Process for decontaminating and recycling a polyamide by continuous degassing in the molten state

Abstract

The present invention relates to a process for recycling a polyamide, said polyamide originating from at least one product consisting of one or more elements comprising an initial composition C1 comprising a polyamide, pollutants from the use of said product, and one or more volatile and non-volatile constituent(s) originally present in said product before its use, the initial proportion of said pollutants being from 0.1 to 20% by weight relative to the total weight of said composition, characterized in that it comprises the following steps: a) Optionally pre-treatment of said product, b) Optionally shaping of said untreated product or of said element separated in step a), c) introduction of said untreated product and optionally shaped in step b) or of said element separated from step a) and optionally shaped in step b) into a meltable system,at a temperature above the Tf of said polyamide if it is semi-crystalline or above the Tg of said polyamide if it is amorphous, d) introduction of said molten product obtained in step c) into a system capable of continuously conveying a polymer and having a degassing surface, e) distribution in the form of a thin film on the walls of said system by means of a rotor with continuous degassing of said molten product from step d) to reduce or eliminate said pollutants and said volatile constituent(s), f) obtaining a final composition C2 of molten polyamide and subsequently forming it into powder, ground material, granules or a new extruded part, said final formed composition having a proportion by weight of said pollutants lower than the initial proportion present in said initial composition C1.

Description

Title of the invention: Process for decontaminating and recycling a polyamide by continuous degassing in the molten state Technical field

[0001] The present patent application relates to a process for decontaminating and recycling a polyamide (PA) by continuous degassing in the molten state, as well as its use for the preparation of articles obtained by extrusion or injection. Prior art

[0002] Polyamides are used, among other things, to manufacture articles for a wide variety of applications such as automobiles, offshore or onshore oil exploitation, electricity, household appliances, textiles, sports and leisure, food packaging, medical packaging, etc.

[0003] There are two types of waste: post-industrial waste and post-consumer waste.

[0004] When using these polyamides to manufacture said articles, for example by extrusion, by extrusion-blow molding, by rotational molding or by injection or by 3D printing, a significant quantity of the volume of polyamide used is lost, in particular at the start of production, at the end of production as well as during production, in the event of a production problem, with the consequence of obtaining scrap, debris, waste, residue, leftovers, trimmings. This corresponds to post-industrial waste.

[0005] After implementation of these polyamides and use of said articles obtained in said applications, the circular economy requires limiting the production of waste, the depletion of the planet's resources and the environmental impact.

[0006] It therefore becomes necessary to be able to recycle these used polyamides.

[0007] This corresponds to post-consumer waste.

[0008] Thus, each year, several million motor vehicles become unusable throughout the world.

[0009] A motor vehicle contains a large number of pipes, in particular pipes intended for the transport of fluids such as air, oil (for example for cooling the automatic gearbox "TOC, Transmission Oil Cooler), water, a urea solution, a glycol-based coolant, a fuel such as gasoline, in particular bio-gasoline or diesel, in particular bio-diesel, or hydrogen.

[0010] These pipes may be single-layer and / or multi-layer tubular structures, in particular based on polyamide(s) which may contain other constituents such as as plasticizers, impact modifiers, fillers, stabilizers, additives, monomers and oligomers.

[0011] In addition, after use, pipes intended for the transport of fluids may become polluted by the transported fluid.

[0012] A fuel transport pipe, for example a polyamide pipe which contains a plasticizer, has lost most of its plasticizer when it reaches the end of its life and the polyamide constituting it initially present is depolymerized and / or degraded and has lost most of its stabilizers, which prevents its safe reuse.

[0013] When the motor vehicle is out of use, the various pipes present in it are generally very or too degraded to be able to be reused as, in the form of a tube, without risk or without this leading to excessively degraded usage properties.

[0014] Indeed, the tubes, particularly under the engine hood, are placed in a severe thermo-oxidative environment due to the heat released by the engine which can typically reach 150°C and the presence of air and therefore oxygen. Each increase in temperature of 10°C typically results in a halving of the service life of the tubes as well as the degradation of certain additives of said tubes such as stabilizers.

[0015] Furthermore, a pipe used to transport, for example, fuel is polluted by said fuel as it is used and at least the layer in contact with said fuel has absorbed part of the transported fuel.

[0016] The same applies to an engine cooling pipe, air conditioning pipe, or brake pipe.

[0017] The polyamides (PA) from these pipes cannot be used as they are and cannot be used after simple grinding because of the pollutants they contain.

[0018] Until recently, used automotive hoses were not reused and were often incinerated, but this contributed to global warming, the reduction of which is becoming one of the major challenges of the 21st century.

[0019] European Directive 2000 / 53 / EC relating to end-of-life vehicles has set a reuse and recovery rate of 95% by weight per vehicle from 2015.

[0020] There should therefore only remain 5% of ultimate waste, that is to say waste which is not capable of being treated under the technical and economic conditions of the moment and which will be incinerated or evacuated to specific storage centers.

[0021] This is one of the reasons why several car manufacturers have the more or less long-term objective of recycling 100% of the vehicles they produce in order to achieve an environmental impact equal to zero.

[0022] Furthermore, in the exploitation of oil or gas deposits under the sea (off-shore) or on land (on-shore), it is necessary to use flexible pipes to connect the various devices around the platform. These pipes must withstand hot oil, gas, water and mixtures of at least two of these products for periods of up to 20 years. These pipes are generally made up of a non-watertight inner metallic layer formed by a profiled metal strip wound in a helix such as a stapled strip and which gives the shape to the pipe, then on this layer a polymer is extruded to provide the seal and finally other protective and reinforcing layers are added such as sheets of metallic fibers and rubbers.

[0023] Long-chain polyamides have been used for years for the exploitation of oil or gas deposits, underwater or on land.

[0024] Several tens to hundreds of tons of long-chain polyamides from oil or gas field exploitation pipes, underwater or on land (respectively offshore or on shore pipes) will have to be recycled in the coming years due to the fact that they have reached the end of their life.

[0025] Polyamides (PA) from oil or gas field exploitation pipes, underwater or on land, cannot be used as is and cannot be used after simple grinding because of the pollutants from the extracted oil or gas that they contain.

[0026] They must therefore first be ground so that they can subsequently be transformed into a part having a different shape for a different application.

[0027] After grinding, the polyamide to be recycled must also be washed and / or compounded in order to extract a large majority of pollutants (with solvents, in melt, under vacuum, etc.). However, the extraction is not necessarily complete.

[0028] Without this washing and / or compounding step, the manufactured parts exudate. This exudate can be toxic to the user and can generate a greasy appearance on the parts.

[0029] There is therefore a need to be able to recycle and decontaminate these polyamides after use in their various applications.

[0030] The invention therefore aims to propose a method for recycling a polyamide, said polyamide originating from at least one product consisting of one or more elements comprising an initial composition Cl comprising a polyamide, pollutants originating from the use of said product and one or more volatile and non-volatile constituent(s) originally present in said product before its use,

[0031] said product being obtained during or after the implementation of said composition by extrusion, by extrusion-blow molding, by rotational molding, by injection or by 3D printing,

[0032] the initial proportion of said pollutants being between 0.1 and 20% by weight per relative to the total weight of said composition, in particular from 0.5 to 15%, in particular from 0.5 to 10%, more particularly from 0.5 to 5%.

[0033] characterized in that it comprises the following steps:

[0034] a) Optionally pre-treatment of said product to separate the element comprising said composition from other elements not recyclable with said process and present in said product,

[0035] b) Optionally shaping said untreated product or said separate element in step a) so as to be able to be introduced into a system capable of melting and transporting a polymer continuously,

[0036] c) introduction of said untreated product and optionally shaped in step b) or of said separate element from step a) and optionally shaped in step b) into a system capable of melting and transporting a polymer continuously, in particular an extruder, at a temperature higher than the Tf of said polyamide if it is semi-crystalline or higher than the Tg of said polyamide if it is amorphous,

[0037] d) introducing said molten product obtained in step c) into a system capable of continuously transporting a polymer and having a degassing surface, in particular under reduced pressure, in particular said system is a thin-film evaporator,

[0038] e) distribution in the form of a thin film on the walls of said system by means of a rotor with continuous degassing, in particular under reduced pressure, of said molten product of step d) to reduce or eliminate said pollutants and said one or more volatile constituent(s),

[0039] f) obtaining a final composition C2 of molten polyamide and then putting it in the form of powder, ground material, granules or a new extruded part, said final shaped composition having a proportion by weight of said pollutants lower than the initial proportion present in said initial composition Cl, in particular <2%, in particular <1%, in particular <0.5% by weight relative to the total weight of composition C2.

[0040] The inventors have therefore unexpectedly found that the introduction of a product obtained during or after the processing of a polyamide by extrusion, by extrusion-blow molding, by rotational molding, by injection or by 3D printing, after use of said product, or the introduction of an element separated beforehand from said product, after use of said product, into a system capable of continuously transporting a polymer and having a degassing surface, after passage through a system capable of melting, in particular an extruder, then distribution in the form of a thin film on the walls of said system by means of a rotor with degassing, in particular under reduced pressure, continuously in the molten state of said product or said polyamide made it possible to obtain a final composition C2 of molten polyamide and put into the form of powder, ground material, granules or a new extruded part, with a proportion by weight of pollutants in the final composition C2 lower than the initial proportion present in said initial composition Cl, in particular <2%, in particular <1%, more particularly <0.5%, relative to the total weight of the composition C2.

[0041] The invention therefore makes it possible firstly to limit or remove the pollutants from said initial composition Cl of said element of said product and comprising said polyamide while maintaining a viscosity in the molten state of the polyamide obtained after recycling compatible with injection or extrusion applications.

[0042] The melt viscosity of said polyamide can be measured in plane-plane rheology under 1 Hz and 2% deformation, at a temperature dependent on the Tf of said polymer, for example at a temperature between Tf + 10°C and Tf + 100°C.

[0043] The invention secondly makes it possible to remove said volatile constituent(s) at the same time.

[0044] The expression "product consisting of one or more elements and obtained during or after the processing of said polyamide by extrusion, extrusion blow molding, rotational injection molding or 3D printing" designates a product obtained after the processing of said polyamide by extrusion, extrusion blow molding, rotational injection molding or 3D printing and after its use or having reached the end of its life. These are therefore post-consumer waste.

[0045] The product is therefore made up of one or more elements depending on its use and at least one of the elements containing a polyamide will be or is in contact with the pollutants during the use of said product.

[0046] In one embodiment, two elements containing a polyamide will be or are in contact with the pollutants during the use of said product.

[0047] When two elements are in contact with said pollutant, the second element which does not transport said fluid is in contact with said pollutant by migration of said pollutant from the first element which transports the fluid to the second element. It goes without saying that the two elements adhere to each other.

[0048] In another embodiment, a single element containing a polyamide will be or is in contact with the pollutants during the use of said product.

[0049] One of the advantages of the invention is therefore to be able to recycle a polyamide constituting an element of a product after production of said product and after its use and to be able to eliminate or at least reduce the proportion of pollutants present in said product and in particular in said polyamide.

[0050] Another advantage of the invention is to be able to remove during recycling one or more volatile constituent(s) initially present in said initial polyamide composition Cl as well as the pollutants after use and to be able thus on the one hand to recover said polyamide substantially free of said constituent(s) volatile(s) and said pollutants for another use.

[0051] The proportion of pollutants depends on the use (post-consumer waste) of the product.

[0052] When the product is used (post-consumer waste), the proportion of pollutants depends on the type of use.

[0053] The proportion of pollutants in said final composition C2 can be determined according to an ATG protocol according to the ISO 11358:2022 standard.

[0054] It was determined using an ATG TA Instrument TGA550 device under vacuum at 5 hPa with an isothermal measurement with the Equilibrate function for 1 hour at 300°C.

[0055] The nature of the pollutants can be determined by coupling the ATG to an infrared spectroscopy or mass spectroscopy device.

[0056] The term "pollutant" designates any component or ingredient which, upon contact with the polyamide or a product containing it, during its use, contaminates said polyamide or product containing it, thus preventing its recycling as is.

[0057] Throughout the description, all percentages are indicated by weight unless otherwise specified.

[0058] In one embodiment, the pollutants are selected from oil, water, a urea solution, a coolant, in particular glycol-based, a fuel such as gasoline, in particular alcoholic gasoline, bio-gasoline or diesel, in particular bio-diesel, hydrogen, oil and gas and the extraction additives of these compounds.

[0059] In a first variant of this embodiment, the pollutants are oil and gas and the extraction additives of these compounds.

[0060] In a second variant of this embodiment, the pollutants are chosen from oil, water, a urea solution, a glycol-based coolant, a fuel such as gasoline, in particular alcoholic gasoline, biogasoline or diesel, in particular biodiesel, hydrogen.

[0061] In a third variant of this embodiment, the pollutants are chosen from oil, water, a urea solution, a glycol-based coolant, a fuel such as gasoline, in particular alcoholic gasoline, bio-gasoline or diesel, in particular bio-diesel.

[0062] In a fourth variant of this embodiment, the pollutants are chosen from a fuel such as gasoline, in particular alcoholic gasoline, bio-gasoline or diesel, in particular bio-diesel.

[0063] In a fifth variant of this embodiment, the pollutants are hydrogen.

[0064] The proportion of said volatile and non-volatile constituent(s) in said initial composition Cl constituting said element of said product before its use depends on the proportion introduced during its preparation of said initial composition Cl.

[0065] In one embodiment, said product is chosen from a single-layer or multi-layer structure obtained by extrusion, extrusion-blow molding, rotational injection molding or by 3D printing, a production start-up product of said structure, an end-of-production product of said structure and a production scrap of said structure. When the product is a single-layer structure, said single-layer structure therefore corresponds to a single element which comprises said initial polyamide composition Cl and which has been in contact with said pollutant by absorption of the pollutant by said element which transports said fluid.

[0066] When the product is a multilayer structure, said multilayer structure is therefore made up of at least two elements and at least one of the elements comprises said initial polyamide composition Cl and which has been in contact with said pollutant.

[0067] When more than one element has been in contact with said pollutant, the second element which does not transport said fluid has been in contact with said pollutant by migration of said pollutant from the first element which transports the fluid to the second element. It goes without saying that the two elements adhere to each other.

[0068] In one embodiment, only one element comprises said initial polyamide composition Cl and said element has been in contact with said pollutant and has transported or stored said fluid.

[0069] Extrusion is a (thermo)mechanical manufacturing process by which a compressed material is forced to pass through a die having the section of the part to be obtained. An extrudate, a long product (tube, pipe, profile, textile fiber) and / or a flat product (plate, sheet, film) is formed continuously.

[0070] Extrusion blow molding is a process for shaping thermopolymer materials moplastics which is used to manufacture hollow bodies of variable capacity (from a few cm3 to a few m3): bottles, flasks, cans, drums, tanks, etc. This process consists of combining the extrusion technique with that of blowing.

[0071] Rotomolding, or rotational molding, is a process of shaping, in particular hollow objects, by molding plastic materials in a mold in order to reproduce the internal shape of this mold.

[0072] Thermoplastic injection consists of injecting a molten polymer (thermoplastic material) under high pressure into a mold, using an injection press.

[0073] 3D printing or additive manufacturing brings together manufacturing processes that allow the creation of volume parts by adding material in successive layers.

[0074] The term “structure” also refers to any shape, system or construction that can be obtained by extrusion, extrusion blow molding, rotational molding or injection.

[0075] In one embodiment, said structure is selected from a pipe, a granule, a film, a sheet, a sheath, a reservoir, a hollow body, and mixtures thereof.

[0076] In a first variant of this embodiment, said structure is a structure obtained by extrusion.

[0077] In a first embodiment of this first variant, said structure is a single-layer or multi-layer structure, in particular multi-layer.

[0078] In this first embodiment of this first variant, said structure may be a fluid transport pipe for an automobile.

[0079] Said transported fluids are for example air, oil (for example for cooling the automatic gearbox "TOC, Transmission Oil Cooler), water, a urea solution, a coolant, in particular glycol-based, a fuel such as gasoline, in particular bio-gasoline or diesel, in particular bio-diesel, or hydrogen.

[0080] In a second embodiment of this first variant, said structure is a pipe for exploiting an oil or gas deposit, underwater or on land.

[0081] Advantageously, said structure is a pipe for exploiting an oil or gas deposit, under the sea.

[0082] In a second variant of this embodiment, said structure is a structure obtained by injection.

[0083] In a first embodiment of this second variant, said structure may be an article in the field of sport, industry, electronics and optics.

[0084] In a third variant of this embodiment, said structure is a structure obtained by rotational molding.

[0085] In a first embodiment of this third variant, said structure may be a reservoir or a hollow body.

[0086] In a fourth variant of this embodiment, said structure is a structure obtained by extrusion-blowing.

[0087] In a first embodiment of this fourth variant, said structure may be a reservoir or a hollow body. Regarding polyamide to be recycled

[0088] The nomenclature used to define polyamides is described in the ISO 1874-1:2011 standard

[0089] “Plastics - Polyamide (PA) materials for molding and extrusion - Part 1: De signature”, particularly on page 3 (tables 1 and 2) and is well known to those skilled in the art.

[0090] The polyamide may be a homopolyamide or a copolyamide or a mixture thereof.

[0091] The polyamide has in particular an average number of carbon atoms per nitrogen atom greater than or equal to 6.5, in particular greater than or equal to 8, in particular greater than or equal to 9, more particularly greater than or equal to 10, even more particularly greater than or equal to 11.

[0092] The number-average molecular mass Mn of said polyamide is preferably greater than or equal to 10,000 g / mol, in particular from 10,000 to 85,000 g / mol, in particular from 10,000 to 60,000 g / mol, in particular from 10,000 to 50,000 g / mol, more particularly from 10,000 to 40,000 g / mol, even more particularly from 10,000 to 30,000 g / mol. The Mn is measured according to the following protocol:

[0093] the polyamide is solubilized in hexafluoroisoproponol stabilized with 0.05 M potassium trifluoroacetate for 24 h at room temperature (20°C) at a concentration of 2 g / L. The solution obtained is then filtered through a PTFE membrane with a porosity of 0.2 pm, then injected at a flow rate of 1 mL / min, into a liquid chromatography system equipped with a set of PFG columns from Polymer Standards Service consisting of a pre-column with dimensions of 50 x 8 mm, a 1000 Å column with dimensions of 300 x 8 mm and a particle size of 7 pm, and a 100 Å column with dimensions of 300 x 8 mm and a particle size of 7 pm. Molar masses are measured by the refractive index and are expressed in PMMA equivalents, used as a calibration standard, then converted to g / mol.

[0094] The polyamide can be semi-crystalline or amorphous.

[0095] A semi-crystalline polyamide, within the meaning of the invention, designates a polyamide which has a glass transition temperature (Tg) and a melting temperature (Tf) determined respectively according to the ISO 11357-2 and 3:2013 standard, and an enthalpy of crystallization during the cooling step at a rate of 20K / min in DSC measured according to the ISO 11357-3 standard

[0096] of 2013 greater than 30 J / g, preferably greater than 35 J / g.

[0097] In one embodiment, the polyamide is semi-crystalline, in particular aliphatic. semi-crystalline.

[0098] In one embodiment, the semi-crystalline aliphatic polyamide is linear.

[0099] In one embodiment, the semi-crystalline aliphatic polyamide is a homo- polyamide, in particular a semi-crystalline linear aliphatic homopolyamide.

[0100] In one embodiment, said semi-crystalline aliphatic polyamide, in particular semi-crystalline linear aliphatic homopolyamide, is excluding polyamide 6 (PA6).

[0101] Said semi-crystalline polyamide can be obtained by polycondensation:

[0102] of at least one amino acid in C6 to C18, preferably in C10 to C18, more preferably in C10 to C12, or

[0103] of at least one C6 to C18 lactam, preferably C10 to C18, more preferably- tially in Cio to Ci2, or

[0104] of at least one aliphatic diamine Ca in C4-C36, preferably C5-Ci8, preferably C5-C12, more preferably C10-Ci2, with at least one aliphatic dicarboxylic acid Cb in C4-C36, preferably C6-Ci8, preferably C6-C 12, more preferably Cio-Ci2>;

[0105] When said at least one aliphatic semi-crystalline polyamide is obtained from the polycondensation of at least one lactam, said at least one lactam may be chosen from a C6 to C[8 lactam, preferably a C10 to C[8 lactam, more preferably a C10 to C12 lactam. A C6 to C12 lactam is in particular caprolactam, decanolactam, undecanolactam, and lauryllactam.

[0106] When said at least one aliphatic semi-crystalline polyamide is obtained from the polycondensation of at least one lactam, it can therefore comprise a single lactam or several lactams.

[0107] Advantageously, said at least one aliphatic semi-crystalline polyamide is obtained from the polycondensation of a single lactam and said lactam is chosen from lauryllactam and undecanolactam, advantageously lauryllactam.

[0108] When said at least one aliphatic semi-crystalline polyamide is obtained from the polycondensation of at least one amino acid, said at least one amino acid may be chosen from a C6 to C18 amino acid, preferably a C10 to C18 amino acid, more preferably a C10 to C12 amino acid.

[0109] A C6 to C12 amino acid is in particular 6-aminohexanoic acid, 9-aminononanoic acid, 10-aminodecanoic acid, 10-aminoundecanoic acid, 12-aminododecanoic acid and 11-aminoundecanoic acid as well as its derivatives, in particular N-heptyl-11-aminoundecanoic acid.

[0110] When said at least one aliphatic semi-crystalline polyamide is obtained from the polycondensation of at least one amino acid, it can therefore comprise a single amino acid or several amino acids.

[0111] Advantageously, said aliphatic semi-crystalline polyamide is obtained from the polycondensation of a single amino acid and said amino acid is chosen from 11-aminoundecanoic acid and 12-aminododecanoic acid, advantageously 11-aminoundecanoic acid.

[0112] When said at least one aliphatic semi-crystalline polyamide is obtained from the polycondensation of at least one C4-C36, preferably C5-C18, preferably C5-C12, more preferably C10-C12, Ca diamine with at least one C4-C36, preferably C6-C18, preferably C6-C12, more preferably C10-C12, Cb diacid then said at least one Ca diamine is an aliphatic diamine and said at least one Cb diacid is an aliphatic diacid.

[0113] The diamine may be linear or branched. Advantageously, it is linear.

[0114] Said at least one C4-C36 diamine Ca may in particular be chosen from 1,4-butanediamine, 1,5-pentamethylenediamine, 1,6-hexamethylenediamine, 1,7-heptamethylenediamine, 1,8-octamethylenediamine, 1,9-nonamethylenediamine, 1,10-decamethylenediamine, 1,11-undecamethylenediamine, 1,12-dodecamethylenediamine, 1,13-tridecamethylenediamine, 1,14-tetradecamethylenediamine, 1,16-hexadecamethylenediamine and 1,18-octadecamethylenediamine, octadecenediamine, eicosanediamine, docosanediamine and diamines obtained from fatty acids.

[0115] Advantageously, said at least one diamine Ca is C5-Ci8 and is chosen from 1,5-pentamethylenediamine, 1,6-hexamethylenediamine, 1,7-heptamethylenediamine, 1,8-octamethylenediamine, 1,9-nonamethylenediamine, 1,10-decamethylenediamine, 1,11-undecamethylenediamine, 1,12-dodecamethylenediamine, 1,13-tridecamethylenediamine, 1,14-tetradecamethylenediamine, 1,16-hexadecamethylenediamine and 1,18-octadecamethylenediamine.

[0116] Advantageously, said at least one diamine Ca in C5 to C12, is in particular chosen from 1,5-pentamethylenediamine, 1,6-hexamethylenediamine, 1,7-heptamethylenediamine, 1,8-octamethylenediamine, 1,9-nonamethylenediamine, 1,10-decamethylenediamine, 1,11-undecamethylenediamine, 1,12-dodecamethylenediamine.

[0117] Advantageously, the diamine Ca used is C10 to C12, in particular chosen from 1,10-decamethylenediamine, 1,11-undecamethylenediamine, 1,12-dodecamethylenediamine.

[0118] Said at least one Cb dicarboxylic acid in C4 to C36 may be chosen from succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, brassylic acid, tetradecanedioic acid, pentadecanedioic acid, hexadecanedioic acid, octadecanedioic acid, and diacids obtained from fatty acids.

[0119] The diacid may be linear or branched. Advantageously, it is linear.

[0120] Advantageously, said at least one dicarboxylic acid Cb is C6 to C[8 and is chosen from adipic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, brassylic acid, tetradecanedioic acid, pentadecanedioic acid, hexadecanedioic acid, octadecanedioic acid.

[0121] Advantageously, said at least one dicarboxylic acid Cb is C6 to C[2 and is chosen from adipic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid.

[0122] Advantageously, said at least one dicarboxylic acid Cb is C10 to C12 and is chosen from sebacic acid, undecanedioic acid, dodecanedioic acid.

[0123] When said aliphatic semi-crystalline polyamide is obtained from the polycondensation of at least one diamine Ca with at least one dicarboxylic acid Cb, it can therefore comprise a single diamine or several diamines and a single dicarboxylic acid or several dicarboxylic acids.

[0124] Advantageously, said aliphatic semi-crystalline polyamide is obtained from the polycondensation of a single diamine Ca with a single dicarboxylic acid Cb.

[0125] In particular, the semi-crystalline polyamide is chosen from:

[0126] polyamide 11 (PA11), polyamide 12 (PA12), polyamide 516 (PA516), polyamide 610 (PA610), polyamide 612 (PA612), polyamide 1010 (PA1010), polyamide 1012 (PA1012), polyamide 1212 (PA1212), polyamide 1014 (PA1014), polyamide 1214 (PA1214), or a mixture thereof or a copolyamide thereof, in particular PA11 and PA 12, in particular PAU.

[0127] More particularly, it is chosen from polyamide 11 (PA11), polyamide 12 (PA12), polyamide 612 (PA612), polyamide 1010 (PA1010), polyamide 1012 (PA1012), polyamide 1212 (PA1212), polyamide 1014 (PA1014), polyamide 1214 (PA 1214), or a mixture thereof or a copolyamide thereof, in particular PAU and PA 12, in particular PAU.

[0128] Even more particularly, it is chosen from:

[0129] polyamide 11 (PAU), polyamide 12 (PA12), polyamide 1010 (PA1010), polyamide 1012 (PA1012), polyamide 1212 (PA1212), polyamide 1014 (PA1014), polyamide 1214 (PA1214), or a mixture thereof or a copolyamide thereof, in particular PA11 and PA 12, in particular PAU.

[0130] In particular, it is chosen from:

[0131] polyamide 11 (PAU), polyamide 12 (PA12), polyamide 1012 (PA1012), polyamide 1212 (PA1212), polyamide 1014 (PA1014), polyamide 1214 (PA1214), or a mixture thereof or a copolyamide thereof, in particular PA11 and PA 12, in particular PAU.

[0132] An amorphous polyamide within the meaning of the invention designates a polyamide which has only one glass transition temperature (no melting temperature (Tf)), or a very slightly crystalline polyamide having a glass transition temperature and a melting point such that the crystallization enthalpy during the cooling step at a rate of 20K / min measured according to the ISO 11357-3:2013 standard is less than 30 J / g, in particular less than 20 J / g, preferably less than 15 J / g.

[0133] When said at least one amorphous polyamide is a homopolyamide of formula XY or a copolyamide of formula A / XY, then XY is a repeating unit obtained by polycondensation of at least one cycloaliphatic diamine (X) and at least one acid aliphatic dicarboxylic acid (Y) in C4-C36, preferably C6-C18, preferably C6-C12, more preferably C10-C12OR of at least one aromatic dicarboxylic acid (Y) and A is a repeating unit obtained by polycondensation of at least one amino acid in C6 to C[8, preferably in C10 to C[8, more preferably in C10 to C12, or

[0134] of at least one C6 to C[8] lactam, preferably C10 to C[8] lactam, more preferably C10 to C12 lactam, or

[0135] of at least one diamine Ca in C4-C36, preferably C5-Ci8, preferably C5-C12, more preferably C10-C12, with at least one dicarboxylic acid Cb in C 4-C36, preferably C6-Ci8, preferably C6-Ci2, more preferably Cio -C12.

[0136] The cycloaliphatic diamine (X) may be chosen from bis(3,5-dialkyl-4-aminocyclohexyl)methane, bis(3,5-dialkyl-4-aminocyclohexyl)ethane, bis(3,5-dialkyl-4-aminocyclohexyl)propane, bis(3,5-dialkyl-4-aminocyclohexyl)butane, bis-(3-methyl-4-aminocyclohexyl)methane or 3,3'-dimethyl-4,4'-diamino-dicyclohexylmethane commonly called (BMACM) or (MACM) (and noted B hereinafter), bis(p-aminocyclohexyl)methane commonly called (PACM) (and noted P hereinafter), in particular Dicykan®, isopropylidenedi(cyclohexylamine) commonly called (PACP), isophorone-diamine (denoted IPD hereinafter) and 2,6-bis(amino methyl)norbornane commonly referred to as (BAMN) and bis(aminomethyl)cyclohexane (BAC), in particular 1,3-BAC or , in particular 1,4-BAC.

[0137] Advantageously, it is chosen from bis-(3-methyl-4-aminocyclohexyl)-methane or 3,3'-dimethyl-4,4'-diamino-dicyclohexyl-methane commonly called (BMACM) or (MACM) (and noted B below), bis(p-aminocyclohexyl)-methane commonly called (PACM) (and noted P below) and bis(aminomethyl)cyclohexane (BAC), in particular 1,3-BAC or , in particular 1,4-BAC.

[0138] A, Ca and Cb are as defined above.

[0139] When (Y) is at least one C4-C36, preferably C6-C18, preferably C6-C12, more preferably C10-C12 aliphatic dicarboxylic acid, it is as defined for Cb.

[0140] When (Y) is at least one aromatic dicarboxylic acid (Y), it is advantageously chosen from terephthalic acid (denoted T), isophthalic acid (denoted I) and 2,6-naphthalene dicarboxylic acid (denoted N) or their mixtures, in particular it is chosen from terephthalic acid (denoted T), isophthalic acid (denoted I) or their mixtures.

[0141] In a first variant, said at least one amorphous polyamide is a copolyamide of formula A / XY, A being obtained by polycondensation of at least one amino acid or obtained by polycondensation of at least one lactam, X being chosen from B or P or BAC and Y being terepthalic and / or isophthalic acid.

[0142] Advantageously, in this first variant, A / XY is chosen from the units 11 / BI / BT, 12 / BI / BT, 11 / BACI / BACT, 12 / BACI / BACT, 11 / BACI, 12 / BACI, 11 / PI / PT, 12 / PI / PT and one of their mixtures.

[0143] In a second variant, said at least one amorphous polyamide is a copolyamide of formula A / XY, A being obtained by polycondensation of at least one amino acid or obtained by polycondensation of at least one lactam, X being chosen from B or P and Y being sebacic acid or dodecanedioic acid.

[0144] Advantageously, in this second variant, A / XY is chosen from the patterns 11 / B10, 11 / B12, 11 / P10, 11 / P12, 12 / B10, 12 / B12, 12 / P10, 12 / P12, and one of their mixtures.

[0145] In a third variant, said at least one amorphous polyamide is a copolyamide of formula A / XY, A being obtained by polycondensation of at least one diamine Ca with at least one dicarboxylic acid Cb, X being chosen from B or P and Y being sebacic acid or dodecanedioic acid.

[0146] Advantageously, in this third variant, in which A / XY is chosen from the patterns 1010 / B10, 1010 / B12, 1010 / P10, 1010 / P12, 1012 / B10, 1012 / B12, 1012 / P10, 1012 / P12, 1210 / B10, 1210 / B12, 1210 / P10, 1210 / P12, 1212 / B10, 1212 / B12, 1212 / P10, 1212 / P12, and one of their mixtures.

[0147] In a fourth variant, said at least one amorphous polyamide is a homo-polyamide of formula XY, X being chosen from B or P and Y being sebacic acid or dodecanedioic acid.

[0148] Advantageously, in this fourth variant, XY is chosen from the units B10, B12, P10, P12, and one of their mixtures.

[0149] The initial composition Cl comprising said polyamide contains pollutants not present at the origin during its preparation but present in said product after use of said product.

[0150] The initial composition Cl comprising said polyamide may contain other constituents, volatile or non-volatile, present at the origin during its preparation and still present when said product is obtained after use of said product.

[0151] In one embodiment, said volatile constituents are chosen from constituents having a boiling point below 500°C, preferably 400°C, advantageously below 350°C at atmospheric pressure, in particular chosen from plasticizers, monomers and oligomers having a degree of polymerization. rization less than or equal to 3, and organic stabilizers.

[0152] The expression “atmospheric pressure” means 1013.25 hPa, or 1013.25 mb, or 760 mmHg, said pressure being measured at sea level.

[0153] Certain constituents may be degraded before their boiling point under atmospheric pressure and must then be removed under reduced pressure.

[0154] In one embodiment, said constituents are volatile compounds under reduced pressure, i.e. the boiling point of said constituents is less than 300°C, preferably less than 250°C, advantageously less than 200°C under 5 hPa of pressure.

[0155] The monomers correspond to the lactams and / or amino acids and / or diamines and carboxylic acids introduced to obtain the polyamide during its polycondensation.

[0156] The oligomers having a degree of polymerization less than or equal to 3, are derived from the monomers introduced above and correspond to the dimers or trimers which may or may not be cyclic.

[0157] Organic stabilizers, although they can be used alone, are more generally a combination of organic stabilizers, such as a primary antioxidant of the phenol type (for example of the type of irganox® 245 or 1098 or 1010 from BASF), a secondary antioxidant of the phosphite type and possibly other stabilizers such as a HALS, which means Hindered Amine Light Stabilizer or hindered amine light stabilizer (for example Tinuvin® 770 from BASF), an anti-UV (for example Tinuvin® 312 from BASF), a phenolic or phosphorus-based stabilizer. It is also possible to use amine-type antioxidants such as Naugard™ 445 from SI group or polyfunctional stabilizers such as Nylostab® S-EED from Clariant.

[0158] Said non-volatile constituents are chosen from impact modifiers, fillers, additives.

[0159] Additives are therefore non-volatile constituents.

[0160] The initial composition Cl comprises an initial polyamide and optionally the other constituents as well as pollutants and is present at the origin in said element of said product after use.

[0161] In particular, the present invention relates to said initial composition which comprises pollutants originating from the use of said product and one or more volatile or non-volatile constituent(s), in particular which comprises one or more volatile or non-volatile constituent(s) before use, as defined above, said composition being called Cl and comprising by weight:

[0162] (a) from 30 to 99.9% of polyamide, in particular from 50 to 99.5% by weight, in particular from 75% to 99.5% by weight,

[0163] (b) from 0 to 15% of plasticizer, in particular from 0.1 to 15.0% by weight,

[0164] (c) from 0 to 30% of impact modifiers, in particular from 1 to 15.0% by weight,

[0165] (d) from 0 to 5% of additives, in particular from 0.1 to 5.0% by weight,

[0166] (e) from 0 to 6% by weight, in particular from 0.1 to 5%, in particular from 1 to 4% by weight of a compound chosen from monomers and oligomers having a degree of polymerization less than or equal to 3, and organic stabilizers,

[0167] (f) from 0 to 50% by weight of fibers and / or fillers,

[0168] (g) 0.1 to 20% by weight of pollutants, in particular from 0.5 to 15%, in particular from 0.5 to 10%, more particularly 0.5 to 5%,

[0169] the sum of components (a) to (g) being equal to 100% and the sum of volatile constituents (b), (e) and pollutants (g) being from 0.1 to 41% by weight, relative to the total weight of said composition Cl, in particular from 0.5 to 25%, in particular from 0.5 to 20%.

[0170] In a first variant, said composition Cl comprises by weight:

[0171] (a) from 30% to 99.8% of polyamide, in particular from 50 to 99.4%, in particular from 75% at 99.4% by weight,

[0172] (b) from 0.1 to 15.0% by weight of plasticizer,

[0173] (c) from 0 to 30% of impact modifiers, in particular from 1 to 15.0% by weight,

[0174] (d) from 0 to 5% of additives, in particular from 0.1 to 5.0% by weight,

[0175] (e) from 0 to 6% by weight, in particular from 0.1 to 5%, in particular from 1 to 4% by weight of a compound chosen from monomers and oligomers having a degree of polymerization less than or equal to 3, and organic stabilizers,

[0176] (f) from 0 to 50% by weight of fibers and / or fillers,

[0177] (g) 0.1 to 20% by weight of pollutants, in particular from 0.5 to 15%, in particular from 0.5 to 10%, more particularly 0.5 to 5%,

[0178] the sum of components (a) to (g) being equal to 100% and the sum of volatile constituents (b), (e) and pollutants (g) being from 0.2 to 41% by weight, relative to the total weight of said composition Cl, in particular from 0.6 to 25%, notably from 0.6 to 20%.

[0179] In a second variant, said composition Cl comprises by weight:

[0180] (a) from 30% to 98.9% of polyamide, in particular from 50 to 98.5%, in particular from 75% at 98.5% by weight,

[0181] (b) from 0 to 15% of plasticizer, in particular from 0.1 to 15.0% by weight.

[0182] (c) from 1 to 30.0% by weight of impact modifiers.

[0183] (d) from 0 to 5% of additives, in particular from 0.1 to 5.0% by weight.

[0184] (e) from 0 to 6% by weight, in particular from 0.1 to 5%, in particular from 1 to 4% by weight of a compound chosen from monomers and oligomers having a degree of polymerization less than or equal to 3, and organic stabilizers,

[0185] (f) from 0 to 50% by weight of fibers and / or fillers,

[0186] (g) 0.1 to 20% by weight of pollutants, in particular from 0.5 to 15%, in particular from 0.5 to 10%, more particularly 0.5 to 5%,

[0187] the sum of components (a) to (g) being equal to 100% and the sum of volatile constituents (b), (e) and pollutants (g) being from 0.1 to 41% by weight, relative to the total weight of said composition Cl, in particular from 0.5 to 25%, in particular from 0.5 to 20%.

[0188] In a third variant, said composition Cl comprises by weight:

[0189] (a) from 30% to 99.8% of polyamide, in particular from 50 to 99.4%, in particular from 75% at 99.4% by weight,

[0190] (b) from 0 to 15% of plasticizer, in particular from 0.1 to 15.0% by weight.

[0191] (c) from 0 to 30% of impact modifiers, in particular from 1 to 15.0% by weight.

[0192] (d) from 0.1 to 5.0% by weight of additives.

[0193] (e) from 0 to 6% by weight, in particular from 0.1 to 5%, in particular from 1 to 4% by weight of a compound chosen from monomers and oligomers having a degree of polymerization less than or equal to 3, and organic stabilizers,

[0194] (f) from 0 to 50% by weight of fibers and / or fillers

[0195] (g) 0.1 to 20% by weight of pollutants, in particular from 0.5 to 15%, in particular from 0.5 to 10%, more particularly 0.5 to 5%,

[0196] the sum of components (a) to (g) being equal to 100% and the sum of volatile constituents (b), (e) and pollutants (g) being from 0.1 to 41% by weight, relative to the total weight of said composition Cl, in particular from 0.5 to 25%, in particular from 0.5 to 20%.

[0197] In a fourth variant, said composition Cl comprises by weight:

[0198] (a) from 30% to 99.8% of polyamide, in particular from 50 to 99.4%, in particular from 75% at 99.4% by weight,

[0199] (b) from 0 to 15% of plasticizer, in particular from 0.1 to 15.0% by weight.

[0200] (c) from 0 to 30% of impact modifiers, in particular from 1 to 15.0% by weight.

[0201] (d) from 0 to 5% of additives, in particular from 0.1 to 5.0% by weight of additives.

[0202] (e) from 0.1 to 5%, in particular from 1 to 4% by weight of a compound chosen from monomers and oligomers having a degree of polymerization less than or equal to 3, and organic stabilizers,

[0203] (f) from 0 to 50% by weight of fibers and / or fillers

[0204] (g) 0.1 to 20% by weight of pollutants, in particular from 0.5 to 15%, in particular from 0.5 to 10%, more particularly 0.5 to 5%,

[0205] the sum of components (a) to (g) being equal to 100% and the sum of volatile constituents (b), (e) and pollutants (g) being comprised from 0.2 to 40% by weight, relative to the total weight of said composition Cl, in particular from 0.6 to 25%, in particular from 0.6 at 20%.

[0206] In a fifth variant, said initial composition Cl comprises by weight:

[0207] (a) from 30 to 98.9% of polyamide, in particular from 50 to 98.5% by weight, in particular from 75% to 98.5% by weight,

[0208] (b) from 0 to 15% of plasticizer, in particular from 0.1 to 15.0% by weight,

[0209] (c) from 0 to 30% of impact modifiers, in particular from 1 to 15.0% by weight,

[0210] (d) from 0 to 5% of additives, in particular from 0.1 to 5.0% by weight,

[0211] (e) from 0 to 6% by weight, in particular from 0.1 to 5%, in particular from 1 to 4% by weight of a compound chosen from monomers and oligomers having a degree of polymerization less than or equal to 3, and organic stabilizers,

[0212] (f) from 1 to 50% by weight of fibers and / or fillers,

[0213] (g) 0.1 to 20% by weight of pollutants, in particular from 0.5 to 15%, in particular from 0.5 to 10%, more particularly 0.5 to 5%,

[0214] the sum of components (a) to (g) being equal to 100% and the sum of volatile constituents (b), (e) and pollutants (g) being from 0.1 to 41% by weight, relative to the total weight of said composition Cl, in particular from 1.1 to 25%, notably from 1.1 to 20%.

[0215] In a sixth variant, said initial composition Cl comprises by weight:

[0216] (a) from 30 to 99.4% of polyamide, in particular from 50 to 99.4% by weight, in particular from 75% to 99.4% by weight,

[0217] (b) from 0.1 to 15% by weight of plasticizer,

[0218] (c) from 0 to 30% of impact modifiers, in particular from 1 to 15.0% by weight,

[0219] (d) from 0 to 5% of additives, in particular from 0.1 to 5.0% by weight,

[0220] (e) from 0 to 6% by weight, in particular from 0.1 to 5%, in particular from 1 to 4% by weight of a compound chosen from monomers and oligomers having a degree of polymerization less than or equal to 3, and organic stabilizers,

[0221] (f) from 0 to 50% by weight of fibers and / or fillers,

[0222] (g) from 0.5 to 15% by weight of pollutants, in particular from 0.5 to 10%, more particu mainly from 0.5 to 5%,

[0223] the sum of components (a) to (g) being equal to 100% and the sum of volatile constituents (b), (e) and pollutants (g) being comprised from 0.6 to 36% by weight, relative to the total weight of said composition Cl, in particular from 0.7 to 25%, in particular from 1.6 to 20%.

[0224] In a seventh variant, said initial composition Cl comprises by weight:

[0225] (a) from 30 to 99.4% of polyamide, in particular from 50 to 99.4% by weight, in particular from 75% to 99.4% by weight,

[0226] (b) from 0.1 to 15% by weight of plasticizer,

[0227] (c) from 0 to 30% of impact modifiers, in particular from 1 to 15.0% by weight,

[0228] (d) from 0 to 5% of additives, in particular from 0.1 to 5.0% by weight,

[0229] (e) from 0 to 6% by weight, in particular from 0.1 to 5%, in particular from 1 to 4% by weight of a compound chosen from monomers and oligomers having a degree of polymerization less than or equal to 3, and organic stabilizers,

[0230] (f) from 0 to 50% by weight of fibers and / or fillers,

[0231] (g) from 0.5 to 15% by weight of pollutants, in particular from 0.5 to 10%, more particu mainly from 0.5 to 5%,

[0232] the sum of components (a) to (g) being equal to 100% and the sum of volatile constituents (b), (e) and pollutants (g) being comprised from 0.6 to 36% by weight, relative to the total weight of said composition Cl, in particular from 0.7 to 25%, in particular from 1.6 to 20%.

[0233] In one embodiment, said composition Cl consists of, by weight:

[0234] (a) from 30 to 99.9% of polyamide, in particular from 50 to 99.5% by weight, in particular from 75% to 99.5% by weight,

[0235] (b) from 0 to 15% of plasticizer, in particular from 0.1 to 15.0% by weight,

[0236] (c) from 0 to 30% of impact modifiers, in particular from 1 to 15.0% by weight,

[0237] (d) from 0 to 5% of additives, in particular from 0.1 to 5.0% by weight,

[0238] (e) from 0 to 6% by weight, in particular from 0.1 to 5%, in particular from 1 to 4% by weight of a compound chosen from monomers and oligomers having a degree of polymerization less than or equal to 3, and organic stabilizers,

[0239] (f) from 0 to 50% by weight of fibers and / or fillers,

[0240] (g) 0.1 to 20% by weight of pollutants, in particular from 0.5 to 15%, in particular from 0.5 to 10%, more particularly 0.5 to 5%,

[0241] the sum of components (a) to (g) being equal to 100% and the sum of volatile constituents (b), (e) and pollutants (g) being from 0.1 to 41% by weight, relative to the total weight of said composition Cl, in particular from 0.5 to 25%, in particular from 0.5 to 20%.

[0242] In a first variant of this embodiment, said composition Cl consists of, by weight:

[0243] (a) from 30% to 99.8% of polyamide, in particular from 50 to 99.4%, in particular from 75% at 99.4% by weight,

[0244] (b) from 0.1 to 15.0% by weight of plasticizer,

[0245] (c) from 0 to 30% of impact modifiers, in particular from 1 to 15.0% by weight,

[0246] (d) from 0 to 5% of additives, in particular from 0.1 to 5.0% by weight,

[0247] (e) from 0 to 6% by weight, in particular from 0.1 to 5%, in particular from 1 to 4% by weight of a compound chosen from monomers and oligomers having a degree of polymerization less than or equal to 3, and organic stabilizers,

[0248] (f) from 0 to 50% by weight of fibers and / or fillers,

[0249] (g) 0.1 to 20% by weight of pollutants, in particular from 0.5 to 15%, in particular from 0.5 to 10%, more particularly 0.5 to 5%,

[0250] the sum of components (a) to (g) being equal to 100% and the sum of volatile constituents (b), (e) and pollutants (g) being from 0.2 to 41% by weight, relative to the total weight of said composition Cl, in particular from 0.6 to 25%, in particular from 0.6 to 20%.

[0251] In a second variant of this embodiment, said composition Cl consists of, by weight:

[0252] (a) from 30% to 98.9% of polyamide, in particular from 50 to 98.5%, in particular from 75% at 98.5% by weight,

[0253] (b) from 0 to 15% of plasticizer, in particular from 0.1 to 15.0% by weight.

[0254] (c) from 1 to 30.0% by weight of impact modifiers.

[0255] (d) from 0 to 5% of additives, in particular from 0.1 to 5.0% by weight.

[0256] (e) from 0 to 6% by weight, in particular from 0.1 to 5%, in particular from 1 to 4% by weight of a compound chosen from monomers and oligomers having a degree of polymerization less than or equal to 3, and organic stabilizers,

[0257] (f) from 0 to 50% by weight of fibers and / or fillers,

[0258] (g) 0.1 to 20% by weight of pollutants, in particular from 0.5 to 15%, in particular from 0.5 to 10%, more particularly 0.5 to 5%,

[0259] the sum of components (a) to (g) being equal to 100% and the sum of volatile constituents (b), (e) and pollutants (g) being comprised from 0.1 to 41% by weight, relative to the total weight of said composition Cl, in particular from 0.5 to 25%, in particular from 0.5 to 20%.

[0260] In a third variant of this embodiment, said composition Cl is made up of, by weight:

[0261] (a) from 30% to 99.8% of polyamide, in particular from 50 to 99.4%, in particular from 75% at 99.4% by weight,

[0262] (b) from 0 to 15% of plasticizer, in particular from 0.1 to 15.0% by weight.

[0263] (c) from 0 to 30% of impact modifiers, in particular from 1 to 15.0% by weight.

[0264] (d) from 0.1 to 5.0% by weight of additives.

[0265] (e) from 0 to 6% by weight, in particular from 0.1 to 5%, in particular from 1 to 4% by weight of a compound chosen from monomers and oligomers having a degree of polymerization less than or equal to 3, and organic stabilizers,

[0266] (f) from 0 to 50% by weight of fibers and / or fillers

[0267] (g) 0.1 to 20% by weight of pollutants, in particular from 0.5 to 15%, in particular from 0.5 to 10%, more particularly 0.5 to 5%,

[0268] the sum of components (a) to (g) being equal to 100% and the sum of volatile constituents (b), (e) and pollutants (g) being between 0.1 and 41% by weight, relative to to the total weight of said composition Cl, in particular from 0.5 to 25%, in particular from 0.5 to 20%.

[0269] In a fourth variant of this embodiment, said composition Cl consists of, by weight:

[0270] (a) from 30% to 99.8% of polyamide, in particular from 50 to 99.4%, in particular from 75% at 99.4% by weight,

[0271] (b) from 0 to 15% of plasticizer, in particular from 0.1 to 15.0% by weight.

[0272] (c) from 0 to 30% of impact modifiers, in particular from 1 to 15.0% by weight.

[0273] (d) from 0 to 5% of additives, in particular from 0.1 to 5.0% by weight of additives.

[0274] (e) from 0.1 to 5%, in particular from 1 to 4% by weight of a compound chosen from monomers and oligomers having a degree of polymerization less than or equal to 3, and organic stabilizers,

[0275] (f) from 0 to 50% by weight of fibers and / or fillers

[0276] (g) 0.1 to 20% by weight of pollutants, in particular from 0.5 to 15%, in particular from 0.5 to 10%, more particularly 0.5 to 5%,

[0277] the sum of components (a) to (g) being equal to 100% and the sum of volatile constituents (b), (e) and pollutants (g) being comprised from 0.2 to 40% by weight, relative to the total weight of said composition Cl, in particular from 0.6 to 25%, notably from 0.6 to 20%.

[0278] In a fifth variant of this embodiment, said initial composition Cl consists of, by weight:

[0279] (a) from 30 to 98.9% of polyamide, in particular from 50 to 98.5% by weight, in particular from 75% to 98.5% by weight,

[0280] (b) from 0 to 15% of plasticizer, in particular from 0.1 to 15.0% by weight,

[0281] (c) from 0 to 30% of impact modifiers, in particular from 1 to 15.0% by weight,

[0282] (d) from 0 to 5% of additives, in particular from 0.1 to 5.0% by weight,

[0283] (e) from 0 to 6% by weight, in particular from 0.1 to 5%, in particular from 1 to 4% by weight of a compound chosen from monomers and oligomers having a degree of polymerization less than or equal to 3, and organic stabilizers,

[0284] (f) from 1 to 50% by weight of fibers and / or fillers,

[0285] (g) 0.1 to 20% by weight of pollutants, in particular from 0.5 to 15%, in particular from 0.5 to 10%, more particularly 0.5 to 5%,

[0286] the sum of components (a) to (g) being equal to 100% and the sum of volatile constituents (b), (e) and pollutants (g) being from 0.1 to 41% by weight, relative to the total weight of said composition Cl, in particular from 1.1 to 25%, notably from 1.1 to 20%.

[0287] In a sixth variant of this embodiment, said initial composition Cl consists of, by weight:

[0288] (a) from 30 to 99.4% of polyamide, in particular from 50 to 99.4% by weight, in particular from 75% to 99.4% by weight,

[0289] (b) from 0.1 to 15% by weight of plasticizer,

[0290] (c) from 0 to 30% of impact modifiers, in particular from 1 to 15.0% by weight,

[0291] (d) from 0 to 5% of additives, in particular from 0.1 to 5.0% by weight,

[0292] (e) from 0 to 6% by weight, in particular from 0.1 to 5%, in particular from 1 to 4% by weight of a compound chosen from monomers and oligomers having a degree of polymerization less than or equal to 3, and organic stabilizers,

[0293] (f) from 0 to 50% by weight of fibers and / or fillers,

[0294] (g) from 0.5 to 15% by weight of pollutants, in particular from 0.5 to 10%, more particu mainly from 0.5 to 5%,

[0295] the sum of components (a) to (g) being equal to 100% and the sum of volatile constituents (b), (e) and pollutants (g) being from 0.6 to 36% by weight, relative to the total weight of said composition Cl, in particular from 0.7 to 25%, in particular from 1.6 to 20%.

[0296] In a seventh variant of this embodiment, said initial composition Cl consists of, by weight:

[0297] (a) from 30 to 99.4% of polyamide, in particular from 50 to 99.4% by weight, in particular from 75% to 99.4% by weight,

[0298] (b) from 0.1 to 15% by weight of plasticizer,

[0299] (c) from 0 to 30% of impact modifiers, in particular from 1 to 15.0% by weight,

[0300] (d) from 0 to 5% of additives, in particular from 0.1 to 5.0% by weight,

[0301] (e) from 0 to 6% by weight, in particular from 0.1 to 5%, in particular from 1 to 4% by weight of a compound chosen from monomers and oligomers having a degree of polymerization less than or equal to 3, and organic stabilizers,

[0302] (f) from 0 to 50% by weight of fibers and / or fillers,

[0303] (g) from 0.5 to 15% by weight of pollutants, in particular from 0.5 to 10%, more particu mainly from 0.5 to 5%,

[0304] the sum of components (a) to (g) being equal to 100% and the sum of volatile constituents (b), (e) and pollutants (g) being from 0.6 to 36% by weight, relative to the total weight of said composition Cl, in particular from 0.7 to 25%, in particular from 1.6 to 20%.

[0305] This initial composition Cl which comprises the initial polyamide and optionally its other constituents and which also corresponds to the polyamide to be recycled is therefore constitutive of an element of a product obtained after the implementation of said polyamide but after use of said product. It will therefore constitute “post-consumer” waste.

[0306] The plasticizer is optional and comprised from 0 to 15.0%, in particular from 0.1 to 15.0% in weight.

[0307] For example, the plasticizers are chosen from benzene sulfonamide derivatives such as n-butyl benzene sulfonamide (BBSA), the ortho and para isomers of ethyl toluene sulfonamide (ETSA), N-cyclohexyl toluene sulfonamide and N-(2-hydroxypropyl) benzene sulfonamide (HP-BSA),

[0308] hydroxybenzoic acid esters such as 2-ethylhexyl para-hydroxybenzoate (EHPB) and 2-decylhexyl para-hydroxybenzoate (HDPB),

[0309] esters or ethers of tetrahydrofurfuryl alcohol such as oligoethyleneoxy-tetrahydrofurfuryl alcohol, and esters of citric acid or hydroxymalonic acid, such as oligoethyleneoxymalonate.

[0310] A preferred plasticizer is n-butyl benzene sulfonamide (BBSA).

[0311] The impact modifier is optional and comprised from 0 to 30%, in particular from 1 to 15% by weight.

[0312] The impact modifier is advantageously constituted by a polymer having a flexural modulus of less than 100 MPa measured according to the ISO 178 standard and a Tg of less than 0°C (measured according to the 11357-2 standard at the inflection point of the DSC thermogram), in particular a polyolefin.

[0313] The polyolefin of the impact modifier may be functionalized or non-functionalized or be a mixture of at least one functionalized and / or at least one non-functionalized.

[0314] The additive is optional and comprised from 0 to 5.0%, in particular from 0.1 to 5.0% by weight.

[0315] The additive is chosen from colorants, inorganic stabilizers, catalysts, surfactants, nucleating agents, pigments, brighteners, antioxidants, lubricants, flame retardants, natural waxes, bases and mixtures thereof.

[0316] In one embodiment, the additive is selected from colorants, inorganic stabilizers, surfactants, nucleating agents, pigments, brighteners, antioxidants, lubricants, flame retardants, natural waxes, bases and mixtures thereof.

[0317] The term "catalyst" means a polycondensation catalyst such as a mineral or organic acid.

[0318] Advantageously, the catalyst is chosen from phosphoric acid (H3PO4), phosphorous acid (H3PO3), hypophosphorous acid (H3PO2), or a mixture thereof.

[0319] Advantageously, said composition Cl before use of said product has a catalyst content by weight of from 0 to 6000 ppm, preferably from 0 to 3400 ppm, advantageously from 0 to 1000 ppm relative to the total weight of the composition CL.

[0320] Advantageously, when said product is a single-layer or multi-layer structure ticlée, said polyamide of said structure before its use has a catalyst content by weight of from 0 to 9000, in particular from 0 to 6000 ppm, preferably from 0 to 3400 ppm, advantageously from 0 to 1000 ppm relative to the total weight of the polyamide or of the composition comprising it or constituting it.

[0321] The fibers and / or fillers are optional and their proportion is from 0 to 50% by weight.

[0322] By way of example, the fibers may be chosen from aramid fibers, glass fibers, carbon fibers, advantageously glass fibers or carbon fibers.

[0323] By way of example, the fillers may be chosen from silica, graphite, expanded graphite, carbon black, glass beads, kaolin, magnesia, slag, talc, wollastonite, nanofillers (carbon nanotubes), pigments, metal oxides (titanium oxide), metals, advantageously wollastonite and talc, preferentially talc.

[0324] In one embodiment, said pollutants are volatile compounds at atmospheric pressure, i.e. the boiling point of said pollutants is less than 500°C, preferably 400°C, advantageously less than 350°C.

[0325] In another embodiment, said pollutants are volatile compounds under reduced pressure, that is to say that the boiling point of said pollutants is less than 300°C, preferably 250°C, advantageously less than 200°C under 5 hPa of pressure.

[0326] In yet another embodiment, said constituents are volatile compounds at atmospheric pressure, i.e. the boiling point of said pollutants is less than 500°C, preferably 400°C, advantageously less than 350°C.

[0327] In yet another embodiment, said constituents are volatile compounds under reduced pressure, i.e. the boiling point of said pollutants is less than 300°C, preferably 250°C, advantageously less than 200°C under 5 hPa of pressure.

[0328] In one embodiment, the polyamide to be recycled of composition C1 is devoid of catalyst.

[0329] In one embodiment, when said product is a single-layer or multi-layer structure, said volatile compounds are chosen from the fluids transported by said structure, a plasticizer, a monomer and an oligomer having a degree of polymerization less than or equal to 3, an organic stabilizer and a mixture thereof.

[0330] Advantageously, said fluid is chosen from ethylene glycol, water, gasoline, in particular alcoholic gasoline, and hydrocarbons.

[0331] In one embodiment, said volatile compound is a plasticizer. Regarding the process

[0332] Said method comprises steps a) to f) as defined above.

[0333] The purpose of the process is to recycle a polyamide originating from at least one product obtained during or after the processing of said polyamide by extrusion, by extrusion-blow molding, by rotational molding, by injection or by 3D printing, and to be able to eliminate or at least reduce the proportion of pollutants originating from the use of said product and of volatile constituents originally present in said product and in particular in said polyamide.

[0334] Another purpose of said polyamide is to be able to recycle certain constituents originally present in said polyamide.

[0335] Advantageously, the aim is to be able to eliminate or at least reduce the proportion of pollutants originating from the use of said product and of volatile constituents present in said product and in particular in said polyamide.

[0336] More advantageously, the aim is to be able to eliminate or at least reduce the proportion of pollutants resulting from the use of said product.

[0337] The initial proportion of said pollutants in said product is from 0.1 to 20% by weight relative to the total weight of said composition, in particular from 0.5 to 15%, in particular from 0.5 to 10%, more particularly from 0.5 to 5%.

[0338] In the case where said product is made up of elements other than said polyamide, said proportion of said pollutants and said constituent(s) is predominantly if not entirely present in said polyamide.

[0339] The term “elements” designates any material present in the product and other than said polyamide. Mention may in particular be made of metals and polymer compositions comprising less than 30% of polymer, in particular of polyamide other than said polyamide.

[0340] Step a) of said process consists, if necessary, in treating said product to separate said polyamide from other elements which cannot be recycled with said process and are present in said products.

[0341] For example, when said product consists of a single-layer structure obtained by extrusion, extrusion-blow molding, rotational molding or injection, there are no elements other than polyamide and it is therefore not necessary to treat said product.

[0342] Conversely, when said product consists of a multilayer structure obtained by extrusion, extrusion-blow molding, rotational molding or injection, there are other elements than polyamide in said structure. For example, when the structure corresponds to a multilayer pipe, granule, film, sheet or hollow body, it comprises a layer of polyamide and at least one other layer of a different polymer, for example EVOH (ethylene vinyl alcohol), polyolefin, or a polyamide of a type other than said polyamide to be recycled, or even metallic, such as example in an offshore pipe. The other elements therefore correspond to this other layer or layers.

[0343] The separation of said polyamide layer from the other layer(s) can be done when the layers are not glued, by cutting the objects if necessary. For example, the pipe is cut in two lengthwise. If the layers are glued, the separation can be done by peeling.

[0344] When said structure corresponds to a structure obtained by injection, for example an article in the field of sport, industry, electronics and optics. The different elements can be separated for example by peeling, dissolving the glue, removing the screws or fixing elements.

[0345] When said structure corresponds to a structure obtained by rotational molding or by extrusion-blow molding, for example a tank or a hollow body, the treatment is similar to that used for structures obtained by extrusion.

[0346] Step b) corresponds, if necessary, to shaping said product or said polyamide separated in step a) so that it can be introduced into a system capable of melting and transporting a polyamide continuously.

[0347] Depending on the state in which said untreated product in step a) or said polyamide separated after treatment in step a) is present, it may be necessary to carry out shaping in the case where said untreated product in step a) or said polyamide separated after treatment in step a) cannot be introduced directly into a system capable of melting and transporting a polyamide continuously.

[0348] Said shaping can then be mechanical or cryogenic grinding to obtain particles having a volume diameter (D50) of less than 3 cm, preferably less than 1 cm, solubilization-reprecipitation, shredding, or cutting to obtain particles having a D50 of less than 3 cm, preferably less than 1 cm in these last three cases.

[0349] Preferably, the products are optionally shredded and then ground to obtain particles having a D50 of less than 1 cm.

[0350] The volume diameters of the particles (D10, D50 and D90) are defined according to the ISO 9276:2014 standard.

[0351] The “D50” corresponds to the volume average diameter, that is to say the value of the particle size which divides the population of particles examined exactly in two.

[0352] Step c) consists of introducing said untreated product and optionally shaped in step b) or said polyamide separated from step a) and optionally shaped in step b) into a system capable of melting, in particular an extruder.

[0353] In one embodiment, the extruder is excluding a multi-rotational system extruder.

[0354] In another embodiment, the extruder is selected from an extruder single screw and a twin screw extruder, in particular the extruder is a single screw extruder.

[0355] The temperature higher than the Tf of said polyamide if it is semi-crystalline or higher than the Tg of said polyamide if it is amorphous makes it possible to obtain said product or said polyamide in the molten state.

[0356] Step d) consists of introducing the product in the molten state obtained in step c) into a system capable of continuously transporting a polymer and having a degassing surface, in particular under reduced pressure.

[0357] Said system capable of continuously transporting a polymer comprises a heated vertical cylindrical part (11), in particular by double jacket, a distributor ring (4') making it possible to equally distribute the molten product to the upper part of the cylindrical part, in particular to the upper part of the double jacket, and a rotor 6).

[0358] In one embodiment, the rotor and distributor ring are heated.

[0359] Advantageously, the degassing system does not include a cold part in the cylindrical part in order to eliminate any possible condensation in the cylindrical part.

[0360] The expression “cold room” means an unheated room.

[0361] The degassing surface or zone may also be referred to as the evaporation surface or zone.

[0362] The degassing surface or zone makes it possible to reduce or eliminate pollutants and constituents which correspond to volatile compounds under atmospheric pressure.

[0363] The number-average molecular mass Mn of said polyamide to be recycled is preferably greater than or equal to 10,000 g / mol, in particular from 10,000 to 85,000 g / mol, in particular from 10,000 to 60,000 g / mol, in particular from 10,000 to 50,000 g / mol, more particularly from 10,000 to 40,000 g / mol, even more particularly from 10,000 to 30,000 g / mol.

[0364] Beyond 85,000, the polyamide in the molten state is too viscous for said constituents to be able to be eliminated or reduced by degassing.

[0365] In the latter case, it is possible to reduce the viscosity by dilution or by reacting the polyamide with molecules of lower number-average molecular mass Mn to achieve the preferred number-average molecular masses Mn.

[0366] In one embodiment, said system is a thin film evaporator.

[0367] Step e) makes it possible to distribute the product introduced by the feed (4) in step d) by means of the rotor (6) whose blades make it possible to spread said product in the form of a thin film with high turbulence over the entire wall of the heated vertical cylindrical part (5). The product descends towards the foot (lower bearing (7)) of the cylindrical part, following a helical movement along the internal wall of said part during in which the evaporation of volatile products takes place.

[0368] This step is carried out with degassing, in particular under reduced pressure, continuously in the molten state of said product at a temperature higher than the Tf of said polyamide if it is semi-crystalline or higher than the Tg of said polyamide if it is amorphous, to reduce or eliminate said pollutants and said one or more constituent(s).

[0369] The vapors which form rise counter-currently to the top of the device and pass through a separator (3).

[0370] The entrained droplets and foams are retained and fall back into the evaporation zone.

[0371] Vapors released from the liquid particles are released at the upper level (10) and pass into a condenser (not shown), a column (not shown), or any other subsequent process stage.

[0372] This step therefore makes it possible to reduce or eliminate pollutants which correspond to volatile compounds under atmospheric pressure, in particular under reduced pressure.

[0373] It also makes it possible to eliminate constituents which correspond to volatile compounds under atmospheric pressure, in particular under reduced pressure.

[0374] It is also possible to use a co-current technology in which the vapors that form descend in co-current to the bottom of the apparatus (7) from where they are eliminated.

[0375] Step f) allows the obtaining of a final composition C2 of molten polyamide which is recovered in the lower part (7) in the form of concentrate (8).

[0376] This step is identical for co-current technology or counter-current technology.

[0377] The vacuum applied for the reduced pressure is in particular between 100 and 0.01 hPa, preferably between 60 and 0.1 hPa, in particular between 40 hPa and 0.1 hPa, in particular between 25 hPa and 0.5 hPa, in particular between 3 hPa and 1 hPa.

[0378] The rotor speed is from 10 to 1000 rotations per minute, preferably from 50 to 300 rotations per minute.

[0379] The thickness of the film on the cylindrical part is in particular from 0.01 to 5 mm, preferably from 0.1 to 0.5 mm.

[0380] The evaporation surface is from 0.5 to 50 m2, preferably from 5 to 25 m2.

[0381] In one embodiment, said temperature is from 150°C to 350°C, in particular from 200°C to 300°C.

[0382] In a first variant of this embodiment, the pollutant is oil, in particular crude oil, and said temperature is between 180 and 350°C, preferably between 250 and 300°C.

[0383] In one embodiment of this first variant, the oil is present in the initial composition Cl in a proportion of less than 20% by weight, in particular less than 6% by weight.

[0384] In a second variant of this embodiment, the pollutant is an automotive fluid, in particular gasoline or a coolant and said temperature is between 180 and 350°C, preferably between 250 and 300°C.

[0385] In one embodiment of this second variant, said automotive fluid is present in the initial composition Cl in a proportion less than or equal to 20% by weight, in particular less than or equal to 15% by weight, in particular less than or equal to 10% by weight.

[0386] Nevertheless, the Mn of the polyamide to be recycled must not be too high because during recycling, said polyamide to be recycled will undergo a rise in viscosity post polycondensation during step d).

[0387] The number-average molecular mass Mn of said polyamide to be recycled is therefore preferably greater than or equal to 10,000 g / mol, in particular from 10,000 to 85,000 g / mol, in particular from 10,000 to 60,000 g / mol, in particular from 10,000 to 50,000 g / mol, more particularly from 10,000 to 40,000 g / mol, even more particularly from 10,000 to 30,000 g / mol.

[0388] Similarly, if the polyamide to be recycled comprises a catalyst, the proportion of said catalyst must be from 0 to 9000, in particular from 0 to 6000 ppm, preferably from 0 to 3400 ppm, advantageously from 0 to 1000 ppm relative to the total weight of the polyamide or of the composition comprising or constituting it.

[0389] In one embodiment, the degassing of step e) is carried out under reduced pressure for a time greater than or equal to 1 min, in particular from 1 to 5 min.

[0390] Below 1 min, the time is not sufficient to eliminate or sufficiently reduce the proportion of pollutants and constituents in said product or said polyamide.

[0391] Beyond 5 min, the proportion of pollutants and constituents which is eliminated or reduced in said product or said polyamide no longer varies significantly.

[0392] In another embodiment, said degassing surface is > 5000 mm2 / kg / h, from 5000 to 100,000 mm2 / kg / h, preferably from 6000 to 50,000 mm2 / kg / h, advantageously from 7,000 to 20,000 mm2 / kg / h.

[0393] In a first variant of this embodiment, the pollutant is oil, in particular crude oil, and said temperature is between 180 and 350°C, preferably between 250 and 300°C, the vacuum applied is less than 3 hPa, preferably 1 hPa, and the degassing surface is between 5000 mm2 / kg / h and 100,000 mm2 / kg / h, preferably between 10,000 and 50,000 kg / mm2 / kg / h.

[0394] In one embodiment of this first variant, the oil is present in the initial composition Cl in a proportion of less than 20% by weight, in particular less than or equal to 15% by weight, in particular less than or equal to 10%, more particularly less than or equal to 5% by weight.

[0395] In a second variant of this embodiment, the pollutant is an automotive fluid, in particular gasoline or a coolant, said temperature is between 180 and 350°C, preferably between 250 and 300°C, the vacuum applied is between 100 and 0.1 hPa, preferably between 60 and 5 hPa and the degassing surface is between 5000 mm2 / kg / h and 100,000 mm2 / kg / h, preferably between 6,000 and 25,000 kg / mm2 / kg / h.

[0396] In one embodiment of this second variant, said automotive fluid is present in the initial composition Cl in a proportion less than or equal to 20% by weight, in particular less than or equal to 15%, in particular less than 10% by weight.

[0397] In the case of a system capable of continuously transporting a polymer, in particular a thin-film evaporator where the polymer is otherwise spread in the form of a film, this is the surface area of ​​the molten polymer film subjected to degassing. This surface area data is available in the technical documents of the machines.

[0398] Advantageously, the degassing flow rate of step d) is > 100 kg / h, in particular > 150 kg / h.

[0399] More advantageously, the reduced pressure is from 0.1 hPa to 40 hPa, in particular from 0.5 hPa to 25 hPa.

[0400] The reduced pressure makes it possible to reduce and / or eliminate products that are volatile at atmospheric pressure but whose boiling point is too high at atmospheric pressure compared to the melting or degradation temperature to be able to be eliminated in said process. It is therefore necessary to reduce the pressure to lower the boiling point of said constituent and said pollutant so that they can be eliminated in said process.

[0401] It is then possible to recover said constituent and said pollutant which has been volatilized under the effect of degassing under reduced pressure, without degrading the polyamide to be recycled by exposure to a high temperature.

[0402] This is therefore another advantage of the invention, to be able on the one hand to recycle said polyamide originating from said product but also the constituent(s) and pollutants present in said product or polyamide.

[0403] In one embodiment, said constituent is a plasticizer, in particular N-butylbenzenesulfonamide (BBSA).

[0404] In one embodiment, said pollutants are eliminated to at least 60% by weight relative to the total weight of the pollutants present in said product or said polyamide, in particular to at least 70%, in particular to at least 80%, in particular to at least 85%, more particularly to at least 90%, even more particularly to at least 95%.

[0405] The majority of pollutants are therefore eliminated after this step d).

[0406] Step f) corresponds to obtaining a melted polyamide in the form of powder, ground material, granules or a new extruded part, said powder, ground material, granules or new extruded part having a proportion by weight of said constituents lower than the initial proportion present in said product, in particular <2%, in particular <1%, in particular <0.5% relative to the total weight of composition C2.

[0407] In one embodiment, the molten polyamide of step f) has an Mn greater than or equal to 500 g / mol, in particular between 500 and 85,000 g / mol, in particular between 500 and 60,000 g / mol, more particularly between 500 and 50,000 g / mol.

[0408] In one embodiment, the composition C1 comprises less than 15% of plasticizer, in particular BBSA and the extrusion of step d) is carried out under a pressure of less than 5 hPa, preferably less than 2 hPa, with a degassing surface area of ​​from 5000 mm2 / kg / h to 100,000 mm2 / kg / h, preferably of from 10,000 to 50,000 mm2 / kg / h and at a temperature of from 180 to 350°C, preferably of from 250 to 300°C.

[0409] In a first variant of the invention, in the process described above, at least one component chosen from molecules comprising one or more carboxylic acid functions, one or more primary amine functions, one or more alcohol functions and one or more ester functions, a base or a mixture thereof is added in step c).

[0410] The bases can be organic or inorganic, advantageously chosen from NaOH, KOH and carbonates.

[0411] When in particular said polyamide to be recycled from step c) is likely to increase in viscosity, in particular due to its chain ends and / or the presence of a catalyst and / or degassing under reduced pressure, it is necessary to add said component so as to control the increase in viscosity so as not to obtain a product that is too viscous and compatible with injection and extrusion applications.

[0412] Conversely, said polyamide to be recycled from step c) is capable of reacting with said component so as to lead to a polyamide with Mn lower than the initial Mn by means of degassing, possibly under reduced pressure.

[0413] The molten polyamide from step f) then has an Mn of from 500 to 35,000 g / mol, in particular from 500 to less than 10,000 g / mol, in particular from 500 to 5,000 g / mol.

[0414] The expression “molecule comprising one or more carbo- carboxylic acid, one or more primary amine functions, one or more alcohol functions and one or more ester functions” means any molecule having at least one carboxylic acid function or one amine function or one alcohol function or one ester function.

[0415] In another embodiment, said component is chosen from molecules comprising one or more carboxylic acid and primary amine functions.

[0416] In one embodiment, a single molecule is added whose functionality is comprised from 1 to 3.

[0417] The term functionality only concerns carboxylic acid and primary amine functions.

[0418] In another embodiment, several molecules are added whose average functionality is between 1.8 and 2.2.

[0419] In yet another embodiment, several molecules are added whose average functionality is between 0.8 and 1.2.

[0420] Advantageously, said molecule is a chain limiter.

[0421] In one embodiment, said chain limiter is selected from a C2-C18 aliphatic linear monocarboxylic acid, a C4-C18 aliphatic linear monoamine, a C3-C36 aliphatic linear dicarboxylic acid, a C4-C18 aliphatic linear diamine and a C6 to C18 aminocarboxylic acid and mixtures thereof.

[0422] A linear aliphatic C2-C18 monocarboxylic acid is for example acetic acid, propanoic acid, butanoic acid, pentanoic acid, hexanoic acid, heptanoic acid, octanoic acid, decanoic acid, undecanoic acid, dodecanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecanoic acid, heptadecanoic acid, octadecanoic acid.

[0423] Advantageously, said linear aliphatic monocarboxylic acid is C2-C12, in particular C2-C6, in particular acetic acid.

[0424] A linear aliphatic C4-C18 monoamine is, for example, 1-butylamine, 1-pentylamine, 1-hexylamine, 1-heptylamine, 1-octylamine, 1-nonylamine, 1-decylamine, 1-undecylamine, 1-dodecylamine, 1-tridecylamine, 1-tetradecylamine, 1-pentadecylamine, 1-hexadecylamine, 1-heptadecylamine, 1-octadecylamine.

[0425] Advantageously, said linear aliphatic monoamine is C4-C12, in particular C4-C6.

[0426] The linear aliphatic C3-C36 dicarboxylic acid (or dicarboxylic acid) can be chosen from malonic acid (3), succinic acid (4), pentanedioic acid (5), adipic acid (6), heptanedioic acid (7), octanedioic acid (8), azelaic acid (9), sebacic acid (10), undecanedioic acid (11), dodecanedioic acid (12), brassylic acid (13), tetradecanedioic acid (14), hexadecanedioic acid (16), octadecanedioic acid (18), octadecenedioic acid (18), eicosanedioic acid (20), docosanedioic acid (22) and fatty acid dimers containing 36 carbons.

[0427] The above-mentioned fatty acid dimers are dimerized fatty acids obtained by oligomerization or polymerization of long-chain unsaturated monobasic hydrocarbon fatty acids (such as linoleic acid and oleic acid), as described in particular in document EP 0 471 566.

[0428] Advantageously, said dicarboxylic acid is C3-C18, in particular C3-C12, in particular C3-C6.

[0429] Said linear aliphatic C4-C18 diamine may be chosen for example from butanediamine, pentanediamine, hexanediamine, heptanediamine, octanediamine, nonanediamine, decanediamine, undecanediamine, dodecanediamine, tridecanediamine, tetradecanediamine, hexadecanediamine, octadecanediamine and octadecenediamine.

[0430] Advantageously, said linear aliphatic diamine is C4-C12, in particular C4-C6.

[0431] The linear aliphatic diamines which have just been cited can all be bio-resourced within the meaning of the ASTM D6866 standard.

[0432] Said C6 to C18 aminocarboxylic acid.

[0433] It can thus be chosen from 6-aminohexanoic acid noted (6), 7-aminohexanoic acid (noted 7), 8-aminohexanoic acid (noted 8), 9-aminononanoic acid (noted 9), 10-aminodecanoic acid (noted 10), 11-aminoundecanoic acid (noted 11) and 12-aminododecanoic acid (noted 12),

[0434] Advantageously, said aminocarboxylic acid comprises from 9 to 12 carbon atoms, advantageously the aminocarboxylic acid is 11-aminoundecanoic acid.

[0435] In one embodiment, the chain limiter is chosen from a linear aliphatic dicarboxylic acid in C3-C36, in particular in C3-C18, more particularly in C3-C12, in particular in C3-C6.

[0436] In another embodiment, the chain limiter is adipic acid.

[0437] Advantageously, the proportion of said added component is from 0.01% to 10% by weight relative to the total weight of said shaped product or of said separate shaped polyamide from step b).

[0438] More advantageously, the proportion of said added component is from 0.01% to 5% by weight, in particular from 0.1 to 5%, in particular from 0.1 to 3%, more particularly from 0.1 to 1%.

[0439] In a second variant of the invention, in the method described above, step c) is carried out in the absence of at least one component chosen from molecules comprising one or more carboxylic acid functions, one or more primary amine functions, one or more alcohol functions and one or more ester functions or a mixture thereof.

[0440] In one embodiment, in the process defined above, the polyamide of the final composition C2 obtained in step f) after shaping in the form of granules or a new extruded part has an NH2 / COOH ratio of from 0.75 to 1.25, in particular from 0.92 to 1.08, preferably from 0.95 to 1.05, advantageously from 0.98 to 1.02, in particular from 0.99 to 1.01.

[0441] The NH2 / COOH ratio means the molar ratio of amine / carboxylic acid functions (including chain ends and functions that have reacted to form amide functions). This ratio can be determined after total hydrolysis of the PA and quantification of the amine and carboxylic acid functions by NMR.

[0442] Acidity and basicity are measured by potentiometry.

[0443] The acidity is measured according to the following method. A sample of polyamide is dissolved in benzyl alcohol. Then, this sample is determined by potentiometry with a 0.02N tetrabutylammonium hydroxide solution.

[0444] The basicity is measured according to the following method. A sample of polyamide is dissolved in metacresol. Then, this sample is assayed by potentiometry with a 0.02N perchloric acid solution.

[0445] According to another aspect, the present invention relates to a product capable of being obtained by the process as defined above.

[0446] With regard to recycled polyamide and the composition comprising it

[0447] Recycled polyamide therefore corresponds to the product obtained or likely to be obtained by the process of the invention.

[0448] Said recycled polyamide has an inherent viscosity, the inherent viscosity, as determined according to ISO 307:2007 in m-cresol at 20°C being greater than or equal to 1.0, in particular greater than or equal to 1.2 dl / g, in particular greater than or equal to 1.3 dl / g, in particular comprised from 1.3 dl / g to 1.8 dl / g.

[0449] Said recycled polyamide has an MFI of 0.1 to 50 g / 10 min.

[0450] MFI, short for Melt Flow Index, is the melt flow index. It is measured according to ISO 1133 at 235°C under 5 kg.

[0451] The proportion of pollutants in said composition after recycling is at least 2 times lower, in particular 3 times lower, in particular 4 times lower, more particularly 10 times lower compared to that present in the composition comprising the polyamide to be recycled.

[0452] According to another aspect, the present invention relates to the use of the granules obtained in step f. of the process defined above, for the preparation of articles obtained by extrusion.

[0453] The use of the granules defined above may require prior compounding to add certain compounds such as organic stabilizers, additives as defined above, in particular inorganic stabilizers or antioxidants.

[0454] The additives are as defined above.

[0455] In one embodiment, the article is a single-layer or multi-layer structure for transporting, distributing or storing fluids.

[0456] In a variant of this embodiment, said structure is chosen from a fluid transport pipe for an automobile.

[0457] In another variant of this embodiment, said structure is an oil or gas field exploitation pipe, underwater or on land.

[0458] According to another aspect, the present invention relates to the use of the granules obtained in step f. of the process defined above, for the preparation of articles obtained by injection.

[0459] In a variant of this embodiment, the article relates to applications in electrical or electronics, in particular electrical and electronic equipment goods, such as encapsulated solenoids, pumps, telephones, computers, printers, fax machines, modems, monitors, remote controls, cameras, circuit breakers, electrical cable sheaths, optical fibers, switches, multimedia systems, or applications in sports, in particular a ski boot or part of a ski boot or a rigid crampon shoe or part of a rigid crampon shoe, such as a football, rugby or American football shoe, a hockey shoe or part of a hockey shoe, or a running shoe, a golf ball or part of a golf ball, or a stick in the sport of lacrosse or a hockey article such as a helmet or sports articles for the protection of the head, shoulders, elbows, hands,knee, back or shin, such as helmet, gloves, shoulder pads, elbow pads, knee pads or shin guards or optical applications, in particular glasses or a mask, in particular glasses or a mask used in the practice of a sport such as protective glasses or a ski mask.

[0460] The present invention therefore makes it possible to separate the pollutants from the polyamide to be recycled and consequently to recycle said polyamides for new compounds, in particular polyamides.

[0461] It also makes it possible to separate the volatile constituents, such as the plasticizer, monomers, oligomers and organic stabilizers possibly present in the polyamide to be recycled.

[0462] Said separation may be partial. In particular it is substantially complete, that is to say that on the one hand the sum of the pollutants remaining after recycling is in particular less than or equal to 0.003% relative to the total weight of the final composition C2 and the sum of the pollutants and volatile constituents remaining after recycling is in particular less than or equal to 0.003% relative to the total weight of the final composition C2.

[0463] Regarding composition C2 obtained after recycling composition Cl

[0464] The Cl composition of the element, after recycling, is likely to have lost all or part of the pollutants present initially to lead to a C2 composition.

[0465] The composition Cl of the element, after recycling, is also likely to have lost all or part of the volatile constituent(s) possibly present initially to lead to said composition C2.

[0466] In particular, the present invention relates to the final composition after recycling of the composition Cl defined above, and called C2, comprising by weight:

[0467] (a) from 30 to 99.99999% of polyamide, in particular from 50 to 99.9999% by weight, in particular from 75% to 99.9990% by weight,

[0468] (b) from 0 to 1% of plasticizer, in particular from 0.001 to 1% by weight,

[0469] (c) from 0 to 30% of impact modifiers, in particular from 1 to 15.0% by weight,

[0470] (d) from 0 to 5% of additives, in particular from 0.1 to 5.0% by weight,

[0471] (e) from 0 to 1% by weight, in particular from 0.001 to 1% by weight of a chosen compound among monomers and oligomers having a degree of polymerization less than or equal to 3, and organic stabilizers,

[0472] (f) from 0 to 50% by weight of fibers and / or fillers,

[0473] (g) from 0 to 2% by weight of pollutants, in particular from 0.0001 to 1%, in particular of 0.001 to 0.1%,

[0474] the sum of components (a) to (g) being equal to 100% and the sum of volatile constituents (b), (e) and pollutants (g) being from 0.00001 to 4% by weight, relative to the total weight of said composition C2, in particular from 0.001 to 3%, in particular from 0.001 to 2.1%.

[0475] In a first variant, said composition C2 comprises by weight:

[0476] (a) from 30% to 99.999% of polyamide, in particular from 50 to 99.998%, in particular of 75% to 99.997% by weight,

[0477] (b) from 0.001 to 1% by weight of plasticizer,

[0478] (c) from 0 to 30% of impact modifiers, in particular from 1 to 15.0% by weight,

[0479] (d) from 0 to 5% of additives, in particular from 0.1 to 5.0% by weight,

[0480] (e) from 0 to 1% by weight, in particular from 0.001 to 1% by weight of a chosen compound among monomers and oligomers having a degree of polymerization less than or equal to 3, and organic stabilizers,

[0481] (f) from 0 to 50% by weight of fibers and / or fillers,

[0482] (g) from 0 to 2% by weight of pollutants, in particular from 0.001 to 1%, in particular of 0.001 to 0.1%,

[0483] the sum of components (a) to (g) being equal to 100% and the sum of volatile constituents (b), (e) and pollutants (g) being from 0.001 to 4% by weight, relative to the total weight of said composition C2, in particular from 0.002 to 3%, in particular from 0.002 to 2.1%.

[0484] In a second variant, said composition C2 comprises by weight:

[0485] (a) from 30% to 99% of polyamide, in particular from 50 to 98.999%, in particular from 75% at 98.998% by weight,

[0486] (b) from 0 to 1% of plasticizer, in particular from 0.001 to 1% by weight,

[0487] (c) from 1 to 15.0% by weight of impact modifiers,

[0488] (d) from 0 to 5% of additives, in particular from 0.1 to 5.0% by weight.

[0489] (e) from 0 to 1% by weight, in particular from 0.001 to 1% by weight of a chosen compound among monomers and oligomers having a degree of polymerization less than or equal to 3, and organic stabilizers,

[0490] (f) from 0 to 50% by weight of fibers and / or fillers,

[0491] (g) from 0 to 2% by weight of pollutants, in particular from 0.001 to 1%, in particular of 0.001 to 0.1%,

[0492] the sum of components (a) to (g) being equal to 100% and the sum of the constituents volatiles (b), (e) and pollutants (g) being comprised from 0 to 4% by weight, relative to the total weight of said composition C2, in particular from 0.001 to 3%, in particular from 0.001 to 2.1%.

[0493] In a third variant, said composition C2 comprises by weight:

[0494] (a) from 30% to 99.9% of polyamide, in particular from 50 to 99.989%, in particular of 75% to 99.988% by weight,

[0495] (b) from 0 to 1% of plasticizer, in particular from 0.001 to 1% by weight,

[0496] (c) from 0 to 30% of impact modifiers, in particular from 1 to 15.0% by weight,

[0497] (d) from 0.1 to 5.0% by weight of additives,

[0498] (e) from 0 to 1% by weight, in particular from 0.001 to 1% by weight of a chosen compound among monomers and oligomers having a degree of polymerization less than or equal to 3, and organic stabilizers,

[0499] (f) from 0 to 50% by weight of fibers and / or fillers,

[0500] (g) from 0 to 2% by weight of pollutants, in particular from 0.001 to 1%, in particular of 0.001 to 0.1%,

[0501] the sum of components (a) to (g) being equal to 100% and the sum of the constituents volatiles (b), (e) and pollutants (g) being comprised from 0 to 4% by weight, relative to the total weight of said composition C2, in particular from 0.001 to 3%, in particular from 0.001 to 2.1%.

[0502] In a fourth variant, said composition C2 comprises by weight:

[0503] (a) from 30% to 99.999% of polyamide, in particular from 50 to 99.998%, in particular of 75% to 98.997% by weight,

[0504] (b) from 0 to 1% of plasticizer, in particular from 0.001 to 1% by weight,

[0505] (c) from 0 to 30% of impact modifiers, in particular from 1 to 15.0% by weight.

[0506] (d) from 0 to 5% of additives, in particular from 0.1 to 5.0% by weight of additives.

[0507] (e) from 0.001 to 1% by weight of a compound selected from monomers and oligomers having a degree of polymerization less than or equal to 3, and organic stabilizers,

[0508] (f) from 0 to 50% by weight of fibers and / or fillers

[0509] (g) from 0 to 2% by weight of pollutants, in particular from 0.001 to 1%, in particular of 0.001 to 0.1%,

[0510] the sum of components (a) to (g) being equal to 100% and the sum of the constituents volatiles (b), (e) and pollutants (g) being comprised from 0.001 to 4% by weight, relative to the total weight of said composition C2, in particular from 0.002 to 3%, in particular from 0.003 to 2.1%.

[0511] In a fifth variant, said composition C2 comprises by weight:

[0512] (a) from 30% to 99.999% of polyamide, in particular from 50 to 99.998%, in particular of 75% to 98.997% by weight,

[0513] (b) from 0 to 1% of plasticizer, in particular from 0.001 to 1% by weight,

[0514] (c) from 0 to 30% of impact modifiers, in particular from 1 to 15.0% by weight.

[0515] (d) from 0 to 5% of additives, in particular from 0.1 to 5.0% by weight of additives.

[0516] (e) from 0 to 1% by weight, in particular from 0.001 to 1% by weight of a chosen compound among monomers and oligomers having a degree of polymerization less than or equal to 3, and organic stabilizers,

[0517] (f) from 0 to 50% by weight of fibers and / or fillers

[0518] (g) from 0.001 to 1% by weight of pollutants, in particular from 0.001 to 0.1%,

[0519] the sum of components (a) to (g) being equal to 100% and the sum of volatile constituents (b), (e) and pollutants (g) being comprised from 0.001 to 4% by weight, relative to the total weight of said composition C2, in particular from 0.002 to 3%, in particular from 0.003 to 2.1%.

[0520] In a sixth variant, said composition C2 comprises by weight:

[0521] (a) from 30% to 99.998% of polyamide, in particular from 50 to 99.997%, in particular of 75% to 98.997% by weight,

[0522] (b) from 0.001 to 1% by weight of plasticizer,

[0523] (c) from 0 to 30% of impact modifiers, in particular from 1 to 15.0% by weight.

[0524] (d) from 0 to 5% of additives, in particular from 0.1 to 5.0% by weight of additives.

[0525] (e) from 0 to 1% by weight, in particular from 0.001 to 1% by weight of a chosen compound among monomers and oligomers having a lower degree of polymerization or equal to 3, and organic stabilizers,

[0526] (f) from 0 to 50% by weight of fibers and / or fillers

[0527] (g) from 0.001 to 1% by weight of pollutants, in particular from 0.001 to 0.1%,

[0528] the sum of components (a) to (g) being equal to 100% and the sum of volatile constituents (b), (e) and pollutants (g) being from 0.002 to 4% by weight, relative to the total weight of said composition C2, in particular from 0.002 to 3%, in particular from 0.003 to 2.1%.

[0529] In a seventh variant, said composition C2 comprises by weight:

[0530] (a) from 30% to 99.998% of polyamide, in particular from 50 to 99.997%, in particular of 75% to 98.997% by weight,

[0531] (b) from 0 to 1% of plasticizer, in particular from 0.001 to 1% by weight,

[0532] (c) from 0 to 30% of impact modifiers, in particular from 1 to 15.0% by weight.

[0533] (d) from 0 to 5% of additives, in particular from 0.1 to 5.0% by weight of additives.

[0534] (e) from 0.001 to 1% by weight of a compound selected from monomers and oligomers having a degree of polymerization less than or equal to 3, and organic stabilizers,

[0535] (f) from 0 to 50% by weight of fibers and / or fillers

[0536] (g) from 0.001 to 1% by weight of pollutants, in particular from 0.001 to 0.1%,

[0537] the sum of components (a) to (g) being equal to 100% and the sum of volatile constituents (b), (e) and pollutants (g) being comprised from 0.002 to 3% by weight, relative to the total weight of said composition C2, in particular from 0.003 to 3%, in particular from 0.003 to 2.1%.

[0538] In an eighth variant, said composition C2 comprises by weight:

[0539] (a) from 30% to 99.997% of polyamide, in particular from 50 to 99.997%, in particular of 75% to 98.997% by weight,

[0540] (b) from 0.001 to 1% by weight of plasticizer,

[0541] (c) from 0 to 30% of impact modifiers, in particular from 1 to 15.0% by weight.

[0542] (d) from 0 to 5% of additives, in particular from 0.1 to 5.0% by weight of additives.

[0543] (e) from 0.001 to 1% by weight of a compound selected from monomers and oligomers having a degree of polymerization less than or equal to 3, and organic stabilizers,

[0544] (f) from 0 to 50% by weight of fibers and / or fillers

[0545] (g) from 0.001 to 1% by weight of pollutants, in particular from 0.001 to 0.1%,

[0546] the sum of components (a) to (g) being equal to 100% and the sum of volatile constituents (b), (e) and pollutants (g) being from 0.003 to 3% by weight, relative to the total weight of said composition C2, in particular from 0.003 to 2.1%.

[0547] In one embodiment, said composition C2 consists of, by weight:

[0548] (a) from 30 to 100% of polyamide, in particular from 50 to 99.999% by weight, in particular from 75% to 99.998% by weight,

[0549] (b) from 0 to 1% of plasticizer, in particular from 0.001 to 1% by weight,

[0550] (c) from 0 to 30% of impact modifiers, in particular from 1 to 15.0% by weight,

[0551] (d) from 0 to 5% of additives, in particular from 0.1 to 5.0% by weight,

[0552] (e) from 0 to 1% by weight, in particular from 0.001 to 1% by weight of a chosen compound among monomers and oligomers having a degree of polymerization less than or equal to 3, and organic stabilizers,

[0553] (f) from 0 to 50% by weight of fibers and / or fillers,

[0554] (g) from 0 to 2% by weight of pollutants, in particular from 0.001 to 1%, in particular of 0.001 to 0.1%,

[0555] the sum of components (a) to (g) being equal to 100% and the sum of volatile constituents (b), (e) and pollutants (g) being from 0 to 4% by weight, relative to the total weight of said composition C2, in particular from 0.001 to 3%, in particular from 0.001 to 2.1%.

[0556] In a first variant of this embodiment, said composition C2 consists of, by weight:

[0557] (a) from 30% to 99.999% of polyamide, in particular from 50 to 99.998%, in particular of 75% to 99.997% by weight,

[0558] (b) from 0.001 to 1% by weight of plasticizer,

[0559] (c) from 0 to 30% of impact modifiers, in particular from 1 to 15.0% by weight,

[0560] (d) from 0 to 5% of additives, in particular from 0.1 to 5.0% by weight,

[0561] (e) from 0 to 1% by weight, in particular from 0.001 to 1% by weight of a chosen compound among monomers and oligomers having a degree of polymerization less than or equal to 3, and organic stabilizers,

[0562] (f) from 0 to 50% by weight of fibers and / or fillers,

[0563] (g) from 0 to 2% by weight of pollutants, in particular from 0.001 to 1%, in particular of 0.001 to 0.1%,

[0564] the sum of components (a) to (g) being equal to 100% and the sum of the constituents volatiles (b), (e) and pollutants (g) being comprised from 0.001 to 4% by weight, relative to the total weight of said composition C2, in particular from 0.002 to 3%, in particular from 0.002 to 2.1%.

[0565] In a second variant of this embodiment, said composition C2 consists of, by weight:

[0566] (a) from 30% to 99% of polyamide, in particular from 50 to 98.999%, in particular from 75% at 98.998% by weight,

[0567] (b) from 0 to 1% of plasticizer, in particular from 0.001 to 1% by weight,

[0568] (c) from 1 to 15.0% by weight of impact modifiers,

[0569] (d) from 0 to 5% of additives, in particular from 0.1 to 5.0% by weight.

[0570] (e) from 0 to 1% by weight, in particular from 0.001 to 1% by weight of a chosen compound among monomers and oligomers having a degree of polymerization less than or equal to 3, and organic stabilizers,

[0571] (f) from 0 to 50% by weight of fibers and / or fillers,

[0572] (g) from 0 to 2% by weight of pollutants, in particular from 0.001 to 1%, in particular of 0.001 to 0.1%,

[0573] the sum of components (a) to (g) being equal to 100% and the sum of the constituents volatiles (b), (e) and pollutants (g) being comprised from 0 to 4% by weight, relative to the total weight of said composition C2, in particular from 0.001 to 3%, in particular from 0.001 to 2.1%.

[0574] In a third variant of this embodiment, said composition C2 consists of, by weight:

[0575] (a) from 30% to 99.9% of polyamide, in particular from 50 to 99.989%, in particular of 75% to 99.988% by weight,

[0576] (b) from 0 to 1% of plasticizer, in particular from 0.001 to 1% by weight,

[0577] (c) from 0 to 30% of impact modifiers, in particular from 1 to 15.0% by weight,

[0578] (d) from 0.1 to 5.0% by weight of additives,

[0579] (e) from 0 to 1% by weight, in particular from 0.001 to 1% by weight of a chosen compound among monomers and oligomers having a degree of polymerization less than or equal to 3, and organic stabilizers,

[0580] (f) from 0 to 50% by weight of fibers and / or fillers,

[0581] (g) from 0 to 2% by weight of pollutants, in particular from 0.001 to 1%, in particular of 0.001 to 0.1%,

[0582] the sum of components (a) to (g) being equal to 100% and the sum of the constituents volatiles (b), (e) and pollutants (g) being comprised from 0 to 4% by weight, relative to the total weight of said composition C2, in particular from 0.001 to 3%, in particular from 0.001 to 2.1%.

[0583] In a fourth variant of this embodiment, said composition C2 consists of, by weight:

[0584] (a) from 30% to 99.999% of polyamide, in particular from 50 to 99.998%, in particular of 75% to 98.997% by weight,

[0585] (b) from 0 to 1% of plasticizer, in particular from 0.001 to 1% by weight,

[0586] (c) from 0 to 30% of impact modifiers, in particular from 1 to 15.0% by weight.

[0587] (d) from 0 to 5% of additives, in particular from 0.1 to 5.0% by weight of additives.

[0588] (e) from 0.001 to 1% by weight of a compound selected from monomers and oligomers having a degree of polymerization less than or equal to 3, and organic stabilizers,

[0589] (f) from 0 to 50% by weight of fibers and / or fillers

[0590] (g) from 0 to 2% by weight of pollutants, in particular from 0.001 to 1%, in particular of 0.001 to 0.1%,

[0591] the sum of components (a) to (g) being equal to 100% and the sum of volatile constituents (b), (e) and pollutants (g) being from 0.001 to 4% by weight, relative to the total weight of said composition C2, in particular from 0.002 to 3%, in particular from 0.003 to 2.1%.

[0592] In a fifth variant of this embodiment, said composition C2 consists of, by weight:

[0593] (a) from 30% to 99.999% of polyamide, in particular from 50 to 99.998%, in particular of 75% to 98.997% by weight,

[0594] (b) from 0 to 1% of plasticizer, in particular from 0.001 to 1% by weight,

[0595] (c) from 0 to 30% of impact modifiers, in particular from 1 to 15.0% by weight.

[0596] (d) from 0 to 5% of additives, in particular from 0.1 to 5.0% by weight of additives.

[0597] (e) from 0 to 1% by weight, in particular from 0.001 to 1% by weight of a chosen compound among monomers and oligomers having a degree of polymerization less than or equal to 3, and organic stabilizers,

[0598] (f) from 0 to 50% by weight of fibers and / or fillers

[0599] (g) from 0.001 to 1% by weight of pollutants, in particular from 0.001 to 0.1%,

[0600] the sum of components (a) to (g) being equal to 100% and the sum of volatile constituents (b), (e) and pollutants (g) being from 0.001 to 4% by weight, relative to the total weight of said composition C2, in particular from 0.002 to 3%, in particular from 0.003 to 2.1%.

[0601] In a sixth variant of this embodiment, said composition C2 consists of, by weight:

[0602] (a) from 30% to 99.998% of polyamide, in particular from 50 to 99.997%, in particular of 75% to 98.997% by weight,

[0603] (b) from 0.001 to 1% by weight of plasticizer,

[0604] (c) from 0 to 30% of impact modifiers, in particular from 1 to 15.0% by weight.

[0605] (d) from 0 to 5% of additives, in particular from 0.1 to 5.0% by weight of additives.

[0606] (e) from 0 to 1% by weight, in particular from 0.001 to 1% by weight of a chosen compound among monomers and oligomers having a degree of polymerization less than or equal to 3, and organic stabilizers,

[0607] (f) from 0 to 50% by weight of fibers and / or fillers

[0608] (g) from 0.001 to 1% by weight of pollutants, in particular from 0.001 to 0.1%,

[0609] the sum of components (a) to (g) being equal to 100% and the sum of volatile constituents (b), (e) and pollutants (g) being comprised from 0.002 to 4% by weight, relative to the total weight of said composition C2, in particular from 0.002 to 3%, in particular from 0.003 to 2.1%.

[0610] In a seventh variant of this embodiment, said composition C2 consists of, by weight:

[0611] (a) from 30% to 99.998% of polyamide, in particular from 50 to 99.997%, in particular of 75% to 98.997% by weight,

[0612] (b) from 0 to 1% of plasticizer, in particular from 0.001 to 1% by weight,

[0613] (c) from 0 to 30% of impact modifiers, in particular from 1 to 15.0% by weight.

[0614] (d) from 0 to 5% of additives, in particular from 0.1 to 5.0% by weight of additives.

[0615] (e) from 0.001 to 1% by weight of a compound selected from monomers and oligomers having a degree of polymerization less than or equal to 3, and organic stabilizers,

[0616] (f) from 0 to 50% by weight of fibers and / or fillers

[0617] (g) from 0.001 to 1% by weight of pollutants, in particular from 0.001 to 0.1%,

[0618] the sum of components (a) to (g) being equal to 100% and the sum of volatile constituents (b), (e) and pollutants (g) being comprised from 0.002 to 3% by weight, relative to the total weight of said composition C2, in particular from 0.003 to 3%, in particular from 0.003 to 2.1%.

[0619] In an eighth variant of this embodiment, said composition C2 consists of, by weight:

[0620] (a) from 30% to 99.997% of polyamide, in particular from 50 to 99.997%, in particular of 75% to 98.997% by weight,

[0621] (b) from 0.001 to 1% by weight of plasticizer,

[0622] (c) from 0 to 30% of impact modifiers, in particular from 1 to 15.0% by weight.

[0623] (d) from 0 to 5% of additives, in particular from 0.1 to 5.0% by weight of additives.

[0624] (e) from 0.001 to 1% by weight of a compound selected from monomers and oligomers having a degree of polymerization less than or equal to 3, and organic stabilizers,

[0625] (f) from 0 to 50% by weight of fibers and / or fillers

[0626] (g) from 0.001 to 1% by weight of pollutants, in particular from 0.001 to 0.1%,

[0627] the sum of components (a) to (g) being equal to 100% and the sum of volatile constituents (b), (e) and pollutants (g) being comprised from 0.003 to 3% by weight, relative to the total weight of said composition C2, in particular from 0.003 to 2.1%.

[0628] In particular, the proportion by weight of pollutants in said composition C2 and in all the variants defined above is less than 10 ppm, in particular less than 1 ppm relative to the total weight of composition C2.

[0629] The definition of components (a) to (g) is the same as for composition Cl. Description of figures

[0630] [Fig. 1] shows a scraped film thin film evaporator. [0631 ] ( 1 ) Rotor control.

[0632] (2) Upper level

[0633] (3) Separator

[0634] (4) Feeding at the distributor ring

[0635] (5) Heating steam

[0636] (6) Rotor

[0637] (7) Lower landing

[0638] (8) Concentrate

[0639] (9) Condensed

[0640] (10) Steam or distillate

[0641] EXAMPLES

[0642] The present invention will now be illustrated by examples without being limited thereto.

[0643] Example 1: Recycling of polyamide 12 from offshore pipes after use in a scraped film thin-film evaporator without chain limiter

[0644] The polyamide product to be recycled is a sheath constituting one of the layers of the offshore pipe after use. This sheath was prepared according to the single-layer tube extrusion process known to those skilled in the art. The composition of this polyamide sheath is a polyamide 12 containing 12% BBSA plasticizer, less than 0.2% monomer and oligomers having a degree of polymerization less than or equal to 3, 1.2% non-volatile additives and 5.1% pollutants (oil and extraction additives).

[0645] The other layers of the offshore pipe are composed of metal sheaths. After recovery of the offshore pipe after use for the extraction of oil under the sea for 12 years, a separation step consisting of cutting the pipe in two lengthwise allows the recovery of the polyamide 12 sheath (step a). This sheath is then crushed to obtain a ground material with a size of approximately 6 mm (step b).

[0646] Step c) then consists of introducing said polyamide 12 recovered in step b) into a single-screw extruder with a diameter of 90 mm heated to 280°C in order to melt the polymer.

[0647] Step d) consists of introducing the molten product obtained in step c) into a scraped film thin-film evaporator having a degassing surface area of ​​2 m2, at a flow rate of 70 kg / h. The scraped film thin-film evaporator is heated to a temperature of 280°C.

[0648] Step e) consists of distributing in the form of a thin film of 0.5 mm on the walls of said system by means of a rotor rotating at 200 revolutions per minute with degassing under reduced pressure of 10 hPa. The pollutants (oil and its extraction additives), the plasticizer and the oligomers and monomers are recovered in a trap located after the outlet (10) between the evaporator and the vacuum pump by condensation vapors. The degassing surface is therefore in this example 28571 mm2 / kg / h.

[0649] Step f) consists of the recovery of polyamide 12 in solid form by granulation of the molten polyamide by the underwater granulation process known to those skilled in the art.

[0650] Example 2 (comparative): recycling of polyamide 12 from offshore pipes after use in a co-rotating twin-screw extruder without chain limiter

[0651] The polyamide product to be recycled is a sheath constituting one of the layers of the offshore pipe after use. This sheath was prepared according to the single-layer tube extrusion process known to those skilled in the art. The composition of this polyamide sheath is a polyamide 12 containing 12% BBSA plasticizer, less than 0.2% monomer and oligomers having a degree of polymerization less than or equal to 3, 1.2% non-volatile additives and 5.1% pollutant (oil and additives).

[0652] The other layers of the offshore pipe are composed of metal sheaths. After recovery of the offshore pipe after use for the extraction of oil under the sea for 12 years, a separation step consisting of cutting the pipe in two lengthwise allows the polyamide 12 sheath to be recovered (step a). This sheath is then crushed to obtain a ground material with a size of approximately 6 mm (step b).

[0653] Step c) then consists of introducing said polyamide 12 recovered in step b) into a ZSK40 co-rotating twin-screw extruder from the company Coperion.

[0654] Step d) consists of extrusion at 70 kg / h and for a temperature of 280°C with degassing under reduced pressure of 10 hPa. The plasticizer and the oligomers and monomers are recovered in a trap located between the extruder and the vacuum pump by condensation of the vapors. The degassing zone consists of 2 screws with a diameter of 40 mm for a length of 12 times the diameter, i.e. 480 mm. The degassing surface per unit of flow rate is therefore in this example 1723 mm2 / kg / h.

[0655] Step e) does not exist.

[0656] Step f) consists of the recovery of polyamide 12 in solid form by granulation of the molten polyamide by the underwater granulation process known to those skilled in the art.

[0657] Example 3: Recycling of polyamide 11 from offshore pipes after use in a scraped film thin-film evaporator with chain limiter (adipic acid)

[0658] The polyamide product to be recycled is a sheath constituting one of the layers of the offshore pipe after use. This sheath was prepared according to the single-layer tube extrusion process known to those skilled in the art. The composition of this polyamide sheath is a polyamide 11 containing 12% BBSA plasticizer, less than 0.2% monomer and oligomers having a degree of polymerization less than or equal to 3, 800 ppm catalyst, 1.2% non-volatile additives and 5.1% pollutants (oil and additives).

[0659] The other layers of the offshore pipe are composed of metal sheaths. After recovery of the offshore pipe after use for the extraction of oil under the sea for 12 years, a separation step consisting of cutting the pipe in two lengthwise allows the polyamide 11 sheath to be recovered (step a). This sheath is then crushed to obtain a ground material with a size of approximately 6 mm (step b).

[0660] Step c) then consists of introducing said polyamide 11 recovered in step b) with the addition of 1% of adipic acid into a single-screw extruder with a diameter of 90 mm heated to 280°C in order to melt the polymer.

[0661] Step d) consists of introducing the molten product obtained in step c) into a scraped film thin-film evaporator having a degassing surface area of ​​2 m2, at a flow rate of 70 kg / h. The scraped film thin-film evaporator is heated to a temperature of 280°C.

[0662] Step e) consists of distributing in the form of a thin film of 0.5 mm on the walls of said system by means of a rotor rotating at 200 revolutions per minute with degassing under reduced pressure of 10 hPa. The plasticizer and the oligomers and monomers are recovered in a trap located after the outlet (10) between the evaporator and the vacuum pump by condensation of the vapors. The degassing surface is in this example 28571 mm2 / kg / h.

[0663] Step f) consists of the recovery of polyamide 11 in solid form by granulation of the molten polyamide by the underwater granulation process known to those skilled in the art.

[0664] Example 4: Recycling of impact-modified polyamide 11 from offshore pipes after use in a scraped film thin-film evaporator with chain limiter (adipic acid)

[0665] The polyamide product to be recycled is a sheath constituting one of the layers of the offshore pipe before use. This sheath was prepared according to the single-layer tube extrusion process known to those skilled in the art. The composition of this polyamide sheath is a polyamide 11, 10% of an impact modifier, less than 0.2% of monomer and oligomers having a degree of polymerization less than or equal to 3, 800 ppm of catalyst and 1.2% of non-volatile additives and 5.1% of pollutants (oil and extraction additives).

[0666] The other layers of the offshore pipe are composed of metal sheaths. After recovery of the offshore pipe after use for the extraction of oil under the sea for 12 years, a separation step consisting of cutting the pipe in two lengthwise allows the polyamide 11 sheath to be recovered (step a). This sheath is then crushed to obtain a ground material with a size of approximately 6 mm (step b).

[0667] Step c) then consists of the introduction of said polyamide 11 recovered in step b) with the addition of 1% adipic acid in a 90 mm diameter single-screw extruder heated to 280°C in order to melt the polymer.

[0668] Step d) consists of introducing the molten product obtained in step c) into a scraped film thin-film evaporator having a degassing surface area of ​​2 m2, at a flow rate of 70 kg / h. The scraped film thin-film evaporator is heated to a temperature of 280°C.

[0669] Step e) consists of distributing in the form of a thin film of 0.5 mm on the walls of said system by means of a rotor rotating at 200 revolutions per minute with degassing under reduced pressure of 10 hPa. The plasticizer and the oligomers and monomers are recovered in a trap located after the outlet (10) between the evaporator and the vacuum pump by condensation of the vapors. The degassing surface is in this example 28571 mm2 / kg / h.

[0670] Step f) consists of the recovery of polyamide 11 in solid form by granulation of the molten polyamide by the underwater granulation process known to those skilled in the art.

[0671] Example 5: Recycling of polyamide 12 loaded from offshore pipes after use in a scraped film thin film evaporator without chain limiter

[0672] The recycling process is as defined for Example 1.

[0673] The filler corresponds to 20% by weight relative to the total weight of the composition of the polyamide sheath.

[0674] Example 6: Recycling of polyamide 11 from used fuel pipes in a scraped film thin-film evaporator with chain limiter (adipic acid)

[0675] The polyamide product to be recycled is in the form of a single-layer polyamide pipe produced for 10 years in a car (Toyota brand). The composition of the layer in contact with the gasoline of these polyamide pipes is a polyamide 11 containing less than 0.2% of monomer and oligomers having a degree of polymerization less than or equal to 3, 800 ppm of catalyst and 1.2% of non-volatile additives and 2.4% of gasoline.

[0676] These pipes are crushed without a prior step (to be confirmed) to obtain a crushed material of a size of approximately 6 mm (step b).

[0677] Step c) then consists of introducing said polyamide 11 recovered in step b) with the addition of 1% of adipic acid into a single-screw extruder with a diameter of 90 mm heated to 280°C in order to melt the polymer.

[0678] Step d) consists of introducing the molten product obtained in step c) into a scraped film thin-film evaporator having a degassing surface area of ​​2 m2, at a flow rate of 70 kg / h. The scraped film thin-film evaporator is heated to a temperature of 280°C.

[0679] Step e) consists of distributing in the form of a thin film of 0.5 mm on the walls of said system by means of a rotor rotating at 200 revolutions per minute with degassing under reduced pressure of 10 hPa. The plasticizer and the oligomers and monomers are recovered in a trap located after the outlet (10) between the evaporator and the vacuum pump by condensation of the vapors. The degassing surface in this example is 28571 mm2 / kg / h.

[0680] Step f) consists of the recovery of polyamide 11 in solid form by granulation of the molten polyamide by the underwater granulation process known to those skilled in the art.

[0681] Example 7: Recycling of polyamide 11 from used coolant pipe in a scraped film thin-film evaporator with chain limiter (adipic acid)

[0682] The polyamide product to be recycled is in the form of polyamide pipe products used for 10 years in a car (Toyota brand). The composition of the internal layer in contact with the coolant of these polyamide pipes is a polyamide 11 containing less than 0.2% of monomer and oligomers having a degree of polymerization less than or equal to 3, 800 ppm of catalyst and 1.2% of non-volatile additives and 2.4% of coolant.

[0683] These pipes are ground without a prior step to obtain a ground material of a size of approximately 6 mm (step b).

[0684] Step c) then consists of introducing said polyamide 11 recovered in step b) with the addition of 1% of adipic acid into a single-screw extruder with a diameter of 90 mm heated to 280°C in order to melt the polymer.

[0685] Step d) consists of introducing the molten product obtained in step c) into a scraped film thin-film evaporator having a degassing surface area of ​​2 m2, at a flow rate of 70 kg / h. The scraped film thin-film evaporator is heated to a temperature of 280°C.

[0686] Step e) consists of distributing in the form of a thin film of 0.5 mm on the walls of said system by means of a rotor rotating at 200 revolutions per minute with degassing under reduced pressure of 10 hPa. The plasticizer and the oligomers and monomers are recovered in a trap located after the outlet (10) between the evaporator and the vacuum pump by condensation of the vapors. The degassing surface is in this example 28571 mm2 / kg / h.

[0687] Step e) consists of recovering the polyamide 11 in solid form by granulation of the molten polyamide using the underwater granulation process known to those skilled in the art.

[0688] The initial compositions C1 for preparing the offshore pipes, purge blocks, injected parts and hydrogen tank of the above examples are as follows (by weight):

[0689] [Tables 1] Product Part to be recycled PA % Cat. % Pol. Plast. % Mono . and oligo. % IM % Filler (Carbon Black e Ensaco ) % Non-volatile additives (CuI / KI) % Cl Example 1 Offshore pipe 84.80 0 5.1 12 <0.2 0 0 1.2 Cl Example 2 (comparative) Offshore pipe 84.80 0 5.1 12 <0.2 0 0 1.2 Cl Example 3 Offshore pipe 84.72 0.08 5.1 12 <0.2 0 0 1.2 Cl Example 4 Offshore pipe 74.72 0.08 5.1 0 <0.2 10 0 1.2 Cl Example 5 Offshore pipe 64.80 0 3.2 12 <0.2 0 20 1.2 Cl Example 6 Gasoline pipe 84.72 0.08 2.8 0 <0.2 0 0 1.2 Cl Example 7 Coolant pipe 84.72 0.08 2.4 0 <0.2 0 0 1.2

[0690] PA means polyamide.

[0691] Cat. means catalyst and is phosphoric acid.

[0692] Plast. means plasticizer and is BBSA (N-Butyl Benzene Sulfonamide), marketed by Partners in Chemical.

[0693] IM stands for impact modifier and is EXXELOR® VA 1801, marketed by Vanderbilt Chemicals, LLC.

[0694] Pol. means pollutants

[0695] The filler is Ensaco® Carbon Black and is marketed by Imerys.

[0696] After treatment by a scraped film thin-film evaporator under different conditions in the presence or absence of adipic acid, the level of pollutants remaining in the final C2 compositions obtained is determined according to an ATG protocol according to the ISO 11358:2022 standard under a reduced pressure of 1000 Pa by coupling the ATG to an infrared spectroscopy device and is indicated in the following table 2 (by weight):

[0697] [Tables2] Product Rate of pollutants remaining in the compositions C2 C2 from Cl of example 1 <2% C2 from Cl of example 2 (comparative) >3% C2 from Cl of example 3 <2% C2 from Cl of example 4 <2% C2 from Cl of example 5 <2% C2 from Cl of example 6 <2% C2 from Cl of example 7 <2%

[0698] Table 2 shows that the proportion of volatiles and pollutants remaining in the different compositions C2 resulting from compositions C1 according to examples 1 and 3 to 7 originating from different products after recycling according to the invention is less than 2% by weight relative to the total weight of composition C2, unlike the proportion of volatiles remaining in the different compositions C2 resulting from compositions C1 according to example 2 originating from different products after recycling with a “conventional” extruder which is greater than 3% by weight relative to the total weight of said composition C2.

Claims

Claims

1. A method for recycling a polyamide, said polyamide originating from at least one product consisting of one or more elements comprising an initial composition Cl comprising a polyamide, pollutants originating from the use of said product and one or more volatile and non-volatile constituent(s) originally present in said product before its use, said product being obtained during or after the processing of said composition by extrusion, by extrusion-blow molding, by rotational molding, by injection or by 3D printing, the initial proportion of said pollutants being from 0.1 to 20% by weight relative to the total weight of said composition, in particular from 0.5 to 15%, in particular from 0.5 to 10%, more particularly from 0.5 to 5%, characterized in that it comprises the following steps: a) Optionally pre-treatment of said product to separate the element comprising said composition from other elements not recyclable with said process and present in said product, b) Optionally shaping of said untreated product or of said element separated in step a) to be able to be introduced into a system capable of melting and transporting a polymer continuously, c) introduction of said untreated product and optionally shaped in step b) or of said element separated from step a) and optionally shaped in step b) into a system capable of melting, in particular an extruder, at a temperature higher than the Tf of said polyamide if it is semi-crystalline or higher than the Tg of said polyamide if it is amorphous, d) introduction of said molten product obtained in step c) into a system capable of transporting a polymer continuously and having a degassing surface, in particular under reduced pressure,in particular said system is a thin-film evaporator, e) distribution in the form of a thin film on the walls of said system by means of a rotor with degassing, in particular under reduced pressure, continuously of said molten product of step d) to reduce or eliminate said pollutants and said one or more volatile constituent(s), f) obtaining a final composition C2 of molten polyamide and then putting it in the form of powder, ground material, granules or a new extruded part, said final shaped composition having a, proportion by weight of said pollutants lower than the initial proportion present in said initial composition Cl, in particular <2%, in particular <1%, advantageously <0.5% by weight relative to the total weight of composition C2.

2. Method according to claim 1, characterized in that said product is chosen from a single-layer or multi-layer structure obtained by extrusion, extrusion-blow molding, rotational molding or injection, a production start product of said structure, an end-of-production product of said structure and a production scrap of said structure.

3. Method according to claim 1 or 2, characterized in that the degassing of step e) is carried out under reduced pressure for a time greater than or equal to 1 min, in particular from 1 to 5 min.

4. Method according to one of claims 1 to 3, characterized in that said degassing surface is > 5000 mm2 / kg / h.

5. Method according to one of claims 1 to 4, characterized in that the degassing flow rate is > 100 kg / h, in particular > 150 kg / h.

6. Method according to one of claims 1 to 5, characterized in that the reduced pressure is from 0.1 hPa to 40 hPa, in particular from 0.5 hPa to 25 hPa.

7. Method according to one of claims 1 to 6, characterized in that said pollutants and said constituents are eliminated to at least 60% by weight relative to the total weight of the pollutants / constituents present in said product or said polyamide, in particular to at least 70%, in particular to at least 80%, in particular to at least 85%, more particularly to at least 90%, even more particularly to at least 95%.

8. Method according to one of claims 1 to 7, characterized in that said pollutants and said constituents are volatile compounds at reduced pressure, in particular at atmospheric pressure.

9. Method according to claim 8, characterized in that said volatile compounds are chosen from the fluids transported by said structure, a plasticizer, a monomer and an oligomer having a degree of polymerization less than or equal to 3, an organic stabilizer and a mixture thereof.

10. Method according to one of claims 2 to 8, characterized in that said polyamide of said structure before its use has a catalyst content by weight of from 0 to 9000, in particular from 0 to 6000 ppm, preferably from 0 to 3400 ppm, advantageously from 0 to 1000 ppm relative to the total weight of the polyamide or of the composition comprising or constituting it.

11. Method according to one of claims 1 to 10, characterized in that at least one component chosen from molecules comprising one or more carboxylic acid functions, one or more primary amine functions, one or more alcohol functions and one or more ester functions or a mixture thereof is added in step c).

12. Method according to claim 11, characterized in that said component is chosen from molecules comprising one or more carboxylic acid and primary amine functions.

13. Method according to claim 11 or 12, characterized in that a single molecule is added whose functionality is between 1 and 3.

14. Method according to claim 11 or 12, characterized in that several molecules are added whose average functionality is between 1.8 and 2.

2.

15. Method according to claim 11 or 12, characterized in that several molecules are added whose average functionality is between 0.8 and 1.

2.

16. Method according to one of claims 11 to 15, characterized in that the proportion of said added component is from 0.01% to 10% by weight relative to the total weight of said shaped product or of said separated shaped polyamide from step b).

17. Method according to one of claims 1 to 16, characterized in that the polyamide of the final composition obtained in step f) after shaping in the form of granules or a new extruded part has an NH2 / COOH ratio of from 0.75 to 1.25, in particular from 0.92 to 1.08, preferably from 0.95 to 1.05, advantageously from 0.98 to 1.02, in particular from 0.99 to 1.

01.

18. Method according to one of claims 1 to 17, characterized in that said structure is chosen from a pipe, a granule, a film, a sheet, a sheath, a reservoir, a hollow body, and their mixtures.

19. Method according to claim 18, characterized in that said structure is a fluid transport pipe for an automobile.

20. Method according to claim 18, characterized in that said structure is an oil or gas field exploitation pipe, underwater or on land.

21. Method according to one of claims 1 to 20, characterized in that said polyamide is a semi-crystalline polyamide, especially semi-crystalline aliphatic.

22. Initial composition comprising one or more volatile or non-volatile constituent(s) before use, as defined in one of claims 1 to 21, said composition being called Cl and comprising by weight: (a) from 30 to 99.9% of polyamide, in particular from 50 to 99.5% by weight, in particular from 75% to 99.5% by weight, (b) from 0 to 15% of plasticizer, in particular from 0.1 to 15.0% by weight, (c) from 0 to 30% of impact modifiers, in particular from 1 to 15.0% by weight, (d) from 0 to 5% of additives, in particular from 0.1 to 5.0% by weight, (e) from 0 to 6% by weight, in particular from 0.1 to 5%, in particular from 1 to 4% by weight of a compound chosen from monomers and oligomers having a degree of polymerization less than or equal to 3, and organic stabilizers, (f) from 0 to 50% by weight of fibers and / or fillers, (g) 0.1 to 20% by weight of pollutants, in particular from 0.5 to 15%, in particular from 0.5 to 10%, more particularly from 0.5 to 5%, the sum of components (a) to (g) being equal to 100% and the sum of volatile constituents (b), (e) and pollutants (g) being from 0.1 to 41% by weight, relative to the total weight of said composition Cl, in particular from 0.5 to 25%, in particular from 0.5 to 20%.

23. Final composition after recycling of composition Cl defined in claim 22, and called C2, comprising by weight: (a) from 30 to 99.99999% of polyamide, in particular from 50 to 99.9999% by weight, in particular from 75% to 99.9990% by weight, (b) from 0 to 1% of plasticizer, in particular from 0.001 to 1% by weight, (c) from 0 to 30% of impact modifiers, in particular from 1 to 15.0% by weight, (d) from 0 to 5% of additives, in particular from 0.1 to 5.0% by weight, (e) from 0 to 1% by weight, in particular from 0.001 to 1% by weight of a compound chosen from monomers and oligomers having a degree of polymerization less than or equal to 3, and organic stabilizers, (f) from 0 to 50% by weight of fibers and / or fillers, (g) from 0 to 2% by weight of pollutants, in particular from 0.0001 to 1%, in particular from 0.001 to 0.1%, the sum of components (a) to (g) being equal to 100% and the sum of volatile constituents (b), (e) and pollutants (g) being comprised from 0.00001 to 4% by weight, relative to the total weight of said composition C2, in particular from 0.001 to 3%, in particular from 0.001 to 2.1%.

24. Use of the granules obtained in step f. of the process according to one of claims 1 to 21, for the preparation of articles obtained by extrusion.

25. Use according to claim 24, characterized in that the article is a single-layer or multi-layer structure for transporting, distributing or storing fluids.

26. Use according to claim 24, characterized in that said structure is chosen from a fluid transport pipe for an automobile.

27. ​​Use according to claim 24, characterized in that said structure is a pipe for exploiting an oil or gas deposit, underwater or on land.

28. Use of the granules from step f. of the process according to one of claims 1 to 21, for the preparation of articles obtained by injection.

29. Use according to claim 28, characterized in that the article relates to applications in electrical or electronics, in particular electrical and electronic equipment goods, such as encapsulated solenoids, pumps, telephones, computers, printers, fax machines, modems, monitors, remote controls, cameras, circuit breakers, electrical cable sheaths, optical fibers, switches, multimedia systems, or applications in sport, in particular a ski boot or part of a ski boot or a rigid crampon shoe or part of a rigid crampon shoe, such as a football, rugby or American football shoe, a hockey shoe or part of a hockey shoe, or a running shoe, a golf ball or part of a golf ball, or a stick in the sport of lacrosse or a hockey article such as a helmet or sporting articles for the protection of the head, shoulders,elbows, hands, knees, back or shin, such as helmets, gloves, shoulder pads, elbow pads, knee pads or shin guards or optical applications, in particular glasses or a mask, in particular glasses or a mask used in the practice of a sport such as protective glasses or a ski mask.,

Images