Polyamide element for a cooling circuit using at least one dielectric fluid

Abstract

The invention relates to the use of at least one element in a cooling circuit using at least one dielectric fluid, wherein: the dielectric fluid is liquid at atmospheric pressure at 23°C and comprises less than 10% by weight of water and glycol ether; the element consists of a polyamide composition comprising: o 35 to 85% by weight of a polyamide matrix having an average C / N ratio greater than or equal to 7; and o 15 to 65% by weight of reinforcing fibres or fillers; the element being in direct contact with the dielectric fluid.

Description

[0001] Description

[0002] Title: Polyamide element for cooling circuit using at least one dielectric fluid

[0003] Field of invention

[0004] The present invention relates to the field of cooling, in particular cooling circuits, in particular for motor vehicles of the electric or hybrid type, requiring the use of electric batteries. The present invention also relates to any other field requiring cooling circuit elements, in particular for the cooling of electric batteries.

[0005] In particular, the present invention relates to a housing for cooling battery cells, in particular those of an electric or hybrid motor vehicle, using a dielectric fluid, valves or valves for distributing the dielectric fluid in the cooling circuit, and connectors.

[0006] Technical background

[0007] One of the goals in the automotive industry is to offer increasingly less polluting vehicles. Thus, electric or hybrid vehicles with a battery aim to gradually replace thermal vehicles, such as gasoline or diesel vehicles.

[0008] However, it turns out that the battery is a relatively complex component of the vehicle. In particular, it is necessary that its operating temperature does not exceed 55°C, otherwise some of the battery cells may deteriorate, thus reducing the battery's lifespan. The battery cells must therefore be cooled.

[0009] Furthermore, it is necessary to avoid any risk of flame and to avoid contact between the battery cells and water or humidity.

[0010] To date, the solution most commonly used to cool battery cells is indirect cooling by which a metal plate, inside which a water-glycol mixture circulates, is brought into contact with the battery cells. In an alternative solution, the battery cells are included in a case, particularly made of PA66 (such as PA66 GF25), this case being cooled by a water / glycol mixture. However, this solution has several drawbacks, including water uptake in the polymer and a risk of water being released into the environment of the battery cells, which can lead to corrosion problems and loss of efficiency in power restitution. To overcome this problem, it may be necessary to use sponges in the battery storage case, which will absorb moisture. However, this solution is not optimal.Another disadvantage is the risk of water being released into the coolant, leading to fluid degradation. Furthermore, the materials currently used also exhibit poor dimensional stability and warping.

[0011] Furthermore, it is necessary to provide materials with good mechanical properties, particularly in traction and impact, preferably when cold.

[0012] Since battery electrodes cannot come into contact with a conductive liquid, water-based coolants cannot be used for direct cooling. Another major risk is that the cells may self-ignite upon contact with water, causing the fire to spread to the entire battery and then to the vehicle.

[0013] It is therefore essential to use coolants that do not contain (or contain very little) water and do not conduct electricity in order to avoid any short circuit in the battery that could cause a fire. Direct cooling can be achieved with specific fluids with very low electrical conductivity, called "dielectric fluids". "Dielectric fluids", based on hydrocarbon oils or synthetic esters, are different from the water-based coolants currently used.

[0014] There is, however, a real need to provide elements or structures adapted to the dielectric fluid and making it possible to ensure the cooling, for example, of battery cells with said dielectric fluid, in an efficient manner while avoiding any degradation of the batteries, the element or the structure and said dielectric cooling fluid.

[0015] There is also a need to provide materials compatible with dielectric fluids, exhibiting low water uptake, good dimensional stability and low permeability for manufacturing the cases (or modules) containing the battery cells for cooling said battery cells.

[0016] There is therefore a need to provide elements (or structures) suitable for said dielectric fluids. It is necessary to provide elements which have the following property(ies):

[0017] - mechanical resistance and in particular not seeing its stress or elongation at break modified by more than 50%, in particular by soaking in the dielectric fluid between -60 and 140°C whether in the short term (<168 hours) or in the long term (>10,000 h); - the possibility of being recycled, preferably by a mechanical recycling process;

[0018] - resistance to fluid pressure, generally between 1 and 6 bars;

[0019] - resistance to chemical attacks from the fluid internally and from various components externally, in particular de-icing salts;

[0020] - thermal resistance;

[0021] - resistance to hydrolysis;

[0022] - a low accumulation of electric charge linked to the friction of the dielectric fluid on the internal surface of said element, in particular in the case of a box or module;

[0023] - low electrical resistivity, volume or surface, typically less than 10 6 Ohms. Surface electrical resistivity measurements can be made according to ASTM D257-14 of 2021;

[0024] - resistance to the release of soluble or insoluble products which could modify the properties of the dielectric fluid or damage one or other of the components of the direct cooling circuit,

[0025] - resistance to the release of products that harm the dielectric nature of the fluid, particularly of the ionic species type (anionic or cationic).

[0026] - good dimensional stability and low warping

[0027] There is more particularly a need to provide elements (or structures) adapted to said dielectric fluids which have mechanical resistance and in particular do not see their stress or elongation at break modified by more than 50%, in particular by soaking in the dielectric fluid between -60 and 140°C whether in the short term (<168 hours) or in the long term (>10,000 h).

[0028] There is a real need to provide such elements which exhibit at least one of these properties throughout the entire lifespan of the vehicle, in particular between 3000 and 10000 hours, including both the driving phases and the static load phases of the vehicles on which they are mounted.

[0029] Summary of the invention

[0030] The present application relates to the use of at least one element in a cooling circuit using at least one dielectric fluid, in which: said dielectric fluid is liquid at atmospheric pressure at 23°C and comprises less than 10% by weight of water and glycol ether; the element is made of a polyamide C composition comprising: o from 35 to 85% by weight of a polyamide matrix having an average C / N ratio greater than or equal to 7; o from 15 to 65% by weight of reinforcing fibers or fillers, said element being in direct contact with the dielectric fluid.

[0031] Preferably, the polyamide matrix has an average C / N ratio greater than or equal to 8, preferably greater than or equal to 9, preferably between 9 and 12.

[0032] Preferably, composition C has an inherent viscosity of between 1 and 1.8, preferably between 1.1 and 1.6, more preferably between 1.15 and 1.4.

[0033] Preferably, the dielectric fluid comprises one or more compounds chosen from mineral oils and mineral oil derivatives, polyalphaolefins, polyalkylene glycols, silicones, esters with a number-average molar mass of between 1000 and 100,000 g / mol, for example polyol ester, POE, partially fluorinated polymers having a number-average molar mass of 1000 and 100,000 g / mol, for example perfluoropolyethers.

[0034] Preferably, the dielectric fluid has a density measured according to ISO 1675:2022 at 23°C of between 0.3 and 1.5, preferably between 0.5 and 1.1, advantageously between 0.7 and 1.05, more preferably between 0.8 and 1.

[0035] Preferably, the dielectric fluid has a kinematic viscosity at 40°C of between 1 and 35 mm 2 / s, preferably between 1.5 and 15 mm 2 / s, especially between 2 and 10 mm 2 / s and / or a kinematic viscosity at 100°C between 0.01 and 5 mm 2 / s, preferably between 0.1 and 4 mm 2 / s, preferably between 0.5 and 3 mm 2 / s, more preferably between 0.8 and 2.5 mm 2 / s and / or a kinematic viscosity at 25°C between 5 and 150 mm 2 / s, preferably between 10 and 100 mm 2 / s, the kinematic viscosity being measured according to ISO 3104:2020.

[0036] Preferably, composition C further comprises from 0.01 to 1.5%, preferably from 0.05 to 0.5%, more preferably from 0.1 to 0.4%, by weight of a thermal stabilizer relative to the total weight of composition C.

[0037] Preferably, the composition further comprises: From 10 to 35%, preferably from 15 to 25%, by weight of a flame retardant, preferably a non-halogenated flame retardant, preferably a phosphorus-containing flame retardant; and / or

[0038] From 1 to 35% by weight, preferably from 2 to 10% by weight of at least one impact modifier; and / or

[0039] From 0.5 to 30% by weight of at least one current-conducting filler; and / or

[0040] From 0.1 to 10% by weight of at least one additive.

[0041] Preferably, composition C comprises a plasticizer content of less than 10%, preferably less than 6%, preferably less than 5%, preferably less than 3%, preferably less than 1%, by weight, preferably composition C is free of plasticizer, such as BBSA (N-Butyl Benzene Sulfonamide).

[0042] Preferably, the element comprises at least one inlet and at least one outlet allowing the circulation of the dielectric fluid.

[0043] Preferably, the element is a housing or module for direct cooling of battery cells, said battery cells being in contact with the dielectric fluid in said housing or module.

[0044] Preferably, the element is an element for distributing the dielectric fluid, for example a valve or a valve, and having an inlet and at least two outlets or comprising at least two inlets and one outlet, the element can also be a connector.

[0045] The present invention also relates to a device for the direct cooling of battery cells using a dielectric fluid comprising: at least one housing (BX) adapted to receive battery cells and provided with an inlet and an outlet allowing the circulation of a dielectric fluid in said housing in direct contact with the battery cells;

[0046] A dielectric fluid included in said housing (BX);

[0047] Said box (BX) being made up of a composition described above;

[0048] The dielectric fluid being as defined above.

[0049] The invention also relates to a device for the direct cooling of battery cells by a dielectric fluid comprising:

[0050] - A dielectric fluid;

[0051] - Optionally at least one element a tank (R1);

[0052] - At least one housing (BX) adapted to receive battery cells and provided with an inlet and an outlet allowing the circulation of a dielectric fluid in said housing in direct contact with the battery cells; - Upstream of the housing(s) (BX) at least one element (E1) for the distribution of the dielectric fluid to the housing(s) (BX), the element (E1) comprising an inlet for the dielectric fluid and x outlets connected to the housings (BX), x corresponding to the number of housings (BX), each of the outlets being connected to a housing (BX);

[0053] - Downstream of the housings (BX) at least one element (E2), preferably according to the invention, for recovering the dielectric fluid coming from the housings (BX), the element (E2) comprising y inlets for the dielectric fluid and z outlets, y corresponding to the number of housings (BX) connected to the element (E2) and z corresponding to the number of cooling systems (S1), each of the inlets being connected to a housing (BX) and each of the outlets being connected to at least one cooling system (S1);

[0054] - at least one cooling system (S1), preferably a radiator, allowing the cooling of the dielectric fluid coming from the element (E2);

[0055] - elements, in particular in the form of a pipe in which said dielectric fluid circulates between the reservoir (R1), the element (E1), the boxes (BX), the element (E2) and the cooling system (S1);

[0056] - The housing(s) (BX) and / or, preferably and, the elements (E1) and (E2) being made of a composition as described above;

[0057] - The dielectric fluid being as defined above.

[0058] Preferably, the inlets of the boxes (BX) are equipped with a nozzle allowing the spraying of the dielectric fluid directly onto the battery cells, preferably the nozzle is made of a polyamide composition comprising from 35 to 85% by weight of a polyamide matrix preferably having an average C / N ratio greater than or equal to 7 and from 15 to 65% by weight of reinforcing fibers or fillers.

[0059] Preferably, the pipes are connected to the inlets and / or outlets of the boxes (BX), of the elements (E1) and (E2) directly or using connectors, preferably made of a polyamide composition comprising from 35 to 85% by weight of a polyamide matrix preferably having an average C / N ratio greater than or equal to 7 and from 15 to 65% by weight of reinforcing fibers or fillers.

[0060] The device described above may be included in a container comprising an inlet and an outlet each equipped with a pipe, or a plurality of pipes connected together by connectors, and allowing the circulation of said dielectric fluid. The polyamide composition according to the invention is particularly suitable for the dielectric fluid used in particular for cooling battery cells. Thus, the dielectric fluid will not see its composition modified in contact with the elements according to the invention comprising the polyamide composition of the invention. Particularly advantageously, after aging for 500 hours at 130°C, the dielectric fluid in contact with the polyamide composition according to the invention does not comprise more than 0.5% by mass, preferably 0.2%, advantageously 0.1% by mass of impurities not initially present.This test is performed by immersing a “1 BA” test piece (according to ISO 527) in 100 mL of dielectric fluid according to the invention. The dielectric fluid is preferably Mobil EV therm Elite 701®. These impurities are quantified in two ways:

[0061] - the dielectric fluid is filtered then the residue is weighed after washing and drying (when the mass no longer varies during drying).

[0062] - Soluble impurities are quantified by liquid chromatography, in particular HPLC, by comparing the chromatograms before and after aging of the composition in the fluid.

[0063] The impurities according to the invention may be additives, monomers or oligomers, plasticizers or fillers initially included in the polyamide of the composition or impurities having migrated through the composition such as for example other automotive fluids such as lubricants or greases. The impurities are for example phosphorus species and / or BBSA (N-Butyl Benzene Sulfonamide). The pollution of the fluids by phosphorus species and by BBSA can be measured indirectly by monitoring the evolution of the contents of elements P and S. These contents can be determined by inductively coupled plasma torch spectroscopy according to standard ASTM D5185.The migration of antioxidants can be assessed qualitatively and quantitatively by fluid analysis in high-performance liquid chromatography coupled with appropriate detection systems for their detection, such as UV photometry or high-resolution mass spectrometry. The identity of the targeted antioxidants must be confirmed (i) by concordance of retention times between the substances recorded in the sample chromatograms and those recorded in the analysis of standards, (ii) by concordance of mass spectra.

[0064] Preferably, after the aging described above (500 hours at 130°C), the conductivity of the dielectric fluid is less than 1 pS / cm, preferably less than 0.1 pS / cm, more preferably less than 0.01 pS / cm. The resistivity of the fluid is measured according to DIN IEC 60247, which allows the conductivity to be calculated.

[0065] The water content in the dielectric fluid after aging is determined according to the Karl Fisher method following the ISO 760:1978 standard. This aging is carried out by placing the dielectric fluid in contact with a hermetically sealed element according to the invention for 1000 h. The element according to the invention is placed in a controlled atmosphere at 50% relative humidity and at a temperature of 50°C. The thickness of the walls of the element is 2 mm. The water content in the dielectric fluid after this aging is less than 2% by weight, preferably 1% by weight, in particular 0.5% by weight, advantageously 0.1% by weight, in particular 0.05% by weight (the water content of the fluid before aging is less than 50 ppm).

[0066] Presentation of figures

[0067] Figure 1 shows a housing made of a polyamide composition (1) according to the invention comprising an inlet (4) and an outlet (5). The housing comprises battery cells (2). A flow of dielectric fluid (3) going from the inlet (4) to the outlet (5) cools the battery cells (2) by direct contact.

[0068] Figure 2 represents a cooling circuit for battery cells comprising two housings (B1) and (B2) made of a polyamide composition according to the invention comprising battery cells. Each of the housings (B1) and (B2) comprises an inlet and an outlet allowing the flow of dielectric fluid (3). The cooling circuit also comprises two elements (E1) and (E2) made of a polyamide composition according to the invention and allowing the distribution of the dielectric fluid in the housings (B1) and (B2).

[0069] Figure 3 represents a cooling circuit for battery cells comprising two housings (B1) and (B2) made of a polyamide composition according to the invention comprising battery cells. Each of the housings (B1) and (B2) comprises an inlet and an outlet allowing the flow of dielectric fluid (3). The cooling circuit also comprises two elements (E1) and (E2) made of a polyamide composition according to the invention and allowing the distribution of the dielectric fluid in the housings (B1) and (B2) via the pipes (T).

[0070] Detailed description

[0071] The invention is now described in more detail and in a non-limiting manner in the following description.

[0072] Unless otherwise stated, all percentages are by mass. In this text, the quantities indicated for a given species may apply to that species according to all its definitions (as mentioned in this text), including the more restricted definitions.

[0073] It is further specified that the expressions "between... and..." and "from... to..." used in this description must be understood as including each of the limits mentioned.

[0074] The term "polyamide matrix" is intended to denote a composition of one or more polyamides. In the context of the present invention, the polyamide matrix represents more than 25% by weight, preferably more than 35% by weight of the polyamide composition. In the context of the present invention, all the components included in the polyamide composition according to the invention are dissolved or dispersed in the polyamide matrix.

[0075] The term "direct cooling" refers to the cooling of battery cells by direct contact of said battery cells with the dielectric heat transfer fluid. In so-called "indirect" cooling, the battery cells are not in direct contact with the heat transfer fluid. In indirect cooling processes, there is an element that physically isolates the battery cells from the heat transfer fluid. This element acts as a heat exchanger between the heat transfer fluid and the battery cells. These elements may notably be in the form of cooling plates, cooling channels, or any other equivalent device allowing such circulation of heat transfer fluid within it.

[0076] The invention relates firstly to the use of at least one element in a cooling circuit using at least one dielectric fluid, in which: Said dielectric fluid is liquid at atmospheric pressure at 23°C and comprises less than 10% by weight of water and glycol ether; the element is made of a polyamide C composition comprising: o from 35 to 85% by weight of a polyamide matrix having an average C / N ratio greater than or equal to 7; o from 15 to 65% by weight of fillers or reinforcing fibers.

[0077] Preferably, the cooling circuit is a direct cooling circuit.

[0078] Preferably, the element is intended to be in direct contact with the dielectric fluid. Preferably, the element is in direct contact with the dielectric fluid. Polyamide matrix

[0079] The composition according to the invention preferably comprises from 35 to 85%, preferably from 50 to 80%, by weight of polyamide matrix relative to the total weight of the composition.

[0080] The polyamide(s) of the polyamide matrix are chosen so that the average C / N ratio of the polyamide mixture of the polyamide matrix is ​​greater than or equal to 7, preferably greater than or equal to 8, preferably greater than or equal to 9, preferably between 9 and 12.

[0081] The composition of the invention comprises less than 20% by weight, preferably less than 10% by weight, for example less than 5% by weight, preferably less than 3% by weight, in particular 0% by weight, relative to the total weight of the composition of one or more polyamides having a C / N ratio of less than 7.

[0082] By average number of carbon atoms per nitrogen atom, we mean the average number of carbon atoms per unit, that is to say per chain between two nitrogen atoms. Within a polyamide, the units are linked to each other by amide functions: -CO-NH-. Thus, there are as many nitrogen atoms as there are amide groups (-CO-NH-). In the case of a homopolyamide of the PA-XY type, the number of carbon atoms per nitrogen atom is the average of the unit X and the unit Y. Thus, PA612 resulting from the polycondensation of hexanediamine and dodecanedioic acid, is a PA with 9 carbon atoms per nitrogen atom, in other words is a C9 PA, according to the following calculation: (6+12) / 2. 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 in molar proportion to the different amide units. Thus, coPA- 6.T / 6.6 comprising 60% 6T and 40% 66 is in C6.6 60%x[(6+8) / 2]+40%x[(6+6) / 2] = 6.6.In the case of a polyamide blend, the number of carbon atoms per nitrogen atom is calculated according to the same principle. The calculation is carried out in molar proportion to the different polyamides. Thus, for a blend of polyamide A and polyamide B comprising 60% A and 40% B, the average C / N ratio is [60% x (C / N ratio of A) + 40% x (C / N ratio of B)] / 2.

[0083] Preferably, the composition C according to the invention has an inherent viscosity of between 1 and 1.8, preferably between 1.1 and 1.6, more preferably between 1.15 and 1.4. Preferably, the polyamide matrix according to the invention has an inherent viscosity of between 1 and 1.8, preferably between 1.1 and 1.6, more preferably between 1.15 and 1.4. For the purposes of the application, the inherent viscosity of the polyamide matrix is ​​measured after dissolution of the polymer matrix.

[0084] The inherent viscosity is determined in m-cresol according to ISO 307:2007 but by changing the solvent (using m-cresol instead of sulfuric acid and the temperature being 20°C).

[0085] The term polyamide refers to both homopolyamide and copolyamide.

[0086] The nomenclature used to define polyamides is described in ISO 1874-1:2011 "Plastics - Polyamide (PA) materials for molding and extrusion - Part 1: Designation", particularly on page 3 (tables 1 and 2) and is well known to those skilled in the art.

[0087] The polyamide can be obtained from the polycondensation of lactam units, amino acid units and / or XY units, X denoting a diamine and Y denoting a dicarboxylic acid (or diacid).

[0088] Lactams and amino acids contain from 4 to 12 carbon atoms. Preferably, they are chosen from pyrrolidinone, 2-piperidinone, caprolactam, aminohexanoic acid, pelargolactam, decanolactam, undecanolactam, 10-aminoundecanoic acid, amino-11-undecanoic acid, amino-12-dodecanoic acid, lauryllactam, enantholactam, caprylolactam.

[0089] Advantageously, the lactams and amino acids are C11 and C12.

[0090] The diamine can be aliphatic, linear or branched, or cycloaliphatic, preferably it is linear or branched aliphatic, especially linear. The dicarboxylic acid can be aliphatic, cycloaliphatic or aromatic, preferably it is aliphatic or aromatic.

[0091] Concerning the polyamides obtained from the polycondensation of XY units, the diamine (X) can be C4 to C36, in particular C6 to C22, in particular C6 to C18 and the dicarboxylic acid (Y) can be C4 to C36, in particular C6 to C22, in particular C6 to C18.

[0092] Advantageously, the diamine is chosen from butanediamine, pentanediamine, 2-methyl-1,5-pentanediamine, 1,6-hexamethylenediamine, 1,7-heptanediamine, 1,8-octanediamine, 1,9-nonanediamine, 2-methyl-1,8-octanediamine, 2,2,4-trimethylhexamethylenediamine, 2,4,4-trimethylhexamethylenediamine, 1,10-decanediamine, 1,11-undecanediamine, 2-butyl-2-ethyl-1,5-pentanediamine, 1,12-dodecanediamine, 1,13-tridecanediamine, 1,14-tetradecanediamine, hexadecanediamine, octadecanediamine, octadecenediamine, eicosanediamine, docosanediamine and diamines obtained from fatty acids, 1,3-xylylenediamine (denoted MXD) and 1,4-xylylenediamine (denoted PXD), 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'-dimethyl-4,4'-diamino-dicyclohexyl-methane commonly called "BMACM" or "MACM" (and noted B hereinafter), p-bis(aminocyclohexyl)-methane commonly called "PACM" (and noted P hereinafter), isopropylidenedi(cyclohexylamine) commonly called "PACP", isophorone-diamine (noted IPD hereinafter) and 2,6-bis(amino methyl)norbornane commonly called "BAMN", in particular 1,10-decanediamine.,

[0093] A non-exhaustive list of cycloaliphatic diamines is given in the publication "Cycloaliphatic Amines" (Encyclopaedia of Chemical Technology, Kirk-Othmer, 4th Edition (1992), pp. 386-405).

[0094] Advantageously, the dicarboxylic acid is chosen from succinic acid, pentanedioic acid, adipic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, brassylic acid, tetradecanedioic acid, hexadecanedioic acid, octadecanoic acid, octadecenoic acid, eicosanedioic acid, docosanedioic acid and fatty acid dimers containing 36 carbons, terephthalic acid (denoted T), isophthalic acid (denoted I), in particular dodecanedioic acid.

[0095] Advantageously, the diamine is chosen from 1,8-octanediamine, 1,9-nonanediamine, 2-methyl-1,8-octanediamine, 2,2,4-trimethylhexamethylenediamine, 2,4,4-trimethylhexamethylenediamine, 1,10-decanediamine, 1,3-bis(aminomethyl)cyclohexane (BAC), 1,11-undecanediamine, 2-butyl-2-ethyl-1,5-pentanediamine, 1,12-dodecanediamine, 1,13-tridecanediamine, 1,14-tetradecanediamine, in particular 1,10-decanediamine, and the dicarboxylic acid is chosen from sebacic acid, undecanedioic acid, dodecanedioic acid, brassylic acid, tetradecanedioic acid, terephthalic acid (denoted T), isophthalic acid (denoted I), in particular dodecanedioic acid.

[0096] More advantageously, the lactam is lauryllactam, the amino acid is chosen from 10-aminoundecanoic acid, amino-11-undecanoic acid, amino-12-dodecanoic acid, the diamine is chosen from 2-methyl-1,5-pentanediamine, 1,5-pentanediamine, 1,6-hexamethylenediamine, 1,9-nonanediamine, 2-methyl-1,8-octanediamine, 1,10-decanediamine, and 1,12-dodecanediamine and the dicarboxylic acid is chosen from adipic acid, sebacic acid, dodecanedioic acid, terephthalic acid (denoted T) and isophthalic acid (denoted I).

[0097] According to a very preferred embodiment, the lactam is lauryllactam, the amino acid is chosen from 10-aminoundecanoic acid, amino-11-undecanoic acid, amino-12-dodecanoic acid, the diamine is chosen from Ha butanediamine, 1,5-pentanediamine, 1,6-hexamethylenediamine, 1,10-decanediamine and 1,12-dodecanediamine and the dicarboxylic acid is chosen from adipic acid, sebacic acid, dodecanedioic acid, terephthalic acid (denoted T) and brassylic acid, tetradecanedioic acid.

[0098] Advantageously, the polyamide present in the composition of the invention is chosen from PA 410, PA412, PA 510, PA 610, PA612, PA 613 PA1010, PA10T, PA10T / 1010, PA11, PA12, PA11 / 10T, PA12 / 10T, PA 1012, PA 1212, PA 1214 PA 618, PA 12T, PA 1010 / 1012, PA BACT / 6T, PA BACT / 10T, PA BACT / 12T, PA MPMDT / 6T, PA MPMDT / 10T, PA MPMDT / 12T, PA MXDT / 6T, PA MXDT / 10T, PA MXDT / 12T, PA11 / BACT / 6T, PA 11 / BACT / 10T, PA 11 / BACT / 12T, PA 11 / MPMDT / 6T, PA 11 / MPMDT / 10T, PA 11 / MPMDT / 12T, PA 11 / MXDT / 6T, PA 11 / MXDT / 10T, PA 11 / MXDT / 12T, PA610 / 6T, PA612 / 6T, and a mixture thereof. Preferably, the polyamide constituting the matrix of the invention is chosen from PA12, PA 11, PA 410, PA412, PA 510, PA 610, PA612, PA 613 PA1010, PA 1012, PA9T, PA10T, PA6T / 10T, PA6T / 1010, PA10T / 1010, PA610 / 6T, PA612 / 6T and PA11 / 10T, and a mixture thereof. Preferably, the polyamide constituting the matrix of the invention is chosen from PA12, PA 11, PA 410, PA412, PA 510, PA 610, PA612, PA 613 PA1010, PA 1012, PA610 / 6T, PA612 / 6T.

[0099] Reinforcing fibers and fillers

[0100] The polyamide composition C according to the invention comprises from 15 to 65%, preferably from 20 to 55%, even more preferably from 30 to 50% by weight of reinforcing fibers or fillers, preferably reinforcing fibers, relative to the total weight of said composition C.

[0101] Preferably, the polyamide C composition according to the invention comprises from 15 to 65%, preferably from 20 to 55%, even more preferably from 30 to 50% by weight of reinforcing fibers.

[0102] The fibers present in composition C of the invention may be of different dimensions. The reinforcing fibers may be described as short, long or continuous fibers. A mixture of these fibers of different dimensions and / or of different nature may also be used.

[0103] Preferably, the so-called short fibers have a length of between 200 and 400 μm. The so-called long fibers preferably have a length greater than 1000 μm. The length of the glass fibers is measured according to the ISO 22314: 2006(E) standard. The long fibers are chosen from continuous fibers or from long fibers cut after coating with the other constituents of the composition according to the invention (long fiber compounds or long fiber thermoplastics (LFT) in English).

[0104] The fibers present in composition C of the invention preferably have an average length of between 250 and 15,000 pm, advantageously an average length of between 300 and 10,000 pm, in particular an average length of between 350 and 5,000 pm, in particular an average length of between 400 and 2,000 pm.

[0105] These reinforcing fibers may be chosen from: mineral fibers, these having high melting temperatures Tf and higher than the melting temperature Tf of said polyamide present in the matrix of the composition of the invention and higher than the polymerization and / or processing temperature, polymeric or polymer fibers having a melting temperature Tf' or, failing Tf', a glass transition temperature Tg', higher than the polymerization temperature or higher than the melting temperature Tf of said polyamide present in the matrix of the composition of the invention and higher than the processing temperature, natural fibers, or mixtures of the fibers mentioned above.

[0106] Mineral fibers suitable for the invention include carbon fibers, which include nanotube fibers or carbon nanotubes (CNTs), carbon nanofibers or graphenes; silica fibers such as glass fibers, in particular of type E, R or S2; boron fibers; ceramic fibers, in particular silicon carbide fibers, boron carbide fibers, boron carbonitride fibers, silicon nitride fibers, boron nitride fibers, basalt fibers; fibers or filaments based on metals and / or their alloys; fibers of metal oxides, in particular alumina (AI2O3); metallized fibers such as metallized glass fibers and metallized carbon fibers or mixtures of the aforementioned fibers.

[0107] As polymeric fibers suitable for the invention, mention may be made of: fibers based on amorphous thermoplastic polymer and having a glass transition temperature Tg greater than the Tg of the polyamide or mixture of polyamides present in the matrix, when the latter is amorphous; or greater than the Tf of the polyamide or mixture of polyamides present in the matrix, when the latter is semi-crystalline. Advantageously, they are based on semi-crystalline thermoplastic polymer and have a melting temperature Tf greater than the Tg of the polyamide or mixture of polyamides present in the matrix, when the latter is amorphous; or greater than the Tf of the polyamide or mixture of polyamides present in the matrix when the latter is semi-crystalline. Thus,there is no risk of fusion for the organic fibers constituting the reinforcement material during impregnation by the thermoplastic matrix of the final composite. thermosetting polymer fibers and more particularly chosen from: unsaturated polyesters, epoxy resins, vinyl esters, phenolic resins, polyurethanes, cyanoacrylates and polyimides, such as bis-maleimide resins, aminoplasts resulting from the reaction of an amine such as melamine with an aldehyde such as glyoxal or formaldehyde, thermoplastic polymer fibers and more particularly chosen from: polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyamide fibers, aramid fibers (such as Kevlar®) and aromatic polyamides such as those corresponding to one of the formulas: PPDT, MPDI, PAA and PPA, with PPD and MPD being respectively p- and m-phenylenediamine,PAA being polyarylamides and PPA being polyphthalamides, polyamide block copolymer fibers such as polyamide / polyether, polyarylether ketone (PAEK) fibers such as polyetherether ketone (PEEK), polyetherketone ketone (PEKK), polyetherketoneetherketone ketone (PEKEKK).,

[0108] Among the fibers of natural origin, and in particular plant-based, we can cite fibers based on flax, castor oil, wood, kenaf, coconut, hemp, jute, lignin, bamboo, silk, in particular spider silk, sisal, and other cellulosic fibers, in particular viscose. These fibers of plant origin can be used pure, treated or coated with a coating layer, in order to facilitate the adhesion and impregnation of the polymer matrix.

[0109] Reinforcing fibers can be a fibrous material, which can also be a fabric, braided or woven with fibers. It can also correspond to fibers with holding threads. These constitutive fibers can be used alone or in mixtures. Thus, organic fibers can be mixed with mineral fibers to be impregnated with the polymer matrix and form the pre-impregnated fibrous material.

[0110] Organic fiber strands can have several weights. They can also have several geometries. The fibers can be in the form of short fibers, which then make up felts or nonwovens which can be in the form of strips, sheets, or pieces, or in the form of continuous fibers, which make up 2D fabrics, braids or strands of unidirectional (UD) fibers or nonwovens. The fibers constituting the fibrous material can also be in the form of a mixture of these reinforcing fibers of different geometries.

[0111] Preferably, the fibrous material consists of continuous carbon, glass or silicon carbide fibers or their mixture, in particular carbon fibers. It is used in the form of a strand or several strands.

[0112] Preferred short reinforcing fibers are short fibers selected from: carbon fibers, including metallized, glass fibers, including metallized type E, R, S2, aramid fibers (such as Kevlar®) or aromatic polyamides, polyarylether ketone (PAEK) fibers, such as polyetherether ketone (PEEK), polyetherketone ketone (PEKK) fibers, polyetherketoneetherketone ketone (PEKEKK) fibers or mixtures thereof.

[0113] Particularly preferably, the fibers of the invention are glass or carbon fibers. Preferably, the fibers of the invention are short glass or carbon fibers.

[0114] Carbon fibers include carbon nanotube (CNT) fibers, carbon nanofibers, or graphenes.

[0115] Glass fibers can be type E, R or S2.

[0116] Polyamide C composition

[0117] The polyamide C composition according to the invention may further comprise at least one thermal stabilizer.

[0118] If present, the heat stabilizer is used in contents of 0.01 to 1.5%, preferably 0.05 to 0.5%, more preferably 0.1 to 0.4% by weight relative to the total weight of the polyamide composition.

[0119] The heat stabilizer may be selected from a metal-based stabilizer, an organic stabilizer, and a mixture thereof. The metal-based stabilizer may consist of one or more constituents selected from iron-based or copper-based compounds such as cuprous chloride, cupric chloride, cuprous bromide, cupric bromide, cuprous iodide, cupric iodide, cuprous acetate, and cupric acetate. Halides and acetates of other metals such as silver may be mentioned. These copper-based compounds are typically combined with alkali metal halides. A well-known example is the mixture of Cul and Kl, where the Cul:KI ratio is typically between 1:5 and 1:15. An example of such a stabilizer is Polyadd P201® from Ciba. Further details on copper-based stabilizers can be found in US Patent 2,705,227.More recently, complexed metal-based stabilizers have appeared, such as complexed coppers such as Bruggolen H3336®, H3337®, H3373® from the Brueggemann company. The metal-based stabilizers are preferably in non-ionic form, advantageously complexed, this advantageously makes it possible to avoid the release of ions into the dielectric fluid which would lead to an increase in the ionic (electrical) conductivity of said dielectric fluid.

[0120] The organic stabilizer can be chosen, without this list being restrictive, from:

[0121] - phenolic antioxidants, for example Irganox 245®, Irganox 1010®, Irganox 1098® from BASF, Irganox MD1024® from BASF, Lowinox 44B25® from SI Group,

[0122] - phosphorus-based stabilizers, such as phosphites, for example Irgafos 168® from Ciba,

[0123] - a UV absorber, such as Tinuvin 312® from BASF,

[0124] - a HALS, as previously mentioned,

[0125] - an amine-type stabilizer, such as Naugard 445® from Crompton, or a hindered amine-type stabilizer such as Tinuvin 770® from BASF,

[0126] - a multifunctional stabilizer such as Nylostab S-EED® from Clariant.

[0127] We can of course consider a mixture of two or more of these organic stabilizers.

[0128] Preferably, the heat stabilizer is non-halogenated and preferably chosen from amine type stabilizers.

[0129] In one embodiment, the stabilizer is a mixture of phenolic antioxidants and phosphites.

[0130] The polyamide composition according to the invention may further comprise:

[0131] From 10 to 35%, preferably from 15 to 25%, by weight of a flame retardant (or flame retardant, or flame retardant), preferably a non-halogenated flame retardant, preferably a phosphorus-containing flame retardant; and / or

[0132] - From 1 to 35% by weight, preferably from 2 to 10% by weight of at least one impact modifier; and / or

[0133] - From 0.5 to 30%, preferably from 2 to 25%, by weight of at least one current-conducting filler; and / or

[0134] - From 0.1 to 10%, preferably from 0.2 to 5%, by weight of at least one additive.

[0135] Preferably, the flame retardant is chosen from halogen-free flame retardants, as described in US 2008 / 0274355 and in particular a metal salt chosen from a metal salt of phosphinic acid, a metal salt of diphosphinic acid, a polymer containing at least one metal salt of phosphinic acid, a polymer containing at least one metal salt of diphosphinic acid. The flame retardant may also be chosen from red phosphorus, an antimony oxide, a zinc oxide, an iron oxide, a magnesium oxide, metal borates, such as a zinc borate, melamine pyrophosphates, melamine cyanurates, anti-drip agents of a silicone or fluorinated nature. The flame retardant may also be a mixture of the aforementioned agents.

[0136] They can also be halogenated flame retardants such as brominated or polybrominated polystyrene, brominated polycarbonate or brominated phenol.

[0137] The flame retardant agent may also be chosen from the metal salt of phosphinic acid of the following formula (I) and the metal salt of diphosphinic acid of the following formula (II): with

[0138] R1 and R2, independently of each other, denote a linear or branched C1-C6 alkyl group, or an aryl group; R3 represents a linear or branched C1-C10 alkylene, C6-C10 arylene, C6-C10 alkylarylene, or C6-C10 arylalkylene group,

[0139] M is an ion of Mg, Ca, Al, Sb, Sn, Ge, Ti, Zn, Fe, Zr, Ce, Bi, Sr, Mn, Li, Na, K and / or a protonated amine base m denotes an integer from 1 to 4, n denotes an integer from 1 to 4, x denotes an integer from 1 to 4, n and m being chosen so that the salt is neutral, i.e. it does not carry an electric charge.

[0140] Preferably, M represents a calcium, magnesium, aluminum or zinc ion.

[0141] Preferably, R1 and R2, independently of each other, denote a methyl, ethyl, n-propyl, iso-propyl, n-butyl, tert-butyl, n-pentyl and / or phenyl group.

[0142] Preferably, R3 represents a methylene, ethylene, n-propylene, iso-propylene, n-butylene, tert-butylene, n-pentylene, n-octylene, n-dodecylene group; phenylene, naphthylene; methylphenylene, ethylphenylene, tert-butylphenylene, methylnaphthylene, ethylnaphthylene, tert-butylnaphthylene; phenylmethylene, phenylethylene, phenylpropylene, or phenylbutylene.

[0143] The flame retardant may be the product with the trade name Exolit OP 1230® sold by Clariant, which is the aluminum salt of diethylphosphinic acid salt (CAS No. 225789-38-8).

[0144] More particularly, the content of flame retardant agent is between 10 and 35% by weight, preferably 15 and 25% by weight, and more particularly between 17 and 23% by weight relative to the total weight of the composition.

[0145] In a preferred embodiment, a synergist is also present. The flame retardant synergist agents are in particular as described in WO2005121234. They may be chosen from nitrogen synergists and phosphorus / nitrogen synergists. The synergist may be added in a content of between 3 and 20% by weight relative to the total weight of the composition.

[0146] The polyamide composition according to the invention may comprise at least one impact modifier. Preferably, it may comprise from 1 to 35%, preferably from 1.5 to 20%, more preferably from 2 to 10%, by weight relative to the total weight of the composition of at least one impact modifier.

[0147] The impact modifier is advantageously made of a polymer having a flexural modulus of less than 100 MPa measured according to ISO 178 at 50% RH and a Tg of less than 0°C measured according to ISO 11357-2 of 2013. The glass transition temperature Tg of the polyamides is measured using a differential scanning calorimeter (DSC), after a second heating pass, according to ISO 11357-2:2013. The heating and cooling rate is 20°C / min.

[0148] Preferably, the impact modifier consists of one or more polyolefins, some or all of which carry a function chosen from carboxylic acid, carboxylic anhydride and epoxide functions. In particular, the polyolefin may be chosen from an ethylene and propylene copolymer with an elastomeric character (EPR), an ethylene-propylene-diene copolymer with an elastomeric character (EPDM) and an ethylene / alkyl (meth)acrylate copolymer.

[0149] The composition may comprise up to 20% by weight, relative to the total weight of said composition, of a semi-crystalline polyolefin or a mixture of polyolefins, having a flexural modulus, measured according to standard ISO 178 at 50% RH, greater than 300 MPa, advantageously greater than 800 MPa.

[0150] This impact modifier can be a functionalized polyolefin (B1).

[0151] According to the invention, functionalized polyolefin (B1) means the following polymers.

[0152] The functionalized polyolefin (B1) can be an alpha-olefin polymer having reactive units: functionalities. Such reactive units are carboxylic acid, anhydride, or epoxy functions.

[0153] By way of example, polyolefins may be cited homopolymers or copolymers of alpha olefins or diolefins, such as, for example, ethylene, propylene, butene-1, octene-1, butadiene, and more particularly:

[0154] - homopolymers and copolymers of ethylene, in particular LDPE, HDPE, LLDPE (linear low density polyethylene), VLDPE (very low density polyethylene) and metallocene polyethylene,

[0155] - homopolymers or copolymers of propylene,

[0156] - ethylene / alpha-olefin copolymers such as ethylene / propylene, EPR (abbreviation of ethylene-propylene-rubber) and ethylene / propylene / diene (EPDM),

[0157] - styrene / ethylene-butene / styrene (SEBS), styrene / butadiene / styrene (SBS), styrene / isoprene / styrene (SIS), styrene / ethylene-propylene / styrene (SEPS) block copolymers,

[0158] - copolymers of ethylene with at least one product chosen from salts or esters of unsaturated carboxylic acids such as alkyl (meth)acrylate (for example methyl acrylate), or vinyl esters of saturated carboxylic acids such as vinyl acetate (EVA), the proportion of comonomer being able to reach 40% by weight.

[0159] These polyolefins described above can be grafted, co-polymerized or terpolymerized by reactive units (functionalities), such as carboxylic acid, anhydride, or epoxy functions.

[0160] More particularly, these polyolefins are grafted or co- or terpolymerized by unsaturated epoxides such as glycidyl (meth)acrylate, or by carboxylic acids or the corresponding salts or esters such as (meth)acrylic acid (the latter being able to be neutralized totally or partially by metals such as Zn, etc.) or even by carboxylic acid anhydrides such as maleic anhydride.

[0161] The functionalized polyolefin (B1) can be chosen from the following (co)polymers, grafted with maleic anhydride or glycidyl methacrylate, in which the grafting rate is for example from 0.01 to 5% by weight:

[0162] - PE, PP, copolymers of ethylene with propylene, butene, hexene, or octene containing for example 35 to 80% by weight of ethylene

[0163] - ethylene / alpha-olefin copolymers such as ethylene / propylene, EPR (abbreviation of ethylene-propylene-rubber) and ethylene / propylene / diene (EPDM),

[0164] - styrene / ethylene-butene / styrene (SEBS), styrene / butadiene / styrene (SBS), styrene / isoprene / styrene (SIS), styrene / ethylene-propylene / styrene (SEPS) block copolymers,

[0165] - ethylene and vinyl acetate (EVA) copolymers, containing up to 40% by weight of vinyl acetate,

[0166] - ethylene and alkyl (meth)acrylate copolymers, containing up to 40% by weight of alkyl (meth)acrylate,

[0167] - ethylene vinyl acetate (EVA) and alkyl (meth)acrylate copolymers, containing up to 40% by weight of comonomers.

[0168] A functionalized polyolefin is, for example, a PE / EPR blend, the weight ratio of which can vary widely, for example between 40 / 60 and 90 / 10, said blend being co-grafted with an anhydride, in particular maleic anhydride, according to a grafting rate of, for example, 0.01 to 5% by weight.

[0169] The functionalized polyolefin (B1) may also be chosen from ethylene / propylene copolymers with a majority of propylene grafted with maleic anhydride and then condensed with mono-amine polyamide (or a polyamide oligomer) (products described in EP-A-0342066). The functionalized polyolefin (B1) may also be a co- or terpolymer of at least the following units:

[0170] (1) ethylene,

[0171] (2) alkyl (meth)acrylate or vinyl ester of saturated carboxylic acid and

[0172] (3) anhydride such as maleic anhydride or (meth)acrylic acid or epoxy such as glycidyl (meth)acrylate.

[0173] As examples of functionalized polyolefins of the latter type, the following copolymers may be mentioned, where ethylene preferably represents at least 60% by weight and where the termonomer (the function) represents, for example, from 0.1 to 12% by weight of the copolymer:

[0174] - ethylene / alkyl (meth)acrylate / (meth)acrylic acid or maleic anhydride or glycidyl methacrylate copolymers;

[0175] - ethylene / vinyl acetate / maleic anhydride or glycidyl methacrylate copolymers;

[0176] - ethylene / vinyl acetate or alkyl (meth)acrylate / (meth)acrylic acid or maleic anhydride or glycidyl methacrylate copolymers.

[0177] In the above copolymers, (meth)acrylic acid may be salified with Zn or Li. The term "alkyl (meth)acrylate" in (B1) refers to C1-C8 alkyl methacrylates and acrylates, and may be selected from methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, ethyl-2-hexyl acrylate, cyclohexyl acrylate, methyl methacrylate and ethyl methacrylate.

[0178] Furthermore, the above-mentioned polyolefins (B1) can also be crosslinked by any suitable process or agent (diepoxy, diacid, peroxide, etc.); the term functionalized polyolefin also includes mixtures of the above-mentioned polyolefins with a difunctional reagent such as diacid, dianhydride, diepoxy, etc. capable of reacting with them or mixtures of at least two functionalized polyolefins capable of reacting with each other.

[0179] The above-mentioned copolymers (B1) can be copolymerized in a random or block manner and have a linear or branched structure.

[0180] The molecular weight, MFI index, and density of these polyolefins can also vary widely, as those skilled in the art will appreciate. The MFI index, short for Melt Flow Index, is the melt flow index. It is measured according to ASTM 1238.

[0181] Advantageously, the functionalized polyolefins (B1) are chosen from any polymer comprising alpha olefinic units and units carrying polar reactive functions such as epoxy, carboxylic acid or carboxylic acid anhydride functions. Examples of such polymers include terpolymers of ethylene, alkyl acrylate and maleic anhydride or glycidyl methacrylate such as Lotader® from SK Geocentric or polyolefins grafted with maleic anhydride such as Orevac® from SK Geocentric as well as terpolymers of ethylene, alkyl acrylate and (meth)acrylic acid. Mention may also be made of homopolymers or copolymers of polypropylene grafted with a carboxylic acid anhydride then condensed with polyamides or mono-amino oligomers of polyamide, as described in application EP 0 342 066.

[0182] More specifically, functionalized polyolefins (B1) are:

[0183] - terpolymers of ethylene, alkyl acrylate and maleic anhydride;

[0184] - terpolymers of ethylene, alkyl acrylate and glycidyl methacrylate;

[0185] - polypropylene and polyethylenes grafted with maleic anhydride;

[0186] - copolymers of ethylene and propylene and possibly of diene monomer grafted with maleic anhydride;

[0187] - copolymers of ethylene and octene grafted with maleic anhydride; and their mixture.

[0188] The functionalized polyolefin (B1) is present in a content of between 0 and 20% by weight, preferably between 1 and 10% by weight relative to the total weight of the composition.

[0189] The composition according to the invention may comprise at least one non-functionalized polyolefin (B2).

[0190] A non-functionalized polyolefin (B2) is typically a homopolymer or copolymer of alpha olefins or diolefins, such as, for example, ethylene, propylene, butene-1, octene-1, butadiene. Examples include:

[0191] - homopolymers and copolymers of polyethylene, in particular LDPE, HDPE, LLDPE (linear low density polyethylene), VLDPE (very low density polyethylene) and metallocene polyethylene,

[0192] - homopolymers or copolymers of propylene,

[0193] - ethylene / alpha-olefin copolymers such as ethylene / propylene, EPR (abbreviation of ethylene-propylene-rubber) and ethylene / propylene / diene (EPDM),

[0194] - styrene / ethylene-butene / styrene (SEBS), styrene / butadiene / styrene (SBS), styrene / isoprene / styrene (SIS), styrene / ethylene-propylene / styrene (SEPS) block copolymers,

[0195] - copolymers of ethylene with at least one product chosen from salts or esters of unsaturated carboxylic acids such as alkyl (meth)acrylate (for example methyl acrylate), or vinyl esters of saturated carboxylic acids such as vinyl acetate (EVA), the proportion of comonomer being able to reach 40% by weight and their mixture.

[0196] The above-mentioned copolymers (B2) can be copolymerized in a random or block manner and have a linear or branched structure.

[0197] Advantageously, the non-functionalized polyolefins (B2) are chosen from homopolymers or copolymers of polypropylene and any homopolymer of ethylene or copolymer of ethylene and a higher alpha olefin comonomer such as butene, hexene, octene or 4-methyl-1-pentene. Examples that may be mentioned are PP (PolyPropylene), high-density polyethylenes, medium-density polyethylenes, linear low-density polyethylenes, low-density polyethylenes, very-low-density polyethylenes. These polyethylenes are known to those skilled in the art as being produced using a radical process, using a “Ziegler” type catalysis or, more recently, using a so-called metallocene catalysis. Also preferred are copolymers of ethylene and vinyl acetate (EVA), such as those marketed under the trade name EVATANE® by the Applicant.

[0198] When the composition according to the invention comprises one or more non-functionalized polyolefins, the MFI of (A) and the MFIs of (B1) and (B2) can be chosen from a wide range, however it is recommended to facilitate the dispersion of (B1) and (B2) that the viscosities of (B1) and (B2) are close.

[0199] The non-functionalized polyolefin is present in a content of between 0 and 20% by weight, preferably between 1 and 10% by weight relative to the total weight of the composition.

[0200] Advantageously, the impact modifier can also be a copolymer formed from polyamide blocks and polyether blocks, the polyamide blocks and the polyether blocks being linked by an ester function. These products are described in document FR 2 273 021 and sold under the trade name PEBAX® by the company ARKEMA.

[0201] Polyamide block copolymers (abbreviated below as PA) and polyether block copolymers (abbreviated below as PE) result from the copolycondensation of polyamide blocks with reactive ends with polyether blocks with reactive ends. For example, the following can be reacted:

[0202] - polyether diol, and a polyamide dicarboxylic acid,

[0203] - polyetherdiamine and a polyamide dicarboxylic acid,

[0204] - polyetherdiol and a polyamide diamine. Polyamide blocks with dicarboxylic chain ends originate, for example, from the condensation of polyamide precursors in the presence of a chain-regulating dicarboxylic acid. Polyamide blocks with diamine chain ends originate, for example, from the condensation of polyamide precursors in the presence of a chain-regulating diamine. Thus, the bond between the blocks is either an ester bond or an amide bond. Polymers with PA blocks and PE blocks may comprise a single PA block and a single PE block.

[0205] They can also comprise several PA blocks identical in terms of the structure of the monomer(s) constituting the polyamide and identical PE blocks distributed randomly. Said polymers can be prepared by simultaneous reaction of the PE blocks and the precursors of the PA blocks. A polymer is then obtained having PE blocks and PA blocks of very variable length depending on the moment at which the chain regulator intervenes during the formation of the PA block, but also the different reagents having reacted randomly which are distributed randomly (statistically) along the polymer chain.

[0206] The impact modifier is preferably a polar functional polyolefin.

[0207] In the context of the present invention, the term “polar functional polyolefin” means a functional polyolefin as defined above comprising polar monomers such as vinyl acetates, acrylic or methacrylic acids, acrylates, methacrylates and glycidyl methacrylate or a PEBA, preferably the impact modifier is a PEBA.

[0208] Preferably, composition C comprises less than 15% by weight of apolar functional polyolefin, preferably less than 10% by weight, in particular less than 5% by weight, preferably composition C does not comprise apolar functional polyolefin.

[0209] Preferably, the impact modifier of the invention is a functional polyolefin, preferably a polyolefin (B1) as described above, comprising at least one heteroatom, preferably at least one nitrogen atom or one oxygen atom.

[0210] Preferably, the impact modifier of the invention is a functional polyolefin chosen from copolymers of ethylene with at least one product chosen from salts or esters of unsaturated carboxylic acids such as alkyl (meth)acrylate (for example methyl acrylate), or vinyl esters of saturated carboxylic acids such as vinyl acetate (EVA), the proportion of comonomer being able to reach 40% by weight. The polyamide composition according to the invention can also comprise from 0 to 10% by weight of additives relative to the total weight of the composition, preferably from 0.1 to 10%.

[0211] Preferably, the additives present in the polyamide composition of the invention are chosen from lubricants, organic or inorganic pigments, anti-UV agents, antistatic agents, mineral fillers, such as, for example, talc, silica, calcium carbonate, titanium dioxide, zinc oxide and organic fillers.

[0212] Preferably, the composition according to the invention comprises a plasticizer content of less than 10%, preferably less than 6%, preferably less than 5%, preferably less than 3%, more preferably less than 1%, by weight relative to the total weight of composition C, preferably the composition according to the invention is free of plasticizer, such as BBSA (BenzylButylSulfonAmide).

[0213] The polyamide composition according to the invention may comprise from 0 to 30%, preferably from 1 to 27%, more preferably from 2 to 25%, by weight relative to the total weight of composition C, of ​​at least one current-conducting filler relative to the total weight of the composition.

[0214] The conductive filler may be selected from carbon blacks, graphites, graphenes, carbon nanotubes, and metallic fillers such as metallic fibers or metallic powders. These metallic fillers advantageously include iron or copper.

[0215] Preferably, when the current-conducting filler is carbon black or graphite, it is comprised in a content of 15 to 30%, preferably 18 to 27%, by weight relative to the total weight of composition C. When the current-conducting filler is a filler other than carbon black and graphite, for example graphene, carbon nanotubes, it is comprised in a content of 0.5 to 6%, preferably 1 to 5%, by weight relative to the total weight of composition C.

[0216] In one embodiment, the polyamide composition according to the invention comprises less than 10% by weight, preferably less than 5% by weight, preferably less than 2% by weight, preferably less than 1% by weight, of carbon black and / or black dye, preferably does not comprise carbon black and / or black dye.

[0217] Preferably, the polyamide composition according to the invention comprises less than 5% by weight, preferably less than 2% by weight, preferably less than 1% by weight, of crosslinked material, preferably does not comprise any crosslinked material. Thus and particularly advantageously, the composition C according to the invention is preferably completely heat-meltable, this advantageously allows easy recycling of the composition.

[0218] The following compositions C according to the invention are preferred (the percentages are given by weight relative to the total weight of composition C):

[0219] C1) comprising or consisting of:

[0220] - 34.9 to 79.9% polyamide matrix

[0221] - 20 to 65% reinforcing fiber, preferably glass or carbon fiber, especially glass fibers,

[0222] - 0.1 to 5% additives

[0223] C2) comprising or consisting of:

[0224] - 34.9 to 79.9% polyamide matrix

[0225] - 20 to 65% reinforcing fiber, preferably glass or carbon fiber, including glass fibers

[0226] - 0.1 to 5% additives

[0227] The composition comprises less than 100 ppm, preferably less than 50 ppm, preferably less than 10 ppm, preferably 0 ppm of metal salt, preferably less than 100 ppm, preferably less than 50 ppm, preferably less than 10 ppm, preferably 0 ppm of copper salt.

[0228] C3) comprising or consisting of:

[0229] - 30 to 69.9% polyamide matrix

[0230] - 20 to 50% reinforcing fiber, preferably glass or carbon fiber, including glass fibers

[0231] - 10 to 35% flame retardant, particularly phosphorus

[0232] - 0.1 to 5% additives

[0233] The composition comprises less than 100 ppm, preferably less than 50 ppm, preferably less than 10 ppm, preferably 0 ppm of metal salt, preferably less than 100 ppm, preferably less than 50 ppm, preferably less than 10 ppm, preferably 0 ppm of copper salt.

[0234] C4) comprising or consisting of:

[0235] - 30 to 69.9% polyamide matrix

[0236] - 20 to 50% reinforcing fiber, preferably carbon fiber

[0237] - 10 to 35% flame retardant, particularly phosphorus

[0238] - 1 to 25%, preferably 2 to 15% of a current-carrying filler

[0239] - 0.1 to 5% of additives The composition comprises less than 100 ppm, preferably less than 50 ppm, preferably less than 10 ppm, preferably 0 ppm of metal salt, preferably less than 100 ppm, preferably less than 50 ppm, preferably less than 10 ppm, preferably 0 ppm of copper salt.

[0240] C5) comprising or consisting of:

[0241] - 30 to 69.9% polyamide matrix

[0242] - 20 to 50% of reinforcing fiber, preferably glass fiber or carbon fiber, preferably glass fiber, having an average fiber length of between 300 and 10,000 pm, in particular an average length of between 350 and 5000 pm, in particular an average length of between 400 and 2000 pm.

[0243] - 10 to 35% flame retardant, particularly phosphorus

[0244] - 1 to 25%, preferably 2 to 15% of a current-carrying filler

[0245] - 0.1 to 5% additives

[0246] The composition comprises less than 100 ppm, preferably less than 50 ppm, preferably less than 10 ppm, preferably 0 ppm of metal salt, preferably less than 100 ppm, preferably less than 50 ppm, preferably less than 10 ppm, preferably 0 ppm of copper salt.

[0247] Dielectric fluid

[0248] The dielectric fluid according to the invention preferably comprises one or more compounds chosen from mineral oils and mineral oil derivatives, polyalphaolefins, polyalkylene glycols, silicones, esters with a number-average molar mass of between 1000 and 100,000 g / mol, preferably between 10,000 and 100,000 g / mol, preferably between 20,000 and 100,000 g / mol, preferably between 50,000 and 100,000 g / mol, for example polyol ester, POE, partially fluorinated polymers having a number-average molar mass of 1000 and 100,000 g / mol, preferably between 10,000 and 100,000 g / mol, preferably between 20,000 and 100,000 g / mol, preferably between 50,000 and 100,000 g / mol, for example perfluoropolyethers.

[0249] Preferably, the dielectric fluid according to the invention comprises less than 5% by weight of halogenated compound, preferably does not comprise any halogenated compound. In the context of the present invention, the term halogenated compound means a compound comprising at least one halogen atom.

[0250] Preferably, the dielectric fluid according to the invention comprises one or more compounds chosen from mineral oils and mineral oil derivatives, polyalphaolefins, polyalkylene glycols, silicones, esters with a number-average molar mass of between 1000 and 100,000 g / mol, preferably between 10,000 and 100,000 g / mol, preferably between 20,000 and 100,000 g / mol, preferably between 50,000 and 100,000 g / mol, for example polyol ester, POE.

[0251] Preferably, the mineral oils and mineral oil derivatives have a number average molar mass of between 1000 and 100,000 g / mol, preferably between 20,000 and 100,000 g / mol, more preferably between 50,000 and 100,000 g / mol.

[0252] Preferably, the dielectric fluid according to the invention has a density at 23°C of between 0.3 and 1.5, preferably between 0.5 and 1.1, advantageously between 0.7 and 1.05, more preferably between 0.8 and 1. The density measurement is carried out according to standard ISO 1675:2022 at 23°C.

[0253] Preferably, the dielectric fluid according to the invention has a kinematic viscosity at 40°C of between 1 and 35 mm 2 / s, preferably between 1.5 and 15 mm 2 / s, especially between 2 and 10 mm 2 / s and / or a kinematic viscosity at 100°C between 0.01 and 5 mm 2 / s, preferably between 0.1 and 4 mm 2 / s, preferably between 0.5 and 3 mm 2 / s, more preferably between 0.8 and 2.5 mm 2 / s and / or a kinematic viscosity at 25°C between 5 and 150 mm 2 / s, preferably between 10 and 100 mm 2 / s. Kinematic viscosity is measured according to ISO 3104:2020.

[0254] Preferably, the conductivity of the dielectric fluid is less than 1 pS / cm, preferably less than 0.1 pS / cm, in particular less than 0.01 pS / cm. The resistivity of the fluid is measured according to the standard DI N IEC 60247 which makes it possible to calculate the conductivity. It is understood that this conductivity corresponds to the conductivity of the dielectric fluid before any use and before aging.

[0255] Preferably, the dielectric fluid according to the invention:

[0256] - comprises one or more compounds chosen from mineral oils and mineral oil derivatives, polyalphaolefins, polyalkylene glycols, silicones, esters, for example polyol ester, POE, partially fluorinated polymers of low molecular weight, for example perfluoropolyethers;

[0257] - a density less than 1.5, preferably less than 1;

[0258] - a kinematic viscosity at 40°C between 1 and 35 mm 2 / s, preferably between 1.5 and 15 mm 2 / s, especially between 2 and 10 mm 2 / s and / or a kinematic viscosity at 100°C between 0.01 and 5 mm 2 / s, preferably between 0.1 and 4 mm 2 / s, preferably between 0.5 and 3 mm 2 / s, more preferably between 0.8 and 2.5 mm 2 / s and / or a kinematic viscosity at 25°C between 5 and 150 mm 2 / s, preferably between 10 and 100 mm 2 / s.

[0259] Mineral oils are preferably mixtures obtained from the distillation of fossil fuels such as petroleum, coal, etc. Mineral oils are composed of hydrocarbons and mainly C15 to C40 alkanes.

[0260] Preferably, the dielectric fluid is free of halogen, water and glycol ether.

[0261] Specific dielectric fluids include ExxonMobil Mobil EV ThermElite 701® (alkylnaphthenic hydrocarbon basestock blend, PAO & esters), M&l Mivolt DF7® (polyol ester blend), Engineered FLuids Ampcool AC-110® (hydrocarbon basestock blend & esters) and Shell Diala S4 ZX-I® (hydrocarbon basestock blends), as well as Croda Xenitron 3221® (ester blends), Total EnergiesEco Friendly® (biomass hydrocarbon basestock blends) and Total Energies Cell Shield® (synthetic oil blends).

[0262] The dielectric fluid according to the invention has, before contact with the elements to be cooled, for example the battery cells, a temperature below 40°C, preferably below 30°C, for example between -10 and 30°C. The dielectric fluid according to the invention has, after contact with the elements to be cooled, for example the battery cells, a temperature between 40 and 110°C, preferably between 40 and 90°C, preferably between 40 and 65°C, advantageously between 40 and 60°C, preferably between 40 and 50°C.

[0263] Elements according to the invention

[0264] Preferably, the element according to the invention comprises at least one inlet and at least one outlet allowing the circulation of the dielectric fluid.

[0265] In one embodiment, the element is a housing or module, preferably a housing or module for the direct cooling of battery cells, said battery cells being in direct contact with the dielectric fluid in said housing or module. The housing according to the invention may comprise from 1 to 20,000 battery cells, preferably from 5 to 10,000 battery cells, in particular from 10 to 5,000 battery cells, advantageously from 20 to 1,000 battery cells. In one embodiment, the element is an element for the distribution of the dielectric fluid, for example a valve or a valve, and has one inlet and at least two outlets or at least two inlets and at least one outlet.

[0266] In yet another embodiment, the element according to the invention is a connector, allowing for example to link pipes together or to connect a pipe to the inlet of a box, a reservoir, a valve, etc.

[0267] In yet another embodiment, the element according to the invention is a nozzle, in particular a nozzle allowing the vaporization of the dielectric fluid in a housing (or module) comprising the battery cells.

[0268] Cooling circuit and device

[0269] The present application also relates to a battery cell cooling circuit using a dielectric fluid comprising at least one element according to the invention in the form of a housing or module, comprising at least one inlet and at least one outlet, allowing the circulation of said dielectric fluid comprising battery cells and a dielectric fluid, the dielectric fluid being as defined above.

[0270] Said cooling circuit according to the invention may also comprise at least two pipes for transporting said dielectric fluid connected directly or using a connector, to the inlet and outlet of the housing or module. Preferably, the pipe comprises at least one layer, preferably consists of a layer, consisting of a composition comprising from 50 to 99.9% by weight relative to the total weight of the composition of a polyamide matrix preferably having an average C / N ratio greater than or equal to 7 and is free of fibers and reinforcing fillers. The dielectric fluid entering the housing is a cold fluid and the dielectric fluid leaving the housing is a hot fluid.

[0271] Preferably, the connector is made of a polyamide composition comprising from 35 to 85% by weight of a polyamide matrix preferably having an average C / N ratio greater than or equal to 7 and from 15 to 65% by weight of reinforcing fibers or fillers. Preferably, the connector is an element according to the invention.

[0272] The cooling circuit according to the invention may also comprise at the inlet of the housing a nozzle allowing the cells to be sprayed with the dielectric fluid. Preferably, the nozzle is made of a polyamide composition comprising from 35 to 85% by weight of a polyamide matrix preferably having an average C / N ratio greater than or equal to 7 and from 15 to 65% by weight of reinforcing fibers or fillers.

[0273] The present invention also relates to a cooling device for battery cells using a dielectric fluid comprising:

[0274] - at least one housing (BX) adapted to receive battery cells and provided with an inlet and an outlet allowing the circulation of a dielectric fluid in said housing in direct contact with the battery cells;

[0275] - a dielectric fluid included in said housing (BX);

[0276] - said housing (BX) being made of a polyamide C composition according to the invention;

[0277] - said dielectric fluid being as described above.

[0278] The housing (BX), the polyamide composition, the battery, the battery cells and the dielectric fluid are as defined above.

[0279] The device according to the invention preferably comprises, upstream of the housing (BX), at least one pipe in which said dielectric fluid circulates towards the housing (BX), and downstream of the housing (BX), at least one pipe according to the invention in which said dielectric fluid circulates from the housing (BX). Preferably, the pipe comprises at least one layer, preferably consists of a layer, consisting of a composition comprising from 50 to 99.9% by weight relative to the total weight of the composition of a polyamide matrix preferably having an average C / N ratio greater than or equal to 7 and is free of fibers and reinforcing fillers. The dielectric fluid entering the housing is a cold fluid and the dielectric fluid leaving the housing is a hot fluid.

[0280] The pipes can be connected to the inlet and / or outlet of the housing (BX) directly or using a connector, the connector preferably being made of a polyamide composition comprising from 35 to 85% by weight of a polyamide matrix preferably having an average C / N ratio greater than or equal to 7 and from 15 to 65% by weight of reinforcing fibers or fillers.

[0281] In one embodiment, the inlet of the housing (BX) is equipped with a nozzle, connected to the pipe, allowing the cells to be sprayed with the dielectric fluid. Preferably, the nozzle is made of a polyamide composition comprising from 35 to 85% by weight of a polyamide matrix preferably having an average C / N ratio greater than or equal to 7 and from 15 to 65% by weight of reinforcing fibers or fillers.

[0282] In one embodiment, the device may comprise a reservoir of dielectric fluid, said reservoir preferably being according to the invention and being connected to the other elements of the device by the pipes according to the invention directly or via connectors as defined above.

[0283] In one embodiment, the hot fluid from the housing (BX) is transported to a cooling system. In one embodiment, the cold fluid entering the housing (BX) comes from a reservoir, preferably a reservoir according to the invention. In this embodiment, upstream, the pipe connects the reservoir to the housing (BX) either directly or via connectors as defined above.

[0284] In one embodiment, the device comprises a plurality of pipes connected to each other using connectors. The connectors are preferably made of a polyamide composition comprising from 35 to 85% by weight of a polyamide matrix preferably having an average C / N ratio greater than or equal to 7 and from 15 to 65% by weight of reinforcing fibers or fillers.

[0285] In the context of the present invention, the term “cold dielectric fluid” means a dielectric fluid whose temperature is less than 40°C, preferably less than 30°C, for example between -10 and 30°C, and the term “hot dielectric fluid” means a dielectric fluid whose temperature is greater than 40°C, preferably between 40 and 110°C, preferably between 40 and 90°C, preferably between 40 and 65°C, advantageously between 40 and 60°C, preferably between 40 and 50°C.

[0286] The present application also relates to a device for the direct cooling of battery cells by a dielectric fluid comprising:

[0287] - A dielectric fluid;

[0288] - Optionally a tank element (R1);

[0289] - At least one housing (BX) according to the invention adapted to receive battery cells and provided with an inlet and an outlet allowing the circulation of said dielectric fluid in said housing in direct contact with the battery cells;

[0290] - Upstream of the at least one housing (BX) at least one element (E1), preferably according to the invention, for distributing the dielectric fluid coming from the reservoir to the housings (BX), the element (E1) comprising an inlet for the dielectric fluid and x outlets connected to the housings (BX), x corresponding to the number of housings (BX), each of the outlets being connected to a housing (BX);

[0291] - Downstream of the housings (BX) at least one element (E2), preferably according to the invention, for recovering the dielectric fluid coming from the housings (BX), the element (E2) comprising y inlets for the dielectric fluid and z outlets, y corresponding to the number of housings (BX) connected to the element (E2) and z corresponding to the number of cooling systems (S1), each of the inlets being connected to a housing (BX) and each of the outlets being connected to at least one cooling system (S1);

[0292] - At least one cooling system (S1), preferably a radiator, allowing the cooling of the dielectric fluid coming from the element (E2);

[0293] - elements, in particular in the form of a pipe in which said dielectric fluid circulates between the reservoir (R1), the element (E1), the boxes (BX), the element (E2) and the cooling system (S1);

[0294] - The dielectric fluid being as defined according to the invention.

[0295] Preferably z equals 1.

[0296] Preferably, the pipes and / or tank (E1) and (E2) comprise at least one layer, preferably consist of a layer, consisting of a composition comprising from 50 to 99.9% by weight relative to the total weight of the composition of a polyamide matrix preferably having an average C / N ratio greater than or equal to 7 and is free of fibers and reinforcing fillers.

[0297] The boxes (BX) are preferably boxes suitable for receiving battery cells and the dielectric fluid.

[0298] Elements (E1) and (E2) are preferably valves or connectors.

[0299] Preferably, the pipes consist of several pipes connected together by connectors. Preferably, the pipes are connected to the inlets and / or outlets of the boxes (BX) and elements (E1) and (E2) directly or using connectors.

[0300] In one embodiment, the inputs of the boxes (BX) are equipped with a nozzle allowing the spraying of the dielectric fluid directly onto the battery cells.

[0301] The connectors and / or nozzles are preferably elements according to the invention.

[0302] In one embodiment, the device according to the invention is included in a container comprising an inlet and an outlet each equipped with a pipe, or a plurality of pipes connected together by connectors preferably according to the invention, and allowing the circulation of said dielectric fluid. Preferably, said pipes comprise at least one layer, preferably consist of a layer, consisting of a composition comprising from 50 to 99.9% by weight relative to the total weight of the composition of a polyamide matrix preferably having an average C / N ratio greater than or equal to 7 and is free of fibers and reinforcing fillers.

[0303] In the context of the present invention, connector is understood to mean an interface part allowing the connection between two pipes, the connection between a pipe and a housing, the connection between a pipe and any other element of the device or circuit according to the invention. Preferably, the connectors according to the invention are injected parts, advantageously comprising a polyamide and reinforcing fibers.

[0304] The device or circuit of the invention may comprise at least one package, preferably at least 2 packages, preferably at least 6 packages, preferably at least 10 packages, preferably at least 16 packages, for example from 1 to 50 packages, preferably from 1 to 26 packages, preferably from 1 to 16 packages. Preferably, the number of packages is an even number.

[0305] The present invention also relates to the use of a composition for implementation in the form of an element of a cooling circuit using a dielectric fluid, the element being in contact with the dielectric fluid, and in which:

[0306] - the composition comprises: o from 35 to 85% by weight of a polyamide matrix having an average C / N ratio greater than or equal to 7; o from 15 to 65% by weight of fillers or reinforcing fibers;

[0307] - the dielectric fluid is liquid at atmospheric pressure at 23°C and comprises less than 10% by weight of water and glycol ether.

[0308] Preferably, the dielectric fluid is free of halogen, water and glycol.

[0309] The element, the polyamide C composition, and the dielectric fluid are as defined above.

[0310] Manufacturing process of the elements

[0311] Depending on the size of the fibers, the elements according to the invention, preferably the housings according to the invention, can be produced using different techniques.

[0312] When the fibers are short or in the form of long fiber compounds (LFT), the element according to the invention, preferably the housing according to the invention, can be obtained by injection, extrusion, coextrusion, hot pressing, multi-injection from at least one composition as defined above. When the fibers are long or continuous, the element according to the invention can be produced by different techniques chosen from: pultrusion, filament winding, thermocompression, infusion molding, resin transfer molding (RTM), structured reaction injection molding (S-RIM) or injection-compression molding. A particular closed-mold technique is RTM or S-RIM or injection-compression. The term "resin" in RTM is identified here with the composition according to the invention without the reinforcing fibers.

[0313] According to a particular embodiment, the manufacturing method may comprise

[0314] - a step of applying the reinforcing fibers in the mold, then

[0315] - at least one step of impregnating said fibers with a precursor composition of composition C according to the invention.

[0316] Preferably, the element according to the invention is obtained by injection.

[0317] Circuit

[0318] The present invention also relates to a cooling circuit for an electric or hybrid motor vehicle battery, comprising a main loop for circulating a dielectric fluid provided with means for circulating the dielectric fluid in the main loop.

[0319] Further, the main loop is connected to the element as previously described.

[0320] According to a characteristic of the invention, the circuit may comprise at least one secondary loop connected to the main loop, the secondary loop(s) being connected to the passenger compartment of the motor vehicle and / or to an electronic circuit connected to an electric motor of the motor vehicle and / or to an internal combustion engine of the motor vehicle, when the motor vehicle is of the hybrid type.

[0321] Advantageously, the circuit may comprise a control device configured to control the heat transfer from the main loop to the at least one secondary loop as defined previously.

[0322] Preferably, the boxes according to the invention comprising the battery cells are mounted in series or in parallel.

[0323] The circuit according to the invention preferably comprises:

[0324] - A cooling system

[0325] - Optionally a connector

[0326] - At least one pipe allowing the fluid to enter the housing

[0327] - Optionally an injected connector - At least one housing containing some or all of the battery cells and comprising dielectric fluid cooling the battery cells by spraying or immersion.

[0328] - Optionally an injected connector

[0329] - At least one pipe allowing the fluid to return to the cooling system.

[0330] The housings and connectors are preferably made of composition C according to the invention.

[0331] The invention will be explained in more detail in the following examples.

[0332] [Examples]

[0333] Unless otherwise stated, percentages are expressed by weight relative to the total weight of the composition.

[0334] The evolution of the properties of different elements consisting of a composition C according to the invention before and after soaking in the fluids Mobil EV therm Elite 701® from the company EXXON MOBIL (Table 1), Ampcool AC-110® from the company Engineered fluids (Table 2), Diala S4 ZX-I® from the company Shell (Table 3), after 168 hours at a temperature of 130°C was measured. The fluids contain 500 ppm of water.

[0335] Tensile tests on “1A” dumbbells were carried out at 23°C according to ISO 527 to quantify the differences in properties before and after aging. The evolution of stress and elongation at break for different comparative compositions and according to the invention are shown below.

[0336] The “1A” type dumbbells were made by injection molding for tensile tests. The following parameters were used:

[0337] - ENGEL VICTORY 500 hydraulic press, 160T

[0338] - Injection temperature (feed / nozzle): 230C / 250C

[0339] - Mold temperature: 40°C

[0340] - Holding time: 20s

[0341] - Material holding pressure: 622 bars

[0342] - Cooling time: 15 s

[0343] Irganox 245® and irgafos 168® are marketed by BASF.

[0344] The Orevac IM800® is marketed by SK geocentric.

[0345] The following compositions were tested: El 1: A composition comprising 69.4% by weight of polyamide 11, 30% by weight of glass fiber, 0.3% by weight of Irganox 245® and 0.3% by weight of irgafos 168®

[0346] EC 1 (comparative): A composition comprising 89.4% by weight of polyamide 6, 10% by weight of Orevac IM800® functional polyolefins,

[0347] 0.3% by weight of Irganox 245® and 0.3% by weight of irgafos 168®.

[0348] El 2: a composition C comprising 69.4% by weight of polyamide 12, 30% by weight of glass fiber, 0.3% by weight of Irganox 245® and 0.3% by weight of irgafos 168®. - EC 2: A polypropylene composition (Hostalen® PP H 1886)

[0349] EC 3: A thermoplastic vulcanizate composition (Santoprene® 101.87)

[0350] Table 1 Table 2 Table 3

Claims

Claims 1. Use of at least one element in a cooling circuit using at least one dielectric fluid, wherein: said dielectric fluid is liquid at atmospheric pressure at 23°C and comprises less than 10% by weight of water and glycol ether; the element is made of a polyamide C composition comprising: o from 35 to 85% by weight of a polyamide matrix having an average C / N ratio greater than or equal to 7; o from 15 to 65% by weight of reinforcing fibers or fillers, said element being in direct contact with the dielectric fluid.

2. Use according to claim 1, in which the polyamide matrix has an average C / N ratio greater than or equal to 8, preferably greater than or equal to 9, preferably between 9 and 12.

3. Use according to claim 1 or 2, in which composition C has an inherent viscosity of between 1 and 1.8, preferably between 1.1 and 1.6, more preferably between 1.15 and 1.

4.

4. Use according to any one of the preceding claims, in which the dielectric fluid comprises one or more compounds chosen from mineral oils and mineral oil derivatives, polyalphaolefins, polyalkylene glycols, silicones, esters with a number-average molar mass of between 1000 and 100,000 g / mol, for example polyol ester, POE, partially fluorinated polymers having a number-average molar mass of 1000 and 100,000 g / mol, for example perfluoropolyethers.

5. Use according to any one of the preceding claims, in which the dielectric fluid has a density measured according to the ISO 1675:2022 standard of between 0.3 and 1.5, preferably between 0.5 and 1.1, advantageously between 0.7 and 1.05, more preferably between 0.8 and 1.

6. Use according to any one of the preceding claims, in which the dielectric fluid has a kinematic viscosity at 40°C of between 1 and 35 mm 2 / s, preferably between 1.5 and 15 mm 2 / s, especially between 2 and 10 mm 2 / s and / or a kinematic viscosity at 100°C between 0.01 and 5 mm 2 / s, preferably between 0.1 and 4 mm 2 / s, preferably between 0.5 and 3 mm 2 / s, more preferably between 0.8 and 2.5 mm 2 / s and / or a kinematic viscosity at 25°C between 5 and 150 mm 2 / s, preferably between 10 and 100 mm 2 / s, the kinematic viscosity being measured according to ISO 3104:2020.

7. Use according to any one of the preceding claims, in which composition C further comprises from 0.01 to 1.5%, preferably from 0.05 to 0.5%, more preferably from 0.1 to 0.4%, by weight of a heat stabilizer relative to the total weight of composition C.

8. Use according to any one of the preceding claims, wherein the composition further comprises: From 10 to 35%, preferably from 15 to 25%, by weight of a flame retardant, preferably a non-halogenated flame retardant, preferably a phosphorus-containing flame retardant; and / or From 1 to 35% by weight, preferably from 2 to 10% by weight of at least one impact modifier; and / or From 0.5 to 30% by weight of at least one current-conducting filler; and / or From 0.1 to 10% by weight of at least one additive.

9. Use according to any one of the preceding claims, wherein composition C comprises a plasticizer content of less than 10%, preferably less than 6%, preferably less than 5%, preferably less than 3%, preferably less than 1%, by weight, preferably composition C is free of plasticizer, such as BBSA (N-Butyl Benzene Sulfonamide).

10. Use according to any one of the preceding claims, in which the element comprises at least one inlet and at least one outlet allowing the circulation of the dielectric fluid.

11. Use according to any one of claims 1 to 10, in which the element is a housing or module for direct cooling. of battery cells, said battery cells being in contact with the dielectric fluid in said housing or module.

12. Use according to any one of claims 1 to 10, wherein the element is an element for distributing the dielectric fluid, for example a valve or a valve, and having an inlet and at least two outlets or comprising at least two inlets and one outlet.

13. Device for the direct cooling of battery cells using a dielectric fluid comprising: at least one housing (BX) adapted to receive battery cells and provided with an inlet and an outlet allowing the circulation of a dielectric fluid in said housing in direct contact with the battery cells; A dielectric fluid included in said housing (BX); Said housing (BX) being made of a composition described according to any one of claims 1 to 3 and 7 to 9; The dielectric fluid being as defined according to any one of claims 1, 4 to 6.

14. Device for the direct cooling of battery cells by a dielectric fluid comprising: A dielectric fluid; Optionally at least one element a tank (R1); - At least one housing (BX) adapted to receive battery cells and provided with an inlet and an outlet allowing the circulation of a dielectric fluid in said housing in direct contact with the battery cells; Upstream of the box(es) (BX) at least one element (E1) for distributing the dielectric fluid to the box(es) (BX), the element (E1) comprising an inlet for the dielectric fluid and x outlets connected to the boxes (BX), x corresponding to the number of boxes (BX), each of the outlets being connected to a box (BX); - Downstream of the housings (BX) at least one element (E2), preferably according to the invention, for recovering the dielectric fluid coming from the housings (BX), the element (E2) comprising y inlets for the dielectric fluid and z outlets, y corresponding to the number of housings (BX) connected to the element (E2) and z corresponding to the number of cooling systems (S1), each of the inlets being connected to a housing (BX) and each of the outputs being connected to at least one cooling system (S1); at least one cooling system (S1), preferably a radiator, allowing the cooling of the dielectric fluid coming from the element (E2); elements, in particular in the form of a pipe in which said dielectric fluid circulates between the reservoir (R1), the element (E1), the housings (BX), the element (E2) and the cooling system (S1); the housing(s) (BX) and / or, preferably and, the elements (E1) and (E2) being made of a composition described according to any one of claims 1 to 3 and 7 to 9; The dielectric fluid being as defined according to any one of claims 1, 4 to 6.

15. Device according to claim 14, in which the inlets of the boxes (BX) are equipped with a nozzle allowing the spraying of the dielectric fluid directly onto the battery cells, preferably the nozzle is made of a polyamide composition comprising from 35 to 85% by weight of a polyamide matrix preferably having an average C / N ratio greater than or equal to 7 and from 15 to 65% by weight of reinforcing fibers or fillers.

16. Device according to any one of claims 14 to 15, in which the pipes are connected to the inlets and / or outlets of the housings (BX), of the elements (E1) and (E2) directly or using connectors, preferably made of a polyamide composition comprising from 35 to 85% by weight of a polyamide matrix preferably having an average C / N ratio greater than or equal to 7 and from 15 to 65% by weight of reinforcing fibers or fillers.

17. Device according to any one of claims 14 to 16 included in a container comprising an inlet and an outlet each equipped with a pipe, or a plurality of pipes connected together by connectors, and allowing the circulation of said dielectric fluid.

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