Thermoplastic elastomer composition and article, such as hose, comprising same

Abstract

The present invention relates to a thermoplastic elastomer composition which can be used in particular for single-layer (1) or multi-layer hoses, and to an elastomer or elastomer-textile or metal composite article comprising said composition. The present invention relates to a composition comprising: (i) at least one elastomer, (ii) at least one polyolefin comprising a recycled polyolefin fraction and optionally a raw polyolefin fraction, (iii) a reinforcing filler, (iv) a plasticizing system, and (v) an antioxidant system, according to the invention, the composition comprising, in parts by mass:-greater than 35% of the at least one polyolefin, and less than 30% of the plasticizing system.

Description

Technical Field

[0001] The present invention relates to thermoplastic elastomer compositions, particularly useful in single-layer or multi-layer hoses, and elastomer or elastomer-textile or metal composite articles comprising the compositions. The present invention is particularly suitable for single-layer or multi-layer hoses, such as those used in the cooling circuits of batteries or electric motors in hybrid or electric vehicles. In particular, the present invention generally relates to any elastomer or composite article comprising an elastomeric material (including but not limited to gaskets, vibration dampers, and any other elastomeric component, such as for battery packs or data processing centers), which may be used in land (automobile or rail), water, air, or space vehicles, as well as in any industrial or residential facility. Background Art

[0002] In a known manner, the hoses for the cooling circuit of a motor vehicle are most often based on one or more rubbers and may be:

[0003] - Single-layer type, as for example in document FR 3°130°922A1 in the name of the Applicant, which proposes a method for 5 A hose without a reinforcement core for conveying cooling fluids at temperatures of 100° C. and at most 110° C., consisting of a rubber layer based on ethylene-propylene-diene terpolymer (EPDM), or

[0004] - Most often of the multilayer type, comprising an inner rubber layer designed to come into contact with the cooling fluid, a reinforcing core covering the inner layer, for example a textile reinforcing core, and at least one outer rubber layer covering the reinforcing core, as in document US Pat. No. 11,833,787 B2 in the name of the Applicant, which describes an inner layer based on EPDM, a textile reinforcing core, an outer layer based on ethylene-vinyl acetate (EVA) rubber and an intermediate layer based on a mixture of EPDM rubber with EVA rubber or with acrylic rubber of the polyacrylate (ACM) or ethylene-acrylate (AEM) type.

[0005] Recently, attempts have been made to use thermoplastic elastomers (TPE) instead of the above-mentioned rubbers to manufacture liquid transport hoses, as described, for example, in document WO 2022 / 234351 A1, which discloses the use of a TPE composed of the following to manufacture at least one layer of reinforced or complex hoses:

[0006] (A) 30-80% by weight of a polymer matrix consisting of 10-35% of a first thermoplastic fraction (A1) and 20-45% of a second elastomeric fraction (A2) present in a TPE;

[0007] (B) 30-55% by weight of at least one plasticizer;

[0008] (C) 0-30% of at least one filler;

[0009] (D) 0-10% of at least one additive;

[0010] The TPE has a Shore A hardness of 50-85, a PCR (post-consumer recycling) recycled material mass ratio of 50% or greater, and the TPE is present in at least 90% of the total weight of the hose.

[0011] The main disadvantage of the hoses proposed in WO 2022 / 234351 A1 is the fact that they are specifically designed to form irrigation, watering or water delivery hoses in swimming pools or spas and are not suitable for the operating conditions of the cooling circuit of an electric motor or battery of a car (see in particular the TPE-S and TPV tested in Tables 3 and 6 of WO 2022 / 234351 A1, respectively, without reinforcing fillers such as carbon black, which have breaking stress values ​​that are far below the minimum value required for a single-layer hose for such a cooling circuit).

[0012] In fact, such cooling circuits require that the hoses resist electrochemical degradation, both mechanically and chemically, in contact with the pressurized cooling fluid (usually glycol water) and its external environment (usually hot air). These requirements must characterize the same layer in the case of single-layer hoses. In particular, the hoses used in such cooling circuits should exhibit satisfactory fracture properties even after long-term thermal aging in contact with air and glycol water.

[0013] A further disadvantage of the hose proposed in WO 2022 / 234351 A1 is the relatively high amount of plasticizer used. SUMMARY OF THE INVENTION

[0014] An object of the present invention is to provide a thermoplastic elastomer composition, in particular capable of forming a single-layer hose for the cooling circuit of a battery or an electric motor of an electric or hybrid electric vehicle, said hose particularly remedying the aforementioned drawbacks without impairing its extrudability or its rheological properties and having mechanical properties sufficient to be able to withstand chemically and mechanically prolonged conditions of temperature and pressure suitable for the circulation of cooling fluids and heat aging resistance in glycol water and air.

[0015] This object has been achieved in that the Applicant has surprisingly found that if, in a thermoplastic elastomer composition, the elastomer is combined with a sufficiently high amount of polyolefin containing a recycled fraction in the presence of a sufficiently reduced amount of a plasticizing system, a composition can be obtained which, by means of a reinforcing filler and an antioxidant system, is particularly well suited for forming the inner and / or outer layer of a single-layer hose or a multilayer hose for the aforementioned cooling circuit, in particular having satisfactory rheological, extrudability and flexibility properties and mechanical breaking properties even after the described heat ageing in aqueous glycol solution and air, and therefore having satisfactory long-lasting dynamic performance in this cooling circuit.

[0016] More precisely, the thermoplastic elastomer composition according to the present invention comprises:

[0017] (i) at least one elastomer,

[0018] (ii) at least one polyolefin comprising a recycled polyolefin fraction and optionally a virgin polyolefin fraction,

[0019] (iii) reinforcing fillers,

[0020] (iv) a plasticizing system, and

[0021] (v) antioxidant system,

[0022] And the composition comprises by mass fraction:

[0023] - greater than 35% of said at least one polyolefin, and

[0024] - Less than 30% of said plasticizing system.

[0025] It should be noted that this combination of high and conversely reduced amounts, respectively, of at least partially recycled polyolefin and of plasticizing system (which overcomes the technical prejudices of the person skilled in the art represented by the aforementioned WO 2022 / 234351 A1) makes it particularly advantageous to simultaneously impart to the extruded composition satisfactory rheological properties, extrudability and further mechanical properties that can even be improved after heat aging, compared to the mechanical properties of a reference thermoplastic elastomer composition having a similar formulation but in which the at least one polyolefin is completely virgin (i.e. not at least partially recycled).

[0026] The composition according to the invention is therefore particularly well suited for forming, by way of example and without limitation, inner and / or outer layers of not only single-layer hoses but also multi-layer hoses, as well as gaskets or anti-vibration devices.

[0027] It should also be noted that the thermoplastic elastomer composition according to the invention, which differs from the rubber compositions usually used for cooling circuit hoses, has the advantage, inter alia, that it can be easily shaped (for example by extrusion) like a thermoplastic composition. Detailed Description of the Invention

[0029] "Elastomeric thermoplastic composition" in this specification refers to a TPE material preferably belonging to the family of thermoplastic vulcanizates (TPVs), even though the following may be used instead:

[0030] - unvulcanized olefinic TPE (TPE-O or TPO), for example derived from one or more polyolefins (for example polyethylene and propylene) and a diene or non-diene elastomer (for example chosen from EPDM, copolymers of ethylene and at least one linear or branched α-olefin having 3 to 20 carbon atoms, such as ethylene-propylene EPM copolymers or octene-ethylene POE copolymers), or even

[0031] - Some styrene TPEs (TPE-S or TPS) derived from olefins (e.g., ethylene, propylene, or butylene), for TPS, such as SEBS blocks for polystyrene-b-poly(ethylene-butylene)-b-polystyrene, SEPS for polystyrene-b-poly(ethylene-propylene)-b-polystyrene, or SEEPS for polystyrene-b-poly(ethylene-ethylene / propylene)-b-polystyrene.

[0032] In general, it will be noted that the combination of the above ingredients (i) to (v) makes it possible to impart satisfactory mechanical properties to the composition according to the invention, including secant modulus, Shore A hardness, breaking stress and breaking elongation, each sufficiently high, making it possible, in the first embodiment of the invention, to form a composite material having a surface area of ​​not more than 3.0×10 5 Single-layer hoses for conveying fluids at pressures of 100 Pa and temperatures not exceeding 120° C., such as cooling fluids for low-pressure, low-temperature cooling circuits for batteries or electric motors of hybrid or electric vehicles. As will be described in detail below, these advantageous properties of the composition according to the invention also make it useful in multi-layer hoses according to the second embodiment of the invention, which may incorporate a reinforcing core.

[0033] As the elastomer(s) that can be used in the composition of the TPV type according to the invention, mention may be made, without limitation, of diene or non-diene elastomers in a mass fraction of 10% to 40% (inclusive) of the elastomer(s) in the composition, preferably chosen from:

[0034] -EPDM,

[0035] - homopolymers or copolymers of butadiene and / or isoprene (for example polybutadiene BR, polyisoprene IR) and optionally further vinylaromatic comonomers (for example styrene for SBR), acrylonitrile (for example for NBR rubbers) or branched α-olefins such as isobutylene (for example for butyl IIR rubbers),

[0036] - copolymers of ethylene and at least one linear or branched α-olefin having 3 to 20 carbon atoms, such as EPM or POE, and

[0037] - Acrylic rubbers of the polyacrylate (ACM) or polyacrylate polyethylene (AEM) type.

[0038] Advantageously, as elastomers that can be used in the TPV type compositions according to the invention, ethylene interpolymers (copolymers or terpolymers, such as EPDM, EPM, POE or AEM) can be used, wherein the ethylene is biobased, for example of vegetable origin (for example derived from sucrose).

[0039] According to a preferred embodiment of the TPV composition of the present invention, at least one EPDM is used as the elastomer, the mass fraction of the at least one elastomer in the composition being 15% to 25% (inclusive). Furthermore, the at least one EPDM is then advantageously not oil-extended and may have:

[0040] - The mass ratio of units derived from ethylene is 40-50%, the mass ratio of non-conjugated dienes (such as ethylidene norbornene, ENB) is 8-10%, and preferably

[0041] - Mooney viscosity ML (1+4) at 125°C is 55-70.

[0042] Advantageously, the TPE type composition according to the invention (ie including TPS, TPO and TPV) may comprise greater than 25% by mass, preferably 28% to 50%, for example 30% to 45% (limited values ​​included) of said recycled polyolefin fraction.

[0043] In the present description, the “recycled polyolefin fraction” of the TPE-type composition (e.g. TPS, TPO or TPV) according to the present invention refers to one or more polyolefins that are each non-virgin, i.e. each derived from “PIR” or “PCR” type recycling (i.e. post-industrial (PIR) or post-consumer (PCR) type recycled polyolefin material), or each obtained by grinding in an extruder (e.g. a twin-screw extruder) and then regenerated.

[0044] It should be noted that the at least one polyolefin of the TPE-type composition according to the present invention (e.g., TPS, TPO, or TPV) may comprise a virgin polyolefin portion in a mass fraction ranging from 0% to 50% (inclusive), preferably greater than 0% and less than or equal to 40% in the composition, depending on the recycling or regeneration process implemented to obtain the recycled polyolefin portion. Furthermore, the virgin polyolefin portion may comprise the same polyolefin as the recycled polyolefin portion, or another polyolefin.

[0045] Advantageously, the TPE type composition according to the invention (for example TPS, TPO or TPV) may comprise, by weight, greater than 10%, preferably between 15% and 35% (values ​​inclusive) of said virgin polyolefin fraction.

[0046] Likewise advantageously, the TPE-type composition according to the invention (for example TPS, TPO or TPV) may comprise, in total mass fraction, 40% to 70%, preferably 50% to 68%, for example 55% to 65% (limited values) of said recycled polyolefin fraction and said virgin polyolefin fraction.

[0047] According to another general feature of the TPE-type composition (e.g., TPS, TPO, or TPV) of the present invention, the at least one polyolefin may comprise a homopolymer or interpolymer (e.g., a random, segmented, or block copolymer) of at least one aliphatic or cycloaliphatic α-olefin (e.g., but not limited to propylene or butene), including interpolymers of ethylene and at least one α-olefin (e.g., propylene).

[0048] According to an exemplary embodiment of the TPE type composition (e.g. TPS, TPO or TPV), the recycled polyolefin portion and optionally the virgin polyolefin portion comprised in the at least one polyolefin each independently of one another comprise a homopolymer or copolymer of propylene, preferably a homopolymer or copolymer of recycled propylene derived from a recycled polyolefin material or a regenerated polyolefin material of the PIR or PCR type. For example, the at least one polyolefin comprises:

[0049] - recycled propylene homo- or copolymer (PP) having a mass fraction in said at least one polyolefin of 50% to 100%, which may be equal to or greater than 75% and less than 100%, both inclusive; and

[0050] - a virgin propylene homo- or copolymer (PP) having a mass fraction in said at least one polyolefin ranging from 0% to 50%, which may be greater than 0% and less than or equal to 25%, both inclusive.

[0051] According to an even more preferred example of a TPV type composition according to the invention, at least one EPDM is used as elastomer and at least one propylene homopolymer (PP) is used as polyolefin, in which case:

[0052] - the mass fraction of the at least one EPDM in the composition is 15% to 25%, for example 17% to 22%, inclusive; and / or

[0053] - a mass fraction of recycled PP of 28% to 50%, such as 30% to 45%, inclusive; and / or

[0054] - a mass fraction of original PP of 15% to 35%, for example 17% to 32%, inclusive; and / or

[0055] The total mass fraction of recycled PP and virgin PP is 40% to 70%, such as 50% to 68%, inclusive.

[0056] In this specification, "reinforcing filler" generally refers to one or more individual fillers used in reinforcing grades of elastomers, which preferably consist entirely or partly of reinforcing carbon black and are uniformly dispersed in the composition, providing that the reinforcing filler may further comprise an organic filler other than carbon black (e.g. graphite) and optionally further comprise an inorganic filler, such as silica or another non-black filler.

[0057] Advantageously, the reinforcing filler may comprise carbon black, optionally at least partly recycled and for example of the ASTM N500 or N600 series, present in a TPE type composition (for example TPS, TPO or TPV) in a mass fraction ranging from 1% to 15%, preferably from 4% to 10% inclusive.

[0058] It will be noted that this relatively small amount of carbon black in the composition makes it particularly possible to impart to a single-layer hose made from this composition a compromise between a relatively high resistivity and sufficient reinforcement and thus minimize the electrochemical degradation of the hose in contact with the fluid it conveys, when this fluid is a cooling fluid of the glycol-water type, without compromising the resistance of the hose to its external environment.

[0059] According to another general feature of the TPE-type composition (e.g., TPS, TPO, or TPV) of the present invention with respect to any of the aforementioned features, the composition may comprise:

[0060] - the mass fraction of the plasticizing system is 3% to 25%, preferably 4% to 15%, and for example 5% to 12% (limit values ​​included),

[0061] - Preferably, the mass fraction of carbon black in the composition is 1% to 15%, such as 4% to 10% (inclusive).

[0062] As plasticizing system according to the invention, at least one plasticizing oil and / or at least one plasticizing resin can be used, providing that the plasticizing system preferably comprises at least one plasticizing oil selected from mineral oils, bio-based oils derived from biomass (including modified or unmodified vegetable oils) and mixtures thereof.

[0063] Even more preferably, as plasticizing system, at least one plasticizing oil selected from paraffinic, naphthenic and aromatic mineral oils is used, for example at least partly naphthenic mineral oils (which may comprise simultaneously paraffinic, naphthenic and aromatic fractions).

[0064] It will be noted that the use of the plasticizing system in reduced mass fractions according to the invention compared to the much higher mass fractions conventionally used in hoses still enables the invention composition having the above-mentioned properties to be implemented by mixing followed by extrusion or simply by reactive extrusion.

[0065] According to another general characteristic of the invention, when the composition is of the TPV type, it comprises a crosslinking system that is free of phenolic resins and zinc oxide (ZnO) and preferably comprises an organic peroxide as a crosslinking agent and a crosslinking auxiliary agent chosen from triallyl cyanurate (TAC), triallyl isocyanurate (TAIC), and an acrylate-based auxiliary agent such as ethylene glycol dimethacrylate (EGDMA).

[0066] Alternatively, the TPV-type composition according to the invention may comprise a sulfur crosslinking system, optionally also comprising a peroxide crosslinking agent.

[0067] The crosslinking system of the TPV composition according to the invention allows the composition to be chemically crosslinked, preferably by reactive extrusion, and further, since the crosslinking system is completely free of ZnO, it does not inhibit the rust prevention systems used in the cooling circuit (with which ZnO, used as a crosslinking activator in prior art rubber compositions, is known to interact adversely).

[0068] Generally, with reference to any of the preceding characteristics, the antioxidant system of the TPV-type composition according to the invention may advantageously comprise:

[0069] - a first antioxidant, preferably a heterocyclic aromatic antioxidant, for example based on polymeric 2,2,4-trimethyl-1,2-dihydroquinoline, and

[0070] - a second antioxidant, a thioether-based antioxidant such as distearyl disulfide,

[0071] And preferably, the antioxidant system further comprises a third antioxidant based on aromatic amines.

[0072] It should be noted that this mixed and preferably ternary antioxidant system advantageously allows the TPV compositions according to the invention to be endowed with improved mechanical properties after heat aging in air and in glycol water, compared to the mechanical properties of a reference TPV composition of a similar formulation in which the at least one polyolefin is completely virgin (i.e., not at least partially recycled).

[0073] According to other characteristics of the TPV-type compositions of the present invention, these compositions may have:

[0074] a continuous phase comprising said at least one polyolefin, and a discontinuous phase comprising nodules of said at least one elastomer (for example at least one EPDM) dispersed in said at least one polyolefin, and

[0075] - stress at break and elongation at break, measured in a uniaxial tensile test according to standard ISO 37:2017 after 3000 hours of aging at 120° C. in contact with air and glycol water, respectively, which are higher than those of the reference TPV composition, in which the at least one polyolefin consists, for example, of a virgin propylene homopolymer.

[0076] With reference to any of the foregoing features, according to another general aspect of the present invention, the TPE-type composition (e.g., TPS, TPO or TPV) according to the present invention can be prepared by mixing in an internal mixer followed by twin-screw extrusion, or alternatively by a single reactive twin-screw extrusion step.

[0077] With reference to any of the preceding features, according to another general aspect of the invention, the elastomer or elastomer-textile or metal composite article according to the invention comprises or consists of an extrudate formed from a TPE-type composition according to the invention (e.g. TPS, TPO or TPV), the article being particularly chosen from single-layer hoses, multi-layer hoses optionally reinforced with a textile core, gaskets for automobiles or for buildings, anti-vibration devices and elements for supporting, choking or protecting battery packs or data processing centers.

[0078] Advantageously and in a non-limiting manner, the article may be an extruded single- or multi-layer hose for the cooling circuit of a battery or electric motor of an electric or hybrid vehicle, preferably made of said TPE type composition (for example TPS, TPO or TPV) and usable in temperatures up to 3.0.10 5 Single-layer hose for conveying cooling fluid from batteries at a pressure of Pa and a temperature of up to 120°C.

[0079] As explained above, the mechanical properties of the TPE composition, and therefore the single-layer hose made therefrom, are sufficient to enable the transport of cooling fluids with good dynamic performance under these temperature and pressure conditions. Consequently, compared to prior art reinforced hoses, the single-layer hose according to the first embodiment of the present invention can have reduced inner and outer diameters, making it oversized for low-pressure and low-temperature circuits. Consequently, the manufacturing cost of the hose according to the first embodiment of the present invention is significantly reduced compared to known reinforced hoses used in automotive cooling systems.

[0080] The hose according to the second embodiment of the invention is of the multilayer type, comprising a radially inner layer, a radially outer layer and an optional reinforcing core (e.g. textile or metal), wherein the inner and / or outer layer consists of a TPE-type composition according to the invention (e.g. TPS, TPO or TPV), as defined above with reference to any of the above features.

[0081] As reinforcing core, at least one textile or non-textile reinforcing core (eg a core made of knitted, braided or covered yarns such as PET, aramid or rayon) covering the inner layer may be used.

[0082] The hose according to the second embodiment of the present invention can be used in a range of temperatures exceeding 3.10 5 The invention can transport liquids, gases or supercritical fluids at pressures of up to 1 Pa and / or at temperatures that can exceed 120°C.

[0083] It should be noted that the hose according to the second embodiment of the invention may also comprise a barrier layer of plastic material based on at least one thermoplastic polymer. This barrier layer may form the radially innermost layer of the hose, or an 'insulating layer' between the inner tube and the reinforcing layer or between the inner tube and the intermediate layer.

[0084] A fluid circuit according to the invention, in particular for cooling a battery or an electric motor for a hybrid or electric vehicle, comprises a plurality of single-layer and / or multi-layer hoses mounted to a connector (e.g. a thermoplastic connector) and may be characterized in that at least one (and preferably each) hose is as defined above.

[0085] In this specification, the term "based on" means that the composition or ingredient in question comprises essentially the component in question by weight, ie a mass fraction of greater than 50%, preferably greater than 75% and up to 100%.

[0086] The present invention also relates to a thermoplastic elastomer composition, in particular a single-layer (1) or multi-layer (10, 20, 30, 40) hose that can be used for the cooling circuit of a battery or an electric motor of an electric or hybrid vehicle, comprising:

[0087] (i) at least one elastomer,

[0088] (ii) at least one polyolefin comprising

[0089] - a recycled polyolefin fraction derived from "PIR" or "PCR" type recycling (i.e. recycled polyolefin material of the post-industrial (PIR) or post-consumer (PCR) type) or from grinding and subsequent regeneration in an extruder, and

[0090] - optionally a virgin polyolefin fraction,

[0091] (iii) a reinforcing filler comprising carbon black,

[0092] (iv) a plasticizing system comprising at least one plasticizing oil and / or at least one plasticizing resin, and

[0093] (v) an antioxidant system comprising several antioxidants (at least two antioxidants), one of which is a thioether-based antioxidant,

[0094] The composition comprises, by mass fraction:

[0095] - greater than 35% of said at least one polyolefin, and

[0096] - Less than 30% of said plasticizing system. BRIEF DESCRIPTION OF THE DRAWINGS

[0097] Other features, advantages and details of the invention will become apparent from a reading of the following description of several exemplary embodiments of the invention given by way of illustration in conjunction with the accompanying drawings, in which:

[0098] Figure 1

[0099] [ Figure 1 ] is a schematic side perspective view of a single-layer hose according to the present invention.

[0100] Figure 2

[0101] [ Figure 2 ] is a schematic side perspective view of a partial cross-section of a multi-layer hose according to one embodiment of the present invention.

[0102] Figure 3

[0103] [ Figure 3 ] is a schematic side perspective view of a partial cross-section of a multi-layer hose according to another embodiment of the present invention.

[0104] Figure 4

[0105] [ Figure 4 ] is a schematic side perspective view of a partial cross-section of a multi-layer hose according to another embodiment of the present invention.

[0106] Figure 5

[0107] [ Figure 5 ] is a schematic side perspective view of a partial cross-section of a multi-layer hose according to another embodiment of the present invention.

[0108] Figure 6

[0109] [ Figure 6 ] is an atomic force microscope (AFM) photograph showing the morphology of a reference composition not according to the present invention.

[0110] Figure 7

[0111] [ Figure 7 ] is an AFM photograph showing the morphology of the first composition according to the present invention.

[0112] Figure 8

[0113] [ Figure 8 ] is an AFM photograph showing the morphology of the second composition according to the present invention.

[0114] Figure 9

[0115] [ Figure 9 ] is a stress-strain diagram of the reference composition and the second composition according to the present invention before aging.

[0116] Figure 10

[0117] [ Figure 10 ] is a stress-strain diagram of the reference composition and the second composition according to the present invention after thermal aging in ethylene glycol water.

[0118] Figure 11

[0119] [ Figure 11 ] is a stress-strain diagram of the reference composition and the second composition according to the present invention after heat aging in air.

[0120] Figure 12

[0121] [ Figure 12 ] are stress-strain diagrams of the reference composition and the composition according to the invention before aging. Specific implementation plan

[0122] Figure 1 The single-layer hose 1 can be no more than 3.10 5 The hose 1 is used to transport fluids such as cooling fluids at a pressure of 100 Pa and a temperature not exceeding 120° C. and can be assembled to two connectors, such as thermoplastic connectors. The hose 1 is composed of a TPE composition according to the invention (such as TPS, TPO or TPV) as defined above.

[0123] Figure 2 The multi-layer hose 10 can be equal to or greater than 3.10 5 Pa, such as those mentioned above, and comprising a radially inner tube 11, a reinforcing layer 12 and a radially outer coating 13, provided that at least one of the tube 11 and the coating 13 consists of a TPE composition according to the invention as defined above (for example TPS, TPO or TPV).

[0124] The reinforcement layer 12 may comprise, in a non-limiting manner, a knitted, woven or covered fabric based on multifilament yarns made of one or more textile materials, such as polyamide (e.g. aramid), polyester (e.g. PET) or rayon (the term 'yarn' generally refers to textile yarns made of a plurality of elementary filaments of small diameter twisted together and folded yarns obtained by twisting several textile yarns).

[0125] Figure 3 The multi-layer hose 20 and Figure 2 The difference is that the inner tube 21 is covered with an intermediate layer 22, which is itself covered with a reinforcing layer 23, which is covered with a coating 24, providing that at least one of the tube 21 and the coating 24 consists of a TPE composition according to the invention.

[0126] Figure 4 Multilayer hose 30 with Figure 3 The multilayer hose of the present invention differs in that an inner tube 31 is covered with an inner reinforcement layer 32, which is itself covered with an intermediate layer 33, which is covered with an outer reinforcement layer 34 and then with a coating layer 35, providing that at least one of the tube 31, the intermediate layer 33 and the coating layer 35 consists of a TPE composition according to the invention.

[0127] Figure 5 Multilayer hose 40 with Figure 3 The multilayer hose of the present invention differs in that an inner tube 41 is covered with a barrier layer 42 of a plastic material forming an insulating layer, which is then covered with an intermediate layer 43, which is covered with a reinforcing layer 44, which is itself covered with a coating 45, providing that at least one of the tube 41, the intermediate layer 43 and the coating 45 consists of a TPE composition according to the invention.

[0128] It should be noted that the multilayer hose according to the invention may comprise as many layers as possible, with respect to the number of layers and their respective functions. Figure 2-5 The arrangements of the layers are different from those shown in .

[0129] Preparation of the reference composition C1, the first composition I1 according to the invention and the second composition I2 according to the invention:

[0130] Three thermoplastic vulcanizate (TPV) compositions have been prepared by implementing the following preparation method, forming respectively a reference composition C1 and a first and a second composition I1 and I2 according to the invention, for example capable of constituting a single-layer hose for a cooling circuit.

[0131] First, a mixing step was carried out in an internal mixer, incorporating the ingredients listed below into a mixing cycle (elastomer, polyolefin, processing agent and plasticizing system first, then crosslinking system and finally antioxidant system at the end of the cycle) in which the temperature was increased to a steady state of 200°C due to shear for 8 minutes.

[0132] Next, a step of extruding the recovered mixture was performed at 190° C. in a twin-screw extruder.

[0133] Each of the three TPV compositions C1, I1, and I2 obtained in this manner was then formed into dumbbell-shaped test pieces having a dimension H2 for measuring the mechanical properties (stress / strain curves and resulting fracture properties) in the crosslinked state. These properties were thus measured in a uniaxial tensile test at 23° C. according to ISO 37:2017, both in the initial state and after two types of heat aging.

[0134] Table 1 below details the formulation of composition C1 thus prepared (in parts by weight of each ingredient in the composition).

[0135] [Table 1]

[0136]

[0137] [Chemical Formula 1]

[0138]

[0139] [Chemical Formula 2]

[0140]

[0141] Table 2 below details the formulations of the compositions I1 and I2 thus prepared (in parts by weight of each ingredient in the composition).

[0142] [Table 2]

[0143]

[0144] Thus, composition I1 contains 195 parts by weight of a post-industrial recycled (i.e. "PIR" type) polyolefin material designated 'PRC50 UFO Black' comprising:

[0145] - 50 wt.% recycled polypropylene rPP, which mainly comprises propylene homopolymer or copolymer, i.e. 97.5 parts by weight of rPP, and

[0146] 50% by weight of other ingredients, which may comprise mainly virgin polypropylene vPP (propylene homopolymer or copolymer, identical to or different from rPP), and at least one additive present in trace amounts (such as an antioxidant), i.e. 97.5 parts by weight of these other ingredients.

[0147] Thus, the mass fractions of rPP and vPP in composition I1 are each about 31%, while the mass fractions of EPDM, carbon black, and plasticizer in composition I1 are each 19%, 7%, and 8%, respectively.

[0148] Thus, composition I2 contains 170 parts by weight of a post-consumer recycled (i.e. 'PCR' type) polyolefin material designated 'rPP1002' comprising:

[0149] - 70 wt.% of recycled polypropylene rPP, which mainly comprises propylene homopolymer or copolymer, i.e. 119 parts by weight of rPP, and

[0150] 30% by weight of other ingredients, which may comprise mainly virgin polypropylene vPP (propylene homopolymer or copolymer, identical to or different from rPP), and at least one additive present in trace amounts (such as an antioxidant), i.e. 51 parts by weight of these other ingredients.

[0151] Thus, the mass fractions of rPP and vPP in composition I2 are approximately 41% and 18%, respectively, while the mass fractions of EPDM, carbon black, and plasticizer in composition I2 are 21%, 8%, and 9%, respectively.

[0152] like Figure 6-8 As shown in the photographs in Figure 1, atomic force microscopy (AFM) morphological analysis shows that for each of the three compositions C1, I1, and I2, the polyolefin thermoplastic phase (PP) is continuous and the elastomeric phase (EPDM) has a structure of elastic agglomerates dispersed in a rigid matrix of the continuous polyolefin phase. These photographs further show that the average size of the elastomer agglomerates is reduced in compositions I1 and I2 according to the invention compared to composition C1.

[0153] It has been demonstrated that the rheological and extrudability properties of compositions I1 and I2 according to the invention are similar to those of reference composition C1.

[0154] As indicated above, uniaxial tensile tests were carried out at 23°C according to standard ISO 37:2017 on H2 test pieces made from compositions C1 and I2 in the initial state (i.e. before any exposure of the composition to the fluid and any operating conditions characterizing its operation), with the results being Figure 9 This can be seen in the stress / strain curve.

[0155] like Figure 9 As shown, it has been confirmed that the mechanical tensile properties, in particular the breaking properties, of composition I2 are similar to those of composition C1 in the initial state (see quasi-superposition of the curves of I2 and C1 from low to high strain).

[0156] These uniaxial tensile tests were then again carried out according to standard ISO 37:2017 on H2 test pieces made of compositions C1 and I2, but after two separate heat aging cycles, respectively in contact with a cooling fluid made of ethylene glycol water and in contact with air.

[0157] like Figure 10 As shown in , after 3000 hours of heat aging by immersion in a 50% / 50% water / ethylene glycol solution at 120° C., it has been demonstrated that the tensile properties (measured at 23° C.) and in particular the breaking properties of composition I2 are improved relative to those of composition C1 (see the curve for I2, which reflects the lower stress for a given strain, starting from 80% relative strain, relative to the stress applied to the same strain of composition C1, and the maximum stress of I2 is higher than that of C1 at the highest strain).

[0158] like Figure 11 As shown in , after heat aging for 3000 hours at 120°C in air, it has been demonstrated that the tensile properties (measured at 23°C) and in particular the breaking properties of composition I2 are also improved relative to those of composition C1 (see the curve for I2, which reflects a lower stress for a given strain, starting from 30% relative strain, relative to the stress applied to the same strain of composition C1, and the maximum stress of I2 is higher than that of C1 at the highest strain).

[0159] In conclusion, the compositions I1 and I2 according to the invention, which are characterized in particular in that they contain a mass fraction of durable polyolefins (for example recycled polypropylene) greater than 30%, or even greater than 40% (composition I2), and therefore have a reduced carbon footprint relative to the reference composition (a 29% reduction in the carbon footprint for composition I1 and a 30% reduction in the carbon footprint for composition I2), have similar and even improved heat aging resistance relative to composition C1 (see composition I2), both in contact with glycol fluids and with air, which demonstrates the suitability and even superiority of the compositions of the invention for forming the inner and / or outer layer of single-layer or multilayer tubes, in particular for the cooling circuit of batteries or electric motors of automobiles.

[0160] It should be noted that such heat aging resistance, which is similar to or even improved upon that of the compositions of the present invention, can be achieved in particular by the above-mentioned mixed antioxidant system, which comprises, in addition to the other ingredients of the compositions of the present invention, a first antioxidant (preferably a heterocyclic aromatic antioxidant) and a second antioxidant (a thioether-based antioxidant).

[0161] It will also be noted that since the compositions of the invention do not contain zinc oxide, they advantageously do not interact with the anti-rust system used in the cooling circuit, said anti-rust system therefore not being inhibited and fully ensuring its protective function.

[0162] Preparation of compositions I3 to I5 according to the invention:

[0163] Compositions I3 to I5 according to the invention were prepared according to the above-described protocol. The amount of polypropylene (PP) having recycled (rPP) and virgin (vPP) fractions varied in the different compositions. Table 3 below details the formulations of the compositions I3 to I5 thus prepared (in parts by weight of each ingredient in the composition).

[0164] [Table 3]

[0165]

[0166] The mass fractions of rPP and vPP are as follows:

[0167] - in composition I3, about 28% rPP and 12% vPP,

[0168] - in composition I4, about 35% rPP and 15% vPP,

[0169] - In composition I5, about 50% rPP and 20% vPP.

[0170] Uniaxial tensile tests were carried out at 23°C according to standard ISO 37:2017 on H2 test pieces made from compositions I3, I4 and I5 in the initial state (ie before any exposure of the composition to the fluid and any operating conditions characterizing its operation) and the results are given in Figure 12 This can be seen in the stress / strain curve.

[0171] like Figure 12 As shown, the results show that the compositions of the present invention have satisfactory breaking and elongation properties.

Claims

1. A thermoplastic elastomer composition, in particular a single-layer (1) or multi-layer (10, 20, 30, 40) hose that can be used for a cooling circuit of a battery or an electric motor of an electric or hybrid vehicle, comprising: (i) at least one elastomer, (ii) at least one polyolefin comprising a recycled polyolefin fraction and optionally a virgin polyolefin fraction, (iii) reinforcing fillers, (iv) a plasticizing system, and (v) antioxidant system, The composition comprises, by mass fraction: - greater than 35% of said at least one polyolefin, and - Less than 30% of said plasticizing system.

2. The composition according to claim 1, wherein the composition comprises, by mass fraction, more than 25%, preferably 28% to 50%, for example 30% to 45% (limited values ​​included) of the recycled polyolefin fraction.

3. The composition according to claim 1 or 2, wherein the composition comprises, by mass fraction, more than 10%, preferably 15% to 35% (inclusive) of the virgin polyolefin portion.

4. The composition according to claim 3, wherein the composition comprises, in total mass fraction, 40% to 70%, preferably 50% to 68%, for example 55% to 65% (inclusive) of the recycled polyolefin portion and the virgin polyolefin portion.

5. Composition according to any one of the preceding claims, wherein the composition comprises, by weight, 3% to 25%, preferably 4% to 15%, and for example 5% to 12% (limits included) of the plasticizing system.

6. The composition according to any one of the preceding claims, wherein the at least one polyolefin comprises: - a homopolymer of at least one α-olefin, for example propylene, or - interpolymers of ethylene and at least one α-olefin, such as propylene, The recycled polyolefin fraction preferably comprises recycled propylene homopolymer or copolymer derived from post-industrial recycled (PIR) or post-consumer recycled (PCR) polyolefin material, and for example wherein the recycled polyolefin portion and the virgin polyolefin portion independently of each other respectively comprise: - recycled propylene homopolymer or copolymer (PP) having a mass fraction in the at least one polyolefin of 50% to 100%, inclusive; and - a virgin propylene homo- or copolymer (PP) having a mass fraction in the at least one polyolefin of 0% to 50%, inclusive.

7. The composition of claim 6, wherein the composition is a thermoplastic vulcanizate (TPV) and the at least one elastomer is selected from: -EPDM, - homopolymers or copolymers of butadiene and / or isoprene and optionally further vinylaromatic comonomers, acrylonitrile or branched α-olefins, - copolymers of ethylene and at least one linear or branched α-olefin having 3 to 20 carbon atoms, and - acrylic rubbers of the polyacrylate (ACM) or polyacrylate polyethylene (AEM) type, Preferably, wherein the at least one elastomer is selected from ethylene-propylene-diene terpolymer (EPDM), butyl rubber (IIR) and octene-ethylene copolymer (POE), and Preferably, the mass fraction of the at least one elastomer in the composition is between 10% and 40%, inclusive.

8. The composition according to claim 7, wherein the composition comprises a crosslinking system which is free of phenolic resins and zinc oxide and preferably comprises an organic peroxide as a crosslinking agent and a crosslinking auxiliary selected from triallyl cyanurate (TAC), triallyl isocyanurate (TAIC), and an acrylate-based auxiliary such as ethylene glycol dimethacrylate (EGDMA).

9. The composition according to claim 7 or 8, wherein the at least one elastomer is an ethylene-propylene-diene terpolymer (EPDM), the ethylene of which is optionally bio-based, and Preferably, the mass fraction of the at least one elastomer in the composition is between 15% and 25%, inclusive.

10. Composition according to any of the preceding claims, wherein the reinforcing filler comprises carbon black, optionally at least partly recycled and for example of the ASTM N500 or N600 series, present in the composition in a mass fraction comprised between 1% and 15%, preferably between 4% and 10% (limits inclusive).

11. The composition of any one of the preceding claims, wherein the antioxidant system comprises: - a first antioxidant, preferably a heterocyclic aromatic antioxidant, for example based on polymeric 2,2,4-trimethyl-1,2-dihydroquinoline, and - a second antioxidant, a thioether-based antioxidant such as distearyl disulfide, And preferably, the antioxidant system further comprises a third antioxidant based on aromatic amines.

12. The composition of claims 9, 10, and 11, wherein the composition forming the thermoplastic vulcanizate (TPV) comprises a continuous phase comprising the at least one polyolefin and a discontinuous phase comprising agglomerates of the at least one elastomer dispersed in the at least one polyolefin, and wherein the composition has a stress at break and an elongation at break measured in a uniaxial tensile test according to standard ISO 37:2017 after aging for 3000 hours in contact with air and ethylene glycol water, respectively, at 120° C., which are higher than the stress at break and the elongation at break of a reference thermoplastic vulcanizate composition, wherein the at least one polyolefin without the recycled polyolefin portion consists of virgin propylene homopolymer (PP).

13. according to the composition described in any one of the preceding claims, wherein said plasticizing system comprises at least one oil, said oil is selected from mineral oil, biomass derived biological base oil such as modified or unmodified vegetable oil, and their mixture, and For example, wherein the at least one oil is selected from paraffinic mineral oil, naphthenic mineral oil and aromatic mineral oil.

14. An elastomer or elastomer-textile or metal composite article, in particular selected from single-layer hoses (1), multi-layer hoses (10, 20, 30, 40) optionally reinforced with a textile core (12, 23, 32, 34, 44), for use in gaskets for automobiles or for buildings, for supporting, cushioning or protecting battery packs or shock-absorbing devices and components of data processing centers, wherein the article comprises or consists of an extrudate formed from the composition according to any one of the preceding claims.

15. The article according to claim 14, wherein the article is an extruded single-layer (1) or multi-layer (10, 20, 30, 40) hose for a cooling circuit of a battery or an electric motor of an electric or hybrid vehicle, and preferably wherein The article is a single-layer hose (1) consisting of the composition and can be used in applications up to 3.0.10 5 The cooling fluid from the battery is delivered at a pressure of 100 Pa and a temperature of up to 120°C.

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