Single or multi-layer tubular structures based on recycled polyamide

Abstract

The present invention provides a composition comprising: (a) 30% to 99.8% (by weight), in particular 50% to 99.8% (by weight), of recycled material from used single-wall and / or multi-wall tubes and / or tanks that originally transported or contained motor vehicle fluids, in particular air, oil, water, urea solutions, glycol-based coolants, or fuels, such as gasoline, in particular alcohol-blended gasoline, biogasoline or diesel, in particular biodiesel, or hydrogen, said tubes and / or said tanks consisting of a composition that mainly comprises at least one polyamide, recycled material, in which the used single-wall and / or multi-wall tubes and / or the used tanks have been crushed into granules and the fluid residues present in the tubes and / or tanks have been fully or partially extracted before or after crushing of the tubes and / or tanks; (b) up to 70%, in particular up to 50%, semicrystalline aliphatic polyamides; (c) up to 0.2% of additives, The polyamide of the used tube and / or the used tank has a greater molar ratio of functional groups resulting from an oxidation reaction selected from primary amide functional groups, nitriles, terminal methyl groups, alkenes, formamides, imides, carboxylic acids and alcohols, and mixtures thereof, than the same polyamide constituting a virgin tube and / or tank that has not yet transported or contained a motor vehicle fluid.

Description

[Technical field]

[0001] The present invention relates to a composition obtained from used polyamide pipes from motor vehicles, to a single or multi-layer tubular structure comprising at least one layer of said composition, and to a process for its manufacture. [Background technology]

[0002] Every year, millions of motor vehicles reach end of life worldwide. End of life motor vehicles (ELVs) contain numerous toxic and pollutant products (liquid or solid), such as used oil, batteries, air conditioning fluids, and explosive elements from airbags. If handled under improper conditions, this waste can cause ground and water contamination, as well as accidents. Therefore, ELVs are considered hazardous waste.

[0003] Large amounts of vehicle components can be recovered and recycled in the form of used spare parts or raw materials. Parts intended for reuse (headlights, turn signals, engines, radiators, starters, hoods, wings, doors, etc.) are dismantled and stored for resale.

[0004] The carcass and non-recyclable parts (ferrous and non-ferrous metals, plastics, glass, rubber, etc.) are separated and crushed for reuse or landfill.

[0005] The European Directive 2000 / 53 / EC on end-of-life vehicles sets a reuse and recycling level of 95% (by weight) per vehicle from 2015.

[0006] This means that only 5% should remain as final waste, i.e. waste that is not suitable for treatment under current technical and economic conditions and which is incinerated or disposed of in special landfills.

[0007] The 95% that is reused and recycled goes through the following process: Energy recovery: the use of waste (oil, tyres, plastics etc.) as a means of generating energy, by direct incineration with or without other waste; Material Reuse: Reuse or Recycle: A new use for a part that retains the same use and is not modified; or Recycling: Operations aimed at introducing materials from waste into the production cycle, completely or partially replacing them with virgin materials.

[0008] A motor vehicle comprises a large number of pipes, inter alia, for transporting fluids such as air, oil (e.g. for cooling an automatic transmission (transmission oil cooler (TOC)), water, urea solutions, glycol-based coolants, fuels, e.g. gasoline, in particular biogasoline or diesel, in particular biodiesel, or hydrogen.

[0009] It also includes a tank in which said fluid is stored within the vehicle.

[0010] These pipes may in particular be single- and / or multi-layer tubular structures based on polyamide, likewise the tanks may in particular be single- and / or multi-layer structures based on polyamide.

[0011] When a motor vehicle is at the end of its life, the various tubes present therein are typically severely degraded or too degraded to be reused in tube form without risk or leading to excessively degraded operating characteristics.

[0012] Specifically, tubes, especially those under the engine hood, are subject to a severe thermo-oxidative environment due to the heat generated by the engine, which can typically be up to 150° C., and the presence of air, and therefore oxygen. Every 10° C. increase in temperature typically results in a halving of the tube life, as well as a degradation of certain additives in said tubes, such as stabilizers.

[0013] So far, pipes or fuel tanks of motor vehicles at the end of their life are not reused but are often incinerated, which contributes to global warming, the reduction of which is one of the major challenges of the 21st century.

[0014] Furthermore, many motor vehicle manufacturers have set themselves more or less long-term goals of recycling 100% of the vehicles they produce in order to achieve a zero environmental impact.

[0015] As a result, supplying these manufacturers with recycled pipes is of paramount importance, reducing the amount that must be disposed of or incinerated.

[0016] Reuse of tubes removed from end-of-life vehicles without modification is not anticipated for the following reasons: Analysis of end-of-life tubes shows that they have become stiffer compared to new tubes: end-of-life tubes have a higher threshold stress (loss of additives and crystallization caused by the working environment). This reinforcement is problematic because there is a risk that the tubes will be damaged during disassembly and assembly in new vehicles (the tubes are especially stressed during feathering).

[0017] Additionally, end of life tubes are thermoformed during installation into a new vehicle to fit the exact vehicle model, a model that will likely no longer be manufactured 10-15 years after the sale of said vehicle.

[0018] The tank has a specific shape suited to each vehicle model, which changes periodically.

[0019] Traditionally, when used tubes are recycled, they are first crushed, then recompounded and possibly reformulated before being extruded to produce new tubes.

[0020] It is necessary to find ways to reuse or recycle these tubes in order to limit the environmental impact of the automotive industry and to limit the recycling costs of used pipes in order to provide automotive manufacturers with pipes at a price that is compatible with the range of vehicles sold.

[0021] Accordingly, the present invention provides a composition comprising: (a) 30% to 99.8% (by weight), in particular 50% to 99.8% (by weight), of recycled material from used single-wall and / or multi-wall tubes and / or tanks that originally transported or contained motor vehicle fluids, in particular air, oil, water, urea solutions, glycol-based coolants, or fuels, such as gasoline, in particular alcohol-blended gasoline, biogasoline or diesel, in particular biodiesel, or hydrogen, said tubes and / or said tanks consisting of a composition that mainly comprises at least one polyamide, recycled material, in which the used single-wall and / or multi-wall tubes and / or the used tanks have been crushed into granules and the fluid residues present in the tubes and / or tanks have been fully or partially extracted before or after crushing of the tubes and / or tanks; (b) up to 70%, in particular up to 50%, semicrystalline aliphatic polyamides; (c) up to 45% (by weight) of at least one impact modifier, in particular from 1% to 45% (by weight) of at least one impact modifier, in particular from 2% to 45% (by weight) of at least one impact modifier; (d) up to 20% (by weight) of at least one plasticizer; (e) up to 0.2% of additives, The polyamide of the used tube and / or the used tank has a molar ratio of functional groups resulting from an oxidation reaction selected from primary amide functional groups, nitriles, terminal methyl groups, alkenes, formamides, imides, carboxylic acids and alcohols, and mixtures thereof, to amide functional groups that is greater than the same polyamide constituting a virgin tube and / or tank that has not yet transported or contained a motor vehicle fluid.

[0022] Advantageously, said used single layer and / or multi-layer tubes and / or said used tanks are only crushed into granules, excluding reformulation with or without subsequent reformulation after crushing.

[0023] Said used mono- and / or multi-layer tubes and / or used tanks therefore exclude virgin mono- and / or multi-layer tubes and / or tanks, i.e. tubes or tanks that have never transported or contained a motor vehicle fluid, but whose intended purpose is said transport of a motor vehicle fluid, thus effectively excluding scrap from the manufacture of mono- and / or multi-layer tubes and / or tanks for transporting or storing a motor vehicle fluid.

[0024] In one embodiment, the composition of the tube and / or tank excludes polyphenylene sulfide (PPS).

[0025] The term "motor vehicle" means any vehicle having a thermal, electric or hybrid engine with wheels or tracks, excluding flying vehicles.

[0026] The motor vehicle may be a two-wheeled, three-wheeled, four-wheeled, or tracked vehicle.

[0027] For example, the vehicle may be selected from electric bicycles, mopeds, motorcycles, sidecars, cars, vans, tractors, trucks, buses, coaches, snowmobiles, auto chenilles, bulldozers, snow groomers, and tanks.

[0028] In particular, the vehicle is selected from cars, vans, trucks, buses and coaches.

[0029] In particular, it is selected from internal combustion engine cars, vans, trucks, buses and coaches.

[0030] When tubes or tanks for transporting or storing fluids are used in motor vehicles, new species arising from oxidation mechanisms, particularly amide functional groups and / or methylene alpha to said amide functional groups, such as primary amide functional groups, nitriles, terminal methyl groups, alkenes, formamides, imides, carboxylic acids and alcohols, are found in the polyamides from which said tubes or tanks are constructed. Said functional groups can be detected by infrared spectroscopy.

[0031] A terminal methyl group is, for example, the CH3 group of a CH3(CH2)n group.

[0032] Alkenes correspond to CH2=CH-.

[0033] Therefore, 1700~1740cm -1 The absorption band corresponds to imide, and is 1680-1720 cm -1 The absorption band corresponds to the carbonyl of carboxylic acid, and is located at 3580-3670 cm -1 The absorption band corresponds to the alcohol functional group of the carboxylic acid.

[0034] 3580~3670cm -1 The absorption band at 100 nm corresponds to the free alcohol functional group.

[0035] On the one hand, the amide functional group has a peak at 3100-3500 cm corresponding to the NH group of the amide. -1 and 1560~1640cm -1 and on the other hand, a pair of absorption bands at 1650–1700 cm corresponding to the carbonyl group of the amide. -1 It is characterized by an absorption band of

[0036] Infrared light allows the detection of the presence or absence of said new species resulting from the oxidation mechanism.

[0037] Quantitation of the new species resulting from the oxidation mechanism is performed by proton NMR in dichloromethane-d2 with the addition of HFIP (hexafluoroisopropanol) to dissolve the polyamide.

[0038] For example, 20 mg of polymer can be dissolved in 0.7 mL of solvent with a 1 / 3 HFIP / CD2Cl2 ratio.

[0039] Some of the functional groups mentioned below are, for example, 13 C NMR. Thus, the line at 36 ppm corresponds to the CH2 alpha to the primary amide, and the line at 34 ppm corresponds to the CH2 alpha to the carboxylic acid. These species can be quantified by integrating the areas under the lines and comparing them to the area under the 37.1 ppm line, which corresponds to the secondary amide.

[0040] Similarly, lines corresponding to the carbonyl groups of the primary amide, carboxylic acid and secondary amide functionalities are observed at 181.2 ppm, 179.6 ppm and 177.4 ppm, respectively.

[0041] The line at 16.7 ppm corresponds to the CH2 alpha to the nitrile group.

[0042] The formamide groups give chemical shifts at 163.0 ppm and 166.3 ppm.

[0043] The other functional groups were analyzed by proton NMR ( 1 H NMR). Lines for formamide CHO groups appear at 7.92 ppm and 8.01 ppm. A line corresponding to the CH2 group alpha to the primary amide can be observed at 2.30 ppm. The line at 0.9 ppm corresponds to a CH3 group of the type CH3-(CH2)n. The line at 2.40 ppm corresponds to the CH2 alpha to the nitrile functionality. Similar to what was described for carbon NMR, the ratio of new functionality to secondary amide can be determined by integrating the areas under the lines and comparing them to the area under the line corresponding to the CH2 alpha to the secondary amide (2.20 ppm).

[0044] The inventors have therefore surprisingly found that the use of at least 30% (by weight), in particular at least 50% (by weight), of recycled material based on partially oxidized polyamide and originating from used, only ground mono- and / or multi-layer tubes and / or tanks, in which the fluid residues present in said tubes and / or tanks have been fully or partially extracted with semi-crystalline aliphatic polyamide and optionally additives before or after grinding of said tubes and / or tanks, allows the constitution of a composition which can then be converted into a tube or tank whose mechanical properties are comparable to those of tubes or tanks obtained from non-recycled and virgin material, i.e. new tubes or tanks.

[0045] The expression "said used single layer and / or multi-layer tube and / or said used tank" means that said single layer and / or multi-layer tube and / or said tank were originally installed in a motor vehicle and used to transport or store motor vehicle fluids during the useful life of the motor vehicle.

[0046] The expression "the fluid residues present in the tubes and / or tanks have been completely or partially extracted before or after the comminution of the tubes and / or tanks" means that the tubes and / or tanks have been subjected to a treatment making it possible to partially or completely remove the fluids.

[0047] If the tubes and / or tanks transported air, this is for example the "air brake" pipe used for vehicle braking. Even if the air is completely removed after treatment, the fact remains that the pipe was exposed to engine heat and chemical agents such as ZnCl2 and therefore has the described oxidized functional groups, which distinguishes it from virgin pipe.

[0048] Throughout this specification the terms "tube" or "pipe" may be used and mean the same thing.

[0049] Thus, the recycled material represents used single and / or multi-layer tubes and / or tanks that originally transported or contained automotive vehicle fluids.

[0050] This does not, in any case, correspond to material resulting from the manufacturing process of the tubes or tanks, but rather to loss or scrap of material, or to tubes or tanks that do not meet specifications, have never transported motor vehicle fluids, and are subsequently reintroduced into the process.

[0051] For a composition comprising components a)+b)+c)+d)+e). The composition comprises: (a) 30% to 99.8% (by weight), in particular 50% to 99.8% (by weight), of recycled material from used mono- and / or multi-layer tubes and / or tanks, said tubes and / or said tanks consisting of a composition mainly comprising at least one polyamide, recycled materials, in which the used single-wall and / or multi-wall tubes and / or the used tanks have only been crushed into granules, the fluid residues present in the tubes and / or tanks being fully or partially extracted before or after crushing of the tubes and / or tanks; (b) up to 70%, in particular up to 50%, semicrystalline aliphatic polyamides; (c) up to 45% (by weight) of at least one impact modifier, in particular from 1% to 45% (by weight) of at least one impact modifier, in particular from 2% to 45% (by weight) of at least one impact modifier; (d) up to 20% (by weight) of at least one plasticizer; (e) up to 0.2% of additives, The sum of components a) + b) + c) + d) + e) ​​equals 100%.

[0052] The polyamide of the used tube and / or the used tank has a greater molar ratio of functional groups resulting from an oxidation reaction selected from primary amide functional groups, nitriles, terminal methyl groups, alkenes, formamides, imides, carboxylic acids and alcohols, and mixtures thereof, to amide functional groups than the same polyamide comprising a virgin tube and / or tank that has not yet transported or contained a motor vehicle fluid.

[0053] The term "fluid" refers to a gas or liquid used in a motor vehicle, in particular air, oil, water, a urea solution, a glycol-based coolant, or a fuel, such as gasoline, in particular alcohol-blended gasoline, biogasoline or diesel, in particular biodiesel, or hydrogen.

[0054] Advantageously, said fluid means a fuel, in particular a gasoline, in particular an alcohol blended gasoline, a biogasoline or a diesel, in particular a biodiesel.

[0055] The term "gasoline" means a mixture of hydrocarbons derived from the distillation of petroleum, to which additives or alcohols such as methanol or ethanol may be added, and in some cases alcohol may be the predominant component.

[0056] The expression "alcohol blended gasoline" means gasoline to which methanol or ethanol has been added. It also means gasoline of the E95 type that does not contain any petroleum distillate products.

[0057] The term "polyamide-based" means at least 50% (by weight) of polyamide in the layer.

[0058] The semi-crystalline aliphatic polyamides used in b) may contain impact modifiers and / or plasticizers and / or additives.

[0059] The oxidation reaction or mechanism corresponds in particular to the oxidation of an amide function and / or a methylene alpha (α) to said amide function.

[0060] Thus, used tubes and / or tanks (single and / or multi-layer for both tubes and tanks) to be reused or in other words recycled are removed from the motor vehicle, in particular from the automobile, and crushed.

[0061] Advantageously, it is subjected to only grinding, excluding reformulation with or without subsequent reformulation after grinding.

[0062] Such recompounding is conventionally carried out by introducing the ground material at least once into an extruder, in particular of the twin-screw co-rotating or co-kneader (Buss) type, where the ground material is remixed by melting with or without the addition of at least one compound selected from the semicrystalline aliphatic polyamide, whether of recycled origin or not, at least one impact modifier, plasticizer, additive and antistatic filler. The molten material leaves the extruder as a rod, is cooled, cut into pellets and then fed into the extruder to produce monolayer or multilayer tubular structures.

[0063] Alternatively, fluid residues present in the tubes and / or tanks may be fully or partially extracted before or after the comminution of the tubes and / or tanks.

[0064] In the first embodiment, the molar ratio of the functional groups generated by the oxidation reaction is in the range of 1 / 10000 to 1 / 20.

[0065] The concentration can be measured by proton or carbon NMR in dichloromethane-d2 with the addition of HFIP (hexafluoroisopropanol) to dissolve the polyamide.

[0066] In a first variant, said molar ratio of imide functions ranges from 1 / 1000 to 1 / 20, in particular from 1 / 500 to 1 / 20 and in particular from 1 / 200 to 1 / 50.

[0067] In a second variant, said molar ratio of carboxylic acid functions ranges from 1 / 5000 to 1 / 20, in particular from 1 / 3000 to 1 / 50 and very advantageously from 1 / 500 to 1 / 15.

[0068] In a third variant, said molar ratio of alcohol functions ranges from 1 / 1000 to 1 / 20, advantageously from 1 / 1000 to 1 / 25 and very advantageously from 1 / 200 to 1 / 50.

[0069] In a fourth variant, said molar ratio of primary amide functions ranges from 1 / 2000 to 1 / 20, advantageously from 1 / 1000 to 1 / 100 and very advantageously from 1 / 1000 to 1 / 500.

[0070] In a fifth variant, said molar ratio of nitrile functions ranges from 1 / 1000 to 1 / 20, advantageously from 1 / 500 to 1 / 15 and very advantageously from 1 / 100 to 1 / 10.

[0071] In a sixth variant, said molar ratio of terminal methyl functions ranges from 1 / 5000 to 1 / 50, advantageously from 1 / 2000 to 1 / 100 and very advantageously from 1 / 1000 to 1 / 200.

[0072] In these different variants, the ratio of the functional groups is calculated as a function of the integral of the secondary amide peak.

[0073] Since the composition consists of at most 99.8% recycled materials, it is necessary to add polyamides (same or different) of non-recycled origin to the recycled materials and / or impact modifiers and / or plasticizers and / or optionally additives. This can be done by dry blending (a mixture of recycled ground materials and virgin granules (whether formulated or not) and / or optionally additives) or by compounding, advantageously by dry blending.

[0074] This dry mix is ​​then introduced into an extruder during the production of single or multi-layer tubular structures.

[0075] The nomenclature used to define polyamides is described in standard ISO 1874-1:2011 "Plastics - Polyamide (PA) molding and extrusion materials - Part 1: Nomenclature" and is well known to those skilled in the art.

[0076] For the purposes of the present invention, the term "polyamide" refers to either a homopolyamide or a copolyamide.

[0077] For the purposes of the present invention, the term "semicrystalline polyamide" throughout this specification denotes a polyamide having a melting point (Tm) and a heat of fusion ΔH > 25 J / g, in particular > 40 J / g, especially > 45 J / g, determined by DSC according to standards ISO 11357-1:2016 and ISO 11357-2 and 3:2013 at a heating rate of 20 K / min, and a glass transition temperature (Tg).

[0078] The at least one aliphatic semicrystalline polyamide results from the polycondensation of at least one lactam, or from the polycondensation of at least one amino acid, or from the polycondensation of at least one diamine X with at least one dicarboxylic acid Y.

[0079] When said at least one aliphatic semicrystalline polyamide results from the polycondensation of at least one lactam, said at least one lactam may be selected from C6 to C18, preferentially C10 to C18 and more preferentially C10 to C12 lactams. The C6 to C18 lactam is in particular caprolactam, decanolactam, undecanolactam or lauryllactam.

[0080] When said at least one aliphatic semicrystalline polyamide results from the polycondensation of at least one lactam, it may comprise a single lactam or several lactams.

[0081] Advantageously, said at least one aliphatic semicrystalline polyamide results from the polycondensation of a single lactam, said lactam being chosen from lauryllactam and undecanolactam, advantageously lauryllactam.

[0082] When said at least one aliphatic semicrystalline polyamide results from the polycondensation of at least one amino acid, said at least one amino acid may be selected from C6 to C18, preferentially C10 to C18 and more preferentially C10 to C12 amino acids.

[0083] C6-C18 amino acids are especially 6-aminohexanoic acid, 9-aminononanoic acid, 10-aminodecanoic acid, 10-aminoundecanoic acid, 12-aminododecanoic acid and 11-aminoundecanoic acid and derivatives thereof, especially N-heptyl-11-aminoundecanoic acid.

[0084] When said at least one aliphatic semicrystalline polyamide results from the polycondensation of at least one amino acid, it may comprise a single amino acid or several amino acids.

[0085] Advantageously, said aliphatic semicrystalline polyamide results from the polycondensation of a single amino acid, said amino acid being chosen from 10-aminodecanoic acid, 11-aminoundecanoic acid and 12-aminododecanoic acid, advantageously 11-aminoundecanoic acid.

[0086] When said at least one aliphatic semicrystalline polyamide results from the polycondensation of at least one C4-C36, preferentially C5-C18, preferentially C5-C12, more preferentially C10-C12 diamine X with at least one C4-C36, preferentially C6-C18, preferentially C6-C12, more preferentially C10-C12 diacid Y, said at least one diamine X is an aliphatic diamine and said at least one diacid Y is an aliphatic diacid.

[0087] The diamine may be linear or branched. Advantageously, it is linear.

[0088] The at least one C4-C36 diamine X may be chosen in particular from 1,4-butanediamine, 1,5-pentamethylenediamine, 1,6-hexamethylenediamine, 1,7-heptamethylenediamine, 1,8-octamethylenediamine, 1,9-nonamethylenediamine, 1,10-decamethylenediamine, 1,11-undecamethylenediamine, 1,12-dodecamethylenediamine, 1,13-tridecamethylenediamine, 1,14-tetradecamethylenediamine, 1,16-hexadecamethylenediamine and 1,18-octadecamethylenediamine, octadecenediamine, eicosanediamine, docosanediamine, and diamines derived from fatty acids.

[0089] Advantageously, said at least one diamine X is C5-C18 and is chosen from 1,5-pentamethylenediamine, 1,6-hexamethylenediamine, 1,7-heptamethylenediamine, 1,8-octamethylenediamine, 1,9-nonamethylenediamine, 1,10-decamethylenediamine, 1,11-undecamethylenediamine, 1,12-dodecamethylenediamine, 1,13-tridecamethylenediamine, 1,14-tetradecamethylenediamine, 1,16-hexadecamethylenediamine and 1,18-octadecamethylenediamine.

[0090] Advantageously, said at least one diamine X is C5-C12 and is in particular chosen from 1,5-pentamethylenediamine, 1,6-hexamethylenediamine, 1,7-heptamethylenediamine, 1,8-octamethylenediamine, 1,9-nonamethylenediamine, 1,10-decamethylenediamine, 1,11-undecamethylenediamine and 1,12-dodecamethylenediamine.

[0091] Advantageously, said at least one diamine X is C6-C12 and is in particular chosen from 1,6-hexamethylenediamine, 1,7-heptamethylenediamine, 1,8-octamethylenediamine, 1,9-nonamethylenediamine, 1,10-decamethylenediamine, 1,11-undecamethylenediamine and 1,12-dodecamethylenediamine.

[0092] Advantageously, the diamine X used is a C10-C12 diamine, in particular chosen from 1,10-decamethylenediamine, 1,11-undecamethylenediamine and 1,12-dodecamethylenediamine.

[0093] The at least one C4-C36 dicarboxylic acid Y may be selected from succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, brassylic acid, tetradecanedioic acid, pentadecanedioic acid, hexadecanedioic acid, octadecanedioic acid, and diacids derived from fatty acids.

[0094] The diacid may be linear or branched. Advantageously, it is linear.

[0095] Advantageously, said at least one dicarboxylic acid Y is C6-C18 and is chosen from adipic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, brassylic acid, tetradecanedioic acid, pentadecanedioic acid, hexadecanedioic acid and octadecanedioic acid.

[0096] Advantageously, said at least one dicarboxylic acid Y is C6-C12 and is chosen from adipic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid and dodecanedioic acid.

[0097] Advantageously, said at least one dicarboxylic acid Y is C10-C12 and is chosen from sebacic acid, undecanedioic acid and dodecanedioic acid.

[0098] When said aliphatic semicrystalline polyamide results from the polycondensation of at least one diamine X with at least one dicarboxylic acid Y, it may therefore comprise a single diamine or several diamines and a single dicarboxylic acid or several dicarboxylic acids.

[0099] Advantageously, said aliphatic semicrystalline polyamide results from the polycondensation of a single diamine X with a single dicarboxylic acid Y.

[0100] The term "predominantly comprising at least one aliphatic type polyamide" means that the composition of layer (1) comprises at least 50% (by weight) of at least one aliphatic polyamide relative to the total weight of the composition.

[0101] Advantageously, said composition of layer (1) comprises at least 60% (by weight), in particular at least 70% (by weight), in particular at least 80% (by weight) and more particularly at least 90% (by weight) of at least one aliphatic polyamide relative to the total weight of said composition.

[0102] The composition of layer (1) consists of at least 30%, in particular at least 50% and up to 99.8% recycled material from single-wall and / or multi-wall tubes and / or tanks, said tubes and tanks being post-consumer components and intended for transporting or storing motor vehicle fluids.

[0103] This means that either the "at least one main polyamide" of said composition corresponds in its entirety to what is referred to as "at least 50% recycled material" or at least 50% (by weight) of the total components of the composition are of recycled origin from single-wall tubes, or multi-layer tubes, or tanks, or mixtures thereof.

[0104] The recycled material may be obtained from monolayer and / or multilayer tubes and / or monolayer and / or multilayer tanks, said monolayer and / or multilayer tubes being used components and intended to transport motor vehicle fluids and / or said monolayer and / or multilayer tanks being used components and intended to store motor vehicle fluids. The tubes or tanks are therefore used tubes or tanks, i.e. used for at least one year for the transport or storage of said fluids as defined above. The monolayer tubes consist of a composition comprising a semicrystalline aliphatic polyamide and optionally impact modifiers and / or additives and / or plasticizers and / or antistatic fillers.

[0105] The multi-layer tube comprises at least one layer of a composition comprising a semi-crystalline aliphatic polyamide and, optionally, an impact modifier and / or additive, and may therefore comprise other layers of thermoplastic polymers other than semi-crystalline aliphatic polyamides, such as polyethylene, polypropylene, semi-aromatic polyamides or polyethylene vinyl alcohol (EVOH).

[0106] Said tank may be monolayer and may consist of a composition comprising a semi-crystalline aliphatic polyamide and optionally impact modifiers and / or additives and / or plasticizers and / or antistatic fillers.

[0107] The tank may be multi-layered, comprising at least one layer of a composition comprising a semi-crystalline aliphatic polyamide and, optionally, impact modifiers and / or additives, and may therefore comprise other layers of thermoplastic polymers other than semi-crystalline aliphatic polyamides, such as polyethylene, polypropylene, semi-aromatic polyamides or polyethylene vinyl alcohol (EVOH).

[0108] Of course, the monolayer tube may also be a monolayer blend, ie, for example, two monolayer tubes, each made of a different semicrystalline aliphatic polyamide, such as PA11 and PA12.

[0109] It will also be appreciated that the multi-layer tube may also be a mixture of different multi-layer tube types, provided that at least one of the layers of one of the multi-layer tube types consists of a semi-crystalline aliphatic polyamide.

[0110] It will also be appreciated that the monolayer tank may also be a monolayer tank blend, i.e. for example two monolayer tanks each made of a different semicrystalline aliphatic polyamide, such as PA11 and PA12.

[0111] It will also be appreciated that the multi-layer tank may also be a mixture of different multi-layer tank types, provided that at least one of the layers of one of the multi-layer tank types consists of a semi-crystalline aliphatic polyamide.

[0112] If the mixing tubes or tanks are not compatible with each other, there is the addition of a third semi-crystalline aliphatic polyamide, designated B, having an average number of carbon atoms per nitrogen atom CB, to make them compatible.

[0113] If A is indicated as the polyamide of the tube and C as the polyamide of the tank, and they do not match: CB is (C A +C C ) / 2-2 and (C A +C C ) / 2+2, favorably (C A +C C ) / 2-1 and (C A +C C ) / 2+1.

[0114] The monolayer and / or multilayer tubes, which have been used to transport motor vehicle fluids and are therefore post-consumer components, may be subjected to a number of different processes to enable them to be recycled.

[0115] The fluid residue is first fully or partially extracted and then the single and / or multi-layer tubes and / or tanks are crushed, or the single and / or multi-layer tubes and / or tanks are crushed and then the fluid residue is fully or partially extracted from the resulting crushed material.

[0116] In one embodiment, the extraction of said fluid residues is performed by washing or ventilation.

[0117] The washing may be carried out either before or after the grinding.

[0118] Advantageously, washing is carried out using a fluid such as supercritical CO2 or a solvent such as methanol, ethanol, in particular methanol, or a mixture of supercritical CO2 and a solvent.

[0119] This washing allows, among other things, the removal of fluids that are miscible with methanol, such as fuels, oils and coolants.

[0120] Advantageously, ventilation is performed by means of an inerting oven or desiccator.

[0121] In one embodiment, extraction is carried out after comminution by a degassing zone in said extruder or by other equipment allowing degassing in the molten state.

[0122] Advantageously, the spent pipe is cleaned before or after grinding to remove any residual oligomers that may be present in the spent pipe.

[0123] Fluids such as fuel, when stored in tanks or transported in tubes, degrade the polymers of the constituent layers of the tubes in contact with the fluid, resulting in the appearance of oligomers that must be cleaned before the tubes can be recycled.

[0124] The oligomers are cleaned by washing with water or a polar solvent such as methanol or ethanol.

[0125] For example, PA6 and 66 are systematically washed in hot water (approximately 100-120°C) to remove as much caprolactam as possible.

[0126] Alternatively, the oligomers may be distilled.

[0127] In the case of extraction by ventilation, this operation can be carried out after comminution in an inerting oven or during extrusion of the tubular structure if the extruder is equipped with a degassing zone.

[0128] The fluid residue may be any fluid that was originally transported by the single or multi-layer tube or stored in a tank.

[0129] Extraction may also be carried out before or after milling, for example by placing under reduced pressure if the fluid residue is volatile.

[0130] In one embodiment, the composition comprises: (a) 30% to 99.8% (by weight), in particular 50% to 99.8% (by weight), of recycled material from used single-wall and / or multi-wall tubes and / or tanks that originally transported or contained motor vehicle fluids, in particular air, oil, water, urea solutions, glycol-based coolants, or fuels, such as gasoline, in particular alcohol-blended gasoline, biogasoline or diesel, in particular biodiesel, or hydrogen, said tubes and / or said tanks consisting of a composition that mainly comprises at least one polyamide, recycled material, in which the used single-wall and / or multi-wall tubes and / or the used tanks have been crushed into granules and the fluid residues present in the tubes and / or tanks have been fully or partially extracted before or after crushing of the tubes and / or tanks; (b) up to 70%, in particular up to 50%, semicrystalline aliphatic polyamides; (c) up to 45% (by weight) of at least one impact modifier, in particular from 1% to 45% (by weight) of at least one impact modifier, in particular from 2% to 45% (by weight) of at least one impact modifier; (d) up to 20% (by weight) of at least one plasticizer; (e) up to 0.2% of additives; The sum of components a) + b) + c) + d) + e) ​​equals 100%.

[0131] In another embodiment, the composition comprises: (a) 30% to 99.8% (by weight), in particular 50% to 99.8% (by weight), of recycled material from used single-wall and / or multi-wall tubes and / or tanks that originally transported or contained motor vehicle fluids, in particular air, oil, water, urea solutions, glycol-based coolants, or fuels, such as gasoline, in particular alcohol-blended gasoline, biogasoline or diesel, in particular biodiesel, or hydrogen, said tubes and / or said tanks consisting of a composition predominantly consisting of at least one polyamide, recycled material, in which the used single-wall and / or multi-wall tubes and / or the used tanks have been crushed into granules and the fluid residues present in the tubes and / or tanks have been fully or partially extracted before or after crushing of the tubes and / or tanks; (b) up to 70%, in particular up to 50%, semicrystalline aliphatic polyamides; (c) up to 45% (by weight) of at least one impact modifier, in particular from 1% to 45% (by weight) of at least one impact modifier, in particular from 2% to 45% (by weight) of at least one impact modifier; (d) up to 20% (by weight) of at least one plasticizer; (e) up to 0.2% of additives; The sum of components a) + b) + c) + d) + e) ​​equals 100%.

[0132] Advantageously, in these last two embodiments, the used single-layer and / or multi-layer tubes and / or the used tanks are only crushed, excluding any reconstitution with or without subsequent reformulation after crushing.

[0133] Advantageously, in these last three embodiments, said tube and / or said tank consist of a composition made of at least one polyamide.

[0134] According to a first variant, the composition comprises the above mentioned components a)+b)+c)+d)+e) in the following proportions: (a) 30% to 87.8% (by weight), in particular 50% to 87.8% (by weight), of recycled material from used single-wall and / or multi-wall tubes and / or tanks that originally transported or contained motor vehicle fluids, in particular air, oil, water, urea solutions, glycol-based coolants, or fuels, such as gasoline, in particular alcohol-blended gasoline, biogasoline or diesel, in particular biodiesel, or hydrogen, wherein the tubes and / or the tanks consist of a composition that mainly comprises at least one polyamide, (b) 10% to 70%, in particular 10% to 50%, of a semicrystalline aliphatic polyamide; (c) 1% to 45% (by weight) of at least one impact modifier, in particular 2% to 45% (by weight) of at least one impact modifier; (d) 1% to 20% (by weight) of at least one plasticizer; (e) up to 0.2% of additives, The sum of components a) + b) + c) + d) + e) ​​equals 100%.

[0135] According to a second variant, the composition comprises the above mentioned components a)+b)+c)+d)+e) in the following proportions: (a) 30% to 87.8% (by weight), in particular 50% to 87.8% (by weight), of recycled material from used single-wall and / or multi-wall tubes and / or tanks that originally transported or contained motor vehicle fluids, in particular air, oil, water, urea solutions, glycol-based coolants, or fuels, such as gasoline, in particular alcohol-blended gasoline, biogasoline or diesel, in particular biodiesel, or hydrogen, wherein the tubes and / or the tanks consist of a composition that mainly comprises at least one polyamide, (b) 10% to 70%, in particular 10% to 50%, of a semicrystalline aliphatic polyamide; (c) 1% to 45% (by weight) of at least one impact modifier, in particular 2% to 45% (by weight) of at least one impact modifier; (d) 1% to 20% (by weight) of at least one plasticizer; (e) up to 0.2% of additives; The sum of components a) + b) + c) + d) + e) ​​equals 100%.

[0136] Advantageously, in these two variants, said used single-layer and / or multi-layer tubes and / or said used tanks are only crushed, excluding reformulation with or without subsequent reformulation after crushing.

[0137] In these two variants and in the related embodiments, advantageously, said tubes and / or tanks consist mainly of a composition consisting of at least one polyamide; in particular of at least one polyamide.

[0138] According to another aspect, the present invention relates to a single or multi-layer tubular structure (MLT) intended for transporting motor vehicle fluids, in particular air, oil, water, urea solutions, glycol-based coolants, or fuels, such as gasoline, in particular alcohol-blended gasoline, biogasoline or diesel, in particular biodiesel, or hydrogen, comprising at least one layer (1) of the composition defined above.

[0139] In one embodiment, the tubular structure is adapted to provide a maximum ion exchange rate of 0.3 g / m during initial storage of gasoline, particularly alcohol blended gasoline. 2 of insoluble extract, advantageously up to 0.2 g / m 2 Yes.

[0140] In one embodiment, the tubular structure has 30%, particularly 40%, and especially 50% less insoluble extractables during initial storage of gasoline, particularly alcohol-blended gasoline, than the same tubular structure made from non-recycled materials.

[0141] The monolayer tubular structure of the invention, intended for the transport of motor vehicle fluids, makes it possible to significantly reduce the percentage of extractables, as determined by a test consisting of filling the tubular structure with an alcohol blended gasoline of the FAM-B type, heating the assembly at 60°C for 96 hours, and then emptying the assembly by filtering the fluid into a beaker.

[0142] The insoluble extractables present on the filter during filtration, weighed after drying, are less than 0.3 g / m2.

[0143] The soluble extractables are quantified by evaporating the filtrate in the beaker at room temperature and then weighing the residue. The proportion of soluble extractables is advantageously less than or equal to about 15 g / m2 of the internal surface area of ​​the tube.

[0144] Alcohol blended gasoline FAM B is described in the standards DIN 51604-1:1982, DIN 51604-2:1984 and DIN 51604-3:1984.

[0145] Briefly, an alcohol blended gasoline FAM A is first prepared using a mixture of 50% toluene, 30% isooctane, 15% diisobutylene and 5% ethanol, and then FAM B is prepared by mixing 84.5% FAM A with 15% methanol and 0.5% water.

[0146] FAM B consists of a total of 42.3% toluene, 25.4% isooctane, 12.7% diisobutylene, 4.2% ethanol, 15% methanol and 0.5% water.

[0147] The tubular structure has a lower extractables content during initial storage of gasoline, particularly alcohol-blended gasoline, than an identical tubular structure made from non-recycled, i.e., virgin or original materials, and in particular has a proportion of insoluble extractables that is 30%, particularly 40%, in particular 50% lower than the proportion present in the identical tubular structure made from non-recycled or virgin materials.

[0148] About layer (1) Layer (1) consists mainly of a composition comprising at least one semi-crystalline aliphatic polyamide, said composition consisting of at least 30%, in particular at least 50%, recycled material originating from mono- and / or multi-layer tubes used for transporting motor vehicle fluids and / or from mono- and / or multi-layer tanks used for storing motor vehicle fluids.

[0149] Since the composition of layer (1) consists of at most 99.8% recycled materials, polyamides (same or different) of non-recycled origin must be added to the recycled materials, which is then carried out during the passage through the extruder during the manufacture of the single- or multi-layer tubular structures and / or additives.

[0150] In a first variant, said composition of layer (1) is a) at least 50% (by weight), in particular 50% to 99.8% (by weight), C C at least one semicrystalline aliphatic polyamide, denoted by C, having an average number of carbon atoms per nitrogen atom of from 6 to 18, advantageously from 8 to 12; b1) 0 to 50% (by weight) of C B = Cc-1, preferentially C B = at least one semicrystalline aliphatic polyamide, denoted by B, having an average number of carbon atoms per nitrogen atom, denoted by Cc-2; b2) 0 to 50% (by weight) of C A =C B -1, C as a priority A =C B semicrystalline aliphatic polyamides, denoted by A, having an average number of carbon atoms per nitrogen atom, denoted by -2; c) 0 to 45% (by weight) of at least one impact modifier, in particular 1% to 45% (by weight) of at least one impact modifier, in particular 2% to 45% (by weight) of at least one impact modifier; d) 0-20% (by weight) of at least one plasticizer; e) 0 to 0.2% (by weight) of at least one additive; The sum of components a), b1), b2), c), d) and e) equals 100%.

[0151] Advantageously, in this first variant, the composition of layer (1) comprises: b1) 1% to 50% (by weight) of C B = Cc-1, preferentially C B = At least one semi-crystalline aliphatic polyamide, denoted B, having an average number of carbon atoms per nitrogen atom, denoted Cc-2.

[0152] Advantageously, in this first variant, the composition of layer (1) comprises b2) 1% to 50% (by weight) of C A =C B -1, C as a priority A =C B The polyamide composition includes a semi-crystalline aliphatic polyamide represented by A having an average number of carbon atoms per nitrogen atom represented by -2.

[0153] Advantageously, in this first variant, the composition of layer (1) comprises: b1) 1% to 50% (by weight) of C B = Cc-1, preferentially C B At least one semi-crystalline aliphatic polyamide represented by B having an average number of carbon atoms per nitrogen atom represented by Cc-2 = Cc-2, and b2) 1% to 50% (by weight) of A =C B -1, C as a priorityA =C B The polyamide composition includes a semi-crystalline aliphatic polyamide represented by A having an average number of carbon atoms per nitrogen atom represented by -2.

[0154] Advantageously, in this first variant, said composition of layer (1) comprises c) between 1% and 45% (by weight) of at least one impact modifier, in particular between 2% and 45% (by weight) of at least one impact modifier.

[0155] Advantageously, in this first variant, said composition of layer (1) comprises d) between 1% and 20% (by weight) of at least one plasticizer.

[0156] Advantageously, in this first variant, said composition of layer (1) comprises e) between 1% and 0.2% (by weight) of at least one additive.

[0157] All combinations of a), b1), b2), c), d) and e) defined above are possible in this first variant.

[0158] In a second variant, said composition of layer (1) is a) at least 50% (by weight), in particular 50% to 99.8% (by weight), C C at least one semicrystalline aliphatic polyamide, denoted by C, having an average number of carbon atoms per nitrogen atom of from 6 to 18, advantageously from 8 to 12; b1) 0 to 25% (by weight) of C B = Cc-1, preferentially C B = at least one semicrystalline aliphatic polyamide, denoted by B, having an average number of carbon atoms per nitrogen atom, denoted by Cc-2; b2) 0 to 25% (by weight) of C A =C B -1, C as a priority A =C B semicrystalline aliphatic polyamides, denoted by A, having an average number of carbon atoms per nitrogen atom, denoted by -2; c) 0 to 45% (by weight) of at least one impact modifier, in particular 1% to 45% (by weight) of at least one impact modifier, in particular 2% to 45% (by weight) of at least one impact modifier; d) 0-20% of at least one plasticizer; e) 0 to 0.2% (by weight) of at least one additive; The sum of components a), b1), b2), c), d) and e) equals 100%.

[0159] All embodiments described for the first variant are also valid for this second variant.

[0160] The polyamides denoted A, B and C may be of recycled or non-recycled origin, provided that the composition of layer (1) consists of at least 50% recycled material.

[0161] Advantageously, the Tm of the predominant semicrystalline aliphatic polyamide of layer (1) is ≦225° C., in particular ≦200° C., at a heating rate of 20 K / min, determined according to ISO 11357-3:2013.

[0162] In one embodiment, said composition of layer (1) does not comprise any plasticizers and / or impact modifiers.

[0163] In another embodiment, said composition of layer (1) comprises at least one compound selected from plasticizers, impact modifiers and additives, and said recycled material is selected from crushed tubes.

[0164] Advantageously, in these last two embodiments, said tube is a single-wall tube and / or a multi-wall tube.

[0165] In one embodiment, the fluid transported by the single layer and / or multi-layer tubes or stored in the tank is different from the fluid in the multi-layer tubular structure (MLT).

[0166] This means that the MLT may be intended to transport gasoline when the single and / or multi-layer tubes transport a fluid such as air, or further, the MLT may be intended to transport diesel when the single and / or multi-layer tubes transport a fluid such as alcohol blended gasoline.

[0167] The same is true for tanks.

[0168] In another embodiment, the fluid transported by the single layer and / or multi-layer tubes or stored in the tank is the same as the fluid in the multi-layer tubular structure (MLT).

[0169] This means that if the single and / or multi-layer tube transports a fluid such as gasoline, the MLT may be intended to transport gasoline (provided that the gasoline in the single and / or multi-layer tube and the MLT is the same (e.g. alcohol blended gasoline).

[0170] The same is true for tanks.

[0171] Advantageously, the recycled material originates from a monolayer tube of a composition comprising only PA11.

[0172] Of course, the PA11 may be formulated.

[0173] In one embodiment, the composition of layer (1) comprises at least 60% (by weight), in particular at least 70% (by weight), in particular at least 80% (by weight), in particular at least 90% (by weight), more particularly at least 95% (by weight) of recycled material, but not more than 99.8%.

[0174] The recycled material can be mixed with virgin polyamide containing additives or with a masterbatch containing large amounts of additives.

[0175] Recycled used single or multi-layer tubes or tanks The used tubes or tanks intended for transporting or storing motor vehicle fluids are crushed by extraction of the fluid residues before or after crushing, and the composition of layer (1) resulting from the recycling is a) at least 50% (by weight), in particular from 50% to 99.8% (by weight), of at least one semicrystalline aliphatic polyamide, designated C, having an average number of carbon atoms per nitrogen atom, designated CC, of ​​6 to 18, advantageously 8 to 12; b1) 0-25% (by weight) of at least one semicrystalline aliphatic polyamide, denoted B, having an average number of carbon atoms per nitrogen atom denoted CB=Cc-1, preferentially CB=Cc-2; b2) 0-25% (by weight) of semicrystalline aliphatic polyamides, denoted A, having an average number of carbon atoms per nitrogen atom, denoted CA=CB-1, preferentially CA=CB-2; c) 0 to 45% (by weight) of at least one impact modifier, in particular 1% to 45% (by weight) of at least one impact modifier, in particular 2% to 45% (by weight) of at least one impact modifier; d) 0-20% (by weight) of at least one plasticizer; e) 0 to 0.2% (by weight) of at least one additive; The sum of the components is equal to 100%. Advantageously, the semicrystalline aliphatic polyamide denoted C is chosen from PA612, PA1012, PA1010, PA11 and PA12, and especially PA11.

[0176] Advantageously, it is only milled, precluding reformulation with or without subsequent reformulation after milling.

[0177] Advantageously, said used tube or said tank is intended to transport or store fuels such as gasoline, in particular alcohol blended gasoline, biogasoline or diesel, in particular biodiesel.

[0178] Advantageously, the semi-crystalline aliphatic polyamide designated C is selected from PA612, PA1012, PA1010, PA11 and PA12, in particular PA11, and said tube is intended to transport fuels such as gasoline, in particular alcohol-blended gasoline, biogasoline or diesel, in particular biodiesel.

[0179] Advantageously, the tubes or the tanks intended to transport or store motor vehicle fluids are monolayered, and advantageously the tubes and the tanks are blends ranging from 5 / 95 to 95 / 5 (by weight).

[0180] In a first variant, the used tubes or tanks intended for transporting or storing motor vehicle fluids are crushed by extraction of the fluid residues before or after crushing, and the composition of layer (1) resulting from the recycling consists of the composition defined for the first variant and its related embodiments described in the section "Regarding layer (1)" above.

[0181] In a second variant, the used tubes or tanks intended for transporting or storing motor vehicle fluids are crushed by extraction of the fluid residues before or after crushing, and the composition of layer (1) resulting from the recycling consists of the composition defined for the second variant and its related embodiments described in the section "Regarding layer (1)" above.

[0182] About layer (2) In one embodiment, the structure is multi-layered and includes at least one layer (2).

[0183] In one embodiment, the multi-layer tubular structure comprises at least one layer (2) consisting of a composition predominantly comprising at least one semi-crystalline, semi-aromatic aliphatic polyamide or polyolefin.

[0184] Advantageously, said layer (2) consists of at least 90% non-recycled materials.

[0185] The terms "semicrystalline polyamide" and "aliphatic" have the same definition as in layer (1).

[0186] Said at least one semicrystalline aliphatic polyamide is obtained in the same manner as described above for layer (1).

[0187] The semi-aromatic polyamide is as defined below.

[0188] The polyolefin is as defined below for impact modifier polyolefin.

[0189] In a first variant, said layer (2) consists of a composition mainly comprising at least one semicrystalline aliphatic polyamide and optionally at least one impact modifier, When layer (2) consists of a composition mainly comprising at least one semi-crystalline aliphatic polyamide, which is PA12 and / or PA610 and / or PA612 and / or PA1010 and / or PA6, said composition comprises said impact modifier and said layer (2) consists of at least 90% non-recycled materials.

[0190] In one embodiment of this first variant, said layer (2) does not comprise an impact modifier.

[0191] In this case, the semicrystalline aliphatic polyamides PA12 and / or PA610 and / or PA612 and / or PA1010 and / or PA6 are excluded from the composition constituting the layer (2).

[0192] In another embodiment of this first variant of layer (2), said layer (2) comprises c) between 3% and 45% (by weight) of at least one impact modifier, in particular between 5% and 20% (by weight) of at least one impact modifier.

[0193] In yet another embodiment of this first variant, said layer (2) comprises a) at least 50% (by weight), in particular from 50% to 99.8% (by weight), of at least one semicrystalline aliphatic polyamide, denoted D, having an average number of carbon atoms per nitrogen atom, denoted CD, of 6 to 18, advantageously 9 to 15; b1) 0-25% (by weight) of at least one semicrystalline aliphatic polyamide, denoted E, having an average number of carbon atoms per nitrogen atom denoted CE=CD-1, preferentially CE=CD-2; b2) 0-25% (by weight) of semicrystalline aliphatic polyamides, denoted F, having an average number of carbon atoms per nitrogen atom denoted CF=CE-1, preferentially CF=CE-2; c) 3% to 45% (by weight) of at least one impact modifier, in particular 5% to 20% (by weight) of at least one impact modifier; d) 0-20% of at least one plasticizer; e) 0-0.2% (by weight) of at least one additive; f) 0-35% (by weight) of at least one antistatic filler; The sum of components a), b1), b2), c), d), e), and f) equals 100%.

[0194] Advantageously, in this first variant, said composition of layer (2) comprises b1) between 1% and 50% (by weight) of at least one semicrystalline aliphatic polyamide denoted E having an average number of carbon atoms per nitrogen atom denoted CE=CD-1, preferentially CE=CD-2.

[0195] Advantageously, in this first variant, said composition of layer (2) comprises b2) between 1% and 50% (by weight) of a semicrystalline aliphatic polyamide, denoted F, having an average number of carbon atoms per nitrogen atom denoted CF=CE-1, preferentially CF=CE-2.

[0196] Advantageously, in this first variant, said composition of layer (2) comprises b1) from 1% to 50% (by weight) of at least one semicrystalline aliphatic polyamide, denoted E, having an average number of carbon atoms per nitrogen atom with CE=CD-1, preferentially CE=CD-2, and b2) from 1% to 50% (by weight) of a semicrystalline aliphatic polyamide, denoted F, having an average number of carbon atoms per nitrogen atom with CF=CE-1, preferentially CF=CE-2.

[0197] Advantageously, in this first variant, said composition of layer (2) comprises d) between 1% and 20% (by weight) of at least one plasticizer.

[0198] Advantageously, in this first variant, said composition of layer (2) comprises e) between 1% and 0.2% (by weight) of at least one additive.

[0199] Advantageously, in this first variant, said composition of layer (2) comprises f) between 1% and 35% (by weight) of at least one antistatic filler.

[0200] All combinations of a), b1), b2), c), d), e) and f) defined above are possible in this first variant.

[0201] In a second variant, the layer (2) is a) at least 50% (by weight), in particular from 50% to 99.8% (by weight), of at least one semicrystalline aliphatic polyamide, denoted D, having an average number of carbon atoms per nitrogen atom, denoted CD, of 6 to 18, advantageously 9 to 15; b1) 0-25% (by weight) of at least one semicrystalline aliphatic polyamide, denoted E, having an average number of carbon atoms per nitrogen atom denoted CE=CD-1, preferentially CE=CD-2; b2) 0-25% (by weight) of semicrystalline aliphatic polyamides, denoted F, having an average number of carbon atoms per nitrogen atom denoted CF=CE-1, preferentially CF=CE-2; c) 3% to 45% (by weight) of at least one impact modifier, in particular 5% to 20% (by weight) of at least one impact modifier; d) 0-20% of at least one plasticizer; e) 0-0.2% (by weight) of at least one additive; f) 0-35% (by weight) of at least one antistatic filler; The sum of components a), b1), b2), c), d), e) and f) equals 100%.

[0202] All embodiments described for the first variant are also valid for this second variant.

[0203] Advantageously, the composition of said layer (2) of the first and second variants comprises PA11, PA12 or PA612 and between 3% and 45% (by weight) of impact modifier, in particular between 5% and 20% (by weight) of impact modifier.

[0204] In a third variant, said layer (2) consists of a composition mainly comprising at least one semi-aromatic polyamide.

[0205] In a fourth variant, said layer (2) consists of a composition mainly comprising at least one semi-aromatic polyamide.

[0206] Advantageously, said layer (2) consists of a composition consisting of at least one semi-aromatic polyamide.

[0207] In a fifth variant, said layer (2) consists of a composition mainly comprising at least one polyolefin.

[0208] In a sixth variant, said layer (2) consists of a composition mainly comprising at least one polyolefin.

[0209] Advantageously, said layer (2) consists of a composition consisting of at least one polyolefin.

[0210] Regarding layer (2') In one embodiment, the multilayer tubular structure comprises at least one layer (2') consisting of a composition mainly comprising at least one semi-crystalline aliphatic polyamide, semi-aromatic polyamide or polyolefin, said layer (2') consisting of at least 90% non-recycled materials.

[0211] The terms "semicrystalline polyamide" and "aliphatic" have the same definition as in layer (1) or layer (2).

[0212] Said at least one semicrystalline aliphatic polyamide is obtained in the same way as described above for layers (1) and (2). In a first variant of layer (2'), said layer (2') does not contain an impact modifier.

[0213] In a second variant of layer (2'), said layer (2') comprises between 3% and 45% (by weight) of at least one impact modifier, in particular between 5% and 20% (by weight) of at least one impact modifier.

[0214] In one embodiment of this second variant, said layer (2') comprises: a) at least 50% (by weight), in particular 50% to 97% (by weight), in particular 50% to 95% (by weight) of at least one semicrystalline aliphatic polyamide, denoted D, having an average number of carbon atoms per nitrogen atom, denoted CD, of 6 to 18, advantageously 9 to 15; b1) 0-25% (by weight) of at least one semicrystalline aliphatic polyamide, denoted E, having an average number of carbon atoms per nitrogen atom denoted CE=CD-1, preferentially CE=CD-2; b2) 0-25% (by weight) of semicrystalline aliphatic polyamides, denoted F, having an average number of carbon atoms per nitrogen atom denoted CF=CE-1, preferentially CF=CE-2; c) 3% to 45% (by weight) of at least one impact modifier, in particular 5% to 20% (by weight) of at least one impact modifier; d) 0-20% of at least one plasticizer; e) 0-2% (by weight) of at least one additive; f) 0-35% (by weight) of at least one antistatic filler; The sum of components a), b1), b2), c), d), e) and f) equals 100%.

[0215] Advantageously, in this last embodiment of this second variant, said composition of layer (2') comprises b1) between 1% and 50% (by weight) of at least one semicrystalline aliphatic polyamide denoted E, having an average number of carbon atoms per nitrogen atom denoted CE=CD-1, preferentially CE=CD-2.

[0216] Advantageously, in this last embodiment of this second variant, said composition of layer (2') comprises b2) between 1% and 50% (by weight) of a semicrystalline aliphatic polyamide denoted F, having an average number of carbon atoms per nitrogen atom denoted CF=CE-1, preferentially CF=CE-2.

[0217] Advantageously, in this last embodiment of this second variant, said composition of layer (2') comprises b1) from 1% to 50% (by weight) of at least one semicrystalline aliphatic polyamide, denoted E, having an average number of carbon atoms per nitrogen atom, denoted CE=CD-1, preferentially CE=CD-2, and b2) from 1% to 50% (by weight) of a semicrystalline aliphatic polyamide, denoted F, having an average number of carbon atoms per nitrogen atom, denoted CF=CE-1, preferentially CF=CE-2.

[0218] Advantageously, in this last embodiment of this second variant, said composition of layer (2') comprises d) between 1% and 20% (by weight) of at least one plasticizer.

[0219] Advantageously, in this last embodiment of this second variant, said composition of layer (2') comprises e) between 1% and 0.2% (by weight) of at least one additive.

[0220] Advantageously, in this last embodiment of this second variant, said composition of layer (2') comprises f) between 1% and 35% (by weight) of at least one antistatic filler.

[0221] All combinations of a), b1), b2), c), d), e) and f) defined above are possible in this last embodiment of this second variant.

[0222] In another embodiment of this second variant, said layer (2') comprises: a) at least 50% (by weight), in particular 50% to 97% (by weight), in particular 50% to 95% (by weight) of at least one semicrystalline aliphatic polyamide, denoted D, having an average number of carbon atoms per nitrogen atom, denoted CD, of 6 to 18, advantageously 9 to 15; b1) 0-25% (by weight) of at least one semicrystalline aliphatic polyamide, denoted E, having an average number of carbon atoms per nitrogen atom denoted CE=CD-1, preferentially CE=CD-2; b2) 0-25% (by weight) of semicrystalline aliphatic polyamides, denoted F, having an average number of carbon atoms per nitrogen atom denoted CF=CE-1, preferentially CF=CE-2; c) 3% to 45% (by weight) of at least one impact modifier, in particular 5% to 20% (by weight) of at least one impact modifier; d) 0-20% of at least one plasticizer; e) 0-2% (by weight) of at least one additive; f) 0-35% (by weight) of at least one antistatic filler; The sum of components a), b1), b2), c), d), e) and f) equals 100%.

[0223] All embodiments described above for the last embodiment of this second variant are also valid for this other embodiment of this second variant.

[0224] Advantageously, the composition of said layer (2') comprises PA11, PA12 or PA612 and from 3% to 45% (by weight) of at least one impact modifier, in particular from 5% to 20% (by weight) of at least one impact modifier.

[0225] In a third variant, said layer (2') consists of a composition mainly comprising at least one semi-aromatic polyamide.

[0226] Said at least one semi-aromatic semi-crystalline polyamide results from the polycondensation of at least one diamine X as defined above and at least one aromatic dicarboxylic acid, or of a diamine Xa and a dicarboxylic acid Y as defined above.

[0227] The aromatic dicarboxylic acid is advantageously chosen from terephthalic acid (written as T), isophthalic acid (written as I) and 2,6-naphthalenedicarboxylic acid (written as N) or mixtures thereof, in particular from terephthalic acid (written as T), isophthalic acid (written as I) or mixtures thereof.

[0228] The diamine Xa is advantageously an arylamine, which may be chosen from metaxylylenediamine (MXD, CAS number 1477-55-0) or paraxylylenediamine (PXD, CAS number 539-48-0).

[0229] When said semi-aromatic semi-crystalline polyamide results from the polycondensation of at least one diamine X with at least one aromatic dicarboxylic acid or of at least one diamine Xa with at least one dicarboxylic acid Y, it may comprise a single diamine or several diamines and a single dicarboxylic acid or several dicarboxylic acids.

[0230] Advantageously, said semicrystalline, semiaromatic polyamide results from the polycondensation of a single diamine X with a single aromatic dicarboxylic acid or from the polycondensation of a single diamine Xa with a single dicarboxylic acid Y.

[0231] Advantageously, said semicrystalline, semiaromatic polyamide results from the polycondensation of at least one diamine X with at least one dicarboxylic acid chosen from terephthalic acid and isophthalic acid, in particular terephthalic acid, or said semicrystalline, semiaromatic polyamide results from the polycondensation of at least one diamine Xa with at least one dicarboxylic acid Y.

[0232] In particular, the at least one C6-C12 diamine X is selected from 1,6-hexamethylenediamine, 1,7-heptamethylenediamine, 1,8-octamethylenediamine, 1,9-nonamethylenediamine, 1,10-decamethylenediamine, 1,11-undecamethylenediamine and 1,12-dodecamethylenediamine, and the at least one dicarboxylic acid is an acid selected from terephthalic acid and isophthalic acid, especially terephthalic acid.

[0233] In particular, the at least one diamine Xa is an arylamine selected from metaxylylenediamine (MXD, CAS number: 1477-55-0) or paraxylylenediamine (PXD, CAS number: 539-48-0) and the at least one dicarboxylic acid Y is C6-C18 and is selected from adipic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, brassylic acid, tetradecanedioic acid, pentadecanedioic acid, hexadecanedioic acid and octadecanedioic acid.

[0234] Advantageously, said at least one dicarboxylic acid Y is C6-C12 and is chosen from adipic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid and dodecanedioic acid.

[0235] Each of these semi-aromatic polyamides may be copolymerized with a lactam or an amino acid to give structures such as PA10 / 10T, PA10 / 9T, PA10 / 12T, PA11 / 9T, PA11 / 10T, PA11 / 12T, PA12 / 9T, PA12 / 10T and PA12 / 12T or PA11 / MXD6, PA11 / MXD10, PA12 / MXD6, PA12 / MXD10, etc.

[0236] In a fourth variant, said layer (2') consists of a composition mainly comprising at least one polyolefin.

[0237] Impact modifiers and polyolefins The impact modifier advantageously consists of a polymer, in particular a polyolefin, having a flexural modulus, measured according to standard ISO 178:2010, determined at 23°C and 50% relative humidity: RH, of less than 100 MPa and a Tg (measured according to standard 11357-2:2013 at the inflection point of the DSC thermogram, with a heating rate of 20 K / min) of less than 0°C.

[0238] The polyolefins of the impact modifier may be functionalized or unfunctionalized, or may be a mixture of at least one functionalized and / or at least one unfunctionalized. For simplicity, the polyolefins are designated (B) and functionalized polyolefins (B1) and unfunctionalized polyolefins (B2) are described below.

[0239] The non-functionalized polyolefins (B2) are conventionally homopolymers or copolymers of alpha-olefins or diolefins, such as ethylene, propylene, 1-butene, 1-octene or butadiene. Examples that may be mentioned include: - polyethylene homopolymers and copolymers, in particular LDPE, HDPE, LLDPE (linear low density polyethylene), VLDPE (very low density polyethylene) and metallocene polyethylene; propylene homopolymers or copolymers, - Ethylene / alpha-olefins such as ethylene / propylene, EPR (short for ethylene-propylene-rubber) and ethylene / propylene / diene (EPDM) copolymers. - styrene / ethylene-butene / styrene (SEBS), styrene / butadiene / styrene (SBS), styrene / isoprene / styrene (SIS) and styrene / ethylene-propylene / styrene (SEPS) block copolymers. - copolymers of ethylene with at least one product selected from salts or esters of unsaturated carboxylic acids, such as alkyl (meth)acrylates (for example methyl acrylate), or vinyl esters of saturated carboxylic acids, such as vinyl acetate (EVA), the proportion of comonomer can be up to 40% (by weight);

[0240] The functionalized polyolefins (B1) may be polymers of α-olefins carrying reactive units (functional groups). Such reactive units are acid, anhydride or epoxy functional groups. By way of example, mention may be made of the aforementioned polyolefins (B2) grafted or copolymerized or terpolymerized with unsaturated epoxides such as glycidyl (meth)acrylate, or with carboxylic acids or the corresponding salts or esters such as (meth)acrylic acid, the latter being possible to fully or partially neutralize with metals such as Zn, or with carboxylic anhydrides such as maleic anhydride. The functionalized polyolefins are, for example, PE / EPR mixtures, the weight ratio of which may vary within a wide range, for example between 40 / 60 and 90 / 10, said mixtures being cografted with anhydrides, especially maleic anhydride, for example with a degree of grafting of 0.01% to 5% (by weight).

[0241] The functionalized polyolefin (B1) may be chosen from the following (co)polymers grafted with maleic anhydride or with glycidyl methacrylate, the degree of grafting being, for example, between 0.01% and 5% (by weight): - PE, PP, copolymers of ethylene with propylene, butene, hexene or octene, containing, for example, 35% to 80% (by weight) of ethylene; - Ethylene / alpha-olefins such as ethylene / propylene, EPR (short for ethylene-propylene-rubber) and ethylene / propylene / diene (EPDM) copolymers. - styrene / ethylene-butene / styrene (SEBS), styrene / butadiene / styrene (SBS), styrene / isoprene / styrene (SIS) and styrene / ethylene-propylene / styrene (SEPS) block copolymers. - copolymers of ethylene and vinyl acetate (EVA) containing up to 40% (by weight) of vinyl acetate; - copolymers of ethylene and alkyl (meth)acrylates containing up to 40% (by weight) of alkyl (meth)acrylate; - Copolymers of ethylene, vinyl acetate (EVA) and alkyl (meth)acrylates containing up to 40% (by weight) of comonomer.

[0242] The functionalized polyolefin (B1) may also be selected from ethylene / propylene copolymers, in which propylene predominates, grafted with maleic anhydride and then condensed with a monoaminated polyamide (or polyamide oligomer) (products described in EP-A-0342066).

[0243] The functionalized polyolefin (B1) may also be a copolymer or terpolymer of at least the following units: (1) ethylene, (2) an alkyl (meth)acrylate or a saturated carboxylic acid vinyl ester, and (3) an anhydride, such as maleic or (meth)acrylic anhydride, or an epoxy, such as glycidyl (meth)acrylate.

[0244] As examples of the latter type of functionalized polyolefins, the following copolymers may be mentioned, in which ethylene preferably represents at least 60% (by weight) and the termonomers (functional groups) represent, for example, 0.1% to 10% (by weight) of the copolymer: - ethylene / alkyl (meth)acrylate / (meth)acrylic acid or maleic anhydride or glycidyl methacrylate copolymers; -ethylene / vinyl acetate / maleic anhydride or glycidyl methacrylate copolymers; - Ethylene / vinyl acetate or alkyl (meth)acrylate / (meth)acrylic acid or maleic anhydride or glycidyl methacrylate copolymers.

[0245] In the aforementioned copolymers, the (meth)acrylic acid can be salified with Zn or Li.

[0246] The term "alkyl (meth)acrylate" in (B1) or (B2) denotes C1-C8 alkyl methacrylates and acrylates, and may be selected from methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, methyl methacrylate and ethyl methacrylate.

[0247] Furthermore, the polyolefins (B1) may also be crosslinked via any suitable process or agent (diepoxy, diacid, peroxide, etc.) The term "functionalized polyolefins" also includes mixtures of the above-mentioned polyolefins with difunctional agents such as diacids, dianhydrides, diepoxy, etc. that can react with these polyolefins, or mixtures of at least two functionalized polyolefins that can react together.

[0248] The above-mentioned copolymers (B1) and (B2) can be copolymerized in a random or block manner and can have a linear or branched structure.

[0249] The molecular weight, MFI index and density of these polyolefins can also vary within wide limits that will be appreciated by those skilled in the art. MFI is the abbreviation for Melt Flow Index. It is measured according to standard ASTM 1238.

[0250] The non-functionalized polyolefin (B2) is advantageously chosen from polypropylene homopolymers or copolymers and any ethylene homopolymer or copolymer of ethylene with a comonomer of higher α-olefin type, such as butene, hexene, octene or 4-methyl-1-pentene. Mention may be made, for example, of PP, high density PE, medium density PE, linear low density PE, low density PE or very low density PE. These polyethylenes are known to those skilled in the art to be produced according to the "free radical" process, according to "Ziegler" type catalysis or, more recently, according to "metallocene" catalysis.

[0251] The functionalized polyolefin (B1) is advantageously selected from any polymer that comprises α-olefin units and units with polar reactive functional groups, such as epoxy, carboxylic acid or carboxylic anhydride functional groups. Examples of such polymers that may be mentioned include terpolymers of ethylene, alkyl acrylate and maleic anhydride or glycidyl methacrylate, such as the Lotader® products from the applicant, or polyolefins grafted with maleic anhydride, such as the Orevac® products from the applicant, as well as terpolymers of ethylene, alkyl acrylate and (meth)acrylic acid. Mention may also be made of polypropylene homopolymers or copolymers grafted with carboxylic anhydrides and then condensed with polyamides or monoaminated oligomers of polyamides.

[0252] Additives The additives optionally used in the composition of the invention are conventional additives used in polyamides and are well known to those skilled in the art and are described, inter alia, in EP 2098580.

[0253] For example, they may be selected from catalysts, antioxidants, heat stabilizers, UV absorbers, light stabilizers, lubricants, inorganic fillers, flame retardants, nucleating agents, colorants, reinforcing fibers, waxes and mixtures thereof.

[0254] The term "catalyst" refers to a polycondensation catalyst such as a mineral or organic acid.

[0255] Advantageously, the proportion by weight of catalyst is between about 50 ppm and about 5000 ppm, and in particular between about 100 and about 3000 ppm, relative to the total weight of the composition.

[0256] Advantageously, the catalyst is chosen from phosphoric acid (H3PO4), phosphorous acid (H3PO3) and hypophosphorous acid (H3PO2), or mixtures thereof.

[0257] By way of example, the stabilizer may be a UV stabilizer, an organic stabilizer, or more generally a combination of organic stabilizers, such as phenolic antioxidants (e.g., types such as Irganox® 245 or 1098 or 1010 from Ciba-BASF), phosphite antioxidants (e.g., Irgafos® 126 and Irgafos® 168 from Ciba-BASF), and possibly other stabilizers, such as HALS (Hindered-Amine Light Stabilizers) (e.g., Tinuvin® 770 from Ciba-BASF), UV absorbers (e.g., Tinuvin® 312 from Ciba) or phosphorus stabilizers. Amine-type antioxidants, such as Naugard® 445 from Crompton, or multifunctional stabilizers, such as Nylostab® S-EED from Clariant, may also be used.

[0258] The stabilizer may also be a mineral stabilizer, such as a copper-based stabilizer. Examples of such mineral stabilizers that may be mentioned include copper acetate and halides. It should be noted that other metals, such as silver, may also be considered, but said metals are known to be less effective. These copper-based compounds are typically combined with alkali metal halides, particularly potassium halides.

[0259] About plasticizers By way of example, the plasticizer may be selected from benzenesulfonamide derivatives, such as n-butylbenzenesulfonamide (BBSA); ethyltoluenesulfonamide or N-cyclohexyltoluenesulfonamide; hydroxybenzoic acid esters such as 2-ethylhexyl parahydroxybenzoate, 2-decylhexyl parahydroxybenzoate; tetrahydrofurfuryl alcohol esters or ethers, such as oligoethyleneoxytetrahydrofurfuryl alcohol; and esters of citric acid or hydroxymalonic acid, such as oligoethyleneoxymalonate.

[0260] It would not be outside the scope of the invention to use a mixture of plasticizers.

[0261] The additives, if present in the composition, are advantageously present in an amount of from 1% to 20% by weight, especially from 5% to 15% by weight, in particular from 5% to 12% by weight.

[0262] About antistatic fillers Antistatic fillers are, for example, selected from carbon black, graphite, carbon fibers and carbon nanotubes, in particular carbon black and carbon nanotubes.

[0263] About the structure All of the embodiments of layer (1) described above in the section "Regarding Layer (1)" may be used in the structures detailed in this section.

[0264] In one embodiment, the layer (1) is located between layer (2) and layer (2').

[0265] Advantageously, said layer (2') is the layer in contact with the transport fluid.

[0266] Preferably, said layer (2') is as defined for layer (2), and preferably layers (2) and (2') are identical.

[0267] In one embodiment, layers (2) and (2') may be different and only layer 2' may contain antistatic charges.

[0268] In the latter embodiment, the fact that said layer (2') is as defined for layer (2) means that the compositions of layer (2) and layer (2') may be the same or different.

[0269] If they are different, they may differ with respect to the polyamide or the proportion of polyamide, or with respect to one of the other components of the composition.

[0270] Advantageously, the composition of layer (2) comprises PA11, PA12 or PA612, and the recycled material is obtained from monolayer tubes and / or tanks consisting of a composition comprising only PA11. In particular, the composition of layer (1) consists of at most 99.8% recycled material.

[0271] Advantageously, the composition of layer (2) comprises PA11, PA12 or PA612 and the recycled material is obtained from a monolayer tube and / or tank containing a composition comprising only PA11. In particular, the composition of layer (1) consists of at most 99.8% recycled material and the composition of layer (2') comprises PA11, PA12 or PA612.

[0272] Advantageously, the composition of layer (2) comprises PA11, PA12 or PA612 and 3% to 45% (by weight) of at least one impact modifier, in particular 5% to 20% (by weight) of at least one impact modifier, the recycled material being obtained from monolayer tubes and / or tanks containing a composition comprising only PA11. In particular, the composition of layer (1) consists of at most 99.8% recycled material.

[0273] Advantageously, the composition of layer (2) comprises PA11, PA12 or PA612 and 3% to 45% (by weight) of at least one impact modifier, in particular 5% to 20% (by weight) of at least one impact modifier, and the recycled material is obtained from a monolayer tube and / or tank consisting of a composition comprising only PA11. In particular, the composition of layer (1) consists of at most 99.8% recycled material and the composition of layer (2') comprises PA11, PA12 or PA612 and 3% to 45% (by weight) of at least one impact modifier, in particular 5% to 20% (by weight) of at least one impact modifier.

[0274] Advantageously, the composition of layer (2) and layer (2') is the same, and therefore layers (2) and (2') are identical, i.e. both the polyamide and the other constituents of the composition are the same in nature and proportion, and the thickness of both layers (2) and (2') is the same. Layer (2') is therefore layer (2).

[0275] In the first variant of the multi-layer tubular structure (MLT), it consists of three layers (2) / / (1) / / (2').

[0276] Advantageously, it consists of three layers (2) / / (1) / / (2).

[0277] In one embodiment, at least one binder layer (3) is present, said layer (3) being located between layer (2) and layer (1) and / or between layer (1) and layer (2').

[0278] In the second variant of the multi-layer tubular structure (MLT), it consists of four layers (2) / / binder (3) / / (1) / / (2'), in particular (2) / / binder (3) / / (1) / / (2).

[0279] In the third variant of the multilayer tubular structure (MLT), it consists of four layers (2) / / (1) / / binder (3) / / (2'), in particular (2) / / (1) / / binder (3) / / (2).

[0280] In the fourth variant of the multilayer tubular structure (MLT), it consists of five layers (2) / / binder (3) / / (1) / / binder (3) / / (2'), in particular (2) / / binder (3) / / (1) / / binder (3) / / (2).

[0281] In this fourth variant, the two binder layers (3) may be identical or different; in particular, they are identical.

[0282] In another embodiment, at least one EVOH layer is present, said layer (3) being located between layer (1) and layer (2').

[0283] Thus, the multi-layer tubular structure (MLT) consists of four layers (2) / / (1) / / EVOH / / (2'), specifically (2) / / (1) / / EVOH / / (2).

[0284] In one embodiment, said layer (1) occupies at least 10%, in particular at least 30%, especially at least 50% of the total thickness of said multi-layer tubular structure (MLT).

[0285] Advantageously, said layer (1) occupies at least 60%, in particular at least 70%, of the total thickness of said multi-layer tubular structure (MLT).

[0286] In one embodiment of one of the four variants of the multilayer tubular structure (MLT) or four-layer structure comprising EVOH, the composition of layer (1) does not comprise polyamides denoted A and B, and the composition of layer (2) comprises a polyamide selected from those denoted E, F and mixtures thereof.

[0287] In another embodiment of one of the four variants of the multi-layer tubular structure (MLT) or four-layer structure comprising EVOH, the composition of layer (1) comprises a polyamide selected from those denoted A, B and mixtures thereof, and the composition of layer (2) does not comprise the polyamides denoted E and F.

[0288] In yet another embodiment of one of the four variants of the multi-layer tubular structure (MLT) or four-layer structure comprising EVOH, the composition of the layer (1) comprises a polyamide selected from those denoted A, B and mixtures thereof, and the composition of the layer (2) comprises a polyamide selected from those denoted E, F and mixtures thereof.

[0289] In yet another embodiment of one of the four variants of the multilayer tubular structure (MLT) or four-layer structure comprising EVOH, the composition of layer (1) does not comprise polyamides designated A and B, and the composition of layer (2) does not comprise polyamides designated E and F.

[0290] Advantageously, in these last four embodiments, layer (1) is obtained from a single-layer recycle tube or a single-layer recycle tank or a mixture of the two.

[0291] Advantageously, in these last four embodiments, layer (1) is obtained from a single-layer recycled tube or a single-layer recycled tank or a mixture of the two, and only said composition of said layer (1) comprises at least one impact modifier.

[0292] Advantageously, in these last four embodiments, layer (1) is obtained from a monolayer recycle tube or a monolayer recycle tank or a mixture of these two with said composition of said layer (1), and said compositions of layers (2) and (2') also comprise at least one impact modifier.

[0293] Advantageously, in these last four embodiments, layer (1) is obtained from a multi-layer recycle tube or a multi-layer recycle tank or a mixture of the two.

[0294] Advantageously, in these last four embodiments, layer (1) is obtained from a multi-layer recycled tube or a multi-layer recycled tank or a mixture of the two, and only said composition of said layer (1) comprises at least one impact modifier.

[0295] Advantageously, in these last four embodiments, layer (1) is obtained from a single-layer recycle tube or a multi-layer recycle tank or a mixture of the two.

[0296] Advantageously, in these last four embodiments, layer (1) is obtained from a multi-layer recycle tube or a single-layer recycle tank or a mixture of the two.

[0297] Advantageously, in these last four embodiments, layer (1) is obtained from a multilayer recycled tube, and said composition of layer (1), as well as said compositions of layers (2) and (2'), comprise at least one impact modifier.

[0298] In one embodiment, the multi-layer tubular structure (MLT) is intended to transport a fluid selected from fuels such as gasoline, in particular alcohol blended gasoline, biogasoline or diesel, in particular biodiesel.

[0299] About binders Binders are described inter alia in patents EP 1 452 307 and EP 1 162 061, EP 1 216 826, EP 0 428 833 and EP 3 299 165.

[0300] It is implicit that layers (2) and (1) or (1) and (2') adhere to one another. The binder layer is intended to be interposed between two layers that do not adhere to one another or that are difficult to adhere to one another.

[0301] Binders include, for example, compositions based on 50% copolyamide 6 / 12 (70 / 30 by weight) with Mn 16 000 and 50% copolyamide 6 / 12 (30 / 70 by weight) with Mn 16 000, compositions based on PP (polypropylene) grafted with maleic anhydride (known under the name Admer QF551A from the company Mitsui), compositions based on PA610 (Mn 30 000, defined elsewhere) and 36% PA6 (Mn 28 000) and 1.2% organic stabilizer (consisting of 0.8% phenol Lowinox 44B25 from Great Lakes, 0.2% phosphite Irgafos 168 from Ciba and 0.2% UV stabilizer Tinuvin 312 from Ciba), compositions based on PA612 (Mn 29 000, defined elsewhere) and 36% PA6 (Mn 28 a composition based on PA610 (Mn 30 000, as defined elsewhere) and 36% PA12 (Mn 35 000, as defined elsewhere) and 1.2% organic stabilizer (consisting of 0.8% phenolic Lowinox 44B25 from Great Lakes, 0.2% phosphite Irgafos 168 from Ciba and 0.2% UV stabilizer Tinuvin 312 from Ciba); a composition based on PA610 (Mn 30 000, as defined elsewhere) and 36% PA12 (Mn 35 000, as defined elsewhere) and 1.2% organic stabilizer (consisting of 0.8% phenolic Lowinox 44B25 from Great Lakes, 0.2% phosphite Irgafos 168 from Ciba and 0.2% UV stabilizer Tinuvin 312 from Ciba); A composition based on Exxelor VA1801 (Exxon) and 1.2% organic stabilizer (consisting of 0.8% phenolic Lowinox 44B25 from Great Lakes, 0.2% phosphite Irgafos 168 from Ciba and 1.2% UV-resistant Tinuvin 312 from Ciba) or a composition based on 40% PA6.10 (Mn 30,000, as defined elsewhere), 40% PA6 (Mn 28,000, as defined elsewhere) and 20% ethylene / ethyl acrylate / anhydride impact modifier in a mass ratio of 68.5 / 30 / 1.5 (MFI 6, 190°C, less than 2.16 kg), and 1.2% organic stabilizer (0.The composition may be, but is not limited to, a composition based on 8% phenol Lowinox 44B25, 0.2% phosphite Irgafos 168 from Ciba, and 0.2% UV stabilizer Tinuvin 312 from Ciba.

[0302] According to another aspect, the invention relates to a method for preparing a tubular structure as defined above, characterized in that it comprises the extrusion, in an extruder, optionally equipped with a degassing zone, of at least one layer (1) consisting of at least 50% recycled material as defined above, after recovery of used pipes from motor vehicles.

[0303] All of the embodiments of layer (1) described above in the section "Regarding Layer (1)" may be used in the process detailed in this section.

[0304] In one embodiment, the used pipes are collected and then crushed into granules.

[0305] In another embodiment, the fluid residue has been fully or partially extracted from the used pipe before or after comminution.

[0306] In yet another embodiment, the extraction is performed by washing or ventilation.

[0307] Advantageously, washing is carried out using a solvent, in particular methanol.

[0308] Advantageously, the ventilation is performed by means of an inerting oven.

[0309] In one embodiment, extraction is performed by a degassing zone in said extruder after comminution.

[0310] Advantageously, the spent pipe is cleaned before or after grinding to remove any residual oligomers that may be present in the spent pipe.

[0311] In one embodiment, the method comprises the steps of: 1) recovering used single and / or multi-layer tubes and / or used tanks from a motor vehicle; 2) optionally cleaning any oligomers present; 3) optionally extracting the fluid residue; 4) crushing the tube and / or the tank; 5) extracting the fluid residue if not done in step 3); 6) extruding the comminuted tubes and / or tanks into a single or multi-layer tubular structure.

[0312] According to another aspect, the disclosure relates to the use of used mono- and / or multi-layer tubes and / or tanks initially transporting or containing a motor vehicle fluid as defined above, in particular air, oil, water, a urea solution, a glycol-based coolant, or a fuel, such as gasoline, in particular alcohol-blended gasoline, biogasoline or diesel, in particular biodiesel, or hydrogen, for the preparation of a mono- and / or multi-layer tubular structure intended for transporting the motor vehicle fluid, in particular air, oil, water, a urea solution, a glycol-based coolant, or a fuel, such as gasoline, in particular alcohol-blended gasoline, biogasoline or diesel, in particular biodiesel, or hydrogen, wherein said used mono- and / or multi-layer tubes and / or said used tanks have been crushed into granules, and the fluid residues present in said tubes and / or tanks have been fully or partially extracted before or after crushing of said tubes and / or tanks, and wherein said tubular structure has a viscosity of less than 0.3 g / m during the first storage of gasoline, in particular alcohol-blended gasoline. 2 The present invention relates to a method for treating a pulmonary circulation, the method comprising the steps of:

[0313] All of the embodiments of layer (1) described above in the section "Regarding Layer (1)" may be used for the applications detailed in this section.

[0314] Advantageously, said used single layer and / or multi-layer tubes and / or said used tanks are crushed into granules, excluding reconstitution with or without subsequent reformulation after crushing. [Brief description of the drawings]

[0315] [Figure 1] Fourier transform infrared (FTIR) analysis in attenuated total reflectance (ATR) mode of a milled VHU PA 11 PL gasoline line (continuous grey line) compared to a PA 11 PL gasoline line based 100% on virgin material (continuous black line). [Diagram 2] 1 shows the CH2CO areas of various secondary amide, primary amide and carboxylic acid functional groups in 13C NMR in solvent mixtures with a HFIP / CD2Cl2 ratio of 1 / 3.

[0316] Top spectrum; PA 11 PL milled ELV petrol line and bottom spectrum: PA 11 PL petrol line based on 100% virgin material. EXAMPLES

[0317] Compositions of the Invention The monolayer tube of the present invention: The tube size is 8 x 1 mm.

[0318] Preparation of single layer constructs (tubes): The monolayer structures are produced by extrusion. A Maillefer industrial extrusion line is used.

[0319] The line includes a single screw extruder with a screw profile suitable for polyamide. In addition, the extrusion line includes: a die punch assembly disposed at the end of the extrusion head; the inside diameter of the die and the outside diameter of the punch being selected as a function of the structure to be made and the material from which it is constructed, as well as the size of the tube and the line speed; a vacuum tank with an adjustable level of vacuum, in which water, generally maintained at 20 ° C, circulates, in whose facade gauges are inserted for adapting the tube to its final dimensions. The diameter of the gauges depends on the dimensions of the tube to be produced (typically 8.1-10 mm for a tube with an outside diameter of 8 mm and a thickness of 1 mm); a cooling tank in which water is maintained at about 20°C to cool the tubes along their path from the head to the drawing bench; Diameter measuring part; Suitable for drawing benches.

[0320] Prior to testing, to ensure the best properties of the tube and good extrusion quality, the extruded material is verified to have a pre-extrusion residual moisture content of less than 0.08%. If this is not the case, an additional step is performed to dry the material before testing, typically in a vacuum dryer at 80°C overnight.

[0321] Tubes meeting the characteristics described in this patent application are harvested after stabilization of the extrusion parameters and the target dimensions of the tube no longer change over time. The diameter is monitored by a laser diameter gauge installed at the end of the line.

[0322] The line speed is typically 20 m / min. It generally varies between 5 and 100 m / min.

[0323] The speed of the extruder screw depends on the thickness and diameter of the tube, as known to those skilled in the art.

[0324] In general, the temperatures of the extruder and tools (heads and joints) should be set sufficiently higher than the melting points of the compositions under consideration so that they remain molten, thus preventing them from solidifying and blocking the machine.

[0325] The monolayer tubes produced by the above extrusion were then evaluated on several criteria: Ageing: this is the durability; in other words it indicates the resistance of the tube to oxidative ageing in hot air. The tubes are aged in air at 150°C and then shocked according to standard DIN 73378 manufactured at -40°C. The half-life (in hours) is indicated, which corresponds to the time until 50% of the tested tubes break. A qualitative commentary accompanies this value.

[0326] A "++" rating is given for durability, which can be described as "very good", corresponding to a half-life of 200 hours or more.

[0327] A "+" rating is given for durability (resistance to thermo-oxidative aging) which can be described as "good", corresponding to a half-life of 100 hours or more (and less than 200 hours).

[0328] A "+-" rating is given for durability (resistance to thermo-oxidative aging) which can be described as "acceptable", corresponding to a half-life of 50 hours or more (and less than 100 hours).

[0329] A "-" rating is given for durability (resistance to thermo-oxidative aging) which can be described as "poor", corresponding to less than 50 hours.

[0330] If a half-life figure is given to indicate nuance, this figure is rounded to 25 hours, taking into account significant figures related to the accuracy of the assessment.

[0331] Ready-to-use: Geometry, mechanical behavior and contamination properties suitable for installation in new vehicles.

[0332] +: Can be used as is.

[0333] +: Cannot be used as is.

[0334] Oligomers (insoluble extractables): This test consists of filling a tube with FAM B-type alcohol blend gasoline at 60°C for 96 hours, then emptying it and filtering it into a beaker. The filter and residue are 0.3 g / m 2 It is dried until a constant mass is obtained, which must be less than or equal to (the inner surface area of ​​the tube). [Table 1] TIFF2024526563000001.tif236170

[0335] The following compositions were compounded in a Coperion / Werner 40 mm twin screw extruder at 70 kgh, 300 rpm, set point of 270° C., degassing at −100 mm Hg.

[0336] "PA11PL" is virgin PA11 containing 7% BBSA and 1% stabilizers.

[0337] "PA11NX2" is virgin PA11 containing 10% PA610, 5% maleic anhydride functionalized EPR impact modifier and 1% stabilizer.

[0338] "PA12PL" is virgin PA12 containing 7% BBSA and 1% stabilizers.

[0339] "PA11 / 10TPL" is virgin PA 11 / 10T (0.7 / 0.3) containing 7% BBSA and 1% stabilizer.

[0340] "PA610PL" is virgin PA610 containing 7% BBSA and 1% stabilizers.

[0341] "PA612PL" is virgin PA612 containing 7% BBSA and 1% stabilizers.

[0342] The following composition is ground material from tubes and tanks recovered from an ELV in a scrap yard.

[0343] "Ground ELV PA 11 PL Gasoline Line" is a gasoline line chip recovered from an ELV having a molar ratio of primary amide functional groups to secondary amide functional groups of 0.02, a molar ratio of nitrile functional groups of 0.05, and a molar ratio of methyl functional groups of 0.004.

[0344] "Ground ELV PA 12 PL Gasoline Line" is a gasoline line chip recovered from an ELV having a molar ratio of primary amide functional groups to secondary amide functional groups of 0.02, a molar ratio of nitrile functional groups of 0.05, and a molar ratio of methyl functional groups of 0.004.

[0345] "Crushed ELV PA11 PL Tank" is a gasoline tank chip recovered from ELV having a molar ratio of primary amide functional groups to secondary amide functional groups of 0.01, a molar ratio of nitrile functional groups of 0.02, and a molar ratio of methyl functional groups of 0.002.

[0346] "Ground ELV PA12 PL Tank" is a gasoline tank chip recovered from ELV having a molar ratio of primary amide functional groups to secondary amide functional groups of 0.01, a molar ratio of nitrile functional groups of 0.02, and a molar ratio of methyl functional groups of 0.002.

[0347] "Ground ELV PA11 PL Pneumatic Transport Line" is brake pipe chips recovered from ELV having a molar ratio of primary amide functional groups to secondary amide functional groups of 0.04, a molar ratio of nitrile functional groups of 0.1, and a molar ratio of methyl functional groups of 0.01.

[0348] "Ground ELV PA12PL Pneumatic Transport Line" is brake pipe chips recovered from ELV having a molar ratio of primary amide functional groups to secondary amide functional groups of 0.03, a molar ratio of nitrile functional groups of 0.09, and a molar ratio of methyl functional groups of 0.008.

[0349] "Ground ELV PA610PL Pneumatic Conveying Line" is recovered brake pipe chips from ELV having a molar ratio of primary amide functional groups to secondary amide functional groups of 0.02, a molar ratio of nitrile functional groups of 0.07, and a molar ratio of methyl functional groups of 0.010.

[0350] "Ground ELV PA612PL Pneumatic Conveying Line" is recovered brake pipe chips from ELV having a molar ratio of primary amide functional groups to secondary amide functional groups of 0.03, a molar ratio of nitrile functional groups of 0.08, and a molar ratio of methyl functional groups of 0.009.

[0351] "Ground ELV PA610PL gasoline line" is a gasoline line chip recovered from ELV having a molar ratio of primary amide functional groups to secondary amide functional groups of 0.01, a molar ratio of nitrile functional groups of 0.03, and a molar ratio of methyl functional groups of 0.001.

[0352] "Ground ELV PA612PL gasoline line" is a gasoline line chip recovered from ELV having a molar ratio of primary amide functional groups to secondary amide functional groups of 0.01, a molar ratio of nitrile functional groups of 0.04, and a molar ratio of methyl functional groups of 0.002.

[0353] "Ground ELV PA610 PL Tank" is a gasoline tank chip recovered from ELV having a molar ratio of primary amide functional groups to secondary amide functional groups of 0.009, a molar ratio of nitrile functional groups of 0.01, and a molar ratio of methyl functional groups of 0.001.

[0354] "Ground ELV PA612 PL Tank" is a gasoline tank chip recovered from ELV having a molar ratio of primary amide functional groups to secondary amide functional groups of 0.008, a molar ratio of nitrile functional groups of 0.02, and a molar ratio of methyl functional groups of 0.001.

[0355] The molar ratio is determined as defined in the text above.

[0356] The multi-layer tube of the present invention: The layers are listed from outside to inside, followed by their respective thicknesses as percentages. The size of the tube is 8 x 1 mm.

[0357] Preparation of multi-layered structures (tubes): The multi-layer tubes are produced by co-extrusion using a Maillefer multi-layer extrusion industrial line equipped with five extruders connected to a multi-layer extrusion head with a helical mandrel.

[0358] The screw used is a single extrusion screw with a screw profile adapted to polyamide. In addition to the five extruders and the multi-layer extrusion head, the extrusion line is equipped with: a die punch assembly disposed at the end of the coextrusion head; the inner diameter of the die and the outer diameter of the punch are selected as a function of the structure to be made and the material from which it is constructed, as well as the size of the tube and the line speed; a vacuum tank with an adjustable level of vacuum, in which water, generally maintained at 20°C, circulates and in which gauges for adapting the tube to its final dimensions are immersed. The diameter of the gauges depends on the dimensions of the tube to be produced (typically 8.5-10 mm for a tube with an outer diameter of 8 mm and a thickness of 1 mm); a series of cooling tanks in which water is maintained at about 20°C to cool the tubes along their path from the head to the drawing bench; Diameter measuring part; Suitable for drawing benches.

[0359] A configuration with five extruders is used to make tubes ranging from 2 to 5 layers (and also single layer tubes). For structures with fewer than 5 layers, several extruders are fed with the same material.

[0360] Prior to testing, to ensure the best properties of the tube and good extrusion quality, the extruded material is verified to have a pre-extrusion residual moisture content of less than 0.08%. If this is not the case, an additional step is performed to dry the material before testing, typically in a vacuum dryer at 80°C overnight.

[0361] Tubes meeting the characteristics described in this patent application are harvested after stabilization of the extrusion parameters and the target dimensions of the tube no longer change over time. The diameter is monitored by a laser diameter gauge installed at the end of the line.

[0362] The line speed is typically 20 m / min. It generally varies between 5 and 100 m / min.

[0363] The speed of the extruder screw depends on the layer thickness and the screw diameter, as known to those skilled in the art.

[0364] In general, the temperatures of the extruder and tools (heads and joints) should be set sufficiently higher than the melting points of the compositions under consideration so that they remain molten, thus preventing them from solidifying and blocking the machine.

[0365] The "virgin single-layer gasoline line" is an 8 x 1 mm virgin single-layer gasoline line made of PA11PL.

[0366] The "ELV single-wall gasoline line" is an 8 x 1 mm single-wall gasoline line constructed from PA11 PL salvaged from end-of-life emergency vehicles (ELVs).

[0367] "Virgin 3-ply petrol line" is a 8x1mm virgin 3-ply petrol line, inner>PA11NX2 / / PA610 PL / / PA11NX2<outer, with the following thickness distribution: 15% / 70% / 15%.

[0368] "ELV 3-layer gasoline line" is a 3-layer gasoline line of ELV 8 x 1 mm, inner>PA11NX2 / / PA610 PL / / PA11NX2

Claims

1. A composition comprising: (a) 30% to 99.8% (by weight), particularly 50% to 99.8% (by weight), of recycled material from used single-layer and / or multi-layer tubes and / or tanks that initially transported or contained automotive vehicle fluids, in particular air, oil, water, urea solution, glycol-based coolant, or fuel, such as gasoline, particularly alcohol-blended gasoline, bio-gasoline or diesel, particularly biodiesel, or hydrogen, wherein said tubes and / or said tanks are made of a composition mainly comprising at least one polyamide, wherein said used single-layer and / or multi-layer tubes and / or said used tanks are ground into granules, and the fluid residues present in said tubes and / or tanks are completely or partially extracted before or after grinding of said tubes and / or tanks, recycled material, (b) up to 70%, particularly up to 50%, of semi-crystalline aliphatic polyamide, (c) up to 45% (by weight) of at least one impact modifier, particularly 1% to 45% (by weight) of at least one impact modifier, especially 2% to 45% (by weight) of at least one impact modifier, (d) up to 20% (by weight) of at least one plasticizer, (e) up to 0.2% of additives, wherein the polyamide of said used tubes and / or said used tanks has a molar ratio of functional groups resulting from an oxidation reaction selected from primary amide functional groups, nitriles, terminal methyl groups, alkenes, formamides, imides, carboxylic acids and alcohols and mixtures thereof, to amide functional groups greater than that of the same polyamide constituting unused tubes and / or tanks that have not yet transported or contained automotive vehicle fluids, composition.

2. The composition according to claim 1, characterized in that the molar ratio of the functional groups produced by the oxidation reaction is in the range of 1 / 10000 to 1 / 20.

3. The composition according to claim 1, characterized in that the molar ratio of the imide functional groups is in the range of 1 / 1000 to 1 / 20, especially 1 / 500 to 1 / 20, particularly 1 / 200 to 1 / 50.

4. The composition according to claim 1, characterized in that the molar ratio of the carboxylic acid functional groups is in the range of 1 / 5000 to 1 / 20, especially 1 / 3000 to 1 / 50, very preferably 1 / 500 to 1 / 15.

5. The composition according to claim 1, characterized in that the molar ratio of the alcohol functional group is in the range of 1 / 1000 to 1 / 20, preferably 1 / 1000 to 1 / 25, and very preferably 1 / 200 to 1 / 50.

6. The composition according to claim 1, characterized in that the molar ratio of the primary amide functional group is in the range of 1 / 2000 to 1 / 20, preferably 1 / 1000 to 1 / 100, and very preferably 1 / 1000 to 1 / 500.

7. The composition according to claim 1, characterized in that the molar ratio of the nitrile functional group is in the range of 1 / 1000 to 1 / 20, preferably 1 / 500 to 1 / 15, and very preferably 1 / 100 to 1 / 10.

8. The composition according to claim 1, characterized in that the molar ratio of the terminal methyl functional group is in the range of 1 / 5000 to 1 / 50, preferably 1 / 2000 to 1 / 100, and very preferably 1 / 1000 to 1 / 200.

9. A single - layer or multi - layer tubular structure (MLT) for the purpose of transporting automotive fluids, in particular air, oil, water, urea solution, glycol - based coolant, or fuel, such as gasoline, especially alcohol - blended gasoline, bio - gasoline or diesel, especially biodiesel, or hydrogen, comprising at least one layer (1) made of the composition defined in claim 1.

10. During the initial storage of gasoline, especially alcohol-blended gasoline, a maximum of 0.3 g / m ２ of insoluble extract, preferably a maximum of 0.2 g / m ２ A single-layer or multi-layer tubular structure (MLT) according to claim 9, characterized by having.

11. The single - layer or multi - layer tubular structure (MLT) according to claim 9, characterized in that the extraction of the fluid residue is carried out by washing or ventilation.

12. The single - layer or multi - layer tubular structure (MLT) according to claim 9, characterized in that the structure is multi - layer and comprises at least one layer (2).

13. The layer (2) mainly consists of a composition containing at least one semi - crystalline aliphatic polyamide and optionally at least one impact modifier. When the layer (2) mainly consists of a composition containing at least one semi - crystalline aliphatic polyamide which is PA12 and / or PA610 and / or PA612 and / or PA1010, the composition contains the impact modifier, and the layer (2) consists of at least 90% non - recycled material. The multi - layer tubular structure (MLT) according to claim 12.

14. At least one layer (2') comprising a composition mainly containing at least one semi-crystalline aliphatic polyamide, semi-aromatic polyamide or polyolefin, characterized in that said layer (2') consists of at least 90% non-recycled material, the multilayer tubular structure (MLT) according to claim 12.

15. The multilayer tubular structure (MLT) according to claim 14, characterized in that said layer (2') consists of a composition mainly containing at least one semi-aromatic polyamide.

16. The multilayer tubular structure (MLT) according to claim 14, characterized in that said layer (2') consists of a composition mainly containing at least one polyolefin.

17. The multilayer tubular structure (MLT) according to claim 14, characterized in that said layer (1) is between layer (2) and layer (2').

18. The multilayer tubular structure (MLT) according to claim 14, characterized in that layer (2') is a layer in contact with a fluid.

19. The multilayer tubular structure (MLT) according to claim 14, characterized in that layer (2') is as defined for layer (2), preferably layer (2) and (2') are identical.

20. The multilayer tubular structure (MLT) according to claim 14, characterized in that at least one binder layer (3) is present, and said layer (3) is located between layer (2) and layer (1) and / or between layer (1) and layer (2').

21. The single-layer or multilayer tubular structure (MLT) according to claim 9, characterized in that said layer (1) occupies at least 10%, particularly at least 30%, especially at least 50% of the total thickness of said single-layer or multilayer tubular structure (MLT).

22. Said layer (1) At least 50% (by weight), in particular 50% to 99.8% (by weight), of C Ｃ At least one semi-crystalline aliphatic polyamide represented by C, having an average number of carbon atoms per 6 to 18, preferably 8 to 12, nitrogen atoms represented by C 0 to 25% (by weight) of C Ｂ = C Ｃ -1, preferably C Ｂ = C Ｃ -2, having at least one semi-crystalline aliphatic polyamide represented by B, having an average number of carbon atoms per nitrogen atom represented by 0 to 25% (by weight) of C Ａ =C Ｂ -1, preferably C Ａ =C Ｂ -2, a semi-crystalline aliphatic polyamide represented by A having an average number of carbon atoms per nitrogen atom comprises from 0% to 45% (by weight) of at least one impact modifier, particularly from 3% to 45% (by weight) of at least one impact modifier, from 0% to 20% (by weight) of at least one plasticizer, from 0% to 0.2% (by weight) of at least one additive, and consists of a composition where the sum of the components is equal to 100%, the single-layer or multilayer tubular structure (MLT) according to claim 9.

23. The single-layer or multilayer tubular structure (MLT) according to claim 22, characterized in that the composition of layer (1) does not contain a plasticizer and / or an impact modifier.

24. ​ The single - layer or multi - layer tubular structure (MLT) according to claim 22, characterized in that the composition of layer (1) contains at least one compound selected from plasticizers, impact modifiers, and additives.

25. The single - layer or multi - layer tubular structure (MLT) according to claim 9, characterized in that the fluid transported by the single - layer and / or multi - layer tube or stored in the tank is the same as the single - layer or multi - layer tubular structure (MLT).

26. The single - layer or multi - layer tubular structure (MLT) according to claim 9, characterized in that the fluid transported by the single - layer and / or multi - layer tube or stored in the tank is different from the multi - layer tubular structure (MLT).

27. Layer (2) is At least 50% (by weight), in particular 50% to 99.8% (by weight), especially 50% to 95% (by weight) of C Ｄ at least one semi-crystalline aliphatic polyamide represented by D having an average number of carbon atoms per 6 to 18, preferably 9 to 15 nitrogen atoms represented by 0 to 25% (by weight) of C Ｅ = C Ｄ -1, preferably C Ｅ = C Ｄ at least one semi-crystalline aliphatic polyamide represented by E having an average number of carbon atoms per nitrogen atom represented by -2 0 to 25% (by weight) of C Ｆ =C Ｅ -1, preferably C Ｆ =C Ｅ -2, a semi-crystalline aliphatic polyamide represented by F having an average number of carbon atoms per nitrogen atom represented by composed of a composition containing at least one impact modifier of 3% to 45% (by weight), in particular at least one impact modifier of 5% to 20% (by weight); at least one plasticizer of 0% to 20% (by weight); at least one additive of 0% to 0.2% (by weight); at least one antistatic filler of 0% to 35% (by weight); and the total of the components is equal to 100%, the multi - layer tubular structure (MLT) according to claim 9.

28. The multi - layer tubular structure (MLT) according to claim 27, characterized in that the composition of layer (1) does not contain polyamides represented by A and B, and the composition of layer (2) contains polyamides selected from those represented by E, F, and mixtures thereof.

29. The multi - layer tubular structure (MLT) according to claim 27, characterized in that the composition of layer (1) contains polyamides selected from those represented by A, B, and mixtures thereof, and the composition of layer (2) does not contain polyamides represented by E and F.

30. The single - layer or multi - layer tubular structure (MLT) according to claim 9, characterized in that layer (1) is derived from a recycled single - layer tube.

31. The single - layer or multi - layer tubular structure (MLT) according to claim 9, characterized in that layer (1) is derived from a recycled multi - layer tube.

32. The multi - layer tubular structure (MLT) according to claim 12, characterized in that the MLT consists of three layers having the following structure: (2) / / (1) / / (2).

33. ​ A method for preparing the tubular structure defined in claim 9, comprising extruding the composition defined in claim 1 in an extruder optionally provided with a degassing zone to form layer (1) after recovering the used pipe from an automotive vehicle.

34. The method according to claim 33, characterized in that the used pipe is ground into granules after recovery.

35. The method according to claim 33, characterized in that the fluid residue is extracted from the used pipe before or after grinding.

36. The method according to claim 35, characterized in that the extraction is carried out by washing or ventilation.

37. The method according to claim 36, characterized in that the washing is carried out using a solvent, in particular methanol.

38. The method according to claim 37, characterized in that the ventilation is carried out using an inert oven.

39. The method according to claim 35, characterized in that the extraction is carried out after grinding by the degassing zone in the extruder.

40. The method according to claim 35, characterized in that the used pipe before or after grinding is cleaned to remove any oligomers present in the used pipe.

41. Use of a used single - layer and / or multi - layer tube and / or tank that first transported or contained a motor vehicle fluid as defined in claim 1 for the preparation of a single - layer tubular structure for the purpose of transporting a motor vehicle fluid as defined in claim 1, in particular air, oil, water, urea solution, glycol - based coolant, or fuel, such as gasoline, in particular alcohol - blended gasoline, bio - gasoline or diesel, in particular biodiesel, or hydrogen, wherein the used single - layer and / or multi - layer tube and / or the used tank are ground into granules, and the fluid residues present in the tube and / or tank are completely or partially extracted before or after grinding of the tube and / or tank, and the tubular structure has less than 0.3 g / m ２ of insoluble extract during the first storage of gasoline, in particular alcohol - blended gasoline.

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