Multilayer structures based on recycled polyamide

Abstract

The present invention relates to a multilayer tubular structure (MLT) for conveying fluids for motor vehicles, the structure comprising at least three layers: at least one layer (1) comprising a composition mainly comprising at least one semi-crystalline aliphatic polyamide, the composition comprising at least 50% recycled material derived from a multilayer tube that has been used to convey fluids for motor vehicles, the tube comprising a composition mainly comprising at least one polyamide; at least one layer (2) comprising a composition mainly comprising at least one semi-crystalline aliphatic polyamide and optionally at least one impact modifier, and when layer (2) comprises a composition mainly comprising at least one semi-crystalline aliphatic polyamide as PA12 and / or PA612 and / or PA1010, the composition comprises the impact modifier; and at least one layer (2') comprising a composition mainly comprising at least one semi-crystalline aliphatic polyamide, the layers (2) and (2') each comprising at least 90% non-recycled material.

Description

[0001] Every year, millions of vehicles are scrapped worldwide. End-of-life vehicles (ELVs) contain many toxic and polluting byproducts (liquid or solid): oil, batteries, air conditioning fluids, and explosive features from airbags, among others. If improperly disposed of, this waste can lead to soil and water pollution and accidents. ELVs are therefore considered hazardous waste.

[0002] A large number of vehicle components can be collected and recycled as used parts or raw materials. Components intended for reuse (headlights, turn signals, engines, radiators, starters, hoods, fenders, doors, etc.) are disassembled and stored for resale.

[0003] Shred the frame and non-renewable components (ferrous and non-ferrous metals, plastics, glass, rubber, etc.) for recycling or landfill.

[0004] The European Guideline 2000 / 53 / EC on end-of-life vehicles has set a 95% recycling and recovery rate for each vehicle's weight from 2015.

[0005] Therefore, only 5% of the final waste (i.e. waste that cannot be handled under current technological and economic conditions and will be incinerated or discharged into a specific storage center) should remain.

[0006] 95% of the recycled and collected materials are processed for:

[0007] Energy harvesting: using waste (oil, tires, plastics, etc.) as a means of generating energy, which is carried out by direct incineration with or without other waste;

[0008] Material collection: Reuse: Reusing unconverted parts that retain their same purpose, or Regeneration: Operations that introduce materials from waste into the production cycle as a whole or part replacement for virgin materials.

[0009] Motor vehicles contain a large number of pipes, especially pipes for conveying fluids such as air, oil (e.g., for cooling transmission oil coolers), water, urea solutions, glycol coolants, fuels such as gasoline (especially biogasoline) or diesel (especially biodiesel) or hydrogen.

[0010] These pipes can be single-layer and / or multi-layer tubular structures, particularly single-layer and / or multi-layer tubular structures based on polyamide.

[0011] When a vehicle reaches the end of its lifespan, the various pipes within it are usually so degraded or excessively degraded that they cannot be reused in their original form without risk or excessive deterioration.

[0012] In fact, pipes, especially those under the hood, are placed in a harsh, oxidizing environment due to the heat generated by the engine (typically reaching 150°C) and the presence of air and therefore oxygen. Every 10°C increase in temperature typically halve the lifespan of the pipe and causes degradation of certain additives in the pipe, such as stabilizers.

[0013] Furthermore, fuel delivery hoses containing plasticizers (such as polyamide hoses) lose most of their plasticizers by the end of their lifespan, and the initially present polyamide has depolymerized and / or degraded and lost most of its stabilizers, which hinders their safe reuse.

[0014] To date, end-of-life vehicle pipelines have not been reused and are usually incinerated, but this contributes to global warming, and the reduction of global warming has become one of the major problems of the 21st century.

[0015] In addition, some motor vehicle manufacturers have the following long-term goal: to make 100% recycled vehicles to achieve zero environmental impact.

[0016] Therefore, providing these manufacturers with recycled pipes becomes crucial and enables a reduction in the amount of pipes that will be discarded or incinerated.

[0017] Therefore, the present invention relates to multilayer tubular structures (MLTs) for conveying fluids for motor vehicles, particularly air, oil (e.g., for cooling transmission oil coolers or TOC), water, urea solutions, glycol coolants, or fuels, such as gasoline (particularly alcohol-based gasoline, biogasoline) or diesel (particularly biodiesel) or hydrogen, said multilayer tubular structure comprising at least three layers as follows:

[0018] At least one layer (1) comprising a composition mainly comprising at least 50% polyamide resin, said polyamide resin comprising at least one first polyamide resin mainly comprising aliphatic units and at least one second resin mainly comprising aromatic units.

[0019] The composition comprises at least 50% recycled material derived from multilayer pipes that have been used to transport fluids for motor vehicles (particularly as defined above), the pipes comprising a composition primarily consisting of at least one polyamide.

[0020] At least one layer (2) comprising a composition mainly comprising at least one semi-crystalline aliphatic polyamide and optionally at least one impact modifier, and when layer (2) comprises a composition mainly comprising at least one semi-crystalline aliphatic polyamide as PA12 and / or PA612 and / or PA1010, the composition comprises the impact modifier, and

[0021] At least one layer (2') comprising a composition mainly comprising at least one semicrystalline aliphatic polyamide,

[0022] The layers (2) and (2') contain at least 90% non-recycled materials.

[0023] Therefore, the inventors have unexpectedly discovered that, based on a polyamide resin comprising at least one first polyamide resin mainly comprising aliphatic units and at least one second resin mainly comprising aromatic units and containing at least 50% recycled material (particularly a layer embedded between two polyamide-based layers containing non-recycled material), it is permissible to construct a multilayer tubular structure comprising at least three layers, regardless of the type of fluid initially transported by the recycled multilayer tube constituting the embedded layers. The multilayer tubular structure is capable of transporting fluids for motor vehicles, particularly air, oil, water, urea solutions, glycol-based coolants, or fuels such as gasoline (particularly biogas) or diesel (particularly biodiesel), or hydrogen.

[0024] In other words, the present invention relates to a multilayer tubular structure (MLT) for conveying fluids for motor vehicles, particularly air, oil (e.g., for cooling transmission oil coolers or TOC), water, urea solutions, glycol coolants, or fuels, such as gasoline (particularly alcohol-based gasoline, biogasoline) or diesel (particularly biodiesel), or said multilayer tubular structure comprising at least three layers:

[0025] At least one layer (1) comprising a composition mainly comprising at least 50% polyamide resin, said polyamide resin comprising at least one first polyamide resin mainly comprising aliphatic units and at least one second resin mainly comprising aromatic units.

[0026] The composition comprises at least 50% recycled material from multilayer pipes that have been used to transport fluids for motor vehicles (particularly as defined above), the pipes comprising a composition mainly consisting of at least one polyamide.

[0027] At least one layer (2) comprising a composition mainly comprising at least one semi-crystalline aliphatic polyamide and optionally at least one impact modifier, and when layer (2) comprises a composition mainly comprising at least one semi-crystalline aliphatic polyamide as PA12 and / or PA612 and / or PA1010, the composition comprises the impact modifier, and

[0028] At least one layer (2') comprising a composition mainly comprising at least one semicrystalline aliphatic polyamide,

[0029] The layers (2) and (2') contain at least 90% non-recycled materials.

[0030] Therefore, the recycled material originates from single-layer and / or multi-layer pipes that were originally used to transport fluids for motor vehicles, and these pipes have been used to transport the fluids for at least several months, and in particular several years.

[0031] The initial fluid transport of single-layer and / or multi-layer pipes therefore does not include native (unused) pipes.

[0032] The term "fluid" refers to the gas or liquid used in motor vehicles, particularly air, oil, water, urea solution, glycol coolant, or fuel such as gasoline (especially ethanol gasoline, biogas) or diesel (especially biodiesel) or hydrogen.

[0033] Advantageously, the fluid refers to fuel, particularly gasoline (especially ethanol gasoline, biogas) or diesel (especially biodiesel).

[0034] The term "gasoline" refers to a mixture of hydrocarbons derived from petroleum distillation, to which additives or alcohols such as methanol and ethanol may be added, with alcohols being the main component in some cases.

[0035] "Alcohol-modified gasoline" refers to gasoline to which methanol or ethanol has been added. It also refers to E95 gasoline, which does not contain petroleum distillates.

[0036] The term "polyamide-based" means that at least 50% by weight of polyamide is present in the layer.

[0037] The statement "a composition comprising primarily at least one polyamide..." means that the polyamide comprises at least 50% by weight of the composition.

[0038] In one embodiment, the layer (2) comprises a composition mainly comprising at least one semi-crystalline aliphatic polyamide and at least one impact modifier comprising 3 to 45% by weight relative to the total weight of the composition.

[0039] Regarding layer (1)

[0040] Layer (1) comprises a composition mainly comprising at least 50% polyamide resin, the polyamide resin comprising at least one first polyamide resin mainly comprising aliphatic units and at least one second resin mainly comprising aromatic units.

[0041] The composition contains at least 50% recycled material from multilayer pipes that have been used to transport fluids for motor vehicles.

[0042] The nomenclature used to define polyamides is described in ISO standard 1874-1:2011 “Plastics - Polyamide (PA) Moulding And Extrusion Material - Part 1: Designation” and is well known to those skilled in the art.

[0043] According to the present invention, the term "polyamide" is equivalent to homopolymer or copolymer.

[0044] The term "first polyamide resin mainly comprising aliphatic units" means that the first resin contains at least 50% aliphatic units.

[0045] The term "second polyamide resin mainly comprising aromatic units" means that the first resin contains at least 50% aromatic units.

[0046] In one embodiment, the first polyamide resin, which mainly comprises aliphatic units, is a semi-crystalline polyamide.

[0047] Advantageously, the first polyamide resin, which mainly comprises aliphatic units, is a semi-crystalline aliphatic polyamide.

[0048] In another embodiment, the second resin, which mainly comprises aromatic units, is a semi-crystalline polyamide.

[0049] Advantageously, the first polyamide resin, which mainly comprises aromatic units, is a semi-crystalline semi-aromatic polyamide.

[0050] In another embodiment, the first polyamide resin, which mainly comprises aliphatic units, and the second resin, which mainly comprises aromatic units, are semi-crystalline polyamides.

[0051] Advantageously, the first polyamide resin, which mainly comprises aliphatic units, is a semi-crystalline aliphatic polyamide, and the first polyamide resin, which mainly comprises aromatic units, is a semi-crystalline semi-aromatic polyamide.

[0052] Throughout this specification, the term "semi-crystalline polyamide" as used within the meaning of this invention refers to a polyamide having a melting temperature (Tm) and a melting enthalpy ΔH >25 J / g, particularly >40 J / g, especially >45 J / g, and a glass transition temperature (Tg) determined by DSC according to ISO standards 11357-1:2016 and 11357-2 and 3:2013 at a heating rate of 20 K / min.

[0053] The at least one aliphatic semi-crystalline polyamide is obtained from the condensation of at least one lactam, or the condensation of at least one amino acid, or the condensation of at least one Xa diamine and at least one Yb dicarboxylic acid.

[0054] When the at least one semicrystalline aliphatic polyamide is obtained from the polycondensation of at least one lactam, the at least one lactam may be selected from C6 to C18, preferably C10 to C18, and more preferably C10 to C12 lactams. C6 to C12 lactams are particularly decanolactam, undecyllactam, and lauryllactam.

[0055] When the at least one semicrystalline aliphatic polyamide is derived from the polycondensation of at least one lactam, it may therefore include a single lactam or several lactams.

[0056] Advantageously, the at least one semicrystalline aliphatic polyamide is obtained from the polycondensation of a single lactam, and the lactam is selected from lauryl lactam and undecyl lactam, advantageously lauryl lactam.

[0057] When the at least one semicrystalline aliphatic polyamide is obtained from the polycondensation of at least one amino acid, the at least one amino acid may be selected from C6 to C18, preferably C10 to C18, and more preferably C10 to C12 amino acids.

[0058] C6 to C12 amino acids, particularly 6-aminohexanoic acid, 9-aminononanoic acid, 10-aminodecanoic acid, 10-aminoundecanoic acid, 12-aminododecanoic acid and 11-aminoundecanoic acid and their derivatives, especially N-heptyl-11-aminoundecanoic acid.

[0059] When the at least one semicrystalline aliphatic polyamide is obtained from the polycondensation of at least one amino acid, it may therefore include a single amino acid or several amino acids.

[0060] Advantageously, the semicrystalline aliphatic polyamide is obtained from the polycondensation of a single amino acid, and the amino acid is selected from 11-aminoundecanoic acid and 12-aminododecanoic acid, advantageously 11-aminoundecanoic acid.

[0061] When the at least one semicrystalline aliphatic polyamide is obtained from the polycondensation of at least one C4-C36, preferably C5-C18, preferably C5-C12, more preferably C10-C12 Xa diamine and at least one C4-C36, preferably C6-C18, preferably C6-C12, more preferably C10-C12 Yb diacid, then the at least one Xa diamine is an aliphatic diamine, and the at least one Yb diacid is an aliphatic diacid.

[0062] The diamine may be linear or branched. Advantageously, it is linear.

[0063] The at least one C4-C36 Xa diamine may be particularly selected 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-dodecanediamine, 1,13-tetridemethylenediamine, 1,14-tetradecanemethylenediamine, 1,16-hexadecanemethylenediamine, and 1,18-octadecanemethylenediamine, octadecenediamine, eicosanediamine, docosanediamine, and diamines derived from fatty acids.

[0064] Advantageously, the at least one Xa diamine is C5-C18 and is selected 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-tetridemethylenediamine, 1,14-tetradecamethylenediamine, 1,16-hexadecamethylenediamine, and 1,18-octadecamethylenediamine.

[0065] Advantageously, the at least one C5 to C12 Xa diamine is particularly selected 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.

[0066] Advantageously, the at least one C6 to C12 Xa diamine is particularly selected from 1,6-hexamethylenediamine, 1,7-heptamethylenediamine, 1,8-octamethylenediamine, 1,9-nonamethylenediamine, 1,10-decamethylenediamine, 1,11-undecamethylenediamine and 1,12-dodecimethylenediamine.

[0067] Advantageously, the Xa diamine used is a C10 to C12 diamine, particularly selected from 1,10-decamethylenediamine, 1,11-undecamethylenediamine and 1,12-dodecimethylenediamine.

[0068] The at least one C4 to C36 Yb dicarboxylic acid may be selected from succinic acid, glutaric acid, adipic acid, octanoic acid, azelaic acid, sebacic acid, undecanoic acid, dodecanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecanoic acid, octadecanoic acid, and diacids derived from fatty acids.

[0069] The diacid can be linear or branched. Advantageously, it is linear.

[0070] Advantageously, the at least one Yb dicarboxylic acid is C6 to C18, and is selected from succinic acid, octanoic acid, azelaic acid, sebacic acid, undecanoic acid, dodecanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecanoic acid, and octadecanoic acid.

[0071] Advantageously, the at least one Yb dicarboxylic acid is C6 to C12, and is selected from succinic acid, octanoic acid, azelaic acid, sebacic acid, undecanoic acid, and dodecanoic acid.

[0072] Advantageously, the at least one Yb dicarboxylic acid is C10 to C12 and is selected from sebacic acid, undecanoic acid and dodecanoic acid.

[0073] When the semicrystalline aliphatic polyamide is obtained from the polycondensation of at least one Xa diamine and at least one Yb dicarboxylic acid, it may therefore include a single diamine or multiple diamines and a single dicarboxylic acid or several dicarboxylic acids.

[0074] Advantageously, the semicrystalline aliphatic polyamide is obtained from the polycondensation of a single Xa diamine and a single Yb dicarboxylic acid.

[0075] The at least one semi-aromatic semi-crystalline polyamide is obtained from the polycondensation of at least one Xa diamine as defined above with at least one aromatic dicarboxylic acid, or from the polycondensation of Xb diamine and Yb dicarboxylic acid as defined above.

[0076] The aromatic dicarboxylic acid is advantageously selected from terephthalic acid (denoted as T), isophthalic acid (denoted as I) and 2,6-naphthalenedicarboxylic acid (denoted as N) or mixtures thereof; particularly, the aromatic dicarboxylic acid is selected from terephthalic acid (denoted as T), isophthalic acid (denoted as I) or mixtures thereof.

[0077] Xb diamine is advantageously an aromatic diamine, which may be selected from m-phenylenediamine (MXD, CAS No. 1477-55-0) or p-phenylenediamine (PXD, CAS No. 539-48-0).

[0078] When the semi-crystalline semi-aromatic polyamide is obtained from the polycondensation of at least one Xa diamine and at least one aromatic dicarboxylic acid, or the polycondensation of at least one Xb diamine and at least one Yb dicarboxylic acid, it may therefore include a single diamine or multiple diamines and a single dicarboxylic acid or several dicarboxylic acids.

[0079] Advantageously, the semicrystalline aliphatic polyamide is obtained from the polycondensation of a single Xa diamine with a single aromatic dicarboxylic acid, or the polycondensation of a single Xb diamine with a single Yb dicarboxylic acid.

[0080] Advantageously, the semi-crystalline semi-aromatic polyamide is obtained from the polycondensation of at least one Xa diamine with at least one dicarboxylic acid selected from terephthalic acid and isophthalic acid, especially terephthalic acid, or the semi-aromatic semi-crystalline polyamide is obtained from the polycondensation of at least one Xb diamine with at least one Yb dicarboxylic acid.

[0081] Specifically, the at least one C6-C12Xa diamine 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 selected from terephthalic acid and isophthalic acid, especially terephthalic acid.

[0082] Specifically, the at least one Xb diamine is an aromatic amine, which may be selected from m-phenylenediamine (MXD, CAS No. 1477-55-0) or p-phenylenediamine (PXD, CAS No.: 539-48-0), and the at least one Yb dicarboxylic acid is C6 to C18, and may be selected from succinic acid, octanoic acid, azelaic acid, sebacic acid, undecanoic acid, dodecanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecanoic acid, and octadecanoic acid.

[0083] Advantageously, the at least one Yb dicarboxylic acid is C6 to C12, and is selected from succinic acid, octanoic acid, azelaic acid, sebacic acid, undecanoic acid, and dodecanoic acid.

[0084] These semi-aromatic polyamides can each copolymerize with lactams or amino acids to produce structures such as PA11 / 9T, PA11 / 10T, PA11 / 12T, PA12 / 9T, PA12 / 10T and PA12 / 12T or PA11 / MXD6, PA11 / MXD10, PA12 / MXD6 and PA12 / MXD10.

[0085] Advantageously, the composition of layer (1) comprises at least 60% by weight, particularly at least 70% by weight, especially at least 80% by weight, and more particularly at least 90% by weight, of a polyamide resin comprising at least one first polyamide resin mainly comprising aliphatic units and at least one second resin mainly comprising aromatic units, relative to the total weight of the composition.

[0086] The composition of layer (1) comprises at least 50% recycled material from multilayer pipes that have been used to transport fluids for motor vehicles.

[0087] This means that "at least one major polyamide" in the composition corresponds entirely to the so-called "at least 50% recycled material", or that at least 50% by weight of the overall composition is derived from a recycled source of multilayer tubes.

[0088] The recycled material may come from multi-layer pipes that have been used for fluid transport in motor vehicles. These pipes are therefore used pipes, meaning they have been used to transport the fluids defined above for at least one year.

[0089] The multilayer tube comprises at least one layer containing a composition including a semi-crystalline aliphatic polyamide and optional impact modifiers and / or additives, and at least one layer containing a blend of semi-crystalline aliphatic and semi-crystalline aromatic polyamides and optional impact modifiers and / or additives. It may therefore also include other layers made of a thermoplastic polymer (e.g., polypropylene, semi-aromatic polyamide, or polyvinyl alcohol (EVOH)) other than a blend of semi-crystalline aliphatic polyamide or a blend of semi-crystalline aliphatic and semi-crystalline aromatic polyamides.

[0090] It is also obvious that multilayer tubes can also be blends of different types of multilayer tubes, provided that at least one layer of a type of multilayer tube contains a semi-crystalline aliphatic polyamide.

[0091] If the mixing tubes are incompatible with each other, add one labeled B and with a label labeled C. B =Cc–1, preferably C B The second semi-crystalline aliphatic polyamide and preferably the third polyamide, having an average number of carbon atoms per nitrogen atom of Cc–2, are made compatible.

[0092] The multilayer tubing, which has been used to transport fluids for motor vehicles and is therefore used in this way, can undergo several different treatments for regeneration:

[0093] The multilayer tube can be easily shredded;

[0094] The multilayer tubes can be shredded and remixed, i.e., after shredding, the shredded particles are fed into an extruder, particularly a co-rotating twin-screw or bus-type extruder, where they are premixed by melt melting. The molten material exits the extruder as rods, which are cooled and cut into pellets;

[0095] The multilayer tubes can be shredded and re-blended for re-formulation, i.e., after shredding, the shredded particles are fed into an extruder, as defined above, where they are re-blended by melting with the addition of at least one compound selected from recycled or non-recycled semi-crystalline aliphatic polyamides, at least one impact modifier, plasticizer, additive, and antistatic additive. The molten material exits the extruder as rods, which are cooled and cut into pellets.

[0096] Optionally, multi-layer pipes that have always been used to transport fluids for motor vehicles undergo washing and / or cleaning steps before being shredded.

[0097] Optionally, the shredded tubes undergo washing and / or cleaning steps after shredding.

[0098] Optionally, the multilayer pipe used for conveying fluids for motor vehicles undergoes a washing and / or cleaning step before being shredded, and then optionally after shredding and before remixing.

[0099] The cleaning process can be carried out, for example, in a vacuum.

[0100] In one embodiment, the composition of layer (1) comprises:

[0101] At least 50% by weight, particularly 50% to 99% by weight, especially 50% to 98% by weight, of at least one semicrystalline aliphatic polyamide designated C, having a C value between 6 and 18, advantageously 8 to 12.C The average number of carbon atoms per nitrogen atom;

[0102] At least one of the following, designated B, comprising 0 to 50% by weight, and having the following designation C: B =Cc–1, with preference given to C B =Cc–2 semicrystalline aliphatic polyamide with an average number of carbon atoms per nitrogen atom;

[0103] 0 to 50% by weight of a semi-crystalline aliphatic polyamide denoted as A, which has the properties denoted as C A =C B –1. Preferably, C A =C B -2 is the average number of carbon atoms per nitrogen atom;

[0104] At least one impact modifier, in particular 1 to 45% by weight, and especially 2 to 45% by weight;

[0105] At least one plasticizer, ranging from 0 to 20% by weight.

[0106] At least one additive, ranging from 0 to 2% by weight.

[0107] The sum of the components equals 100%.

[0108] In another embodiment, the composition of layer (1) comprises the following:

[0109] At least 50% by weight, particularly 50% to 99% by weight, especially 50% to 98% by weight, of at least one semicrystalline aliphatic polyamide designated C, having a C value between 6 and 18, advantageously 8 to 12. C The average number of carbon atoms per nitrogen atom;

[0110] At least one of the following, designated B, comprising 0 to 25% by weight, and having the following designation C: B =Cc–1, preferably C B =Cc–2 semicrystalline aliphatic polyamide with an average number of carbon atoms per nitrogen atom;

[0111] 0 to 25% by weight of a semi-crystalline aliphatic polyamide denoted as A, which has the properties denoted as C A =C B –1. Preferably, C A =C B -2 is the average number of carbon atoms per nitrogen atom;

[0112] At least one impact modifier, in particular 1 to 45% by weight, and especially 2 to 45% by weight;

[0113] 0% to 20% of at least one plasticizer,

[0114] At least one additive, ranging from 0 to 2% by weight.

[0115] The sum of the components equals 100%.

[0116] The polyamides, designated A, B, and C, may be of recycled or non-recycled origin, provided that the composition of layer (1) contains at least 50% recycled material.

[0117] Advantageously, the Tm of the main aliphatic semicrystalline polyamide of layer (1) is ≤225°C, especially ≤200°C, as determined according to ISO 11357-3:2013 at a heating rate of 20 K / min.

[0118] In one embodiment, the composition of layer (1) lacks plasticizers and / or impact modifiers, and the recycled material is derived from pipes selected from: shredded pipes, shredded and remixed pipes, and shredded, remixed and reformulated pipes.

[0119] In another embodiment, the composition of layer (1) includes at least one compound selected from plasticizers, impact modifiers and additives, and the recycled material is selected from pipes that have been shredded, then remixed and reformulated.

[0120] In one embodiment, the fluid transported by the multilayer tube is different from the fluid transported by the multilayer tubular structure (MLT).

[0121] This means that if the multi-layer tube carries a fluid such as air, the multi-layer tube structure (MLT) may be intended for transporting gasoline, or if the multi-layer tube carries a fluid such as ethanol gasoline, the multi-layer tube structure (MLT) may be intended for transporting diesel.

[0122] In another embodiment, the fluid transported by the multilayer tube is the same as the fluid transported by the multilayer tubular structure (MLT).

[0123] This means that if the multilayer tube is always transporting a fluid such as gasoline, then the tubular structure (MLT) can be intended to be used to transport gasoline, provided that the multilayer tube and the multilayer tubular structure (MLT) are carrying the same type of gasoline, such as ethanol gasoline.

[0124] Advantageously, the recycled material comes from multilayer tubes such as PA11 / / PPA9T and PA12 / / PPA9T or PA11 / / MXD6 and PA12 / / MXD6.

[0125] In one embodiment, the composition of layer (1) comprises at least 60% by weight, particularly at least 70% by weight, particularly at least 80% by weight, especially at least 90% by weight, and more particularly at least 95% by weight of recycled material.

[0126] In another embodiment, the composition of layer (1) comprises 100% by weight of recycled material.

[0127] Regenerated used multilayer pipes

[0128] In the first variant, the pipe intended for conveying fluids for motor vehicles is multi-layered and simply shredded, and the composition of the regenerated layer (1) comprises the following:

[0129] At least 61% by weight, particularly 96% to 99% by weight, particularly 96% to 98% by weight of at least one semi-crystalline aliphatic polyamide designated C, having an average number of carbon atoms per nitrogen atom designated CC, between 6 and 18, advantageously 8 to 12, and at least one semi-crystalline semi-aromatic polyamide.

[0130] At least one plasticizer, from 0 to 2%,

[0131] At least one additive, particularly a stabilizer, at 0 to 2% by weight;

[0132] The sum of the components equals 100%.

[0133] Advantageously, in this first variant, the semi-crystalline aliphatic polyamide denoted as C is selected from PA612, PA1012, PA1010, PA11 and PA12, especially PA11, and the semi-crystalline semi-aromatic polyamide is selected from PA9T, PA10T, PA12T, MXD6 and MXD10.

[0134] Advantageously, in this first variant, the pipe is intended for conveying fuel, such as gasoline (especially ethanol gasoline, biogas), or diesel (especially biodiesel).

[0135] Advantageously, in this first variant, the semi-crystalline aliphatic polyamide designated C is selected from PA612, PA1012, PA1010, PA11 and PA12, especially PA11, and the semi-crystalline semi-aromatic polyamide is selected from PA9T, PA10T, PA12T, MXD6 and MXD10, and the tube is intended for conveying fuel, such as gasoline (especially ethanol gasoline, biogas) or diesel (especially biodiesel).

[0136] In the second variant, the pipe intended for conveying fluids for motor vehicles is multi-layered, and is shredded and remixed, and the composition of the regenerated layer (1) comprises the following:

[0137] At least 61% by weight, particularly 96% to 99% by weight, especially 96% to 98% by weight, of at least one semicrystalline aliphatic polyamide designated C, having a C value between 6 and 18, advantageously 8 to 12. C The average number of carbon atoms per nitrogen atom, and at least one semi-crystalline semi-aromatic polyamide;

[0138] At least one plasticizer, ranging from 0% to 2%,

[0139] At least one additive, particularly a stabilizer, at 0 to 2% by weight;

[0140] The sum of the components equals 100%.

[0141] Advantageously, in this second variant, the semi-crystalline aliphatic polyamide denoted as C is selected from PA612, PA1012, PA1010, PA11 and PA12, especially PA11, and the semi-crystalline semi-aromatic polyamide is selected from PA9T, PA10T, PA12T, MXD6 and MXD10.

[0142] Advantageously, in this second variant, the pipe is intended for conveying fuel, such as gasoline (especially ethanol gasoline, biogas), or diesel (especially biodiesel).

[0143] Advantageously in this second variant, the semi-crystalline aliphatic polyamide designated C is selected from PA612, PA1012, PA1010, PA11 and PA12, especially PA11, and the semi-crystalline semi-aromatic polyamide is selected from PA9T, PA10T, PA12T, MXD6 and MXD10, and the tube is intended for conveying fuel, such as gasoline (especially ethanol gasoline, biogas) or diesel (especially biodiesel).

[0144] In the third variant, the pipe intended for conveying fluids for motor vehicles is multi-layered and is shredded, remixed, and reformulated, and the composition of the layer (1) obtained from the regeneration and reformulation comprises the following:

[0145] At least 58.5% by weight of at least one semi-crystalline aliphatic polyamide designated C, having a C value between 6 and 18, advantageously between 8 and 12. C The average number of carbon atoms per nitrogen atom, and at least one semi-crystalline semi-aromatic polyamide;

[0146] At least one plasticizer, ranging from 6% to 14%, particularly from 6% to 8%;

[0147] At least one additive, particularly a stabilizer, at 0.5 to 1.5% by weight;

[0148] The sum of the components equals 100%.

[0149] Advantageously, in this third variant, the semi-crystalline aliphatic polyamide denoted as C is selected from PA612, PA1012, PA1010, PA11 and PA12, especially PA11, and the semi-crystalline semi-aromatic polyamide is selected from PA9T, PA10T, PA12T, MXD6 and MXD10.

[0150] Advantageously, in this third variant, the pipe is intended for transporting fuel, such as gasoline (especially ethanol gasoline, biogas), or diesel (especially biodiesel).

[0151] Advantageously in this third variant, the semi-crystalline aliphatic polyamide designated C is selected from PA612, PA1012, PA1010, PA11 and PA12, especially PA11, and the semi-crystalline semi-aromatic polyamide is selected from PA9T, PA10T, PA12T, MXD6 and MXD10, and the tube is intended for conveying fuel, such as gasoline (especially ethanol gasoline, biogas) or diesel (especially biodiesel).

[0152] In the fourth variant, the pipe intended for conveying fluids for motor vehicles is multi-layered and is shredded, remixed, and reformulated, and the composition of the layer (1) obtained from the regeneration and reformulation comprises the following:

[0153] At least 58% by weight of at least one semi-crystalline aliphatic polyamide designated C, having a C value between 6 and 18, advantageously between 8 and 12. C The average number of carbon atoms per nitrogen atom, and at least one semi-crystalline semi-aromatic polyamide;

[0154] At least one plasticizer, ranging from 6% to 14%, particularly from 6% to 8%;

[0155] At least one additive, particularly a stabilizer and a catalyst, at 1 to 2% by weight;

[0156] The sum of the components equals 100%.

[0157] Advantageously, in this fourth variant, the semi-crystalline aliphatic polyamide denoted as C is selected from PA612, PA1012, PA1010, PA11 and PA12, especially PA11, and the semi-crystalline semi-aromatic polyamide is selected from PA9T, PA10T, PA12T, MXD6 and MXD10.

[0158] Advantageously, in this fourth variant, the pipe is intended for conveying fuel, such as gasoline (especially ethanol gasoline, biogas), or diesel (especially biodiesel).

[0159] Advantageously in this fourth variant, the semi-crystalline aliphatic polyamide designated C is selected from PA612, PA1012, PA1010, PA11 and PA12, especially PA11, and the semi-crystalline semi-aromatic polyamide is selected from PA9T, PA10T, PA12T, MXD6 and MXD10, and the tube is intended for conveying fuel, such as gasoline (especially ethanol gasoline, biogas) or diesel (especially biodiesel).

[0160] Advantageously, the composition is degassed during compounding, and even more advantageously, this degassed degasses immediately after the molten zone and before the zone in which a plasticizer (e.g., BBSA or others) is introduced.

[0161] In the fifth variant, the pipe intended for conveying fluids for motor vehicles is multi-layered and is shredded, remixed, and reformulated, and the composition of the layer (1) obtained from the regeneration and reformulation comprises the following:

[0162] At least 50% by weight, particularly 50% to 99% by weight, especially 50% to 98% by weight, of at least one semicrystalline aliphatic polyamide designated C, having a C value between 6 and 18, advantageously 8 to 12. C The average number of carbon atoms per nitrogen atom, and at least one semi-crystalline semi-aromatic polyamide;

[0163] At least one of the following, designated B, comprising 0 to 25% by weight, and having the following designation C: B =Cc–1, with preference given to C B =Cc–2 semicrystalline aliphatic polyamide with an average number of carbon atoms per nitrogen atom;

[0164] 0 to 25% by weight of a semi-crystalline aliphatic polyamide denoted as A, which has the properties denoted as C A =C B –1. Prioritize C A =C B -2 is the average number of carbon atoms per nitrogen atom;

[0165] 0 to 2% of at least one plasticizer,

[0166] At least one additive, ranging from 0 to 2% by weight.

[0167] The sum of the components equals 100%.

[0168] Advantageously, in this fifth variant, the semi-crystalline aliphatic polyamide denoted as C is selected from PA612, PA1012, PA1010, PA11 and PA12, especially PA11, and the semi-crystalline semi-aromatic polyamide is selected from PA9T, PA10T, PA12T, MXD6 and MXD10.

[0169] Advantageously, in this fifth variant, the pipe is intended for conveying fuel, such as gasoline (especially ethanol gasoline, biogas), or diesel (especially biodiesel).

[0170] Advantageously, in this fifth variant, the semi-crystalline aliphatic polyamide designated C is selected from PA612, PA1012, PA1010, PA11 and PA12, especially PA11, and the semi-crystalline semi-aromatic polyamide is selected from PA9T, PA10T, PA12T, MXD6 and MXD10, and the tube is intended for conveying fuel, such as gasoline (especially ethanol gasoline, biogas) or diesel (especially biodiesel).

[0171] In the sixth variant, the pipe intended for conveying fluids for motor vehicles is multi-layered and is shredded, remixed, and reformulated, and the composition of the layer (1) obtained from the regeneration and reformulation comprises the following:

[0172] At least 55% by weight, particularly 55% to 99% by weight, especially 55% to 98% by weight, of at least one semi-crystalline aliphatic polyamide designated C, having a C value between 6 and 18, advantageously 8 to 12. C The average number of carbon atoms per nitrogen atom, and at least one semi-crystalline semi-aromatic polyamide;

[0173] At least one impact modifier, in particular at least one impact modifier, in the range of 0 to 45% by weight, especially at least one impact modifier, in particular at least one impact modifier, in the range of 2 to 45% by weight.

[0174] The sum of the components equals 100%.

[0175] Advantageously, in this sixth variant, the semi-crystalline aliphatic polyamide denoted as C is selected from PA612, PA1012, PA1010, PA11 and PA12, especially PA11, and the semi-crystalline semi-aromatic polyamide is selected from PA9T, PA10T, PA12T, MXD6 and MXD10.

[0176] Advantageously, in this sixth variant, the pipe is intended for conveying fuel, such as gasoline (especially ethanol gasoline, biogas), or diesel (especially biodiesel).

[0177] Advantageously, in this sixth variant, the semi-crystalline aliphatic polyamide designated C is selected from PA612, PA1012, PA1010, PA11 and PA12, especially PA11, and the semi-crystalline semi-aromatic polyamide is selected from PA9T, PA10T, PA12T, MXD6 and MXD10, and the tube is intended for conveying fuel, such as gasoline (especially ethanol gasoline, biogas) or diesel (especially biodiesel).

[0178] In the seventh variant, the pipe intended for conveying fluids for motor vehicles is multi-layered and is shredded, remixed, and reformulated, and the composition of the layer (1) obtained from the regeneration and reformulation comprises the following:

[0179] At least 50% by weight of at least one semi-crystalline aliphatic polyamide designated C, having a C value between 6 and 18, advantageously between 8 and 12. C The average number of carbon atoms per nitrogen atom, and at least one semi-crystalline semi-aromatic polyamide;

[0180] At least one impact modifier, in particular at least one impact modifier, in the amount of 0 to 43.5% by weight, especially at least one impact modifier, in the amount of 1 to 43.5% by weight, particularly at least one impact modifier, in the amount of 2 to 43.5% by weight.

[0181] At least one plasticizer, ranging from 6% to 14%, particularly from 6% to 8%;

[0182] At least one additive, particularly a stabilizer, at 0.5 to 1.5% by weight;

[0183] The sum of the components equals 100%.

[0184] Advantageously, in this seventh variant, the semi-crystalline aliphatic polyamide denoted as C is selected from PA612, PA1012, PA1010, PA11 and PA12, especially PA11, and the semi-crystalline semi-aromatic polyamide is selected from PA9T, PA10T, PA12T, MXD6 and MXD10.

[0185] Advantageously, in this seventh variant, the pipe is intended for conveying fuel, such as gasoline (especially ethanol gasoline, biogas), or diesel (especially biodiesel).

[0186] Advantageously, in this seventh variant, the semi-crystalline aliphatic polyamide designated C is selected from PA612, PA1012, PA1010, PA11 and PA12, especially PA11, and the semi-crystalline semi-aromatic polyamide is selected from PA9T, PA10T, PA12T, MXD6 and MXD10, and the pipe is intended for conveying fuel, such as gasoline (especially ethanol gasoline, biogas) or diesel (especially biodiesel).

[0187] In the eighth variant, the pipe intended for conveying fluids for motor vehicles is multi-layered and is shredded, remixed, and reformulated, and the composition of the layer (1) obtained from the regeneration and reformulation comprises the following:

[0188] At least 50% by weight of at least one semi-crystalline aliphatic polyamide designated C, having a C value between 6 and 18, advantageously between 8 and 12. CThe average number of carbon atoms per nitrogen atom, and at least one semi-crystalline semi-aromatic polyamide;

[0189] At least one impact modifier, in particular 1 to 43% by weight, and especially 2 to 38% by weight, of the same type of impact modifier.

[0190] At least one plasticizer, ranging from 6% to 14%, particularly from 6% to 8%;

[0191] At least one additive, particularly a stabilizer and a catalyst, at 1 to 2% by weight;

[0192] The sum of the components equals 100%.

[0193] Advantageously, in this eighth variant, the semi-crystalline aliphatic polyamide designated C is selected from PA612, PA1012, PA1010, PA11 and PA12, especially PA11, and the semi-crystalline semi-aromatic polyamide is selected from PA9T, PA10T, PA12T, MXD6 and MXD10.

[0194] Advantageously, in this eighth variant, the pipe is intended for conveying fuel, such as gasoline (especially ethanol gasoline, biogas), or diesel (especially biodiesel).

[0195] Advantageously, in this eighth variant, the semi-crystalline aliphatic polyamide designated C is selected from PA612, PA1012, PA1010, PA11 and PA12, especially PA11, and the semi-crystalline semi-aromatic polyamide is selected from PA9T, PA10T, PA12T, MXD6 and MXD10, and the tube is intended for conveying fuel, such as gasoline (especially ethanol gasoline, biogas) or diesel (especially biodiesel).

[0196] In the ninth variant, the pipe intended for conveying fluids for motor vehicles is multi-layered and is shredded, remixed, and reformulated, and the composition of the layer (1) obtained from the regeneration and reformulation comprises the following:

[0197] At least 50% by weight of at least one semi-crystalline aliphatic polyamide designated C, having a C value between 6 and 18, advantageously between 8 and 12. C The average number of carbon atoms per nitrogen atom, and at least one semi-crystalline semi-aromatic polyamide;

[0198] At least one of the following, designated B, comprising 0 to 25% by weight, and having the following designation C: B =Cc–1, with preference given to C B =Cc–2 semicrystalline aliphatic polyamide with an average number of carbon atoms per nitrogen atom;

[0199] 0 to 25% by weight of a semi-crystalline aliphatic polyamide denoted as A, which has the properties denoted as C A =C B –1. Prioritize C A =C B -2 is the average number of carbon atoms per nitrogen atom;

[0200] At least one impact modifier, in particular 1 to 43% by weight, and especially 2 to 38% by weight, of the same type of impact modifier.

[0201] 0% to 20% of at least one plasticizer,

[0202] At least one additive, ranging from 0 to 2% by weight.

[0203] The sum of the components equals 100%.

[0204] Advantageously, in this ninth variant, the semi-crystalline aliphatic polyamide denoted as C is selected from PA612, PA1012, PA1010, PA11 and PA12, especially PA11, and the semi-crystalline semi-aromatic polyamide is selected from PA9T, PA10T, PA12T, MXD6 and MXD10.

[0205] Advantageously, in this ninth variant, the pipe is intended for conveying fuel, such as gasoline (especially ethanol gasoline, biogas), or diesel (especially biodiesel).

[0206] Advantageously, in this ninth variant, the semi-crystalline aliphatic polyamide designated C is selected from PA612, PA1012, PA1010, PA11 and PA12, especially PA11, and the semi-crystalline semi-aromatic polyamide is selected from PA9T, PA10T, PA12T, MXD6 and MXD10, and the tube is intended for conveying fuel, such as gasoline (especially ethanol gasoline, biogas) or diesel (especially biodiesel).

[0207] Regarding impact modifiers

[0208] Impact modifiers advantageously comprise polymers having a flexural modulus below 100 MPa at 23°C and relative humidity RH 50%, as measured according to standard ISO 178:2010, and a Tg below 0°C (measured at the inflection point of a DSC thermogram at a heating rate of 20 K / min according to ISO 11357-2:2013), particularly polyolefins.

[0209] The impact modifier may be a functionalized or non-functionalized polyolefin, or a mixture of at least one functionalized polyolefin and / or at least one non-functionalized polyolefin. In short, the polyolefin is denoted as (B), and the functionalized polyolefin (B1) and the non-functionalized polyolefin (B2) are as follows.

[0210] Nonfunctionalized polyolefins (B2) are traditionally homopolymers or copolymers of α-olefins or dienes (e.g., ethylene, propylene, 1-butene, 1-octene, butadiene). Examples may be mentioned:

[0211] - Homopolymers and copolymers of polyethylene, especially LDPE, HDPE, LLDPE (linear low-density polyethylene), VLDPE (very low-density polyethylene), and metallocene polyethylene.

[0212] - Homopolymers or copolymers of propylene.

[0213] - Ethylene / α-olefin copolymers, such as ethylene / propylene, EPR (an abbreviation for ethylene-propylene-rubber), and ethylene / propylene / diene (EPDM).

[0214] - Styrene / ethylene-butene / styrene (SEBS), styrene / butadiene / styrene (SBS), styrene / isoprene / styrene (SIS), styrene / ethylene-propylene / styrene (SEPS) block copolymers.

[0215] - A copolymer of ethylene with at least one product selected from: a salt or ester of an unsaturated carboxylic acid, such as an alkyl methacrylate (e.g., methyl acrylate), or an ethylene ester of a saturated carboxylic acid, such as vinyl acetate (EVA), wherein the proportion of comonomers may reach 40% by weight.

[0216] Functionalized polyolefins (B1) can be polymers of α-olefins having reactive units (functional groups); such reactive units are acids, anhydrides, or epoxy functional groups. By way of example, the aforementioned polyolefins (B2) grafted, copolymerized, or ternarily polymerized by: unsaturated epoxides, such as glycidyl (meth)acrylate, or carboxylic acids or their corresponding salts or esters, such as (meth)acrylic acid (which may be completely or partially neutralized by metals such as Zn), or even carboxylic anhydrides, such as maleic anhydride. The functionalized polyolefin is, for example, a PE / EPR mixture, the weight ratio of which can vary widely, for example between 40 / 60 and 90 / 10, said mixture being co-grafted with anhydrides, particularly maleic anhydride, at a grafting rate of, for example, from 0.01 to 5% by weight.

[0217] The functionalized polyolefin (B1) may be selected from the following (co)polymers grafted with maleic anhydride or glycidyl methacrylate, wherein the grafting rate is, for example, from 0.01 to 5% by weight:

[0218] -PE, PP, copolymers of ethylene with propylene, butene, hexene, or octene containing, for example, 35-80% by weight of ethylene;

[0219] 1-Ethylene / α-olefin copolymers, such as ethylene / propylene, EPR (an abbreviation for ethylene-propylene-rubber), and ethylene / propylene / diene (EPDM).

[0220] - Styrene / ethylene-butene / styrene (SEBS), styrene / butadiene / styrene (SBS), styrene / isoprene / styrene (SIS), styrene / ethylene-propylene / styrene (SEPS) block copolymers.

[0221] - Ethylene and vinyl acetate copolymer (EVA) containing up to 40% by weight of vinyl acetate;

[0222] - An ethylene and (meth)acrylate copolymer containing up to 40% by weight of (meth)acrylate;

[0223] - Ethylene and vinyl acetate (EVA) and (meth)acrylate alkyl ester copolymers, which contain up to 40% by weight of comonomers.

[0224] Functionalized polyolefins (B1) may also be selected from ethylene / propylene copolymers having propylene primarily grafted with maleic anhydride and then condensed with monoamine polyamides (or polyamide oligomers) (products described in EP-A-0,342,066).

[0225] Functionalized polyolefins (B1) may also be copolymers or terpolymers of at least the following units: (1) ethylene, (2) alkyl esters of (meth)acrylate or ethylene esters of saturated carboxylic acids, and (3) anhydrides such as maleic anhydride, or (meth)acrylate, or epoxides such as glycidyl methacrylate.

[0226] Examples of functionalized polyolefins of a later type include copolymers in which ethylene preferably constitutes at least 60% by weight of the copolymer, and in which the ternary comonomer (functional group) constitutes, for example, 0.1 to 10% by weight of the copolymer:

[0227] - Ethylene / (meth)acrylate alkyl ester / (meth)acrylic acid or maleic anhydride or glycidyl methacrylate copolymer;

[0228] - Ethylene / vinyl acetate / maleic anhydride or glycidyl methacrylate copolymer;

[0229] - Ethylene / vinyl acetate or (meth)acrylate alkyl ester / (meth)acrylic acid or maleic anhydride or glycidyl methacrylate copolymer.

[0230] In the aforementioned copolymers, (meth)acrylic acid can form salts with Zn or Li.

[0231] The term “(meth)acrylate alkyl ester” in (B1) or (B2) means C1 to 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.

[0232] In addition, the aforementioned polyolefin (B1) can also be crosslinked by any suitable method or reagent (diepoxide, diacid, peroxide, etc.); the term functionalized polyolefin also includes the aforementioned polyolefin and a mixture of bifunctional reactants (e.g., diacid, diacid anhydride, diepoxide, etc.) that can react with it, or a mixture of at least two functionalized polyolefins that can react together.

[0233] The copolymers (B1) and (B2) described above can be copolymerized in a statistical or sequential manner and have linear or branched structures.

[0234] The molecular weight, melt flow index (MFI), and density of these polyolefins can vary widely, as will be known to those skilled in the art. MFI, an abbreviation for melt flow index, is a measure of fluidity in the molten state. It is measured according to the standard ASTM 1238.

[0235] Advantageously, the nonfunctionalized polyolefin (B2) is selected from homopolymers or copolymers of polypropylene and any homopolymers or copolymers of ethylene and higher α-olefin comonomers such as butene, hexene, octene, or 4-methyl-1-pentene. Examples include PP, high-density PE, medium-density PE, linear low-density PE, low-density PE, and very low-density PE. Those skilled in the art will recognize that these polyethylenes are produced according to a "free radical" method, a "Ziegler" catalytic method, or more recently, so-called "metallocene" catalysis.

[0236] Advantageously, the functionalized polyolefin (B1) is selected from any polymer comprising an α-olefin unit and a unit having a polar reactive functional group (e.g., epoxy, carboxylic acid, or carboxylic anhydride functional group). By way of examples of these polymers, ternary polymers of ethylene, alkyl acrylate, and maleic anhydride or glycidyl methacrylate (such as those from the applicant) may be mentioned. ), or polyolefins grafted with maleic anhydride, such as (from the applicant's ), and terpolymers of ethylene, alkyl acrylate and (meth)acrylic acid. Homopolymers or copolymers of polypropylene grafted with carboxylic anhydride and then condensed with polyamide or monoamine polyamide oligomers may also be mentioned.

[0237] About additives

[0238] The additives optionally used in the compositions of the present invention are conventional additives used in polyamides and are well known to those skilled in the art, and are particularly described in EP 2098580.

[0239] For example, they are selected from catalysts, antioxidants, heat stabilizers, UV absorbers, light stabilizers, lubricants, inorganic fillers, flame retardants, nucleating agents and dyes, reinforcing fibers, waxes, and mixtures thereof.

[0240] The term "catalyst" refers to a condensation catalyst, such as a mineral (inorganic) acid or an organic acid.

[0241] Advantageously, the catalyst is present in a weight ratio of about 50 ppm to about 5000 ppm, particularly about 100 to about 3000 ppm, relative to the total weight of the composition.

[0242] Advantageously, the catalyst is selected from phosphoric acid (H3PO4), phosphorous acid (H3PO3), hypophosphorous acid (H3PO2), or mixtures thereof.

[0243] As an example, the stabilizer may be a UV stabilizer, an organic stabilizer, or more generally a combination of organic stabilizers, such as a phenolic antioxidant (e.g., a Ciba-BASF model). 245 or 1098 or 1010), phosphite antioxidants (e.g., Ciba-BASF's) 126 and 168) and optional other stabilizers, such as HALS (meaning hindered amine light stabilizers, e.g., Ciba-BASF's) 770), UV resistant (e.g., Ciba's) 312), or phosphorus-based stabilizers. Amine antioxidants such as Crompton's can also be used. 445 or multifunctional stabilizers such as Clariant S-EED.

[0244] The stabilizer can also be a mineral stabilizer, such as a copper-based stabilizer. Examples of such mineral stabilizers include halides and copper acetate. Alternatively, other metals such as silver can be considered, but they are known to be less effective. These copper-based compounds are generally associated with alkali metal halides, particularly potassium.

[0245] Regarding plasticizers:

[0246] As examples, plasticizers are selected from: benzenesulfonamide derivatives, such as n-butylbenzenesulfonamide (BBSA); ethyl toluenesulfonamide or N-cyclohexyl toluenesulfonamide; hydroxybenzoic acid esters, such as 2-ethylhexyl p-hydroxybenzoate and 2-decyl hexyl p-hydroxybenzoate; esters or ethers of tetrahydrofurfuryl alcohol, such as oligoethyleneoxytetrahydrofurfuryl alcohol; and esters of citric acid or hydroxymalonic acid, such as oligoethyleneoxymalonate.

[0247] The use of plasticizer mixtures is not outside the scope of this invention.

[0248] When additives are present in the composition, the proportion is advantageously 1 to 20% by weight, particularly 5 to 15% by weight, and preferably 5 to 12% by weight.

[0249] Regarding antistatic fillers

[0250] Antistatic fillers are selected from materials such as carbon black, graphite, carbon fiber, and carbon nanotubes, especially carbon black and carbon nanotubes.

[0251] Regarding layer (2)

[0252] The terms “semi-crystalline polyamide” and “aliphatic” have the same definitions as for layer (1).

[0253] The at least one aliphatic semi-crystalline polyamide is obtained in the same manner as described above for layer (1).

[0254] In the first variant of layer (2), layer (2) lacks an impact modifier.

[0255] In this case, the semi-crystalline aliphatic polyamide, which is PA12, PA612, or PA1010, is excluded from the composition constituting layer (2).

[0256] In a second variant of layer (2), layer (2) comprises at least one impact modifier at 3 to 45% by weight, particularly at least one impact modifier at 5 to 20% by weight.

[0257] In one embodiment of this second variant, the layer (2) comprises a composition including:

[0258] At least 50% by weight, particularly 50% to 97% by weight, especially 50% to 95% by weight, of at least one semi-crystalline aliphatic polyamide designated D, having a C value between 6 and 18, advantageously 9 to 15. D The average number of carbon atoms per nitrogen atom;

[0259] At least one of the following, denoted as E, and having a weight of 0 to 25% and a weight of C E =C D –1. Prioritize C E =CD Semi-crystalline aliphatic polyamide with an average number of carbon atoms per nitrogen atom of -2;

[0260] 0 to 25% by weight of a semi-crystalline aliphatic polyamide denoted as F, which has the property denoted as C F =C E –1. Prioritize C F =C E -2;

[0261] At least one impact modifier, in particular at least 5 to 20% by weight, of 3 to 45% by weight;

[0262] At least one plasticizer, ranging from 0% to 20%;

[0263] At least one additive, ranging from 0 to 2% by weight.

[0264] 0% to 35% of at least one antistatic filler,

[0265] The sum of the components equals 100%.

[0266] In another embodiment of this second variant, the layer (2) comprises a composition including:

[0267] At least 50% by weight, particularly 50% to 97% by weight, especially 50% to 95% by weight, of at least one semi-crystalline aliphatic polyamide designated D, having a C value between 6 and 18, advantageously 9 to 15. D The average number of carbon atoms per nitrogen atom;

[0268] At least one of the following, denoted as E, and having a weight of 0 to 25% and a weight of C E =C D –1. Prioritize C E =C D Semi-crystalline aliphatic polyamide with an average number of carbon atoms per nitrogen atom of -2;

[0269] 0 to 25% by weight of a semi-crystalline aliphatic polyamide denoted as F, which has the property denoted as C F =C E –1. Prioritize C F =C E -2 is the average number of carbon atoms per nitrogen atom;

[0270] At least one impact modifier, in particular at least 5 to 20% by weight, of 3 to 45% by weight;

[0271] At least one plasticizer, ranging from 0% to 20%;

[0272] At least one additive, from 0 to 2% by weight,

[0273] 0% to 35% of at least one antistatic filler,

[0274] The sum of the components equals 100%.

[0275] Advantageously, the composition of the layer (2) includes PA11, PA12 or PA612, and 3 to 45% by weight of an impact modifier, particularly 5 to 20% by weight of an impact modifier.

[0276] Regarding layer (2')

[0277] The terms “semi-crystalline polyamide” and “aliphatic” have the same definitions as for layer (1) or layer (2).

[0278] The at least one aliphatic semi-crystalline polyamide is obtained in the same manner as described above for layers (1) and (2).

[0279] In the first variant of layer (2'), layer (2') lacks an impact modifier.

[0280] In a second variant of layer (2'), layer (2') contains 3 to 45% by weight of at least one impact modifier, particularly 5 to 20% by weight of at least one impact modifier.

[0281] In one embodiment of this second variant, the layer (2') comprises a composition including:

[0282] At least 50% by weight, particularly 50% to 97% by weight, especially 50% to 95% by weight, of at least one semi-crystalline aliphatic polyamide designated D, having a C value between 6 and 18, advantageously 9 to 15. D The average number of carbon atoms per nitrogen atom;

[0283] At least one of the following, denoted as E, and having a weight of 0 to 25% and a weight of C E =C D –1. Preferably, C E =C D Semi-crystalline aliphatic polyamide with an average number of carbon atoms per nitrogen atom of -2;

[0284] 0 to 25% by weight of a semi-crystalline aliphatic polyamide denoted as F, which has the property denoted as C F =C E –1. Preferably, C F =C E -2 is the average number of carbon atoms per nitrogen atom;

[0285] At least one impact modifier, in particular, at least 5 to 20% by weight;

[0286] At least one plasticizer, ranging from 0% to 20%;

[0287] At least one additive, ranging from 0 to 2% by weight.

[0288] 0% to 35% of at least one antistatic filler,

[0289] The sum of the components equals 100%.

[0290] In another embodiment of this second variant, the layer (2') comprises a composition including:

[0291] At least 50% by weight, particularly 50% to 97% by weight, especially 50% to 95% by weight, of at least one semi-crystalline aliphatic polyamide designated D, having a C value between 6 and 18, advantageously 9 to 15. D The average number of carbon atoms per nitrogen atom;

[0292] At least one of the following, denoted as E, and having a weight of 0 to 25% and a weight of C E =C D –1. Preferably, C E =C D Semi-crystalline aliphatic polyamide with an average number of carbon atoms per nitrogen atom of -2;

[0293] 0 to 25% by weight of a semi-crystalline aliphatic polyamide denoted as F, which has the property denoted as C F =C E –1. Preferably, C F =C E -2 is the average number of carbon atoms per nitrogen atom;

[0294] At least one impact modifier, in particular, at least 5 to 20% by weight;

[0295] At least one plasticizer, ranging from 0% to 20%;

[0296] At least one additive, ranging from 0 to 2% by weight.

[0297] 0% to 35% of at least one antistatic filler,

[0298] The sum of the components equals 100%.

[0299] Advantageously, the composition of the layer (2') comprises PA11, PA12 or PA612, and at least one impact modifier at 3 to 45% by weight, particularly at least one impact modifier at 5 to 20% by weight.

[0300] About the structure

[0301] All implementations of layer (1) described in the paragraph “About layer (1)” above can be used in the structure detailed in this section.

[0302] In one embodiment, the layer (1) is located between the layer (2) and the layer (2').

[0303] Advantageously, the layer (2') is a layer in contact with the transport fluid.

[0304] Advantageously, the layer (2') is as defined for layer (2), and preferably, layers (2) and (2') are the same.

[0305] In the following embodiments, the layer (2') is as defined for layer (2), meaning that the composition of layer (2) and layer (2') may be the same or different.

[0306] When they differ, the difference may be in the polyamide or the proportion of polyamide or one of the other components of the composition.

[0307] Advantageously, the composition of the layer (2) includes PA11, PA12 or PA612, and the recycled material comes from a multilayer tube containing a composition including PA11 or PA12 and PA9T, PA10T, PA12T, PAMXD6 and PAMXD10, and particularly the composition of the layer (1) contains 100% recycled material.

[0308] Advantageously, the composition of layer (2) comprises PA11, PA12 or PA612, and the recycled material comes from a multilayer tube comprising a composition comprising PA11 or PA12 and PA9T, PA10T, PA12T, PAMXD6 and PAMXD10, particularly the composition of layer (1) comprises 100% recycled material, and the composition of layer (2') comprises PA11, PA12 or PA612.

[0309] Advantageously, the layer (2) composition comprises PA11, PA12 or PA612, and at least one impact modifier at 3 to 45% by weight, particularly at least one impact modifier at 5 to 20% by weight, and the recycled material is derived from a multilayer tube comprising a composition comprising PA11 or PA12 and PA9T, PA10T, PA12T, PAMXD6 and PAMXD10, particularly the layer (1) composition comprising 100% recycled material.

[0310] Advantageously, the composition of layer (2) comprises PA11, PA12 or PA612, and at least one impact modifier by weight of 3 to 45% in particular 5 to 20% in particular 5 ...

[0311] Advantageously, the compositions of layer (2) and layer (2') are identical, therefore layers (2) and (2') are obviously identical, that is: the polyamide and other components of the composition are identical in properties and proportions, and the thicknesses of the two layers (2) and (2') are the same. In such a case, layer (2') is layer (2).

[0312] In the first variant of the multilayer tubular structure (MLT), it comprises three layers: (2) / / (1) / / (2'), and in particular (2) / / (1) / / (2).

[0313] In one embodiment, there is at least one adhesive layer (3) located between layer (2) and layer (1), and / or between layer (1) and layer (2').

[0314] In the second variant of the multilayer tubular structure (MLT), it comprises four layers: (2) / / adhesive (3) / / (1) / / (2'), and in particular (2) / / adhesive (3) / / (1) / / (2).

[0315] In the third variant of the multilayer tubular structure (MLT), it comprises four layers: (2) / / (1) / / adhesive (3) / / (2'), and in particular (2) / / (1) / / adhesive (3) / / (2).

[0316] In the fourth variant of the multilayer tubular structure (MLT), it comprises the following five layers: (2) / / adhesive (3) / / (1) / / adhesive (3) / / (2'), and in particular (2) / / adhesive (3) / / (1) / / adhesive (3) / / (2).

[0317] In this fourth variant, the two adhesive layers (3) may be the same or different, in particular they are the same.

[0318] In another embodiment, at least one EVOH layer is present, the layer (3) being located between layer (1) and layer (2').

[0319] In such a case, the multilayer tubular structure (MLT) comprises the following four layers: (2) / / (1) / / EVOH / / (2'), and in particular (2) / / (1) / / EVOH / / (2).

[0320] In one embodiment, the layer (1) accounts for at least 10%, particularly at least 30%, and especially at least 50% of the total thickness of the multilayer tubular structure (MLT).

[0321] Advantageously, the layer (1) accounts for at least 60%, particularly at least 70%, of the total thickness of the multilayer tubular structure (MLT).

[0322] In one of the four variants of the multilayer tubular structure (MLT) or in one embodiment of the four-layer structure having EVOH, the composition of layer (1) lacks polyamides designated A and B, and the composition of layer (2) comprises a polyamide selected from polyamides designated E, F and mixtures thereof.

[0323] In one of the four variants of the multilayer tubular structure (MLT) or another embodiment of the four-layer structure having EVOH, the composition of the layer (1) comprises a polyamide selected from polyamides denoted as A, B and mixtures thereof, and the composition of the layer (2) lacks polyamides denoted as E and F.

[0324] In one of the four variants of the multilayer tubular structure (MLT) or in another embodiment of the four-layer structure having EVOH, the composition of the layer (1) comprises a polyamide selected from polyamides designated A, B and mixtures thereof, and the composition of the layer (2) comprises a polyamide selected from polyamides designated E, F and mixtures thereof.

[0325] In one of the four variants of the multilayer tubular structure (MLT) or in another embodiment of the four-layer structure having EVOH, the composition of layer (1) lacks a polyamide selected from polyamides designated A and B, and the composition of layer (2) lacks polyamides designated E and F.

[0326] Advantageously, in these last four embodiments, layer (1) is derived from a regenerated multilayer tube.

[0327] Advantageously, in these latter four embodiments, layer (1) is derived from recycled multilayer tubes, and only the composition of layer (1) includes at least one impact modifier.

[0328] Advantageously, in these latter four embodiments, layer (1) is derived from recycled multilayer tubes, and the composition of layer (1) and the composition of layer (2) or layer (2') include at least one impact modifier.

[0329] In one embodiment, the multilayer tube (MLT) is used to transport a fluid selected from fuels such as gasoline (especially ethanol gasoline, biogas) or diesel (especially biodiesel).

[0330] Regarding adhesives

[0331] Adhesives are particularly described in patents EP1452307 and EP1162061, EP1216826, EP0428833 and EP3299165.

[0332] It goes without saying that layers (2) and (1) or (1) and (2') adhere to each other. The intention is to insert an adhesive layer between two layers that do not adhere to each other or have adhesion problems.

[0333] For example, but not limited to, the adhesive may be a composition based on 50% copolyamide 6 / 12 (70 / 30 by weight) and 50% copolyamide 6 / 12 (30 / 70 by weight) with 16,000 Mn, a composition based on PP (polypropylene) grafted with maleic anhydride (known from Mitsui as Admer QF551A), a composition based on PA610 (Mn 30,000, and otherwise defined) and 36% PA6 (Mn 28,000) and 1.2% organic stabilizer (containing 0.8% phenolic Lowinox 44B25 from Great Lakes, 0.2% phosphite Irgafos 168 from Ciba, and 0.2% UV-resistant Tinuvin from Ciba). Compositions based on PA612 (Mn of 29,000, and otherwise defined) and 36% PA6 (Mn of 28,000, and otherwise defined) and 1.2% organic stabilizers (containing 0.8% phenolic Lowinox 44B25 from Great Lakes, 0.2% phosphite Irgafos 168 from Ciba, and 0.2% UV-resistant Tinuvin 312 from Ciba); compositions based on PA610 (Mn of 30,000, and otherwise defined) and 36% PA12 (Mn of 35,000, and otherwise defined) and 1.2% organic stabilizers (containing 0.8% phenolic Lowinox 44B25 from Great Lakes, 0.2% phosphite Irgafos 168 from Ciba, and 0.2% UV-resistant Tinuvin 312 from Ciba). The composition of Tinuvin 312 is based on 40% PA6 (Mn of 28,000, and otherwise defined), 40% PA12 (Mn of 35,000, and otherwise defined), 20% functionalized EPREXxxelor VA1801 (from Exxon), and 1.2% organic stabilizers (containing 0.8% phenolic Lowinox 44B25 from Great Lakes, 0.2% phosphite Irgafos 168 from Ciba, and 0.2% UV-resistant Tinuvin from Ciba). Compositions of 312), or based on 40% PA6.10 (Mn of 30,000, and otherwise defined), 40% PA6 (Mn of 28,000, and otherwise defined), and 20% impact modifier of the ethylene / ethyl acrylate / anhydride type (MFI6 at 2.16 kg at 190°C) in a weight ratio of 68.5:30:1.5, and 1.2% organic stabilizer (containing 0.8% phenol Lowinox 44B25 from Great Lakes).2% from Ciba's phosphite Irgafos 168, 0.2% from Ciba's UV-resistant Tinuvin 312. Example:

[0334] The following resins have been consistently used in the various compositions of this invention:

[0335] PA11: Polyamide 11 with a number-average molecular weight of 29,000 Mn. Melting temperature is 190°C; its enthalpy of melting is 56 kJ / m². The composition of this PA11 includes 0.25% (+ / - 0.05%) H₃PO₄.

[0336] PA12: Polyamide 12 with a number-average molecular weight of 35,000 Mn. Its melting temperature is 178℃; its enthalpy of melting is 54 kJ / m².

[0337] PA12-B: Polyamide 12 with a number-average molecular weight of 41000 Mn. Its melting temperature is 178℃; its enthalpy of melting is 54 kJ / m².

[0338] PA1012: Polyamide 1012 with a number-average molecular weight of 27000 Mn. Its melting temperature is 190℃; its enthalpy of melting is 57 kJ / m².

[0339] PA612: Polyamide 612 with a number-average molecular weight of 29,000 Mn. Its melting temperature is 218℃; its enthalpy of melting is 67 kJ / m².

[0340] PA610: Polyamide 610 with a number-average molecular weight of 30,000 Mn. Its melting temperature is 223℃; its enthalpy of melting is 61 kJ / m².

[0341] PA6: Polyamide 6 with a number-average molecular weight of 28,000 Mn. Its melting temperature is 220℃; its enthalpy of melting is 68 kJ / m².

[0342] Melting temperature and enthalpy of fusion were determined according to standard ISO 11357-3:2013.

[0343] The following additives, plasticizers, and impact modifiers are used in the compositions of this invention:

[0344] Stabilizer: A stabilizer made from 80% Lowinox 44B25 phenol from Great Lakes and 20% Irgafos 168 phosphite from Ciba.

[0345] BBSA: Plasticizer BBSA (phenylbutylsulfonamide),

[0346] Imod generally refers to polyolefins or other types of impact modifiers, such as PEBA (polyether-block-amide), core-shell, silicone, etc.

[0347] Imod1: refers to Exxellor VA1801 from Exxon, which is functionalized by reactive groups (in 0.5 to 1% by mass) with anhydride functional groups, MFI 9 (at 230°C, hereinafter) 10 kg.

[0348] Imod2: An ethylene / ethyl acrylate / anhydride impact modifier with a mass ratio of 68.5 / 30 / 1.5 and an MFI 6 at 190°C and 2.16 kg.

[0349] Imod3: An ethylene / butyl acrylate / anhydride impact modifier with a mass ratio of 79 / 18 / 3 and an MFI of 5 at 190°C and 2.16 kg.

[0350] The tube according to the present invention is manufactured using the following composition:

[0351] Throughout the instruction manual, all percentages are expressed in terms of weight.

[0352] In the case of compositions named "recy", "recy2" and "recy3" (for layer (1) of the tube of the present invention or the comparative tube), the following scheme for simulating aging tubes has always been used:

[0353] Option A: The pipe is (artificially) aged according to a reproducible model scheme, which involves placing the pipe in air (in the presence of oxygen) at 150°C for 96 hours (4 days) to induce thermal oxidation. This model aging represents the average thermal oxidation experienced by the pipe during 10 years of service in a vehicle near a hot engine.

[0354] Results obtained in terms of impact, aging, flexural modulus, adhesion, and elongation indicate that Scheme A represents re-shredded gasoline tubing.

[0355] A special procedure used during the (re)blending of aging tubes.

[0356] After aging, the shredded tubes can be remixed in certain situations according to the following two schemes:

[0357] Option B: Re-mix the shredded tubes on a Coperion / Werner 40mm twin-screw (bivis) extruder at a set point of 70kgh, 300rpm, and 270℃ under degassing conditions at -100mmHg.

[0358] Option B2: Re-mix the shredded tubes on a Coperion / Werner 40mm twin-screw extruder at a set point of 70kgh, 300rpm, and 270℃ under strong degassing conditions at -660mmHg.

[0359] The following are various compositions used to prepare the tube of the present invention:

[0360] PA11PL = PA11 + 7% BBSA + 1% stabilizer

[0361] PA12PL = PA12 + 12% BBSA + 1% stabilizer

[0362] PA11PL-recy = PA11PL tubes aged according to scheme A, then shredded, and subsequently regenerated.

[0363] PA11PL-recy2 = Aging according to scheme A, then chopping, remixing according to scheme B2, and adding 7% BBSA + 0.5% stabilizer during this remixing process, followed by the regenerated PA11PL tubes.

[0364] PA11PL-recy + 50% PA12PL-recy = a 50 / 50 mixture of PA11PL-recy granules and PA12PL-recy granules.

[0365] 1012-recy = PA1012PL4 tubes that are aged according to scheme A, then shredded, and then regenerated.

[0366] PA11PL4 = PA11 + 12% BBSA + 1% stabilizer

[0367] PA12HIP-recy3 = Aged according to scheme A, then shredded, and remixed according to scheme B, with 6% imod1, 9% BBSA and 1% stabilizer added during this remixing; then intended for use in PA12HIPHL tubes for regeneration.

[0368] 11NX3 = PA11 + imod2 10% + PA610 5% + PA6 5% + BBSA 4% + stabilizer 1%

[0369] PA11PL-recy + 50% PA11PL = a 50 / 50 mixture of PA11PL-recy and PA11PL granules (recycled and virgin materials).

[0370] PA12HIPHL = PA12 + 6% imod1 + 10% BBSA + 1% stabilizer

[0371] PA12HIPHL-recy = PA12HIPHL tubes aged according to scheme A, then shredded, and subsequently regenerated.

[0372] PA12HIPHL-recy2 = Aging according to scheme A, then chopping, and remixing according to scheme B, with 10% BBSA + 0.5% stabilizer added during this remixing process. The resulting regenerated PA12HIPHL tubes...

[0373] PA12HIP-recy3 = Aged according to scheme A, then shredded, and remixed according to scheme B, with 6% imod1, 9% BBSA and 1% stabilizer added during this remixing; subsequently intended for use in regenerated PA12HIPHL tubes.

[0374] MLT-cx11-recy = MLT tubes that are aged according to scheme A, then shredded, remixed according to scheme B, and then regenerated (11NX3 / / OHhi / / 11NX3 45 / / 15 / / 40%).

[0375] MLT-cx21-recy = MLT tubes that are aged according to scheme A, then shredded, remixed according to scheme B, and then regenerated (11NX3 / / MXD6hi 80 / 20%).

[0376] MXD6hi = MXD6 impact-modified composition = a composition based on MXD6 type copolyamide, containing an impact modifier sold by Solvay under the name BXT-2000. Its melting point is 237°C.

[0377] MLT-cx11-recy + 20% MLTcx31-recy = a mixture of 80% MLT-cx11-recy and 20% MLT-cx31-recy

[0378] MLT-cx31-recy = MLT tubes that are aged according to scheme A, then shredded, remixed according to scheme B, and then regenerated (PA12HI2 / / PA11-recyNX3 / / PPA9T 15 / 60 / 25%).

[0379] PA12HI2 = PA12-B + 10% imod1 + 5% BBSA + 1% stabilizer

[0380] OHhi = Impact-modified EVOH, marketed by Eval-Kuraray under the name EVAL LA170B

[0381] These compositions are prepared by conventional compounding at 300 rpm and 270°C (or 300°C if the components have a melting point above 260°C) in a co-rotating twin-screw extruder (such as the Coperion 40).

[0382] This invention relates to multilayer tubes:

[0383] The layers are described from the outside in, followed by their respective thicknesses expressed as a percentage; the tube size is 8*1mm.

[0384] Fabrication of multilayer structures (tubes):

[0385] Multilayer tubes are produced by co-extrusion. An industrial Maillefer multilayer extrusion line is used, which is equipped with five extruders connected to multilayer extrusion heads with helical mandrels.

[0386] The screw used is a single extrusion screw with a screw profile (profile) suitable for polyamide. In addition to five extruders and a multi-layer extrusion head, the extrusion production line also includes:

[0387] The die-punch assembly is located at the end of the co-extrusion head; the die inner diameter and punch outer diameter are selected based on the structure to be produced, the materials that make it up, the tube size, and the line speed.

[0388] The vacuum chamber has an adjustable vacuum level. Water circulation within the chamber is typically maintained at 20°C, and calipers are immersed in it, allowing the tube to be shaped to its final dimensions. The caliper diameter is matched to the size of the tube to be produced, typically 8.5 to 10 mm for a tube with an outer diameter of 8 mm and a thickness of 1 mm.

[0389] A series of cooling tanks, in which water is maintained at approximately 20°C, allow the pipes to be cooled along the path from the head to the drawing table;

[0390] Diameter measuring instrument;

[0391] Pulling table.

[0392] A configuration with five extruders is used to manufacture tubes ranging from two to five layers (as well as single-layer tubes). In the case of structures with fewer than five layers, the same material is fed into several extruders.

[0393] Before testing, to ensure optimal tube properties and good extrusion quality, verify that the extruded material has a residual moisture content of less than 0.08% before extrusion. Otherwise, an additional pre-test material drying step (usually in a vacuum dryer) is performed overnight at 80°C.

[0394] After the extrusion parameters stabilize, the tubes that meet the characteristics disclosed in this patent application are removed, and the dimensions of the tubes involved no longer change over time. The diameter is controlled by a laser diameter measuring instrument installed at the end of the production line.

[0395] The production line speed is typically 20 m / min. Its typical range is 5 to 100 m / min.

[0396] The screw speed of an extruder depends on the layer thickness and screw diameter, as is known to those skilled in the art.

[0397] Typically, the temperature of the extruder and tools (head and connector) must be adjusted to be sufficiently above the melt temperature of the composition involved, so that they remain molten and thus prevent them from solidifying and clogging the machine.

[0398] Then, the multilayer tubes produced by extrusion are evaluated according to the following criteria:

[0399] Flexibility: refers to the flexural modulus measured according to ISO 178 at 23°C for pipes conditioned in a climate of 50% humidity and under equilibrium conditions at 23°C.

[0400] For bending performance that can be rated as "good" (corresponding to <= 1000 MPa and > 500 MPa), we denote it as "+".

[0401] For bending performance that can be rated as "very good" (corresponding to <= 500 MPa and > 250 MPa), we denote it as "++".

[0402] Impact: refers to the impact type VW-40℃ standard VW TL52435 2010

[0403] For impact performance that can be rated as "very good" (corresponding to a fracture rate of <=10%), we denote it as "++".

[0404] For impact performance that can be rated "good" (corresponding to a fracture rate of <= 25% and >10%), we denote it as "+".

[0405] Impact performance rated as "poor" (corresponding to a fracture rate of <= 75% and >25%) is denoted as "-".

[0406] For impact performance that can be rated as "very poor" (corresponding to >75%), we denote it as "--".

[0407] Aging: This refers to durability, also known as the tube's resistance to oxidative aging in hot air. The tube is aged in air at 150°C and then subjected to impact testing according to DIN 73378 at -40°C. We denote this as half-life (in hours), corresponding to a time at which 50% of the tested tubes have broken. This value is accompanied by a qualitative evaluation.

[0408] For durability that can be rated as "very good" (corresponding to a half-life of >= 200h), we denote it as "++".

[0409] For durability (resistance to thermal oxidative aging) that can be rated as "good" (corresponding to a half-life of >=100h (and <200h)), we denote it as "+".

[0410] For durability rated as "acceptable" (resistance to thermal oxidative aging) (corresponding to a half-life of ≥50h (and <100h)), we denote it as "+-".

[0411] For durability that can be described as "poor" (resistance to thermal oxidative aging) (corresponding to <50h), we denote it as "-".

[0412] In cases where a half-life figure is given to show subtle differences, the figure is rounded in 25-hour increments to account for significant figures relevant to the accuracy of the assessment.

[0413] Adhesion: This refers to the adhesion force. It is expressed in N / cm and is measured on the following tube: the tube is 8 mm in diameter and 1 mm thick, and has been conditioned at 50% relative humidity and 23°C for >=15 days to achieve moisture equilibrium within the sample.

[0414] The values ​​given are for the weakest interface, i.e., the one with the weakest adhesion in the multilayer, where the risk of delamination is greatest. Delamination at the interface is performed by pulling one of the components at a 90° angle and a speed of 50 mm / min.

[0415] Cut out a 9mm wide strip. This strip is therefore tile-shaped and still retains all the layers of the original tube. Begin separating the two layers of the interface we wish to evaluate using a cutting tool. Place each of the separated layers in the fixture of a pulling machine. Peeling is performed by pulling these two layers 180 degrees apart on both sides at a speed of 50mm / min. The strip and thus the interface are maintained at 90 degrees relative to the pulling direction.

[0416] We record it as:

[0417] +++: Excellent, >50

[0418] ++: Okay, >20 and <=50

[0419] +: Good (acceptable), >10 and <=20

[0420] -difference, <=10

[0421] Elongation %: This is the elongation at break according to ISO R527 standard, except as follows: it is measured for tubes with a diameter of 8 mm and a thickness of 1 mm. The samples are ISO conditioned, i.e., conditioned at 50% relative humidity and 23°C for >= 15 days to achieve moisture equilibrium within the sample.

[0422] We record it as:

[0423] +++: Excellent, >=200% elongation ++: Good, >=100 and <200% elongation +: Unsatisfactory: <100% elongation The results are shown in Table 1.

[0424] [Table 1]

[0425]

[0426] NT: Not tested

Claims

1. Multilayer tubular structure MLT for conveying a fluid for a motor vehicle, comprising at least three layers: at least one layer (1) comprising a composition comprising at least 50% of a polyamide resin comprising at least one first polyamide resin comprising predominantly aliphatic units and at least one second resin comprising predominantly aromatic units, said composition comprising at least 50% of recycled material from a multilayer tube, said multilayer tube having conveyed a fluid for a motor vehicle, said tube comprising a composition comprising predominantly at least one polyamide, at least one layer (2) comprising a composition comprising predominantly at least one semi-crystalline aliphatic polyamide and optionally at least one impact modifier, and when layer (2) comprises a composition comprising predominantly at least one semi-crystalline aliphatic polyamide which is PA 12 and / or PA 612 and / or PA 1010, then said composition comprises said impact modifier, and at least one layer (2') comprising a composition comprising predominantly at least one semi-crystalline aliphatic polyamide, said layer (2) and said layer (2') each comprising at least 90% of non-recycled material, wherein the recycled material is from a multilayer tube selected from the group consisting of a multilayer tube which has been shredded and recompounded, and a multilayer tube which has been shredded, recompounded and reprocessed.

2. Multilayer tubular structure MLT according to claim 1, wherein said multilayer tubular structure MLT is for conveying a fluid for a motor vehicle selected from the group consisting of air, oil, water, urea solution, glycol coolant, or fuel.

3. Multilayer tubular structure MLT according to claim 2, wherein said fuel is selected from the group consisting of gasoline, diesel, or hydrogen.

4. Multilayer tubular structure MLT according to claim 3, wherein said gasoline is selected from the group consisting of alcoholized gasoline and bio-gasoline.

5. Multilayer tubular structure MLT according to claim 3, wherein said diesel is selected from the group consisting of bio-diesel.

6. Multilayer tubular structure MLT according to claim 1, wherein said at least one layer (1) comprises a composition comprising at least 50% of recycled material from a multilayer tube, said multilayer tube having conveyed a fluid for a motor vehicle selected from the group consisting of air, oil, water, urea solution, glycol coolant, or fuel.

7. Multilayer tubular structure MLT according to claim 6, wherein said fuel is selected from the group consisting of gasoline, diesel, or hydrogen.

8. Multilayer tubular structure MLT according to claim 7, wherein said gasoline is selected from the group consisting of alcoholized gasoline and bio-gasoline.

9. Multilayer tubular structure MLT according to claim 7, wherein said diesel is selected from the group consisting of bio-diesel.

10. Multilayer tubular structure MLT according to claim 1, wherein said layer (1) is located between layer (2) and layer (2').

11. Multilayer tubular structure MLT according to one of claims 1 to 10, wherein layer (2') is the layer in contact with the fluid.

12. Multilayer tubular structure MLT according to one of claims 1 to 10, wherein layer (2') is as defined for layer (2).

13. Multilayer tubular structure MLT according to claim 12, wherein layers (2) and (2') are identical. ​ ​ ​ ​ ​ ​ ​ 14. Multilayer tubular structure MLT according to one of claims 1 to 10, wherein at least one adhesive layer (3) is present, said layer (3) being located between layer (2) and layer (1) and / or between layer (1) and layer (2').

15. Multilayer tubular structure MLT according to one of claims 1 to 10, wherein said layer (1) represents at least 10% of the total thickness of said multilayer tubular structure MLT.

16. Multilayer tubular structure MLT according to claim 15, wherein said layer (1) represents at least 30% of the total thickness of said multilayer tubular structure MLT.

17. Multilayer tubular structure MLT according to claim 16, wherein said layer (1) represents at least 50% of the total thickness of said multilayer tubular structure MLT.

18. Multilayer tubular structure MLT according to one of claims 1 to 10, wherein said layer (1) comprises a composition comprising: 0 to 45% by weight of at least one impact modifier, 0 to 20% by weight of at least one plasticizer, 0 to 2% by weight of at least one additive, the sum of the constituents being equal to 100%. at least 50% by weight of at least one semi-crystalline aliphatic polyamide denoted C having an average number of carbon atoms per nitrogen atom denoted C C between 6 and 18; 0 to 25 % by weight of at least one compound B and having the formula C B a semi-crystalline aliphatic polyamide having an average number of carbon atoms per nitrogen atom of Cc-1; 0 to 25 % by weight of a semi-crystalline aliphatic polyamide denoted A having an average number of carbon atoms per nitrogen atom denoted C A = C B – 1; and 0 to 25 % by weight of a semi-crystalline aliphatic polyamide denoted A having an average number of carbon atoms per nitrogen atom denoted C 19. Multilayer tubular structure MLT according to claim 18, wherein said layer (1) comprises a composition comprising: 50% to 97% by weight of at least one semi-crystalline aliphatic polyamide noted C.

23. Multilayer tubular structure MLT according to claim 18, wherein said layer (1) comprises a composition comprising: 3 to 45% by weight of at least one impact modifier.

24. Multilayer tubular structure MLT according to claim 1, wherein said composition of layer (1) is devoid of plasticizer and / or impact modifier, and said recycled material is from a multilayer pipe selected from the group consisting of: a multilayer pipe that has been shredded and recompounded, and a multilayer pipe that has been shredded, recompounded and reformulated.

25. Multilayer tubular structure MLT according to claim 1, wherein said composition of layer (1) comprises at least one compound selected from the group consisting of: a plasticizer, an impact modifier and an additive, and said recycled material is from a multilayer pipe selected from the group consisting of: a multilayer pipe that has been shredded, then recompounded and reformulated.

26. Multilayer tubular structure MLT according to one of claims 1 to 10, wherein the fluid transported by said multilayer pipe is the same as the fluid transported by said multilayer tubular structure MLT.

20. The multi-layered tubular structure MLT according to claim 18, wherein the at least one semi-crystalline aliphatic polyamide denoted C has an average number of carbon atoms per nitrogen atom denoted C C of from 8 to 12.​ 21. The multilayer tubular structure MLT according to claim 18, wherein said layer (1) comprises a composition comprising from 0 to 25% by weight of at least one semi-crystalline aliphatic polyamide having an average number of carbon atoms per nitrogen atom, noted Cc, of between 2 and 4. B = Cc – 2.

22. The multi-layered tubular structure MLT according to claim 18, wherein the semi- crystalline aliphatic polyamide denoted A has an average number of carbon atoms per nitrogen atom denoted C A = C B - 2.

27. Multilayer tubular structure MLT according to one of claims 1 to 10, wherein the fluid transported by said multilayer pipe is different from the fluid transported by said multilayer tubular structure.

28. Multilayer tubular structure MLT according to claim 1, wherein layer (2) comprises a composition comprising: 3 to 45% by weight of at least one impact modifier, 0 to 20% by weight of at least one plasticizer, 0 to 2% by weight of at least one additive, 0 to 35% of at least one antistatic filler, the sum of the constituents being equal to 100%.

29. Multilayer tubular structure MLT according to claim 28, wherein layer (2) comprises a composition comprising: 50% to 97% by weight of at least one semi-crystalline aliphatic polyamide noted D. ​ ​ ​ at least 50% by weight of at least one semi-crystalline aliphatic polyamide denoted D having an average number of carbon atoms per nitrogen atom denoted C D between 6 and 18; 0 to 50 % by weight of at least one compound E and having the formula C E = C D a semi-crystalline aliphatic polyamide having an average number of carbon atoms per nitrogen atom of -1 ; 0 to 50 % by weight of a semi-crystalline aliphatic polyamide denoted F having an average number of carbon atoms per nitrogen atom denoted C F = C E – 1; and 0 to 50 % by weight of a semi-crystalline aliphatic polyamide denoted F having an average number of carbon atoms per nitrogen atom denoted C ​ ​ ​ ​ ​ ​ 30. Multilayer tubular structure MLT according to claim 29, wherein layer (2) comprises a composition comprising from 50 to 95 % by weight of at least one semi-crystalline aliphatic polyamide designated D.

31. The multi-layered tubular structure MLT according to claim 28, wherein the at least one semi-crystalline aliphatic polyamide noted D has an average number of carbon atoms per nitrogen atom noted C of from 9 to 15. D .

32. The multilayer tubular structure MLT according to claim 28, wherein layer (2) comprises a composition comprising from 0 to 50% by weight of at least one semi-crystalline aliphatic polyamide having an average number of carbon atoms per nitrogen atom denoted as C E = C D - 2.

33. The multi-layered tubular structure MLT according to claim 28, wherein the semi- crystalline aliphatic polyamide denoted F has an average number of carbon atoms per nitrogen atom denoted C F = C E - 2.

34. Multilayer tubular structure MLT according to claim 28, wherein layer (2) comprises a composition comprising from 5 to 20 % by weight of at least one impact modifier.

35. The multi-layer tubular structure MLT according to claim 28, wherein said composition of said layer (1) lacks the polyamides designated A and B, and said composition of said layer (2) comprises a polyamide selected from the polyamides designated E, F and mixtures thereof, wherein the polyamide designated B has an average number of carbon atoms per nitrogen atom, designated C B = Cc - 1, and the polyamide designated A has an average number of carbon atoms per nitrogen atom, designated C A = C B - 1, and C C is between 6 and 18.

36. The multi-layer tubular structure MLT according to claim 28, wherein said composition of said layer (1) comprises a polyamide selected from the group consisting of polyamides designated A, B and mixtures thereof, and said composition of said layer (2) lacks polyamides designated E and F, wherein the polyamide designated B has an average number of carbon atoms per nitrogen atom designated C B = Cc - 1, and the polyamide designated A has an average number of carbon atoms per nitrogen atom designated C A = C B - 1, and C C is between 6 and 18.

37. Multilayer tubular structure MLT according to one of claims 28 to 36, wherein the polyamide of layer (1) is from a recycled multilayer pipe.

38. Multilayer tubular structure MLT according to any one of claims 1 to 10, wherein the main aliphatic semi-crystalline polyamide of layer (1) has a Tm ≤ 225 °C determined by DSC according to ISO 11357-3:2013 with a heating rate of 20 K / min.

39. Multilayer tubular structure MLT according to claim 38, wherein the main aliphatic semi-crystalline polyamide of layer (1) has a Tm ≤ 200 °C.

40. Multilayer tubular structure MLT according to one of claims 1 to 10, wherein the main aliphatic semi-crystalline polyamide of layer (1) has a crystallization enthalpy ≥ 25 J / g determined by DSC according to ISO 11357-3:2013 with a heating rate of 20 K / min.

41. Multilayer tubular structure MLT according to claim 40, wherein the main aliphatic semi-crystalline polyamide of layer (1) has a crystallization enthalpy ≥ 40 J / g.

42. Multilayer tubular structure MLT according to claim 41, wherein the main aliphatic semi-crystalline polyamide of layer (1) has a crystallization enthalpy ≥ 45 J / g.

43. Multilayer tubular structure MLT according to one of claims 1 to 10, wherein the MLT comprises the following three structural layers: (2) / / (1) / / (2).

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