or anhydride derivatives of unsaturated carboxylic acids thereof.

[0157] Examples of unsaturated dicarboxylic anhydrides are in particular maleic anhydride, itaconic anhydride, citraconic anhydride or tetrahydrophthalic anhydride. Maleic anhydride is preferably used.

[0158] However, the functional comonomer may contain unsaturated epoxide type functional groups.

[0159] 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 cycloaliphatic glycidyl esters and ethers, such as 2-cyclohexen-1-yl glycidyl ether, cyclohexene-4,5-dicarboxylic acid diglycidyl ester, cyclohexene-4-carboxylic acid glycidyl ester, 2-methyl-5-norbornene-2-carboxylic acid glycidyl ester and endo-cis-bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid diglycidyl ester.

[0160] About flame retardants

[0161] It represents from 15% to 38% of the composition of the outer layer (II).

[0162] The flame retardant may be a halogen-free flame retardant such as described in US 2008 / 0274355, in particular a phosphorus-based flame retardant.

[0163] The flame retardant is in particular selected from metal salts of phosphinic acid, metal salts of diphosphoric acid, polymers containing at least one metal salt of phosphinic acid or polymers containing at least one metal salt of diphosphoric acid. The flame retardant may also be a mixture of the abovementioned flame retardants.

[0164] The flame retardant may also be selected from the group consisting of metal hypophosphites of the following formula (I) and metal diphosphites of the following formula (II):

[0165]

[0166] in

[0167] R1 and R2 independently represent a linear or branched C 1- C6 alkyl group or aryl group;

[0168] R3 represents a linear or branched C 1- C 10 Alkylene, C 6- C 10 Arylene, C 6- C 10 Alkyl arylene or C 6- C 10 Arylalkylene group,

[0169] M is a Mg, Ca, Al, Sb, Sn, Ge, Ti, Zn, Fe, Zr, Ce, Bi, Sr, Mn, Li, Na or K ion and / or a protonated amine base,

[0170] m represents an integer from 1 to 4,

[0171] n represents an integer from 1 to 4,

[0172] x represents an integer from 1 to 4,

[0173] n and m are chosen so that the salt is neutral, that is, it has no electrical charge.

[0174] Preferably, M represents a calcium, magnesium, aluminum or zinc ion.

[0175] Preferably, R1 and R2 independently of one another represent a methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, n-pentyl and / or phenyl group.

[0176] Preferably, R3 is a methylene, ethylene, n-propylene, isopropylene, n-butylene, tert-butylene, n-pentylene, n-octylene, n-dodecylene; a phenylene, a naphthylene; a methylphenylene, an ethylphenylene, a tert-butylphenylene, a methylnaphthylene, an ethylnaphthylene, a tert-butylnaphthylene; a phenylmethylene, a phenylethylene, a phenylpropylene or a phenylbutylene group.

[0177] The flame retardant may also be based on phosphonic acid, such as organic phosphonates with organic or inorganic cations, or phosphonates. Preferred phosphonates are diesters of alkyl or phenylphosphonic acid. Examples of phosphonates used as flame retardants according to the present invention include phosphonates of the general formula (III):

[0178]

[0179] in:

[0180] R1 represents an optionally substituted alkyl, cycloalkyl or phenyl group, wherein two R1 groups may also be bonded to each other in a ring, and

[0181] R2 is an optionally substituted alkyl, cycloalkyl or phenyl group.

[0182] The flame retardant may also be melamine or melamine cyanurate.

[0183] The flame retardant may also be a mixture of an aluminum hypophosphite-based flame retardant and a flame retardant synergist.

[0184] The flame retardant synergist is in particular as described in WO2005121234.

[0185] They may be selected from nitrogen synergists, phosphorus synergists and phosphorus / nitrogen synergists.

[0186] The nitrogen synergist preferably comprises benzoguanamine, tris(hydroxyethyl)isocyanurate, allantoin, glycoluril, melamine, melamine cyanurate, dicyandiamide, guanidine and carbodiimide.

[0187] The nitrogen synergist preferably comprises a melamine condensation product, for example, a melamine condensation product such as melem, melam or melong, or a higher degree of condensation of such compounds, or a mixture of such compounds, and can be prepared, for example, by the process described in U.S. Pat. No. 5,985,960.

[0188] The phosphorus / nitrogen synergist may comprise a reaction product of melamine with phosphoric acid or condensed phosphoric acid, or a reaction product of a melamine condensation product with phosphoric acid or condensed phosphoric acid, or may comprise a mixture of the products mentioned.

[0189] and flame retardant synergists, in particular nitrogen synergists, especially melamine-based nitrogen synergists.

[0190] About compounds selected from heat stabilizers and metal deactivators

[0191] The heat stabilizer may be an organic stabilizer, or more generally a combination of organic stabilizers, such as a primary antioxidant of the phenolic type (e.g. Irganox 245 or 1098 or 1010 types from Ciba), a secondary antioxidant of the phosphite type, and indeed even optionally other stabilizers, such as HALS meaning hindered amine light stabilizers (e.g. Tinuvin 770 from Ciba), UV absorbers (e.g. Tinuvin 312 from Ciba) or phenolic or phosphorus-based stabilizers. Amine antioxidants may also be used, such as Naugard 445 from Crompton, or multifunctional stabilizers such as Nylostab S-EED from Clariant.

[0192] The organic stabilizer may be selected from (this list is non-limiting):

[0193] - phenolic antioxidants, for example Irganox 245, Irganox 1010 or Irganox 1098 from Ciba, Irganox MD1024 from Ciba or Lowinox 44B25 from Great Lakes,

[0194] - phosphorus-based stabilizers such as phosphites, for example Irgafos 168 from Ciba,

[0195] - UV absorbers, such as Tinuvin 312 from Ciba,

[0196] -HALS, as mentioned above,

[0197] - amine stabilizers, such as Naugard 445 from Crompton, or hindered amine stabilizers, such as Tinuvin 770 from Ciba,

[0198] - Multifunctional stabilizers such as Nylostab S-EED from Clariant and the like.

[0199] The stabilizer may also be an inorganic stabilizer, such as a copper-based stabilizer.

[0200] The copper-based stabilizer can be selected from cuprous chloride, cupric chloride, cuprous bromide, cupric bromide, cuprous iodide, cupric iodide, cuprous acetate and cupric acetate. Other metal halides or acetates of the copper-based stabilizer combination can be mentioned, such as silver. These copper-based compounds are typically combined with alkali metal halides. A well-known example is a mixture of CuI and KI, wherein the ratio of CuI:KI is typically between 1:5 and 1:15. An example of such a stabilizer is Polyadd P201 from Ciba.

[0201] More details on copper-based stabilizers can be found in patent US Pat. No. 2,705,227. More recently, copper-based stabilizers have emerged, such as complex copper, for example Bruggolen H3336, Bruggolen H3337 and Bruggolen H3373 from Brüggemann.

[0202] Advantageously, the copper-based stabilizer is chosen from copper halides, copper acetates, mixtures of copper halides or acetates with at least one alkali metal halide, and mixtures thereof, preferably mixtures of copper iodide and potassium iodide (CuI / KI).

[0203] The metal deactivator used is a conventional deactivator for polyolefins; for example, hydrazide can be used.

[0204] Composition of the outer layer (II)

[0205] The composition comprises, by weight relative to the total weight of the composition:

[0206] a) at least 50% of at least one polyamide,

[0207] b) from 15% to 38% of at least one flame retardant,

[0208] c) from 4 to 20%, in particular from 4 to 15%, of polyolefins,

[0209] d) from 0 to 10% by weight, in particular from 0.1 to 10% by weight, of at least one plasticizer,

[0210] e) from 0% to 5%, in particular from 0.1% to 5%, of at least one additive,

[0211] The sum a)+b)+c)+d)+e) equals 100%.

[0212] In one embodiment, the composition comprises, by weight relative to the total weight of the composition:

[0213] a) at least 50% of at least one polyamide,

[0214] b) from 15% to 38% of at least one flame retardant,

[0215] c) from 4% to 15% of polyolefins,

[0216] d) from 0 to 10% by weight, in particular from 0.1 to 10% by weight, of at least one plasticizer,

[0217] e) from 0% to 5%, in particular from 0.1% to 5%, of at least one additive,

[0218] The sum a)+b)+c)+d)+e) equals 100%.

[0219] In a first alternative form of this embodiment, the composition comprises, by weight relative to the total weight of the composition:

[0220] a) at least 50% of at least one polyamide,

[0221] b) from 15% to 38% of at least one flame retardant,

[0222] c) from 4% to 15% of polyolefins,

[0223] d) from 0.1 to 10% by weight of at least one plasticizer,

[0224] e) from 0% to 5%, in particular from 0.1% to 5%, of at least one additive,

[0225] The sum a)+b)+c)+d)+e) equals 100%.

[0226] In a second alternative form, the composition comprises, by weight relative to the total weight of the composition:

[0227] a) at least 50% of at least one polyamide,

[0228] b) from 15% to 38% of at least one flame retardant,

[0229] c) from 4% to 15% of polyolefins,

[0230] d) from 0 to 10% by weight, in particular from 0.1 to 10% by weight, of at least one plasticizer,

[0231] e) from 0% to 5% of at least one additive,

[0232] The sum a)+b)+c)+d)+e) equals 100%.

[0233] In a third alternative form, the composition comprises, by weight relative to the total weight of the composition:

[0234] a) at least 50% of at least one polyamide,

[0235] b) from 15% to 38% of at least one flame retardant,

[0236] c) from 4% to 15% of polyolefins,

[0237] d) from 0.1 to 10% by weight of at least one plasticizer,

[0238] e) from 0.1% to 5% of at least one additive,

[0239] The sum a)+b)+c)+d)+e) equals 100%.

[0240] The invention also relates to a composition consisting by weight of the elements a) + b) + c) + d) as described in this embodiment and the three alternative forms thereof.

[0241] About Plasticizers

[0242] The plasticizer may represent up to 10% by weight, in particular it represents 0.1% to 10% by weight, relative to the total weight of the composition.

[0243] The plasticizer may be a plasticizer generally used in a polyamide-based composition.

[0244] Advantageously, plasticizers are used that exhibit good thermal stability so that no soot is formed during the blending of the various polymers and the conversion of the composition obtained.

[0245] In particular, such plasticizers may be chosen from:

[0246] benzenesulfonamide derivatives, such as n-butylbenzenesulfonamide (BBSA), n- and p-ethyltoluenesulfonamide (ETSA) isomers, N-cyclohexyltoluenesulfonamide and N-(2-hydroxypropyl)benzenesulfonamide (HP-BSA),

[0247] Parabens, such as 2-ethylhexylparaben (EHPB) and 2-hydroxydecylparaben (HDPB),

[0248] Esters or ethers of tetrahydrofurfuryl alcohol, such as oligoethyleneoxytetrahydrofurfuryl alcohol, and

[0249] Citrates or hydroxymalonates such as oligoethyleneoxymalonates.

[0250] A preferred plasticizer is n-butylbenzenesulfonamide (BBSA).

[0251] Another particularly preferred plasticizer is N-(2-hydroxypropyl)benzenesulfonamide (HP-BSA). This is because the latter exhibits the advantage of preventing the formation of precipitates on the extrusion screw and / or at the die ("die drain") during the conversion phase by extrusion.

[0252] It is quite obvious that mixtures of plasticizers can also be used.

[0253] About additives

[0254] The additive may represent up to 5% by weight, in particular from 0.1% to 5% by weight, relative to the total weight of the composition.

[0255] The at least one additive may be selected from stabilizers, dyes, adjuvants to assist the conversion (processing aids), surfactants, nucleating agents, pigments, brighteners, antioxidants, lubricants, waxes or mixtures of these.

[0256] For example, the stabilizer may be a UV stabilizer, an organic stabilizer or more generally a combination of organic stabilizers, such as a phenolic antioxidant (e.g., 245 or 1098 or 1010), phosphite type antioxidants (e.g., 126 or 168), and indeed even optionally other stabilizers, such as HALS, which means hindered amine light stabilizers (e.g. HALS from Ciba-BASF 770), UV absorbers (e.g. from Ciba 312) or phosphorus-based stabilizers. Amine antioxidants such as those from Crompton may also be used. 445, or a multifunctional stabilizer such as S-EED.

[0257] The stabilizer may also be an inorganic stabilizer, such as a copper-based stabilizer. As examples of such inorganic stabilizers, copper halides and copper acetate may be mentioned. Incidentally, other metals such as silver may optionally be considered, but these are known to be less effective. These copper-based compounds are typically combined with halides of alkali metals, in particular potassium.

[0258] In one embodiment, the additive is selected from antioxidants and color pigments.

[0259] About Structure

[0260] The structure comprises at least two layers, an inner layer (I) and an outer layer (II) as defined above.

[0261] In one embodiment, the structure consists of two layers (I) and (II) as defined above.

[0262] In another embodiment, depending on the formulation of the polyolefin or thermoplastic elastomer and polyolefin blend, a tie layer as defined above may be required to provide adhesion between layer (I) and layer (II).

[0263] The structure consists of the following layers from outside to inside:

[0264] (II) / / bonding / / (I).

[0265] Regardless of the structure, in one embodiment, the thickness of the outer layer accounts for 5% to 30% of the total thickness of the structure.

[0266] In another embodiment, the thickness of the inner layer accounts for at least 70% of the total thickness, in particular 70% to 95% of the total thickness.

[0267] In another embodiment, the thickness of the outer layer is 5% to 30% of the total thickness of the structure, and the inner layer is at least 70% of the total thickness, in particular 70% to 95% of the total thickness.

[0268] Advantageously, said at least one thermoplastic polymer P1 of the inner layer (I) is chosen from non-functionalized polyolefins, functionalized polyolefins and blends of these.

[0269] 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.

[0270] In another embodiment, the at least one thermoplastic polymer P1 of the inner layer (I) is a polyethylene non-functionalized polyolefin.

[0271] In yet another embodiment, the at least one thermoplastic polymer P1 of the inner layer (I) is a polypropylene non-functionalized polyolefin.

[0272] In a first alternative form, whether the structure comprises two or three layers, said structure comprises a layer (II) comprising a composition based on a semicrystalline aliphatic polyamide exhibiting a C4 to C 15 The average number of carbon atoms per nitrogen atom.

[0273] 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 thermal stabilizers and metal deactivators or mixtures of these.

[0274] In a second alternative form, whether the structure comprises two or three layers, said structure comprises a layer (II) comprising a composition based on a semicrystalline aliphatic polyamide exhibiting an average number of carbon atoms per nitrogen atom ranging from C4 to C9, layer (I) of said structure being made of polypropylene, in particular stabilized by a compound chosen from compounds of thermal stabilizers and metal deactivators or mixtures of these.

[0275] Advantageously, in this second alternative form, the polyamide is chosen from PA6, PA66, PA410, PA412, PA610 and PA612, in particular PA610 and PA612.

[0276] In this second alternative, the structure resides inside or outside the electric vehicle battery pack.

[0277] In this second alternative, the structure may also be present inside and / or outside the battery pack of the stationary energy storage system.

[0278] In a third alternative form, whether the structure comprises two or three layers, said structure comprises a layer (II) comprising a composition based on a semicrystalline aliphatic polyamide exhibiting C 10 To C 15 The layer (I) of the structure is made of polypropylene, in particular stabilized by a composite material chosen from heat stabilizers and metal deactivators or mixtures of these.

[0279] Advantageously, in this third alternative form, the polyamide is chosen from PA614, PA618, PA1010, PA1012, PA1014, PA1018, PA1210, PA1212, PA1214, PA1218, PA11 or PA12, in particular PA11 and PA12.

[0280] In this third alternative, the structure is present inside and / or outside of a battery pack of the electric vehicle.

[0281] In this third alternative, the structure may also be present inside and / or outside the battery pack of the stationary energy storage system.

[0282] Advantageously, in all embodiments and alternative forms of the structure, the polyolefin of the inner and outer layers is the same.

[0283] Advantageously, in all embodiments and alternative forms of the structure, the polyolefins of the inner and outer layers are different.

[0284] According to another aspect, the present invention relates to the use of a flame retardant tubular structure as defined above for cooling an electric vehicle battery or a stationary energy storage system battery.

[0285] All embodiments described above for the polyamide, polyolefin, flame retardant and structure are suitable for this use.

[0286] The invention will now be illustrated by way of non-limiting examples of the scope of the invention. Example

[0287] The compositions of Table 1 are prepared by melt blending polyamide granules with flame retardants, polyolefins and optionally plasticizers and additives. The % values ​​indicated are weight percentages relative to the total weight of the composition. The blending is carried out by compounding on a co-rotating twin-screw extruder with a diameter of 40 mm and a flat temperature profile (T°) at 250° C. The screw speed is 225 rpm and the throughput is 55 kg / h.

[0288] Polyamide, polyolefin and optionally plasticizer and additives are introduced through the main hopper during the compounding process. Flame retardant is added to the molten polymer in the middle of the screw through a side feeder. If a plasticizer is present, it is also introduced into the molten polymer through a pump.

[0289] The composition was subsequently extruded by coextrusion in the form of 8 x 1 mm tubes.

[0290] MLT (8×1 mm multilayer tubes) or monolayer tubes (8×1 mm monolayer tubes) are produced on a conventional multilayer tube extrusion line as described in EP 2 098 580 or on a conventional Maillefer 60 monolayer tube line when monolayer tubes are concerned to investigate mechanical properties and fire resistance according to the following standards.

[0291] The temperature profile for non-flame retardant as well as flame retardant PA was as follows (from the pellet feed zone to the end of the screw): 210 / 220 / 220 / 220. The temperature at the die outlet (melt) was of the order of 220°C. The polyolefin was extruded with the following temperature profile: 160 / 210 / 220 / 220. The melt temperature at the die outlet was of the order of 220°C. The outer diameter of the mandrel was 12 mm and the inner diameter of the die was 18 mm. A tube with a hole was obtained, the inner diameter of which was between 8.5 mm and 9.2 mm.

[0292] Subsequently, the above single-layer and multi-layer tubes produced by extrusion were evaluated in terms of the following aspects:

[0293] -Flexibility

[0294] -VW-40℃ shock

[0295] - Cooling type mixing aging. The tube was filled with a glycol aqueous solution (Havoline solution (50 wt%) diluted with water) and heat aged in an oven at 110°C.

[0296] The measurement results and methods are shown in Tables 2 to 4 below.

[0297] The structures of the invention and the comparative structures were tested on the outside of the tube with a flame propagation test commonly practiced, known as UL94, according to the standard (IEC 60695-11-10).

[0298] Here, the UL94 test (which is generally applied to rods of a single product) is carried out on a single-layer structure (single-layer tube) or a multi-layer structure, in particular a three-layer tube, wherein the flame contacts only the outer layer of the tube, the three-layer tube exhibiting the following layer dimensions: from outer layer to inner layer: 0.15 mm / / 0.10 mm / / 0.75 mm or 0.350 mm / / 0.10 mm / / 0.55 mm.

[0299] [Table 1]

[0300]

[0301] [Table 2]

[0302]

[0303] NC = Not Classified Worse than V-2 [Table 3]

[0304]

[0305]

[0306] [Table 4]

[0307]

[0308] (1) 8×1 mm single-layer tube and 8×1 mm multi-layer tube, the layers of the three-layer tube are distributed as follows from the outer layer to the inner layer: 0.15 mm / / 0.10 mm / / 0.75 mm and 0.35 mm / / 0.10 mm / / 0.55 mm. The double-layer tube is distributed as follows from the outer layer to the inner layer: 0.15 mm / / 0.85 mm.

[0309] (2) Flexural modulus measured at 23° C. and relative humidity: RH 50% according to ISO 178:2010, expressed in MPa.

[0310] (3) Impact according to standard VW TL-52435 §6.5, PV 3905 at -40°C, as % fracture.

[0311] (4) Ageing resistance at 110°C in air, half-life in hours, according to ISO 527-1A, (corresponding to the point where the elongation decreases by 50%.

[0312] This aging fully represents the aging of the application in air (outside the tube) / fluid (inside the tube)

[0313] A = half-life > 1500h; B = half-life > 500h and < 1500h; C = half-life < 500h.

[0314] (5) UL 94 evaluation according to IEC 60695-11-10

[0315] IM 800: Maleic anhydride modified HDPE (SK Functional Polymer)

[0316] Maleic anhydride grafted LDPE adhesive: Admer GT7 (Mitsui)

[0317] HDPE*: Lupolen GX5038 (LyondellBasell)

[0318] HDPE-g-MAH**: A blend of 93 wt% Lupolen GX5038 (LyondellBasell) and 7 wt% Orevac OE25 (SK Functional Polymer) as a dry blend. The addition of Orevac OE25, which is a LLDPE highly grafted with maleic anhydride, enables the HDPE-g-MAH to adhere to the polyamide layer.

Claims

1. A flame retardant multilayer tubular structure for cooling an electric vehicle battery or a stationary energy storage system battery, comprising at least two layers: Inner layer (I), comprising at least 40% of at least one thermoplastic polymer P1 chosen from polyolefins and thermoplastic elastomers and up to 5% by weight of a compound chosen from thermal stabilizers and metal deactivators or mixtures thereof, based on a polyolefin composition comprising by weight: An outer layer (II) comprising a composition based on at least one main polyamide, said composition comprising by weight, relative to the total weight of layer (II): a) at least 50% by weight of at least one polyamide, b) from 15 to 38% by weight of at least one flame retardant, c) from 4 to 20% by weight, in particular from 4 to 15% by weight, of polyolefins, d) from 0 to 10% by weight, in particular from 0.1 to 10% by weight, of at least one plasticizer, e) from 0 to 5% by weight, in particular from 0.1 to 5% by weight, of at least one additive, the sum a)+b)+c)+d)+e) being equal to 100%.

2. The flame retardant multilayer tubular structure according to claim 1, characterized in that The polyamide is chosen from semicrystalline aliphatic polyamides and semicrystalline semiaromatic polyamides (PPA) exhibiting an average number of carbon atoms ranging from 4 to 15 per nitrogen atom.

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

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

5. The flame retardant multilayer tubular structure according to any one of claims 3 and 4, characterized in that It is present inside the battery pack of the electric vehicle.

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

7. The flame retardant multilayer tubular structure according to claim 6, characterized in that The semi-crystalline aliphatic polyamide is selected from PA614, PA618, PA1010, PA1012, PA1014, PA1018, PA1210, PA212, PA1214, PA1218, PA11 and PA12, in particular PA11 and PA12.

8. The flame retardant multilayer tubular structure according to any one of claims 6 and 7, 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 any one of claims 3-4 and 6-7, characterized in that It exists inside and / or outside the battery pack of the stationary energy storage system.

10. The flame retardant multilayer tubular structure as claimed in 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, in particular PA11 / 10T and PA11 / 12T.

12. The flame retardant multilayer tubular structure according to claim 10 or 11, characterized in that The battery exists inside and / or outside the battery pack of the electric vehicle or the battery pack of the stationary energy storage system.

13. The flame retardant multilayer tubular structure according to any one of claims 1 to 12, characterized in that Said polyolefin P1 of the inner layer (I) is chosen from non-functionalized polyolefins, functionalized polyolefins and blends of these.

14. The flame retardant multilayer tubular structure as claimed in claim 13, characterized in that The polyolefin P1 of the inner layer (I) is a non-functionalized polyolefin, and the tubular structure comprises a tie layer (III) between the layer (I) and the layer (II).

15. The flame retardant multilayer tubular structure according to any one of claims 1 to 14, characterized in that Said polyolefin P1 of the inner layer (I) is a non-functionalized polyolefin selected from polyethylene and polypropylene.

16. The flame retardant multilayer tubular structure according to any one of claims 1 to 15, characterized in that The outer layer (II) exhibits a thickness ranging from 5% to 30% of the total thickness of the structure.

17. The flame retardant multilayer tubular structure according to any one of claims 1 to 16, characterized in that The inner layer (I) exhibits a thickness of at least 70% of the total thickness of the structure.

18. The flame retardant multilayer tubular structure according to any one of claims 14 and 15, characterized in that The outer layer (II) exhibits a thickness ranging from 5% to 30% of the total thickness of the structure, and the inner layer (I) exhibits a thickness of at least 70% of the total thickness of the structure.

19. Use of the flame retardant tubular structure according to any one of claims 1 to 18 for cooling batteries of electric vehicles or batteries of stationary energy storage systems.

Images