Method for depolluting and recycling a polyamide by continuous degassing in the melt state

Abstract

The present invention relates to a method 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 and one or more volatile and non-volatile constituent(s) present originally in said product before its use, the initial proportion of said volatile constituent(s) being from 0.1 to 21% by weight relative to the total weight of said composition, characterized in that it comprises the following steps: a) optionally pre-treating said product, b) optionally shaping said product not treated or said element separated in step a), c) introducing said product not treated and optionally shaped in step b) or said separated element from step a), optionally shaped in step b), into a system capable of melting and transporting a polymer continuously and having a degassing surface, d) extruding with degassing, continuously in the melt state, of said optionally shaped product or of said separated polyamide formed and introduced in step c) at a temperature higher than the Tm of said polyamide if it is semi-crystalline or higher than the Tg of said polyamide if it is amorphous, e) obtaining a final molten polyamide composition C2 and then converting it into the form of a powder, ground material, pellets or a new extruded part, said final shaped composition having a proportion by weight of said volatile constituant(s) lower than the initial proportion present in said initial composition.

Description

[0001] DESCRIPTION

[0002] TITLE: Process for decontamination and recycling of a polyamide by continuous degassing in the molten state

[0003] [Technical field]

[0004] This 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.

[0005] [Earlier technique]

[0006] Polyamides are used, among other things, to manufacture articles for a wide variety of applications such as automotive, offshore and onshore oil exploration, electricity, household appliances, textiles, sports and leisure, food packaging, medical packaging, etc.

[0007] There are two types of waste: post-industrial waste and post-consumer waste.

[0008] When using these polyamides to manufacture said articles, for example by extrusion, extrusion-blow molding, rotational molding or injection, 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.

[0009] It therefore becomes necessary to be able to recycle these unused polyamides.

[0010] Furthermore, this post-industrial polyamide contains plasticizer which must be removed in order to have unplasticized polyamide for other uses, but which must also be recovered for recycling to plasticize a new polyamide.

[0011] There is therefore a need to be able to recycle these unused polyamides.

[0012] 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 comprising a polyamide, 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 volatile constituent(s) being between 0.1 and 21% by weight relative to the total weight of said composition, in particular between 0.5 and 21%, in particular between 0.5 and 14%, characterized in that it comprises the following steps: a) Optionally prior treatment of said product to separate the element comprising said composition from other elements not recyclable with said method and present in said product,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 continuously melting and transporting a polymer, c) introducing said untreated product and optionally shaped in step b) or said separate element from step a) and optionally shaped in step b) into a system capable of continuously melting and transporting a polymer and having a degassing surface, in particular under reduced pressure, in particular said system is an extruder, in particular a multi-screw extruder, in particular a multi-rotational system extruder, d) extruding with degassing, in particular under reduced pressure, continuously in the molten state said optionally shaped product or said separate polyamide shaped and introduced in step c) 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 one or more volatile constituent(s), e) obtaining a final composition of molten polyamide and then forming it into powder, ground material, granules or a new extruded part, said powder, ground material, said final shaped composition having a proportion by weight of said volatile constituent(s) lower than the initial proportion present in said initial composition, in particular <3%, in particular <2%, in particular <1% by weight, relative to the total weight of composition C2.,

[0013] 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, before or after use of said product, or the introduction of an element separated beforehand from said product, before or after use of said product, into a system capable of melting and transporting a polymer continuously and having a degassing surface, then extrusion 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 of polyamide melted and put in the form of powder, ground material, granules or a new extruded part, with a proportion by weight of volatile constituents in the final composition lower than the initial proportion present in said initial composition, in particular <3%, in particular <2%, in particular <1%,relative to the total weight of composition C2.,

[0014] The invention therefore makes it possible to limit or remove said volatile constituent(s) from said initial composition 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.

[0015] The melt viscosity of said polyamide can be measured in plane-plane rheology under 1 Hz and 2% deformation, at a temperature depending on the Tf of said polymer, for example at a temperature between Tf + 10 °C and Tf + 100 °C. 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 molding, injection or 3D printing" designates on the one hand post-industrial waste also called "pre-consumer" waste which refers to the waste generated by the manufacturing process and therefore during the processing of said polyamide by extrusion, extrusion-blow molding, rotational molding, injection or 3D printing. These are therefore typically the purge blocks at the start or end of production as well as the injection sprues or scrap during production.

[0016] 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" can also designate the product obtained after the processing of said polyamide by extrusion, extrusion-blow molding, rotational molding or injection which, although compliant, will never be used for various reasons and which must nevertheless be recycled. This is also "pre-consumer" waste.

[0017] The said expression also 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.

[0018] One of the advantages of the invention is therefore to be able to recycle a polyamide constituting an element of a product and this whatever the moment, namely during the production of said product before its use or after production of said product and after its use and to be able to eliminate or at least reduce the proportion of constituents present in said product and in particular in said polyamide.

[0019] 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 and thus to be able on the one hand to recover said polyamide substantially free of said volatile constituent(s) for another use and on the other hand to recover said volatile constituent(s) for use with another polymer, in particular a polyamide or for another application.

[0020] Throughout the description, all percentages are given by weight unless otherwise specified.

[0021] The proportion of said volatile and non-volatile constituent(s) in said initial composition constituting said element of said product before its use depends on the proportion introduced during its preparation of said initial composition.

[0022] The proportion of said volatile constituent(s) in said final composition C2 can be determined according to an ATG protocol according to standard ISO 11358:2022.

[0023] It is determined using an ATG TA Instrument TGA550 device with an isothermal measurement with the Equilibrate function for one hour under nitrogen at 300°C. 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. A production start-up product of said structure and an end-of-production product of said structure correspond to the purge blocks at the start or end of production.

[0024] Extrusion is a (thermo)mechanical manufacturing process by which a compressed material is forced through a die having the cross-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.

[0025] Extrusion blow molding is a process for shaping thermoplastic polymer materials that is used to manufacture hollow bodies of variable capacity (from a few cm 3 a few meters away 3 ): bottles, flasks, cans, barrels, tanks, etc. This process consists of combining the extrusion technique with that of blowing.

[0026] Rotomolding, or rotational molding, is a process of shaping, particularly hollow objects, by molding plastic materials in a mold in order to reproduce the internal shape of this mold.

[0027] Thermoplastic injection consists of injecting a molten polymer (thermoplastic material) under high pressure into a mold, using an injection press.

[0028] 3D printing or additive manufacturing brings together manufacturing processes that allow the creation of large-volume parts by adding material in successive layers.

[0029] The term "structure" also refers to any form, system or construction that can be obtained by extrusion, extrusion blow molding, rotational molding or injection.

[0030] 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.

[0031] In a first variant of this embodiment, said structure is a structure obtained by extrusion.

[0032] In a first embodiment of this first variant, said structure is a single-layer or multi-layer structure, in particular multi-layer.

[0033] In this first embodiment of this first variant, said structure may be a fluid transport pipe for an automobile.

[0034] Said fluids which will be transported are for example 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. In a second embodiment of this first variant, said structure is an oil or gas field exploitation pipe, underwater or on land.

[0035] Advantageously, said structure is an oil or gas field exploitation pipe, under the sea.

[0036] In a second variant of this embodiment, said structure is a structure obtained by injection.

[0037] In a first embodiment of this second variant, said structure may be an article in the field of sport, industry, electronics and optics.

[0038] In a third variant of this embodiment, said structure is a structure obtained by rotational molding.

[0039] In a first embodiment of this third variant, said structure may be a reservoir or a hollow body.

[0040] In a fourth variant of this embodiment, said structure is a structure obtained by extrusion-blowing.

[0041] In a first embodiment of this fourth variant, said structure may be a reservoir or a hollow body.

[0042] Regarding polyamide to be recycled

[0043] The nomenclature used to define polyamides is described in ISO 1874-1:2011 “Plastics - Polyamide (PA) materials for molding and extrusion - Part 1: Designation”, particularly on page 3 (tables 1 and 2) and is well known to those skilled in the art.

[0044] The polyamide may be a homopolyamide or a copolyamide or a mixture thereof.

[0045] 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.

[0046] 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.

[0047] Mn is measured according to the following protocol: 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 particle size of 7 pm, and a 100 Å column with dimensions of 300 x 8 mm and 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.

[0048] Polyamide can be semi-crystalline or amorphous.

[0049] 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 of 2013 greater than 30 J / g, preferably greater than 35 J / g.

[0050] In one embodiment, the polyamide is semi-crystalline, in particular semi-crystalline aliphatic.

[0051] In one embodiment, the semi-crystalline aliphatic polyamide is linear.

[0052] In one embodiment, the semi-crystalline aliphatic polyamide is a homopolyamide, especially a semi-crystalline linear aliphatic homopolyamide.

[0053] Said semi-crystalline polyamide can be obtained by polycondensation: of at least one C6 to C10 amino acid, preferably C10 to C10, more preferably C10 to C12, or of at least one C6 to C10 lactam, preferably C10 to C10, more preferably C10 to C12, or of at least one aliphatic diamine Ca in C4-C36, preferably C5-C10, preferably C5-C12, more preferably C10-C12, with at least one aliphatic dicarboxylic acid Cb in C4-C36, preferably C6-C10, preferably C8-C12, more preferably C10-C12,;

[0054] 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 Cg to Cig lactam, preferably a Cio to Cig lactam, more preferably a Cio to C12 lactam. A C6 to C12 lactam is in particular caprolactam, decanolactam, undecanolactam, and lauryllactam.

[0055] 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.

[0056] 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.

[0057] 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 C10 amino acid, preferably a C10 to C10 amino acid, more preferably a C10 to C12 amino acid. 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.

[0058] 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.

[0059] 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.

[0060] 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 Cg-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.

[0061] The diamine can be linear or branched. Advantageously, it is linear.

[0062] 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.

[0063] Advantageously, said at least one diamine Ca is C5-C18 and 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.

[0064] 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.

[0065] Advantageously, the diamine Ca used is C10 to C12, in particular chosen from 1,10-decamethylenediamine, 1,11-undecamethylenediamine, 1,12-dodecamethylenediamine. Said at least one dicarboxylic acid Cb in C4 to C36 can 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.

[0066] The diacid can be linear or branched. Advantageously, it is linear.

[0067] Advantageously, said at least one dicarboxylic acid Cb is Cg to Cig 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.

[0068] Advantageously, said at least one dicarboxylic acid Cb is Cg to C12 and is chosen from adipic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid.

[0069] Advantageously, said at least one dicarboxylic acid Cb is C10 to C12 and is chosen from sebacic acid, undecanedioic acid, dodecanedioic acid.

[0070] 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. Advantageously, said aliphatic semi-crystalline polyamide is obtained from the polycondensation of a single diamine Ca with a single dicarboxylic acid Cb.

[0071] In particular, the semi-crystalline polyamide is chosen from: polyamide 11 (PAU), polyamide 12 (PA12), 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 PAU and PA12, in particular PAU.

[0072] More particularly, it is chosen from polyamide 11 (PAU), polyamide 12 (PA12), 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 PAU and PA12, in particular PAU.

[0073] Even more particularly, it is chosen from: 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 PAU and PA12, in particular PAU.

[0074] In particular, it is chosen from: 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 PAU and PA12, in particular PAU.

[0075] An amorphous polyamide within the meaning of the invention designates a polyamide which has only a glass transition temperature (no melting temperature (Tm)), 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 standard ISO 11357-3:2013 is less than 30 J / g, in particular less than 20 J / g, preferably less than 15 J / g.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 aliphatic dicarboxylic acid (Y) in C4-C36, preferably Cg-Cig, preferably C6-C12, more preferably C10-C12 OR 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 C8, preferably C10 to C18, more preferably C10 to C12, or of at least one lactam in C6 to C8, preferably C10 to C18, more preferably C10 to C12, or of at least one diamine Ca in C4-C36, preferably C5-C18, preferably C5-C12, more preferably C10 to C18 ... preferentially C10-C12, with at least one dicarboxylic acid Cb in C4-C36, preferentially C6-C18, preferentially C6-C12, more preferentially C10-C12.

[0076] 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 referred to as (BMACM) or (MACM) (and noted B hereinafter), bis(p-aminocyclohexyl)methane commonly referred to as (PACM) (and noted P hereinafter), in particular Dicykan®, isopropylidenedi(cyclohexylamine) commonly referred to as (PACP), isophorone-diamine (noted 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.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.

[0077] A, Ca and Cb are as defined above.

[0078] When (Y) is at least one C4-C36 aliphatic dicarboxylic acid, preferably Cg-Cig, preferably Cg-Ci2, more preferably C10-C12, it is as defined for Cb. 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 mixtures thereof, in particular it is chosen from terephthalic acid (denoted T), isophthalic acid (denoted I) or mixtures thereof.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] 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.

[0083] 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. Advantageously, in this third variant, in which A / XY is chosen from the units 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. In a fourth variant, said at least one amorphous polyamide is a homopolyamide of formula XY, X being chosen from B or P and Y being sebacic acid or dodecanedioic acid.

[0084] Advantageously, in this fourth variant, XY is chosen from the BIO, B12, PIO, P12 patterns, and one of their mixtures.

[0085] The initial composition 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 but before use of said product. In one embodiment, said volatile constituents are chosen from constituents having a boiling point of less than 500°C, preferably 400°C, advantageously less than 350°C at atmospheric pressure, in particular chosen from plasticizers, monomers and oligomers having a degree of polymerization of less than or equal to 3, and organic stabilizers.

[0086] The term "atmospheric pressure" means 1013.25 hPa, or 1013.25 mb, or 760 mmHg, measured at sea level. Some constituents may be degraded before their boiling point under atmospheric pressure and must then be removed under reduced pressure.

[0087] 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.

[0088] The monomers correspond to the lactams and / or amino acids and / or diamines and carboxylic acids introduced to obtain the polyamide during its polycondensation.

[0089] Oligomers having a degree of polymerization less than or equal to 3, are derived from the monomers introduced above and correspond to dimers or trimers which may be cyclic or not. Said non-volatile constituents are chosen from impact modifiers, fillers, additives.

[0090] Additives are therefore non-volatile constituents.

[0091] The initial composition Cl comprises an initial (or virgin) polyamide and optionally the other constituents and is originally present in said element of said product.

[0092] In particular, said initial composition comprising one or more volatile or non-volatile constituent(s) before use, as defined above, said composition being called Cl, comprises by weight:

[0093] (a) from 30% to 99.9% of polyamide, in particular from 50 to 99.9%, in particular from 75% to 99.9% by weight,

[0094] (b) from 0.1 to 15% of plasticizer, in particular from 1 to 15.0% by weight,

[0095] (c) from 0 to 30% of impact modifiers, in particular from 1 to 15.0% by weight,

[0096] (d) from 0 to 5% of additives, in particular from 0.1 to 5.0% by weight,

[0097] (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,

[0098] (f) from 0 to 50% by weight of fibers and / or fillers, the sum of constituents (a) to (f) being equal to 100% and the initial proportion of said volatile constituent(s) (b) and (e) being from 0.1 to 21% by weight relative to the total weight of said composition Cl, in particular from 1 to 21%, especially from 1.1 to 20%.

[0099] In a first variant, said composition Cl comprises by weight:

[0100] (a) from 30% to 99% of polyamide, in particular from 50 to 99%, in particular from 75% to 99% by weight,

[0101] (b) from 1 to 15.0% by weight of plasticizer,

[0102] (c) from 0 to 30.0% by weight of impact modifiers,

[0103] (d) from 0 to 5% of additives, in particular from 0.1 to 5.0% by weight,

[0104] (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, the sum of the constituents (a) to (f) being equal to 100% and the initial proportion of said volatile constituent(s) (b) and (e) being from 1 to 21% by weight relative to the total weight of said initial composition Cl, in particular from 1.1 to 21%, in particular from 1.1 to 20%.

[0105] In a second variant, said composition Cl comprises by weight:

[0106] (a) from 30% to 98.9% of polyamide, in particular from 50 to 98%, in particular from 75% to 98% by weight,

[0107] (b) from 0.1 to 15% of plasticizer, in particular from 1 to 15.0% by weight,

[0108] (c) from 1 to 30.0% by weight of impact modifiers,

[0109] (d) from 0 to 5% of additives, in particular from 0.1 to 5.0% by weight,

[0110] (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,

[0111] (f) from 0 to 50% by weight of fibers and / or fillers, the sum of constituents (a) to (f) being equal to 100% and the initial proportion of said volatile constituent(s) (b) and (e) being from 0.1 to 21% by weight relative to the total weight of said initial composition Cl, in particular from 1.0 to 21%, especially from 1.1 to 20%.

[0112] In a third variant, said composition Cl comprises by weight:

[0113] (a) from 30% to 99.8% of polyamide, in particular from 50 to 98.9%, in particular from 75% to 98.9% by weight,

[0114] (b) from 0.1 to 15% of plasticizer, in particular from 1 to 15.0% by weight,

[0115] (c) from 0 to 30% of impact modifiers, in particular from 1 to 15.0% by weight,

[0116] (d) from 0.1 to 5.0% by weight of additives,

[0117] (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,

[0118] (f) from 0 to 50% by weight of fibers and / or fillers, the sum of constituents (a) to (f) being equal to 100% and the initial proportion of said volatile constituent(s) (b) and (e) being from 0.1 to 21% by weight relative to the total weight of said composition Cl, in particular from 1.0 to 21%, especially from 1.1 to 20%.

[0119] In a fourth variant, said composition Cl comprises by weight:

[0120] (a) from 30% to 99.8% of polyamide, in particular from 50 to 98.9%, in particular from 75% to 98.9% by weight,

[0121] (b) from 0.1 to 15% of plasticizer, in particular from 1 to 15.0% by weight,

[0122] (c) from 0 to 30% of impact modifiers, in particular from 1 to 15.0% by weight,

[0123] (d) from 0 to 5% of additives, in particular from 0.1 to 5.0% by weight of additives, (e) from 0.1 to 6%, 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 of less than or equal to 3, and organic stabilizers,

[0124] (f) from 0 to 50% by weight of fibers and / or fillers, the sum of constituents (a) to (f) being equal to 100% and the initial proportion of said volatile constituent(s) (b) and (e) being from 0.2 to 21% by weight relative to the total weight of said composition Cl, in particular from 1.1 to 21%, especially from 1.1 to 20%.

[0125] In one embodiment, said composition Cl is made up by weight of:

[0126] (a) from 30 to 99.9% of polyamide, in particular from 50 to 99%, in particular from 75% to 99% by weight,

[0127] (b) from 0.1 to 15% of plasticizer, in particular from 1 to 15.0% by weight,

[0128] (c) from 0 to 30% of impact modifiers, in particular from 1 to 15.0% by weight,

[0129] (d) from 0 to 5% of additives, in particular from 0.1 to 5.0% by weight,

[0130] (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,

[0131] (f) from 0 to 50% by weight of fibers and / or fillers, the sum of constituents (a) to (f) being equal to 100% and the initial proportion of said volatile constituent(s) (b) and (e) being from 0.1 to 21% by weight relative to the total weight of said composition Cl, in particular from 1.0 to 21%, especially from 1.1 to 20%.

[0132] In a first variant of this embodiment, said composition Cl consists of, by weight:

[0133] (a) from 30% to 99% of polyamide, in particular from 50 to 99%, in particular from 75% to 99% by weight,

[0134] (b) from 1 to 15.0% by weight of plasticizer,

[0135] (c) from 0 to 30.0% by weight of impact modifiers,

[0136] (d) from 0 to 5% of additives, in particular from 0.1 to 5.0% by weight,

[0137] (e) from 0 to 6% by weight, in particular from 0.1 to 6%, 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,

[0138] (f) from 0 to 50% by weight of fibers and / or fillers, the sum of constituents (a) to (f) being equal to 100% and the initial proportion of said volatile constituent(s) (b) and (e) being from 1 to 21% by weight relative to the total weight of said initial composition Cl, in particular from 1.1 to 21%, especially from 1.1 to 20%.

[0139] In a second variant of this embodiment, said composition Cl consists of, by weight:

[0140] (a) from 30% to 98.9% of polyamide, in particular from 50 to 98%, in particular from 75% to 98% by weight, (b) from 0.1 to 15% of plasticizer, in particular from 1 to 15.0% by weight,

[0141] (c) from 1 to 30.0% by weight of impact modifiers,

[0142] (d) from 0 to 5% of additives, in particular from 0.1 to 5.0% by weight,

[0143] (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,

[0144] (f) from 0 to 50% by weight of fibers and / or fillers, the sum of constituents (a) to (f) being equal to 100% and the initial proportion of said volatile constituent(s) (b) and (e) being from 0.1 to 21% by weight relative to the total weight of said initial composition Cl, in particular from 1.0 to 21%, especially from 1.1 to 20%.

[0145] In a third variant of this embodiment, said composition Cl consists of, by weight:

[0146] (a) from 30% to 99.8% of polyamide, in particular from 50 to 98.9%, in particular from 75% to 98.9% by weight,

[0147] (b) from 0.1 to 15% of plasticizer, in particular from 1 to 15.0% by weight,

[0148] (c) from 0 to 30% of impact modifiers, in particular from 1 to 15.0% by weight,

[0149] (d) from 0.1 to 5.0% by weight of additives,

[0150] (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,

[0151] (f) from 0 to 50% by weight of fibers and / or fillers, the sum of constituents (a) to (f) being equal to 100% and the initial proportion of said volatile constituent(s) (b) and (e) being from 0.1 to 21% by weight relative to the total weight of said composition Cl, in particular from 1.0 to 21%, especially from 1.1 to 20%.

[0152] In a fourth variant of this embodiment, said composition Cl consists of, by weight:

[0153] (a) from 30% to 99.8% of polyamide, in particular from 50 to 98.9%, in particular from 75% to 98.9% by weight,

[0154] (b) from 0.1 to 15% of plasticizer, in particular from 1 to 15.0% by weight,

[0155] (c) from 0 to 30% of impact modifiers, in particular from 1 to 15.0% by weight,

[0156] (d) from 0 to 5% of additives, in particular from 0.1 to 5.0% by weight of additives,

[0157] (e) from 0.1 to 6%, 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,

[0158] (f) from 0 to 50% by weight of fibers and / or fillers, the sum of constituents (a) to (f) being equal to 100% and the initial proportion of said volatile constituent(s) (b) and (e) being from 0.2 to 21% by weight relative to the total weight of said composition Cl, in particular from 1.1 to 21%, especially from 1.1 to 20%.

[0159] This initial composition Cl which includes 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 during or after the processing of said polyamide but before use of said product. It will therefore constitute “pre-consumer” waste.

[0160] The plasticizer is optional and ranges from 0 to 15.0%, in particular from 0.1 to 15.0% by weight.

[0161] For example, the plasticizers are selected 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), hydroxybenzoic acid esters such as ethyl-2 hexyl para-hydroxybenzoate (EHPB) and decyl-2 hexyl para-hydroxybenzoate (HDPB), tetrahydrofurfuryl alcohol esters or ethers such as oligoethyleneoxy-tetrahydrofurfuryl alcohol, and citric acid or hydroxymalonic acid esters, such as oligoethyleneoxymalonate. A preferred plasticizer is n-butyl benzene sulfonamide (BBSA).

[0162] The impact modifier is optional and ranges from 0 to 30%, in particular from 1 to 15% by weight.

[0163] The impact modifier is advantageously made up of a polymer having a flexural modulus of less than 100 MPa measured according to standard ISO 178 and a Tg of less than 0°C (measured according to standard 11357-2 at the inflection point of the DSC thermogram), in particular a polyolefin.

[0164] 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.

[0165] The additive is optional and ranges from 0 to 5.0%, in particular from 0.1 to 5.0% by weight. It is non-volatile.

[0166] The additive is selected from colorants, inorganic stabilizers, catalysts, surfactants, nucleating agents, pigments, brighteners, antioxidants, lubricants, flame retardants, natural waxes, bases and mixtures thereof.

[0167] 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.

[0168] The term "catalyst" refers to a polycondensation catalyst such as a mineral or organic acid.

[0169] Advantageously, the catalyst is chosen from phosphoric acid (H3PO4), phosphorous acid (H3PO3), hypophosphorous acid (H3PO2), or a mixture thereof. Advantageously, said composition Cl before use of said product has a catalyst content by weight of from 0 to 9000 ppm, 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 composition Cl.

[0170] Advantageously, when said product is a single-layer or multi-layer structure, said polyamide of said structure before its use 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 polyamide.

[0171] Fibers and / or fillers are optional and their proportion is from 0 to 50% by weight.

[0172] For example, the fibers may be chosen from aramid fibers, glass fibers, carbon fibers, advantageously glass fibers or carbon fibers.

[0173] For 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, preferably talc.

[0174] In one embodiment, said constituents are volatile compounds at atmospheric pressure, i.e. the boiling point of said constituents is less than 500°C, preferably 400°C, advantageously less than 350°C.

[0175] 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 250°C, advantageously less than 200°C under 5 hPa of pressure.

[0176] In one embodiment, the polyamide to be recycled of composition C1 is devoid of catalyst. In one embodiment, when said product is a monolayer or multilayer structure, said volatile compounds are chosen from a plasticizer, a monomer and an oligomer having a degree of polymerization less than or equal to 3.

[0177] In one embodiment, said volatile compound is a plasticizer.

[0178] Regarding the process

[0179] Said method comprises steps a) to e) as defined above.

[0180] 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 volatile constituents present in said product and in particular in said polyamide.

[0181] Another purpose of the said process is to be able to recycle certain constituents originally present in the said polyamide.

[0182] The initial proportion of said constituent(s) in said product is from 0 to 20% by weight relative to the total weight of said product, in particular from 0.1 to 20%. In the case where said product is made up of elements other than said polyamide, said proportion of said constituent(s) is predominantly if not entirely present in said polyamide.

[0183] The term “elements” means any material present in the product and other than said polyamide. Examples include metals and polymer compositions comprising less than 30% polymer, in particular polyamide other than said polyamide.

[0184] 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.

[0185] 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.

[0186] 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 polyamide layer and at least one other layer made 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 for example in an offshore pipe. The other elements therefore correspond to this other layer or layers. The separation of said polyamide layer from the other layer or layers 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, separation can be done by peeling.

[0187] 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.

[0188] When the said structure corresponds to a structure obtained by rotational molding or extrusion-blow molding, for example a tank or a hollow body, the treatment is similar to that used for structures obtained by extrusion.

[0189] 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.

[0190] Depending on the state of said untreated product in step a) or said polyamide separated after treatment in step a), 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. Said shaping may then be mechanical or cryogenic grinding to obtain particles having a 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.

[0191] Preferably, the products are optionally shredded and then ground to obtain particles with a D50 of less than 1cm.

[0192] 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 and transporting a polymer continuously and having a degassing surface, in particular under reduced pressure.

[0193] The degassing surface or zone may also be referred to as the evaporation surface or zone.

[0194] The degassing surface or zone makes it possible to reduce or eliminate constituents which correspond to volatile compounds under atmospheric pressure.

[0195] 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.

[0196] Above 85,000, the molten polyamide is too viscous for the said constituents to be removed or reduced by degassing.

[0197] 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.

[0198] In one embodiment, said system is an extruder, in particular a multi-screw extruder, in particular an extruder with a multi-rotational system.

[0199] Advantageously, said multi-screw extruder has a number of screws greater than 2, in particular greater than 5.

[0200] Step d) consists of carrying out an extrusion with degassing, in particular under reduced pressure, continuously in the molten state of said optionally shaped product or of said separated polyamide shaped and introduced in step c) at a temperature higher than the Tm 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 one or more constituent(s).

[0201] 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.

[0202] This step therefore makes it possible to reduce or eliminate the constituents which correspond to volatile compounds under atmospheric pressure, in particular under reduced pressure. The vacuum applied for the reduced pressure is then in particular between 100 and 0.1 hPa, preferably between 60 and 0.1 hPa, in particular 40 hPa to 0.1 hPa, in particular from 25 hPa to 0.5 hPa, in particular from 3 hPa to 1 hPa.

[0203] In one embodiment, said temperature is from 150°C to 350°C, in particular from 200°C to 300°C.

[0204] However, 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).

[0205] 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 between 10,000 and 85,000 g / mol, in particular

[0206] 10,000 to 60,000 g / mol, especially 10,000 to 50,000 g / mol.

[0207] Likewise, if the polyamide to be recycled comprises a catalyst, the proportion of said catalyst must be 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.

[0208] In one embodiment, said extrusion with degassing of step d) is carried out under reduced pressure for a time greater than or equal to 1 min, in particular from 1 to 5 min.

[0209] Below 1 minute, the time is not sufficient to eliminate or sufficiently reduce the proportion of constituents in said product or said polyamide.

[0210] Beyond 5 min, the proportion of constituents which is eliminated or reduced in said product or said polyamide no longer varies significantly.

[0211] In another embodiment, said degassing surface is > 5000 mm 2 / kg / h, from 5000 to 100,000 mm 2 / kg / h, preferably 6000 to 50,000 mm 2 / kg / h, advantageously from 7,000 to 20,000 mm 2 / kg / h. This surface, in the case of degassing along one or more screws, corresponds to the maximum degassing surface regardless of the filling rate in the extruder.

[0212] In the case of a multi-screw extruder, it therefore corresponds to the perimeter of the screw (mm) x length of the degassing zone (mm) x number of screws divided by the flow rate (kg / h). The length of the degassing zone is defined as the length between 2 zones where the filling rate is equal to 1. The filling rate is defined as the ratio between the volume of molten polymer and the free volume. A ratio equal to 1 therefore corresponds to a so-called full zone. These full zones make it possible to obtain a dynamic plug which allows degassing to be applied in a well-defined zone.

[0213] The length is either given by the TDS of the device from the manufacturer or by the design of the screw profile, i.e. the length between two solid areas.

[0214] It is also possible to check that the area is full by simultaneously stopping the material feed to the device and the rotation speed of the screws, then after the screws have come out, to check that the polyamide is indeed over the entire volume of the screw cylinder. In the case of a technology where the polymer is spread other than by varying the number of screws, this is the surface of the molten polymer subjected to degassing.

[0215] Advantageously, the degassing flow rate of step d) is > 100 kg / h, in particular > 150 kg / h.

[0216] More preferably, the reduced pressure is from 0.1 hPa to 40 hPa, in particular from 0.5 hPa to 25 hPa.

[0217] 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 glass transition 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 so that they can be eliminated in said process.

[0218] It is then possible to recover said constituent 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. 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) present in said product or polyamide.

[0219] In one embodiment, said constituent is a plasticizer, in particular N-butylbenzenesulfonamide (BBSA).

[0220] In one embodiment, said constituents are removed to at least 60% by weight relative to the total weight of the constituents present in said product or said polyamide, in particular at least 70%, in particular at least 80%, in particular at least 85%, more particularly at least 90%, even more particularly at least 95%.

[0221] The majority of volatile constituents are therefore eliminated after this step d).

[0222] Step e) 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 <3%, in particular <2%, in particular <1%. In one embodiment, the melted polyamide of step e) has an Mn greater than or equal to 500 g / mol, in particular from 500 to 85,000 g / mol, in particular from 500 to 60,000 g / mol, more particularly from 500 to 50,000 g / mol.

[0223] 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 ​​5000 mm 2 / kg / h at 100,000 mm 2 / kg / h, preferably 10,000 to 50,000 mm 2 / kg / h and at a temperature of 180 to 350°C, preferably 250 to 300°C.

[0224] 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) or d).

[0225] The bases can be organic or inorganic, advantageously chosen from NaOH, KOH and carbonates.

[0226] When in particular said polyamide to be recycled from step c) or d) 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.

[0227] Conversely, said polyamide to be recycled from step c) or d) 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.

[0228] The molten polyamide from step e) 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.

[0229] The expression “molecule comprising one or more carboxylic acid functions, one or more primary amine functions, one or more alcohol functions and one or more ester functions” designates any molecule having at least one carboxylic acid function or one amine function or one alcohol function or one ester function.

[0230] In another embodiment, said component is chosen from molecules comprising one or more carboxylic acid and primary amine functions.

[0231] In one embodiment, a single molecule is added whose functionality is from 1 to 3.

[0232] The term functionality only concerns carboxylic acid and primary amine functions.

[0233] In another embodiment, several molecules are added whose average functionality is between 1.8 and 2.2.

[0234] In yet another embodiment, several molecules are added whose average functionality is from 0.8 to 1.2.

[0235] Advantageously, said molecule is a chain limiter.

[0236] 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.

[0237] Examples of linear aliphatic C2-C18 monocarboxylic acids are 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.

[0238] Advantageously, said linear aliphatic monocarboxylic acid is C2-C12, in particular C2-C6, in particular acetic acid.

[0239] 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.

[0240] Advantageously, said linear aliphatic monoamine is C4-C12, in particular C4-C6.

[0241] The linear aliphatic C3-C36 dicarboxylic acid (or dicarboxylic acid) may 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.

[0242] 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 EP 0471 566.

[0243] Advantageously, said dicarboxylic acid is C3-C18, in particular C3-C12, in particular C3-C6.

[0244] 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.

[0245] Advantageously, said linear aliphatic diamine is C4-C12, in particular C4-C6.

[0246] The linear aliphatic diamines just mentioned can all be bio-resourced within the meaning of the ASTM D6866 standard.

[0247] Said C6 to C18 aminocarboxylic acid.

[0248] It can thus be chosen from 6-aminohexanoic acid denoted (6), 7-aminohexanoic acid (denoted 7), 8-aminohexanoic acid (denoted 8), 9-aminononanoic acid (denoted 9), 10-aminodecanoic acid (denoted 10), 11-aminoundecanoic acid (denoted 11) and 12-aminododecanoic acid (denoted 12). Advantageously, said aminocarboxylic acid comprises from 9 to 12 carbon atoms, advantageously the aminocarboxylic acid is 11-aminoundecanoic acid. 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.

[0249] In another embodiment, the chain limiter is adipic acid.

[0250] 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).

[0251] 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%.

[0252] In a second variant of the invention, in the process described above, step c) or d) 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.

[0253] In one embodiment, in the process defined above, the polyamide of the final composition obtained in step e) 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.

[0254] 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.

[0255] Acidity and basicity are measured by potentiometry.

[0256] Acidity is measured using the following method. A sample of polyamide is dissolved in benzyl alcohol. This sample is then assayed potentiometrically using a 0.02N tetrabutylammonium hydroxide solution.

[0257] Basicity is measured using the following method. A sample of polyamide is dissolved in metacresol. This sample is then assayed potentiometrically using a 0.02N perchloric acid solution.

[0258] According to another aspect, the present invention relates to a product obtainable by the process as defined above.

[0259] Regarding recycled polyamide and the composition comprising it

[0260] The recycled polyamide therefore corresponds to the product obtained or likely to be obtained by the process of the invention.

[0261] 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 between 1.3 dl / g and 1.8 dl / g.

[0262] Said recycled polyamide has an MFI of 0.1 to 50 g / 10 min.

[0263] MFI, short for Melt Flow Index, is the melt flow index. It is measured according to ISO 1133 at 235°C under 5 kg.

[0264] The proportion of volatile constituents in said composition after recycling is at least 10 times lower than that present in the composition comprising the polyamide to be recycled.

[0265] According to another aspect, the present invention relates to the use of the granules obtained in step e. of the process defined above, for the preparation of articles obtained by extrusion.

[0266] 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.

[0267] Additives are as defined above.

[0268] In one embodiment, the article is a single-layer or multi-layer structure for transporting, distributing or storing fluids.

[0269] In a variant of this embodiment, said structure is chosen from a fluid transport pipe for an automobile.

[0270] In another variant of this embodiment, said structure is an oil or gas field exploitation pipe, underwater or on land.

[0271] According to another aspect, the present invention relates to the use of the granules obtained in step e. of the process defined above, for the preparation of articles obtained by injection.

[0272] 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, knees,of the 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. According to yet another aspect, the present invention relates to the use of the constituents, in particular the constituents obtained by the degassing carried out in step d) of the process defined above for the preparation of compounds, in particular polyamides.,

[0273] In one embodiment, said constituents are compounds volatile at atmospheric pressure chosen from a plasticizer, a monomer and an oligomer having a degree of polymerization less than or equal to 3 and organic stabilizers.

[0274] Advantageously, said constituent is a plasticizer.

[0275] The present invention therefore makes it possible to separate the constituents, in particular the plasticizer, from the polyamide to be recycled and consequently to also recycle both said polyamides for new compounds, in particular polyamides, and the plasticizer for another use.

[0276] Regarding composition C2 obtained after recycling composition Cl

[0277] The Cl composition of the element after recycling is likely to have lost all or part of the volatile constituent(s) present initially to lead to a C2 composition.

[0278] In particular, composition C2 comprises by weight:

[0279] (a) from 30% to 99.999% of polyamide, in particular from 50 to 99.999%, in particular from 75% to 99.999% by weight,

[0280] (b) from 0 to 0.1% by weight, in particular from 0.001 to 0.1% by weight of plasticizer,

[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 1% by weight, in particular from 0.001 to 1% by weight, in particular 0.001 to 0.1% by weight of a compound chosen from monomers and oligomers having a degree of polymerization less than or equal to 3, and organic stabilizers,

[0284] (f) from 0 to 50% by weight of fibers and / or fillers, the sum of constituents (a) to (f) being equal to 100% and the final proportion of said volatile constituent(s) (b) and (e) being from 0 to 1.1% by weight relative to the total weight of said composition C2, in particular from 0.001 to 1.1%, in particular from 0.001 to 1%, in particular 0.002 to 0.1%.

[0285] In a first variant, said composition C2 comprises by weight:

[0286] (a) from 30% to 99.999% of polyamide, in particular from 50 to 99.998%, in particular from 75% to 99.899% by weight,

[0287] (b) from 0.001 to 0.1% by weight of plasticizer,

[0288] (c) from 0 to 30% by weight, in particular from 1 to 15.0% by weight of impact modifiers,

[0289] (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, in particular from 0.1 to 1% of a compound chosen from monomers and oligomers having a degree of polymerization less than or equal to 3, and organic stabilizers,

[0290] (f) from 0 to 50% by weight of fibers and / or fillers, the sum of constituents (a) to (f) being equal to 100% and the final proportion of said volatile constituent(s) (b) and (e) being from 0.001 to 1.1% by weight relative to the total weight of said composition C2, in particular from 0.002 to 1.1%, in particular from 0.101 to 1.1%, in particular 0.101 to 0.1%.

[0291] In a second variant, said composition C2 comprises by weight:

[0292] (a) from 30% to 99% of polyamide, in particular from 50 to 98.999%, in particular from 75% to 98.998% by weight,

[0293] (b) from 0 to 0.1% by weight, in particular from 0.001 to 0.1% by weight of plasticizer,

[0294] (c) from 1 to 15.0% by weight of impact modifiers,

[0295] (d) from 0 to 5% of additives, in particular from 0.1 to 5.0% by weight,

[0296] (e) from 0 to 1% by weight, in particular from 0.001 to 1% by weight, in particular from 0.1 to 1% of a compound chosen from monomers and oligomers having a degree of polymerization less than or equal to 3, and organic stabilizers,

[0297] (f) from 0 to 50% by weight of fibers and / or fillers, the sum of constituents (a) to (f) being equal to 100% and the final proportion of said volatile constituent(s) (b) and (e) being from 0 to 1.1% by weight relative to the total weight of said composition C2, in particular from 0.001 to 1.1%, in particular from 0.001 to 1%, in particular 0.002 to 0.1%.

[0298] In a third variant, said composition C2 comprises by weight:

[0299] (a) from 30% to 99.9% of polyamide, in particular from 50 to 99.899%, in particular from 75% to 99.898% by weight,

[0300] (b) from 0 to 0.1% by weight, in particular from 0.001 to 0.1% by weight of plasticizer,

[0301] (c) from 0 to 20% of impact modifiers, in particular from 1 to 15.0% by weight,

[0302] (d) from 0.1 to 5.0% by weight of additives,

[0303] (e) from 0 to 1% by weight, in particular from 0.001 to 1% by weight, in particular from 0.1 to 1% of a compound chosen from monomers and oligomers having a degree of polymerization less than or equal to 3, and organic stabilizers,

[0304] (f) from 0 to 50% by weight of fibers and / or fillers, the sum of constituents (a) to (f) being equal to 100% and the final proportion of said volatile constituent(s) (b) and (e) being from 0 to 1.1% by weight relative to the total weight of said composition C2, in particular from 0.001 to 1.1%, in particular 0.001 to 1%, in particular from 0.002 to 0.1%.

[0305] In a fourth variant, said composition C2 comprises by weight:

[0306] (a) from 30% to 99.999% of polyamide, in particular from 50 to 99.998%, in particular from 75% to 99.899% by weight,

[0307] (b) from 0 to 0.1% by weight, in particular from 0.001 to 0.1% by weight of plasticizer,

[0308] (c) from 0 to 20% of impact modifiers, in particular from 1 to 15.0% by weight,

[0309] (d) from 0 to 5% of additives, in particular from 0.1 to 5.0% by weight of additives,

[0310] (e) from 0.001 to 1% by weight, in particular from 0.1 to 1% of a compound chosen from monomers and oligomers having a degree of polymerization less than or equal to 3, and organic stabilizers,

[0311] (f) from 0 to 50% by weight of fibers and / or fillers, the sum of constituents (a) to (f) being equal to 100% and the final proportion of said volatile constituent(s) (b) and (e) being from 0.001 to 1.1% by weight relative to the total weight of said composition C2, in particular from 0.002 to 1.1%, in particular from 0.101 to 1%, in particular 0.101 to 0.1%.

[0312] In a fifth variant, said composition C2 comprises by weight:

[0313] (a) from 30% to 99.8% of polyamide, in particular from 50 to 98.8%, in particular from 75% to 98.8% by weight,

[0314] (b) from 0.001 to 0.1% by weight of plasticizer,

[0315] (c) from 0 to 20% of impact modifiers, in particular from 1 to 15.0% by weight,

[0316] (d) from 0 to 5% of additives, in particular from 0.1 to 5.0% by weight of additives,

[0317] (e) from 0.001 to 1% by weight, in particular from 0.1 to 1% of a compound chosen from monomers and oligomers having a degree of polymerization less than or equal to 3, and organic stabilizers,

[0318] (f) from 0 to 50% by weight of fibers and / or fillers, the sum of constituents (a) to (f) being equal to 100% and the final proportion of said volatile constituent(s) (b) and (e) being from 0.002 to 1.1% by weight relative to the total weight of said composition C2, in particular from 0.101 to 1.1%, in particular 0.101 to 1%, in particular 0.101 to 0.1%.

[0319] In one embodiment, said composition C2 consists of, by weight:

[0320] (a) from 30% to 99.999% of polyamide, in particular from 50 to 99.999%, in particular from 75% to 99.999% by weight,

[0321] (b) from 0 to 0.1% by weight, in particular from 0.001 to 0.1% by weight of plasticizer,

[0322] (c) from 0 to 30% of impact modifiers, in particular from 1 to 15.0% by weight,

[0323] (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, in particular 0.001 to 0.1% by weight of a compound chosen from monomers and oligomers having a degree of polymerization of less than or equal to 3, and organic stabilizers,

[0324] (f) from 0 to 50% by weight of fibers and / or fillers, the sum of constituents (a) to (f) being equal to 100% and the final proportion of said volatile constituent(s) (b) and (e) being from 0 to 1.1% by weight relative to the total weight of said composition C2, in particular from 0.001 to 1.1%, in particular from 0.001 to 1%, in particular 0.002 to 0.1%.

[0325] In a first variant, said composition C2 consists of, by weight:

[0326] (a) from 30% to 99.999% of polyamide, in particular from 50 to 99.998%, in particular from 75% to 99.899% by weight,

[0327] (b) from 0.001 to 0.1% by weight of plasticizer,

[0328] (c) from 0 to 30% by weight, in particular from 1 to 15.0% by weight of impact modifiers,

[0329] (d) from 0 to 5% of additives, in particular from 0.1 to 5.0% by weight,

[0330] (e) from 0 to 1% by weight, in particular from 0.001 to 1% by weight, in particular from 0.1 to 1% of a compound chosen from monomers and oligomers having a degree of polymerization less than or equal to

[0331] 3, and organic stabilizers,

[0332] (f) from 0 to 50% by weight of fibers and / or fillers, the sum of constituents (a) to (f) being equal to 100% and the final proportion of said volatile constituent(s) (b) and (e) being from 0.001 to 1.1% by weight relative to the total weight of said composition C2, in particular from 0.002 to 1.1%, in particular from 0.101 to 1%, in particular 0.101 to 0.1%.

[0333] In a second variant, said composition C2 consists of, by weight:

[0334] (a) from 30% to 99% of polyamide, in particular from 50 to 98.999%, in particular from 75% to 98.998% by weight,

[0335] (b) from 0 to 0.1% by weight, in particular from 0.001 to 0.1% by weight of plasticizer,

[0336] (c) from 1 to 15.0% by weight of impact modifiers,

[0337] (d) from 0 to 5% of additives, in particular from 0.1 to 5.0% by weight,

[0338] (e) from 0 to 1% by weight, in particular from 0.001 to 1% by weight, in particular from 0.1 to 1% of a compound chosen from monomers and oligomers having a degree of polymerization less than or equal to 3, and organic stabilizers,

[0339] (f) from 0 to 50% by weight of fibers and / or fillers, the sum of constituents (a) to (f) being equal to 100% and the final proportion of said volatile constituent(s) (b) and (e) being from 0 to 1.1% by weight relative to the total weight of said composition C2, in particular from 0.001 to 1.1%, in particular from 0.001 to 1%, in particular 0.002 to 0.1%.

[0340] In a third variant, said composition C2 consists of, by weight:

[0341] (a) from 30% to 99.9% of polyamide, in particular from 50 to 99.899%, in particular from 75% to 99.898% by weight,

[0342] (b) from 0 to 0.1% by weight, in particular from 0.001 to 0.1% by weight of plasticizer,

[0343] (c) from 0 to 20% of impact modifiers, in particular from 1 to 15.0% by weight,

[0344] (d) from 0.1 to 5.0% by weight of additives,

[0345] (e) from 0 to 1% by weight, in particular from 0.001 to 1% by weight, in particular from 0.1 to 1% of a compound chosen from monomers and oligomers having a degree of polymerization less than or equal to 3, and organic stabilizers,

[0346] (f) from 0 to 50% by weight of fibers and / or fillers, the sum of constituents (a) to (f) being equal to 100% and the final proportion of said volatile constituent(s) (b) and (e) being from 0 to 1.1% by weight relative to the total weight of said composition C2, in particular from 0.001 to 1.1%, in particular 0.001 to 1%, in particular from 0.002 to 0.1%.

[0347] In a fourth variant, said composition C2 consists of, by weight:

[0348] (a) from 30% to 99.999% of polyamide, in particular from 50 to 99.998%, in particular from 75% to 99.899% by weight,

[0349] (b) from 0 to 0.1% by weight, in particular from 0.001 to 0.1% by weight of plasticizer,

[0350] (c) from 0 to 20% of impact modifiers, in particular from 1 to 15.0% by weight,

[0351] (d) from 0 to 5% of additives, in particular from 0.1 to 5.0% by weight of additives,

[0352] (e) from 0.001 to 1% by weight, in particular from 0.1 to 1% of a compound chosen from monomers and oligomers having a degree of polymerization less than or equal to 3, and organic stabilizers,

[0353] (f) from 0 to 50% by weight of fibers and / or fillers, the sum of constituents (a) to (f) being equal to 100% and the final proportion of said volatile constituent(s) (b) and (e) being from 0.001 to 1.1% by weight relative to the total weight of said composition C2, in particular from 0.002 to 1.1%, in particular from 0.101 to 1%, in particular 0.101 to 0.1%.

[0354] In a fifth variant, said composition C2 consists of, by weight:

[0355] (a) from 30% to 99.8% of polyamide, in particular from 50 to 98.8%, in particular from 75% to 98.8% by weight,

[0356] (b) from 0.001 to 0.1% by weight of plasticizer,

[0357] (c) from 0 to 20% of impact modifiers, in particular from 1 to 15.0% by weight,

[0358] (d) from 0 to 5% of additives, in particular from 0.1 to 5.0% by weight of additives, (e) from 0.001 to 1% by weight, in particular from 0.1 to 1% of a compound chosen from monomers and oligomers having a degree of polymerization of less than or equal to 3, and organic stabilizers,

[0359] (f) from 0 to 50% by weight of fibers and / or fillers, the sum of constituents (a) to (f) being equal to 100% and the final proportion of said volatile constituent(s) (b) and (e) being from 0.002 to 1.1% by weight relative to the total weight of said composition C2, in particular from 0.101 to 1.1%, in particular 0.101 to 1.0%, in particular 0.101 to 0.1%.

[0360] The definition of components (a) to (f) is the same as for composition Cl.

[0361] In one embodiment, the proportion of plasticizer removed relative to its initial proportion is greater than the proportion of monomers and oligomers and / or organic stabilizers removed relative to their initial proportion.

[0362] This proportion can be determined by infrared TGA analysis.

[0363] EXAMPLES

[0364] The present invention will now be illustrated by examples without being limited thereto.

[0365] Example 1: Recycling of polyamide 12 from offshore pipes before use in a multi-rotation system extruder without chain limiter

[0366] The polyamide product to be recycled is a sheath constituting one of the layers of the offshore pipe before use. This sheath was prepared using 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, 2% monomer and oligomers with a degree of polymerization less than or equal to 3 and 1.2% non-volatile additives.

[0367] The other layers of the offshore pipe are composed of metal sheaths. After recovering the offshore pipe before use, 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).

[0368] Step c) then consists of introducing said polyamide 12 recovered in step b) into a multi-rotational system extruder MRSjump 70 from the company Gneuss.

[0369] 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 5 screws with a diameter of 35 mm and a length of 50 times the diameter, i.e. 1750 mm. The degassing surface per unit of flow rate is therefore in this example 13745 mm 2 / kg / h.

[0370] Step e) consists of the recovery of polyamide 12 in solid form by granulation of the molten polyamide using the underwater granulation process known to those skilled in the art. Example 2 (comparative): recycling of polyamide 12 from offshore pipes in a co-rotating twin-screw extruder without chain limiter

[0371] The polyamide product to be recycled is a sheath constituting one of the layers of the offshore pipe before use. This sheath was prepared using 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, 2% monomer and oligomers with a degree of polymerization less than or equal to 3 and 1.2% non-volatile additives.

[0372] The other layers of the offshore pipe are composed of metal sheaths. After recovering the offshore pipe before use, 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).

[0373] 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.

[0374] 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 two screws with a diameter of 40 mm and 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 mm 2 / kg / h.

[0375] Step e) consists of recovering the polyamide 12 in solid form by granulating the molten polyamide using the underwater granulation process known to those skilled in the art.

[0376] Example 3: Recycling of polyamide 11 from offshore pipes before use in a multi-rotation system extruder with chain limiter (adipic acid)

[0377] 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 containing 12% BBSA plasticizer, 2% monomer and oligomers having a degree of polymerization less than or equal to 3, 800 ppm catalyst and 1.2% non-volatile additives.

[0378] The other layers of the offshore pipe are composed of metal sheaths. After recovering the offshore pipe before use, 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).

[0379] Step c) then consists of introducing said polyamide 11 recovered in step b) with the addition of 1% adipic acid into a multi-rotational system extruder MRSjump 70 from the company Gneuss. Step d) consists of extrusion at 70 kg / h and for a temperature of 280°C with degassing under reduced pressure of 10 mbar. 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 5 screws with a diameter of 35 mm for a length of 50 times the diameter, i.e. 1750 mm. The degassing surface per unit of flow rate is therefore in this example 13745 mm 2 / kg / h.

[0380] Step e) consists of recovering the polyamide 11 in solid form by granulating the molten polyamide using the underwater granulation process known to those skilled in the art.

[0381] Example 4: Recycling of impact-modified polyamide 11 from offshore pipes before use in a multi-rotational system extruder with chain limiter (adipic acid)

[0382] 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 containing 12% BBSA plasticizer, 10% impact modifier, 2% monomer and oligomers having a degree of polymerization less than or equal to 3, 800 ppm catalyst and 1.2% non-volatile additives.

[0383] The other layers of the offshore pipe are composed of metal sheaths. After recovering the offshore pipe before use, 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).

[0384] Step c) then consists of introducing said polyamide 11 recovered in step b) with the addition of 1% adipic acid into a multi-rotational system extruder MRSjump 70 from the company Gneuss. Step d) consists of extrusion at 70 kg / h and for a temperature of 280°C with degassing under reduced pressure of 10 mbar. 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 5 screws with a diameter of 35 mm for a length of 50 times the diameter, i.e. 1750 mm. The degassing surface per unit of flow rate is therefore in this example 13745 mm 2 / kg / h.

[0385] Step e) consists of recovering the polyamide 11 in solid form by granulating the molten polyamide using the underwater granulation process known to those skilled in the art.

[0386] Example 5: Recycling of polyamide 12 loaded from offshore pipes before use in a multi-rotation system extruder without chain limiter

[0387] The recycling process is as defined for Example 1.

[0388] The charge corresponds to 20% by weight relative to the total weight of the composition of the polyamide sheath. Example 6: recycling of polyamide 11 from purge blocks in an extruder with a multi-rotational system with chain limiter (adipic acid)

[0389] The polyamide product to be recycled is in the form of polyamide blocks produced during purges of a reactor or an extruder at the start or end of production. The composition of these polyamide blocks is a polyamide 11 containing 12% BBSA plasticizer, 2% monomer and oligomers with a degree of polymerization less than or equal to 3, 800 ppm of catalyst and 1.2% of non-volatile additives.

[0390] These blocks are crushed without any prior step to obtain a ground material of approximately 6 mm in size (step b).

[0391] Step c) then consists of introducing said polyamide 11 recovered in step b) with the addition of 1% adipic acid into a multi-rotational system extruder MRSjump 70 from the company Gneuss. Step d) consists of extrusion at 70 kg / h and for a temperature of 280°C with degassing under reduced pressure of 10 mbar. 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 5 screws with a diameter of 35 mm for a length of 50 times the diameter, i.e. 1750 mm. The degassing surface per unit of flow rate is therefore in this example 13745 mm 2 / kg / h.

[0392] Step e) consists of recovering the polyamide 11 in solid form by granulating the molten polyamide using the underwater granulation process known to those skilled in the art.

[0393] Example 7: recycling of polyamide 11 from injected parts before use in a multi-rotational system extruder with chain limiter (adipic acid)

[0394] The polyamide product to be recycled is in the form of injected parts. These injected parts were prepared using the injection molding process known to those skilled in the art. The composition of these injected parts is a polyamide 11 containing 12% BBSA plasticizer, 2% monomer and oligomers with a degree of polymerization less than or equal to 3, 800 ppm catalyst and 1.2% non-volatile additives.

[0395] These injected parts are ground without any prior step to obtain a ground material of approximately 6 mm in size (step b).

[0396] Step c) then consists of introducing said polyamide 11 recovered in step b) with the addition of 1% adipic acid into a multi-rotational system extruder MRSjump 70 from the company Gneuss. Step d) consists of extrusion at 70 kg / h and for a temperature of 280°C with degassing under reduced pressure of 10 mbar. 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 5 screws with a diameter of 35 mm for a length of 50 times the diameter, i.e. 1750 mm. The degassing surface per unit of flow rate is therefore in this example 13745 mm 2 / kg / h. Step e) consists of the recovery of polyamide 11 in solid form by granulation of the molten polyamide using the underwater granulation process known to those skilled in the art.

[0397] Example 8: Recycling of polyamide 11 from a hydrogen tank in a multi-rotation system extruder with chain limiter (adipic acid)

[0398] The polyamide product to be recycled is in the form of an inner layer of a hydrogen tank. This inner layer was prepared using the rotational molding process known to those skilled in the art. The composition of these injected parts is a polyamide 11 containing 4% BBSA plasticizer, 2% monomer and oligomers having a degree of polymerization less than or equal to 3, 800 ppm catalyst and 1.2% non-volatile additives.

[0399] This inner layer of polyamide 11 is recovered after cutting the tank in two lengthwise (step a). This inner layer is then ground to obtain a ground material of approximately 6 mm in size (step b).

[0400] Step c) then consists of introducing said polyamide 11 recovered in step b) with the addition of 1% adipic acid into a multi-rotational system extruder MRSjump 70 from the company Gneuss. Step d) consists of extrusion at 70 kg / h and for a temperature of 280°C with degassing under reduced pressure of 10 mbar. 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 5 screws with a diameter of 35 mm for a length of 50 times the diameter, i.e. 1750 mm. The degassing surface per unit of flow rate is therefore in this example 13745 mm 2 / kg / h.

[0401] Step e) consists of recovering the polyamide 11 in solid form by granulating the molten polyamide using the underwater granulation process known to those skilled in the art.

[0402] Comparative example 9: recycling of polyamide 11 from a hydrogen tank in a “conventional” extruder with chain limiter (adipic acid)

[0403] The protocol is as described in example 2 except that 1% adipic acid is added in step c).

[0404] The initial compositions Cl for preparing the offshore pipes, purge blocks, injected parts and hydrogen tank of the above examples are as follows (by weight):

[0405] [Table 1]

[0406]

[0407] PA stands for polyamide.

[0408] Cat. means catalyst and is phosphoric acid.

[0409] Plast. means plasticizer and is BBSA (N-Butyl Benzene Sulfonamide), marketed by Partners in Chemical.

[0410] IM stands for impact modifier and is EXXELOR® VA 1801, marketed by Vanderbilt Chemicals, LLC. The filler is Ensaco® Carbon Black and is marketed by Imerys.

[0411] After treatment by a multi-rotational system extruder or co-rotating twin-screw extruder under different conditions in the presence or absence of adipic acid, the rate of volatiles remaining in the final C2 compositions obtained is determined according to an ATG protocol according to standard ISO 11358:2022 and is indicated in the following table 2 (by weight): [Table 2] Table 2 shows that the proportion of volatiles remaining in the different compositions C2 resulting from compositions C1 according to examples 1 and 3 to 8 originating from different products after recycling according to the invention is less than 3% 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 examples 2 and 9 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.

[0412] Similarly, the percentage reduction in volatiles between Cl and C2 is greater than 75% for compositions C2 derived from compositions Cl of examples 1 and 3 to 7 and greater than 60% for composition C2 derived from composition Cl of example 8, whereas it is less than 50% for composition C2 derived from composition Cl of example 2 and less than 40% for composition C2 derived from composition Cl of example 9.

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, 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 volatile constituent(s) being from 0.1 to 21% 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 to separate the element comprising said composition from other elements not recyclable with said method and present in said product,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 continuously melting and transporting a polyamide, c) introducing said untreated product and optionally shaped in step b) or said separate element from step a) and optionally shaped in step b) into a system capable of continuously melting and transporting a polymer and having a degassing surface, in particular under reduced pressure, in particular said system is an extruder, in particular a multi-screw extruder, in particular a multi-rotational system extruder, d) extruding with degassing, in particular under reduced pressure, continuously in the molten state said optionally shaped product or said separate polyamide shaped and introduced in step c) 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 one or more volatile constituent(s), e) 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 volatile constituent(s) lower than the initial proportion present in said initial composition., 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-blowing, rotational molding or injection, a production start product of said structure, an end product of said structure and a production scrap of said structure.

3. Method according to claim 1 or 2, characterized in that said extrusion with degassing of step d) is carried out under reduced pressure for a time greater than or equal to 1 min.

4. Method according to one of claims 1 to 3, characterized in that said degassing surface is > 5000 mm 2 / kg / h.

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

6. Method according to one of claims 1 to 5, characterized in that the reduced pressure is between 0.1 hPa and 40 hPa.

7. Method according to one of claims 1 to 6, characterized in that said constituents are removed at least 60% by weight relative to the total weight of the constituents present in said product or said polyamide.

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

9. Method according to claim 8, characterized in that said volatile compounds are chosen from a plasticizer, a monomer and an oligomer having a degree of polymerization less than or equal to 3, and organic stabilizers.

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 relative to the total weight of the polyamide or of the composition comprising it 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) or d).

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 or 0.8 and 1.

2.

15. Method according to one of claims 11 to 14, 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).

16. Method according to one of claims 1 to 15, characterized in that the polyamide of the final composition obtained in step e) after shaping in the form of granules or a new extruded part has an NH2 / COOH ratio of from 0.75 to 1.

25.

17. Method according to one of claims 1 to 16, 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.

18. Method according to one of claims 1 to 17, characterized in that said polyamide is a semi-crystalline polyamide, in particular semi-crystalline aliphatic.

19. Product obtainable by the process according to one of claims 1 to 18.

20. Initial composition comprising one or more volatile or non-volatile constituent(s) before use, as defined in one of claims 1 to 18, said composition being called Cl and comprising by weight: (a) from 30% to 99.9% polyamide, (b) from 0.1 to 15% of plasticizer, (c) from 0 to 30% of shock modifiers, (d) from 0 to 5% of additives, (e) from 0 to 6% by weight of monomers and oligomers having a degree of polymerization less than or equal to 3, (f) from 0 to 50% by weight of fibers and / or fillers, the sum of constituents (a) to (f) being equal to 100% and the initial proportion of said volatile constituent(s) (b) and (e) being from 0.1 to 21% by weight relative to the total weight of said initial composition Cl.

21. Final composition after recycling of composition Cl defined in claim 20 and called C2, comprising by weight: (a) from 30% to 99.999% polyamide, (b) from 0 to 0.1% by weight, (c) from 0 to 30% of shock modifiers, (d) from 0 to 5% of additives, (e) from 0 to 1% by weight of monomers and oligomers having a degree of polymerization less than or equal to 3, (f) from 0 to 50% by weight of fibers and / or fillers, the sum of constituents (a) to (f) being equal to 100% and the final proportion of said volatile constituent(s) (b) and (e) being from 0 to 1.1% by weight relative to the total weight of said composition C2.

22. Use of the granules obtained in step e) of the process according to one of claims 1 to 18, for the preparation of articles obtained by extrusion.

23. Use according to claim 22 characterized in that the article is a single-layer or multi-layer structure for transporting, distributing or storing fluids.

24. Use of the granules from step e) of the process according to one of claims 1 to 18, for the preparation of articles obtained by injection.

25. Use according to claim 24, characterized in that the article relates to applications in electrical or electronics, in particular electrical and electronic equipment, or applications in sport or optical applications.

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